1
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Shi K, Wu C, Zhang H, Tong KN, He W, Li W, Jin Z, Jung S, Li S, Wang X, Gong S, Zhang Y, Zhang D, Kang F, Chi Y, Yang C, Wei G. Enhanced Emitting Dipole Orientation Based on Asymmetric Iridium(III) Complexes for Efficient Saturated-Blue Phosphorescent OLEDs. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024:e2402349. [PMID: 39137939 DOI: 10.1002/advs.202402349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Revised: 06/02/2024] [Indexed: 08/15/2024]
Abstract
Three novel asymmetric Ir(III) complexes have been rationally designed to optimize their emitting dipole orientations (EDO) and enhance light outcoupling in blue phosphorescent organic light-emitting diodes (OLEDs), thereby boosting their external quantum efficiency (EQE). Bulky electron-donating groups (EDGs), namely: carbazole (Cz), di-tert-butyl carbazole (tBuCz), and phenoxazine (Pxz) are incorporated into the tridentate dicarbene pincer chelate to induce high degree of packing anisotropy, simultaneously enhancing their photophysical properties. Angle-dependent photoluminescence (ADPL) measurements indicate increased horizontal transition dipole ratios of 0.89 and 0.90 for the Ir(III) complexes Cz-dfppy-CN and tBuCz-dfppy-CN, respectively. Analysis of the single crystal structure and density functional theory (DFT) calculation results revealed an inherent correlation between molecular aspect ratio and EDO. Utilizing the newly obtained emitters, the blue OLED devices demonstrated exceptional performance, achieving a maximum EQE of 30.7% at a Commission International de l'Eclairage (CIE) coordinate of (0.140, 0.148). Optical transfer matrix-based simulations confirmed a maximum outcoupling efficiency of 35% due to improved EDO. Finally, the tandem OLED and hyper-OLED devices exhibited a maximum EQE of 44.2% and 31.6%, respectively, together with good device stability. This rational molecular design provides straightforward guidelines to reach highly efficient and stable saturated blue emission.
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Affiliation(s)
- Kefei Shi
- Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University, Shenzhen, 518055, China
- Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Chengcheng Wu
- Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University, Shenzhen, 518055, China
- Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - He Zhang
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan, 430072, China
| | - Kai-Ning Tong
- Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Wei He
- Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Wansi Li
- Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University, Shenzhen, 518055, China
| | - Zhaoyun Jin
- Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Sinyeong Jung
- Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University, Shenzhen, 518055, China
- Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Siqi Li
- Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Xin Wang
- Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Shaolong Gong
- Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan, 430072, China
| | - Yuewei Zhang
- Laboratory of Flexible Electronics Technology, Tsinghua University, Beijing, China
| | - Dongdong Zhang
- Key Laboratory of Organic Optoelectronics and Molecular Engineering of Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, China
| | - Feiyu Kang
- Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Yun Chi
- Department of Materials Science and Engineering, Department of Chemistry and Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Hong Kong SAR, 999077, China
| | - Chuluo Yang
- Shenzhen Key Laboratory of New Information Display and Storage Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060, China
| | - Guodan Wei
- Tsinghua-Berkeley Shenzhen Institute (TBSI), Tsinghua University, Shenzhen, 518055, China
- Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
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2
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Lee Y, Cheng S, Ediger MD. High Density Two-Component Glasses of Organic Semiconductors Prepared by Physical Vapor Deposition. J Phys Chem Lett 2024:8085-8092. [PMID: 39087749 DOI: 10.1021/acs.jpclett.4c01508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2024]
Abstract
Physical vapor deposition (PVD) is widely utilized for the production of organic semiconductor devices due to its ability to form thin layers with exceptional properties. Although the layers in the device usually consist of two or more components, there is limited understanding about the fundamental characteristics of such multicomponent vapor-deposited glasses. Here, spectroscopic ellipsometry was employed to characterize the densities, thermal stabilities, and optical properties of covapor deposited NPD and TPD glasses across the entire range of composition. We find that codeposited NPD and TPD form high density glasses with enhanced thermal stability. The dependences of density and stability upon substrate temperature are correlated, and the birefringence of the codeposited glasses is determined by the reduced substrate temperature of mixtures. Additionally, we observe that the transformation of a highly stable and dense two-component glass into its supercooled liquid initiates from the free surface and propagates into the bulk at a constant velocity, like single component PVD glasses. All of these features are consistent with the surface equilibration mechanism.
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Affiliation(s)
- Yejung Lee
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Shinian Cheng
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - M D Ediger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
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3
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Madushani B, Mamada M, Goushi K, Katagiri H, Nakanotani H, Hatakeyama T, Adachi C. Hexacarbazolylbenzene: An Excellent Host Molecule Causing Strong Guest Molecular Orientation and the High-Performance OLEDs. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2402275. [PMID: 38865445 DOI: 10.1002/adma.202402275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Revised: 05/19/2024] [Indexed: 06/14/2024]
Abstract
Hexacarbazolylbenzene (6CzPh), which is benzene substituted by six carbazole rings, is a simple and attractive compound. Despite the success of a wide variety of carbazole derivatives in organic light-emitting diodes (OLEDs), 6CzPh has not received attention so far. Here, excellent performances of 6CzPh are revealed as a host material in OLEDs regarding conventional host materials. Various strategies are implemented to improve the performance of OLEDs, e.g., triplet utilization by thermally activated delayed fluorescence (TADF) and phosphorescence emitters for maximizing internal quantum efficiency, and molecular orientation control for increasing outcoupling efficiency. The present host material is suited for both criteria. Robustness of the structure and sufficiently high triplet energy enables a high external quantum efficiency with a long device lifetime. Besides, the host material boosts the horizontal molecular orientations of several guest emitters. It is noteworthy that disk-shaped 4CzIPN marks the complete horizontal molecular orientations (Θh = 100%, S = -0.50). These results provide an effective way of improving efficiencies without sacrificing device durability for future OLEDs.
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Affiliation(s)
- Bhagya Madushani
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, Fukuoka, 819-0395, Japan
| | - Masashi Mamada
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Kenichi Goushi
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, Fukuoka, 819-0395, Japan
- International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, Nishi, Fukuoka, 819-0395, Japan
| | - Hiroshi Katagiri
- Graduate School of Organic Materials Science, Yamagata University, Yonezawa, Yamagata, 992-8510, Japan
| | - Hajime Nakanotani
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, Fukuoka, 819-0395, Japan
- International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, Nishi, Fukuoka, 819-0395, Japan
| | - Takuji Hatakeyama
- Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Chihaya Adachi
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, Fukuoka, 819-0395, Japan
- International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, Nishi, Fukuoka, 819-0395, Japan
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4
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Li G, Xu K, Zheng J, Fang X, Lou W, Zhan F, Deng C, Yang YF, Zhang Q, She Y. High-Performance Ultraviolet Organic Light-Emitting Diodes Enabled by Double Boron-Oxygen-Embedded Benzo[ m]tetraphene Emitters. J Am Chem Soc 2024; 146:1667-1680. [PMID: 38175122 DOI: 10.1021/jacs.3c12517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Ultraviolet organic light-emitting diodes (UV OLEDs) have attracted increasing attention because of their promising applications in healthcare, industry, and agriculture; however, their development has been hindered by the shortage of robust UV emitters. Herein, we embedded double boron-oxygen units into nonlinear polycyclic aromatic hydrocarbons (BO-PAHs) to regulate their molecular configurations and excited-state properties, enabling novel bent BO-biphenyl (BO-bPh) and helical BO-naphthyl (BO-Nap) emitters with hybridized local and charge-transfer (HLCT) characteristics. They could be facilely synthesized in gram-scale amounts via a highly efficient two-step route. BO-bPh and BO-Nap showed strong UV and violet-blue photoluminescence in toluene with full width at half-maximum values of 25 and 37 nm, along with quantum efficiencies of 98 and 99%, respectively. A BO-bPh-based OLED showed high color purity UV electroluminescence peaking at 394 nm with Commission Internationale de l'Eclairage (CIE) coordinates of (0.166, 0.021). Moreover, the device demonstrated a record-high maximum external quantum efficiency (EQE) of 11.3%, achieved by successful hot exciton utilization. This work demonstrates the promising potential of double BO-PAHs as robust emitters for future UV OLEDs.
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Affiliation(s)
- Guijie Li
- College of Chemical Engineering, State Key Laboratory Breeding Base of Green-Chemical Synthesis Technology, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, P. R. China
| | - Kewei Xu
- College of Chemical Engineering, State Key Laboratory Breeding Base of Green-Chemical Synthesis Technology, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, P. R. China
| | - Jianbing Zheng
- College of Chemical Engineering, State Key Laboratory Breeding Base of Green-Chemical Synthesis Technology, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, P. R. China
| | - Xiaoli Fang
- College of Chemical Engineering, State Key Laboratory Breeding Base of Green-Chemical Synthesis Technology, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, P. R. China
| | - Weiwei Lou
- College of Chemical Engineering, State Key Laboratory Breeding Base of Green-Chemical Synthesis Technology, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, P. R. China
| | - Feng Zhan
- College of Chemical Engineering, State Key Laboratory Breeding Base of Green-Chemical Synthesis Technology, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, P. R. China
| | - Chao Deng
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, P. R. China
| | - Yun-Fang Yang
- College of Chemical Engineering, State Key Laboratory Breeding Base of Green-Chemical Synthesis Technology, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, P. R. China
| | - Qisheng Zhang
- MOE Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, P. R. China
| | - Yuanbin She
- College of Chemical Engineering, State Key Laboratory Breeding Base of Green-Chemical Synthesis Technology, Zhejiang University of Technology, Hangzhou, Zhejiang 310014, P. R. China
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5
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Liu X, Sun Y, Hong S, Ji X, Gao W, Yuan H, Zhang Y, Lei B, Tang L, Fan Z. Synthesis of fungicidal morpholines and isochromenopyridinones via acid-catalyzed intramolecular reactions of isoindolinones. Org Biomol Chem 2023; 22:120-125. [PMID: 38050463 DOI: 10.1039/d3ob01717f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/06/2023]
Abstract
Acid-catalyzed intramolecular cyclization or rearrangement of isoindolinone derivatives is described. 3-Hydroxy/ethoxy-3,4-dihydro-6H-[1,4]-oxazino-[3,4-a]-isoindol-6-ones are obtained in moderate to good yields. Further acid-catalyzed intramolecular rearrangement reactions give 6H-isochromeno-[4,3-b]-pyridin-6-ones. The mild reaction conditions with convenient starting materials show broad substrate scope and provide the target compounds as novel pesticide leads with good fungicidal or systemical acquired resistance activities.
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Affiliation(s)
- Xiaoyu Liu
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
| | - Yaru Sun
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
| | - Shuang Hong
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
| | - Xia Ji
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
| | - Wei Gao
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
| | - Haolin Yuan
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
| | - Yue Zhang
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
| | - Bin Lei
- Pesticide Production and Experiment Center, Xinjiang Academy of Agricultural Sciences, Urumqi 830091, China
| | - Liangfu Tang
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
- Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
| | - Zhijin Fan
- State Key Laboratory of Elemento-Organic Chemistry, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
- Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, Tianjin 300071, People's Republic of China
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6
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Ferron T, Fiori ME, Ediger MD, DeLongchamp DM, Sunday DF. Composition Dictates Molecular Orientation at the Heterointerfaces of Vapor-Deposited Glasses. JACS AU 2023; 3:1931-1938. [PMID: 37502150 PMCID: PMC10369407 DOI: 10.1021/jacsau.3c00168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Revised: 05/22/2023] [Accepted: 06/09/2023] [Indexed: 07/29/2023]
Abstract
Physical vapor deposition (PVD) can prepare organic glasses with a preferred molecular orientation. The relationships between deposition conditions and orientation have been extensively investigated in the film bulk. The role of interfaces on the structure is less well understood and remains a key knowledge gap, as the interfacial region can govern glass stability and optoelectronic properties. Robust experimental characterization has remained elusive due to complexities in interrogating molecular organization in amorphous, organic materials. Polarized soft X-rays are sensitive to both the composition and the orientation of transition dipole moments in the film, making them uniquely suited to probe molecular orientation in amorphous soft matter. Here, we utilize polarized resonant soft X-ray reflectivity (P-RSoXR) to simultaneously depth profile the composition and molecular orientation of a bilayer prepared through the physical vapor deposition of 1,4-di-[4-(N,N-diphenyl)amino]styryl-benzene (DSA-Ph) on a film of aluminum-tris(8-hydroxyquinoline) (Alq3). The bulk orientation of the DSA-Ph layer is controlled by varying deposition conditions. Utilizing P-RSoXR to depth profile the films enables determination of both the bulk orientation of DSA-Ph and the orientation near the Alq3 interface. At the Alq3 surface, DSA-Ph always lies with its long axis parallel to the interface, before transitioning into the bulk orientation. This is likely due to the lower mobility and higher glass transition of Alq3, as the first several monolayers of DSA-Ph deposited on Alq3 appear to behave as a blend. We further show how orientation at the interface correlates with the bulk behavior of a codeposited glass of similar blend composition, demonstrating a straightforward approach to predicting molecular orientation at heterointerfaces. This work provides key insights into how molecules orient during vapor deposition and offers methods to predict this property, a critical step toward controlling interfacial behavior in soft matter.
