Organic-inorganic hybrid multilayer thin films were fabricated by a layer-by-layer self-assembly method at room temperature and the surface morphologies, thicknesses, surface roughnesses and optical properties of multilayer thin films were measured. The high refractive index multilayer thin films were assembled using poly (diallyldimethylammonium chloride) (PDDA) and titanium (IV) bis (ammonium lactato) dihydroxide (TALH). TiO2 crystallites ca. 5 nm in particle size were formed in the (PDDA/TALH) thin film by sequentially depositing PDDA and TALH solutions. The (PDDA/TALH)20 multilayer thin films showed a high refractive index (n = ca. 1.81) and low surface roughness (RMS = ca. 4.5 nm). The (PDDA/PSS)20 multilayer thin films with a low refractive index were assembled using poly (diallyldimethylammonium chloride) (PDDA) and poly (sodium 4-styrenesulfonate) (PSS). The refractive index of (PDDA/PSS)20 organic layers was n = ca. 1.55 at 632 nm and the surface roughness was RMS = ca. 3.4 nm. In addition, these (PDDA/TALH) and (PDDA/PSS) multilayer thin films showed a high transmittance in visible range.

Keywords: Layer-by-layer self assembly, Polyelectrolyte, TiO2, refractive index.