1
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Riley DB, Meredith P, Armin A. Exciton diffusion in organic semiconductors: precision and pitfalls. NANOSCALE 2024. [PMID: 39171513 DOI: 10.1039/d4nr02467b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/23/2024]
Abstract
Nanometer exciton diffusion is a fundamental process important in virtually all applications of organic semiconductors. Many measurement techniques have been developed to measure exciton diffusion length (LD) at the nanometer scale; however, these techniques have common challenges that the community has worked for decades to overcome. In this perspective, we lay out the principal challenges researchers need to overcome to obtain an accurate measurement of LD. We then examine the most common techniques used to measure LD with respect to these challenges and describe solutions developed to overcome them. This analysis leads to the suggestion that static quenching techniques underestimate LD due to uncertainties in the quenching behavior, while time-resolved exciton-exciton annihilation (EEA) techniques overestimate LD based on experimental conditions, we advance steady-state EEA techniques as an alternative that overcome many of the challenges of these other techniques while preserving accuracy. We support this hypothesis with a meta-analysis of LD measured across various organic semiconductors and measurement techniques. We intend this investigation to provide a framework for researchers to interpret and compare findings across measurement techniques and to guide researchers on how to obtain the most accurate results for each technique in question.
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Affiliation(s)
- Drew B Riley
- Sustainable Advanced Materials (Sêr-SAM), Centre for Integrative Semiconductor Materials (CISM), Department of Physics, Swansea University Bay Campus, Swansea SA1 8EN, UK.
| | - Paul Meredith
- Sustainable Advanced Materials (Sêr-SAM), Centre for Integrative Semiconductor Materials (CISM), Department of Physics, Swansea University Bay Campus, Swansea SA1 8EN, UK.
| | - Ardalan Armin
- Sustainable Advanced Materials (Sêr-SAM), Centre for Integrative Semiconductor Materials (CISM), Department of Physics, Swansea University Bay Campus, Swansea SA1 8EN, UK.
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2
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Lin H, Xiao Z, Chen C, Cai Z, Liang Y, Zhang W. Charge photogeneration and recombination dynamics in non-fullerene solar cells based on a polymer donor with a mono-fluorinated π-bridge. Phys Chem Chem Phys 2024; 26:21476-21484. [PMID: 39081022 DOI: 10.1039/d4cp02014f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/15/2024]
Abstract
Non-symmetric fluorine substitution is an important route for designing π-conjugated polymers for high-performance solar cells. However, excited state dynamics in a non-symmetric fluorinated polymer and solar cells are poorly understood. In this work, excited state dynamics in a neat mono-fluorinated polymer (PTzBI-dF) film and blend films (PTzBI-dF:Y6) were studied using time-resolved spectroscopy. For the neat donor film, we found the activation energy of the PTzBI-dF film transiting from radiative states to non-radiative states to be ∼58 meV. Besides, we found that both exciton diffusion coefficient and exciton diffusion length in the PTzBI-dF film are higher than those in the PTzBI-Cl film, which has no fluorinated π-bridge. The high exciton diffusion length of the PTzBI-dF film benefits from its long exciton lifetime (∼327.8 ps), which is much longer than that of the polymer donors such as P3HT and PM6. For PTzBI-dF:Y6 blend films, we found that the energy level offsets of the HOMO (0.13 eV) and LUMO (0.23 eV) are sufficient to dissociate the acceptor and donor excitons, respectively. Besides, we found that carrier recombination in PTzBI-dF:Y6 and PTzBI-Cl:Y6 blend films are dominated by bimolecular recombination processes, and thermal annealing treatment has a weak influence on the charge photogeneration and recombination process of the PTzBI-dF:Y6 film at an ultrafast time scale. Thus, this work is helpful for understanding photoelectrical conversion processes in non-symmetric fluorinated polymer-based solar cells.
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Affiliation(s)
- Haobo Lin
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China.
- Research Center for Advanced Information Materials (CAIM), Huangpu Research and Graduate School of Guangzhou University, Guangzhou 510006, China
| | - Zijie Xiao
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China.
| | - Chuan Chen
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China.
| | - Zekai Cai
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China.
| | - Yuan Liang
- School of Electronics and Communication Engineering, Guangzhou University, Guangzhou, 510006, China.
| | - Wei Zhang
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China.
