High Tg Polymer Insulator Yields Organic Photovoltaic Blends with Superior Thermal Stability at 150 °C

Main observation and conclusion Record-breaking organic solar cells (OSCs) based on blends of polymer donors and small molecule acceptors often show undesirable degradation, which severely precludes their practical use. Herein, we demonstrate a facile and cost-effective approach to construct thermally stable OSCs at 150 degrees C by incorporating a small amount of a polymer insulator polyacenaphthylene (PAC) with high glass-transition temperature over 230 degrees C into polymer:acceptor blends. The model PTB7-Th:EH-IDTBR blend with 10 wt% PAC maintained above 85% of its initial efficiency upon continuous heating at 150 degrees C for over 800 h, while the efficiency of the blend without PAC sharply dropped by 70% after similar to 300 h. Owing to high miscibility with acceptors, PAC confines the motion of the acceptor molecules and suppresses the acceptor crystallization at elevated temperatures, leading to significantly improved stability. Importantly, the effectiveness of this blending approach was also validated in many other OSC systems, showing great potential for achieving high-performance thermally stable electronics.