2D Transition Metal Dichalcogenide Heterostructures for p- and n-Type Photovoltaic Self-Powered Gas Sensor

2D transition metal dichalcogenides (TMDs) have attracted much attention for their gas sensing applications due to their superior responsivity at typical room temperature. However, low power consumption and reliable selectivity are the two main requirements for gas sensors to be applicable in future electronic devices. Herein, a p-type (WSe₂/WS₂) and n-type (MoS₂/WSe₂) photovoltaic self-powered gas sensor is demonstrated using 2D TMD heterostructures for the first time. The gas sensors are operated by the photovoltaic effect of 2D TMD heterostructures, which are uniformly synthesized by the vacuum-based synthesis. The gas sensing properties of the WSe₂/WS₂ and MoS₂/WSe₂ heterostructure gas sensors are investigated for NO₂ and NH₃ with changing gas concentration, and each sensor exhibits selectivity to NO₂ and NH₃. From the results, it is confirmed that the 2D TMD heterostructures can be a viable platform for highly sensitive, selective gas sensor applications without external bias due to their photovoltaic features. Further, this study contributes toward revealing the gas sensor mechanism in 2D TMD heterostructure.