Ultrathin and flexible perovskite solar cells with graphene transparent electrodes

Flexible and light weight perovskite solar cells have attracted much attention recently for their broad potential applications especially in wearable electronics. However, highly flexible devices cannot be realized with the conventional transparent electrodes based on conductive oxides since they are rigid and brittle. Here, we demonstrate the fabrication of ultrathin and flexible perovskite solar cells with graphene transparent electrodes for the first time. The flexible devices with the structure of polyethylene terephthalate/graphene/poly(3-hexylthiophene)/CH3NH3PbI3/PC71BM/Ag are prepared on 20 µm-thick polyethylene terephthalate substrates by low-temperature solution process, which show the power conversion efficiency of 11.5% and high bending durability. Moreover, the devices demonstrate the power output per weight (specific weight) of about 5 W/g, which is much higher than those of conventional inorganic solar cells. This work paves a way for preparing flexible perovskite solar cells as well as other optoelectronic devices by using graphene transparent electrodes.