title: Perovskite/Poly(3-hexylthiophene)/Graphene Multiheterojunction Phototransistors with Ultrahigh Gain in Broadband Wavelength Region.
abstract: Organometal halide perovskite materials have attracted much attention recently for their excellent optoelectronic properties. Here, we report an ultrasensitive phototransistor based on the multiheterojunction of CH3NH3PbI3-xClxperovskite/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 ∼4.3 × 109A/W and a gain approaching 1010electrons 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.
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong, China.
authors.forename: Chao
authors.identifier: http://orcid.org/0000-0003-4451-767X
authors.initials: C
authors.lastname: Xie
authors.affiliation: Department of Applied Physics, The Hong Kong Polytechnic University , Hong Kong, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Yan
keywords: graphene; hole transport layer; perovskite; phototransistor; responsivity