Influence of Sn doping on structural, optical, and photoelectrical properties of NiO nanostructures for optoelectronic applications

This work presents the synthesis of Sn doped NiO nanostructures with varying doping concentrations (0%, 1.25%, 2.5%, 5%, and 10%) using a hydrothermal method, aiming to explore the impact of Sn incorporation on their structural, optical, and photoelectrical behavior. X-ray diffraction (XRD) patterns confirmed the retention of the face-centered cubic phase across all samples, with a notable reduction in crystallite size from 16.02 nm (undoped) to 11.90 nm (10% Sn-doped), attributed to the partial substitution of Ni 2+ by Sn 4+ ions. Scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX) revealed a progressive decrease in particle size and improved morphological uniformity as the Sn content increased. UV–Vis spectral analysis exhibited a redshift in the absorption edge with increasing Sn concentration, corresponding to a narrowing of the optical band gap from 3.16 eV to 2.68 eV, which facilitates enhanced photon absorption. Under UV illumination, the photocurrent response improved significantly, with the 10% Sn-doped sample demonstrating a peak photocurrent of 25.09 nA at 3 V bias, compared to 16.28 nA for the pristine NiO. The highest photosensitivity and photoresponsivity were recorded for the 10% Sn-doped sample, reaching 0.16 μA/W. These results underscore the potential of Sn doping as a viable strategy to enhance the photoelectrical performance of NiO-based nanostructures for optoelectronic device applications, particularly in UV photodetection technologies.