Influence of ZnO Composition on the Physical Properties of Mn_0.75Fe_2.25O₄/ZnO/PVP/PABS Nanocomposites and Their Application as Photodetector Materials

This study aims to develop an active photodetector material based on a nano composite thin film of Mn 0.75 Fe 2.25 O 4 /ZnO/PVP/PABS. This material has been successfully synthesized using a multi-method approach, including co-precipitation for Mn 0.75 Fe 2.25 O 4 , sol-gel processing for ZnO, and dual-solution polymerization to produce PABS. X-ray diffraction revealed high crystallinity, with Mn 0.75 Fe 2.25 O 4 crystallite sizes of 5.25–8.21 nm and ZnO crystallite sizes of 11.19–17.60 nm, corroborated by transmission electron microscopy (11.00–17.33 nm). VSM tests uncovered superparamagnetic behavior, with saturation magnetization ( M s ) values decreasing from 13.97 to 8.02 emu g −1 as ZnO content increased. UV–Vis spectroscopy indicated band gap energies of 3.15–3.57 eV, refractive indices of 1.87–2.13, optical conductivities of (8.50–9.68) × 10 7 S cm −1 , and electrical conductivities of 25.91–29.52 S cm −1 . Photodetector performance testing demonstrated rise times of 0.11–1.11 s and decay times of 0.99–2.53 s, reflecting a fast and stable response under visible light illumination. The novelty of the study lies in the integration of four components, including Mn 0.75 Fe 2.25 O 4 nanoparticle, ZnO semiconductor, PVP matrix polymer, and conductive PABS polymer, into an inorganic-organic hybrid nano-composite thin film fabricated via spin coating. These findings offer a cost-effective and highly applicable alternative for photodetector materials in future optical sensor technologies.