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Influence of Alkyl Substitution Position on Wide‐Bandgap Polymers in High‐Efficiency Nonfullerene Polymer Solar Cells
Author(s) -
Guo Qing,
Li Wanbin,
Li Guangda,
Wang Kun,
Guo Xia,
Zhang Maojie,
Li Yongfang,
Wong WaiYeung
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.202000170
Subject(s) - alkyl , materials science , thermogravimetric analysis , side chain , polymer , conjugated system , polymer solar cell , band gap , energy conversion efficiency , acceptor , photovoltaic system , open circuit voltage , polymer chemistry , crystallography , chemistry , optoelectronics , organic chemistry , voltage , physics , electrical engineering , composite material , engineering , quantum mechanics , condensed matter physics
Two wide‐bandgap (WBG) conjugated polymers (PBPD‐ p and PBPD‐ m ) based on phenyl‐substituted benzodithiophene (BDT) with the different substitution position of the alkyl side chain and benzodithiophene‐4,8‐dione (BDD) units are designed and synthesized to investigate the influence of alkyl substitution position on the photovoltaic performance of polymers in polymer solar cells (PSCs). The thermogravimetric analysis, absorption spectroscopy, molecular energy level, X‐ray diffraction, charge transport and photovoltaic performance of the polymers are systematically studied. Compared with PBPD‐ p , PBPD‐ m exhibits a slight blue‐shift but a deeper highest occupied molecular orbital (HOMO) energy level, a tighter alkyl chain packing and a higher hole mobility. The PBPD‐ m ‐based PSCs blended with acceptor IT‐4F shows a higher power conversion efficiency (PCE) of 11.95% with a high open‐circuit voltage ( V oc ) of 0.88 V, a short‐circuit current density ( J sc ) of 19.76 mA cm −2 and a fill factor (FF) of 68.7% when compared with the PCE of 6.97% with a V oc of 0.81 V, a J sc of 15.97 mA cm −2 and an FF of 53.9% for PBPD‐ p . These results suggest that it is a feasible and effective strategy to optimize photovoltaic properties of WBG polymers by changing the substitution position of alkyl side chain in PSCs.