Ambient-Air-Processed Ambipolar Perovskite Phototransistor With High Photodetectivity

We report an ambipolar phototransistor using the organic–inorganic hybrid perovskite, CH3NH3PbI3 [methylammonium lead iodide (MAPbI3)]. The high iconicity of MAPbI3 leads to intrinsic p-type and n-type self-doping, which enables simultaneous or selective hole and/or electron transport in a single device, depending on the bias conditions. Under white light illumination, both hole and electron current increase by four orders of magnitude and the dark characteristics recover completely and immediately after turning off the light source. In addition, the photosensitivity can be controlled by compositional ratio (MAI:PbI2) and the thickness of the MAPbI3 film. Moreover, the hole current shows higher responsivity and shorter response time (0.62 A/W and 100 ms) compared with electron current (0.20 A/W and 200 ms), resulting in respective photodetectivity values of $6.87\times 10^{15}$ and $1.33\times 10^{15}$ Jones. These photodetectivities are among the highest reported, making the phototransistors reported herein suitable for simple and cost-effective optoelectronics.