1
|
Witt J, Mischok A, Tenopala Carmona F, Hillebrandt S, Butscher JF, Gather MC. High-Brightness Blue Polariton Organic Light-Emitting Diodes. ACS PHOTONICS 2024; 11:1844-1850. [PMID: 38766499 PMCID: PMC11100280 DOI: 10.1021/acsphotonics.3c01610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 03/28/2024] [Accepted: 04/10/2024] [Indexed: 05/22/2024]
Abstract
Polariton organic light-emitting diodes (POLEDs) use strong light-matter coupling as an additional degree of freedom to tailor device characteristics, thus making them ideal candidates for many applications, such as room temperature laser diodes and high-color purity displays. However, achieving efficient formation of and emission from exciton-polaritons in an electrically driven device remains challenging due to the need for strong absorption, which often induces significant nonradiative recombination. Here, we investigate a novel POLED architecture to achieve polariton formation and high-brightness light emission. We utilize the blue-fluorescent emitter material 4,4'-Bis(4-(9H-carbazol-9-yl)styryl)biphenyl (BSBCz), which exhibits strong absorption and a highly horizontal transition-dipole orientation as well as a high photoluminescence quantum efficiency, even at high doping concentrations. We achieve a peak luminance of over 20,000 cd/m2 and external quantum efficiencies of more than 2%. To the best of our knowledge, these values represent the highest reported so far for electrically driven polariton emission from an organic semiconductor emitting in the blue region of the spectrum. Our work therefore paves the way for a new generation of efficient and powerful optoelectronic devices based on POLEDs.
Collapse
Affiliation(s)
- Julia Witt
- Humboldt
Centre for Nano- and Biophotonics, Department of Chemistry, University of Cologne, Greinstr. 4-6, 50939 Cologne, Germany
| | - Andreas Mischok
- Humboldt
Centre for Nano- and Biophotonics, Department of Chemistry, University of Cologne, Greinstr. 4-6, 50939 Cologne, Germany
| | - Francisco Tenopala Carmona
- Humboldt
Centre for Nano- and Biophotonics, Department of Chemistry, University of Cologne, Greinstr. 4-6, 50939 Cologne, Germany
| | - Sabina Hillebrandt
- Humboldt
Centre for Nano- and Biophotonics, Department of Chemistry, University of Cologne, Greinstr. 4-6, 50939 Cologne, Germany
| | - Julian F. Butscher
- Humboldt
Centre for Nano- and Biophotonics, Department of Chemistry, University of Cologne, Greinstr. 4-6, 50939 Cologne, Germany
- Organic
Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS, United
Kingdom
| | - Malte C. Gather
- Humboldt
Centre for Nano- and Biophotonics, Department of Chemistry, University of Cologne, Greinstr. 4-6, 50939 Cologne, Germany
- Organic
Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS, United
Kingdom
| |
Collapse
|
2
|
Tang X, Xie M, Lin Z, Mitrofanov K, Tsagaantsooj T, Lee YT, Kabe R, Sandanayaka ASD, Matsushima T, Hatakeyama T, Adachi C. A Rigid Multiple Resonance Thermally Activated Delayed Fluorescence Core Toward Stable Electroluminescence and Lasing. Angew Chem Int Ed Engl 2024; 63:e202315210. [PMID: 37991245 DOI: 10.1002/anie.202315210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 11/08/2023] [Accepted: 11/20/2023] [Indexed: 11/23/2023]
Abstract
The investigation of organic light-emitting diodes (OLEDs) and organic laser devices with thermally activated delayed fluorescence (TADF) molecules is emerging due to the potential of harnessing triplets. In this work, a boron/nitrogen multiple-resonance TADF polycyclic framework fusing carbazole units (CzBNPh) was proposed. CzBNPh exhibited a narrowband emission (<30 nm), a unity photoluminescence quantum yield, and a fast radiative rate. Consequently, CzBNPh demonstrated a low distributed feedback (DFB) lasing threshold of 0.68 μJ cm-2 . Furthermore, the stimulated emission zone of CzBNPh was effectively separated from its singlet and triplet absorption, thereby minimizing the singlet-triplet annihilation under long-pulsed excitation ranging from 20 μs to 2.5 ms. Significantly, the enhanced rigid molecular conformation, thermal stability, and photo-stability resulted in improved lasing and electroluminescence stability compared to that of 5,9-diphenyl-5,9-diaza-13b-boranaphtho[3,2,1-de]anthracene (DABNA)-core. These findings indicate the potential of CzBN-core as a promising framework for achieving long-pulsed wave and electrically-pumped lasing in the future.
