Interfacial electronic structures of MoOx/mixed perovskite photodetector

Abstract

Abstract A systematical investigation on the electronic structures of the interface of MoOx/mixed organic cations perovskite (FA0.4MA0.6PbI3) was carried out with ultraviolet photoemission spectroscopy (UPS), X-ray photoemission spectroscopy (XPS), photoluminescence (PL) and absorption spectra (ABS). It is found that the pristine FA0.4MA0.6PbI3 film behaves as heavy n-type semiconductor. Some weakly chemical interactions are detected at the interface of MoOx/FA0.4MA0.6PbI3 from the evolution of the ratio of Mo5+/Mo6+ and attenuation of I. The results of the energy level alignment indicate a total band bending-up (shift to low binding energy) of 0.68 eV and 0.2 eV in the FA0.4MA0.6PbI3 and the MoOx layer, respectively, with the deposition of up to 128 A MoOx. The built-in field in FA0.4MA0.6PbI3 induces a strong accumulation of photogenerated holes at the interface region, which facilitates the growth of a conducting channel when the interface is used for photodetectors. A low applied voltage ∼0.8 V can overcome the interfacial potential barrier and generate continuous photocurrents based on this conducting channel in the MoOx/FA0.4MA0.6PbI3-based photodetectors. The analyses are supported by the Au/MoOx(5 nm)/FA0.4MA0.6PbI3 prototype photodetector, which obtains high performances with a detectivity of up to 2.34 × 1012 Jones and a responsivity of 0.356 A W−1, 2 times higher than the Au/FA0.4MA0.6PbI3 photodetector. Meanwhile the optimized photodector has high repeatability and stability.