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Fused Tris(thienothiophene)‐Based Electron Acceptor with Strong Near‐Infrared Absorption for High‐Performance As‐Cast Solar Cells
Author(s) -
Li Tengfei,
Dai Shuixing,
Ke Zhifan,
Yang Langxuan,
Wang Jiayu,
Yan Cenqi,
Ma Wei,
Zhan Xiaowei
Publication year - 2018
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.201705969
Subject(s) - materials science , homo/lumo , acceptor , electron acceptor , absorption (acoustics) , molar absorptivity , organic solar cell , band gap , photochemistry , optoelectronics , optics , polymer , molecule , organic chemistry , chemistry , condensed matter physics , physics , composite material
A fused tris(thienothiophene) (3TT) building block is designed and synthesized with strong electron‐donating and molecular packing properties, where three thienothiophene units are condensed with two cyclopentadienyl rings. Based on 3TT, a fused octacylic electron acceptor (FOIC) is designed and synthesized, using strong electron‐withdrawing 2‐(5/6‐fluoro‐3‐oxo‐2,3‐dihydro‐1H‐inden‐1‐ylidene)‐malononitrile as end groups. FOIC exhibits absorption in 600–950 nm region peaked at 836 nm with extinction coefficient of up to 2 × 10 5 m –1 cm –1 , low bandgap of 1.32 eV, and high electron mobility of 1.2 × 10 –3 cm 2 V –1 s –1 . Compared with its counterpart ITIC3 based on indacenothienothiophene core, FOIC exhibits significantly upshifted highest occupied molecular orbital level, slightly downshifted lowest unoccupied molecular orbital level, significantly redshifted absorption, and higher mobility. The as‐cast organic solar cells (OSCs) based on blends of PTB7‐Th donor and FOIC acceptor without additional treatments exhibit power conversion efficiencies (PCEs) as high as 12.0%, which is much higher than that of PTB7‐Th: ITIC3 (8.09%). The as‐cast semitransparent OSCs based on the same blends show PCEs of up to 10.3% with an average visible transmittance of 37.4%.