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Two-dimensional (2D) tungsten disulfide nanosheets (WS2) could be a promising candidate for high-performance self-powered photodetectors. The present 2D nanosheets were obtained from liquid exfoliation in a mixture of ethanol, methanol, and isopropanol via a direct dispersion and ultrasonication method. Using the spin-coating technique, a thin film of uniform thickness was formed on the SiO2/Si substrate. Energy-dispersive X-ray analysis showed that the S/W ratio in the fabricated WS2 film was around 1.2 to 1.34, indicating certain deficiencies in the S atoms. These S vacancies induce localized states within the bandgap of pristine WS2, resulting in a higher conductivity in the exfoliated sample. The obtained thin film seems to be highly efficient in photoelectric conversion, with a responsivity of ~0.12 mA/W at 670 nm under zero bias voltage, with an intensity of 5.2 mW/cm2. Instead, at a bias of 2 V, it exhibits a responsivity of 12.74 mA/W and a detectivity of 1.17 × 1010 cm Hz1/2 W− 1 at 4.1 mW/cm2. The present 2D nanosheets exhibit high photon absorption in a wide range of spectra from the near infrared (IR) to near UV spectrum. 

This study presents a fast and effective method to synthesize 2D boron nitride/tungsten nitride (BN–WN) nanocomposites for tunable bandgap structures and devices. A few minutes of synthesis yielded a large quantity of high-quality 2D nanocomposites, with which a simple, low-cost deep UV photo-detector (DUV-PD) was fabricated and tested. The new device was demonstrated to have very good performance. High responsivity up to 1.17 A/W, fast response-time of lower than two milliseconds and highly stable repeatability were obtained. Furthermore, the influences of operating temperature and applied bias voltage on the properties of DUV-PD as well as its band structure shift were investigated.