Resonant photothermal laser processing of hybrid gold/titania nanoparticle films

•Photothermal processing of TiO2 and hybrid Au/TiO2 nanoparticles using continuous-wave lasers is demonstrated.•Processing of TiO2 nanoparticles at 355nm results in a transition from anatase to rutile.•Decoration of TiO2 nanoparticles with Au nanoparticles results in an increased absorbance in the visible range.•Hybrid Au/TiO2 nanoparticles can be processed at 355nm and 532nm in a large laser parameter window.•Processing of hybrid Au/TiO2 nanoparticles at 532nm can be carried out at low laser powers and short laser pulse lengths. Photothermal processing of thin anatase TiO2 and hybrid Au/anatase TiO2 nanoparticle films on glass supports is investigated using continuous-wave microfocused lasers at λ=355nm and λ=532nm. UV/Vis spectroscopy, Raman spectroscopy, optical microscopy, atomic force microscopy and scanning electron microscopy are used for characterization. Processing of TiO2 nanoparticle films is feasible at λ=355nm only. In contrast, the addition of Au nanoparticles enhances the overall absorbance of the material in the visible range and enables processing at both wavelengths, i.e. at λ=355nm and λ=532nm. Generally, laser heating induces a transition from anatase to rutile. The modification degree increases with increasing laser power and laser irradiation time. Resonant laser processing of hybrid Au/TiO2-mesoporous films provide promising perspectives in various applications, e.g. in photovoltaics, where embedded nanoparticulate Au could be exploited to enhance light trapping.