Transparent photodetectors based on polyoxometalate modified electrospun ZnO homojunction nanowire intersection arrays

Abstract

Transparent photodetectors (PDs) based on binary metal oxides have become a hot topic in the field of photodetection because of their ability to absorb and detect ultraviolet (UV) light. However, PDs constructed with pure binary metal oxides still have the problems of slow response time and high-voltage drive. In addition, due to its natural internal defects, it has the characteristics of an n-type semiconductor and is difficult to achieve p-type conversion. In this work, the top layer of the device is polyoxometalate (POM) modified ZnO NWs which showed the characteristics of p-type semiconductors, its UV absorption was increased by 36.9%, and the bottom layer of the PD is pure ZnO NWs. An interlayer p–n junction is formed between the two layers, which is not only conducive to carrier transmission, but also can complete photodetection without bias. The PD has a transparency of more than 70% in the visible light region. Under the conditions of zero bias and AM 1.5 illumination, the light–dark current difference (ΔI) reaches 23.76 μA, and the rise-fall time is 1.32 s/2.62 s, respectively. After 216 hours of cycling, it still maintains 70% of the original efficiency.