Layer-by-Layer-Processed Ternary Organic Solar Cells Using Perylene Bisimide as a Morphology-Inducing Component

A perylene bisimide (PBI-C4) with strong self-aggregation ability was used with polythieno[3,4- b ]-thiophene/benzodithiophene (PTB7) to form an underlying morphology-inducing layer in organic solar cells. The PTB7:PC 71 BM ([6,6]-phenyl C 71 butyric acid methyl ester) spin-coated atop the preprocessed morphology-inducing thin layer showed an enhanced domain size with better phase separation compared with the conventional spin-coating of PTB7:PC 71 BM on ZnO directly. Proper aggregation morphology of the active layer shows higher electrical properties resulting in a 14% improvement in the power conversion efficiency (PCE) (8.96% vs 7.85%). After replacing the ZnO cathode interlayer with a photoconductive interlayer (ZnO:PBI-H), a maximum PCE of 9.47% is obtained, which is among the best device performance based on PTB7:PC 71 BM systems.