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Stoltzfus DM, Donaghey JE, Armin A, Shaw PE, Burn PL, Meredith P. Charge Generation Pathways in Organic Solar Cells: Assessing the Contribution from the Electron Acceptor. Chem Rev 2016; 116:12920-12955. [DOI: 10.1021/acs.chemrev.6b00126] [Citation(s) in RCA: 180] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Dani M. Stoltzfus
- Centre for Organic Photonics & Electronics, The University of Queensland, St Lucia, QLD 4072 Australia
| | - Jenny E. Donaghey
- Centre for Organic Photonics & Electronics, The University of Queensland, St Lucia, QLD 4072 Australia
| | - Ardalan Armin
- Centre for Organic Photonics & Electronics, The University of Queensland, St Lucia, QLD 4072 Australia
| | - Paul E. Shaw
- Centre for Organic Photonics & Electronics, The University of Queensland, St Lucia, QLD 4072 Australia
| | - Paul L. Burn
- Centre for Organic Photonics & Electronics, The University of Queensland, St Lucia, QLD 4072 Australia
| | - Paul Meredith
- Centre for Organic Photonics & Electronics, The University of Queensland, St Lucia, QLD 4072 Australia
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Li W, Hendriks KH, Wienk MM, Janssen RAJ. Diketopyrrolopyrrole Polymers for Organic Solar Cells. Acc Chem Res 2016; 49:78-85. [PMID: 26693798 DOI: 10.1021/acs.accounts.5b00334] [Citation(s) in RCA: 229] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Conjugated polymers have been extensively studied for application in organic solar cells. In designing new polymers, particular attention has been given to tuning the absorption spectrum, molecular energy levels, crystallinity, and charge carrier mobility to enhance performance. As a result, the power conversion efficiencies (PCEs) of solar cells based on conjugated polymers as electron donor and fullerene derivatives as electron acceptor have exceeded 10% in single-junction and 11% in multijunction devices. Despite these efforts, it is notoriously difficult to establish thorough structure-property relationships that will be required to further optimize existing high-performance polymers to their intrinsic limits. In this Account, we highlight progress on the development and our understanding of diketopyrrolopyrrole (DPP) based conjugated polymers for polymer solar cells. The DPP moiety is strongly electron withdrawing and its polar nature enhances the tendency of DPP-based polymers to crystallize. As a result, DPP-based conjugated polymers often exhibit an advantageously broad and tunable optical absorption, up to 1000 nm, and high mobilities for holes and electrons, which can result in high photocurrents and good fill factors in solar cells. Here we focus on the structural modifications applied to DPP polymers and rationalize and explain the relationships between chemical structure and organic photovoltaic performance. The DPP polymers can be tuned via their aromatic substituents, their alkyl side chains, and the nature of the π-conjugated segment linking the units along the polymer chain. We show that these building blocks work together in determining the molecular conformation, the optical properties, the charge carrier mobility, and the solubility of the polymer. We identify the latter as a decisive parameter for DPP-based organic solar cells because it regulates the diameter of the semicrystalline DPP polymer fibers that form in the photovoltaic blends with fullerenes via solution processing. The width of these fibers and the photon energy loss, defined as the energy difference between optical band gap and open-circuit voltage, together govern to a large extent the quantum efficiency for charge generation in these blends and thereby the power conversion efficiency of the photovoltaic devices. Lowering the photon energy loss and maintaining a high quantum yield for charge generation is identified as a major pathway to enhance the performance of organic solar cells. This can be achieved by controlling the structural purity of the materials and further control over morphology formation. We hope that this Account contributes to improved design strategies of DPP polymers that are required to realize new breakthroughs in organic solar cell performance in the future.
