1
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Waketola AG, Hone FG, Geldasa FT, Genene Z, Mammo W, Tegegne NA. Enhancing the Performance of Wide-Bandgap Polymer-Based Organic Solar Cells through Silver Nanorod Integration. ACS OMEGA 2024; 9:8082-8091. [PMID: 38405528 PMCID: PMC10882593 DOI: 10.1021/acsomega.3c08386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 01/15/2024] [Accepted: 01/17/2024] [Indexed: 02/27/2024]
Abstract
Light trapping induced by the introduction of metallic nanoparticles has been shown to improve photo absorption in organic solar cells (OSCs). Researchers in the fields of plasmonics and organic photovoltaics work together to boost sunlight absorption and photon-electron interactions in order to improve device performance. In this contribution, an inverted OSC was fabricated by using indacenodithieno[3,2-b]thiophene-alt-2,2'-bithiazole (PIDTT-BTz) as a wide-band gap donor copolymer and (6,6)-phenyl-C71-butyric acid methyl ester (PC71BM) as an acceptor. Silver nanorods (Ag-NRs), synthesized by precipitation method, were embedded in the active layer of the solar cell. The device fabricated with 1 wt % Ag-NRs in the active layer showed a 26% improvement in power conversion efficiency (PCE) when exposed to 100 mW/cm2 simulated solar illumination. The role of Ag-NRs in the performance improvement of the OSCs was analyzed systematically using morphological, electrical, and optical characterization methods. The light trapping and exciton generation were improved due to the localized surface plasmon resonance (LSPR) activated in Ag-NRs in the form of longitudinal and transverse modes. The photoactive layers (PIDTT-BTz:PC71BM) with the incorporation of 0.5 and 1 wt % Ag-NR showed increased absorption, while the absorption with 1.5 wt % Ag-NRs appeared to be reduced in the wavelength range from 400 to 580 nm. Ag-NRs play a favorable role in exciton photogeneration and dissociation due to the two LSPR modes generated by the Ag-NRs. In the optimized device, the short-circuit current density (JSC) increased from 11.92 to 14.25 mA/cm2, resulting in an increase in the PCE from 3.94 to 4.93%, which is attributed to the improved light-trapping by LSPR using Ag-NRs.
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Affiliation(s)
- Alemayehu G. Waketola
- Department
Physics Education, Kotebe University of
Education, Addis
Ababa 31248, Ethiopia
- Department
of Physics, Addis Ababa University, Addis Ababa 1176, Ethiopia
| | - Fekadu G. Hone
- Department
of Physics, Addis Ababa University, Addis Ababa 1176, Ethiopia
| | - Fikadu T. Geldasa
- Department
of Applied Physics, Adama Science and Technology
University, P.O. Box 1888, Adama 302120, Ethiopia
| | - Zewdneh Genene
- Department
of Chemistry and Chemical Engineering, Chalmers
University of Technology, Goteborg SE412 96, Sweden
| | - Wendimagegn Mammo
- Department
of Chemistry, Addis Ababa University, Addis Ababa 33658, Ethiopia
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2
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Zong X, Yang Y, Yin S. The Energy Structure of Spin States in Reducing the Nonradiative Voltage Loss in Organic Solar Cells. J Phys Chem Lett 2023; 14:7490-7497. [PMID: 37581406 DOI: 10.1021/acs.jpclett.3c01918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
In organic solar cells (OSCs), the nonradiative voltage loss (ΔVnr) has been identified as a critical factor for the relatively lower open-circuit voltage. Under open-circuit conditions, most of the charge recombination processes occur via the triplet exciton state, underscoring the importance of the energy structures concerning the local exciton (LE) and charge transfer (CT) spin states. In this Letter, we propose a five-state model to explore the spin state energy structures to reduce ΔVnr. Our calculations reveal that, to minimize ΔVnr, the spin singlet state for LE should possess a lower energy than the triplet state, ES1 < ET1. In contrast, the energies of the CT spin states have a negligible effect on ΔVnr. We identify the best energy structure as ES1 < ET1 ∼ ECT1/CT3. Moreover, our calculations demonstrate that strong couplings between these spin states, particularly involving spin flip, can effectively mitigate ΔVnr. These findings present novel insights for the advancement of OSCs.
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Affiliation(s)
- Xin Zong
- School of Physics, Shandong University, Jinan 250100, People's Republic of China
| | - Yawen Yang
- School of Physics, Shandong University, Jinan 250100, People's Republic of China
| | - Sun Yin
- School of Physics, Shandong University, Jinan 250100, People's Republic of China
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3
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Lowrie W, Westbrook RJE, Guo J, Gonev HI, Marin-Beloqui J, Clarke TM. Organic photovoltaics: The current challenges. J Chem Phys 2023; 158:110901. [PMID: 36948814 DOI: 10.1063/5.0139457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/17/2023] Open
Abstract
Organic photovoltaics are remarkably close to reaching a landmark power conversion efficiency of 20%. Given the current urgent concerns regarding climate change, research into renewable energy solutions is crucially important. In this perspective article, we highlight several key aspects of organic photovoltaics, ranging from fundamental understanding to implementation, that need to be addressed to ensure the success of this promising technology. We cover the intriguing ability of some acceptors to undergo efficient charge photogeneration in the absence of an energetic driving force and the effects of the resulting state hybridization. We explore one of the primary loss mechanisms of organic photovoltaics-non-radiative voltage losses-and the influence of the energy gap law. Triplet states are becoming increasingly relevant owing to their presence in even the most efficient non-fullerene blends, and we assess their role as both a loss mechanism and a potential strategy to enhance efficiency. Finally, two ways in which the implementation of organic photovoltaics can be simplified are addressed. The standard bulk heterojunction architecture could be superseded by either single material photovoltaics or sequentially deposited heterojunctions, and the attributes of both are considered. While several important challenges still lie ahead for organic photovoltaics, their future is, indeed, bright.
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Affiliation(s)
- William Lowrie
- Department of Chemistry, University College London, Christopher Ingold Building, London WC1H 0AJ, United Kingdom
| | - Robert J E Westbrook
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Junjun Guo
- Department of Chemistry, University College London, Christopher Ingold Building, London WC1H 0AJ, United Kingdom
| | - Hristo Ivov Gonev
- Department of Chemistry, University College London, Christopher Ingold Building, London WC1H 0AJ, United Kingdom
| | - Jose Marin-Beloqui
- Departamento de Química Física, Universidad de Malaga, Campus Teatinos s/n, 29071 Málaga, Spain
| | - Tracey M Clarke
- Department of Chemistry, University College London, Christopher Ingold Building, London WC1H 0AJ, United Kingdom
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4
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Shi F, Guo P, Qiao X, Yao G, Zhang T, Lu Q, Wang Q, Wang X, Rikhsibaev J, Wang E, Zhang C, Kwon YW, Woo HY, Wu H, Hou J, Ma D, Armin A, Ma Y, Xia Y. A Nitroxide Radical Conjugated Polymer as an Additive to Reduce Nonradiative Energy Loss in Organic Solar Cells. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023:e2212084. [PMID: 36924360 DOI: 10.1002/adma.202212084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 02/23/2023] [Indexed: 05/17/2023]
Abstract
Nonfullerene-acceptor-based organic solar cells (NFA-OSCs) are now set off to the 20% power conversion efficiency milestone. To achieve this, minimizing all loss channels, including nonradiative photovoltage losses, seems a necessity. Nonradiative recombination, to a great extent, is known to be an inherent material property due to vibrationally induced decay of charge-transfer (CT) states or their back electron transfer to the triplet excitons. Herein, it is shown that the use of a new conjugated nitroxide radical polymer with 2,2,6,6-tetramethyl piperidine-1-oxyl side groups (GDTA) as an additive results in an improvement of the photovoltaic performance of NFA-OSCs based on different active layer materials. Upon the addition of GDTA, the open-circuit voltage (VOC ), fill factor (FF), and short-circuit current density (JSC ) improve simultaneously. This approach is applied to several material systems including state-of-the-art donor/acceptor pairs showing improvement from 15.8% to 17.6% (in the case of PM6:Y6) and from 17.5% to 18.3% (for PM6:BTP-eC9). Then, the possible reasons behind the observed improvements are discussed. The results point toward the suppression of the CT state to triplet excitons loss channel. This work presents a facile, promising, and generic approach to further improve the performance of NFA-OSCs.
