Polystyrene (PS) spheres monolayers were grown by a slow evaporation selfassembly process on ALD TiO2-coated (1200 cycles at 85 ºC growth temperature) Si wafer substrates. Before the deposition, the TiO2-coated Si substrates were cleaned in a UV-ozone cleaner for 30 min for the purpose of increasing the hydrophilicity of the surface. Each PS monolayer template was prepared by placing a TiO2-coated Si substrate into a 20mL high-density polyethylene (HDPE) scintillation vial filled with 5mL of the colloidal suspension. The slow evaporation of the water from the suspension was carried out in a closed incubator at 50.0 ºC. The evaporation process driving the PS monolayer deposition took approximately 72 hours. These substrates were used for ALD TiO2 deposition without further treatment.