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Affiliation(s)
- Weiwei Li
- Beijing
National Laboratory for Molecular Sciences, CAS Key Laboratory of
Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
- Molecular
Materials and Nanosystems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Koen H. Hendriks
- Molecular
Materials and Nanosystems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Martijn M. Wienk
- Molecular
Materials and Nanosystems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
- Dutch Institute for Fundamental Energy Research, De Zaale 20, 5612
AJ Eindhoven, The Netherlands
| | - René A. J. Janssen
- Molecular
Materials and Nanosystems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
- Dutch Institute for Fundamental Energy Research, De Zaale 20, 5612
AJ Eindhoven, The Netherlands
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Tamai Y, Ohkita H, Benten H, Ito S. Exciton Diffusion in Conjugated Polymers: From Fundamental Understanding to Improvement in Photovoltaic Conversion Efficiency. J Phys Chem Lett 2015; 6:3417-28. [PMID: 26269208 DOI: 10.1021/acs.jpclett.5b01147] [Citation(s) in RCA: 124] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Singlet exciton diffusion plays a central role in the photovoltaic conversion in organic photovoltaics (OPVs). Upon light absorption, singlet excitons are promptly generated in organic materials instead of charge carriers because the dielectric constant (εr) is small (∼3-4), which is in sharp contrast to inorganic and perovskite solar cells. In order to convert to charge carriers, excitons need to diffuse into an interface between electron donor and acceptor materials before deactivating to the ground state. Therefore, fundamental understanding of exciton diffusion dynamics is one of the most important issues to further improve OPVs. We highlight recent leading studies in this field and describe several approaches for efficient exciton harvesting at the interface in OPVs.
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Affiliation(s)
- Yasunari Tamai
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University , Katsura, Nishikyo, Kyoto 615-8510, Japan
| | - Hideo Ohkita
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University , Katsura, Nishikyo, Kyoto 615-8510, Japan
- Japan Science and Technology Agency (JST), PRESTO, 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
| | - Hiroaki Benten
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University , Katsura, Nishikyo, Kyoto 615-8510, Japan
| | - Shinzaburo Ito
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University , Katsura, Nishikyo, Kyoto 615-8510, Japan
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Di Nuzzo D, Viola D, Fischer FSU, Cerullo G, Ludwigs S, Da Como E. Enhanced Photogeneration of Polaron Pairs in Neat Semicrystalline Donor-Acceptor Copolymer Films via Direct Excitation of Interchain Aggregates. J Phys Chem Lett 2015; 6:1196-1203. [PMID: 26262971 DOI: 10.1021/acs.jpclett.5b00218] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We investigate the photogeneration of polaron pairs (PPs) in neat films of the semicrystalline donor-acceptor semiconducting copolymer PCPDTBT. Carefully selecting the solution-processing procedures, we obtain films with different amounts of crystallinity and interchain aggregation. We compare the photogeneration of PPs between the films by monitoring their photoinduced absorption in ultrafast pump-probe experiments, selectively exciting nonaggregated or aggregated polymer chains. The direct photoexcitation of interchain π-aggregates results in prompt (<100 fs) charge generation. Compared to the case where nonaggregated chains are excited, we find an 8-fold increase in the prompt PP to singlet-exciton ratio. We also show that highly crystalline lamellar nanostructures not containing π-stacked or any light-absorbing aggregates do not improve the efficiency of PP photogeneration. Our results show that light absorption from interchain aggregates is highly beneficial for charge photogeneration in semiconducting polymers and should be taken into account when optimizing film morphologies for photovoltaic devices.
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Affiliation(s)
- Daniele Di Nuzzo
- †Department of Physics, University of Bath, BA2 7AY Bath, United Kingdom
| | - Daniele Viola
- ‡Dipartimento di Fisica, IFN-CNR, Politecnico di Milano, 20133 Milano, Italy
| | - Florian S U Fischer
- §IPOC-Functional Polymers, University of Stuttgart, 70569 Stuttgart, Germany
| | - Giulio Cerullo
- ‡Dipartimento di Fisica, IFN-CNR, Politecnico di Milano, 20133 Milano, Italy
| | - Sabine Ludwigs
- §IPOC-Functional Polymers, University of Stuttgart, 70569 Stuttgart, Germany
| | - Enrico Da Como
- †Department of Physics, University of Bath, BA2 7AY Bath, United Kingdom
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Wang J, Zhang F, Zhang M, Wang W, An Q, Li L, Sun Q, Tang W, Zhang J. Optimization of charge carrier transport balance for performance improvement of PDPP3T-based polymer solar cells prepared using a hot solution. Phys Chem Chem Phys 2015; 17:9835-40. [DOI: 10.1039/c5cp00963d] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using a hot solution may prove to be an effective method to improve the charge carrier transport for high performance PSCs.
