Solvent-free fabrication of broadband WS<sub>2</sub> photodetectors on paper

Paper-based devices have attracted extensive attention due to the growing demand for disposable flexible electronics. Herein, we integrate semiconducting devices on cellulose paper substrate through a simple abrasion technique that yields high-performance photodetectors. A solvent-free WS₂ film deposited on paper favors an effective electron-hole separation and hampers recombination. The as-prepared paper-based WS₂ photodetectors exhibit a sensitive photoresponse over a wide spectral range spanning from ultraviolet (365 nm) to near-infrared (940 nm). Their responsivity value reaches up to ~270 mA W⁻¹ at 35 V under a power density of 35 mW cm⁻². A high performance photodetector was achieved by controlling the environmental exposure as the ambient oxygen molecules were found to decrease the photoresponse and stability of the WS₂ photodetector. Furthermore, we have built a spectrometer using such a paper-based WS₂ device as the photodetecting component to illustrate its potential application. The present work could promote the development of cost-effective disposable photodetection devices.