Sponge-templated production of ultra-thin ZnO nanosheets for printed ultraviolet photodetectors

Abstract

This paper describes a simple and convenient approach to synthesize large amounts of ZnO nanosheets, which are suitable for producing a key component, i.e., colloidal nanoink, of printed ultraviolet photodetectors. ZnO nanosheets are produced by atomic layer deposition, where a three-dimensional polymer sponge with a large specific surface area is used as the template. Systematic studies including scanning electron microscopy, X-ray diffraction, and transmission electron microscopy reveal that the synthesized ZnO nanosheets have a good crystalline quality and mechanical flexibility. After dispersing ZnO nanosheets in a solvent to form a stable and colloidal nanoink, an ultraviolet photodetector is demonstrated through the printing method. Such a printed ultraviolet photodetector that utilizes ZnO nanosheets as the functional materials exhibits a high responsivity of ∼148 A/W and a response time of 19 s. Our present study may provide a practical method to produce large amounts of functional nanosheets for printing electronics, which paves the way for developing high-performance, low-cost, large-area printed, and flexible electronics.