Influence of Oblique Angle Deposition on the Structural, Optical, and Photocatalytic Performance of TiO₂ Thin Films

In the present study, TiO₂ thin films were deposited on glass substrates using thermal evaporation technique at oblique angles of 40°, 60°, 70°, and 80° to study the influences of deposition angles on the structural, optical, and photocatalytic properties of the deposited films. FESEM and AFM studies showed increasing deposition angle results in a porous and rough surface morphology. This is attributed to shadowing effects and limited adatom diffusion. The optical transmittance and absorption spectra were recorded using a UV–Vis spectrophotometer, indicating that films deposited at higher oblique angles exhibited enhanced light transmission and modified absorption behavior. The photocatalytic activity of the TiO₂ thin films was evaluated through methylene orange degradation under UV irradiation. The degradation efficiency was followed in time steps of 30, 60, 90, and 120 min. The results showed that the sample deposited at 60° exhibits the maximum photocatalytic activity. This is regarded as an enhancement due to its optimized surface roughness and increased surface area, improving photon absorption and charge carrier separation.