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Asymmetric Wide‐Bandgap Polymers Simultaneously Improve the Open‐Circuit Voltage and Short‐Circuit Current for Organic Photovoltaics
Author(s) -
Huang Shaorong,
Gu Wanying,
Chen Lie,
Liao Zhihui,
An Yongkang,
An Cunbin,
Chen Yiwang,
Hou Jianhui
Publication year - 2019
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.201800906
Subject(s) - photovoltaics , open circuit voltage , organic solar cell , materials science , current (fluid) , band gap , short circuit , voltage , polymer , optoelectronics , photovoltaic system , electrical engineering , engineering , composite material
A trade‐off between open‐circuit voltage ( V OC ) and high short‐circuit ( J SC ) becomes one of the most vital problems limiting further improvement in polymer solar cells' (PSCs) efficiency. In this work, two asymmetric polymer donors PBDT‐F‐2TC and PBDT‐SF‐2TC are designed and synthesized. When blended with a state‐of‐the‐art acceptor IT‐4F with low lowest‐unoccupied molecular orbital level, simultaneously high V OC (up to 0.94 V) and J SC (up to 20.73 mA cm −2 ) are obtained for both copolymers. Note that the V OC value of 0.94 V is the highest value of PSCs based on IT‐4F reported so far. The simultaneously improved V OC and J SC in resulting devices are discovered from the deep highest‐occupied molecular orbital levels (−5.5 to −5.7 eV) and the hyperchromic effect of the polymers, the small driving force, and the small energy loss during the charge transfer, due to the synergistic effect of asymmetric carboxylate unit and fluorine/sulfur atoms. More importantly, thanks to the asymmetric 2TC, both PBDT‐F‐2TC‐ and PBDT‐SF‐2TC‐based PSCs can be successfully processed by non‐halogenated solvent 1,2,4‐trimethylbenzene (TMB) to yield device efficiencies of 10.29% and 10.39%, respectively, which are the maximum values for non‐fullerene PSCs fabricated using the eco‐friendly solvent TMB.