Self-cleaning properties of sol-gel spin-coated In2O3 thin films with varying molarity

Abstract

Indium oxide (In₂O₃) thin films were synthesized using the sol-gel spin-coating method with precursor concentrations of 0.15 M, 0.25 M, and 0.55 M, tailored for self-cleaning applications. The UV–Vis absorption spectra showed a strong absorption edge around 300 nm, with absorption intensity increasing from 0.15 M to 0.25 M and then slightly decreasing at 0.55 M. This indicates that 0.25 M film offers better light absorption. Wettability analysis revealed a decrease in water contact angle with increasing molarity: 60.2°, 41.6°and 27.1° for 0.15 M, 0.25 M and 0.55 M, respectively. Upon UV illumination, the contact angle further decreased to 42.2°, 31.3°and 23.1° confirming photo-induced hydrophilicity. This trend suggests that higher molarity films promote better water spreading, which is beneficial for self-cleaning applications. These characteristics establish In₂O₃ thin films as promising materials for water-based self-cleaning applications, demonstrating their potential in environmental remediation and surface maintenance technologies.