作者：(1) Weigang Jiang, Runnan Yu, Zhiyang Liu, Ruixiang Peng, Dongbo Mi, Ling Hong, Qiang Wei, Jianhui H
关键字：OPV
论文来源：期刊
发表时间：2017年
A novel small-molecule acceptor, (2,2′-((5E,5′E)-5,5′-((5,5′-(4,4,9,9-tetrakis(5-
hexylthiophen-2-yl)-4,9-dihydro-s-indaceno[1,2-b:5,6-b′]dithiophene-2,7-diyl)
bis(4-(2-ethylhexyl)thiophene-5,2-diyl))bis(methanylylidene)) bis(3-hexyl-
4-oxothiazolidine-5,2-diylidene))dimalononitrile (ITCN), end-capped with
electron-deficient 2-(3-hexyl-4-oxothiazolidin-2-ylidene)malononitrile groups,
is designed, synthesized, and used as the third component in fullerene-free
ternary polymer solar cells (PSCs). The cascaded energy-level structure enabled
by the newly designed acceptor is beneficial to the carrier transport and
separation. Meanwhile, the three materials show a complementary absorption
in the visible region, resulting in efficient light harvesting. Hence, the
PBDB-T:ITCN:IT-M ternary PSCs possess a high short-circuit current density
(Jsc) under an optimal weight ratio of donors and acceptors. Moreover, the
open-circuit voltage (Voc) of the ternary PSCs is enhanced with an increase
of the third acceptor ITCN content, which is attributed to the higher lowest
unoccupied molecular orbital energy level of ITCN than that of IT-M, thus
exhibits a higher Voc in PBDB-T:ITCN binary system. Ultimately, the ternary
PSCs achieve a power conversion efficiency of 12.16%, which is higher than
the PBDB-T:ITM-based PSCs (10.89%) and PBDB-T:ITCN-based ones (2.21%).
This work provides an effective strategy to improve the photovoltaic performance
of PSCs.