- Research Center for Advanced Information Materials (CAIM), Huangpu Research and Graduate School of Guangzhou University, Guangzhou 510006, China
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3
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Cai Z, Hu R, Xiao Z, Feng J, Zou X, Wen G, Dong G, Zhang W. Charge photogeneration dynamics in non-fullerene polymer solar cells with fluorinated and non-fluorinated acceptors. J Chem Phys 2024; 160:074702. [PMID: 38364001 DOI: 10.1063/5.0177876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 01/22/2024] [Indexed: 02/18/2024] Open
Abstract
In this work, charge photogeneration and recombination processes of PM6:IDIC-4F and PM6:IDIC blend films were investigated by the steady-state and time-resolved spectroscopies, as well as the time-dependent density functional theory calculations. The peaks in absorption and photoluminescence (PL) spectra of IDIC and IDIC-4F solutions were assigned by combining the experiment and the simulation of UV-vis absorption and PL spectra. For neat acceptor films, the exciton diffusion length of neat IDIC and IDIC-4F films was estimated as ∼28.9 and ∼19.9 nm, respectively. For PM6-based blend films, we find that the fluorine substitution engineering on the IDIC acceptor material can increase the phase separate size of acceptor material in blend films, resulting in the reduction of dissociation efficiencies of acceptor excitons. In addition, we find that the charge recombination in PM6:IDIC-4F is dominated by bimolecular recombination, in comparison to geminate type carrier recombination in PM6:IDIC blend films. In addition, we find that thermal annealing treatment has a weak influence on carrier recombination but slightly reduces the exciton dissociation efficiency of acceptor in PM6:IDIC blend films, leading to a slightly reduced power conversion efficiency of PM6:IDIC solar cells. These results may shed light on the design of high-performance semiconductor molecules for application in solar cells.
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Affiliation(s)
- Zekai Cai
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China
| | - Rong Hu
- School of Materials Science and Engineering, Chongqing University of Arts and Sciences, Chongqing 402160, China
| | - Zijie Xiao
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China
| | - Junyi Feng
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China
| | - Xianshao Zou
- Qingdao Innovation and Development Base, Harbin Engineering University, Qingdao CN-266 000, China
- Division of Chemical Physics, Lund University, 221 00 Lund, Sweden
| | - Guanzhao Wen
- Research Center for Advanced Information Materials (CAIM), Huangpu Research and Graduate School of Guangzhou University, Guangzhou 510006, China
| | - Geng Dong
- Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou 515041, China
| | - Wei Zhang
- School of Physics and Materials Science, Guangzhou University, Guangzhou 510006, China
- Research Center for Advanced Information Materials (CAIM), Huangpu Research and Graduate School of Guangzhou University, Guangzhou 510006, China
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4
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Reiker T, Liu Z, Winter C, Cappellari MV, Abradelo DG, Strassert CA, Zhang D, Zacharias H. Ultrafast electron dynamics in excited states of conjugated thiophene-fluorene organic polymer (pF8T2) thin films. Phys Chem Chem Phys 2024; 26:4736-4751. [PMID: 38251969 DOI: 10.1039/d3cp00502j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2024]
Abstract
The electronic states of poly(9,9-dioctylfluorenyl-alt-bithiophene) pF8T2 on H/Si(100) substrates, prototypical for organic photovoltaics, were investigated by ultrafast photoelectron spectroscopy and by time-resolved fluorescence studies. Occupied and unoccupied electronic states were analysed by ultraviolet photoelectron spectroscopy (UPS), static and dynamic femtosecond two-photon photoemission (2PPE), and time-correlated single photon counting (TCSPC). Time-resolved measurements allow assessment of population lifetimes of intermediate states. The combination of time-resolved photoelectron spectroscopy and fluorescence excitation allows following the electronic dynamics in excited states from the femtosecond to the nanosecond time scale. For this prototypical material the electron kinetic energy resolved lifetimes range from about a few tens of femtoseconds up to hundreds of picoseconds. After annealing these types of organic thin films the efficiency of organic solar cells usually increases. We show that annealing does not influence the initial ultrafast charge generation processes, but the long-lived states. However, the nanosecond scale fluorescence lifetimes measured by TCSPC are prolonged after annealing, which therefore is identified as the cause of a greater exciton diffusion range and thus is beneficial for charge carrier extraction.
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Affiliation(s)
- T Reiker
- Center for Soft Nanoscience, University of Münster, 48149 Münster, Germany.
- Physics Institute, University of Münster, 48149 Münster, Germany
| | - Z Liu
- Organic Solids Laboratory, Institute of Chemistry, Chinese Academy of Science, Beijing 100190, P. R. China
| | - C Winter
- Physics Institute, University of Münster, 48149 Münster, Germany
| | - M V Cappellari
- Center for Nanotechnology and Institute for Inorganic and Analytical Chemistry, University of Münster, Heisenbergstraße 11, 48149 Münster, Germany
| | - D Gonzalez Abradelo
- Center for Nanotechnology and Institute for Inorganic and Analytical Chemistry, University of Münster, Heisenbergstraße 11, 48149 Münster, Germany
| | - C A Strassert
- Center for Nanotechnology and Institute for Inorganic and Analytical Chemistry, University of Münster, Heisenbergstraße 11, 48149 Münster, Germany
| | - D Zhang
- Organic Solids Laboratory, Institute of Chemistry, Chinese Academy of Science, Beijing 100190, P. R. China
| | - H Zacharias
- Center for Soft Nanoscience, University of Münster, 48149 Münster, Germany.