Collapse
Affiliation(s)
- Xun Tang
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
| | - Mingchen Xie
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
| | - Zesen Lin
- Organic Optoelectronics Unit, Okinawa Institute of Science and Technology, Graduate University, 1919-1 Tancha, Kunigami-gun, Okinawa, Onna-son, 904-0495, Japan
| | - Kirill Mitrofanov
- Organic Optoelectronics Unit, Okinawa Institute of Science and Technology, Graduate University, 1919-1 Tancha, Kunigami-gun, Okinawa, Onna-son, 904-0495, Japan
| | - Tuul Tsagaantsooj
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
| | - Yi-Ting Lee
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
- Department of Chemistry, Soochow University, 70 Linhsi Rd., Shihlin, Taipei, Taiwan
| | - Ryota Kabe
- Organic Optoelectronics Unit, Okinawa Institute of Science and Technology, Graduate University, 1919-1 Tancha, Kunigami-gun, Okinawa, Onna-son, 904-0495, Japan
| | - Atula S D Sandanayaka
- Department of Physical Sciences and Technologies, Faculty of Applied Sciences, Sabaragamuwa University of Sri Lanka, Belihuloya, 70140, Sri Lanka
| | - Toshinori Matsushima
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
| | - Takuji Hatakeyama
- Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan
| | - Chihaya Adachi
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
| |
Collapse
|
3
|
Kim D, Park HJ, Jung SH, Pyo WJ, Hassan SZ, Sim HR, Lee JH, Jee DW, Chung DS. Visible-Light Communication with Lighting: RGB Wavelength Division Multiplexing OLEDs/OPDs Platform. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2309416. [PMID: 37856894 DOI: 10.1002/adma.202309416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 10/11/2023] [Indexed: 10/21/2023]
Abstract
A multichannel/multicolor visible light communication (VLC) system using entirely organic components, including organic light emitting diodes (OLEDs) and organic photodiodes (OPDs), is developed to demonstrate indoor lighting applications where the integration of OLEDs and OPDs has significant potential. To achieve this, tricolor (Red/Green/Blue(R/G/B))-selective OPD arrays for the receiver and tricolor OLED arrays for the emitter are developed. For (R/G/B)-selective OPDs, a Fabry-Pérot electrode to enhance color selectivity and a thick junction structure to effectively accommodate a wide range of driving voltages are introduced. For tricolor OLEDs, fluorescent-emitting materials are used to enhance the operating frequency in addition to introducing a cavity structure to achieve narrow emission. Utilizing these spectrally refined tricolor OPDs/OLEDs, a VLC system is designed for indoor lighting applications, and a systematic analysis of their signal-to-interference ratio dependence on the distance or angle between the transmitter and receiver is performed. The study's findings indicate the importance of emission angle-dependent wavelength shift of the OLED and the luminosity function, which varies with wavelength, in the R/G/B mixed-white-light-based VLC systems. Finally, the feasibility of VLC using tricolor OPDs/OLEDs in the real-life context of indoor white-color lighting is demonstrated, showing that the transmitted data patterns well-matched the received data patterns.