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Affiliation(s)
- Furong Shi
- Organic Semiconductor Materials and Applied Technology Research Centre of Gansu Province, School of Materials Science and Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, P. R. China
| | - Pengzhi Guo
- Organic Semiconductor Materials and Applied Technology Research Centre of Gansu Province, School of Materials Science and Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, P. R. China
- National Green Coating Equipment and Technology Research Centre, Lanzhou Jiaotong University, Lanzhou, 730070, P. R. China
| | - Xianfeng Qiao
- State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, P. R. China
| | - Guo Yao
- National Laboratory of Solid-State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China
| | - Tao Zhang
- State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Qi Lu
- Organic Semiconductor Materials and Applied Technology Research Centre of Gansu Province, School of Materials Science and Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, P. R. China
| | - Qian Wang
- Organic Semiconductor Materials and Applied Technology Research Centre of Gansu Province, School of Materials Science and Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, P. R. China
| | - Xiaofeng Wang
- Organic Semiconductor Materials and Applied Technology Research Centre of Gansu Province, School of Materials Science and Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, P. R. China
| | - Jasurbek Rikhsibaev
- Organic Semiconductor Materials and Applied Technology Research Centre of Gansu Province, School of Materials Science and Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, P. R. China
| | - Ergang Wang
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Göteborg, SE-412 96, Sweden
| | - Chunfeng Zhang
- National Laboratory of Solid-State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing, 210093, P. R. China
| | - Young-Wan Kwon
- Department of Chemistry, KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, Republic of Korea
| | - Han Young Woo
- Department of Chemistry, KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, Republic of Korea
| | - Hongbin Wu
- State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, P. R. China
| | - Jianhui Hou
- State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory for Molecular Sciences CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry Chinese Academy of Sciences, Beijing, 100190, P. R. China
| | - Dongge Ma
- State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, P. R. China
| | - Ardalan Armin
- Sustainable Advanced Materials (Sêr SAM), Department of Physics, Swansea University, Singleton Park, Swansea, SA2 8PP, UK
| | - Yuguang Ma
- Organic Semiconductor Materials and Applied Technology Research Centre of Gansu Province, School of Materials Science and Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, P. R. China
| | - Yangjun Xia
- Organic Semiconductor Materials and Applied Technology Research Centre of Gansu Province, School of Materials Science and Engineering, Lanzhou Jiaotong University, Lanzhou, 730070, P. R. China
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5
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Ahmed AYA, Ike JN, Hamed MSG, Mola GT. Silver decorated magnesium doped photoactive layer for improved collection of photo‐generated current in polymer solar cell. J Appl Polym Sci 2023. [DOI: 10.1002/app.53697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Abdallah Y. A. Ahmed
- School of Chemistry and Physics University of KwaZulu‐Natal, Pietermaritzburg Campus King Edward Avenue, Scottsville South Africa
| | - Jude N. Ike
- School of Chemistry and Physics University of KwaZulu‐Natal, Pietermaritzburg Campus King Edward Avenue, Scottsville South Africa
| | - Mohammed S. G. Hamed
- School of Chemistry and Physics University of KwaZulu‐Natal, Pietermaritzburg Campus King Edward Avenue, Scottsville South Africa
| | - Genene Tessema Mola
- School of Chemistry and Physics University of KwaZulu‐Natal, Pietermaritzburg Campus King Edward Avenue, Scottsville South Africa
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6
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Pham TTD, Jung SJ, Oh CM, Yang JK, Lee D, Kidanemariam A, Muhammad A, Kim S, Shin TJ, Park J, Hwang IW, Park J. Conjugated Polymer Nanoparticles: Photothermal and Photodynamic Capabilities According to Molecular Ordering in Their Assembly Structures. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c01815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Thi-Thuy Duong Pham
- Department of Intelligent Energy and Industry, School of Chemical Engineering and Materials Science, Chung-Ang University, Seoul06974, Republic of Korea
| | - Seung-Jin Jung
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul03760, Republic of Korea
| | - Chang-Mok Oh
- Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, Gwangju61005, Republic of Korea
| | - Jin-Kyoung Yang
- Chemical and Biological Integrative Research Center, Korea Institute of Science and Technology (KIST), Seoul02792, Republic of Korea
| | - Dabin Lee
- Department of Intelligent Energy and Industry, School of Chemical Engineering and Materials Science, Chung-Ang University, Seoul06974, Republic of Korea
| | - Alemayehu Kidanemariam
- Department of Intelligent Energy and Industry, School of Chemical Engineering and Materials Science, Chung-Ang University, Seoul06974, Republic of Korea
| | - Arbanah Muhammad
- Department of Intelligent Energy and Industry, School of Chemical Engineering and Materials Science, Chung-Ang University, Seoul06974, Republic of Korea
| | - Sehoon Kim
- Chemical and Biological Integrative Research Center, Korea Institute of Science and Technology (KIST), Seoul02792, Republic of Korea
| | - Tae Joo Shin
- UNIST Central Research Facilities & School of Natural Science, Ulsan National Institute of Science and Technology (UNIST), Ulsan44919, Republic of Korea
| | - JaeHong Park
- Department of Chemistry and Nanoscience, Ewha Womans University, Seoul03760, Republic of Korea
| | - In-Wook Hwang
- Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, Gwangju61005, Republic of Korea
| | - Juhyun Park
- Department of Intelligent Energy and Industry, School of Chemical Engineering and Materials Science, Chung-Ang University, Seoul06974, Republic of Korea
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7
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Liu Z, Liu Z, Wang R, Zhang ZG, Wang J, Zhang C. Intersystem Crossing in Acceptor-Donor-Acceptor Type Organic Photovoltaic Molecules Promoted by Symmetry Breaking in Polar Environments. J Phys Chem Lett 2022; 13:10305-10311. [PMID: 36305820 DOI: 10.1021/acs.jpclett.2c03020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The intramolecular electron push-pulling effect has been widely applied to manipulate the excited states in organic photovoltaic (OPV) molecules toward efficient photocurrent generation in working devices with bias fields. However, the effect of field induced polar environments on the excited-state dynamics remains largely unexplored. Here, we investigate the polar environment effect on excited dynamics in acceptor-donor-acceptor type OPV molecules dissolved in solvents with different polarities. By combining ultrafast transient absorption spectroscopy and quantum chemical computation, we observe the stabilization of excited states induced by symmetry breaking in the polar solvent in the molecules exhibiting strong electron push-pulling effects. The stabilized excited states undergo faster intersystem crossing processes with reduced singlet-triplet energy gaps. The findings suggest that the dynamics of charge generation and recombination may be controlled by manipulating the polar environment and electron push-pulling effect to improve the device performance.
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Affiliation(s)
- Ziran Liu
- Key Laboratory of Oil and Gas Fine Chemicals, Ministry of Education & Xinjiang Uygur Autonomous Region, School of Chemical Engineering and Technology, Xinjiang University, Urumqi830046, China
| | - Zhixing Liu
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing210093, China
| | - Rui Wang
- College of Physics, Nanjing University of Aeronautics and Astronautics, and Key Laboratory of Aerospace Information Materials and Physics (NUAA), MIIT, Nanjing211106, China
| | - Zhi-Guo Zhang
- State Key Laboratory of Chemical Resource Engineering, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing100029, China
| | - Jide Wang
- Key Laboratory of Oil and Gas Fine Chemicals, Ministry of Education & Xinjiang Uygur Autonomous Region, School of Chemical Engineering and Technology, Xinjiang University, Urumqi830046, China
| | - Chunfeng Zhang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing210093, China
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8
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Yamanaka T, Nakanotani H, Adachi C. Significant role of spin-triplet state for exciton dissociation in organic solids. SCIENCE ADVANCES 2022; 8:eabj9188. [PMID: 35235344 PMCID: PMC8890716 DOI: 10.1126/sciadv.abj9188] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 01/03/2022] [Indexed: 06/01/2023]
Abstract
Clarification of the role of the spin state that initiates exciton dissociation is critical to attaining a fundamental understanding of the mechanism of organic photovoltaics. Although an excited spin-triplet state with an energy lower than that of excited spin-singlet state is disadvantageous in exciton dissociation, a small electron exchange integral results in small singlet-triplet energy splitting in some material systems. This energy splitting leads to a nearly isoenergetic alignment of both excited states, raising a question about the role of excited spin states in exciton dissociation. Herein, we show that the spin-triplet rather than the spin-singlet plays a critical role in the exciton dissociation that leads to the formation of free carriers. This result indicates that the spin-triplet inherently acts as an intermediate, leading to exciton dissociation. Thus, our demonstration provides a fundamental understanding of the role of excited spin states of organic molecular systems in photoinduced charge-carrier generation.
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Affiliation(s)
- Takahiko Yamanaka
- Central Research Laboratory, Hamamatsu Photonics K.K., 5000 Hirakuchi, Hamakita-ku, Hamamatsu, Shizuoka 434-8601, Japan
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Hajime Nakanotani
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
- International Institute for Carbon Neutral Energy Research (WPI-ICNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Chihaya Adachi
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
- International Institute for Carbon Neutral Energy Research (WPI-ICNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
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9
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Chaney TP, Levin AJ, Schneider SA, Toney MF. Scattering techniques for mixed donor-acceptor characterization in organic photovoltaics. MATERIALS HORIZONS 2022; 9:43-60. [PMID: 34797358 DOI: 10.1039/d1mh01219c] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Precise control of the complex morphology of organic photovoltaic bulk heterojunction (BHJ) active layers remains an important yet challenging approach for improving power conversion efficiency. Of particular interest are the interfacial regions between electron donor and acceptor molecules where charge separation and charge recombination occur. Often, these interfaces feature a molecularly mixed donor-acceptor phase. This mixed phase has been extensively studied in polymer:fullerene systems but is poorly understood in state-of-the-art polymer:non-fullerene acceptor blends. Accurate, quantitative characterization of this mixed phase is critical to unraveling its importance for charge separation and recombination processes within the BHJ. Here, we detail X-ray and neutron scattering characterization techniques and analysis methods to quantify the mixed phase within BHJ active layers. We then review the existing literature where these techniques have been successfully used on several different material systems and correlated to device performance. Finally, future challenges for characterizing non-fullerene acceptor systems are addressed, and emerging strategies are discussed.
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Affiliation(s)
- Thomas P Chaney
- Materials Science and Engineering, University of Colorado, Boulder, CO 80309, USA.
| | - Andrew J Levin
- Materials Science and Engineering, University of Colorado, Boulder, CO 80309, USA.
| | - Sebastian A Schneider
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Michael F Toney
- Materials Science and Engineering, University of Colorado, Boulder, CO 80309, USA.
- Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309, USA
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10
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The role of charge recombination to triplet excitons in organic solar cells. Nature 2021; 597:666-671. [PMID: 34588666 DOI: 10.1038/s41586-021-03840-5] [Citation(s) in RCA: 117] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 07/20/2021] [Indexed: 11/08/2022]
Abstract
The use of non-fullerene acceptors (NFAs) in organic solar cells has led to power conversion efficiencies as high as 18%1. However, organic solar cells are still less efficient than inorganic solar cells, which typically have power conversion efficiencies of more than 20%2. A key reason for this difference is that organic solar cells have low open-circuit voltages relative to their optical bandgaps3, owing to non-radiative recombination4. For organic solar cells to compete with inorganic solar cells in terms of efficiency, non-radiative loss pathways must be identified and suppressed. Here we show that in most organic solar cells that use NFAs, the majority of charge recombination under open-circuit conditions proceeds via the formation of non-emissive NFA triplet excitons; in the benchmark PM6:Y6 blend5, this fraction reaches 90%, reducing the open-circuit voltage by 60 mV. We prevent recombination via this non-radiative channel by engineering substantial hybridization between the NFA triplet excitons and the spin-triplet charge-transfer excitons. Modelling suggests that the rate of back charge transfer from spin-triplet charge-transfer excitons to molecular triplet excitons may be reduced by an order of magnitude, enabling re-dissociation of the spin-triplet charge-transfer exciton. We demonstrate NFA systems in which the formation of triplet excitons is suppressed. This work thus provides a design pathway for organic solar cells with power conversion efficiencies of 20% or more.
