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Highly Efficient Non‐Fullerene Polymer Solar Cells Enabled by Wide Bandgap Copolymers With Conjugated Selenyl Side Chains
Author(s) -
Li Zuojia,
Xu Xiaopeng,
Zhang Guangjun,
Yu Ting,
Li Ying,
Peng Qiang
Publication year - 2018
Publication title -
solar rrl
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.544
H-Index - 37
ISSN - 2367-198X
DOI - 10.1002/solr.201800186
Subject(s) - polymer solar cell , materials science , band gap , acceptor , homo/lumo , conjugated system , fullerene , open circuit voltage , copolymer , energy conversion efficiency , benzotriazole , crystallinity , polymer , side chain , optoelectronics , chemistry , organic chemistry , voltage , molecule , physics , quantum mechanics , metallurgy , composite material , condensed matter physics
In this work, the authors design and synthesize two novel wide bandgap copolymers based on selenophene substituted benzo[1,2‐b:4,5‐b']dithiophene (BDTSe) as the donor unit and fluorinated benzotriazole as the acceptor unit for high performance non‐fullerene polymer solar cells (NF‐PSCs). A larger maximum molar extinction coefficient ( ϵ ) of 8.54 × 10 4 M −1 cm −1 is achieved when introducing sulfur atom onto the two‐dimensional (2D) BDTSe units, which should realize the better complementary absorption with ITIC as the acceptor, leading to a higher J sc of 19.51 mA cm −2 . Furthermore, a lower highest occupied molecular orbital (HOMO) energy level with almost no change in bandgap can be also achieved after inserting the sulfur atoms, thus resulting in an enhanced open‐circuit voltage ( V oc ) of 0.84 V without sacrificing the short‐current density ( J sc ). In addition, the higher crystallinity and optimized morphology are found to be beneficial to more efficient exciton dissociation and charge transport, giving rise to a higher fill factor (FF) of 75.1% and an elevated power conversion efficiency (PCE) of 12.31%. The results indicate that the strategy of alkylthioselenyl side chains on the BDT unit for constructing the donor‐acceptor (D‐A) copolymer donor materials is an excellent approach for realizing highly efficient NF‐PSCs.