The role of connectivity in significant bandgap narrowing for fused-pyrene based non-fullerene acceptors toward high-efficiency organic solar cells
Journal article, 2020
Great attention has been paid to developing low bandgap non-fullerene acceptors (NFAs) for matching wide bandgap donor polymers to increase the photocurrent and therefore the power conversion efficiencies (PCEs) of NFA organic solar cells, while pyrene-core based acceptor-donor-acceptor (A-D-A) NFAs have been mainly reported via the 2,9-position connection due to their bisthieno[3′,2′-b']thienyl[a,h]pyrene fused via a five-membered ring bridge at the ortho-position of pyrene as the representative one named FPIC5, which has prohibited further narrowing their energy gap. Herein, an acceptor FPIC6 was exploited by creating the 1,8-position connection through fusing as bisthieno[3′,2′-b′]thienyl[f-g,m-n]pyrene linked at the bay-position via a six-membered bridge, with enhanced push-pull characteristics within such A-D-A structure. As a structural isomer of FPIC5, FPIC6 exhibited a much lower bandgap of 1.42 eV (1.63 eV for FPIC5). Therefore, the photocurrent and PCE of PTB7-Th:FPIC6 cells were improved to 21.50 mA cm-2 and 11.55%, respectively, due to the balanced mobilities, better photoluminescence quenching efficiency and optimized morphology, which are both ∼40% better than those of PTB7-Th:FPIC5 cells. Our results clearly proved that a pyrene fused core with 1,8-position connection with electron-withdrawing end groups instead of 2,9-position connection is an efficient molecular design strategy to narrow the optical bandgap and improve the photovoltaic performance of NFA based OSCs.
Author
Shungang Liu
Hunan University of Science and Technology
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
Wenyan Su
Soochow University
Xianshao Zou
Lund University
Xiaoyan Du
University of Erlangen-Nuremberg (FAU)
Jiamin Cao
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
Hunan University of Science and Technology
Nong Wang
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
Xingxing Shen
Hebei Normal University of Science and Technology
Xinjian Geng
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
Zilong Tang
Hunan University of Science and Technology
A. Yartsev
Lund University
Maojie Zhang
Soochow University
Wolfgang Gruber
University of Erlangen-Nuremberg (FAU)
Tobias Unruh
University of Erlangen-Nuremberg (FAU)
Ning Li
University of Erlangen-Nuremberg (FAU)
Donghong Yu
Sino-Danish Center for Education and Research Denmark
Aalborg University
Christoph J. Brabec
University of Erlangen-Nuremberg (FAU)
Ergang Wang
Chalmers, Chemistry and Chemical Engineering, Applied Chemistry
Zhengzhou University
Journal of Materials Chemistry A
20507488 (ISSN) 20507496 (eISSN)
Vol. 8 12 5995-6003Subject Categories
Polymer Chemistry
Materials Chemistry
Organic Chemistry
DOI
10.1039/d0ta00520g