Improved photovoltaic performance of PTB7:PC71BM blend by thermal annealing and solvent vapor annealing.

The ordered aggregation of polymer donor and acceptor greatly affects the charge transport and charge recombination in polymer solar cells (PSCs). The post-production treatment of the active layer is the most widely applied strategy to improve the micro-distribution of polymer. Here, we demonstrated a simple method for high performance solar cell with thermal annealing (TA) and solvent vapor annealing (SVA). For the PSCs based on PTB7:PC71BM, the champion power conversion efficiencies (PCEs) were improved from 7.96 to 8.68% by employing TA + SVA and further to 8.86% with SVA + TA treatment. The enhanced PCEs of PSCs undergoing SVA + TA process are mainly attributed to the formation of a network phase separation structure with donor and acceptor phases penetrating each other and the improvement of the crystallinity of PTB7, while the improved photovoltaic performance with TA + SVA treatment is owing to the improved carrier mobility of blend films. Our work provides a useful strategy toward highly efficient PSCs without time-consuming and laborious fabrication procedures. [ABSTRACT FROM AUTHOR]