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Isomeric Effect of Wide Bandgap Polymer Donors with High Crystallinity to Achieve Efficient Polymer Solar Cells
Author(s) -
Xie Qian,
Liu Yikun,
Liao Xunfan,
Cui Yongjie,
Huang Shaorong,
Hu Lei,
He Qiannan,
Chen Lie,
Chen Yiwang
Publication year - 2020
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.202000454
Subject(s) - crystallinity , moiety , polymer , materials science , intramolecular force , band gap , homo/lumo , polymer solar cell , energy conversion efficiency , acceptor , absorption (acoustics) , crystallography , chemical physics , photochemistry , chemistry , stereochemistry , molecule , organic chemistry , optoelectronics , composite material , physics , condensed matter physics
Two highly crystalline polymer donors (PBTz4T2C‐a, PBTz4T2C‐b) with isomers (4T2C‐a, 4T2C‐b) are synthesized and applied in polymer solar cells. The developed polymers possess proper energy levels and complementary absorption with an efficient electron acceptor IT2F. It is interesting that the photophysical properties, crystallinity, and active layer morphology characteristic can be significantly changed by just slightly regulating the substitution position of the carboxylate groups. A series of simulation calculations of the two isomers are conducted in the geometry and electronic properties to explore the difference induced by the position adjustment of carboxylate groups. The results decipher that 4T2C‐b moiety features much stronger intramolecular noncovalent S⋯O interactions compared to that of 4T2C‐a, implying a higher coplanarity and much stronger crystallinity, and leading to excessive phase separation in PBTz4T2C‐b:IT2F blend film. In contrast, PBTz4T2C‐a with 4T2C‐a moiety exhibits suitable crystallinity with a lower the highest occupied molecular orbital level, higher film absorption coefficient, and charge mobilities, resulting in a much higher power conversion efficiency of 11.02%. This research demonstrates that the molecular conformation is of great importance to be considered for developing high‐performance polymer donors.