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Dai T, Nie Q, Lei P, Zhang B, Zhou J, Tang A, Wang H, Zeng Q, Zhou E. Effects of Halogenation on the Benzotriazole Unit of Non-Fullerene Acceptors in Organic Solar Cells with High Voltages. ACS APPLIED MATERIALS & INTERFACES 2021; 13:58994-59005. [PMID: 34851613 DOI: 10.1021/acsami.1c14317] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Non-fullerene acceptors (NFAs) can be simply divided into three categories: A-D-A, A-DA'D-A, and A2-A1-D-A1-A2 according to their chemical structures. Benefiting from the easily modified 1,1-dicyanomethylene-3-indanone end groups, the halogenation on the first two types of materials has been proved to be very effective to modulate their optoelectronic properties and improve their photovoltaic performance. Hence, in this work, we systematically investigate the effect of halogenation on the classic NFA molecule of BTA3, which has the linear A2-A1-D-A1-A2-type backbone. After fluorination and chlorination, F-BTA3 and Cl-BTA3 have similar optical band gaps but lower energy levels than BTA3. When blending with a linear copolymer PE25 composed of benzodifuran and chlorinated benzotriazole (BTA) according to "Same-A-Strategy", the corresponding VOC of the halogenated NFAs gradually decreases (1.13 V for F-BTA3 and 1.09 V for Cl-BTA3), compared with that of the BTA3-based device (VOC = 1.22 V). This tendency mainly comes from the lower lowest unoccupied molecular orbital energy levels due to the strong electron-withdrawing ability of halogen atoms and the larger nonradiative energy loss. However, the power conversion efficiencies of the halogenated materials are slightly improved, from 9.08% for PE25: BTA3 to 10.45% for PE25: F-BTA3 and 10.75% for PE25: Cl-BTA, with the nonhalogenated solvent tetrahydrofuran as the processing solvent. The improved photovoltaic performance of F-BTA3 and Cl-BTA3 should come from the higher carrier mobility, weaker bimolecular recombination, and higher fluorescence quenching rate. This study illustrates that halogenation on the A1 unit is a promising strategy for developing novel and effective A2-A1-D-A1-A2-type NFAs.
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Affiliation(s)
- Tingting Dai
- CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qingling Nie
- CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Peng Lei
- CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Bao Zhang
- CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China
- Henan Institute of Advanced Technology, Zhengzhou University, Zhengzhou 450003, China
| | - Jialing Zhou
- CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Ailing Tang
- CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Helin Wang
- CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Qingdao Zeng
- CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China
| | - Erjun Zhou
- CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
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