Optical Enhancement of Indirect Bandgap Two-Dimensional Transition Metal Dichalcogenides for Multi-Functional Optoelectronic Sensors.

The outstanding electrical and optical properties of two-dimensional (2D) transition metal dichalcogenides (TMDs) make them attractive nanomaterials for optoelectronic applications, especially optical sensors. However, the optical characteristics of these materials are dependent on the number of layers. Monolayer TMDs have a direct bandgap that provides higher photoresponsivity compared to multilayer TMDs with an indirect bandgap. Nevertheless, multilayer TMDs are more appropriate for various photodetection applications due to their high carrier density, broad spectral response from ultraviolet to near-infrared, and ease of large-scale synthesis. Therefore, this review focuses on the modification of the optical properties of devices based on indirect bandgap TMDs and their emerging applications. Several successful developments in optical devices are examined, including band structure engineering, device structure optimization, and heterostructures. Furthermore, it introduces cutting-edge optical applications based on TMDs devices. Finally, future directions in the engineering of 2D TMDs for optoelectronics are discussed. This article is protected by copyright. All rights reserved.