- Physics Institute, University of Münster, 48149 Münster, Germany
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5
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Zhao N, Zhang R, Zou X, Su X, Dang F, Wen G, Zhang W, Zheng K, Chen H, Wu K. Photoinduced Polaron Formation in a Polymerized Electron-Acceptor Semiconductor. J Phys Chem Lett 2022; 13:5143-5150. [PMID: 35658092 DOI: 10.1021/acs.jpclett.2c01015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Polymerized small molecular acceptor (PSMA) based all-polymer solar cells (all-PSC) have achieved power conversion efficiencies (PCE) over 16%, and the PSMA is considered to hold great promise for further improving the performance of all-PSC. Yet, in comparison with that of the polymer donor, the photophysics of a polymerized acceptor remains poorly understood. Herein, the excited state dynamics in a polymerized acceptor PZT810 was comprehensively investigated under various pump intensities and photon energies. The excess excitation energy was found to play a key role in excitons dissociation into free polarons for neat PSMA films, while free polarons cannot be generated from the polaron pairs in neat acceptor films. This work reveals an in-depth understanding of relaxation dynamics for PSMAs and that the underlying photophysical origin of PSMA can be mediated by excitation energies and intensities. These results would benefit the realization of the working mechanism for all-PSC and the designing of new PSMAs.
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Affiliation(s)
- Ningjiu Zhao
- Songshan Lake Materials Laboratory, Dongguan, 523808, China
| | - Rui Zhang
- Department of Physics, Chemsitry and Biology (IFM), Linköping University, Linköping, SE-58183, Sweden
| | - Xianshao Zou
- Division of Chemical Physics, Lund University, Lund, 22100, Sweden
| | - Xiaojun Su
- Department of Basic Courses, Guangzhou Maritime University, Guangzhou, 510725, China
| | - Fan Dang
- Songshan Lake Materials Laboratory, Dongguan, 523808, China
| | - Guanzhao Wen
- School of Physics and Materials Science, Guangzhou University, Guangzhou, 510006, China
| | - Wei Zhang
- School of Physics and Materials Science, Guangzhou University, Guangzhou, 510006, China
- Research Center for Advanced Information Materials (CAIM), Huangpu Research and Graduate School of Guangzhou University, Guangzhou, 510006, China
- Guangzhou University-Linköping University Research Center on Urban Sustainable Development, Guangzhou University, Guangzhou, 510006, China
| | - Kaibo Zheng
- Division of Chemical Physics, Lund University, Lund, 22100, Sweden
| | - Hailong Chen
- Songshan Lake Materials Laboratory, Dongguan, 523808, China
| | - Kehui Wu
- Songshan Lake Materials Laboratory, Dongguan, 523808, China
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6
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Shibu A, Middleton C, Kwiatkowski CO, Kaushal M, Gillen JH, Walter MG. Self-Assembly-Directed Exciton Diffusion in Solution-Processable Metalloporphyrin Thin Films. Molecules 2021; 27:35. [PMID: 35011266 PMCID: PMC8746414 DOI: 10.3390/molecules27010035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 12/14/2021] [Accepted: 12/15/2021] [Indexed: 11/21/2022] Open
Abstract
The study of excited-state energy diffusion has had an important impact in the development and optimization of organic electronics. For instance, optimizing excited-state energy migration in the photoactive layer in an organic solar cell device has been shown to yield efficient solar energy conversion. Despite the crucial role that energy migration plays in molecular electronic device physics, there is still a great deal to be explored to establish how molecular orientation impacts energy diffusion mechanisms. In this work, we have synthesized a new library of solution-processable, Zn (alkoxycarbonyl)phenylporphyrins containing butyl (ZnTCB4PP), hexyl (ZnTCH4PP), 2-ethylhexyl (ZnTCEH4PP), and octyl (ZnTCO4PP) alkoxycarbonyl groups. We establish that, by varying the length of the peripheral alkyl chains on the metalloporphyrin macrocycle, preferential orientation and molecular self-assembly is observed in solution-processed thin films. The resultant arrangement of molecules consequently affects the electronic and photophysical characteristics of the metalloporphyrin thin films. The various molecular arrangements in the porphyrin thin films and their resultant impact were determined using UV-Vis absorption spectroscopy, steady-state and time-resolved fluorescence emission lifetimes, and X-ray diffraction in thin films. The films were doped with C60 quencher molecules and the change in fluorescence was measured to derive a relative quenching efficiency. Using emission decay, relative quenching efficiency, and dopant volume fraction as input, insights on exciton diffusion coefficient and exciton diffusion lengths were obtained from a Monte Carlo simulation. The octyl derivative (ZnTCO4PP) showed the strongest relative fluorescence quenching and, therefore, the highest exciton diffusion coefficient (5.29 × 10-3 cm2 s-1) and longest exciton diffusion length (~81 nm). The octyl derivative also showed the strongest out-of-plane stacking among the metalloporphyrins studied. This work demonstrates how molecular self-assembly can be used to modulate and direct exciton diffusion in solution-processable metalloporphyrin thin films engineered for optoelectronic and photonic applications.