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11
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Chow PCY, Chan CCS, Ma C, Zou X, Yan H, Wong KS. Factors That Prevent Spin-Triplet Recombination in Non-fullerene Organic Photovoltaics. J Phys Chem Lett 2021; 12:5045-5051. [PMID: 34019416 DOI: 10.1021/acs.jpclett.1c01214] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Managing the dynamics of spin-triplet electronic states is crucial for achieving high-performance organic photovoltaics. Here we show that the replacement of fullerene with non-fullerene acceptor (NFA) molecules leads to suppression of triplet recombination and thus more efficient charge generation. This indicates that the relaxation of charges to the local triplet exciton state, although energetically allowed, is outcompeted by the thermally activated separation of interfacial charge-transfer excitons (CTEs) in the NFA-based system. By rationalizing our results with Marcus theory, we propose that triplet recombination in the fullerene system is driven by the small energy difference and strong electronic couplings between the CTE state and the lowest-lying triplet exciton state (T1) of fullerene acceptor molecules. In contrast, the large energy difference and small electronic couplings between these states in the NFA-based blends lead to sufficiently slow triplet relaxation rate compared to the charge separation rate (≪1010 s-1), thus preventing triplet recombination.
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Affiliation(s)
- Philip C Y Chow
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong 999077, China
| | - Christopher C S Chan
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China
| | - Chao Ma
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China
| | - Xinhui Zou
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China
| | - He Yan
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China
| | - Kam Sing Wong
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China
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12
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Wang R, Xu J, Fu L, Zhang C, Li Q, Yao J, Li X, Sun C, Zhang ZG, Wang X, Li Y, Ma J, Xiao M. Nonradiative Triplet Loss Suppressed in Organic Photovoltaic Blends with Fluoridated Nonfullerene Acceptors. J Am Chem Soc 2021; 143:4359-4366. [DOI: 10.1021/jacs.0c13352] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Rui Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Jianqiu Xu
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Lulu Fu
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Chunfeng Zhang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Qian Li
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Jia Yao
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- State key Laboratory of Chemical Resource Engineering, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Xiaojun Li
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Chenkai Sun
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Zhi-Guo Zhang
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
- State key Laboratory of Chemical Resource Engineering, College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, China
| | - Xiaoyong Wang
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Yongfang Li
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Jing Ma
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry of MOE, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Min Xiao
- National Laboratory of Solid State Microstructures, School of Physics, and Collaborative Innovation Center for Advanced Microstructures, Nanjing University, Nanjing 210093, China
- Department of Physics, University of Arkansas, Fayetteville, Arkansas 72701, United States
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13
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Ramirez I, Privitera A, Karuthedath S, Jungbluth A, Benduhn J, Sperlich A, Spoltore D, Vandewal K, Laquai F, Riede M. The role of spin in the degradation of organic photovoltaics. Nat Commun 2021; 12:471. [PMID: 33473110 PMCID: PMC7817674 DOI: 10.1038/s41467-020-20601-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 12/07/2020] [Indexed: 11/09/2022] Open
Abstract
Stability is now a critical factor in the commercialization of organic photovoltaic (OPV) devices. Both extrinsic stability to oxygen and water and intrinsic stability to light and heat in inert conditions must be achieved. Triplet states are known to be problematic in both cases, leading to singlet oxygen production or fullerene dimerization. The latter is thought to proceed from unquenched singlet excitons that have undergone intersystem crossing (ISC). Instead, we show that in bulk heterojunction (BHJ) solar cells the photo-degradation of C60 via photo-oligomerization occurs primarily via back-hole transfer (BHT) from a charge-transfer state to a C60 excited triplet state. We demonstrate this to be the principal pathway from a combination of steady-state optoelectronic measurements, time-resolved electron paramagnetic resonance, and temperature-dependent transient absorption spectroscopy on model systems. BHT is a much more serious concern than ISC because it cannot be mitigated by improved exciton quenching, obtained for example by a finer BHJ morphology. As BHT is not specific to fullerenes, our results suggest that the role of electron and hole back transfer in the degradation of BHJs should also be carefully considered when designing stable OPV devices.
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Affiliation(s)
- Ivan Ramirez
- Heliatek GmbH, Treidlerstrasse 3, 01139, Dresden, Germany.
| | - Alberto Privitera
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, OX1 3PU, Oxford, UK
| | - Safakath Karuthedath
- KAUST Solar Center (KSC), Physical Sciences and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), 23955-6900, Thuwai, Saudi Arabia
| | - Anna Jungbluth
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, OX1 3PU, Oxford, UK
| | - Johannes Benduhn
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics, Technische Universität Dresden, Nöthnitzer Strasse 61, 01187, Dresden, Germany
| | - Andreas Sperlich
- Experimental Physics 6, Julius Maximilian University of Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Donato Spoltore
- Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics, Technische Universität Dresden, Nöthnitzer Strasse 61, 01187, Dresden, Germany
| | - Koen Vandewal
- Institute for Materials Research (IMO-IMOMEC), Hasselt University, Wetenschapspark 1, 3590, Diepenbeek, Belgium
| | - Frédéric Laquai
- KAUST Solar Center (KSC), Physical Sciences and Engineering Division (PSE), King Abdullah University of Science and Technology (KAUST), 23955-6900, Thuwai, Saudi Arabia
| | - Moritz Riede
- Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, OX1 3PU, Oxford, UK.
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14
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Hinrichsen TF, Chan CCS, Ma C, Paleček D, Gillett A, Chen S, Zou X, Zhang G, Yip HL, Wong KS, Friend RH, Yan H, Rao A, Chow PCY. Long-lived and disorder-free charge transfer states enable endothermic charge separation in efficient non-fullerene organic solar cells. Nat Commun 2020; 11:5617. [PMID: 33154367 PMCID: PMC7645751 DOI: 10.1038/s41467-020-19332-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 09/28/2020] [Indexed: 11/17/2022] Open
Abstract
Organic solar cells based on non-fullerene acceptors can show high charge generation yields despite near-zero donor–acceptor energy offsets to drive charge separation and overcome the mutual Coulomb attraction between electron and hole. Here, we use time-resolved optical spectroscopy to show that free charges in these systems are generated by thermally activated dissociation of interfacial charge-transfer states that occurs over hundreds of picoseconds at room temperature, three orders of magnitude slower than comparable fullerene-based systems. Upon free electron–hole encounters at later times, both charge-transfer states and emissive excitons are regenerated, thus setting up an equilibrium between excitons, charge-transfer states and free charges. Our results suggest that the formation of long-lived and disorder-free charge-transfer states in these systems enables them to operate closely to quasi-thermodynamic conditions with no requirement for energy offsets to drive interfacial charge separation and achieve suppressed non-radiative recombination. Designing efficient organic solar cells is limited by the energy required to overcome the mutual Coulomb attraction between electron and hole. Here, the authors reveal long-lived and disorder-free charge-transfer states enable efficient endothermic charge separation in non-fullerene systems with marginal energy offset.
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Affiliation(s)
- Ture F Hinrichsen
- Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Christopher C S Chan
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay,, Hong Kong, China
| | - Chao Ma
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay,, Hong Kong, China
| | - David Paleček
- Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Alexander Gillett
- Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
| | - Shangshang Chen
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay,, Hong Kong, China
| | - Xinhui Zou
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay,, Hong Kong, China
| | - Guichuan Zhang
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, China
| | - Hin-Lap Yip
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou, 510640, China
| | - Kam Sing Wong
- Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay,, Hong Kong, China
| | - Richard H Friend
- Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK.
| | - He Yan
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay,, Hong Kong, China.
| | - Akshay Rao
- Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK.
| | - Philip C Y Chow
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay,, Hong Kong, China. .,Department of Mechanical Engineering, The University of Hong Kong, Pokfulam, Hong Kong, China.
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15
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Cassidy A, James RL, Dawes A, Field D. Crystallites and Electric Fields in Solid Ammonia. ChemistryOpen 2020; 9:983-990. [PMID: 33024652 PMCID: PMC7528761 DOI: 10.1002/open.202000118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/03/2020] [Indexed: 11/12/2022] Open
Abstract
Absorption spectra of vacuum-deposited films of ammonia have been obtained in the range 115 nm to 310 nm for a set of 15 deposition temperatures, Td, between 20 K and 80 K. Results focus upon the region 115 nm to 130 nm in overlapping D, E, F and G←X Rydberg transitions involving Wannier-Mott excitons. We identify two phases of ammonia, showing the solid to be polymorphic. Peak absorption wavelengths in the region of interest are found to shift to the red by 299 cm-1, for Td between 20 K to 50 K, and 1380 cm-1 for Td between 55 K to 80 K. Shifts provide evidence for the presence of spontaneously generated electric fields in these films, of values in excess of 108 V m-1 for Td of 20 K to 50 K to a few times 107 V m-1 for 55 K to 80 K. Results enable us to place a lower limit of 1.58 nm on the size of crystallites in the low temperature regime. This dimension represents 16 unit cells or 64 species, giving a more quantitative description than the nebulous term amorphous, as applied to solid ammonia. We also determine that crystallites formed in the high temperature regime contain, within ±20 %, 1688, 756 and 236 molecules of ammonia, respectively at Td of 65 K, 60 K and 55 K.
