Enhanced Detectivity and Suppressed Dark Current of Perovskite–InGaZnO Phototransistor via a PCBM Interlayer

Hybrid phototransistors based on InGaZnO (IGZO) metal oxide thin-film transistors (TFT) and a photoabsorbing capping layer such as perovskite (MAPbI3) are a promising low-cost device for developing advanced X-ray and UV flat-panel imagers. However, it is found that the introduction of MAPbI3 inevitably damages the IGZO channel layer during fabrication, leading to deteriorated TFT characteristics such as off-current rising and threshold voltage shift. Here, we report an effective approach for improving the performance of the perovskite–IGZO phototransistor by inserting a [6,6]-phenyl C61-butyric acid methyl ester (PCBM) or PCBM:PMMA interlayer between the patterned MAPbI3 and IGZO. The interlayer effectively prevents the IGZO from damage by the perovskite fabrication process, while allowing efficient charge transfer for photosensing. In this configuration, we have achieved a high-detectivity (1.35 × 1012 Jones) perovskite–IGZO phototransistor with suppressed off-state drain current (∼10 pA) in the dark. This work points out the importance of interface engineering for realizing higher performance and reliable heterogeneous phototransistors.