Tailoring Optical Properties in Transparent Highly Conducting Perovskites by Cationic Substitution.

SrMoO3 , SrNbO3 , and SrVO3 are remarkable highly conducting d1 (V, Nb) or d2 (Mo) perovskite metals with an intrinsically high transparency in the visible. A key scientific question is how the optical properties of these materials can be manipulated to make them suitable for applications as transparent electrodes and in plasmonics. Here, it is shown how 3d/4d cationic substitution in perovskites tailors the relevant materials parameters, i.e., optical transition energy and plasma frequency. With the example of the solid-state solution SrV1- x Mox O3 , it is shown that the absorption and reflection edges can be shifted to the edges of the visible light spectrum, resulting in a material that has the potential to outperform indium tin oxide (ITO) due to its extremely low sheet resistance. An optimum for x = 0.5, where a resistivity of 32 µΩ cm (≈12 Ω sq-1 ) is paired with a transmittance above 84% in the whole visible spectrum is found. Quantitative comparison between experiments and electronic structure calculations show that the shift of the plasma frequency is governed by the interplay of d-band filling and electronic correlations. This study advances the knowledge about the peculiar class of highly conducting perovskites toward sustainable transparent conductors and emergent plasmonics.

Band engineering for efficient catalyst-substrate coupling for photoelectrochemical water splitting.

To achieve an overall efficient solar water splitting device, not only the efficiencies of photo-converter and catalyst are decisive, but also their appropriate coupling must be considered. In this report we explore the origin of a voltage loss occurring at the interface between a thin film amorphous silicon tandem cell and the TiO2 corrosion protection layer by means of XPS. We find that the overall device can be disassembled into its primary constituents and that they can be analyzed separately, giving insight into the device structure as a whole. Thus, a series of model experiments were conducted, each representing a part of the complete device. We finally arrive at the conclusion, that the formation of a SiO2 interfacial layer between the TiO2 protection layer and the silicon cell gives rise to the voltage loss observed for the whole device.