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Affiliation(s)
- Andrew Cassidy
- Department of Physics and AstronomyAarhus UniversityNy Munkegade 1208000AarhusDenmark
| | - Rachel L. James
- School of Physical SciencesThe Open UniversityWalton HallMilton KeynesMK7 6AAUK
| | - Anita Dawes
- School of Physical SciencesThe Open UniversityWalton HallMilton KeynesMK7 6AAUK
| | - David Field
- Department of Physics and AstronomyAarhus UniversityNy Munkegade 1208000AarhusDenmark
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16
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Yuan J, Zhang H, Zhang R, Wang Y, Hou J, Leclerc M, Zhan X, Huang F, Gao F, Zou Y, Li Y. Reducing Voltage Losses in the A-DA′D-A Acceptor-Based Organic Solar Cells. Chem 2020. [DOI: 10.1016/j.chempr.2020.08.003] [Citation(s) in RCA: 96] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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17
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Qin L, Liu X, Zhang X, Yu J, Yang L, Zhao F, Huang M, Wang K, Wu X, Li Y, Chen H, Wang K, Xia J, Lu X, Gao F, Yi Y, Huang H. Triplet Acceptors with a D-A Structure and Twisted Conformation for Efficient Organic Solar Cells. Angew Chem Int Ed Engl 2020; 59:15043-15049. [PMID: 32385920 PMCID: PMC7497160 DOI: 10.1002/anie.202006081] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Indexed: 11/09/2022]
Abstract
Triplet acceptors have been developed to construct high-performance organic solar cells (OSCs) as the long lifetime and diffusion range of triplet excitons may dissociate into free charges instead of net recombination when the energy levels of the lowest triplet state (T1 ) are close to those of charge-transfer states (3 CT). The current triplet acceptors were designed by introducing heavy atoms to enhance the intersystem crossing, limiting their applications. Herein, two twisted acceptors without heavy atoms, analogues of Y6, constructed with large π-conjugated core and D-A structure, were confirmed to be triplet materials, leading to high-performance OSCs. The mechanism of triplet excitons were investigated to show that the twisted and D-A structures result in large spin-orbit coupling (SOC) and small energy gap between the singlet and triplet states, and thus efficient intersystem crossing. Moreover, the energy level of T1 is close to 3 CT, facilitating the split of triplet exciton to free charges.
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Affiliation(s)
- Linqing Qin
- Center of Materials Science and Optoelectronics EngineeringCollege of Materials Science and Opto-Electronic Technology &, CAS Center for Excellence in Topological Quantum Computation &, CAS Key Laboratory of Vacuum PhysicsUniversity of Chinese Academy of SciencesBeijing100049P. R. China
| | - Xingzheng Liu
- Center of Materials Science and Optoelectronics EngineeringCollege of Materials Science and Opto-Electronic Technology &, CAS Center for Excellence in Topological Quantum Computation &, CAS Key Laboratory of Vacuum PhysicsUniversity of Chinese Academy of SciencesBeijing100049P. R. China
| | - Xin Zhang
- Center of Materials Science and Optoelectronics EngineeringCollege of Materials Science and Opto-Electronic Technology &, CAS Center for Excellence in Topological Quantum Computation &, CAS Key Laboratory of Vacuum PhysicsUniversity of Chinese Academy of SciencesBeijing100049P. R. China
| | - Jianwei Yu
- Department of Physics, Chemistry and Biology (IFM)Linköping University58183LinköpingSweden
| | - Lei Yang
- Center of Materials Science and Optoelectronics EngineeringCollege of Materials Science and Opto-Electronic Technology &, CAS Center for Excellence in Topological Quantum Computation &, CAS Key Laboratory of Vacuum PhysicsUniversity of Chinese Academy of SciencesBeijing100049P. R. China
| | - Fenggui Zhao
- Key Laboratory of Luminescence and Optical InformationMinistry of EducationSchool of ScienceBeijing Jiaotong UniversityBeijing100044P. R. China
| | - Miaofei Huang
- Beijing National Laboratory for Molecular SciencesCAS Key Laboratory of Organic Solids, CAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing100190P. R. China
| | - Kangwei Wang
- State Key Laboratory of Advanced Technology for Materials Synthesis and ProcessingCenter of Smart Materials and DevicesSchool of Chemistry, Chemical Engineering and Life ScienceWuhan University of TechnologyWuhan430070P. R. China
| | - Xiaoxi Wu
- Center of Materials Science and Optoelectronics EngineeringCollege of Materials Science and Opto-Electronic Technology &, CAS Center for Excellence in Topological Quantum Computation &, CAS Key Laboratory of Vacuum PhysicsUniversity of Chinese Academy of SciencesBeijing100049P. R. China
| | - Yuhao Li
- Department of PhysicsThe Chinese University of Hong KongNew TerritoriesHong KongP. R. China
| | - Hao Chen
- Center of Materials Science and Optoelectronics EngineeringCollege of Materials Science and Opto-Electronic Technology &, CAS Center for Excellence in Topological Quantum Computation &, CAS Key Laboratory of Vacuum PhysicsUniversity of Chinese Academy of SciencesBeijing100049P. R. China
| | - Kai Wang
- Key Laboratory of Luminescence and Optical InformationMinistry of EducationSchool of ScienceBeijing Jiaotong UniversityBeijing100044P. R. China
| | - Jianlong Xia
- State Key Laboratory of Advanced Technology for Materials Synthesis and ProcessingCenter of Smart Materials and DevicesSchool of Chemistry, Chemical Engineering and Life ScienceWuhan University of TechnologyWuhan430070P. R. China
| | - Xinhui Lu
- Department of PhysicsThe Chinese University of Hong KongNew TerritoriesHong KongP. R. China
| | - Feng Gao
- Department of Physics, Chemistry and Biology (IFM)Linköping University58183LinköpingSweden
| | - Yuanping Yi
- Beijing National Laboratory for Molecular SciencesCAS Key Laboratory of Organic Solids, CAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing100190P. R. China
| | - Hui Huang
- Center of Materials Science and Optoelectronics EngineeringCollege of Materials Science and Opto-Electronic Technology &, CAS Center for Excellence in Topological Quantum Computation &, CAS Key Laboratory of Vacuum PhysicsUniversity of Chinese Academy of SciencesBeijing100049P. R. China
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18
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Xu Y, Yao H, Ma L, Wang J, Hou J. Efficient charge generation at low energy losses in organic solar cells: a key issues review. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2020; 83:082601. [PMID: 32375132 DOI: 10.1088/1361-6633/ab90cf] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Light absorption generates strongly bound excitons in organic solar cells (OSCs). To obtain efficient charge generation, a large driving force is required, which causes a large energy loss (E loss) and severely hinders the improvement in the power conversion efficiencies (PCEs) of OSCs. Recently, the development of non-fullerene OSCs has seen great success, and the resulting OSCs can yield highly efficient charge generation with a negligible driving force, which raises a fundamental question about how the excitons split into free charges. From a chemical structure perspective, the molecular electrostatic potential differences between donors and acceptors may play a critical role in facilitating charge separation. Although the E loss caused by charge generation has been suppressed, charge recombination, particularly via non-radiative pathways, severely limits further improvements in the PCEs. In OSCs with negligible driving forces, the lowest excited state, a hybrid local exciton-charge transfer state, is believed to have a strong association with the non-radiative E loss. This review discusses the efficient charge generation at low E loss values in highly efficient OSCs and highlights the issues that should be tackled to further improve the PCEs to new levels (∼20%).
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Affiliation(s)
- Ye Xu
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China. University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
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19
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Qin L, Liu X, Zhang X, Yu J, Yang L, Zhao F, Huang M, Wang K, Wu X, Li Y, Chen H, Wang K, Xia J, Lu X, Gao F, Yi Y, Huang H. Triplet Acceptors with a D‐A Structure and Twisted Conformation for Efficient Organic Solar Cells. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202006081] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Linqing Qin
- Center of Materials Science and Optoelectronics Engineering College of Materials Science and Opto-Electronic Technology &, CAS Center for Excellence in Topological Quantum Computation &, CAS Key Laboratory of Vacuum Physics University of Chinese Academy of Sciences Beijing 100049 P. R. China
| | - Xingzheng Liu
- Center of Materials Science and Optoelectronics Engineering College of Materials Science and Opto-Electronic Technology &, CAS Center for Excellence in Topological Quantum Computation &, CAS Key Laboratory of Vacuum Physics University of Chinese Academy of Sciences Beijing 100049 P. R. China
| | - Xin Zhang
- Center of Materials Science and Optoelectronics Engineering College of Materials Science and Opto-Electronic Technology &, CAS Center for Excellence in Topological Quantum Computation &, CAS Key Laboratory of Vacuum Physics University of Chinese Academy of Sciences Beijing 100049 P. R. China
| | - Jianwei Yu
- Department of Physics, Chemistry and Biology (IFM) Linköping University 58183 Linköping Sweden
| | - Lei Yang
- Center of Materials Science and Optoelectronics Engineering College of Materials Science and Opto-Electronic Technology &, CAS Center for Excellence in Topological Quantum Computation &, CAS Key Laboratory of Vacuum Physics University of Chinese Academy of Sciences Beijing 100049 P. R. China
| | - Fenggui Zhao
- Key Laboratory of Luminescence and Optical Information Ministry of Education School of Science Beijing Jiaotong University Beijing 100044 P. R. China
| | - Miaofei Huang
- Beijing National Laboratory for Molecular Sciences CAS Key Laboratory of Organic Solids, CAS Research/Education Center for Excellence in Molecular Sciences Institute of Chemistry Chinese Academy of Sciences Beijing 100190 P. R. China
| | - Kangwei Wang
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Center of Smart Materials and Devices School of Chemistry, Chemical Engineering and Life Science Wuhan University of Technology Wuhan 430070 P. R. China
| | - Xiaoxi Wu
- Center of Materials Science and Optoelectronics Engineering College of Materials Science and Opto-Electronic Technology &, CAS Center for Excellence in Topological Quantum Computation &, CAS Key Laboratory of Vacuum Physics University of Chinese Academy of Sciences Beijing 100049 P. R. China
| | - Yuhao Li
- Department of Physics The Chinese University of Hong Kong New Territories Hong Kong P. R. China
| | - Hao Chen
- Center of Materials Science and Optoelectronics Engineering College of Materials Science and Opto-Electronic Technology &, CAS Center for Excellence in Topological Quantum Computation &, CAS Key Laboratory of Vacuum Physics University of Chinese Academy of Sciences Beijing 100049 P. R. China
| | - Kai Wang
- Key Laboratory of Luminescence and Optical Information Ministry of Education School of Science Beijing Jiaotong University Beijing 100044 P. R. China
| | - Jianlong Xia
- State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Center of Smart Materials and Devices School of Chemistry, Chemical Engineering and Life Science Wuhan University of Technology Wuhan 430070 P. R. China
| | - Xinhui Lu
- Department of Physics The Chinese University of Hong Kong New Territories Hong Kong P. R. China
| | - Feng Gao
- Department of Physics, Chemistry and Biology (IFM) Linköping University 58183 Linköping Sweden
| | - Yuanping Yi
- Beijing National Laboratory for Molecular Sciences CAS Key Laboratory of Organic Solids, CAS Research/Education Center for Excellence in Molecular Sciences Institute of Chemistry Chinese Academy of Sciences Beijing 100190 P. R. China
| | - Hui Huang
- Center of Materials Science and Optoelectronics Engineering College of Materials Science and Opto-Electronic Technology &, CAS Center for Excellence in Topological Quantum Computation &, CAS Key Laboratory of Vacuum Physics University of Chinese Academy of Sciences Beijing 100049 P. R. China
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20
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Han G, Hu T, Yi Y. Reducing the Singlet-Triplet Energy Gap by End-Group π-π Stacking Toward High-Efficiency Organic Photovoltaics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2000975. [PMID: 32329542 DOI: 10.1002/adma.202000975] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Revised: 03/09/2020] [Accepted: 04/02/2020] [Indexed: 06/11/2023]
Abstract
To improve the power conversion efficiencies for organic solar cells, it is necessary to enhance light absorption and reduce energy loss simultaneously. Both the lowest singlet (S1) and triplet (T1) excited states need to energertically approach the charge-transfer state to reduce the energy loss in exciton dissociation and by triplet recombination. Meanwhile, the S1 energy needs to be decreased to broaden light absorption. Therefore, it is imperative to reduce the singlet-triplet energy gap (ΔEST ), particularly for the narrow-bandgap materials that determine the device T1 energy. Although maximizing intramolecular push-pull effect can drastically decrease ΔEST , it inevitably results in weak oscillator strength and light absorption. Herein, large oscillator strength (≈3) and a moderate ΔEST (0.4-0.5 eV) are found for state-of-the-art A-D-A small-molecule acceptors (ITIC, IT-4F, and Y6) owing to modest push-pull effect. Importantly, end-group π-π stacking commonly in the films can substantially decrease the S1 energy by nearly 0.1 eV, but the T1 energy is hardly changed. The obtained reduction of ΔEST is crucial to effectively suppress triplet recombination and acquire small exciton dissociation driving force. Thus, end-group π-π stacking is an effective way to achieve both small energy loss and efficient light absorption for high-efficiency organic photovoltaics.
