A CsPbI3/PCBM Phototransistor with Low Dark Current by Suppressing Ion Migration

Perovskite-based metal oxide phototransistors have emerged as promising photodetection devices owing to the superior optoelectronic properties of perovskite materials and the high carrier mobility of metal oxides. However, high dark current has been one major problem for this type of device. Here, we studied the dark current behaviors of phototransistors fabricated based on the Indium Gallium Zinc Oxide (IGZO) channel and different perovskite materials. We found that depositing organic–inorganic hybrid perovskites materials (MAPbI3/FAPbI3/FA0.2MA0.8PbI3) on top of IGZO transistor can increase dark current from ~10−6 mA to 1~10 mA. By contrast, we observed depositing an inorganic perovskite material, CsPbI3, incorporated with PCBM additive can suppress the dark current down to ~10−6 mA. Our study of ion migration reveals that ion migration is pronounced in organic–inorganic perovskite films but is suppressed in CsPbI3, particularly in CsPbI3 mixed with PCBM additive. This study shows that ion migration suppression by the exclusion of organic halide and the incorporation of PCBM additive can benefit low dark current in perovskite phototransistors.