title: Processing additives for improved efficiency from bulk heterojunction solar cells.
abstract: Two criteria for processing additives introduced to control the morphology of bulk heterojunction (BHJ) materials for use in solar cells have been identified: (i) selective (differential) solubility of the fullerene component and (ii) higher boiling point than the host solvent. Using these criteria, we have investigated the class of 1,8-di(R)octanes with various functional groups (R) as processing additives for BHJ solar cells. Control of the BHJ morphology by selective solubility of the fullerene component is demonstrated using these high boiling point processing additives. The best results are obtained with R = Iodine (I). Using 1,8-diiodooctane as the processing additive, the efficiency of the BHJ solar cells was improved from 3.4% (for the reference device) to 5.1%.
authors.affiliation: Center for Polymers and Organic Solids, University of California at Santa Barbara, Santa Barbara, California 93106, USA.
authors.forename: Jae Kwan
authors.initials: JK
authors.lastname: Lee
authors.forename: Wan Li
authors.initials: WL
authors.lastname: Ma
authors.forename: Christoph J
authors.initials: CJ
authors.lastname: Brabec
authors.forename: Jonathan
authors.initials: J
authors.lastname: Yuen
authors.forename: Ji Sun
authors.initials: JS
authors.lastname: Moon
authors.forename: Jin Young
authors.initials: JY
authors.lastname: Kim
authors.forename: Kwanghee
authors.initials: K
authors.lastname: Lee
authors.forename: Guillermo C
authors.initials: GC
authors.lastname: Bazan
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Heeger