All‐Oxide Transparent Photodetector Array for Ultrafast Response through Self‐Powered Excitonic Photovoltage Operation

Abstract Can photodetectors be transparent and operate in self‐powered mode? Is it possible to achieve invisible electronics, independent of the external power supply system, for on‐site applications? Here, a ZnO/NiO heterojunction‐based high‐functional transparent ultraviolet (UV) photodetector operating in the self‐powered photovoltaic mode with outstanding responsivity and detectivity values of 6.9 A W −1 and 8.0 × 10 12 Jones, respectively, is reported. The highest I UV / I dark value of 8.9 × 10 4 is attained at a wavelength of 385 nm, together with a very small dark current value of 9.15 × 10 −12 A. A large‐scale sputtering method is adopted to deposit the heterostructure of n‐ZnO and p‐NiO sequentially. This deposition instinctively forms an abrupt junction, resulting in a high‐quality heterojunction device. Moreover, developing a ZnO/NiO‐heterojunction–based 4 × 5 matrix array with an output photovoltage of 4.5 V is preferred for integrating photodetectors into sensing and imaging systems. This transparent UV photodetector exhibits the fastest photo‐response time (83 ns) reported for array configurations, which is achieved using an exciton‐induced photovoltage based on a neutral donor–bound exciton. Overall, this study provides a simple method for achieving a high‐performance large‐scale transparent UV photodetector with a self‐powered array configuration.