Hydrothermal Synthesis and Characterization of WSe₂ Nanosheets: A Promising Approach for Wearable Photodetector...

The two-dimensional (2D) WSe₂ nanostructure was successfully synthesized via the hydrothermal method and subjected to comprehensive characterization using various spectroscopic techniques. X-ray diffraction (XRD) analysis confirmed the formation of nanosheets with a hexagonal crystal structure having a space symmetry of P63/mmc. Scanning electron microscopy (SEM) images showed irregular and nonuniform morphology. The size of the 2D nanosheets was determined using transmission electron microscopy (TEM) providing insights intotheir physical characteristics. The optical spectrum analysis yielded a discernible band gap value of 2.1 eV, as determined by the Tauc equation. Photoluminescence (PL) spectra display an emission at a wavelength of 610 nm, showing a broad emission associated with self-trapped excitons. Under excitation at λ_exc = 360 nm, PL emission spectra displayed a distinct peak at 610 nm, demonstrating the ability of the nanostructure to emit vivid red light. Photometric analysis underscored the potential of this nanostructure as a prominent red-light source for diverse display applications. The optimized photodetection performance of a device showcases a photoresponsivity of approximately 1.25 × 10^-3 AW^-1 and a detectivity of around 5.19 × 10⁸ Jones at a wavelength of 390 nm. Additionally, the quantum efficiency is reported to be approximately 6.99 × 10^-3 at a wavelength of 635 nm. These findings highlight the capability of the device for efficient photoconversion at specified wavelengths, indicating potential applications in sensing, imaging, and optical communication. The combination of structural, morphological, and optical characterizations highlights the suitability of 2D WSe₂ nanostructure for practical optoelectronic applications, particularly in display technologies.