Enhancing the performance of UV-photodetector based on PAni-Co₃O₄ nanocomposites prepared by spin coating method

The spin coating method successfully prepared an p-n (PAni-Co₃O₄)/Si heterojunction core–shell UV-photodetector by depositing PAni NFs and PAni-Co₃O₄ nanocomposites films on glass and n-type silicon substrates. The structural investigations revealed that PAni has a fiber-like semicrystalline structure and polycrystalline spinal cubic phase in the form of spherical aggregated nanoparticles for Co₃O₄, and core/shell-like coaxial structures for the PAni/Co₃O₄ nanocomposites. The UV–Vis spectrum showed two peaks for PAni NFs at 296 and 627 nm. In the nanocomposites, these peaks shifted to longer wavelengths, indicating a decrease in the energy gap value. The I–V curves for the p-n PAni/Si and p-n (PAni/Co₃O₄)/Si heterojunctions showed non-linear and asymmetric behavior in the dark and when illuminated at different intensities of forward and reverse bias. We also observed an increase in the photoresponse as the illumination intensity and Co₃O₄ content in the nanocomposites increased. The C–V plot of p-n PAni/Si and p-n (PAni/Co₃O₄)/Si heterojunctions showed that the capacitance decreased as the amount of Co₃O₄ nanoparticles in the nanocomposites increased. The built-in voltage was calculated from the C⁻²–V plot linear intercept for PAni NFs and PAni/Co₃O₄ heterojunction nanocomposites. In the 300–500 nm range, UV-photodetector investigations revealed a photocurrent increasing with increasing Co₃O₄ content in heterojunction nanocomposites. The rise time and fall time of the generated photocurrent pulses were calculated within the ranges (6–7) and (8–9) seconds, respectively. As the cobalt oxide content increased, the prepared heterojunctions' detectivity and responsivity increased; this is a feature that improves the UV-photodetector's performance.