Van der Waals WS₂/PdSe₂ heterostructure as a visible-light photodetector and pressure optoelectronic sensor

Abstract Two-dimensional van der Waals heterostructures offer a versatile platform for developing multifunctional optoelectronic devices, as their tuneable electronic and optical properties enable a wide range of applications. Among them, WS 2 /PdSe 2 heterostructures exhibit attractive features, making them promising candidates for the realisation of broadband photodetectors and pressure optoelectronic sensors. In this study, WS 2 /PdSe 2 heterostructures were fabricated and electrically characterised under different environmental and light conditions. WS 2 /PdSe 2 heterostructures exhibit n-type conduction with an impressive ON/OFF current ratio up to 10 8 , demonstrating their suitability for high-performance electronic devices. Their electrical properties were extensively investigated under different pressure conditions, from ambient pressure to high vacuum (10 3 –10 −4 mbar), both in the dark and under illumination. The results reveal that the adsorption and desorption of water and oxygen molecules on the materials’ surface play a crucial role in modulating the electrical response of the WS 2 /PdSe 2 heterostructure. Analysis of the light response in the visible spectrum reveals a responsivity of up to 1.2 A W −1 at a wavelength of 620 nm. WS 2 /PdSe 2 -based devices were further tested as pressure optoelectronic sensors, monitoring the photocurrent evolution during transitions between high vacuum and ambient pressure. These findings open the way for various applications in the field of optoelectronics and sensing.