Tunable UV response and high performance of zinc stannate nanoparticle film photodetectors

Abstract

High-performance photodetectors are costly due to either the expensive nature of active materials or sophistication in the fabrication process required to meet performance targets. In this work, low-cost metal stannate based nanostructures are demonstrated as active materials for high-performance UV photodetectors. A robust, inexpensive, and scalable drop-casting process was successfully developed to fabricate thin film devices composed of amorphous ZnSnO₃ nanocubes and/or polycrystalline Zn₂SnO₄–SnO₂ nanoparticles with different optical and electronic structures. Moreover, the Zn₂SnO₄–SnO₂ heterojunction nanoparticles were directly obtained by thermal treatment of amorphous ZnSnO₃ nanocubes. Large-area, uniform, and continuous film photodetectors were achieved with pronounced and fast response upon exposure to UV illumination (λ < 370 nm), showing both rise and decay times less than 1.0 s. More advantages based on these two stannate nanostructures were observed compared with their counterparts, such as ZnO, SnO₂, Zn₂SnO₄, ZnO–SnO₂ individual nanostructures or film photosensors, including high photo-sensitivities (S > 10² and ∼10³ was achieved for ZnSnO₃ and Zn₂SnO₄–SnO₂ photodetectors, respectively) and excellent responsivity (as high as 0.5 A W⁻¹ at 5.0 V bias from the Zn₂SnO₄–SnO₂ photosensors) under low light intensity. This work provides a simple, cost-effective and tunable processing strategy to synthesize and apply earth-abundant metal stannate based nanomaterials for high performance UV photodetectors and other optoelectronic devices.