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Affiliation(s)
| | | | | | | | | | - Michael G. Walter
- Department of Chemistry, University of North Carolina at Charlotte, Charlotte, NC 28223-0001, USA; (A.S.); (C.M.); (C.O.K.); (M.K.); (J.H.G.)
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7
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Wen G, Zou X, Hu R, Peng J, Chen Z, He X, Dong G, Zhang W. Ground- and excited-state characteristics in photovoltaic polymer N2200. RSC Adv 2021; 11:20191-20199. [PMID: 35479889 PMCID: PMC9033976 DOI: 10.1039/d1ra01474a] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 05/31/2021] [Indexed: 02/05/2023] Open
Abstract
As a classical polymer acceptor material, N2200 has received extensive attention and research in the field of polymer solar cells (PSCs). However, the intrinsic properties of ground- and excited-states in N2200, which are critical for the application of N2200 in PSCs, remain poorly understood. In this work, the ground- and excited-state properties of N2200 solution and film were studied by steady-state and time-resolved spectroscopies as well as time-dependent density functional theory (TD-DFT) calculations. The transition mechanism of absorption peaks of N2200 was evaluated through the natural transition orbitals (NTOs) and hole-electron population analysis by TD-DFT. Time-resolved photoluminescence (TRPL) study shows that the lifetimes of singlet excitons in N2200 chlorobenzene solution and film are ∼90 ps and ∼60 ps, respectively. Considering the absolute quantum yield of N2200 film, we deduce that the intrinsic lifetime of singlet exciton can be as long as ∼20 ns. By comparing the TRPL and transient absorption (TA) kinetics, we find that the decay of singlet excitons in N2200 solution is dominated by a fast non-radiative decay process, and the component induced by intersystem crossing is less than 5%. Besides that, the annihilation radius, annihilation rate and diffusion length of singlet excitons in N2200 film were evaluated as 3.6 nm, 2.5 × 10-9 cm3 s-1 and 4.5 nm, respectively. Our work provides comprehensive information on the excited states of N2200, which is helpful for the application of N2200 in all-PSCs.
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Affiliation(s)
- Guanzhao Wen
- School of Physics and Materials Science, Guangzhou University Guangzhou 510006 China +86-136-4279-2676
| | - Xianshao Zou
- Division of Chemical Physics, Lund University Lund 22100 Sweden
| | - Rong Hu
- School of Materials Science and Engineering, Chongqing University of Arts and Sciences Chongqing 402160 China
| | - Jun Peng
- School of Physics and Materials Science, Guangzhou University Guangzhou 510006 China +86-136-4279-2676
| | - Zhifeng Chen
- School of Physics and Materials Science, Guangzhou University Guangzhou 510006 China +86-136-4279-2676
| | - Xiaochuan He
- Songshan Lake Materials Laboratory Dongguan 523808 China
| | - Geng Dong
- Department of Biochemistry and Molecular Biology, Shantou University Medical College Shantou 515041 China +86-187-3110-6711
- Medical Informatics Research Center, Shantou University Medical College Shantou 515041 China
| | - Wei Zhang
- School of Physics and Materials Science, Guangzhou University Guangzhou 510006 China +86-136-4279-2676
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8
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Mechanistic insights on improved performance of PCDTBT:PC71BM hetero-structured organic photovoltaic cells via interfacing CdSe/ZnS nanostructures. APPLIED NANOSCIENCE 2021. [DOI: 10.1007/s13204-021-01789-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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9
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Qiu D, Adil MA, Lu K, Wei Z. The Crystallinity Control of Polymer Donor Materials for High-Performance Organic Solar Cells. Front Chem 2020; 8:603134. [PMID: 33330397 PMCID: PMC7732501 DOI: 10.3389/fchem.2020.603134] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2020] [Accepted: 10/12/2020] [Indexed: 11/13/2022] Open
Abstract
Bulk heterojunction (BHJ) organic solar cells (OSCs) can be regarded as one of the most promising energy generation technologies for large-scale applications. Despite their several well-known drawbacks, the devices where polymers are employed as the donor are still leading the OSC universe in terms of performance. Such performance generally depends upon various critical factors such as the crystallinity of the material, the crystallization process during the film formation, and also the final film morphology. Despite a few reviews on the structure of the polymer donor materials and device performance, not enough attention has been paid toward the crystallinity problem. Herein, the structure and crystallinity of the representative polymer donor materials and the corresponding device properties have been briefly reviewed. Furthermore, several typical methods for controlling the crystallinity of materials have been summarized and illustrated as well. Moreover, the obstacles lying in the way of successful commercialization of such polymer solar cells have been systematically discussed. The in-depth interpretation of the crystallinity of the polymer donors in this article may stimulate novel ideas in material design and device fabrication.
