The role of connectivity in significant bandgap narrowing for fused-pyrene based non-fullerene acceptors toward high-efficiency organic solar cells

Shungang Liu, Wenyan Su, Xianshao Zou, Xiaoyan Du, Jiamin Cao*, Nong Wang, Xingxing Shen, Xinjian Geng, Zilong Tang, Arkady Yartsev, Maojie Zhang*, Wolfgang Gruber, Tobias Unruh, Ning Li, Donghong Yu*, Christoph J. Brabec, Ergang Wang*

*Kontaktforfatter

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

2 Citationer (Scopus)

Abstrakt

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[30,20-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[30,20-b0]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 cm2 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.
OriginalsprogEngelsk
TidsskriftJournal of Materials Chemistry A
Vol/bind8
Udgave nummer12
Sider (fra-til)5995-6003
Antal sider9
ISSN2050-7488
DOI
StatusUdgivet - 3 mar. 2020

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