Collapse
Affiliation(s)
- Dowan Kim
- Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Hyung-Jun Park
- Department of Intelligence Semiconductor Engineering, Ajou University, Suwon, 16499, Republic of Korea
| | - Seo-Hee Jung
- Department of Materials Science and Engineering, Inha University, Incheon, 22212, Republic of Korea
| | - Won Jun Pyo
- Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Syed Zahid Hassan
- Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Hye Ryun Sim
- Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Jeong-Hwan Lee
- Department of Materials Science and Engineering, Inha University, Incheon, 22212, Republic of Korea
- 3D Convergence Center, Inha University, Incheon, 22212, Republic of Korea
| | - Dong-Woo Jee
- Department of Intelligence Semiconductor Engineering, Ajou University, Suwon, 16499, Republic of Korea
- Department of Electrical and Computer Engineering, Ajou University, Suwon, 16499, Republic of Korea
| | - Dae Sung Chung
- Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| |
Collapse
|
4
|
Yoshida K, Gong J, Kanibolotsky AL, Skabara PJ, Turnbull GA, Samuel IDW. Electrically driven organic laser using integrated OLED pumping. Nature 2023; 621:746-752. [PMID: 37758890 PMCID: PMC10533406 DOI: 10.1038/s41586-023-06488-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 07/27/2023] [Indexed: 09/29/2023]
Abstract
Organic semiconductors are carbon-based materials that combine optoelectronic properties with simple fabrication and the scope for tuning by changing their chemical structure1-3. They have been successfully used to make organic light-emitting diodes2,4,5 (OLEDs, now widely found in mobile phone displays and televisions), solar cells1, transistors6 and sensors7. However, making electrically driven organic semiconductor lasers is very challenging8,9. It is difficult because organic semiconductors typically support only low current densities, suffer substantial absorption from injected charges and triplets, and have additional losses due to contacts10,11. In short, injecting charges into the gain medium leads to intolerable losses. Here we take an alternative approach in which charge injection and lasing are spatially separated, thereby greatly reducing losses. We achieve this by developing an integrated device structure that efficiently couples an OLED, with exceptionally high internal-light generation, with a polymer distributed feedback laser. Under the electrical driving of the integrated structure, we observe a threshold in light output versus drive current, with a narrow emission spectrum and the formation of a beam above the threshold. These observations confirm lasing. Our results provide an organic electronic device that has not been previously demonstrated, and show that indirect electrical pumping by an OLED is a very effective way of realizing an electrically driven organic semiconductor laser. This provides an approach to visible lasers that could see applications in spectroscopy, metrology and sensing.
Collapse
Affiliation(s)
- Kou Yoshida
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK
| | - Junyi Gong
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK
| | - Alexander L Kanibolotsky
- WestCHEM, School of Chemistry, University of Glasgow, Glasgow, UK
- Institute of Physical-Organic Chemistry and Coal Chemistry, Kyiv, Ukraine
| | - Peter J Skabara
- WestCHEM, School of Chemistry, University of Glasgow, Glasgow, UK
| | - Graham A Turnbull
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK.
| | - Ifor D W Samuel
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, UK.
| |
Collapse
|
5
|
Sawatzki-Park M, Wang SJ, Kleemann H, Leo K. Highly Ordered Small Molecule Organic Semiconductor Thin-Films Enabling Complex, High-Performance Multi-Junction Devices. Chem Rev 2023. [PMID: 37315945 DOI: 10.1021/acs.chemrev.2c00844] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Organic semiconductors have opened up many new electronic applications, enabled by properties like flexibility, low-cost manufacturing, and biocompatibility, as well as improved ecological sustainability due to low energy use during manufacturing. Most current devices are made of highly disordered thin-films, leading to poor transport properties and, ultimately, reduced device performance as well. Here, we discuss techniques to prepare highly ordered thin-films of organic semiconductors to realize fast and highly efficient devices as well as novel device types. We discuss the various methods that can be implemented to achieve such highly ordered layers compatible with standard semiconductor manufacturing processes and suitable for complex devices. A special focus is put on approaches utilizing thermal treatment of amorphous layers of small molecules to create crystalline thin-films. This technique has first been demonstrated for rubrene─an organic semiconductor with excellent transport properties─and extended to some other molecular structures. We discuss recent experiments that show that these highly ordered layers show excellent lateral and vertical mobilities and can be electrically doped to achieve high n- and p-type conductivities. With these achievements, it is possible to integrate these highly ordered layers into specialized devices, such as high-frequency diodes or completely new device principles for organics, e.g., bipolar transistors.
