Crossiinked poiythiophene limits PCBM diffusion and phase separation

摘要

High power conversion efficiencies have been reported lately using the polymer bulk heterojunction concept of solar cells. Values of 5% have been obtained using poly(3-hexylthiophene) (P3HT) as the donor and [6,6]-phenyl C_(61)-butyric acid methyl ester (PCBM) as the acceptor material, after an appropriate thermal treatment. However, blends of these two materials have two problems: poorly controlled donor/acceptor domain size distribution and an inherent morphological instability. Consequently the domain sizes of these two incompatible components increase with time, resulting in a decreasing device performance. One reported strategy for improving long term performance is to crosslink the active layer and prevent migration of the fullerene species.