High performance CsPbBr3 perovskite nanocrystal vertical phototransistor with graphene electrode

All-inorganic cesium lead halide perovskites (CsPbX3, X = Cl, Br, and I) nanocrystals (NCs) have been extensively studied as optically active materials in photodetectors, light-emitting diodes, solar cells and lasers, in view of their combination of the outstanding characteristics of perovskites and NCs such as low cost, solution processability, bandgap tunability, and large absorption coefficient. Here we report the fabrication of graphene electrode based CsPbBr3 NCs vertical field-effect phototransistor (VFEPT), exhibiting high photoelectrical performances benifiting from the ultrashort channel, the high ultraviolet–visible absorption of CsPbBr3 NCs, and the adjustable Fermi level of graphene. The VFEPT exhibited high drain current density of 0.25 A/cm2 for p-type and 0.2 A/cm2 for n-type transports in dark condition. The responsivity, effective quantum efficiency and detectivity reached as high as 2.2 × 103 A/W, 6.7 × 105%, 1.1 × 109 Jones at an irradiance power of 342 mW/cm2 under 405 nm illumination. Additionally, the device showed excellent stable and reproducible dynamic response to cyclical optical signal, with the rise and decay time as fast as 20 ms/36 ms. The device described here has great potential applications in high-sensitivity, high-speed, and low-power nanometer-scale photodetectors.