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Affiliation(s)
- Dingding Qiu
- Chinese Academy of Sciences Key Laboratory of Nanosystem and Hierarchical Fabrication, Chinese Academy of Sciences Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Muhammad Abdullah Adil
- Chinese Academy of Sciences Key Laboratory of Nanosystem and Hierarchical Fabrication, Chinese Academy of Sciences Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Kun Lu
- Chinese Academy of Sciences Key Laboratory of Nanosystem and Hierarchical Fabrication, Chinese Academy of Sciences Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
| | - Zhixiang Wei
- Chinese Academy of Sciences Key Laboratory of Nanosystem and Hierarchical Fabrication, Chinese Academy of Sciences Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, China
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10
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Firdaus Y, Le Corre VM, Karuthedath S, Liu W, Markina A, Huang W, Chattopadhyay S, Nahid MM, Nugraha MI, Lin Y, Seitkhan A, Basu A, Zhang W, McCulloch I, Ade H, Labram J, Laquai F, Andrienko D, Koster LJA, Anthopoulos TD. Long-range exciton diffusion in molecular non-fullerene acceptors. Nat Commun 2020; 11:5220. [PMID: 33060574 PMCID: PMC7562871 DOI: 10.1038/s41467-020-19029-9] [Citation(s) in RCA: 88] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 09/16/2020] [Indexed: 11/10/2022] Open
Abstract
The short exciton diffusion length associated with most classical organic semiconductors used in organic photovoltaics (5-20 nm) imposes severe limits on the maximum size of the donor and acceptor domains within the photoactive layer of the cell. Identifying materials that are able to transport excitons over longer distances can help advancing our understanding and lead to solar cells with higher efficiency. Here, we measure the exciton diffusion length in a wide range of nonfullerene acceptor molecules using two different experimental techniques based on photocurrent and ultrafast spectroscopy measurements. The acceptors exhibit balanced ambipolar charge transport and surprisingly long exciton diffusion lengths in the range of 20 to 47 nm. With the aid of quantum-chemical calculations, we are able to rationalize the exciton dynamics and draw basic chemical design rules, particularly on the importance of the end-group substituent on the crystal packing of nonfullerene acceptors.
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Affiliation(s)
- Yuliar Firdaus
- King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), Physical Sciences and Engineering Division (PSE), Material Science and Engineering Program (MSE), 23955-6900, Thuwal, Kingdom of Saudi Arabia
| | - Vincent M Le Corre
- University of Groningen, Zernike Institute for Advanced Materials, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | - Safakath Karuthedath
- King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), Physical Sciences and Engineering Division (PSE), Material Science and Engineering Program (MSE), 23955-6900, Thuwal, Kingdom of Saudi Arabia
| | - Wenlan Liu
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Anastasia Markina
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Wentao Huang
- Department of Physics, Imperial College London, South Kensington, London, SW7 2AZ, UK
| | - Shirsopratim Chattopadhyay
- Electrical Engineering and Computer Science, Oregon State University, 3103 Kelley Engineering Center, Corvallis, OR, 97331, USA
| | - Masrur Morshed Nahid
- Department of Physics, Organic and Carbon Electronics Laboratories (ORaCEL), North Carolina State University, Raleigh, NC, 27695, USA
| | - Mohamad I Nugraha
- King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), Physical Sciences and Engineering Division (PSE), Material Science and Engineering Program (MSE), 23955-6900, Thuwal, Kingdom of Saudi Arabia
| | - Yuanbao Lin
- King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), Physical Sciences and Engineering Division (PSE), Material Science and Engineering Program (MSE), 23955-6900, Thuwal, Kingdom of Saudi Arabia
| | - Akmaral Seitkhan
- King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), Physical Sciences and Engineering Division (PSE), Material Science and Engineering Program (MSE), 23955-6900, Thuwal, Kingdom of Saudi Arabia
| | - Aniruddha Basu
- King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), Physical Sciences and Engineering Division (PSE), Material Science and Engineering Program (MSE), 23955-6900, Thuwal, Kingdom of Saudi Arabia
| | - Weimin Zhang
- King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), Physical Sciences and Engineering Division (PSE), Material Science and Engineering Program (MSE), 23955-6900, Thuwal, Kingdom of Saudi Arabia
| | - Iain McCulloch
- King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), Physical Sciences and Engineering Division (PSE), Material Science and Engineering Program (MSE), 23955-6900, Thuwal, Kingdom of Saudi Arabia
| | - Harald Ade
- Department of Physics, Organic and Carbon Electronics Laboratories (ORaCEL), North Carolina State University, Raleigh, NC, 27695, USA
| | - John Labram
- Electrical Engineering and Computer Science, Oregon State University, 3103 Kelley Engineering Center, Corvallis, OR, 97331, USA
| | - Frédéric Laquai
- King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), Physical Sciences and Engineering Division (PSE), Material Science and Engineering Program (MSE), 23955-6900, Thuwal, Kingdom of Saudi Arabia
| | - Denis Andrienko
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - L Jan Anton Koster
- University of Groningen, Zernike Institute for Advanced Materials, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.
