Lanthanum element enhances the UV resistance and anti-reflection properties of sol–gel prepared SiO₂ films

To address the susceptibility of porous Silica (SiO₂) antireflection coatings to ultraviolet (UV) degradation, this study introduces a dual-functional strategy incorporating methoxy polyethylene glycol (mPEG) as a porogen and lanthanum nitrate (La(NO₃)₃) as a UV-blocking agent via a sol–gel approach. Systematic investigations revealed that La(NO₃)₃ incorporation synergistically optimizes film architecture and spectral performance. Notably, the average transmittance of optimized films (0.3 wt% La 3 ⁺) in the 400–1100 nm range reached 93.1%, exhibiting a 4.57 percentage point enhancement compared to blank glass substrates (T ave  = 88.5%). Mechanical characterization confirmed robustness, with a pencil hardness of 9 H and adhesive strength exceeding industry standards (tape-tearing grade 0). Furthermore, accelerated aging tests (5000 equivalent solar hours, ESHs) demonstrated superior photostability: while pristine films suffered a 1.22 percentage point transmittance loss, La 3+ -doped films retained 92.25% transmittance with minimal degradation (0.85 percentage point). Notably, the pencil hardness only decreased by 1 H (from 9 to 8 H) while maintaining a tape-tearing adhesion grade of 0. The enhanced UV resistance arises from La 3 ⁺-induced surface passivation and UV photon scattering in the short-wavelength regime, effectively mitigating photooxidative damage. This work advances the development of durable, transparent UV-blocking coatings for optoelectronic and architectural applications.