“…The stability of the device is largely controlled by the degradation of the active layer morphology. [55][56][57][58][59][60] Based on the intriguing relationship between T CC and phase separation, we selected PTB7-Th and PffBT4T-2OD as two model cases due to their different degrees of crystallinity. As aforementioned, these two polymers blended with ITIC have shown different T CC values (225 C for PTB7-Th and 172 C for PffBT4T-2OD) inversely related to their degree of crystallinity, as indicated in Fig- ure 2A.…”