Collapse
Affiliation(s)
- Michael Sawatzki-Park
- Dresden Integrated Center for Applied Photophysics and Photonic Materials (IAPP), Technische Universität Dresden, Dresden 01219, Germany
| | - Shu-Jen Wang
- Dresden Integrated Center for Applied Photophysics and Photonic Materials (IAPP), Technische Universität Dresden, Dresden 01219, Germany
| | - Hans Kleemann
- Dresden Integrated Center for Applied Photophysics and Photonic Materials (IAPP), Technische Universität Dresden, Dresden 01219, Germany
| | - Karl Leo
- Dresden Integrated Center for Applied Photophysics and Photonic Materials (IAPP), Technische Universität Dresden, Dresden 01219, Germany
| |
Collapse
|
6
|
Gao S, Cui Z, Li F. Doublet-emissive materials for organic light-emitting diodes: exciton formation and emission processes. Chem Soc Rev 2023; 52:2875-2885. [PMID: 37052349 DOI: 10.1039/d2cs00772j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Abstract
Doublet-emission is mainly discovered in stable radicals, lanthanide-metal complexes with an f1 electron configuration and transition-metal complexes with a low-spin d5 electron configuration, and has a distinct radiation mechanism from closed-shell luminescent molecules and thus technology opportunities. There exists an unpaired electron in the frontier molecular orbitals which enables efficient nanosecond-scale luminescence in these materials due to the spin-allowed transitions between doublet-spin states. In this review, we summarize recent advances in these materials and their application in organic light emitting diodes (OLEDs). The photoluminescence and electroluminescence mechanisms of different doublet-emissive molecular systems are discussed, in addition to the photophysical phenomena arising from doublet states. We also outline the current challenges faced by each molecular system, and the potential outlook on the future research trends in this field.
Collapse
Affiliation(s)
- Shengxiang Gao
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China.
| | - Zhiyuan Cui
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China.
| | - Feng Li
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, P. R. China.
| |
Collapse
|
7
|
He C, Lim Y, Murata H. Study of using different colors of fluorescent fibers as optical antennas in white LED based-visible light communications. OPTICS EXPRESS 2023; 31:4015-4028. [PMID: 36785379 DOI: 10.1364/oe.481017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 01/07/2023] [Indexed: 06/18/2023]
Abstract
A fluorescent fiber can be used as an optical antenna in visible light communication (VLC) for simultaneous optical filtering and light concentration and therefore to build a compact receiver. Since its light concentration principle is based on fluorescence, it can exceed the étendue limit and achieve both a high concentration gain and a wide field-of-view (FOV). In addition, because the photoluminescence (PL) lifetime of the fluorophore is typically only several nanoseconds, it can support high-speed data transmissions. When a fluorescent fiber antenna is used in a white light-emitting diode (LED)-based VLC system, the transmission performance highly depends on how the absorption and emission spectra of the fluorophore are associated with both the spectrum of the LED and the responsivity of the silicon photodetector. In this paper, we analyze the performance of several different commercially available fluorescent fibers. We show that, when the data rate is low or the transmission distance is long, since the light emitted from a red fluorescent fiber is associated with high silicon responsivities, it can result in high signal-to-noise ratios (SNRs) at the receiver output and therefore lead to low transmission error rates. In contrast, when the data rate is high or the transmission distance is relatively short, the bandwidth dominates the overall performance and consequently the green fluorescent fiber has better performance since it only absorbs the light emitted from the blue LED rather than the light emitted from the yellow phosphor.
