Perovskite/Poly(3-hexylthiophene)/Graphene Multiheterojunction Phototransistors with Ultrahigh Gain in Broadband Wavelength Region

Organometal halide perovskite materials have attracted much attention recently for then. excellent optoelectronic properties. Here, we report an ultrasensitive photo transistor based on the multiheterojunction of CH3NH3PbI3-xClx perovskite/poly(3-hexylthiophene)/graphene for the first time. Since the photoexcited electrons and: holes are effectively separated by the poly(3-hexylthiophene)layer, high-density electrons are trapped in the perovskite layer, leading to a strong photogating effect on the underlying graphene channel. The phototransistor demonstrates an unprecedented ultrahigh responsivity of similar to 4.3 X 10(9) A/W and a gain approaching 10(10) electrons per photon, respectively. More importantly, the device is sensitive in a broadband wavelength region from ultraviolet to near-infrared, which has not yet been achieved with other perovskite photodetectors. It is expected that the novel: perovskite phototransistor will find promising applications as photodetection and imaging devices in the future.