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Affiliation(s)
- Thomas
J. Ferron
- National
Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Marie E. Fiori
- Department
of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - M. D. Ediger
- Department
of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Dean M. DeLongchamp
- National
Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Daniel F. Sunday
- National
Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
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7
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Cheng S, Lee Y, Yu J, Yu L, Ediger MD. Surface Equilibration Mechanism Controls the Stability of a Model Codeposited Glass Mixture of Organic Semiconductors. J Phys Chem Lett 2023; 14:4297-4303. [PMID: 37129465 DOI: 10.1021/acs.jpclett.3c00728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
While previous work has identified the conditions for preparing ultrastable single-component organic glasses by physical vapor deposition (PVD), little is known about the stability of codeposited mixtures. Here, we prepared binary PVD glasses of organic semiconductors, TPD (N,N'-Bis(3-methylphenyl)-N,N'-diphenylbenzidine) and m-MTDATA (4,4',4″-Tris[phenyl(m-tolyl)amino]triphenylamine), with a 50:50 mass concentration over a wide range of substrate temperatures (Tsub). The enthalpy and kinetic stability are evaluated with differential scanning calorimetry and spectroscopic ellipsometry. Binary organic semiconductor glasses with exceptional thermodynamic and kinetic stability comparable to the most stable single-component organic glasses are obtained when deposited at Tsub = 0.78-0.90Tg (where Tg is the conventional glass transition temperature). When deposited at 0.94Tg, the enthalpy of the m-MTDATA/TPD glass equals that expected for the equilibrium liquid at that temperature. Thus, the surface equilibration mechanism previously advanced for single-component PVD glasses is also applicable for these codeposited glasses. These results provide an avenue for designing high-performance organic electronic devices.
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Affiliation(s)
- Shinian Cheng
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Yejung Lee
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Junguang Yu
- School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - Lian Yu
- School of Pharmacy, University of Wisconsin-Madison, Madison, Wisconsin 53705, United States
| | - M D Ediger
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
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8
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Fu Y, Liu H, Tang BZ, Zhao Z. Realizing efficient blue and deep-blue delayed fluorescence materials with record-beating electroluminescence efficiencies of 43.4. Nat Commun 2023; 14:2019. [PMID: 37037820 PMCID: PMC10086064 DOI: 10.1038/s41467-023-37687-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 03/28/2023] [Indexed: 04/12/2023] Open
Abstract
As promising luminescent materials for organic light-emitting diodes (OLEDs), thermally activated delayed fluorescence materials are booming vigorously in recent years, but robust blue ones still remain challenging. Herein, we report three highly efficient blue and deep-blue delayed fluorescence materials comprised of a weak electron acceptor chromeno[3,2-c]carbazol-8(5H)-one with a rigid polycyclic structure and a weak electron donor spiro[acridine-9,9'-xanthene]. They hold distinguished merits of excellent photoluminescence quantum yields (99%), ultrahigh horizontal transition dipole ratios (93.6%), and fast radiative transition and reverse intersystem crossing, which furnish superb blue and deep-blue electroluminescence with Commission Internationale de I'Eclairage coordinates (CIEx,y) of (0.14, 0.18) and (0.14, 0.15) and record-beating external quantum efficiencies (ηexts) of 43.4% and 41.3%, respectively. Their efficiency roll-offs are successfully reduced by suppressing triplet-triplet and singlet-singlet annihilations. Moreover, high-performance deep-blue and green hyperfluorescence OLEDs are achieved by utilizing these materials as sensitizers for multi-resonance delayed fluorescence dopants, providing state-of-the-art ηexts of 32.5% (CIEx,y = 0.14, 0.10) and 37.6% (CIEx,y = 0.32, 0.64), respectively, as well as greatly advanced operational lifetimes. These splendid results can surely inspire the development of blue and deep-blue luminescent materials and devices.
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Affiliation(s)
- Yan Fu
- State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, South China University of Technology, Guangzhou, 510640, China
| | - Hao Liu
- State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, South China University of Technology, Guangzhou, 510640, China
| | - Ben Zhong Tang
- School of Science and Engineering, Shenzhen Institute of Aggregate Science and Technology, The Chinese University of Hong Kong, Shenzhen, Guangdong, 518172, China
| | - Zujin Zhao
- State Key Laboratory of Luminescent Materials and Devices, Guangdong Provincial Key Laboratory of Luminescence from Molecular Aggregates, South China University of Technology, Guangzhou, 510640, China.
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9
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Fiedler J, Berland K, Borchert JW, Corkery RW, Eisfeld A, Gelbwaser-Klimovsky D, Greve MM, Holst B, Jacobs K, Krüger M, Parsons DF, Persson C, Presselt M, Reisinger T, Scheel S, Stienkemeier F, Tømterud M, Walter M, Weitz RT, Zalieckas J. Perspectives on weak interactions in complex materials at different length scales. Phys Chem Chem Phys 2023; 25:2671-2705. [PMID: 36637007 DOI: 10.1039/d2cp03349f] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Nanocomposite materials consist of nanometer-sized quantum objects such as atoms, molecules, voids or nanoparticles embedded in a host material. These quantum objects can be exploited as a super-structure, which can be designed to create material properties targeted for specific applications. For electromagnetism, such targeted properties include field enhancements around the bandgap of a semiconductor used for solar cells, directional decay in topological insulators, high kinetic inductance in superconducting circuits, and many more. Despite very different application areas, all of these properties are united by the common aim of exploiting collective interaction effects between quantum objects. The literature on the topic spreads over very many different disciplines and scientific communities. In this review, we present a cross-disciplinary overview of different approaches for the creation, analysis and theoretical description of nanocomposites with applications related to electromagnetic properties.
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Affiliation(s)
- J Fiedler
- Department of Physics and Technology, University of Bergen, Allégaten 55, 5007 Bergen, Norway.
| | - K Berland
- Department of Mechanical Engineering and Technology Management, Norwegian University of Life Sciences, Campus Ås Universitetstunet 3, 1430 Ås, Norway
| | - J W Borchert
- 1st Institute of Physics, Georg-August-University, Göttingen, Germany
| | - R W Corkery
- Surface and Corrosion Science, Department of Chemistry, KTH Royal Institute of Technology, SE 100 44 Stockholm, Sweden
| | - A Eisfeld
- Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Strasse 38, 01187 Dresden, Germany
| | - D Gelbwaser-Klimovsky
- Schulich Faculty of Chemistry and Helen Diller Quantum Center, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - M M Greve
- Department of Physics and Technology, University of Bergen, Allégaten 55, 5007 Bergen, Norway.
| | - B Holst
- Department of Physics and Technology, University of Bergen, Allégaten 55, 5007 Bergen, Norway.
| | - K Jacobs
- Experimental Physics, Saarland University, Center for Biophysics, 66123 Saarbrücken, Germany.,Max Planck School Matter to Life, 69120 Heidelberg, Germany
| | - M Krüger
- Institute for Theoretical Physics, Georg-August-Universität Göttingen, 37073 Göttingen, Germany
| | - D F Parsons
- Department of Chemical and Geological Sciences, University of Cagliari, Cittadella Universitaria, 09042 Monserrato, CA, Italy
| | - C Persson
- Centre for Materials Science and Nanotechnology, University of Oslo, P. O. Box 1048 Blindern, 0316 Oslo, Norway.,Department of Materials Science and Engineering, KTH Royal Institute of Technology, 100 44 Stockholm, Sweden
| | - M Presselt
- Leibniz Institute of Photonic Technology (IPHT), Albert-Einstein-Str. 9, 07745 Jena, Germany
| | - T Reisinger
- Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
| | - S Scheel
- Institute of Physics, University of Rostock, Albert-Einstein-Str. 23-24, 18059 Rostock, Germany
| | - F Stienkemeier
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - M Tømterud
- Department of Physics and Technology, University of Bergen, Allégaten 55, 5007 Bergen, Norway.
| | - M Walter
- Institute of Physics, University of Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
| | - R T Weitz
- 1st Institute of Physics, Georg-August-University, Göttingen, Germany
| | - J Zalieckas
- Department of Physics and Technology, University of Bergen, Allégaten 55, 5007 Bergen, Norway.
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10
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Ishtaiwi Z, Taher D, Korb M, Helal W, Al-Hunaiti A, Juwhari HK, Amarne H, Amer MW, YouSef YA, Klaib S, Abu-Orabi ST. Syntheses, crystal structures, DFT calculation and solid-state spectroscopic properties of new zincate(II) complexes with N-(4-substituted phenyl)-N'-(4-nitrophenyl)-oxamate. ARAB J CHEM 2022. [DOI: 10.1016/j.arabjc.2022.104349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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11
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A theoretical analysis on the electron and energy transfer between host and guest materials in phosphor–doped OLED. J Photochem Photobiol A Chem 2022. [DOI: 10.1016/j.jphotochem.2022.114058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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12
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Xiong WJ, Zhang XB, Dou SB, Quan ZM, Li DW, Niu ZG, Li GN. Green to red-emitting neutral iridium complexes with phenyl-indazole type cyclometalating ligand: Synthesis, photophysical properties and DFT calculations. Inorganica Chim Acta 2022. [DOI: 10.1016/j.ica.2022.121100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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13
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Kim J, Hwang KY, Kim S, Lim J, Kang B, Lee KH, Choi B, Kwak S, Lee JY. Enhancing Horizontal Ratio of Transition Dipole Moment in Homoleptic Ir Complexes for High Outcoupling Efficiency of Organic Light-Emitting Diodes. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2203903. [PMID: 36055795 PMCID: PMC9631091 DOI: 10.1002/advs.202203903] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 08/12/2022] [Indexed: 06/15/2023]
Abstract
The light-emitting dipole orientation (EDO) of a phosphorescent emitter is a key to improving the external quantum efficiency (EQE) of organic light-emitting diodes (OLEDs) without structural modification of the device. Here, four homoleptic Ir complexes as a phosphorescent emitter are systematically designed based on the molecular structure of tris(2-phenylpyridine)iridium(III) (Ir(ppy)3 ) to control the EDO. Trimethylsilane, methyl, 2-methylpropyl, and cyclopentylmethyl group substituted to pyridine ring of the ligand contribute to the improvement of the EDO from 76.5% for Ir(ppy)3 to 87.5%. A linear relationship between the EDO and the aspect ratio (geometric anisotropy factor) is founded, implying the importance of the effective area for the nonbonding force between host and dopant molecules. Also, it is investigated that the EDO enhancement mainly originates from the vertical alignment of the C3 axis of molecule in the substrate axis rather than the change in the direction of the transition dipole alignment in the molecular axis. The optical simulation reveals that the outcoupling efficiency of phosphorescent OLEDs adopting new dopants reaches 38.4%. The green OLEDs exhibiting 28.3% of EQE, 103.2 cd A-1 of current efficiency, and 98.2 lm W-1 of power efficiency are demonstrated, which is understood to have little electrical loss.
