Graphene Oxide as Efficient Hole Transporting Material for High-Performance Perovskite Solar Cells with Enhanced Stability
In recently developed high effcieincy metal organometal halide perovskite solar cells, both the electron and hole interlayer materials have been shown palying key roles in determining the perovksite crystal growth, devie performance and stability. However, interlayer materials which can facilitate both high efficiency and stability with low-cost are still limited. Here, we demonstrate that by contolling the thickness of solution-processed graphene oxide (GO), one can achive a balance of high work-function and conductivity. Using the optmized GO as hole transporting material (HTM) in perovskite solar cells, a high PCE of 16.5% with no hysteresis can be achieved with excellent light-soaking photocurrent stability in comparison to the commonly used organic-based HTM. Under high humidity and continuous light soaking, the encapsulated perovskite devices retain over 80% of their initial efficiency for over 2,000 hours. Detailed studies on the GO binding energy and the charge transfer efficiency with perovskite, the crystal morphology have shed light on the origin of the improvement in photovoltaic devices. Benefited from the merits of low-temperature, solution-processability and low-cost, GO and the proposed fabrication techniques pave a way towards the potential scalable production of perovskite solar cells with high PCE and excellent stability.