A stability study of polymer solar cells using conjugated polymers with different donor or acceptor side chain patterns?

Journal of Materials Chemistry A Pub Date: 2016-10-12 DOI: 10.1039/C6TA07244E

Abstract

Improvement of the power conversion efficiency and long term stability remains to be of crucial importance for the further development of polymer solar cells (PSCs). Herein, a donor–acceptor copolymer based on 4,8-di(thiophene-2′-yl)benzo[1,2-b:4,5-b′]dithiophene (DTBDT) and 4,7-di(thiophene-2′-yl)benzo[c][1,2,5]thiadiazole (DTBT), specifically selected because of its suitability for roll-coating in the ambient environment, is investigated in terms of operational stability via partial exchange (5 or 10%) of the alkyl side chain on either the donor or the acceptor monomer with a 2-hydroxyethyl or 2-phenylethyl group. It is shown that the exchange of the hexyl chain on the DTBT moiety has a negative impact on the stability of the polymer as well as on the performance of the resulting PSCs. On the other hand, partial exchange of the 2-hexyldecyl side chain of the BDT unit by a 2-hydroxyethyl group results in an improved photochemical stability of the polymer film and a higher efficiency of 5.6% for the spin-coated PSC. The stability of roll-coated devices also slightly increases with the incorporation of 10% of either the 2-hydroxyethyl or 2-phenylethyl side chain.

Graphical abstract: A stability study of polymer solar cells using conjugated polymers with different donor or acceptor side chain patterns
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