Controlling molecular weight of a high efficiency donor-acceptor conjugated polymer and understanding its significant impact on photovoltaic properties.

Li, Wentao; Yang, Liqiang; Tumbleston, John R; Yan, Liang; Ade, Harald; You, Wei · Adv Mater · 2014

basic_science · Level V

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Abstract

The molecular weight (MW) of PBnDT-FTAZ can be precisely controlled by adjusting the stoichiometric ratio of the two monomers, following the Carothers equation. The study of a set of PBnDT-FTAZ polymers with different MWs reveals that the MW significantly influences the morphology and structural order of PBnDTFTAZ in its bulk heterojunction solar cells, with the highest efficiency (over 7%) achieved with the use of a MW of 40 000 g mol(-1) .