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A Narrow‐Bandgap n‐Type Polymer with an Acceptor–Acceptor Backbone Enabling Efficient All‐Polymer Solar Cells
Author(s) -
Sun Huiliang,
Yu Han,
Shi Yongqiang,
Yu Jianwei,
Peng Zhongxiang,
Zhang Xianhe,
Liu Bin,
Wang Junwei,
Singh Ranbir,
Lee Jaewon,
Li Yongchun,
Wei Zixiang,
Liao Qiaogan,
Kan Zhipeng,
Ye Long,
Yan He,
Gao Feng,
Guo Xugang
Publication year - 2020
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.202004183
Subject(s) - materials science , acceptor , band gap , polymer , photocurrent , organic solar cell , polymer solar cell , electron acceptor , homo/lumo , optoelectronics , photochemistry , molecule , organic chemistry , chemistry , composite material , physics , condensed matter physics
Abstract Narrow‐bandgap polymer semiconductors are essential for advancing the development of organic solar cells. Here, a new narrow‐bandgap polymer acceptor L14, featuring an acceptor–acceptor (A–A) type backbone, is synthesized by copolymerizing a dibrominated fused‐ring electron acceptor (FREA) with distannylated bithiophene imide. Combining the advantages of both the FREA and the A–A polymer, L14 not only shows a narrow bandgap and high absorption coefficient, but also low‐lying frontier molecular orbital (FMO) levels. Such FMO levels yield improved electron transfer character, but unexpectedly, without sacrificing open‐circuit voltage ( V oc ), which is attributed to a small nonradiative recombination loss ( E loss,nr ) of 0.22 eV. Benefiting from the improved photocurrent along with the high fill factor and V oc , an excellent efficiency of 14.3% is achieved, which is among the highest values for all‐polymer solar cells (all‐PSCs). The results demonstrate the superiority of narrow‐bandgap A–A type polymers for improving all‐PSC performance and pave a way toward developing high‐performance polymer acceptors for all‐PSCs.