Tunable Dual‐Photoconductivity in VS ₂ Films

ABSTRACT 2D semiconducting H‐phase vanadium disulfide (VS 2 ) has attracted significant research interest due to its exceptional potential in electronics, optoelectronics, spintronics, and valleytronics. In this work, VS 2 thin films are synthesized via chemical vapor deposition for the application of photodetectors, revealing a tunable dual‐photoconductivity effect induced by CO 2 adsorption and light‐assisted desorption. CO 2 adsorption led to negative photoconductivity, achieving a remarkable responsivity of ∼2680 A/W and an ultra‐high external quantum efficiency of ∼1.3 × 10 6 %. In contrast, VS 2 photodetectors free from CO 2 adsorption exhibited stable positive photoconductivity, with a maximum responsivity and external quantum efficiency of ∼0.11 A/W and ∼30.47%, respectively. First‐principles calculations demonstrate that CO 2 exhibits superior adsorption and desorption capabilities on the VS 2 surface compared to other ambient gas molecules (e.g., N 2 , O 2 , and H 2 O). This work highlights the profound influence of gas adsorption on the photoconductivity behavior of VS 2 thin films, providing critical insights into their optoelectronic properties and enabling non‐destructive modulation for advanced device applications.