Effect of processing additive on the nanomorphology of a bulk heterojunction material.

Moon, Ji Sun; Takacs, Christopher J; Cho, Shinuk; Coffin, Robert C; Kim, Heejoo; Bazan, Guillermo C; Heeger, Alan J · Nano Lett · 2010

basic_science · Level V

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Abstract

The bulk heterojunction (BHJ) material Si-PDTBT:PC(70)BM is sensitive to the use of a small amount of 1-chloronaphthalene (CN) as a processing additive; CN as a cosolvent (e.g., 4% in chlorobenzene) causes in a factor of 2 increase in the power conversion efficiency of BHJ solar cells. The morphology of the BHJ material, prepared with and without the CN additive is studied with top-down transmission electron microscopy, cross-sectional transmission electron microscopy, and atomic force microscopy. The improved performance is the result of changes in the nanoscale morphology. Field-effect transistor measurements are consistent with the observed changes in morphology.