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Affiliation(s)
- Jian Wang
- Key Laboratory of Luminescence and Optical Information
- Ministry of Education
- Beijing Jiaotong University
- Beijing 100044
- People's Republic of China
| | - Fujun Zhang
- Key Laboratory of Luminescence and Optical Information
- Ministry of Education
- Beijing Jiaotong University
- Beijing 100044
- People's Republic of China
| | - Miao Zhang
- Key Laboratory of Luminescence and Optical Information
- Ministry of Education
- Beijing Jiaotong University
- Beijing 100044
- People's Republic of China
| | - Wenbin Wang
- Key Laboratory of Luminescence and Optical Information
- Ministry of Education
- Beijing Jiaotong University
- Beijing 100044
- People's Republic of China
| | - Qiaoshi An
- Key Laboratory of Luminescence and Optical Information
- Ministry of Education
- Beijing Jiaotong University
- Beijing 100044
- People's Republic of China
| | - Lingliang Li
- Key Laboratory of Luminescence and Optical Information
- Ministry of Education
- Beijing Jiaotong University
- Beijing 100044
- People's Republic of China
| | - Qianqian Sun
- Key Laboratory of Luminescence and Optical Information
- Ministry of Education
- Beijing Jiaotong University
- Beijing 100044
- People's Republic of China
| | - Weihua Tang
- Key Laboratory of Soft Chemistry and Functional Materials (Ministry of Education of China)
- Nanjing University of Science and Technology
- Nanjing 210094
- People's Republic of China
| | - Jian Zhang
- School of Materials Science and Engineering
- Guilin University of Electronic Technology
- Guilin 541004
- People's Republic of China
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Hedström S, Tao Q, Wang E, Persson P. Rational design of D–A1–D–A2 conjugated polymers with superior spectral coverage. Phys Chem Chem Phys 2015; 17:26677-89. [DOI: 10.1039/c5cp03753k] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Calculations and experiments elucidate factors governing how D–A1–D–A2 polymers offer fundamentally improved spectral coverage via allowed transitions to both acceptor LUMOs.
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Affiliation(s)
- Svante Hedström
- Division of Theoretical Chemistry
- Lund University
- S-221 00 Lund
- Sweden
| | - Qiang Tao
- Department of Chemistry and Chemical Engineering/Polymer Technology
- Chalmers University of Technology
- S-412 96 Göteborg
- Sweden
| | - Ergang Wang
- Department of Chemistry and Chemical Engineering/Polymer Technology
- Chalmers University of Technology
- S-412 96 Göteborg
- Sweden
| | - Petter Persson
- Division of Theoretical Chemistry
- Lund University
- S-221 00 Lund
- Sweden
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Manninen VM, Heiskanen JP, Pankov D, Kastinen T, Hukka TI, Hormi OEO, Lemmetyinen HJ. The effect of diketopyrrolopyrrole (DPP) group inclusion in p-cyanophenyl end-capped oligothiophene used as a dopant in P3HT:PCBM BHJ solar cells. Photochem Photobiol Sci 2014; 13:1456-68. [DOI: 10.1039/c4pp00207e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Synthesis and properties of DPP-(2TPhCN)2 dopant molecules, which absorb light and transfer energy to PC60BM, increasing the BHJ cell efficiency.
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Affiliation(s)
- V. M. Manninen
- Department of Chemistry and Bioengineering
- Tampere University of Technology
- Tampere, Finland
| | | | - D. Pankov
- Department of Chemistry
- FI-90014 University of Oulu
- Finland
| | - T. Kastinen
- Department of Chemistry and Bioengineering
- Tampere University of Technology
- Tampere, Finland
| | - T. I. Hukka
- Department of Chemistry and Bioengineering
- Tampere University of Technology
- Tampere, Finland
| | - O. E. O. Hormi
- Department of Chemistry
- FI-90014 University of Oulu
- Finland
| | - H. J. Lemmetyinen
- Department of Chemistry and Bioengineering
- Tampere University of Technology
- Tampere, Finland
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