Fabrication of WO₂I₂/poly o-amino thiophenol porous spherical-nanocomposite with promising optical absorbance for photodetector device applications

This study focuses on the fabrication of WO₂I₂/poly o-amino-thiophenol porous spherical-nanocomposite (WO₂I₂/POATP PS-nanocomposite) with promising optical absorbance for photodetector applications. The PS-nanocomposite is synthesized through the oxidation of o-amino-thiophenol using iodine, followed by a reaction with Na₂WO₄. The resulting nanocomposite exhibits wide optical absorbance extending into the IR region and a small bandgap of 2.0 eV. The spherical particles have pores with a diameter of 5 nm, and their crystalline peaks demonstrate excellent crystallinity with a crystal size of 121 nm. This combination of crystalline behavior, morphology, and optical absorbance suggests that the WO₂I₂/POATP PS-nanocomposite is a highly sensitive photodetector suitable for a broad optical spectrum, including UV, visible, and IR regions. The device’s application in photon sensing is evaluated by measuring the photocurrent using linear sweep voltammetry, determining the current density (Jph) under light and dark conditions (Jo). The Jph and Jo values are found to be 0.8 and 0.48 mA/cm², respectively, resulting in a photocurrent of 0.32 mA/cm², a promising value that indicates significant photon sensitivity. The photoresponsivity (R) is assessed based on the impact of photon energies on the Jph values, with R values increasing from 7.2 to 8.0 mA/W as the wavelength decreases from 540 to 340 nm. Similarly, the detectivity (D) value increases from 0.164 × 10¹⁰ to 0.181 × 10¹⁰ Jones over the same wavelength range. At 730 nm, both R and D maintain substantial values of 6.4 mA/W and 0.145 × 10¹⁰ Jones, respectively. This fabricated optoelectronic device, with its excellent sensitivity, stability, reproducibility, low cost, and potential for mass production, holds significant promise for industrial applications as a highly effective photodetector.