Janus 2D Transition Metal Dichalcogenides: Research Progress, Optical Mechanism and Future Prospects for Optoelectronic Devices

Exploring the extraordinary optoelectronic properties of two-dimensional (2D) materials to construct advanced optoelectronic devices is a major goal for academic researchers and industrialists. Emerging 2D Janus materials are the innovative class of 2D materials in which two sides are either asymmetrical functionalized or exposed to different environments. Distinctive features of Janus 2D materials such as tunable bandgaps, electronic structures, the presence of Rashba effects, excitonic effects, piezoelectric effects etc. make its magnificent candidates for optoelectronic devices. The van der Waals (vdWs) heterostructure with novel properties assembled by Janus 2D materials and low dimensional materials provides new opportunities and promising applications. This review aims to offer the recent advances in the Janus 2D materials and inside mechanism in 2D Janus vdWs heterostructure from an optoelectronics point of view. Here, the latest progress in the Janus 2D materials including their vdWs heterostructures from the perspective of theoretical prediction, and synthesis techniques is presented. The investigation of their physical optoelectronics properties and optoelectronic device applications is summarized. Finally, the future directions, challenges, and opportunities regarding the research process of Janus 2D materials and their vdWs heterostructure are discussed for designing promising optoelectronic devices.