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Affiliation(s)
- Jae‐Min Kim
- School of Chemical EngineeringSungkyunkwan University2066, Seobu‐ro, Jangan‐guSuwonGyeonggi‐do16419Republic of Korea
| | - Kyu Young Hwang
- Samsung Advanced Institute of TechnologySamsung Electronics Co. Ltd.SuwonGyeonggi‐do16678Republic of Korea
| | - Sungmin Kim
- Samsung Advanced Institute of TechnologySamsung Electronics Co. Ltd.SuwonGyeonggi‐do16678Republic of Korea
| | - Junseop Lim
- School of Chemical EngineeringSungkyunkwan University2066, Seobu‐ro, Jangan‐guSuwonGyeonggi‐do16419Republic of Korea
| | - Byungjoon Kang
- Samsung Advanced Institute of TechnologySamsung Electronics Co. Ltd.SuwonGyeonggi‐do16678Republic of Korea
| | - Kum Hee Lee
- Samsung Advanced Institute of TechnologySamsung Electronics Co. Ltd.SuwonGyeonggi‐do16678Republic of Korea
| | - Byoungki Choi
- Samsung Advanced Institute of TechnologySamsung Electronics Co. Ltd.SuwonGyeonggi‐do16678Republic of Korea
| | - Seung‐Yeon Kwak
- Samsung Advanced Institute of TechnologySamsung Electronics Co. Ltd.SuwonGyeonggi‐do16678Republic of Korea
| | - Jun Yeob Lee
- School of Chemical EngineeringSungkyunkwan University2066, Seobu‐ro, Jangan‐guSuwonGyeonggi‐do16419Republic of Korea
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14
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Shen P, Liu H, Zhuang Z, Zeng J, Zhao Z, Tang BZ. Through-Space Conjugated Electron Transport Materials for Improving Efficiency and Lifetime of Organic Light-Emitting Diodes. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2200374. [PMID: 35322599 PMCID: PMC9130898 DOI: 10.1002/advs.202200374] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/03/2022] [Indexed: 05/05/2023]
Abstract
Thermally stable electron transport (ET) materials with high electron mobility and high triplet state energy level are highly desired for the fabrication of efficient and stable organic light-emitting diodes (OLEDs). Herein, a new design strategy of constructing through-space conjugated folded configuration is proposed to explore robust ET materials, opposite to the widely used planar configuration. By bonding two quinolines to the 9,10-positions of phenanthrene, two novel folded molecules with high thermal and morphological stabilities and high triplet state energy levels (>2.7 eV) are created. These folded molecules possess excellent ET ability with electron mobilities of three orders of magnitude higher than those of linear and planar counterparts. Theoretical calculation and crystallography analysis demonstrate the through-space conjugated folded configuration has not only reduced reorganization energy but also enlarged charge transfer integral at various dimensions, bringing about efficient multi-dimensional ET, independent of molecular orientation. By adopting the folded molecule as ET layers, OLEDs with no matter delayed fluorescence or phosphorescence emitters can achieve high external quantum efficiencies and long operational lifetimes simultaneously. This work paves a new avenue towards robust ET materials to improve efficiency and stability of OLEDs.
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Affiliation(s)
- Pingchuan Shen
- State Key Laboratory of Luminescent Materials and DevicesGuangdong Provincial Key Laboratory of Luminescence from Molecular AggregatesSouth China University of TechnologyGuangzhou510640China
| | - Hao Liu
- State Key Laboratory of Luminescent Materials and DevicesGuangdong Provincial Key Laboratory of Luminescence from Molecular AggregatesSouth China University of TechnologyGuangzhou510640China
| | - Zeyan Zhuang
- State Key Laboratory of Luminescent Materials and DevicesGuangdong Provincial Key Laboratory of Luminescence from Molecular AggregatesSouth China University of TechnologyGuangzhou510640China
| | - Jiajie Zeng
- State Key Laboratory of Luminescent Materials and DevicesGuangdong Provincial Key Laboratory of Luminescence from Molecular AggregatesSouth China University of TechnologyGuangzhou510640China
| | - Zujin Zhao
- State Key Laboratory of Luminescent Materials and DevicesGuangdong Provincial Key Laboratory of Luminescence from Molecular AggregatesSouth China University of TechnologyGuangzhou510640China
| | - Ben Zhong Tang
- State Key Laboratory of Luminescent Materials and DevicesGuangdong Provincial Key Laboratory of Luminescence from Molecular AggregatesSouth China University of TechnologyGuangzhou510640China
- Shenzhen Institute of Aggregate Science and TechnologySchool of Science and EngineeringThe Chinese University of Hong KongShenzhenGuangdong518172China
- AIE InstituteGuangzhou Development DistrictHuangpuGuangzhou510530China
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15
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Van der Zee B, Li Y, Wetzelaer GJAH, Blom PWM. Efficiency of Polymer Light-Emitting Diodes: A Perspective. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2108887. [PMID: 34786784 DOI: 10.1002/adma.202108887] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Indexed: 06/13/2023]
Abstract
The various contributions to the external quantum efficiency (EQE) of polymer light-emitting diodes (PLEDs) are discussed. The EQE of an organic light-emitting diode is governed by a number of parameters, such as the electrical efficiency, the photoluminescence quantum yield (PLQY), the optical outcoupling efficiency and the spin statistics for singlet exciton generation. In the last decade, the electrical efficiency has been determined from a numerical PLED device model. More recently, an optical model to simulate the fraction of photons outcoupled to air for PLEDs with a broad recombination zone has been developed. Together with the directly measured PLQY, the EQE of a PLED can then be estimated. However, it has been observed that the measured EQEs of fluorescent PLEDs, including the model system super-yellow poly(p-phenylene vinylene) (SY-PPV) often exceed the expected values. To solve this discrepancy, it is demonstrate that the electrical PLED model has to be expanded by the inclusion of triplet-triplet annihilation (TTA), which is shown to be responsible for a substantial EQE enhancement. Experimentally, it is obtained that TTA contributes to a singlet-exciton generation efficiency of ≈40% in SY-PPV PLEDs, giving rise to an EQE of ≈4% instead of the expected value of 2.5%.
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Affiliation(s)
- Bas Van der Zee
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz, 55128, Germany
| | - Yungui Li
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz, 55128, Germany
| | | | - Paul W M Blom
- Max Planck Institute for Polymer Research, Ackermannweg 10, Mainz, 55128, Germany
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16
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Wang D, Ma Z, Xi J, Wang N, Wang T, Liang Y, zhang Z. Synthesis of V‐shaped bis‐coumarins via Aldol reaction/double Lactonization cascade reaction from bis(2‐hydroxyphenyl)methanone and Meldrum's acid. European J Org Chem 2022. [DOI: 10.1002/ejoc.202101489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Ding Wang
- Shaanxi Normal University School of Chemistry and Chemical Engineering CHINA
| | - Zhishuang Ma
- Shaanxi Normal University Basic Experimental Teaching Center CHINA
| | - Jin Xi
- Shaanxi Normal University School of Chemistry and Chemical Engineering CHINA
| | - Nana Wang
- Shaanxi Normal University School of Chemistry and Chemical Engineering CHINA
| | - Tao Wang
- Shaanxi Normal University School of Chemistry and Chemical Engineering CHINA
| | - Yong Liang
- Beckman Research Institute Department of molecular medicine CHINA
| | - zunting zhang
- Shaanxi Normal University School of Chemistry and Chemical Engineering West Chang'an Avenue, Chang'an District 710119 xi'an CHINA
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17
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Chen S, Bi H, Tian W, Liu Y. Deep-Red and Near-Infrared Iridium Complexes with Fine-Tuned Emission Colors by Adjusting Trifluoromethyl Substitution on Cyclometalated Ligands Combined with Matched Ancillary Ligands for Highly Efficient Phosphorescent Organic Light-Emitting Diodes. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27010286. [PMID: 35011518 PMCID: PMC8746706 DOI: 10.3390/molecules27010286] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 12/27/2021] [Accepted: 12/31/2021] [Indexed: 11/16/2022]
Abstract
Six novel Ir(C^N)2(L^X)-type heteroleptic iridium complexes with deep-red and near-infrared region (NIR)-emitting coverage were constructed through the cross matching of various cyclometalating (C^N) and ancillary (LX) ligands. Here, three novel C^N ligands were designed by introducing the electron-withdrawing group CF3 on the ortho (o-), meta (m-), and para (p-) positions of the phenyl ring in the 1-phenylisoquinoline (piq) group, which were combined with two electron-rich LX ligands (dipba and dipg), respectively, leading to subsequent iridium complexes with gradually changing emission colors from deep red (≈660 nm) to NIR (≈700 nm). Moreover, a series of phosphorescent organic light-emitting diodes (PhOLEDs) were fabricated by employing these phosphors as dopant emitters with two doping concentrations, 5% and 10%, respectively. They exhibited efficient electroluminescence (EL) with significantly high EQE values: >15.0% for deep red light0 (λmax = 664 nm) and >4.0% for NIR cases (λmax = 704 nm) at a high luminance level of 100 cd m-2. This work not only provides a promising approach for finely tuning the emission color of red phosphors via the easily accessible molecular design strategy, but also enables the establishment of an effective method for enriching phosphorescent-emitting molecules for practical applications, especially in the deep-red and near-infrared region (NIR).
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Affiliation(s)
- Shuonan Chen
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China;
| | - Hai Bi
- Jihua Laboratory, 13 Nanpingxi Road, Foshan 528200, China
- Correspondence: (H.B.); (W.T.); (Y.L.)
| | - Wenjing Tian
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China;
- Correspondence: (H.B.); (W.T.); (Y.L.)
| | - Yu Liu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, China;
- Correspondence: (H.B.); (W.T.); (Y.L.)
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18
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Li Q, Shi C, Huang M, Wu C, Wang H, Wu H, Zheng Y, Yang C, Yuan A. Three Types of Charged Ligands Based Carboxyl-Containing Iridium(III) Complexes: Structures, Photophysics, and Solution Processed OLED Application. Inorg Chem 2021; 60:17699-17704. [PMID: 34739254 DOI: 10.1021/acs.inorgchem.1c02296] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A novel family of three types of charged (0, -1, -2) ligands based phosphorescent iridium(III) complexes with different carboxyl-containing dianionic (-2) ligands have been synthesized. Their single-crystal structures show that all neutral complexes (Ir1, Ir2, and Ir3) show a trans-N^N configuration between dianionic (-2) and monoanionic (-1) ligands, which is in contrast with the trans-N^C configuration in cationic complex Ir4, which has an interesting hydrogen bond in the solid state. Notably, Ir4 shows higher luminescence efficiency and an obvious blue shift emission relative to those in Ir1, Ir2, and Ir3. DFT calculations demonstrate that all neutral complexes (Ir1, Ir2, and Ir3) exhibit ligand-to-ligand charge transfer (LLCT) excited state character from the dianionic (-2) ligand to the neutral (0) ligand, which are completely different from the cationic complex Ir4 that exhibits an LLCT excited state from the monoanionic (-1) ligand to the neutral (0) ligand. Considering better solubility, Ir1 was eventually used in solution-processed OLED and achieved moderate efficiency (6.6%, 14.3 cd A-1, 2.8 lm W-1) with an orange light displaying CIEx,y coordinates of (0.53, 0.46). This work provides a new strategy to construct three types of charged (0, -1, -2) ligands based phosphorescent iridium(III) complexes and extends the range of iridium complex luminescent materials.
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Affiliation(s)
- Qiuxia Li
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, People's Republic of China
| | - Chao Shi
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, People's Republic of China
| | - Manli Huang
- College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, People's Republic of China
| | - Cuicui Wu
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, People's Republic of China
| | - Hongzhen Wang
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, People's Republic of China
| | - Haotian Wu
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, People's Republic of China
| | - Ying Zheng
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, People's Republic of China
| | - Chuluo Yang
- College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, People's Republic of China
| | - Aihua Yuan
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, People's Republic of China
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19
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Li Q, Shi C, Huang M, Zhang X, Sun F, Zheng Y, Yan H, Yang C, Yuan A. Three types of charged ligand-based neutral phosphorescent iridium(III) complexes featuring nido-carborane: synthesis, structures, and solution processed organic light-emitting diode applications. Dalton Trans 2021; 50:16304-16310. [PMID: 34730578 DOI: 10.1039/d1dt02990h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
In view of the fact that coordination configurations and special functional groups are both important for the optical properties of phosphorescent iridium complex materials, we have prepared a novel family of three types of charged ligand (0, -1, and -2) based neutral phosphorescent iridium(III) complexes (Ir1-Ir4) featuring nido-carborane. Single crystal structures indicate that complexes (Ir2, Ir3 and Ir4) with nido-carborane as a functional group at different substitution sites all show a trans-C^C configuration between dianionic (-2) and monoanionic (-1) ligands, which are different from the trans-N^C configuration in complex Ir1 with nido-carborane as a coordination skeleton, which has an interesting Ir-B coordination bond. Notably, Ir2, Ir3 and Ir4 all show obvious yellow light emission, while Ir1 does not emit light either in solution or in the solid state. DFT calculations demonstrate that complexes Ir2, Ir3 and Ir4 exhibit an unusual ligand-to-metal charge transfer (LMCT) excited state character due to the strong electron-donating character of nido-carborane. Considering its better solubility and luminescence properties, Ir3 was successfully applied in solution-processed organic light-emitting diodes and an effective yellow emission was achieved. This work provides a new strategy for the investigation of three types of charged ligand (0, -1, and -2) based phosphorescent iridium complex materials by constructing new dianionic ligands with nido-carborane.
