Boosting Visible Light Absorption of Metal-Oxide-Based Phototransistors via Heterogeneous In–Ga–Zn–O and CH₃NH₃PbI₃ Films

To broaden the availability and application of metal–oxide (M–O)-based optoelectronic devices, we suggest heterogeneous phototransistors composed of In–Ga–Zn–O (IGZO) and methylammonium lead iodide (CH3NH3PbI3) layers, which act as the amplifier layer (channel layer) and absorption layer, respectively. These heterogeneous phototransistors showed low persistence photocurrent compared with IGZO-only phototransistors and exhibited high photoresponsivity of 61 A/W, photosensitivity of 3.48 × 106, detectivity of 9.42 × 1010 Jones, external quantum efficiency of 154% in an optimized structure, and high photoresponsivity under water exposure via the deposition of silicon dioxide as a passivation layer. On the basis of these electrical results and various analyses, we determined that CH3NH3PbI3 could be activated as a light absorption layer, current barrier, and plasma damage blocking layer, which would serve to widen the range of applications of M–O-based optoelectronic devices with high photoresponsivity and reliability under visible light illumination.