Improved Carrier Dynamics and High Solar Cell Performance in Postadditive-Soaked PTB7:PC71BM Bulk Heterojunction Materials

Abstract

Improved performance of polymer-based solar cells based on PTB7:PC71BM composites has been obtained by using additive-soaking treatments on pristine bulk-heterojunction (BHJ) films. From analyses of the nanoscale morphologies, solar-cell-device performance, and photoluminescence (PL) characteristics, we found that the best performance predominantly resulted from improved exciton dissociation and enhanced electron transport after photoexcitation of the PC71BM phases. Our analyses showed that thinner PC71BM networks with high electron mobilities, which are ideal for polymer-based solar cells, could be fabricated by using postadditive-soaking treatments. Improved film morphologies and carrier dynamics of the additive-soaked BHJ films also led to increased device lifetimes.