Photocurrent conversion capability of a 2D WS2-polyvinyl alcohol matrix and its DFT-based charge carrier dynamics analysis

Abstract

In the present research article, we have studied the photodetection mechanism of WS₂ nanosheets embedded in a polyvinyl alcohol matrix. Hydrothermally synthesized nanosheets of WS₂ were embedded in a polyvinyl alcohol (PVOH) matrix by the solution method. The SEM micrographs show the clear incorporation of WS₂ nanosheets in the PVOH matrix. XRD results reveal the hexagonal-type crystal structure of the WS₂ nanosheets with the space group of P63/mmc. A Tauc plot of the UV-Visible absorption spectrum of the WS₂ PVOH matrix shows the optical band gap energy of 3.51 eV, which is intermediate between those of the WS₂ nanosheets and PVOH matrix. The zeta potentials of the WS₂ nanosheets, PVOH and WS₂ PVOH were found to be −10.60 mV, −4.14 mV and −1.12 mV, respectively. The responsivity and detectivity were found to be 369.13 mA W⁻¹ and 5.25 × 10¹¹ Jones, respectively, in the photodetection measurement for the WS₂ PVOH metallopolymer. The density functional studies show that upon the incorporation of the WS₂ nanosheets into the PVOH matrix, the HOMO–LUMO energy gap significantly decreases. Electronic properties such as electron affinity, ionization potential, chemical hardness, and amount of charge transfer concluded based on DFT also support the experimental results.