| 초록 |
Here, we systematically design widely used all-PSCs systems consisting of PBDB-T:P(NDI2OD-T2) modulating molecular weight of P(NDI2OD-T2) from 9 to 115 Kg mol-1 to thoroughly analyze the origin of D:A ratio tolerance in all-PSCs and correlation with mechanical properties of photoactive layers. We revealed P(NDI2OD-T2) with high molecular weight (Mn = 115 kg mol-1) show 13.4 - times higher D:A ratio tolerance compared with low molecular weight polymer acceptors (Mn = 9 kg mol-1), maintaining 67% of power conversion efficiency (PCE) at 15:1 D:A ratio. This difference in chain entanglement extent by polymer chain length also directly affect to mechanical toughness of photoactive thin fims, blend films with high molecular weight acceptor maintain very high crack onset strain(COS) above 30% throughout all D:A ratio ranges, while blends with low molecular weihgt acceptor showed steeply decreased COS from 33% at 1:1 D:A ratio to 0.21% at 1:10 D:A ratio. |