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Affiliation(s)
- Qiuxia Li
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, P. R. China.
| | - Chao Shi
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, P. R. China.
| | - Manli Huang
- College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, P. R. China.
| | - Xinghua Zhang
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, P. R. China.
| | - Fangxiang Sun
- State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, P. R. China.
| | - Ying Zheng
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, P. R. China.
| | - Hong Yan
- State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, P. R. China.
| | - Chuluo Yang
- College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, P. R. China.
| | - Aihua Yuan
- School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, P. R. China.
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20
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Surface equilibration mechanism controls the molecular packing of glassy molecular semiconductors at organic interfaces. Proc Natl Acad Sci U S A 2021; 118:2111988118. [PMID: 34645709 DOI: 10.1073/pnas.2111988118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/07/2021] [Indexed: 12/31/2022] Open
Abstract
Glasses prepared by physical vapor deposition (PVD) are anisotropic, and the average molecular orientation can be varied significantly by controlling the deposition conditions. While previous work has characterized the average structure of thick PVD glasses, most experiments are not sensitive to the structure near an underlying substrate or interface. Given the profound influence of the substrate on the growth of crystalline or liquid crystalline materials, an underlying substrate might be expected to substantially alter the structure of a PVD glass, and this near-interface structure is important for the function of organic electronic devices prepared by PVD, such as organic light-emitting diodes. To study molecular packing near buried organic-organic interfaces, we prepare superlattice structures (stacks of 5- or 10-nm layers) of organic semiconductors, Alq3 (Tris-(8-hydroxyquinoline)aluminum) and DSA-Ph (1,4-di-[4-(N,N-diphenyl)amino]styrylbenzene), using PVD. Superlattice structures significantly increase the fraction of the films near buried interfaces, thereby allowing for quantitative characterization of interfacial packing. Remarkably, both X-ray scattering and spectroscopic ellipsometry indicate that the substrate exerts a negligible influence on PVD glass structure. Thus, the surface equilibration mechanism previously advanced for thick films can successfully describe PVD glass structure even within the first monolayer of deposition on an organic substrate.
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21
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Takimoto K, Watanabe Y, Yoshida J, Sato H. Five-coordinate iridium(III) complex with ΔΛ chirality. Dalton Trans 2021; 50:13256-13263. [PMID: 34608912 DOI: 10.1039/d1dt01960k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The coordinatively unsaturated bis-chelated iridium(III) complex, [Ir(2-Bubzq)2Cl] (2-BubzqH = 2-butyl-benzo[h]quinoline), denoted as complex 1, was obtained by reacting iridium(III) trichloride with 2-BubzqH in a 1 : 2 molar ratio. The results were in contrast to the common view that a chlorine-bridged dimer, [Ir(L)2Cl]2 (L = bis-chelate ligand), is formed under the corresponding conditions. A single-crystal X-ray diffraction structural analysis revealed that complex 1 has a five-coordinate geometry with a distorted square pyramidal configuration. The optical resolution of complex 1 was measured chromatographically on a chiral column, yielding Δ and Λ as enantiomers. The resolved enantiomers were stable enough against racemization in CDCl3 as confirmed by the vibrational circular dichroism measurements. Complex 1 reacted with carbon monoxide (CO) to give [Ir(2-Bubzq)2(CO)Cl] and with 1,10-phenanthroline (phen) to give [Ir(2-Bubzq)2(phen)]Cl within a minute with its absolute configuration (ΔΛ chirality) maintained.
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Affiliation(s)
- Kazuyoshi Takimoto
- Graduate School of Science and Engineering, Ehime University, 2-5 Bunkyo-chou, Matsuyama, Ehime 790-8577, Japan.
| | - Yutaka Watanabe
- Graduate School of Science and Engineering, Ehime University, 2-5 Bunkyo-chou, Matsuyama, Ehime 790-8577, Japan.
| | - Jun Yoshida
- Department of Chemistry, College of Humanities & Sciences, Nihon University, 3-25-40 Sakurajosui, Setagaya-ku, Tokyo 156-8550, Japan
| | - Hisako Sato
- Graduate School of Science and Engineering, Ehime University, 2-5 Bunkyo-chou, Matsuyama, Ehime 790-8577, Japan.
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22
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Jung MC, Facendola J, Kim J, Muthiah Ravinson DS, Djurovich PI, Forrest SR, Thompson ME. Molecular Alignment of Homoleptic Iridium Phosphors in Organic Light-Emitting Diodes. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2102882. [PMID: 34302388 DOI: 10.1002/adma.202102882] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/26/2021] [Indexed: 06/13/2023]
Abstract
The orientation of facial (fac) tris-cyclometalated iridium complexes in doped films prepared by vacuum deposition is investigated by altering the physical shape and electronic asymmetry in the molecular structure. Angle-dependent photoluminescence spectroscopy and Fourier-plane imaging microscopy show that the orientation of roughly spherical fac-tris(2-phenylpyridyl)iridium (Ir(ppy)3 ) is isotropic, whereas complexes that are oblate spheroids, fac-tris(mesityl-2-phenyl-1H-imidazole)iridium (Ir(mi)3 ) and fac-tris((3,5-dimethyl-[1,1'-biphenyl]-4-yl)-2-phenyl-1H-imidazole)iridium (Ir(mip)3 ), have a net horizontal alignment of their transition dipole moments. Optical anisotropy factors of 0.26 and 0.15, respectively, are obtained from the latter complexes when doped into tris(4-(9H-carbazol-9-yl)phenyl)amine host thin films. The horizontal alignment is attributed to the favorable van der Waals interaction between the oblate Ir complexes and host material. Trifluoromethyl groups substituted on one polar face of the Ir(ppy)3 and Ir(mi)3 complexes introduce chemical asymmetries in the molecules at the expense of their oblate shapes. The anisotropy factors of films doped with these substituted derivatives are lower relative to the parent complexes, indicating that the fluorinated patches reinforce horizontal alignment during deposition. High efficiencies obtained from organic light emitting diodes prepared using the Ir dopants is attributed, in part, to improved outcoupling of electroluminescence brought about by molecular alignment.
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Affiliation(s)
- Moon Chul Jung
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, 90089, USA
| | - John Facendola
- Department of Chemistry, University of Southern California, Los Angeles, CA, 90089, USA
| | - Jongchan Kim
- Department of Electrical and Computer Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
| | | | - Peter I Djurovich
- Department of Chemistry, University of Southern California, Los Angeles, CA, 90089, USA
| | - Stephen R Forrest
- Department of Electrical and Computer Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Physics and Materials Science and Engineering, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Mark E Thompson
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, 90089, USA
- Department of Chemistry, University of Southern California, Los Angeles, CA, 90089, USA
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23
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Tenopala-Carmona F, Lee OS, Crovini E, Neferu AM, Murawski C, Olivier Y, Zysman-Colman E, Gather MC. Identification of the Key Parameters for Horizontal Transition Dipole Orientation in Fluorescent and TADF Organic Light-Emitting Diodes. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2100677. [PMID: 34338351 DOI: 10.1002/adma.202100677] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 04/21/2021] [Indexed: 06/13/2023]
Abstract
In organic light-emitting diodes (OLEDs), horizontal orientation of the emissive transition dipole moment (TDM) can improve light outcoupling efficiency by up to 50% relative to random orientation. Therefore, there have been extensive efforts to identify drivers of horizontal orientation. The aspect ratio of the emitter molecule and the glass-transition temperature (Tg ) of the films are currently regarded as particularly important. However, there remains a paucity of systematic studies that establish the extent to which these and other parameters control orientation in the wide range of emitter systems relevant for state-of-the-art OLEDs. Here, recent work on molecular orientation of fluorescent and thermally activated delayed fluorescent emitters in vacuum-processed OLEDs is reviewed. Additionally, to identify parameters linked to TDM orientation, a meta-analysis of 203 published emitter systems is conducted and combined with density-functional theory calculations. Molecular weight (MW) and linearity are identified as key parameters in neat systems. In host-guest systems with low-MW emitters, orientation is mostly influenced by the host Tg , whereas the length and MW of the emitter become more relevant for systems involving higher-MW emitters. To close, a perspective of where the field must advance to establish a comprehensive model of molecular orientation is given.
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Affiliation(s)
- Francisco Tenopala-Carmona
- Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
- Humboldt Centre for Nano- and Biophotonics, Department of Chemistry, University of Cologne, Greinstr. 4-6, 50939, Köln, Germany
| | - Oliver S Lee
- Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK
| | - Ettore Crovini
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK
| | - Ana M Neferu
- Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK
| | - Caroline Murawski
- Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
| | - Yoann Olivier
- Unité de Chimie Physique Théorique et Structurale & Laboratoire de Physique du Solide, Namur Institute of Structured Matter, Université de Namur, Rue de Bruxelles, 61, Namur, 5000, Belgium
| | - Eli Zysman-Colman
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK
| | - Malte C Gather
- Organic Semiconductor Centre, SUPA School of Physics and Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
- Humboldt Centre for Nano- and Biophotonics, Department of Chemistry, University of Cologne, Greinstr. 4-6, 50939, Köln, Germany
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24
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Cao L, Zhu ZQ, Klimes K, Li J. Efficient and Stable Molecular-Aggregate-Based Organic Light-Emitting Diodes with Judicious Ligand Design. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2101423. [PMID: 34245184 DOI: 10.1002/adma.202101423] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 04/14/2021] [Indexed: 06/13/2023]
Abstract
Phosphorescent molecular aggregates show promise in realizing efficient and stable organic light-emitting diodes (OLEDs) operating at high brightness level, which is highly desired for future lighting and display applications. Herein, four tetradentate Pd(II) complexes are prepared with judicious ligand design, and their electrochemical and photophysical properties are thoroughly examined. The studies indicate that slight structural changes of ligands can modify the hole and electron transporting capabilities, and alter the horizontal emitting dipole ratios of aggregates in amorphous film, the latter of which are sensitive to the thin-film deposition conditions including the deposition rate and the choice of the templating layer. An optimized OLED device using Pd3O8-Py5 aggregates exhibits a peak external quantum efficiency (EQE) of 37.3% and a reduced efficiency roll-off with high EQEs of 36.0% and 32.5% at 1000 and 10 000 cd m-2 , respectively. Moreover, such an efficient device demonstrates a long measured LT95 (time to 95% of the initial luminance) lifetime of over 500 h with an initial brightness of 17 304 cd m-2 corresponding to an estimated LT95 lifetime of 48 246 h at 1000 cd m-2 .
