Adjusting the Energy Bands of WO3@ZnO Nanocomposite Heterojunction Through the Combination of WO3 Thin Film to Improve its Photoelectric Performance

Yan Xu,Pinghui Wu,Shuangshuang Cai,Qin Cao,Zao Yi

doi:10.1109/access.2020.3024827

Abstract

At present, nanomaterials with high-quality photoelectric properties are urgently needed to be used in the manufacture of solar cells. In this study, the hydrothermal synthesis method was first used to grow ZnO nanorod arrays, and then a layer of WO3 thin film with controllable thickness was prepared on ZnO nanorod arrays by magnetron sputtering, forming a series of WO3@ZnO nanocomposite heterojunction. We found that the value of the photocurrent of the prepared nanocomposite samples is nearly 30 times higher than WO3 films under illumination, and it is more stable. The results show that this controllable microstructure can further modify the surface properties of ZnO nanorods, and possess the high visible absorption and photoelectric conversion efficiency. By controlling the thickness of the WO3 film, the band can be regulated and ultimately optimized the photoelectrochemical properties of the composite structure.

Highlights

In recent years, tungsten oxide has drawn widespread attention because of its characteristic properties, just like electrochromism, gas sensitivity, photoluminescence and superconductivity [1]–[9]
Sample 1# shows that the crystal structure of ZnO nanorods corresponds to that of wurtzite ZnO and there is no impurity peak (These peaks can be well indexed to the standard diffraction pattern of wurtzite ZnO structure (PDF # 01-089-1397))
As shown in the figure, compared with the peaks of Sample 1#, the peaks belonging to ZnO in all composites haven’t moved, which means that the transition metal oxide WO3 will not replace the lattice of ZnO, and the thickness of WO3 has a trivial impact on the crystallization phases of ZnO nanorods formed previously

Summary

INTRODUCTION

Tungsten oxide has drawn widespread attention because of its characteristic properties, just like electrochromism, gas sensitivity, photoluminescence and superconductivity [1]–[9]. An appropriate substitute material for TiO2 is ZnO, which has a similar band structure and electron affinity to TiO2, and has a larger absorption ratio in the solar spectrum than TiO2 [38] It has a lot of research in the photoelectrochemical water splitting experiment [39]–[41]. Coupling ZnO with WO3 can enlarge the spectral response range, increase the utilization of visible light, change the band structure and repress the combination of electron-hole pairs, improving the performance of the material. In this experiment, loading an appropriate amount of WO3 can maximize the photo-current. For better comparison of composite samples, the samples containing only pure ZnO nanorods were annealed

CHARACTERIZATION

RESULTS AND DISCUSSIONS

CONCLUSION