title: Effect of processing additive on the nanomorphology of a bulk heterojunction material.
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.
authors.affiliation: Center for Polymers and Organic Solids, University of California at Santa Barbara, Santa Barbara, California 93106-5090, USA.
authors.forename: Ji Sun
authors.initials: JS
authors.lastname: Moon
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Takacs
authors.forename: Shinuk
authors.initials: S
authors.lastname: Cho
authors.forename: Robert C
authors.initials: RC
authors.lastname: Coffin
authors.forename: Heejoo
authors.initials: H
authors.lastname: Kim
authors.forename: Guillermo C
authors.initials: GC
authors.lastname: Bazan
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Heeger