Effect of fullerene substituent on thermal robustness in polymer:fullerene bulk heterojunction solar cells

摘要： Effect of fullerene substituent on thermal robustness in polymer:fullerene bulk heterojunction solar cells using a conjugated polymer PTB7-Th. While 175 °C is the best annealing temperature for a solar cell with unmodified C70, it deteriorates a device with a substituted C70 (C70-PCBM). Additionally, annealing at 175 °C does not change the surface of PTB7-Th:C70 film but makes the surface of PTB7-Th:C70-PCBM film bumpy. The results suggest that the substituent promotes the migration of fullerene in polymer:fullerene solid composite.