A review of recent advances in ZnO-based thin film photodetectors: Preparation, structure and strategies for performance enhancement

Ultraviolet (UV) photodetectors (PDs) serve as pivotal components in optoelectronic systems, enabling critical functionalities in environmental monitoring, optical communication, and defense technologies. Zinc Oxide (ZnO), known for its wide bandgap (3.37 eV), high exciton binding energy (60 meV), and compatibility with scalable fabrication techniques, has emerged as a possible candidate for UV detection. The ZnO thin film detector mainly has the advantages of simple preparation, good consistency, suitability for various substrates, etc. However, it still faces the disadvantage of slow response speed of ZnO itself. To obtain the solution to this problem, this review studies the photodetectors based on ZnO thin films in recent years and analyzes the methods to improve the photoelectric performance and accelerate the response speed, mainly divided into five structures: interface modification of ZnO nanoparticles (NPs), elemental doping of ZnO NPs, interlayer of ZnO film, above-surface modification and heterojunctions of ZnO film, and bottom-surface modification of ZnO film. Furthermore, this paper points out the future development directions of ZnO-based thin film photodetectors from four aspects: deep ultraviolet, wide spectrum, flexibility, and self-powered, aiming to provide strategies for the performance optimization and future applications of photodetectors.