Collapse
|
8
|
Pradhan S, Dalmases M, Taghipour N, Kundu B, Konstantatos G. Colloidal Quantum Dot Light Emitting Diodes at Telecom Wavelength with 18% Quantum Efficiency and Over 1 MHz Bandwidth. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2200637. [PMID: 35508607 PMCID: PMC9284174 DOI: 10.1002/advs.202200637] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 04/05/2022] [Indexed: 05/19/2023]
Abstract
Developing high performance, low-cost solid-state light emitters in the telecom wavelength bandwidth is of paramount importance for infrared light-based communications. Colloidal quantum dot (CQD) based light emitting diodes (LEDs) have shown tremendous advances in recent times through improvement in synthesis chemistry, surface property, and device structures. Despite the tremendous advancements of CQD based LEDs in the visible range with efficiency reaching theoretical limits, their short-wave infrared (SWIR) counterparts mainly based on lead chalcogenide CQDs, have shown lower performance (≈8%). Here the authors report on highly efficient SWIR CQD LEDs with a recorded EQE of 11.8% enabled by the use of a binary CQD matrix comprising QD populations of different bandgaps at the emission wavelength of 1550 nm. By further optimizing the optical out-coupling via the use of a hemispherical lens to reduce optical waveguide loss, the EQE of the LED increased to 18.6%. The CQD LED has an electrical bandwidth of 2 MHz, which motivated them to demonstrate its use in the first SWIR free-space optical transmission link based entirely on CQD technology (photodetector and light emitter) opening a new window of applications for CQD optoelectronics.
Collapse
Affiliation(s)
- Santanu Pradhan
- ICFO‐Institut de Ciències FotòniquesThe Barcelona Institute of Science and TechnologyCastelldefelsBarcelona08860Spain
- Present address:
Centre of NanotechnologyIndian Institute of Technology RoorkeeRoorkee247667India
| | - Mariona Dalmases
- ICFO‐Institut de Ciències FotòniquesThe Barcelona Institute of Science and TechnologyCastelldefelsBarcelona08860Spain
| | - Nima Taghipour
- ICFO‐Institut de Ciències FotòniquesThe Barcelona Institute of Science and TechnologyCastelldefelsBarcelona08860Spain
| | - Biswajit Kundu
- ICFO‐Institut de Ciències FotòniquesThe Barcelona Institute of Science and TechnologyCastelldefelsBarcelona08860Spain
| | - Gerasimos Konstantatos
- ICFO‐Institut de Ciències FotòniquesThe Barcelona Institute of Science and TechnologyCastelldefelsBarcelona08860Spain
- ICREA—Institució Catalana de Recerca i Estudis AvançatsPasseig Lluís Companys 23Barcelona08010Spain
| |
Collapse
|
9
|
Xiong J, Hsiang EL, He Z, Zhan T, Wu ST. Augmented reality and virtual reality displays: emerging technologies and future perspectives. LIGHT, SCIENCE & APPLICATIONS 2021; 10:216. [PMID: 34697292 PMCID: PMC8546092 DOI: 10.1038/s41377-021-00658-8] [Citation(s) in RCA: 137] [Impact Index Per Article: 45.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Revised: 09/26/2021] [Accepted: 10/04/2021] [Indexed: 05/19/2023]
Abstract
With rapid advances in high-speed communication and computation, augmented reality (AR) and virtual reality (VR) are emerging as next-generation display platforms for deeper human-digital interactions. Nonetheless, to simultaneously match the exceptional performance of human vision and keep the near-eye display module compact and lightweight imposes unprecedented challenges on optical engineering. Fortunately, recent progress in holographic optical elements (HOEs) and lithography-enabled devices provide innovative ways to tackle these obstacles in AR and VR that are otherwise difficult with traditional optics. In this review, we begin with introducing the basic structures of AR and VR headsets, and then describing the operation principles of various HOEs and lithography-enabled devices. Their properties are analyzed in detail, including strong selectivity on wavelength and incident angle, and multiplexing ability of volume HOEs, polarization dependency and active switching of liquid crystal HOEs, device fabrication, and properties of micro-LEDs (light-emitting diodes), and large design freedoms of metasurfaces. Afterwards, we discuss how these devices help enhance the AR and VR performance, with detailed description and analysis of some state-of-the-art architectures. Finally, we cast a perspective on potential developments and research directions of these photonic devices for future AR and VR displays.
