Publication: Analysis of photocatalytic activity suppression and accelerated weathering test of silicone films with hybrid zno-tio2 for led applications
Loading...
Date
2025-08-06
Authors
Jerome, Kee Wei Jie
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
As demand for LED-based products increases, mitigating discoloration in silicone encapsulants caused by UV radiation and heat is essential. This study aims to reduce such degradation by synthesizing ZnO–TiO₂ hybrid particles via the sol-gel method, targeting suppression of TiO₂'s inherent photocatalytic activity. Key synthesis parameters including the pH of TiO₂ and ZnO sols, calcination duration, and ZnO–TiO₂ ratio were optimized to enhance performance. The best-performing hybrid formulation (TiO₂ sol pH 2, ZnO sol pH 10, 5-hour calcination) was incorporated into RTV silicone films via spin coating on polycarbonate substrates. Photocatalytic activity was evaluated using methylene blue degradation, while film durability was assessed through accelerated weathering tests measuring discoloration, surface morphology, and thickness changes. Characterization methods included UV-Vis spectroscopy, FTIR, XRD, SEM, FESEM, AFM, colorimetry, TGA, BET surface area, and zeta potential analysis. After 300 hours of UV exposure, silicone films containing the optimized hybrid particles showed the least degradation: darkening index (–0.98), yellowness index (0.61), total color difference (1.20), surface roughness increase (7.24%), and thickness reduction (11.6%). In conclusion, the incorporation of ZnO–TiO₂ hybrid particles significantly reduced photodegradation and discoloration in silicone encapsulants, improving their long-term optical and physical stability for LED applications.