ELECTRODEPOSITION AND CHARACTERIZATION OF MN DOPED COBALT OXIDE NANOSTRUCTURE THIN FILM FOR OPTOELECTRONICS

Cobalt (Co)-doped manganese oxide (MnO₂) thin films were synthesized through an electrochemical electrodeposition technique and examined for their structural and optical behavior. Deposition was carried out on FTO/glass substrates in a three-electrode configuration at 2.2 V versus Ag/AgCl, followed by annealing at 250 °C to stabilize the films. The growth pathway involved Mn²⁺ oxidation and subsequent incorporation of Co²⁺ ions into the MnO₂ lattice. Energy-Dispersive X-ray (EDX) spectroscopy confirmed the elemental composition of Mn, Co, and O in the films with no secondary impurity phases, indicating successful doping and good phase purity. Optical properties were investigated using UV–Vis spectrophotometry. The undoped films showed ~70% transmittance in the visible region, while Co-doped samples exhibited ~50% transmittance due to defect-induced scattering and enhanced photon absorption. Both doped and undoped films displayed negligible transmittance in the UV region, signifying strong absorption of high-energy photons desirable for optoelectronic and photocatalytic functions. Absorption spectra revealed a blue shift in the absorption edge from 480 nm forundoped filmsto 450 nm for doped ones, attributed to lattice distortion and electronic structure modification. Tauc plot analysis further showed a slight narrowing of the optical band gap from 2.8 eV (undoped) to 2.7 eV (doped), consistent with the creation of impurity states near the conduction band. These findings highlight that Mn incorporation effectively tailors the optical response of Co-oxide films, enhancing absorption and tuning band gap energy for potential applications in optoelectronics, photocatalysis, and solar energy conversion.