A liquid crystal material as the third component for ternary polymer solar cells with an efficiency of 10.83% and enhanced stability

Herein, a liquid crystal material, BTR, was elaborately selected as the third component to complement PTB7-Th for the fabrication of highly efficient ternary polymer solar cells (PSCs). Via incorporating 10 wt% BTR in their donors, the champion power conversion efficiency (PCE) of the PSCs increased from 10.08% to 10.83%, resulting from the enhanced short circuit current (J_SC) of 19.23 mA cm^-2 and fill factor (FF) of 72.21%. The small amount of incorporated BTR may prefer to distribute in the PTB7-Th networks and has good miscibility with PC₇₁BM. The excitons on BTR may dissociate into free charge carriers at the BTR/PC₇₁BM interfaces and also transfer their energy to PTB7-Th through Förster resonance energy transfer, resulting in improved exciton utilization. Moreover, the molecular arrangement and morphology of the active layers could be optimized by incorporating appropriate amount of BTR as a nucleating agent, also leading to enhanced stability of the ternary PSCs. The positive effects of BTR on the performance improvement of PSCs were confirmed from the inverted and conventional structures of the cells.