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Affiliation(s)
- Linyu Cao
- Department of Materials Science and Engineering, Arizona State University, Tempe, AZ, 85287, USA
| | - Zhi-Qiang Zhu
- Department of Materials Science and Engineering, Arizona State University, Tempe, AZ, 85287, USA
| | - Kody Klimes
- Department of Materials Science and Engineering, Arizona State University, Tempe, AZ, 85287, USA
| | - Jian Li
- Department of Materials Science and Engineering, Arizona State University, Tempe, AZ, 85287, USA
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25
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Sohn S, Kim S, Shim JW, Jung SK, Jung S. Printed Organic Light-Emitting Diodes on Fabric with Roll-to-Roll Sputtered ITO Anode and Poly(vinyl alcohol) Planarization Layer. ACS APPLIED MATERIALS & INTERFACES 2021; 13:28521-28528. [PMID: 34105342 DOI: 10.1021/acsami.1c02681] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Electronic textiles, which are a combination of fabrics and electronics, can help realize wearable electronic devices by changing the rigidity of these textiles. We demonstrate organic light-emitting diodes (OLEDs) by directly printing the emitting material on fabric substrates using the nozzle-printing technique. Printing the emitting material directly on a fabric substrate with a rough surface is difficult. To address this, we introduce a planarization layer by using a synthesized 3.5 wt % poly(vinyl alcohol) (PVA) solution. The sputtered ITO anode with the thermally annealed PVA planarization layer on a fabric substrate achieves a low sheet resistance in the range of 60-80 Ω/sq, whereas the ITO electrode without a PVA layer exhibits high sheet resistance values of 10-25 kΩ/sq. This result is because the thermally annealed PVA layer on the fabric surface has a uniform surface morphology and a water contact angle as high as 96°, thus acting as a protective layer with a waterproofing effect; in contrast, the water is completely absorbed on the rough surface without a PVA layer. The fabric-based OLEDs with a thermally annealed PVA layer exhibit a lower turn-on voltage of 3 V and higher luminance values of 5346 cd/m2 at 8 V compared with the devices without a PVA layer (7 V and 3622 cd/m2) at 18 V. These fabric-based OLEDs with a PVA planarization layer can be produced by the nozzle-printing process and can achieve selective patterning as well as direct printing of the emitting material and ITO sputtering on a fabric substrate; furthermore, they emit well even when it bent into a circle with a radius of 1 cm.
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Affiliation(s)
- Sunyoung Sohn
- Department of Semiconductor Physics and Electronics, Sangji University, Wonju 26339, Republic of Korea
| | - Seongju Kim
- Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Jae Won Shim
- School of Electrical Engineering, Korea University, Seoul 02841, Republic of Korea
| | | | - Sungjune Jung
- Department of Mechanical Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
- Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
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26
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Cui D, Wang S, Li S, Liu Y, Gao X, Wang W, Dong X. Improving the performance of OLEDs by controlling the molecular orientation in charge carrier transport layers. OPTICS EXPRESS 2021; 29:16845-16856. [PMID: 34154237 DOI: 10.1364/oe.418566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 05/04/2021] [Indexed: 06/13/2023]
Abstract
The transition dipole moment (TDM) orientation in the emission layer (EML) of organic light-emitting diodes (OLEDs) have attracted increasing attention from many researchers. But the study point at the molecular orientation in the hole transport layer (HTL) and electron transport layer (ETL) was not reported widely. In this paper, the molecular orientation of HTLs and ETLs were controlled by the deposition rate. The angle-dependent PL spectra and the variable angle spectroscopic ellipsometry (VASE) were used for evaluating the molecular orientation of B3PYMPM and TAPC, respectively. We found that fast deposition rate can boost preferentially vertical molecular orientation in both molecules and facilitate the hole and electron mobility, which was tested by the current density-voltage and capacitance-voltage curves of HODs and EODs. Moreover, the HTLs and ETLs were employed in OLED devices to verify the influence of molecular orientation on charge carrier mobility, which determined the performance of OLEDs significantly.
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27
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Cao Y, Song J, Li G, Zheng Y, Shi C, Li Q, Yuan A. Oxygen‐Bridged Triphenylamine Units Tuning the Photophysical Properties of Classical Phosphorescent Iridium(III) Complex. ChemistrySelect 2021. [DOI: 10.1002/slct.202004750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Yibo Cao
- School of Environmental and Chemical Engineering Jiangsu University of Science and Technology Zhenjiang 212003 P. R. China
| | - Jialiang Song
- School of Environmental and Chemical Engineering Jiangsu University of Science and Technology Zhenjiang 212003 P. R. China
| | - Gang Li
- School of Environmental and Chemical Engineering Jiangsu University of Science and Technology Zhenjiang 212003 P. R. China
| | - Ying Zheng
- School of Environmental and Chemical Engineering Jiangsu University of Science and Technology Zhenjiang 212003 P. R. China
| | - Chao Shi
- School of Environmental and Chemical Engineering Jiangsu University of Science and Technology Zhenjiang 212003 P. R. China
| | - Qiuxia Li
- School of Environmental and Chemical Engineering Jiangsu University of Science and Technology Zhenjiang 212003 P. R. China
| | - Aihua Yuan
- School of Environmental and Chemical Engineering Jiangsu University of Science and Technology Zhenjiang 212003 P. R. China
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28
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Structural Controls of Tetraphenylbenzene-based AIEgens for Non-doped Deep Blue Organic Light-emitting Diodes. Chem Res Chin Univ 2021. [DOI: 10.1007/s40242-021-0403-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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29
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Gunawardana HDCN, Osada K, Koswattage KR, Noguchi Y. Enhancement of the molecular orientation of TPBi in coevaporated films of UGH‐2 host molecules. SURF INTERFACE ANAL 2021. [DOI: 10.1002/sia.6933] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
| | - Kohei Osada
- School of Science & Technology Meiji University Kawasaki Japan
| | | | - Yutaka Noguchi
- School of Science & Technology Meiji University Kawasaki Japan
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30
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Schmid M, Harms K, Degitz C, Morgenstern T, Hofmann A, Friederich P, Johannes HH, Wenzel W, Kowalsky W, Brütting W. Optical and Electrical Measurements Reveal the Orientation Mechanism of Homoleptic Iridium-Carbene Complexes. ACS APPLIED MATERIALS & INTERFACES 2020; 12:51709-51718. [PMID: 33164497 DOI: 10.1021/acsami.0c14613] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Understanding and controlling the driving forces for molecular alignment in optoelectronic thin-film devices is of crucial importance for improving their performance. In this context, the preferential orientation of organometallic iridium complexes is in the focus of research to benefit from their improved light-outcoupling efficiencies in organic light-emitting diodes (OLEDs). Although there has been great progress concerning the orientation behavior for heteroleptic Ir complexes, the mechanism behind the alignment of homoleptic complexes is still unclear yet. In this work, we present a sky-blue phosphorescent dye that shows variable alignment depending on systematic modifications of the ligands bound to the central iridium atom. From an optical study of the transition dipole moment orientation and the electrically accessible alignment of the permanent dipole moment, we conclude that the film morphology is related to both the aspect ratio of the dye and the local electrostatic interaction of the ligands with the film surface during growth. These results indicate a potential strategy to actively control the orientation of iridium-based emitters for the application in OLEDs.
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Affiliation(s)
- Markus Schmid
- Institute of Physics, University of Augsburg, 86135 Augsburg, Germany
| | - Kristoffer Harms
- Applied Organic Materials, Institute for High Frequency Technology, Technical University of Braunschweig, 38106 Braunschweig, Germany
| | - Carl Degitz
- Institute of Nanotechnology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
- Merck KGaA, Performance Materials - Display Solutions, Frankfurter Straße 250, 64293 Darmstadt, Germany
| | | | - Alexander Hofmann
- Institute of Physics, University of Augsburg, 86135 Augsburg, Germany
| | - Pascal Friederich
- Institute of Nanotechnology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
- Institute of Theoretical Informatics, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - Hans-Hermann Johannes
- Applied Organic Materials, Institute for High Frequency Technology, Technical University of Braunschweig, 38106 Braunschweig, Germany
| | - Wolfgang Wenzel
- Institute of Nanotechnology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany
| | - Wolfgang Kowalsky
- Applied Organic Materials, Institute for High Frequency Technology, Technical University of Braunschweig, 38106 Braunschweig, Germany
| | - Wolfgang Brütting
- Institute of Physics, University of Augsburg, 86135 Augsburg, Germany
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31
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Kim J, Hou S, Zhao H, Forrest SR. Nanoscale Mapping of Morphology of Organic Thin Films. NANO LETTERS 2020; 20:8290-8297. [PMID: 33135904 DOI: 10.1021/acs.nanolett.0c03440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We determine precise nanoscale information about the morphologies of several organic thin film structures using Fourier plane imaging microscopy (FIM). We used FIM microscopy to detect the orientation of molecular transition dipole moments from an extremely low density of luminescent dye molecules, which we call "morphology sensors". The orientation of the sensor molecules is driven by the local film structure and thus can be used to determine details of the host morphology without influencing it. We use symmetric planar phosphorescent dye molecules as the sensors that are deposited into the bulk of organic film hosts during the growth. We demonstrate morphological mapping with a depth resolution to a few Ångstroms that is limited by the ability to determine thickness during deposition, along with an in-plane resolution limited by optical diffraction. Furthermore, we monitor morphological changes arising from thermal annealing of metastable organic films that are commonly employed in photonic devices.
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Affiliation(s)
- Jongchan Kim
- Department of Electrical & Computer Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Shaocong Hou
- Department of Electrical & Computer Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Haonan Zhao
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Stephen R Forrest
- Department of Electrical & Computer Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department of Materials Science & Engineering, University of Michigan, Ann Arbor, Michigan 48109, United States
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32
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Xiang Y, Li P, Gong S, Huang YH, Wang CY, Zhong C, Zeng W, Chen Z, Lee WK, Yin X, Wu CC, Yang C. Acceptor plane expansion enhances horizontal orientation of thermally activated delayed fluorescence emitters. SCIENCE ADVANCES 2020; 6:6/41/eaba7855. [PMID: 33036963 PMCID: PMC7546701 DOI: 10.1126/sciadv.aba7855] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 08/21/2020] [Indexed: 05/26/2023]
Abstract
Manipulating orientation of organic emitters remains a formidable challenge in organic light-emitting diodes (OLEDs). Here, expansion of the acceptor plane of thermally activated delayed fluorescence (TADF) emitters was demonstrated to selectively modulate emitting dipole orientation. Two proof-of-the-concept molecules, PXZPyPM and PXZTAZPM, were prepared by introducing a planar 2-phenylpyridine or 2,4,6-triphenyl-1,3,5-triazine substituent into a prototypical molecule (PXZPM) bearing a pyrimidine core and two phenoxazine donors. This design approach suppressed the influence of substituents on electronic structures and associated optoelectronic properties. Accordingly, PXZPyPM and PXZTAZPM preserved almost the same excited states and similar emission characteristics as PXZPM. The expanded acceptor plane of PXZPyPM and PXZTAZPM resulted in a 15 to 18% increase in horizontal ratios of emitting dipole orientation. PXZPyPM supported its green device exhibiting an external quantum efficiency of 33.9% and a power efficiency of 118.9 lumen per watt, competitive with the most efficient green TADF OLEDs reported so far.
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Affiliation(s)
- Yepeng Xiang
- Department of Chemistry, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Wuhan University, Wuhan 430072, P. R. China
- Shenzhen Key Laboratory of Polymer Science and Technology, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, P. R. China
| | - Pan Li
- Department of Electrical Engineering, Graduate Institute of Electronics Engineering and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan
| | - Shaolong Gong
- Department of Chemistry, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Wuhan University, Wuhan 430072, P. R. China.
| | - Yu-Hsin Huang
- Department of Electrical Engineering, Graduate Institute of Electronics Engineering and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan
| | - Chun-Yu Wang
- Department of Electrical Engineering, Graduate Institute of Electronics Engineering and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan
| | - Cheng Zhong
- Department of Chemistry, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Wuhan University, Wuhan 430072, P. R. China
| | - Weixuan Zeng
- Department of Chemistry, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Wuhan University, Wuhan 430072, P. R. China
| | - Zhanxiang Chen
- Department of Chemistry, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Wuhan University, Wuhan 430072, P. R. China
| | - Wei-Kai Lee
- Department of Electrical Engineering, Graduate Institute of Electronics Engineering and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan
| | - Xiaojun Yin
- Shenzhen Key Laboratory of Polymer Science and Technology, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, P. R. China
| | - Chung-Chih Wu
- Department of Electrical Engineering, Graduate Institute of Electronics Engineering and Graduate Institute of Photonics and Optoelectronics, National Taiwan University, Taipei 10617, Taiwan.
| | - Chuluo Yang
- Department of Chemistry, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Wuhan University, Wuhan 430072, P. R. China.
