Flexible, stable and indium-free perovskite solar cells using solution-processed transparent graphene electrodes

With the dramatic advances in performance of perovskite solar cells (PSCs) in the recent years, the flexible PSCs have triggered huge attention to distributed generation. Due to the fragility of traditional indium-based transparent electrodes, the alternatives such as graphene have been widely investigated and used in the flexible devices. However, the lack of a solution-processed method to prepare large-area and low-cost graphene electrode limits the future production via the roll-to-roll process. Here, with the assistance of ethyl cellulose, we demonstrate a highly dispersed graphene composite transparent electrode which satisfies the demand of conductivity and transmittance for flexible PSCs. Moreover, the excellent mechanical flexibility and diffusive transmittance of the graphene electrode show a great improvement in flexible PSCs, resulting in a best efficiency of 15.71%. With this strategy, the solution-processed G:EC could greatly reduce the cost of electrode in wearable and foldable electronics. The G:EC shows promising possibility to replace the indium-based transparent electrodes in the future.