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Twisted Alkylthiothien‐2‐yl Flanks and Extended Conjugation Length Synergistically Enhanced Photovoltaic Performance by Boosting Dielectric Constant and Carriers Kinetic Characteristics
Author(s) -
Guo Pengzhi,
Miao Wentao,
Liu Guanghong,
Tong Junfeng,
Liang Quanbin,
Zhang Youdan,
Li Miaomiao,
Li Jianfeng,
Wang Chenglong,
Wang Ergang,
Wu Hongbin,
Xia Yangjun
Publication year - 2021
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.202100030
Subject(s) - dielectric , kinetic energy , conjugated system , dipole , exciton , chemistry , charge carrier , energy conversion efficiency , side chain , materials science , stereochemistry , polymer , dissociation (chemistry) , crystallography , optoelectronics , physics , condensed matter physics , organic chemistry , quantum mechanics
Alternating conjugated polymers (CPs), derived from 2‐ethylhexylthiothiophen‐2‐yl (TS) or 2‐ethylhexylthiophen‐2‐yl (T) flanked dithieno[3,2‐ d :3,2‐ d ′]benzo[1,2‐ b :4,5‐ b ′]dithiophene (DTBDT) and diketopyrrolo‐pyrrole (DPP) termed as PDTBDT‐TS‐DPP and PDTBDT‐T‐DPP, are prepared and characterized. It is found that the PDTBDT‐TS‐DPP not only exhibits slightly deepening the highest occupied molecular orbital energy levels, and similar absorption, etc., but also presents higher dielectric constant ( ε r ) of 6.7 at 1 kHz in contrast to 3.2 for PDTBDT‐T‐DPP, which are even higher than those of 4.3 and 3.0 for PBDT‐TS‐DPP/PBDT‐T‐DPP generated from TS and T flanked benzo[1,2‐ b :4,5‐ b ʹ]dithiophene and DPP. Beyond that, the power conversion efficiency of 8.17% for the inverted photovoltaic devices from DPP‐based CPs, is achieved from PDTBDT‐TS‐DPP. The alkylthio side chains are used in the DTBDT of the larger twisting angles of TS flanks and longer conjugation length, synergistically contribute to the highest dipole moments, and then lead to the enhancement of ε r , thus devoted the modification exciton dissociation and charge carriers kinetic characteristics. To the authors’ knowledge, it is the first time to report that ε r of the CPs is connected with the twisting angle of flanks and conjugation length of the building blocks, besides the use of functional side chains and atoms.