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Affiliation(s)
- Guangchao Han
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
| | - Taiping Hu
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy Sciences, Beijing, 100049, China
| | - Yuanping Yi
- Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy Sciences, Beijing, 100049, China
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21
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Karuthedath S, Gorenflot J, Melianas A, Kan Z, Kemerink M, Laquai F. Buildup of Triplet-State Population in Operating TQ1:PC 71BM Devices Does Not Limit Their Performance. J Phys Chem Lett 2020; 11:2838-2845. [PMID: 32202789 DOI: 10.1021/acs.jpclett.0c00756] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Triplet generation in organic solar cells has been considered a major loss channel. Determining the density of the triplet-state population in an operating device is challenging. Here, we employ transient absorption (TA) spectroscopy on the quinoxaline-thiophene copolymer TQ1 blended with PC71BM, quantify the transient charge and triplet-state densities, and parametrize their generation and recombination dynamics. The charge recombination parameters reproduce the experimentally measured current-voltage characteristics in charge carrier drift-diffusion simulations, and they yield the steady-state charge densities. We demonstrate that triplets are formed by both geminate and nongeminate recombination of charge carriers and decay primarily by triplet-triplet annihilation. Using the charge densities in the rate equations describing triplet-state dynamics, we find that triplet-state densities in devices are in the range of charge carrier densities. Despite this substantial triplet-state buildup, TQ1:PC71BM devices exhibit only moderate geminate recombination and significantly reduced nongeminate charge recombination, with reduction factors between 10-4 and 10-3 compared to Langevin recombination.
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Affiliation(s)
- Safakath Karuthedath
- Materials Science and Engineering Program (MSE), Physical Sciences and Engineering Division (PSE), KAUST Solar Center (KSC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Julien Gorenflot
- Materials Science and Engineering Program (MSE), Physical Sciences and Engineering Division (PSE), KAUST Solar Center (KSC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Armantas Melianas
- Department of Physics, Chemistry and Biology, Biomolecular and Organic Electronics, Center of Organic Electronics (COE), Linköping University, 58183 Linköping, Sweden
| | - Zhipeng Kan
- Materials Science and Engineering Program (MSE), Physical Sciences and Engineering Division (PSE), KAUST Solar Center (KSC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Martijn Kemerink
- Complex Materials and Devices, Department of Physics, Chemistry and Biology, Linköping University, 58183 Linköping, Sweden
| | - Frédéric Laquai
- Materials Science and Engineering Program (MSE), Physical Sciences and Engineering Division (PSE), KAUST Solar Center (KSC), King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
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22
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23
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Gibbons DJ, Farawar A, Mazzella P, Leroy-Lhez S, Williams RM. Making triplets from photo-generated charges: observations, mechanisms and theory. Photochem Photobiol Sci 2020; 19:136-158. [DOI: 10.1039/c9pp00399a] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Photo-excitation of electron donor–acceptor systems can lead to the generation of a charge separated state (CT). Sometimes the charge recombination occurs mainly to the local triplet excited state (T1). How does the spin flip?
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Affiliation(s)
- Dáire J. Gibbons
- Molecular Photonics Group
- Van't Hoff Institute for Molecular Sciences (HIMS)
- Universiteit van Amsterdam
- 1098 XH Amsterdam
- Netherlands
| | - Aram Farawar
- Molecular Photonics Group
- Van't Hoff Institute for Molecular Sciences (HIMS)
- Universiteit van Amsterdam
- 1098 XH Amsterdam
- Netherlands
| | - Paul Mazzella
- Molecular Photonics Group
- Van't Hoff Institute for Molecular Sciences (HIMS)
- Universiteit van Amsterdam
- 1098 XH Amsterdam
- Netherlands
| | - Stéphanie Leroy-Lhez
- PEIRENE – EA7500
- Faculty of Sciences and Technology – University of Limoges
- 87060 Limoges
- France
| | - René M. Williams
- Molecular Photonics Group
- Van't Hoff Institute for Molecular Sciences (HIMS)
- Universiteit van Amsterdam
- 1098 XH Amsterdam
- Netherlands
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24
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Van Landeghem M, Lenaerts R, Kesters J, Maes W, Goovaerts E. Impact of the donor polymer on recombination via triplet excitons in a fullerene-free organic solar cell. Phys Chem Chem Phys 2019; 21:22999-23008. [PMID: 31599899 DOI: 10.1039/c9cp03793d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The greater chemical tunability of non-fullerene acceptors enables fine-tuning of the donor-acceptor energy level offsets, a promising strategy towards increasing the open-circuit voltage in organic solar cells. Unfortunately, this approach could open an additional recombination channel for the charge-transfer (CT) state via a lower-lying donor or acceptor triplet level. In this work we investigate such electron and hole back-transfer mechanisms in fullerene-free solar cells incorporating the novel molecular acceptor 2,4-diCN-Ph-DTTzTz. The transition to the low-driving force regime is studied by comparing blends with well-established donor polymers P3HT and MDMO-PPV, which allows for variation of the energetic offsets at the donor-acceptor interface. Combining various optical spectroscopic techniques, the CT process and subsequent triplet formation are systematically investigated. Although both back-transfer mechanisms are found to be energetically feasible in both blends, markedly different triplet-mediated recombination processes are observed for the two systems. The kinetic suppression of electron back-transfer in the blend with P3HT suggests that energy losses due to triplet formation on the polymer can be avoided, regardless of favorable energetic alignment.
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Affiliation(s)
- Melissa Van Landeghem
- Physics Department, University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium.
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25
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Jain N, Bothra U, Moghe D, Sadhanala A, Friend RH, McNeill CR, Kabra D. Negative Correlation between Intermolecular vs Intramolecular Disorder in Bulk-Heterojunction Organic Solar Cells. ACS APPLIED MATERIALS & INTERFACES 2018; 10:44576-44582. [PMID: 30488688 DOI: 10.1021/acsami.8b14628] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
By varying the concentration of a solvent additive, we demonstrate the modulation of intermolecular (donor/acceptor (D/A) interface) and intramolecular (bulk) disorder in blends of the low-band gap polymer poly[2,6-(4,4-bis(2-ethylhexyl)-4 H-cyclopental[2,1- b;3,4- b']-dithiophene)- alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) blended with [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM). Using the solvent additive concentration of 1,8-diiodooctane (DIO) in the host-processing solvent, the disorder in the bulk and at the interface is studied in terms of Urbach energy, electroluminescence (EL) broadening, and EL quantum efficiency (ELQE). The Urbach energy varies from 80 to 39 meV for bulk and 39 to 51 meV for D/A interface. An interesting feature is that changes in the Urbach energy of the D/A interface are opposite to those of the Urbach energy of bulk; i.e., the disorder at the D/A interface increases as the disorder in the bulk decreases with increase in DIO concentration. Our study evidently suggested a negative correlation between intermolecular and intramolecular property in a bulk-heterojunction solar cell. Furthermore, scanning photocurrent microscopy measurements show that the effective hole transport length is double in magnitude for cells processed from 3 vol % DIO in comparison to that in cells processed from 0 vol %. This increase in effective hole transport length is explained by an increase in the delocalization of the electronic states involved in charge transport, as confirmed by dark J- V knee voltage, JSC and EU-bulk measurements. Henceforth, we provide a functional relationship between the additive-induced bulk-heterojunction morphology and the optoelectronic properties of PCPDTBT-based solar cells.
