Synthesis of C-60-end capped P3HT and its application for high performance of P3HT/PCBM bulk heterojunction solar cells

A new C-60-end capped poly(3-hexylthiophene) (P3HT-C-60) was synthesized via a simple three-step process, and used as a compatibilizer for P3HT/PCBM composite for the purpose of controlling the morphology of P3HT/PCBM composite film, and thus improving the long-term thermal stability of solar cell performance. When a small amount of P3HT-C-60 was added to P3HT/PCBM, the bicontinuous and nanometre-scale film morphology was developed and preserved for 2 h of annealing at 150 degrees C. Furthermore, the addition of P3HT-C-60 as a compatibilizer suppressed large-scale phase separation of P3HT/PCBM composite even after prolonged annealing time (8 days), and as a result, the P3HT/PCBM/P3HT-C-60 bulk heterojunction solar cells exhibited the excellent long-term thermal stability of device performance.