| | - Thomas D Anthopoulos
- King Abdullah University of Science and Technology (KAUST), KAUST Solar Center (KSC), Physical Sciences and Engineering Division (PSE), Material Science and Engineering Program (MSE), 23955-6900, Thuwal, Kingdom of Saudi Arabia.
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11
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Nandi A, Manna B, Ghosh R. Interplay of exciton–excimer dynamics in 9,10-diphenylanthracene nanoaggregates and thin films revealed by time-resolved spectroscopic studies. Phys Chem Chem Phys 2019; 21:11193-11202. [DOI: 10.1039/c9cp01124b] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Effect of morphology and influence of two phenyl rings at 9 and 10 position of anthracene on exciton and excimer relaxation dynamics in solid state has been presented.
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Affiliation(s)
- Amitabha Nandi
- Radiation and Photochemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085
- India
- Homi Bhabha National Institute
| | - Biswajit Manna
- Radiation and Photochemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085
- India
| | - Rajib Ghosh
- Radiation and Photochemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085
- India
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12
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Krishnan Jagadamma L, McCarron LJ, Wiles AA, Savikhin V, Sajjad MT, Yazdani M, Rotello VM, Toney MF, Cooke G, Samuel IDW. Triptycene as a Supramolecular Additive in PTB7:PCBM Blends and Its Influence on Photovoltaic Properties. ACS APPLIED MATERIALS & INTERFACES 2018; 10:24665-24678. [PMID: 29932630 DOI: 10.1021/acsami.8b03114] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Additives play an important role in modifying the morphology and phase separation of donor and acceptor molecules in bulk heterojunction (BHJ) solar cells. Here, we report triptycene (TPC) as a small-molecule additive for supramolecular control of phase separation and concomitant improvement of the power conversion efficiency (PCE) of PTB7 donor and fullerene acceptor-based BHJ polymer solar cells. An overall 60% improvement in PCE is observed for both PTB7:PC61BM and PTB7:PC71BM blends. The improved photovoltaic (PV) performance can be attributed to three factors: (a) TPC-induced supramolecular interactions with donor:acceptor components in the blends to realize a nanoscale phase-separated morphology; (b) an increase in the charge transfer state energy that lowers the driving force for electron transfer from donor to acceptor molecules; and (c) an increase in the charge carrier mobility. An improvement in efficiency using TPC as a supramolecular additive has also been demonstrated for other BHJ blends such as PBDB-T:PC71BM and P3HT:PCBM, implying the wide applicability of this new additive molecule. A comparison of the photostability of TPC as an additive for PTB7:PCBM solar cells to that of the widely used 1,8-diiodooctane additive shows ∼30% higher retention of PV performance for the TPC-added solar cells after 34 h of AM 1.5G illumination. The results obtained suggest that the approach of using additives that can promote supramolecular interactions to modify the length scale of phase separation between donor and acceptor is very promising and can lead to the development of highly efficient and stable organic photovoltaics.
