Design of Structural and Chemical Disorder in Metal Oxide Thin Films for Enhanced Light Absorption (EnLight)

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The interdisciplinary project - EnLight - will develop innovative materials modification processes to improve the light-management properties of metal oxide semiconductor films by laser-assisted periodic surface structuring (correlated disorder) of SnO2, TiO2, CeO2 films grown by atomic layer deposition (ALD) and chemical vapor deposition (CVD) techniques. In addition, plasma-assisted surface reduction of the above-mentioned metal oxide surfaces will be undertaken to induce valence-exchange and chemical gradient in the films that have been reported to drastically alter the optical and electrical properties. The focused nature of laser beams and random nature of plasma plume will allow evaluating tailored disorder against random disorder in terms of optical and electrical properties. This effort is focused to demonstrate that correlated structural disorder created by laser-assisted patterning of metal oxides nanolaminates and chemical (phase) disorder locally induced by chemical transformations that can create composite structures, for instance, metal nanostructures embedded in oxide matrices that can modify the optical properties such as refractive index and haze value, by transforming bimetallic oxides (e.g. spinels M'M''2O4) into M/M2O3 composites by laser irradiation. Starting from the fabrication of phase pure thin films with low defect concentration using CVD and ALD approaches, laser and plasma modification will be carried out, supported by in depth chemical, structural and functional characterization as well as simulation of laser irradiation effects to gain a detailed insight into the underlying reaction mechanisms of disorder formation. Finally the structured substrates will be tested as components in organo-lead-halide perovskite solar cells to elucidate the potential of tailored disorder in a working prototype. The expertise gained in this project will serve as a platform for other members of the Priority Program 1839 for tailored disorder of metal oxide thin films, which can be extended to flexible substrates.