Collapse
Affiliation(s)
- Jianghao Xiong
- College of Optics and Photonics, University of Central Florida, Orlando, FL, 32816, USA
| | - En-Lin Hsiang
- College of Optics and Photonics, University of Central Florida, Orlando, FL, 32816, USA
| | - Ziqian He
- College of Optics and Photonics, University of Central Florida, Orlando, FL, 32816, USA
| | - Tao Zhan
- College of Optics and Photonics, University of Central Florida, Orlando, FL, 32816, USA
| | - Shin-Tson Wu
- College of Optics and Photonics, University of Central Florida, Orlando, FL, 32816, USA.
| |
Collapse
|
10
|
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: 38] [Impact Index Per Article: 12.7] [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.
Collapse
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
| |
Collapse
|
11
|
Organic Diode Laser Dynamics: Rate-Equation Model, Reabsorption, Validation and Threshold Predictions. PHOTONICS 2021. [DOI: 10.3390/photonics8070279] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We present and analyze a simple model based on six rate equations for an electrically pumped organic diode laser. The model applies to organic host-guest systems and includes Stoke-shifted reabsorption in a self-consistent manner. With the validated model for the Alq3:DCM host-guest system, we predict the threshold for short-pulse laser operation. We predict laser operation characterized by damped relaxation oscillations in the GHz regime and several orders of magnitude linewidth narrowing. Prospect for CW steady-state laser operation is discussed.
Collapse
|
12
|
Cai Y, Haggar JIH, Zhu C, Feng P, Bai J, Wang T. Direct Epitaxial Approach to Achieve a Monolithic On-Chip Integration of a HEMT and a Single Micro-LED with a High-Modulation Bandwidth. ACS APPLIED ELECTRONIC MATERIALS 2021; 3:445-450. [PMID: 33615233 PMCID: PMC7885730 DOI: 10.1021/acsaelm.0c00985] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 01/04/2021] [Indexed: 06/02/2023]
Abstract
Visible light communications (VLC) require III-nitride visible micro-light-emitting diodes (μLEDs) with a high-modulation bandwidth. Such μLEDs need to be driven at a high injection current density on a kA/cm2 scale, which is about 2 orders of magnitude higher than those for normal visible LED operation. μLEDs are traditionally fabricated by dry-etching techniques where dry-etching-induced damages are unavoidable, leading to both a substantial reduction in performance and a great challenge to viability at a high injection current density. Furthermore, conventional biasing (which is simply applied across a p-n junction) is good enough for normal LED operation but generates a great challenge for a single μLED, which needs to be modulated at a high injection current density and at a high frequency. In this work, we have proposed a concept for an epitaxial integration and then demonstrated a completely different method that allows us to achieve an epitaxial integration of a single μLED with a diameter of 20 μm and an AlGaN/GaN high-electron-mobility transistor (HEMT), where the emission from a single μLED is modulated by tuning the gate voltage of its HEMT. Furthermore, such a direct epitaxial approach has entirely eliminated any dry-etching-induced damages. As a result, we have demonstrated an epitaxial integration of monolithic on-chip μLED-HEMT with a record modulation bandwidth of 1.2 GHz on industry-compatible c-plane substrates.
Collapse
|
13
|
Abstract
Smart materials displaying changes in color and optical properties in response
to acid stimuli are known as acidochromic materials. The recent progress and emerging
trends in the field of smart organic materials with acidochromic properties, reported in the
last seven years, are presented herein. The molecular design of acidochromic organic materials,
the origin of the chromic and fluorochromic response to acid stimuli, and related
mechanisms are also discussed. Materials and systems covered in the review are divided
according to the presence of basic moiety undergoing reversible protonation/
deprotonation, such as pyridine, quinoline, quinoxaline, azole, amine derivatives, etc.,
in the molecules. Many donor-acceptor molecules displaying acidochromic behavior are
cited. Alterations in visual color change and optical properties supporting acidochromism
are discussed for each example. Mechanistic studies based on the theoretical calculations,
single crystal X-ray diffraction analysis, and powder pattern diffraction analysis are also discussed here. The
application of these acidochromic molecules as acid-base switches, sensor films, self-erasable and rewritable
media, data security inks, data encryption, molecular logic gates, etc., are also reported. Thus, this review article
aims at giving an insight into the design, characterization, mechanism, and applications of organic acidochromic
materials, which will guide the researchers in designing and fine-tuning new acidochromic materials
for desired applications.