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Affiliation(s)
- Lethy Krishnan Jagadamma
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy , University of St. Andrews , St. Andrews , Fife KY16 9SS , U.K
| | - Liam J McCarron
- Glasgow Centre for Physical Organic Chemistry (GCPOC), WestCHEM, School of Chemistry , University of Glasgow , Glasgow G12 8QQ , U.K.
| | - Alan A Wiles
- Glasgow Centre for Physical Organic Chemistry (GCPOC), WestCHEM, School of Chemistry , University of Glasgow , Glasgow G12 8QQ , U.K.
| | - Victoria Savikhin
- Stanford Synchrotron Radiation Lightsource , SLAC National Accelerator Laboratory , 2575 Sand Hill Road , Menlo Park , California 94025 , United States
- Electrical Engineering Department , Stanford University , 350 Serra Mall , Stanford , California 94305 , United States
| | - Muhammad T Sajjad
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy , University of St. Andrews , St. Andrews , Fife KY16 9SS , U.K
| | - Mahdieh Yazdani
- Department of Chemistry , University of Massachusetts Amherst , 710 North Pleasant Street , Amherst , Massachusetts 01003 , United States
| | - Vincent M Rotello
- Department of Chemistry , University of Massachusetts Amherst , 710 North Pleasant Street , Amherst , Massachusetts 01003 , United States
| | - Michael F Toney
- Stanford Synchrotron Radiation Lightsource , SLAC National Accelerator Laboratory , 2575 Sand Hill Road , Menlo Park , California 94025 , United States
| | - Graeme Cooke
- Glasgow Centre for Physical Organic Chemistry (GCPOC), WestCHEM, School of Chemistry , University of Glasgow , Glasgow G12 8QQ , U.K.
| | - Ifor D W Samuel
- Organic Semiconductor Centre, SUPA, School of Physics and Astronomy , University of St. Andrews , St. Andrews , Fife KY16 9SS , U.K
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Cao B, He X, Sorge JB, Lalany A, Ahadi K, Afshar A, Olsen BC, Hauger TC, Mobarok MH, Li P, Cadien KC, Brett MJ, Luber EJ, Buriak JM. Understanding the Effects of a High Surface Area Nanostructured Indium Tin Oxide Electrode on Organic Solar Cell Performance. ACS APPLIED MATERIALS & INTERFACES 2017; 9:38706-38715. [PMID: 29022714 DOI: 10.1021/acsami.7b10610] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Organic solar cells (OSCs) are a complex assembly of disparate materials, each with a precise function within the device. Typically, the electrodes are flat, and the device is fabricated through a layering approach of the interfacial layers and photoactive materials. This work explores the integration of high surface area transparent electrodes to investigate the possible role(s) a three-dimensional electrode could take within an OSC, with a BHJ composed of a donor-acceptor combination with a high degree of electron and hole mobility mismatch. Nanotree indium tin oxide (ITO) electrodes were prepared via glancing angle deposition, structures that were previously demonstrated to be single-crystalline. A thin layer of zinc oxide was deposited on the ITO nanotrees via atomic layer deposition, followed by a self-assembled monolayer of C60-based molecules that was bound to the zinc oxide surface through a carboxylic acid group. Infiltration of these functionalized ITO nanotrees with the photoactive layer, the bulk heterojunction comprising PC71BM and a high hole mobility low band gap polymer (PDPPTT-T-TT), led to families of devices that were analyzed for the effect of nanotree height. When the height was varied from 0 to 50, 75, 100, and 120 nm, statistically significant differences in device performance were noted with the maximum device efficiencies observed with a nanotree height of 75 nm. From analysis of these results, it was found that the intrinsic mobility mismatch between the donor and acceptor phases could be compensated for when the electron collection length was reduced relative to the hole collection length, resulting in more balanced charge extraction and reduced recombination, leading to improved efficiencies. However, as the ITO nanotrees increased in height and branching, the decrease in electron collection length was offset by an increase in hole collection length and potential deleterious electric field redistribution effects, resulting in decreased efficiency.