- Shenzhen Key Laboratory of Polymer Science and Technology, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, P. R. China
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33
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Tang MC, Li LK, Lai SL, Cheung WL, Ng M, Wong CY, Chan MY, Yam VWW. Design Strategy Towards Horizontally Oriented Luminescent Tetradentate-Ligand-Containing Gold(III) Systems. Angew Chem Int Ed Engl 2020; 59:21023-21031. [PMID: 32754992 DOI: 10.1002/anie.202006911] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Indexed: 11/08/2022]
Abstract
Phosphorescent dopants are promising candidates for organic light-emitting diodes (OLEDs). Although it has been established that the out-coupling efficiency and overall performances of vacuum-deposited OLEDs can be significantly improved by a horizontal orientation of the dopants, no horizontally oriented gold(III) complexes have been reported to date. Herein, a novel class of tetradentate C^C^N^N ligand-containing gold(III) complexes with a preferential horizontal orientation successfully generated through a one-pot reaction is reported. These complexes demonstrate high photoluminescence quantum yields of 70 % and a high horizontal dipole ratio of 0.87 in solid-state thin films. Green-emitting OLEDs based on these complexes operate with a maximum external quantum efficiency of 20.6 % with an estimated out-coupling efficiency of around 30 %. A promising device stability has been achieved in the vacuum-deposited OLEDs, with operational half-lifetimes of around 37 500 h at 100 cd m-2 .
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Affiliation(s)
- Man-Chung Tang
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. China
| | - Lok-Kwan Li
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. China
| | - Shiu-Lun Lai
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. China
| | - Wai-Lung Cheung
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. China
| | - Maggie Ng
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. China
| | - Chun-Yin Wong
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. China
| | - Mei-Yee Chan
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. China
| | - Vivian Wing-Wah Yam
- Institute of Molecular Functional Materials and Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. China
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34
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Tang M, Li L, Lai S, Cheung W, Ng M, Wong C, Chan M, Yam VW. Design Strategy Towards Horizontally Oriented Luminescent Tetradentate‐Ligand‐Containing Gold(III) Systems. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202006911] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Man‐Chung Tang
- Institute of Molecular Functional Materials and Department of Chemistry The University of Hong Kong Pokfulam Road Hong Kong P. R. China
| | - Lok‐Kwan Li
- Institute of Molecular Functional Materials and Department of Chemistry The University of Hong Kong Pokfulam Road Hong Kong P. R. China
| | - Shiu‐Lun Lai
- Institute of Molecular Functional Materials and Department of Chemistry The University of Hong Kong Pokfulam Road Hong Kong P. R. China
| | - Wai‐Lung Cheung
- Institute of Molecular Functional Materials and Department of Chemistry The University of Hong Kong Pokfulam Road Hong Kong P. R. China
| | - Maggie Ng
- Institute of Molecular Functional Materials and Department of Chemistry The University of Hong Kong Pokfulam Road Hong Kong P. R. China
| | - Chun‐Yin Wong
- Institute of Molecular Functional Materials and Department of Chemistry The University of Hong Kong Pokfulam Road Hong Kong P. R. China
| | - Mei‐Yee Chan
- Institute of Molecular Functional Materials and Department of Chemistry The University of Hong Kong Pokfulam Road Hong Kong P. R. China
| | - Vivian Wing‐Wah Yam
- Institute of Molecular Functional Materials and Department of Chemistry The University of Hong Kong Pokfulam Road Hong Kong P. R. China
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35
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Wang D, Ma Z, Wang N, Li C, Wang T, Liang Y, Zhang Z. Synthesis of 7-hydroxy-6H-naphtho[2,3-c]coumarin via a TsOH-mediated tandem reaction. Chem Commun (Camb) 2020; 56:10369-10372. [PMID: 32766650 DOI: 10.1039/d0cc04452k] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A concise and efficient method for the synthesis of 7-hydroxy-6H-naphtho[2,3-c]coumarin using available 1-(2-hydroxyphenyl)-2-phenylethanone and Meldrum's acid has been developed. This transformation involved a tandem aldol reaction/lactonization/Friedel-Crafts reaction to form a lactone ring and a benzene ring. It showed high atom economy with water and acetone as the byproducts. Mechanism studies demonstrated two roles of Meldrum's acid: (i) as the reagent for the tandem reaction, and (ii) as the catalyst for the Friedel-Crafts reaction. Moreover, the hydroxyl group of 7-hydroxy-6H-naphtho[2,3-c]coumarin was further functionalized efficiently by arylethynyl, aryl, and cyano groups to furnish D-π-A compounds with excellent fluorescence emissions (ΦF = 0.14-0.78).
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Affiliation(s)
- Ding Wang
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in Northwest of China, School of Chemistry and Chemical Engineering, and Basic Experimental Teaching Center, Shaanxi Normal University, Xi'an 710119, China.
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36
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Lee T, Sanzogni AV, Burn PL, Mark AE. Evolution and Morphology of Thin Films Formed by Solvent Evaporation: An Organic Semiconductor Case Study. ACS APPLIED MATERIALS & INTERFACES 2020; 12:40548-40557. [PMID: 32844643 DOI: 10.1021/acsami.0c08454] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The crucial role played by the solution-vapor interface in determining the growth and morphology of an organic semiconductor thin film formed by solvent evaporation has been examined in atomic detail. Specifically, how the loss of individual solvent molecules from the surface of the solution induces solute assembly has been studied using molecular dynamics simulations. The system consisted of bis(2-phenylpyridine) (acetylacetonate)iridium(III) [Ir(ppy)2(acac)] and 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP) in chloroform at 310 K. The simulations clearly indicate that (a) the system does not undergo uniform phase separation (spinodal decomposition), (b) solute aggregation initiates at the solution-vapor interface, (c) the distribution of solvent in the film is nonhomogeneous, (d) this nonhomogeneous distribution can induce preferential alignment of host molecules, and (e) a portion of the solvent likely remains trapped within the film. The work not only demonstrates the ability to directly model evaporation in atomic detail on the relevant length scales but also shows that atomistic simulations have the potential to shed new light on morphological properties of a wide range of organic semiconductor devices manufactured using solution-processing methods.
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Affiliation(s)
- Thomas Lee
- School of Chemistry & Molecular Biosciences, The University of Queensland, St. Lucia Campus, Brisbane 4072, Australia
- Centre for Organic Photonics & Electronics, The University of Queensland, St. Lucia Campus, Brisbane 4072, Australia
| | - Audrey V Sanzogni
- School of Chemistry & Molecular Biosciences, The University of Queensland, St. Lucia Campus, Brisbane 4072, Australia
- Centre for Organic Photonics & Electronics, The University of Queensland, St. Lucia Campus, Brisbane 4072, Australia
| | - Paul L Burn
- School of Chemistry & Molecular Biosciences, The University of Queensland, St. Lucia Campus, Brisbane 4072, Australia
- Centre for Organic Photonics & Electronics, The University of Queensland, St. Lucia Campus, Brisbane 4072, Australia
| | - Alan E Mark
- School of Chemistry & Molecular Biosciences, The University of Queensland, St. Lucia Campus, Brisbane 4072, Australia
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37
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Naqvi BA, Schmid M, Crovini E, Sahay P, Naujoks T, Rodella F, Zhang Z, Strohriegl P, Bräse S, Zysman-Colman E, Brütting W. What Controls the Orientation of TADF Emitters? Front Chem 2020; 8:750. [PMID: 33102430 PMCID: PMC7500207 DOI: 10.3389/fchem.2020.00750] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 07/21/2020] [Indexed: 11/13/2022] Open
Abstract
Thermally-activated delayed fluorescence (TADF) emitters—just like phosphorescent ones—can in principle allow for 100% internal quantum efficiency of organic light-emitting diodes (OLEDs), because the initially formed electron-hole pairs in the non-emissive triplet state can be efficiently converted into emissive singlets by reverse intersystem crossing. However, as compared to phosphorescent emitter complexes with their bulky—often close to spherical—molecular structures, TADF emitters offer the advantage to align them such that their optical transition dipole moments (TDMs) lie preferentially in the film plane. In this report, we address the question which factors control the orientation of TADF emitters. Specifically, we discuss how guest-host interactions may be used to influence this parameter and propose an interplay of different factors being responsible. We infer that emitter orientation is mainly governed by the molecular shape of the TADF molecule itself and by the physical properties of the host—foremost, its glass transition temperature Tg and its tendency for alignment being expressed, e.g., as birefringence or the formation of a giant surface potential of the host. Electrostatic dipole-dipole interactions between host and emitter are not found to play an important role.
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Affiliation(s)
- Bilal A Naqvi
- Institute of Physics, University of Augsburg, Augsburg, Germany
| | - Markus Schmid
- Institute of Physics, University of Augsburg, Augsburg, Germany
| | - Ettore Crovini
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, United Kingdom
| | - Prakhar Sahay
- Institute of Physics, University of Augsburg, Augsburg, Germany
| | - Tassilo Naujoks
- Institute of Physics, University of Augsburg, Augsburg, Germany
| | | | - Zhen Zhang
- Institute of Organic Chemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Peter Strohriegl
- Macromolecular Chemistry, University of Bayreuth, Bayreuth, Germany
| | - Stefan Bräse
- Institute of Organic Chemistry, Karlsruhe Institute of Technology, Karlsruhe, Germany.,Institute of Biological and Chemical Systems - Functional Molecular Systems, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Eli Zysman-Colman
- Organic Semiconductor Centre, EaStCHEM School of Chemistry, University of St Andrews, St Andrews, United Kingdom
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38
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Electronic structure and photophysics of a supermolecular iron complex having a long MLCT-state lifetime and panchromatic absorption. Proc Natl Acad Sci U S A 2020; 117:20430-20437. [PMID: 32788361 PMCID: PMC7456135 DOI: 10.1073/pnas.2009996117] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The main hurdle that prevents earth-abundant iron-based complexes from replacing environmentally unfriendly and expensive heavy metal [e.g., Ru(II), Os(II), Ir(III)] complexes in solar-energy conversion applications is the typical ultrashort (femtosecond timescale) charge-transfer state lifetime of Fe(II) chromophores. We provide a design roadmap to a generation of efficient iron-based photosensitizers and present an Fe(II) complex archetype, FeNHCPZn, which features a profoundly extended metal-to-ligand charge-transfer (3MLCT) lifetime and a large transition-dipole moment difference between its ground and metal-to-ligand charge-transfer states. This supermolecular design promotes superior visible photon harvesting over classic metal complexes while assuring a triplet excited-state oxidation potential appropriate for charge injection into the conduction bands of common semiconductor electrode materials, highlighting its photosensitizing utility in dye-sensitized solar-cell architectures. Exploiting earth-abundant iron-based metal complexes as high-performance photosensitizers demands long-lived electronically excited metal-to-ligand charge-transfer (MLCT) states, but these species suffer typically from femtosecond timescale charge-transfer (CT)-state quenching by low-lying nonreactive metal-centered (MC) states. Here, we engineer supermolecular Fe(II) chromophores based on the bis(tridentate-ligand)metal(II)-ethyne-(porphinato)zinc(II) conjugated framework, previously shown to give rise to highly delocalized low-lying 3MLCT states for other Group VIII metal (Ru, Os) complexes. Electronic spectral, potentiometric, and ultrafast pump–probe transient dynamical data demonstrate that a combination of a strong σ-donating tridentate ligand and a (porphinato)zinc(II) moiety with low-lying π*-energy levels, sufficiently destabilize MC states and stabilize supermolecular MLCT states to realize Fe(II) complexes that express 3MLCT state photophysics reminiscent of their heavy-metal analogs. The resulting Fe(II) chromophore archetype, FeNHCPZn, features a highly polarized CT state having a profoundly extended 3MLCT lifetime (160 ps), 3MLCT phosphorescence, and ambient environment stability. Density functional and domain-based local pair natural orbital coupled cluster [DLPNO-CCSD(T)] theory reveal triplet-state wavefunction spatial distributions consistent with electronic spectroscopic and excited-state dynamical data, further underscoring the dramatic Fe metal-to-extended ligand CT character of electronically excited FeNHCPZn. This design further prompts intense panchromatic absorptivity via redistributing high-energy absorptive oscillator strength throughout the visible spectral domain, while maintaining a substantial excited-state oxidation potential for wide-ranging photochemistry––highlighted by the ability of FeNHCPZn to photoinject charges into a SnO2/FTO electrode in a dye-sensitized solar cell (DSSC) architecture. Concepts enumerated herein afford opportunities for replacing traditional rare-metal–based emitters for solar-energy conversion and photoluminescence applications.
