Enhanced performance of polymer solar cells by adding SnO2 nanoparticles in the photoactive layer

Polymer solar cells (PSCs) generally suffer energy losses due to low efficient exciton separation and carrier transfer within the active layer. In this paper, adding SnO2 nanoparticles (SNs) directly into the photoactive layer is proposed for reducing electron-hole recombination and thus facilitating electron transfer across the active layer. It is found that SN addition with appropriate amount can evidently enhance device performance with the power conversion efficiency from 2.67% to 3.39% mainly owing to the improved photocurrent density and fill factor. A systematic investigation confirms that the enhanced exciton separation and carrier transfer in the photoactive layer indeed plays the key role for performance improvement of the devices with appropriate SN addition. This work thus provides a simple strategy of reconciling the contradiction of effective carrier collection and efficient light absorption and thus improving the performance of PSCs.