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Affiliation(s)
- Bing Cao
- Department of Chemistry, University of Alberta , 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2, Canada
- National Institute for Nanotechnology, National Research Council Canada , 11421 Saskatchewan Drive, Edmonton, AB T6G 2M9, Canada
| | - Xiaoming He
- Department of Chemistry, University of Alberta , 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2, Canada
| | - Jason B Sorge
- Department of Electrical and Computer Engineering, University of Alberta , Edmonton, Alberta T6G 2 V4, Canada
| | - Abeed Lalany
- Department of Electrical and Computer Engineering, University of Alberta , Edmonton, Alberta T6G 2 V4, Canada
| | - Kaveh Ahadi
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, Alberta T6G 1H9, Canada
| | - Amir Afshar
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, Alberta T6G 1H9, Canada
| | - Brian C Olsen
- Department of Chemistry, University of Alberta , 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2, Canada
- National Institute for Nanotechnology, National Research Council Canada , 11421 Saskatchewan Drive, Edmonton, AB T6G 2M9, Canada
| | - Tate C Hauger
- Department of Chemistry, University of Alberta , 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2, Canada
- National Institute for Nanotechnology, National Research Council Canada , 11421 Saskatchewan Drive, Edmonton, AB T6G 2M9, Canada
| | - Md Hosnay Mobarok
- Department of Chemistry, University of Alberta , 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2, Canada
| | - Peng Li
- nanoFAB Centre, University of Alberta , Edmonton, Alberta T6G 2 V4, Canada
| | - Kenneth C Cadien
- Department of Chemical and Materials Engineering, University of Alberta , Edmonton, Alberta T6G 1H9, Canada
| | - Michael J Brett
- Department of Electrical and Computer Engineering, University of Alberta , Edmonton, Alberta T6G 2 V4, Canada
| | - Erik J Luber
- Department of Chemistry, University of Alberta , 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2, Canada
- National Institute for Nanotechnology, National Research Council Canada , 11421 Saskatchewan Drive, Edmonton, AB T6G 2M9, Canada
| | - Jillian M Buriak
- Department of Chemistry, University of Alberta , 11227 Saskatchewan Drive, Edmonton, AB T6G 2G2, Canada
- National Institute for Nanotechnology, National Research Council Canada , 11421 Saskatchewan Drive, Edmonton, AB T6G 2M9, Canada
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14
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Thomson SAJ, Niklas J, Mardis KL, Mallares C, Samuel IDW, Poluektov OG. Charge Separation and Triplet Exciton Formation Pathways in Small Molecule Solar Cells as Studied by Time-resolved EPR Spectroscopy. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2017; 121:22707-22719. [PMID: 29606993 PMCID: PMC5875436 DOI: 10.1021/acs.jpcc.7b08217] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Organic solar cells are a promising renewable energy technology, offering the advantages of mechanical flexibility and solution processability. An understanding of the electronic excited states and charge separation pathways in these systems is crucial if efficiencies are to be further improved. Here we use light induced electron paramagnetic resonance (LEPR) spectroscopy and density functional theory calculations (DFT) to study the electronic excited states, charge transfer (CT) dynamics and triplet exciton formation pathways in blends of the small molecule donors (DTS(FBTTh2)2, DTS(F2BTTh2)2, DTS(PTTh2)2, DTG(FBTTh2)2 and DTG(F2BTTh2)2) with the fullerene derivative PC61BM. Using high frequency EPR the g-tensor of the positive polaron on the donor molecules was determined. The experimental results are compared with DFT calculations which reveal that the spin density of the polaron is distributed over a dimer or trimer. Time-resolved EPR (TR-EPR) spectra attributed to singlet CT states were identified and the polarization patterns revealed similar charge separation dynamics in the four fluorobenzothiadiazole donors, while charge separation in the DTS(PTTh2)2 blend is slower. Using TR-EPR we also investigated the triplet exciton formation pathways in the blend. The polarization patterns reveal that the excitons originate from both intersystem crossing (ISC) and back electron transfer (BET) processes. The DTS(PTTh2)2 blend was found to contain substantially more triplet excitons formed by BET than the fluorobenzothiadiazole blends. The higher BET triplet exciton population in the DTS(PTTh2)2 blend is in accordance with the slower charge separation dynamics observed in this blend.
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Affiliation(s)
- Stuart A. J Thomson
- Organic Semiconductor Centre, SUPA, School of Physics & Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
| | - Jens Niklas
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Kristy L. Mardis
- Department of Chemistry and Physics, Chicago State University, Chicago, Illinois 60628, USA
| | - Christopher Mallares
- Department of Chemistry and Physics, Chicago State University, Chicago, Illinois 60628, USA
| | - Ifor D. W. Samuel
- Organic Semiconductor Centre, SUPA, School of Physics & Astronomy, University of St Andrews, St Andrews, KY16 9SS, UK
- Phone: +44 1334 463114
| | - Oleg G. Poluektov
- Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
- Phone: +1 630 2523546
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15
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Abstract
Electronic energy pooling via excited state (exciton) annihilation, primarily in organic systems, is reviewed in tutorial form. Cross-disciplinary terminologies and references are used and reference is made to the historical origins of the phenomena. Applications in organic photovoltaic and electroluminescent devices are addressed. Particular attention is paid to the kinetics of the processes involved; a standard format for all systems is developed. Within the organic materials framework, all triplet–triplet, triplet–singlet, and singlet–singlet annihilation processes are discussed. Examples from gas, liquid, and solid phase systems, including both homo- and hetero-species interactions, are employed. Particular attention is given to triplet–triplet annihilation processes in which product states other than the lowest excited singlet state are formed.
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Affiliation(s)
- Ronald P. Steer
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, SK S7N 5C9, Canada
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