▎ 摘　　要

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.