Issue 1, 2018

Rational design of conjugated side chains for high-performance all-polymer solar cells

Abstract

With their rapid development in recent years, organic solar cells hold the exciting potential to be a groundbreaking form of solar harvesting technology. Among these, all-polymer solar cells (all-PSCs) stand out owing to various advantages such as complementary absorption and superior stability. However, the advance of all-PSCs has been greatly impeded by energy level mismatches and unfavorable morphology of the active layer. Here, we report a molecular engineering approach featuring asymmetrical 4-methoxythiophene/thiophene as conjugated side chains of the donor polymer to fine-tune the energy level alignment and phase separation. The corresponding polymer, namely, poly{4-[5-(2-ethylhexyl)-4-methoxythiophen-2-yl]-8-[5-(2-ethylhexyl)thiophen-2-yl]benzo[1,2-b:4,5-b′]dithiophene}-alt-[bis(5-thiophene-2-yl)-5,6-difluoro-2-(2-hexyldecyl)-2H-benzo[d][1,2,3]triazole-4,7-diyl] (PMOT32) exhibited a power conversion efficiency that exceeded 8.5% in all-PSCs with poly{[N,N′-bis(2-octyldodecyl)-1,4,5,8-naphthalenedicarboximide-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)} (N2200) as the acceptor. PMOT32:N2200 also maintained good photovoltaic performance when processed as a thick film or from non-halogenated solvents. Detailed comparisons with two other polymers with pure thiophene or 4-methoxythiophene as their side chains revealed how these side chains affected the photovoltaic performance via energy level alignment and phase separation.

Graphical abstract: Rational design of conjugated side chains for high-performance all-polymer solar cells

Supplementary files

Article information

Article type
Paper
Submitted
04 sep. 2017
Accepted
24 oct. 2017
First published
24 oct. 2017

Mol. Syst. Des. Eng., 2018,3, 103-112

Rational design of conjugated side chains for high-performance all-polymer solar cells

W. Huang, M. Li, F. Lin, Y. Wu, Z. Ke, X. Zhang, R. Ma, T. Yang, W. Ma and Y. Liang, Mol. Syst. Des. Eng., 2018, 3, 103 DOI: 10.1039/C7ME00088J

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