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Affiliation(s)
| | - Urvashi Bothra
- Department of Materials Science and Engineering , Monash University , Wellington Road , Clayton , VIC 3800 , Australia
| | | | - Aditya Sadhanala
- Optoelectronics Group, Cavendish Laboratory , University of Cambridge , Cambridge CB3 0HE , U.K
| | - Richard H Friend
- Optoelectronics Group, Cavendish Laboratory , University of Cambridge , Cambridge CB3 0HE , U.K
| | - Christopher R McNeill
- Department of Materials Science and Engineering , Monash University , Wellington Road , Clayton , VIC 3800 , Australia
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26
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Albes T, Gagliardi A. Charge Pair Separation Dynamics in Organic Bulk-Heterojunction Solar Cells. ADVANCED THEORY AND SIMULATIONS 2018. [DOI: 10.1002/adts.201800032] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Tim Albes
- Department of Electrical and Computer Engineering; Technical University of Munich; Arcisstr. 21 80333 Munich Germany
| | - Alessio Gagliardi
- Department of Electrical and Computer Engineering; Technical University of Munich; Arcisstr. 21 80333 Munich Germany
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27
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Gautam BR, Younts R, Carpenter J, Ade H, Gundogdu K. The Role of FRET in Non-Fullerene Organic Solar Cells: Implications for Molecular Design. J Phys Chem A 2018; 122:3764-3771. [DOI: 10.1021/acs.jpca.7b12807] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Bhoj R. Gautam
- Department of Physics and Organic and Carbon Electronics Laboratory, North Carolina State University, Raleigh, North Carolina 27695, United States
- Department of Chemistry and Physics, Fayetteville State University, Fayetteville, North Carolina 28301, United States
| | - Robert Younts
- Department of Physics and Organic and Carbon Electronics Laboratory, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Joshua Carpenter
- Department of Physics and Organic and Carbon Electronics Laboratory, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Harald Ade
- Department of Physics and Organic and Carbon Electronics Laboratory, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Kenan Gundogdu
- Department of Physics and Organic and Carbon Electronics Laboratory, North Carolina State University, Raleigh, North Carolina 27695, United States
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28
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Zhang G, Zhao J, Chow PCY, Jiang K, Zhang J, Zhu Z, Zhang J, Huang F, Yan H. Nonfullerene Acceptor Molecules for Bulk Heterojunction Organic Solar Cells. Chem Rev 2018; 118:3447-3507. [PMID: 29557657 DOI: 10.1021/acs.chemrev.7b00535] [Citation(s) in RCA: 581] [Impact Index Per Article: 96.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The bulk-heterojunction blend of an electron donor and an electron acceptor material is the key component in a solution-processed organic photovoltaic device. In the past decades, a p-type conjugated polymer and an n-type fullerene derivative have been the most commonly used electron donor and electron acceptor, respectively. While most advances of the device performance come from the design of new polymer donors, fullerene derivatives have almost been exclusively used as electron acceptors in organic photovoltaics. Recently, nonfullerene acceptor materials, particularly small molecules and oligomers, have emerged as a promising alternative to replace fullerene derivatives. Compared to fullerenes, these new acceptors are generally synthesized from diversified, low-cost routes based on building block materials with extraordinary chemical, thermal, and photostability. The facile functionalization of these molecules affords excellent tunability to their optoelectronic and electrochemical properties. Within the past five years, there have been over 100 nonfullerene acceptor molecules synthesized, and the power conversion efficiency of nonfullerene organic solar cells has increased dramatically, from ∼2% in 2012 to >13% in 2017. This review summarizes this progress, aiming to describe the molecular design strategy, to provide insight into the structure-property relationship, and to highlight the challenges the field is facing, with emphasis placed on most recent nonfullerene acceptors that demonstrated top-of-the-line photovoltaic performances. We also provide perspectives from a device point of view, wherein topics including ternary blend device, multijunction device, device stability, active layer morphology, and device physics are discussed.
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Affiliation(s)
- Guangye Zhang
- Department of Chemistry and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration & Reconstruction , Hong Kong University of Science and Technology (HKUST) , Clear Water Bay , Kowloon, Hong Kong , China.,HKUST-Shenzhen Research Institute , No. 9 Yuexing first RD, Hi-tech Park , Nanshan, Shenzhen 518057 , China
| | - Jingbo Zhao
- Department of Chemistry and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration & Reconstruction , Hong Kong University of Science and Technology (HKUST) , Clear Water Bay , Kowloon, Hong Kong , China
| | - Philip C Y Chow
- Department of Chemistry and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration & Reconstruction , Hong Kong University of Science and Technology (HKUST) , Clear Water Bay , Kowloon, Hong Kong , China.,HKUST-Shenzhen Research Institute , No. 9 Yuexing first RD, Hi-tech Park , Nanshan, Shenzhen 518057 , China
| | - Kui Jiang
- Department of Chemistry and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration & Reconstruction , Hong Kong University of Science and Technology (HKUST) , Clear Water Bay , Kowloon, Hong Kong , China.,HKUST-Shenzhen Research Institute , No. 9 Yuexing first RD, Hi-tech Park , Nanshan, Shenzhen 518057 , China
| | - Jianquan Zhang
- Department of Chemistry and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration & Reconstruction , Hong Kong University of Science and Technology (HKUST) , Clear Water Bay , Kowloon, Hong Kong , China.,HKUST-Shenzhen Research Institute , No. 9 Yuexing first RD, Hi-tech Park , Nanshan, Shenzhen 518057 , China
| | - Zonglong Zhu
- Department of Chemistry and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration & Reconstruction , Hong Kong University of Science and Technology (HKUST) , Clear Water Bay , Kowloon, Hong Kong , China
| | - Jie Zhang
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510640 , P. R. China
| | - Fei Huang
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510640 , P. R. China
| | - He Yan
- Department of Chemistry and Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration & Reconstruction , Hong Kong University of Science and Technology (HKUST) , Clear Water Bay , Kowloon, Hong Kong , China.,HKUST-Shenzhen Research Institute , No. 9 Yuexing first RD, Hi-tech Park , Nanshan, Shenzhen 518057 , China.,Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices , South China University of Technology , Guangzhou 510640 , P. R. China
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29
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Tamai Y, Fan Y, Kim VO, Ziabrev K, Rao A, Barlow S, Marder SR, Friend RH, Menke SM. Ultrafast Long-Range Charge Separation in Nonfullerene Organic Solar Cells. ACS NANO 2017; 11:12473-12481. [PMID: 29148715 DOI: 10.1021/acsnano.7b06575] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Rapid, long-range charge separation in polymer-fullerene organic solar cells (OSCs) enables electrons and holes to move beyond their Coulomb capture radius and overcome geminate recombination. Understanding the nature of charge generation and recombination mechanisms in efficient, nonfullerene-acceptor-based OSCs are critical to further improve device performance. Here we report charge dynamics in an OSC using a perylene diimide (PDI) dimer acceptor. We use transient absorption spectroscopy to track the time evolution of electroabsorption caused by the dipolar electric field generated between electron-hole pairs as they separate after ionization at the donor-acceptor interface. We show that charges separate rapidly (<1 ps) and that free charge carriers are generated very efficiently (∼90% quantum yield). However, in the PDI-based OSC, external charge extraction is impaired by faster nongeminate decay to the ground state and to lower-lying triplet states.
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Affiliation(s)
- Yasunari Tamai
- Cavendish Laboratory, Department of Physics, University of Cambridge , Cambridge CB3 0HE, United Kingdom
| | - Yeli Fan
- Center for Organic Photonics and Electronics and School of Chemistry and Biochemistry, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
| | - Vincent O Kim
- Cavendish Laboratory, Department of Physics, University of Cambridge , Cambridge CB3 0HE, United Kingdom
| | - Kostiantyn Ziabrev
- Center for Organic Photonics and Electronics and School of Chemistry and Biochemistry, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
| | - Akshay Rao
- Cavendish Laboratory, Department of Physics, University of Cambridge , Cambridge CB3 0HE, United Kingdom
| | - Stephen Barlow
- Center for Organic Photonics and Electronics and School of Chemistry and Biochemistry, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
| | - Seth R Marder
- Center for Organic Photonics and Electronics and School of Chemistry and Biochemistry, Georgia Institute of Technology , Atlanta, Georgia 30332-0400, United States
| | - Richard H Friend
- Cavendish Laboratory, Department of Physics, University of Cambridge , Cambridge CB3 0HE, United Kingdom
| | - S Matthew Menke
- Cavendish Laboratory, Department of Physics, University of Cambridge , Cambridge CB3 0HE, United Kingdom
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30
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Chen XK, Tsuchiya Y, Ishikawa Y, Zhong C, Adachi C, Brédas JL. A New Design Strategy for Efficient Thermally Activated Delayed Fluorescence Organic Emitters: From Twisted to Planar Structures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1702767. [PMID: 29044726 DOI: 10.1002/adma.201702767] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 08/16/2017] [Indexed: 05/24/2023]
Abstract
In the traditional molecular design of thermally activated delayed fluorescence (TADF) emitters composed of electron-donor and electron-acceptor moieties, achieving a small singlet-triplet energy gap (ΔEST ) in strongly twisted structures usually translates into a small fluorescence oscillator strength, which can significantly decrease the emission quantum yield and limit efficiency in organic light-emitting diode devices. Here, based on the results of quantum-chemical calculations on TADF emitters composed of carbazole donor and 2,4,6-triphenyl-1,3,5-triazine acceptor moieties, a new strategy is proposed for the molecular design of efficient TADF emitters that combine a small ΔEST with a large fluorescence oscillator strength. Since this strategy goes beyond the traditional framework of structurally twisted, charge-transfer type emitters, importantly, it opens the way for coplanar molecules to be efficient TADF emitters. Here, a new emitter, composed of azatriangulene and diphenyltriazine moieties, is theoretically designed, which is coplanar due to intramolecular H-bonding interactions. The synthesis of this hexamethylazatriangulene-triazine (HMAT-TRZ) emitter and its preliminary photophysical characterizations point to HMAT-TRZ as a potential efficient TADF emitter.
