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 NC 70 BA 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 ( J SC ) of 17.02 mA cm –2, an open-circuit voltage ( V OC ) of 0.879 V, and a fill factor (FF) of 65.58%. The optimized ternary PSCs (with a ratio of P3HT:ZY-4Cl/NC 70 BA of 1:1.2:0.15) achieved a PCE of over 10% (10.53%), a J SC of 18.10 mA cm –2, a V OC 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 J SC . Additionally, the hollow spherical structure of NC 70 BA 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 J SC and a slight increase in FF compared with the P3HT:ZY-4Cl binary PSCs.