Processing additives for improved efficiency from bulk heterojunction solar cells

Center for Polymers and Organic Solids, University of California at Santa Barbara, Santa Barbara, California 93106, USA.
Journal of the American Chemical Society (Impact Factor: 11.44). 04/2008; 130(11):3619-23. DOI: 10.1021/ja710079w
Source: PubMed

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%.

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