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Affiliation(s)
- Xian-Kai Chen
- Laboratory for Computational and Theoretical Chemistry of Advanced Materials, Division of Physical Science and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
| | - Youichi Tsuchiya
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
- Adachi Molecular Exciton Engineering Project, Japan Science and Technology Agency (JST), ERATO, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
| | - Yuma Ishikawa
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
| | - Cheng Zhong
- Laboratory for Computational and Theoretical Chemistry of Advanced Materials, Division of Physical Science and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
| | - Chihaya Adachi
- Center for Organic Photonics and Electronics Research (OPERA), Kyushu University, 744 Motooka, Nishi, Fukuoka, 819-0395, Japan
- Adachi Molecular Exciton Engineering Project, Japan Science and Technology Agency (JST), ERATO, 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
| | - Jean-Luc Brédas
- Laboratory for Computational and Theoretical Chemistry of Advanced Materials, Division of Physical Science and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Saudi Arabia
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31
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Chen YJ, Muñoz Caro GM, Aparicio S, Jiménez-Escobar A, Lasne J, Rosu-Finsen A, McCoustra MRS, Cassidy AM, Field D. Wannier-Mott Excitons in Nanoscale Molecular Ices. PHYSICAL REVIEW LETTERS 2017; 119:157703. [PMID: 29077429 DOI: 10.1103/physrevlett.119.157703] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Indexed: 06/07/2023]
Abstract
The absorption of light to create Wannier-Mott excitons is a fundamental feature dictating the optical and photovoltaic properties of low band gap, high permittivity semiconductors. Such excitons, with an electron-hole separation an order of magnitude greater than lattice dimensions, are largely limited to these semiconductors but here we find evidence of Wannier-Mott exciton formation in solid carbon monoxide (CO) with a band gap of >8 eV and a low electrical permittivity. This is established through the observation that a change of a few degrees K in deposition temperature can shift the electronic absorption spectra of solid CO by several hundred wave numbers, coupled with the recent discovery that deposition of CO leads to the spontaneous formation of electric fields within the film. These so-called spontelectric fields, here approaching 4×10^{7} V m^{-1}, are strongly temperature dependent. We find that a simple electrostatic model reproduces the observed temperature dependent spectral shifts based on the Stark effect on a hole and electron residing several nm apart, identifying the presence of Wannier-Mott excitons. The spontelectric effect in CO simultaneously explains the long-standing enigma of the sensitivity of vacuum ultraviolet spectra to the deposition temperature.
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Affiliation(s)
- Y-J Chen
- Department of Physics, National Central University, Jhongli District, Taoyuan City 32054, Taiwan
| | - G M Muñoz Caro
- Centro de Astrobiología (CSIC-INTA), Ctra. de Ajalvir, km 4, Torrejón de Ardoz, 28850 Madrid, Spain
| | - S Aparicio
- Instituto de Tecnologías Físicas y de la Información Leonardo Torres Quevedo, ITEFI (CSIC), c/Serrano 144, 28006 Madrid, Spain
| | - A Jiménez-Escobar
- INAF-Osservatorio Astronomico di Palermo, P.za Parlamento 1, 90134 Palermo, Italy
| | - J Lasne
- Laboratoire Interuniversitaire des Systèmes Atmosphériques (LISA), CNRS UMR 7583, Universités Paris-Est Créteil and Paris Diderot, 61 avenue du Général de Gaulle, 94010 Créteil cedex, France Current address: IMT Lille Douai, Univ. Lille, SAGE-Département Sciences de l'Atmosphère et Génie de l'Environnement, 59000 Lille, France
| | - A Rosu-Finsen
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - M R S McCoustra
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
| | - A M Cassidy
- Department of Physics and Astronomy, University of Aarhus, Aarhus DK-8000, Denmark
| | - D Field
- Department of Physics and Astronomy, University of Aarhus, Aarhus DK-8000, Denmark
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32
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Li X, Tang ML. Triplet transport in thin films: fundamentals and applications. Chem Commun (Camb) 2017; 53:4429-4440. [DOI: 10.1039/c7cc00861a] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
An overview of experimental and theoretical work on triplet energy transfer, with a focus on triplet transport in thin films.
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Affiliation(s)
- Xin Li
- Chemistry Department
- University of California
- Riverside
- USA
| | - Ming Lee Tang
- Chemistry Department
- University of California
- Riverside
- USA
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33
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Yu Z, Zhang Y, Jiang X, Li X, Lai J, Hu M, Elawad M, Gurzadyan GG, Yang X, Sun L. High-efficiency perovskite solar cells employing a conjugated donor–acceptor co-polymer as a hole-transporting material. RSC Adv 2017. [DOI: 10.1039/c7ra04611a] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In this work, we have successfully demonstrated that molecularly p-doping of donor–acceptor co-polymer PCPDTBT as an efficient hole-transporting material in perovskite solar cells with a decent power conversion efficiency of 15.1%.
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34
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Albes T, Gagliardi A. Influence of permittivity and energetic disorder on the spatial charge carrier distribution and recombination in organic bulk-heterojunctions. Phys Chem Chem Phys 2017; 19:20974-20983. [DOI: 10.1039/c7cp03513f] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Gaining insight into the spatial charge carrier distribution and its relation to geminate and nongeminate recombination in bulk-heterojunction organic solar cells.
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Affiliation(s)
- Tim Albes
- Department of Electrical and Computer Engineering
- Technical University of Munich
- 80333 Munich
- Germany
| | - Alessio Gagliardi
- Department of Electrical and Computer Engineering
- Technical University of Munich
- 80333 Munich
- Germany
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35
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Charge Carrier Generation, Recombination, and Extraction in Polymer–Fullerene Bulk Heterojunction Organic Solar Cells. ELEMENTARY PROCESSES IN ORGANIC PHOTOVOLTAICS 2017. [DOI: 10.1007/978-3-319-28338-8_11] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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36
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Menke SM, Sadhanala A, Nikolka M, Ran NA, Ravva MK, Abdel-Azeim S, Stern HL, Wang M, Sirringhaus H, Nguyen TQ, Brédas JL, Bazan GC, Friend RH. Limits for Recombination in a Low Energy Loss Organic Heterojunction. ACS NANO 2016; 10:10736-10744. [PMID: 27809478 DOI: 10.1021/acsnano.6b06211] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Donor-acceptor organic solar cells often show high quantum yields for charge collection, but relatively low open-circuit voltages (VOC) limit power conversion efficiencies to around 12%. We report here the behavior of a system, PIPCP:PC61BM, that exhibits very low electronic disorder (Urbach energy less than 27 meV), very high carrier mobilities in the blend (field-effect mobility for holes >10-2 cm2 V-1 s-1), and a very low driving energy for initial charge separation (50 meV). These characteristics should give excellent performance, and indeed, the VOC is high relative to the donor energy gap. However, we find the overall performance is limited by recombination, with formation of lower-lying triplet excitons on the donor accounting for 90% of the recombination. We find this is a bimolecular process that happens on time scales as short as 100 ps. Thus, although the absence of disorder and the associated high carrier mobility speeds up charge diffusion and extraction at the electrodes, which we measure as early as 1 ns, this also speeds up the recombination channel, giving overall a modest quantum yield of around 60%. We discuss strategies to remove the triplet exciton recombination channel.
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Affiliation(s)
- S Matthew Menke
- Department of Physics, Cavendish Laboratory, University of Cambridge , J.J. Thompson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Aditya Sadhanala
- Department of Physics, Cavendish Laboratory, University of Cambridge , J.J. Thompson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Mark Nikolka
- Department of Physics, Cavendish Laboratory, University of Cambridge , J.J. Thompson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Niva A Ran
- Center for Polymers and Organic Solids, University of California , Santa Barbara, California 93106, United States
| | - Mahesh Kumar Ravva
- Solar & Photovoltaics Engineering Research Center, Division of Physical Science and Engineering, King Abdullah University of Science and Technology , Thuwal 23955-6900, Saudi Arabia
| | - Safwat Abdel-Azeim
- Solar & Photovoltaics Engineering Research Center, Division of Physical Science and Engineering, King Abdullah University of Science and Technology , Thuwal 23955-6900, Saudi Arabia
| | - Hannah L Stern
- Department of Physics, Cavendish Laboratory, University of Cambridge , J.J. Thompson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Ming Wang
- Center for Polymers and Organic Solids, University of California , Santa Barbara, California 93106, United States
| | - Henning Sirringhaus
- Department of Physics, Cavendish Laboratory, University of Cambridge , J.J. Thompson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Thuc-Quyen Nguyen
- Center for Polymers and Organic Solids, University of California , Santa Barbara, California 93106, United States
| | - Jean-Luc Brédas
- Solar & Photovoltaics Engineering Research Center, Division of Physical Science and Engineering, King Abdullah University of Science and Technology , Thuwal 23955-6900, Saudi Arabia
| | - Guillermo C Bazan
- Center for Polymers and Organic Solids, University of California , Santa Barbara, California 93106, United States
| | - Richard H Friend
- Department of Physics, Cavendish Laboratory, University of Cambridge , J.J. Thompson Avenue, Cambridge CB3 0HE, United Kingdom
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37
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Analysis of Triplet Exciton Loss Pathways in PTB7:PC71BM Bulk Heterojunction Solar Cells. Sci Rep 2016; 6:29158. [PMID: 27380928 PMCID: PMC4933975 DOI: 10.1038/srep29158] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 06/15/2016] [Indexed: 02/03/2023] Open
Abstract
A strategy for increasing the conversion efficiency of organic photovoltaics has been to increase the VOC by tuning the energy levels of donor and acceptor components. However, this opens up a new loss pathway from an interfacial charge transfer state to a triplet exciton (TE) state called electron back transfer (EBT), which is detrimental to device performance. To test this hypothesis, we study triplet formation in the high performing PTB7:PC71BM blend system and determine the impact of the morphology-optimizing additive 1,8-diiodoctane (DIO). Using photoluminescence and spin-sensitive optically detected magnetic resonance (ODMR) measurements at low temperature, we find that TEs form on PC71BM via intersystem crossing from singlet excitons and on PTB7 via EBT mechanism. For DIO blends with smaller fullerene domains, an increased density of PTB7 TEs is observed. The EBT process is found to be significant only at very low temperature. At 300 K, no triplets are detected via ODMR, and electrically detected magnetic resonance on optimized solar cells indicates that TEs are only present on the fullerenes. We conclude that in PTB7:PC71BM devices, TE formation via EBT is impacted by fullerene domain size at low temperature, but at room temperature, EBT does not represent a dominant loss pathway.