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Bhattacharyya D, Dhar P, Liu Y, Djurovich PI, Thompson ME, Benderskii AV. Vibrational Sum Frequency Generation Study of the Interference Effect on a Thin Film of 4,4'-Bis( N-carbazolyl)-1,1'-biphenyl (CBP) and Its Interfacial Orientation. ACS APPLIED MATERIALS & INTERFACES 2020; 12:26515-26524. [PMID: 32406227 DOI: 10.1021/acsami.0c01394] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Molecular organization of vapor-deposited organic molecules in the active layer of organic light-emitting diodes (OLEDs) has been a matter of great interest as it directly influences various optoelectronic properties and the overall performance of the devices. Contrary to the general assumption of isotropic molecular orientation in vacuum-deposited thin-film OLEDs, it is possible to achieve an anisotropic molecular distribution at or near the surface under controlled experimental conditions. In this study, we have used interface-specific vibrational sum frequency generation (VSFG) spectroscopy to determine the orientation of a low-molecular weight OLED material, 4,4'-bis(N-carbazolyl)-1,1'-biphenyl (CBP), at free (air) and buried (CaF2) interfaces. VSFG spectra were measured at four different polarization combinations for five different thicknesses of the CBP film. The spectral shift and VSFG intensity changes with the film thickness can be accurately modeled by considering the optical interference effect of the signals coming from the CBP/air and CBP/CaF2 interfaces. A global fitting of the experimental spectra for all thicknesses along with theoretical simulations reveal that the long molecular axis of CBP is oriented at an angle of ∼58° (47-70°) from the surface normal at the air/CBP interface, whereas at the CBP/CaF2 interface, the angle is ∼48° (43-52°). Such a change in the angle (∼10°) suggests that the CBP molecule tends to orient more vertically (edge-on) at the buried CaF2 interface, which may be attributed to the intermolecular π-π stacking interaction between adjacent CBP molecules.
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Affiliation(s)
- Dhritiman Bhattacharyya
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| | - Purnim Dhar
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| | - Yifei Liu
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| | - Peter I Djurovich
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| | - Mark E Thompson
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| | - Alexander V Benderskii
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
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40
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Tanaka Y, Matsuura N, Ishii H. Self-Assembled Electret for Vibration-Based Power Generator. Sci Rep 2020; 10:6648. [PMID: 32313082 PMCID: PMC7170925 DOI: 10.1038/s41598-020-63484-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 04/01/2020] [Indexed: 11/11/2022] Open
Abstract
The vibration-based electret generators (EGs) for energy harvesting have been extensively studied because they can obtain electrical energy from ambient vibrations. EGs exhibit a sandwich structure of electrodes surrounding an air gap and an electret, which is a dielectric material with a quasi-permanent electrical charge or dipole polarisation. Various charging processes have been developed because the surface charge density (σ) of the electret determines the output power of the device. However, such processes are considered to constitute a key productivity-limiting factor from the mass production viewpoint, making their simplification or elimination a highly desired objective. Herein, a model EG that does not require any charging process by utilising the spontaneous orientation polarisation of 1,3,5-tris(1-phenyl-1H-benzimidazole-2-yl)benzene (TPBi) is demonstrated. The surface potential (Vsp) of an evaporated TPBi film has reached 30.2 V at a film thickness of 500 nm without using a charging process. The estimated σ of 1.7 mC m−2 is comparable with that obtained using a conventional polymer-based electret after charging. Furthermore, Vsp is considerably stable in environmental conditions; thus, TPBi can be considered to be “self-assembled” electret (SAE). Application of SAE leads to developing an EG without requiring the charging process.
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Affiliation(s)
- Yuya Tanaka
- Center for Frontier Science, Chiba University, Chiba, 263-8522, Japan. .,Graduate School of Science and Engineering, Chiba University, Chiba, 263-8522, Japan. .,Japan Science and Technology Agency, PRESTO, Saitama, 332-0012, Japan.
| | - Noritaka Matsuura
- Graduate School of Science and Engineering, Chiba University, Chiba, 263-8522, Japan
| | - Hisao Ishii
- Center for Frontier Science, Chiba University, Chiba, 263-8522, Japan.,Graduate School of Science and Engineering, Chiba University, Chiba, 263-8522, Japan.,Molecular Chirality Research Center, Chiba University, Chiba, 263-8522, Japan
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41
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Zhang X, Cao Y, Song J, Li K, Jiang Q, Yuan A, Shi C. A New Facial Homoleptic Tris‐cyclometalated Iridium(III) Complex with Oxygen‐bridged Triarylamine Units. ChemistrySelect 2020. [DOI: 10.1002/slct.202000681] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Xinghua Zhang
- School of Environmental and Chemical EngineeringJiangsu University of Science and Technology Zhenjiang 212003, P. R. China
| | - Yibo Cao
- School of Environmental and Chemical EngineeringJiangsu University of Science and Technology Zhenjiang 212003, P. R. China
| | - Jialiang Song
- School of Environmental and Chemical EngineeringJiangsu University of Science and Technology Zhenjiang 212003, P. R. China
| | - Kang Li
- School of Environmental and Chemical EngineeringJiangsu University of Science and Technology Zhenjiang 212003, P. R. China
| | - Qibin Jiang
- School of Environmental and Chemical EngineeringJiangsu University of Science and Technology Zhenjiang 212003, P. R. China
| | - Aihua Yuan
- School of Environmental and Chemical EngineeringJiangsu University of Science and Technology Zhenjiang 212003, P. R. China
| | - Chao Shi
- School of Environmental and Chemical EngineeringJiangsu University of Science and Technology Zhenjiang 212003, P. R. China
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Wu X, Chen DG, Liu D, Liu SH, Shen SW, Wu CI, Xie G, Zhou J, Huang ZX, Huang CY, Su SJ, Zhu W, Chou PT. Highly Emissive Dinuclear Platinum(III) Complexes. J Am Chem Soc 2020; 142:7469-7479. [DOI: 10.1021/jacs.9b13956] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Xiugang Wu
- School of Materials Science and Engineering, Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering, Jiangsu Engineering Laboratory of Light-Electricity-Heat Energy-Converting Materials and Applications, Jiangsu Key Laboratories of Environment-Friendly Polymers, National Experimental Demonstration Center for Materials Science and Engineering, Changzhou University, Changzhou 213164, China
| | | | - Denghui Liu
- School of Materials Science and Engineering, Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering, Jiangsu Engineering Laboratory of Light-Electricity-Heat Energy-Converting Materials and Applications, Jiangsu Key Laboratories of Environment-Friendly Polymers, National Experimental Demonstration Center for Materials Science and Engineering, Changzhou University, Changzhou 213164, China
| | | | | | | | - Guohua Xie
- Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Hubei Key Lab on Organic and Polymeric Optoelectronic Materials, Department of Chemistry, Wuhan University, Wuhan 430072, China
| | - Jianwei Zhou
- School of Materials Science and Engineering, Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering, Jiangsu Engineering Laboratory of Light-Electricity-Heat Energy-Converting Materials and Applications, Jiangsu Key Laboratories of Environment-Friendly Polymers, National Experimental Demonstration Center for Materials Science and Engineering, Changzhou University, Changzhou 213164, China
| | | | | | - Shi-Jian Su
- Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou 510640, China
| | - Weiguo Zhu
- School of Materials Science and Engineering, Jiangsu Collaborative Innovation Center of Photovoltaic Science and Engineering, Jiangsu Engineering Laboratory of Light-Electricity-Heat Energy-Converting Materials and Applications, Jiangsu Key Laboratories of Environment-Friendly Polymers, National Experimental Demonstration Center for Materials Science and Engineering, Changzhou University, Changzhou 213164, China
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43
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Ban X, Chen F, Pan J, Liu Y, Zhu A, Jiang W, Sun Y. Exciplex Formation and Electromer Blocking for Highly Efficient Blue Thermally Activated Delayed Fluorescence OLEDs with All-Solution-Processed Organic Layers. Chemistry 2020; 26:3090-3102. [PMID: 31837285 DOI: 10.1002/chem.201904415] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 12/01/2019] [Indexed: 11/08/2022]
Abstract
Highly efficient solution-processable emitters are greatly desired to develop low-cost organic light-emitting diodes (OLEDs). The recently developed thermally activated delayed fluorescence (TADF) materials are promising candidates, but blue TADF materials compatible with the all-solution-process have still not been achieved. Here, a series of TADF materials, named X-4CzCN, are developed by introducing the bulky units through an unconjugated linker, which realizes high molecular weight to enhance the solvent resistance ability without disturbing the blue TADF feature. Meanwhile, the peripheral wrapping groups efficiently inhibit the triplet-triplet and triplet-polaron quenching by isolating the energy-transfer and charge-transporting channels. The photophysical measurements indicate that a small variation in peripheral unit will have a noticeable effect on the luminescence efficiency. The enlarged volume of peripheral units will make the electroluminescent spectra blueshift, while enhancing the energy transfer of exciplex and blocking the energy leakage of electromer can facilitate the exciton utilization. As a result, the fully solution-processed blue OLED achieves a CIE of (0.16, 0.27), a low turn on voltage of 2.9 eV, and a high external quantum efficiency of 20.6 %. As far as we known, this is the first report of all-solution-processed TADF OLEDs with blue emission, which exhibits a high efficiency even comparable to the vacuum-deposited devices.
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Affiliation(s)
- Xinxin Ban
- Jiangsu Key Laboratory of Function Control Technology for, Advanced Materials, School of Chemical Engineering, Jiangsu Ocean University, Jiangsu, 222005, P. R. China.,School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 211189, P. R. China
| | - Feng Chen
- Jiangsu Key Laboratory of Function Control Technology for, Advanced Materials, School of Chemical Engineering, Jiangsu Ocean University, Jiangsu, 222005, P. R. China
| | - Jie Pan
- Jiangsu Key Laboratory of Function Control Technology for, Advanced Materials, School of Chemical Engineering, Jiangsu Ocean University, Jiangsu, 222005, P. R. China
| | - Yan Liu
- Jiangsu Key Laboratory of Function Control Technology for, Advanced Materials, School of Chemical Engineering, Jiangsu Ocean University, Jiangsu, 222005, P. R. China
| | - Aiyun Zhu
- Jiangsu Key Laboratory of Function Control Technology for, Advanced Materials, School of Chemical Engineering, Jiangsu Ocean University, Jiangsu, 222005, P. R. China
| | - Wei Jiang
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 211189, P. R. China
| | - Yueming Sun
- School of Chemistry and Chemical Engineering, Southeast University, Nanjing, 211189, P. R. China
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44
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Kang GJ, Cheng HY, Li K, Ma JF, Ren XF. Effect of diphenylamine substitution on color tuning and charge transfer of a series of Pt(Ⅱ) complexes for red emitters: A Theoretical study. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2019.137077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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45
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Bronstein H, Nielsen CB, Schroeder BC, McCulloch I. The role of chemical design in the performance of organic semiconductors. Nat Rev Chem 2020; 4:66-77. [PMID: 37128048 DOI: 10.1038/s41570-019-0152-9] [Citation(s) in RCA: 226] [Impact Index Per Article: 56.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/14/2019] [Indexed: 12/15/2022]
Abstract
Organic semiconductors are solution-processable, lightweight and flexible and are increasingly being used as the active layer in a wide range of new technologies. The versatility of synthetic organic chemistry enables the materials to be tuned such that they can be incorporated into biological sensors, wearable electronics, photovoltaics and flexible displays. These devices can be improved by improving their material components, not only by developing the synthetic chemistry but also by improving the analytical and computational techniques that enable us to understand the factors that govern material properties. Judicious molecular design provides control of the semiconductor frontier molecular orbital energy distribution and guides the hierarchical assembly of organic semiconductors into functional films where we can manipulate the properties and motion of charges and excited states. This Review describes how molecular design plays an integral role in developing organic semiconductors for electronic devices in present and emerging technologies.
