Ternary Solar Cells Based on the Benzo[1,2-b:4,5-b′]dithiophene-Containing Polymer and Small Molecule

Two benzo[1,2-b:4,5-b’]dithiophene and thiophene-based materials, a small molecule (SM-BDT) and a polymer (P-BDT), were synthesized and their photovoltaic properties were investigated by fabricating their binary and ternary cells. The introduction of the ternary blend system effectively enhanced device performance. The power conversion efficiency (PCE) of the ternary SM-BDT:P-BDT:[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) film (0.19%) was nearly double that of the pristine binary films of SM-BDT:PCBM and P-BDT:PCBM. The optical and electrochemical properties were investigated to explain the improved photovoltaic properties of the ternary blended cells.