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38
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Gao K, Miao J, Xiao L, Deng W, Kan Y, Liang T, Wang C, Huang F, Peng J, Cao Y, Liu F, Russell TP, Wu H, Peng X. Multi-Length-Scale Morphologies Driven by Mixed Additives in Porphyrin-Based Organic Photovoltaics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:4727-4733. [PMID: 27062394 DOI: 10.1002/adma.201505645] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2015] [Revised: 02/10/2016] [Indexed: 06/05/2023]
Abstract
A new category of deep-absorbing small molecules is developed. Optimized devices driven by mixed additives show a remarkable short-circuit current of ≈20 mA cm(-2) and a highest power conversion efficiency of 9.06%. A multi-length-scale morphology is formed, which is fully characterized by resonant soft X-ray scattering, high-angle annular dark film image transmission electron microscopy, etc.
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Affiliation(s)
- Ke Gao
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, China
| | - Jingsheng Miao
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, China
| | - Liangang Xiao
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, China
| | - Wanyuan Deng
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, China
| | - Yuanyuan Kan
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, China
| | - Tianxiang Liang
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, China
| | - Cheng Wang
- Advanced Light Source, Lawrence Berkeley National Lab, Berkeley, CA, 94720, USA
| | - Fei Huang
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, China
| | - Junbiao Peng
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, China
| | - Yong Cao
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, China
| | - Feng Liu
- Materials Sciences Division, Lawrence Berkeley National Lab, Berkeley, CA, 94720, USA
| | - Thomas P Russell
- Materials Sciences Division, Lawrence Berkeley National Lab, Berkeley, CA, 94720, USA
- Polymer Science and Engineering Department, University of Massachusetts, Amherst, MA, 01003, USA
| | - Hongbin Wu
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, China
| | - Xiaobin Peng
- Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, 381 Wushan Road, Guangzhou, 510640, China
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39
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Street RA. Electronic Structure and Properties of Organic Bulk-Heterojunction Interfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:3814-3830. [PMID: 26603977 DOI: 10.1002/adma.201503162] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 07/30/2015] [Indexed: 05/28/2023]
Abstract
The electronic structure and physical mechanisms of carrier generation and transport in the organic bulk heterojunction are reviewed. The electronic structure describes the bands and band-tail states, the band alignment at the bulk-heterojunction interface, and the overall density-of-states model. The different electronic character of excitons and mobile charge is discussed, the former being highly molecular and the latter more delocalized. Dissociation of the exciton via the charge-transfer (CT) states is attributed to weak binding of the CT state arising from charge delocalization. Carrier transport and charge collection is strongly influenced by the presence of localized band-tail states. Recombination is attributed primarily to transitions from mobile carriers to band-tail or deep trap states.
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Affiliation(s)
- Robert A Street
- Palo Alto Research Center, 3333 Coyote Hill Road, Palo Alto, CA, 94304, USA
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40
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Andernach R, Utzat H, Dimitrov SD, McCulloch I, Heeney M, Durrant JR, Bronstein H. Synthesis and Exciton Dynamics of Triplet Sensitized Conjugated Polymers. J Am Chem Soc 2015. [DOI: 10.1021/jacs.5b06223] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rolf Andernach
- Centre
for Plastic Electronics, Imperial College London, London, United Kingdom SW7 2AZ
| | - Hendrik Utzat
- Centre
for Plastic Electronics, Imperial College London, London, United Kingdom SW7 2AZ
- Department
of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Stoichko D. Dimitrov
- Centre
for Plastic Electronics, Imperial College London, London, United Kingdom SW7 2AZ
| | - Iain McCulloch
- Centre
for Plastic Electronics, Imperial College London, London, United Kingdom SW7 2AZ
- SPERC, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
| | - Martin Heeney
- Centre
for Plastic Electronics, Imperial College London, London, United Kingdom SW7 2AZ
| | - James R. Durrant
- Centre
for Plastic Electronics, Imperial College London, London, United Kingdom SW7 2AZ
| | - Hugo Bronstein
- Department
of Chemistry, University College London, London, United Kingdom WC1H 0AJ
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41
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Spin-dependent charge transfer state design rules in organic photovoltaics. Nat Commun 2015; 6:6415. [DOI: 10.1038/ncomms7415] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 01/27/2015] [Indexed: 11/09/2022] Open
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42
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Chow PCY, Bayliss SL, Lakhwani G, Greenham NC, Friend RH. In situ optical measurement of charge transport dynamics in organic photovoltaics. NANO LETTERS 2015; 15:931-935. [PMID: 25585168 DOI: 10.1021/nl503687u] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We present a novel experimental approach which allows extraction of both spatial and temporal information on charge dynamics in organic solar cells. Using the wavelength dependence of the photonic structure in these devices, we monitor the change in spatial overlap between the photogenerated hole distribution and the optical probe profile as a function of time. In a model system we find evidence for a buildup of the photogenerated hole population close to the hole-extracting electrode on a nanosecond time scale and show that this can limit charge transport through space-charge effects under operating conditions.
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Affiliation(s)
- Philip C Y Chow
- Cavendish Laboratory, University of Cambridge , J. J. Thomson Avenue, Cambridge, United Kingdom
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43
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Andernach RE, Rossbauer S, Ashraf RS, Faber H, Anthopoulos TD, McCulloch I, Heeney M, Bronstein HA. Conjugated Polymer-Porphyrin Complexes for Organic Electronics. Chemphyschem 2015; 16:1223-30. [DOI: 10.1002/cphc.201402759] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2014] [Revised: 11/27/2014] [Indexed: 11/07/2022]
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44
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Chang SW, Kettle J, Waters H, Horie M. Cyclopentadithiophene–benzothiadiazole copolymers with permutations of repeating unit length and ratios; synthesis, optical and electrochemical properties and photovoltaic characteristics. RSC Adv 2015. [DOI: 10.1039/c5ra22946d] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Conjugated copolymers with varying ratios and lengths of cyclopentadithiophene to benzothiadiazole repeating units have been synthesized and characterised.
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Affiliation(s)
- Shu-Wei Chang
- Department of Chemical Engineering
- National Tsing-Hua University
- Hsinchu
- Taiwan
| | - Jeff Kettle
- School of Electronics
- Bangor University
- Gwynedd
- UK
| | - Huw Waters
- School of Electronics
- Bangor University
- Gwynedd
- UK
| | - Masaki Horie
- Department of Chemical Engineering
- National Tsing-Hua University
- Hsinchu
- Taiwan
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45
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Fazzi D, Barbatti M, Thiel W. Modeling ultrafast exciton deactivation in oligothiophenes via nonadiabatic dynamics. Phys Chem Chem Phys 2015; 17:7787-99. [DOI: 10.1039/c5cp00019j] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Nonadiabatic excited-state dynamics reveal the exciton relaxation processes in oligothiophenes. Ultrafast deactivation and exciton localization are predicted to occur within 200 fs, involving bond stretching, ring puckering, and torsional oscillations.
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Affiliation(s)
- Daniele Fazzi
- Max-Planck-Institut für Kohlenforschung
- D-45470 Mülheim an der Ruhr
- Germany
| | - Mario Barbatti
- Max-Planck-Institut für Kohlenforschung
- D-45470 Mülheim an der Ruhr
- Germany
| | - Walter Thiel
- Max-Planck-Institut für Kohlenforschung
- D-45470 Mülheim an der Ruhr
- Germany
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46
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Chow PCY, Albert-Seifried S, Gélinas S, Friend RH. Nanosecond intersystem crossing times in fullerene acceptors: implications for organic photovoltaic diodes. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2014; 26:4851-4. [PMID: 24902831 PMCID: PMC4515088 DOI: 10.1002/adma.201400846] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2014] [Revised: 04/14/2014] [Indexed: 05/19/2023]
Abstract
Triplet-exciton formation through intersystem crossing of photogenerated singlet excitons in fullerene acceptors can compete with charge generation in organic photovoltaic diodes. This article reports the intersystem crossing timescale (τISC ) of the most commonly used fullerene acceptors, PC60 BM and PC70 BM, in solutions and in spin-coated films. These times are on the nanosecond timescale, and are longer than the characteristic times for charge generation (τd ).
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Affiliation(s)
- Philip C Y Chow
- Cavendish Laboratory, University of CambridgeCB3 0HE, United Kingdom
| | | | - Simon Gélinas
- Cavendish Laboratory, University of CambridgeCB3 0HE, United Kingdom
| | - Richard H Friend
- Cavendish Laboratory, University of CambridgeCB3 0HE, United Kingdom
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47
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Bittner ER, Lankevich V, Gélinas S, Rao A, Ginger DA, Friend RH. How disorder controls the kinetics of triplet charge recombination in semiconducting organic polymer photovoltaics. Phys Chem Chem Phys 2014; 16:20321-8. [DOI: 10.1039/c4cp01776e] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Theoretical models of polymer–fullerene interfaces indicate that inhomogeneous broadening of fullerene energy levels introduces strong coupling between the interfacial3CT and nearby fullerene triplet excitons that can enhance the decay of these states in systems with higher degrees of energetic disorder.
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Affiliation(s)
| | | | - Simon Gélinas
- Cavendish laboratory
- University of Cambridge
- Cambridge, UK
| | - Akshay Rao
- Cavendish laboratory
- University of Cambridge
- Cambridge, UK
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