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Affiliation(s)
- Hugo Bronstein
- Department of Chemistry, University of Cambridge, Cambridge, UK
| | - Christian B Nielsen
- School of Biological and Chemical Sciences, Queen Mary University of London, London, UK
| | - Bob C Schroeder
- Department of Chemistry, University College London, London, UK
| | - Iain McCulloch
- Department of Chemistry, Imperial College London, London, UK.
- King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), Physical Sciences and Engineering Division (PSE), Material Science and Engineering Program (MSE), Thuwal, Saudi Arabia.
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46
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Ban X, Liu Y, Pan J, Chen F, Zhu A, Jiang W, Sun Y, Dong Y. Design of Blue Thermally Activated Delayed Fluorescent Emitter with Efficient Exciton Gathering Property for High-Performance Fully Solution-Processed Hybrid White OLEDs. ACS APPLIED MATERIALS & INTERFACES 2020; 12:1190-1200. [PMID: 31840975 DOI: 10.1021/acsami.9b20903] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The blue thermally activated delay fluorescence (TADF) emitters are highly attractive in the fields of constructing hybrid white organic light-emitting diodes (WOLEDs) due to its high efficiency and color stability. However, few blue TADF emitters can withstand sequential orthogonal solvents, making it impossible to fabricate the fully solution-processed hybrid WOLEDs. Here, two TADF materials, PCz-4CzCN and TPA-4CzCN, were designed and synthesized by equipping the emissive core with nonconjugated bulky units, which can effectively enhance the solvent resistance ability without disturbing the TADF feature. The photophysical investigation indicates that phenylcarbazole unit can efficiently block the electromer formation to enhance the energy transfer and exciton utilization of the emitter. Accordingly, the blue OLEDs of PCz-4CzCN shows higher external quantum efficiency (EQE) of 22.6%, which is the best performance recorded among the fully solution-processed blue OLEDs. Upon further doping, the yellow phosphor PO-01, the fully solution-processed TADF-phosphor (T-P) hybrid WOLEDs was successfully obtained with high performance for the first time. Thanks to the efficient exciplex formation, the turn-on voltage of the white device is only 2.8 V, and the maximum brightness and power efficiency are as high as 53 300 cd m-2 and 38.5 lm W-1, respectively, which are even higher than the previous reported T-P hybrid WOLEDs with a vacuum-deposited electron transfer layer.
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Affiliation(s)
- Xinxin Ban
- Jiangsu Key Laboratory of Function Control Technology for Advanced Materials, School of Chemical Engineering , Jiangsu Ocean University , Lianyungang , Jiangsu 222005 , China
| | - Yan Liu
- Jiangsu Key Laboratory of Function Control Technology for Advanced Materials, School of Chemical Engineering , Jiangsu Ocean University , Lianyungang , Jiangsu 222005 , China
| | - Jie Pan
- Jiangsu Key Laboratory of Function Control Technology for Advanced Materials, School of Chemical Engineering , Jiangsu Ocean University , Lianyungang , Jiangsu 222005 , China
| | - Feng Chen
- Jiangsu Key Laboratory of Function Control Technology for Advanced Materials, School of Chemical Engineering , Jiangsu Ocean University , Lianyungang , Jiangsu 222005 , China
| | - Aiyun Zhu
- Jiangsu Key Laboratory of Function Control Technology for Advanced Materials, School of Chemical Engineering , Jiangsu Ocean University , Lianyungang , Jiangsu 222005 , China
| | - Wei Jiang
- School of Chemistry and Chemical Engineering , Southeast University , Nanjing , Jiangsu 211189 , China
| | - Yueming Sun
- School of Chemistry and Chemical Engineering , Southeast University , Nanjing , Jiangsu 211189 , China
| | - Yajie Dong
- Nanoscience Technology Center , University of Central Florida , Orlando , Florida 32826 , United States
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47
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Boehm BJ, Nguyen HTL, Huang DM. The interplay of interfaces, supramolecular assembly, and electronics in organic semiconductors. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:423001. [PMID: 31212263 DOI: 10.1088/1361-648x/ab2ac2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Organic semiconductors, which include a diverse range of carbon-based small molecules and polymers with interesting optoelectronic properties, offer many advantages over conventional inorganic semiconductors such as silicon and are growing in importance in electronic applications. Although these materials are now the basis of a lucrative industry in electronic displays, many promising applications such as photovoltaics remain largely untapped. One major impediment to more rapid development and widespread adoption of organic semiconductor technologies is that device performance is not easily predicted from the chemical structure of the constituent molecules. Fundamentally, this is because organic semiconductor molecules, unlike inorganic materials, interact by weak non-covalent forces, resulting in significant structural disorder that can strongly impact electronic properties. Nevertheless, directional forces between generally anisotropic organic-semiconductor molecules, combined with translational symmetry breaking at interfaces, can be exploited to control supramolecular order and consequent electronic properties in these materials. This review surveys recent advances in understanding of supramolecular assembly at organic-semiconductor interfaces and its impact on device properties in a number of applications, including transistors, light-emitting diodes, and photovoltaics. Recent progress and challenges in computer simulations of supramolecular assembly and orientational anisotropy at these interfaces is also addressed.
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Affiliation(s)
- Belinda J Boehm
- Department of Chemistry, School of Physical Sciences, The University of Adelaide, SA 5005, Australia
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48
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Kim J, Batagoda T, Lee J, Sylvinson D, Ding K, Saris PJG, Kaipa U, Oswald IWH, Omary MA, Thompson ME, Forrest SR. Systematic Control of the Orientation of Organic Phosphorescent Pt Complexes in Thin Films for Increased Optical Outcoupling. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1900921. [PMID: 31197907 DOI: 10.1002/adma.201900921] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 05/20/2019] [Indexed: 06/09/2023]
Abstract
Orienting light-emitting molecules relative to the substrate is an effective method to enhance the optical outcoupling of organic light-emitting devices. Platinum(II) phosphorescent complexes enable facile control of the molecular alignment due to their planar structures. Here, the orientation of Pt(II) complexes during the growth of emissive layers is controlled by two different methods: modifying the molecular structure and using structural templating. Molecules whose structures are modified by adjusting the diketonate ligand of the Pt complex, dibenzo-(f,h)quinoxaline Pt dipivaloylmethane, (dbx)Pt(dpm), show an ≈20% increased fraction of horizontally aligned transition dipole moments compared to (dbx)Pt(dpm) doped into a 4,4'-bis(N-carbazolyl)-1,1'-biphenyl, CBP, host. Alternatively, a template composed of highly ordered 3,4,9,10-perylenetetracarboxylic dianhydride monolayers is predeposited to drive the alignment of a subsequently deposited emissive layer comprising (2,3,7,8,12,13,17,18-octaethyl)-21H,23H-porphyrinplatinum(II) doped into triindolotriazine. This results in a 60% increase in horizontally aligned transition dipole moments compared to the film deposited in the absence of the template. The findings provide a systematic route for controlling molecular alignment during layer growth, and ultimately to increase the optical outcoupling in organic light-emitting diodes.
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Affiliation(s)
- Jongchan Kim
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, USA
| | - Thilini Batagoda
- Department of Chemistry, University of Southern California, Los Angeles, CA, USA
| | - Jaesang Lee
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, USA
| | - Daniel Sylvinson
- Department of Chemistry, University of Southern California, Los Angeles, CA, USA
| | - Kan Ding
- Departments of Physics and Materials Science and Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Patrick J G Saris
- Department of Chemistry, University of Southern California, Los Angeles, CA, USA
| | - Ushasree Kaipa
- Department of Chemistry, University of North Texas, Denton, TX, 76203, USA
| | - Iain W H Oswald
- Department of Chemistry, University of North Texas, Denton, TX, 76203, USA
| | - Mohammad A Omary
- Department of Chemistry, University of North Texas, Denton, TX, 76203, USA
| | - Mark E Thompson
- Department of Chemistry, University of Southern California, Los Angeles, CA, USA
| | - Stephen R Forrest
- Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, USA
- Departments of Physics and Materials Science and Engineering, University of Michigan, Ann Arbor, MI, USA
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49
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Solanki J, Surati K. Heteroleptic Zn(II) Complexes: Synthesis, Characterization and Photoluminescence Properties. J Fluoresc 2019; 29:865-875. [PMID: 31325009 DOI: 10.1007/s10895-019-02397-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Accepted: 05/28/2019] [Indexed: 10/26/2022]
Abstract
Heteroleptic Zn (II) complexes containing 8-hydroxy quinoline as preliminary ligand and pyrazolone based derivatives as secondary ligand were synthesized and their structures confirmed by NMR, Mass, FT-IR, UV-vis and Elemental analysis. Theses complexes show good photoluminescence properties in solid and solution state in the range of 505-544 nm with quantum yield 0.38 to 0.50. Whereas these complexes also show good life time in the range of 0.037 to 0.043 ms. These complexes show shift in the range of 25-30 nm. in different polar and nonpolar solvents due to intramolecular charge transfer (ICT). The bandgap of these complexes is around ~2.60 eV. Highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of all complexes are determine by cyclic voltammetry it obtained in the range of and ~ (-5.29 eV) and ~(-2.69 eV). The energy band gap, frontier molecular orbitals (FMO) energy levels and geometrical structures were optimized using density functional theory (DFT) with B3LYP/6-31G* basic set on Spartan'18 software. All complexes displayed high thermal stability. Graphical Abstract Donor-Bridge- Accepter (D-B-A) based Heteroleptic Zn(II) complexes for OLEDs application.
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Affiliation(s)
- Jaydip Solanki
- Department of Chemistry, Sardar Patel University, Vallabh Vidyanagar, Anand, Gujarat, 388120, India
| | - Kiran Surati
- Department of Chemistry, Sardar Patel University, Vallabh Vidyanagar, Anand, Gujarat, 388120, India.
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50
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Hartmann NF, Otten M, Fedin I, Talapin D, Cygorek M, Hawrylak P, Korkusinski M, Gray S, Hartschuh A, Ma X. Uniaxial transition dipole moments in semiconductor quantum rings caused by broken rotational symmetry. Nat Commun 2019; 10:3253. [PMID: 31332181 PMCID: PMC6646311 DOI: 10.1038/s41467-019-11225-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 06/17/2019] [Indexed: 11/10/2022] Open
Abstract
Semiconductor quantum rings are topological structures that support fascinating phenomena such as the Aharonov–Bohm effect and persistent current, which are of high relevance in the research of quantum information devices. The annular shape of quantum rings distinguishes them from other low-dimensional materials, and enables topologically induced properties such as geometry-dependent spin manipulation and emission. While optical transition dipole moments (TDMs) in zero to two-dimensional optical emitters have been well investigated, those in quantum rings remain obscure despite their utmost relevance to the quantum photonic applications of quantum rings. Here, we study the dimensionality and orientation of TDMs in CdSe quantum rings. In contrast to those in other two-dimensional optical emitters, we find that TDMs in CdSe quantum rings show a peculiar in-plane linear distribution. Our theoretical modeling reveals that this uniaxial TDM originates from broken rotational symmetry in the quantum ring geometries. Annular semiconductor structures, or “quantum rings”, are of interest for quantum information and photonics applications. Here, the authors show that breaking rotational symmetry through elongation generates an in-plane optical transition dipole moment in CdSe quantum rings.
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Affiliation(s)
- Nicolai F Hartmann
- Department of Chemistry and Center for NanoScience (CeNS), LMU Munich, 81377, Munich, Germany
| | - Matthew Otten
- Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Igor Fedin
- Department of Chemistry and James Franck Institute, University of Chicago, Chicago, IL, 60637, USA
| | - Dmitri Talapin
- Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL, 60439, USA.,Department of Chemistry and James Franck Institute, University of Chicago, Chicago, IL, 60637, USA
| | - Moritz Cygorek
- Department of Physics, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Pawel Hawrylak
- Department of Physics, University of Ottawa, Ottawa, ON, K1N 6N5, Canada
| | - Marek Korkusinski
- Quantum Theory Group, Security and Disruptive Technologies, National Research Council, Ottawa, K1A0R6, Canada
| | - Stephen Gray
- Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Achim Hartschuh
- Department of Chemistry and Center for NanoScience (CeNS), LMU Munich, 81377, Munich, Germany.
| | - Xuedan Ma
- Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL, 60439, USA.
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