P3HT-Based Ternary Polymer Solar Cells of Blend A-DA’D–A Structure Small-Molecule and Bis-Adducted Fullerene Derivatives as Acceptors with over 10% Efficiency

Highly efficient ternary polymer solar cells (PSCs) were prepared using a blend of the A-DA’D–A structure small-molecule narrow bandgap material ZY-4Cl and the side-chain fullerene derivative broad bandgap NC70BA as acceptors, with P3HT as the polymer donor. The P3HT:ZY-4Cl-based binary PSCs exhibited a power conversion efficiency (PCE) of 9.81%, a short-circuit current density (JSC) of 17.02 mA cm–2, an open-circuit voltage (VOC) of 0.879 V, and a fill factor (FF) of 65.58%. The optimized ternary PSCs (with a ratio of P3HT:ZY-4Cl/NC70BA of 1:1.2:0.15) achieved a PCE of over 10% (10.53%), a JSC of 18.10 mA cm–2, a VOC of 0.877 V, and an FF of 66.07%. The high PCE of the optimized ternary PSCs can be attributed to efficient short-wavelength light absorption and well-optimized phase separation, which enhances the JSC. Additionally, the hollow spherical structure of NC70BA connects the ZY-4Cl molecules, enhancing the molecular arrangement and crystallization of P3HT, thereby increasing the charge carrier mobility. The optimized ternary PSCs exhibit a significant enhancement in JSC and a slight increase in FF compared with the P3HT:ZY-4Cl binary PSCs.