Hybrid graphene–ZnO nanocomposites as electron acceptor in polymer-based bulk-heterojunction organic photovoltaics

Graphene–zinc oxide (G–ZnO) nanocomposites were prepared through a hydrothermal approach and used as electron acceptors in poly-(3-hexylthiophene) (P3HT)-based bulk-heterojunction organic solar cells (OSCs). The blended film, which was a mixture of different weight ratios of P3HT and G–ZnO, was applied as the active layer in the OSC device. The power conversion efficiency (PCE) increases first and then decreases with the increase in G–ZnO content in the blended films. The device containing 15 wt% (ratio to P3HT) of G–ZnO shows the best performance with a PCE of 0.98%, an open-circuit voltage of 0.81 V and a short-circuit current density of 4.92 mA cm−2. The impact of the intrinsic mechanism on the characteristics of the OSCs under the illumination condition is discussed.