Ternary small molecule solar cells exhibiting power conversion efficiency of 10.3%

The elaborately prepared BTR:PC₇₁BM based small molecule solar cells (SMSCs) exhibit a champion power conversion efficiency (PCE) of 9.37%, which should be among the highest values for previous reports on BTR:PC₇₁BM based SMSCs. Based on the optimized binary SMSCs, small molecule DIB-SQ was selected as the third component to fabricate ternary SMSCs. The champion PCE of 10.3% was achieved for ternary SMSCs with 6 wt% DIB-SQ in donors. An approximate 10% PCE improvement was obtained due to obviously increased short current density (J_SC) of 15.44 mA/cm² and fill factor (FF) of 73.8%. The main contribution of DIB-SQ can be summarized as the enhanced photon harvesting in long wavelength range and the optimized phase separation for better exciton dissociation and charge transport in ternary active layer. The results further demonstrate that ternary strategy should be an efficient and versatile method to improve the performance of SMSCs.