23% enhanced efficiency of polymer solar cells processed with 1-chloronaphthalene as the solvent additive

Power conversion efficiency (PCE) of polymer solar cells fabricated with {4,8-bis(4,5-didecyl-2-thienyl)-benzo[1,2-b:4,5-b']dithiophene-alt-[4,9-bis(4-hexyl-2-thienyl)-naphtho[1,2-c:5,6-c']bis[1,2,5]thiadiazole-5,5-diyl]} (PBDT-DTNT) as the electron donor and [6,6]-phenyl C-71-butyric acid methyl ester (PC71 BM) as the electron acceptor was improved from 5.33% to 6.57% by adding 1% of 1-chloronaphthalene as the solvent additive into o-dichlorobenzene which was used as the solvent for both PBDT-DTNT and PC71BM. The enhanced PCE was attributed to optimized surface morphology and packed polymer chains leading to better phase separation morphology by the solvent additive. (C) 2012 Elsevier B.V. All rights reserved.