Hazy Al₂O₃-FTO Nanocomposites: A Comparative Study with FTO-Based Nanocomposites Integrating ZnO and S:TiO₂ Nanostructures

In this study, we report the use of Al₂O₃ nanoparticles in combination with fluorine doped tin oxide (F:SnO₂, aka FTO) thin films to form hazy Al₂O₃-FTO nanocomposites. In comparison to previously reported FTO-based nanocomposites integrating ZnO and sulfur doped TiO₂ (S:TiO₂) nanoparticles (i.e., ZnO-FTO and S:TiO₂-FTO nanocomposites), the newly developed Al₂O₃-FTO nanocomposites show medium haze factor HT of about 30%, while they exhibit the least loss in total transmittance Ttot. In addition, Al₂O₃-FTO nanocomposites present a low fraction of large-sized nanoparticle agglomerates with equivalent radius req > 1 μm; effectively 90% of the nanoparticle agglomerates show req < 750 nm. The smaller feature size in Al₂O₃-FTO nanocomposites, as compared to ZnO-FTO and S:TiO₂-FTO nanocomposites, makes them more suitable for applications that are sensitive to roughness and large-sized features. With the help of a simple optical model developed in this work, we have simulated the optical scattering by a single nanoparticle agglomerate characterized by bottom radius r₀, top radius r₁, and height h. It is found that r₀ is the main factor affecting the HT(λ), which indicates that the haze factor of Al₂O₃-FTO and related FTO nanocomposites is mainly determined by the total surface coverage of all the nanoparticle agglomerates present.