Morphological Stabilization by Supramolecular Perfluorophenyl‐C 60 Interactions Leading to Efficient and Thermally Stable Organic Photovoltaics

A new PC 61 BM‐based fullerene, [6,6]‐phenyl‐C 61 butyric acid pentafluorophenyl ester (PC 61 BP F ) is designed and synthesized. This new n‐type material can replace PC 61 BM to form a P3HT:PC 61 BP F binary blend or serve as an additive to form a P3HT:PC 61 BM:PC 61 BP F ternary blend. Supramolecular attraction between the pentafluorophenyl group of PC 61 BP F and the C 60 cores of PC 61 BP F /PC 61 BM can effectively suppress the PC 61 BP F /PC 61 BM materials from severe aggregation. By doping only 8.3 wt% PC 61 BP F , device PC 61 BP F 651 exhibits a PCE of 3.88% and decreases slightly to 3.68% after heating for 25 h, preserving 95% of its original value. When PC 61 BP with non‐fluorinated phenyl group is used to substitute PC 61 BP F , the stabilizing ability disappears completely. The efficiencies of PC 61 BP651 and PC 61 BP321 devices significantly decay to 0.44% and 0.11%, respectively, after 25 h isothermal heating. Most significantly, this strategy is demonstrated to be effective for a blend system incorporating a low band‐gap polymer. By adding only 10 wt% PC 61 BP F , the PDTBCDTB: PC 71 BM‐based device exhibits thermally stable morphology and device characteristics. These findings demonstrate that smart utilization of supramolecular interactions is an effective and practical strategy to control morphological evolution.