The effects of polyvinylpyrrolidone and thermal annealing on red shifts for absorption spectra of the nanoparticle Au/TiO₂ thin film with different Au ratios

Plasmonic solar cell efficiency strongly depends on parameters of Au/TiO₂ nanoparticles (NPs) embedded system including Au sizes, distribution, aggregation, and dielectric environment—polymer encapsulated around Au/TiO₂ NPs. This paper briefly outlines the technological developments for preparation of the nanoparticles Au/TiO₂ solutions with different Au ratios, in presence of 200, 500 mg PVP and in absence of polyvinylpyrrolidone (PVP). After that from the obtained solutions, the Au/TiO₂ thin films are prepared by spin coating method aiming to get different Au nanoparticles (Au NPs) sizes with uniform dispersion. The next step, the Au/TiO₂ thin films samples have been annealed at different temperatures, the absorption spectra of the different Au/TiO₂ NPs thin films are investigated using the UV–Vis spectroscopy techniques. The obtained experiment results show that the absorption spectra in the case of not thermal annealing is blue shift meanwhile in the case of thermal annealing, the absorption spectra are red shifted, enhanced depending on the annealing temperatures, Au sizes, ratios and PVP amounts. The enhancement and red shifts of absorption spectra for each case of Au/TiO₂ NPs thin films have been discussed and explained by interaction between PVP and Au NPs features at different annealing temperatures.