Structural and Optical Modifications of Indium‐Doped Copper Oxide (CuO) Thin Films Synthesized by Chemical Bath Deposition for Enhanced Photoluminescence

Indium (In)‐doped copper oxide (CuO) thin films were successfully synthesized on glass substrates using a simple one‐step chemical bath deposition (CBD) technique. The effect of In‐doped CuO thin film on the structural, morphological, and optical characteristics was investigated to enhance its potential photoluminescence (PL) properties. Based on the x‐ray diffraction (XRD) data, crystallite sizes were quantitatively assessed using the Scherrer formula and the Williamson–Hall (W‐H) approach. Optical measurements demonstrated a tunable bandgap, decreasing from 2.35 eV in undoped films to 1.90 eV at 0.3 M doping, enhanced UV–Vis light absorption, and improved PL, particularly at moderate doping levels. This bandgap narrowing indicates an improved ability to absorb visible light, enhancing the material's suitability for photovoltaic applications. Fourier‐transform infrared (FTIR) spectroscopy exhibited distinct alterations in the vibrational modes associated with hydroxyl groups, C–O bonds, and Cu–O linkages, indicating modifications in surface chemistry and bonding configurations due to In doping. PL analysis showed a dominant green emission centered at 525 nm for the 0.3 M In‐doped sample, attributed to changes in recombination mechanisms. This study highlights that controlled In doping can significantly tailor the structural, optical, and morphological properties of CuO thin films, making them promising candidates for applications in PL, photocatalysis, and solar cell systems.