Influence of Mg Concentration on Overall Performance of APTES–ZnO/PANI Hybrids Flexible UV Photodetectors

Zinc oxide (ZnO) nanoparticles combined with conducting polymers such as polyaniline (PANI) demonstrate promising potential in flexible ultraviolet (UV) photodetection applications. However, the overall performance of undoped ZnO in photodetectors is often limited by high dark current, low responsivity, and detectivity, attributable to the high density of intrinsic defects and recombination rates. This study was aimed at evaluating the influence of magnesium (Mg) concentration (0.5≤x≤3.0% mol) on the structural and optical properties of 3-aminopropyltriethoxysilane (APTES)-modified ZnO/PANI hybrid matrix for ultraviolet (UV) photodetector applications. The novelty of this work lies in the dual strategy of Mg doping and surface modification intended to tailor the optoelectronic properties of ZnO nanoparticles (NPs). X-ray diffraction analysis confirmed the formation of a single-phase wurtzite ZnO. Photoluminescence measurements revealed a significant increase in photoemission intensity with increasing Mg concentration up to a maximum 2.0% mol. Incorporation of Mg remarkably modified the surface morphology and topography of the ZnO/PANI thin film, demonstrating an increase in both surface area and roughness. The Mg-ZnO/PANI photodetector with 1.0% mol of Mg doping concentration demonstrated excellent performance, with responsivity of 2.34 × 10^-2 A/W and detectivity of 1.56 × 10¹⁰ Jones. The effect of Mg doping concentration on the photoemission and photodetection is discussed in detail.