Collapse
Affiliation(s)
- Tanisha Sachdeva
- Department of Chemistry, University of Delhi, Delhi 110 007, India
| | - Shalu Gupta
- Department of Chemistry, University of Delhi, Delhi 110 007, India
| | | |
Collapse
|
14
|
Wei Z, Zhang L, Wang L, Chen CJ, Wang Z, Chen KC, Wu MC, Dong Y, Wang L, Luo Y, Fu HY. Multi-user high-speed QAM-OFDMA visible light communication system using a 75-µm single layer quantum dot micro-LED. OPTICS EXPRESS 2020; 28:18332-18342. [PMID: 32680031 DOI: 10.1364/oe.395419] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 05/28/2020] [Indexed: 06/11/2023]
Abstract
Next-generation visible light communication (VLC) is envisioned to evolve into a high-speed and multi-user system. In this work, a 75-µm single layer quantum dot (QD) micro-LED was fabricated, packaged and used to experimentally demonstrate a 3-meter QAM-OFDMA VLC system affording multiple users with a 1.06-GHz modulation bandwidth. The OFDMA system realized data rates of 1.2 Gbps and 750 Mbps with a BER of 0 and 3.6×10-3 for two independent users with a 1:1 bandwidth ratio, respectively. Additional sub-carrier allocation strategies and scenarios of 2∼6 users have been further evaluated, and all proposed strategies reach the sum-rate of beyond 1.41 Gbps while satisfying the forward error correction (FEC) criteria.
Collapse
|
15
|
Manousiadis PP, Yoshida K, Turnbull GA, Samuel IDW. Organic semiconductors for visible light communications. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2020; 378:20190186. [PMID: 32114909 PMCID: PMC7061996 DOI: 10.1098/rsta.2019.0186] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 01/20/2020] [Indexed: 05/28/2023]
Abstract
Organic semiconductors are an important class of optoelectronic material that are widely studied because of the scope for tuning their properties by tuning their chemical structure, and simple fabrication to make flexible films and devices. Although most effort has focused on developing displays and lighting from these materials, their distinctive properties also make them of interest for visible light communications (VLCs). This article explains how their properties make them suitable for VLC and reviews the main uses that have been explored. On the transmitter side, record white VLC communication has been achieved by using organic semiconductors as colour converters, while direct modulation of organic light-emitting diodes is also possible and could be of interest for display-to-display communication. On the receiver side, organic solar cells can be used to harvest power and data simultaneously, and fluorescent antennas enable fast and sensitive receivers with large field of view. This article is part of the theme issue 'Optical wireless communication'.
Collapse
Affiliation(s)
| | | | - Graham A. Turnbull
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
| | - Ifor D. W. Samuel
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
| |
Collapse
|
16
|
Haas H, Elmirghani J, White I. Optical wireless communication. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2020; 378:20200051. [PMID: 32114912 PMCID: PMC7062008 DOI: 10.1098/rsta.2020.0051] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Optical wireless communication has attracted significant interest recently in industry and academia. This special issue features a collection of inter-related papers with the intention to cover all necessary multidisciplinary challenges to realize optical wireless networks. We hope that this special issue will serve as a comprehensive reference and that it will be a resource which fosters many more new ideas for this rapidly emerging field. This article is part of the theme issue 'Optical wireless communication'.
Collapse
Affiliation(s)
- Harald Haas
- School of Engineering, LiFi Research and Development Centre, Institute for Digital Communications, University of Edinburgh, Edinburgh EH9 3JL, UK
- e-mail:
| | - Jaafar Elmirghani
- School of Electronic and Electrical Engineering, Institute of Communication and Power Networks, University of Leeds, Leeds LS2 9JT, UK
| | - Ian White
- Vice-Chancellor's Office, University of Bath, Claverton Down, Bath BA2 7AY, UK
| |
Collapse
|