Smart windows possess the potential to contribute significantly to reducing the world-wide energy consumption in the future. The properties of the thermochromic metal oxide VO2 are closest to the material requirements set by economic considerations for the use as an active layer in thermochromic glazings. We show that the required parameters can be achieved by modifying VO2 on the atomic level, i.e., by simultaneous co-doping with Sr and W on the cation site. In particular, the transition temperature ϑc can be adjusted in the range between 15 and 68 °C by varying W contents, whereas the incorporation of Sr mainly increases the band gap yielding a greyish color of the films. Interestingly, the simultaneous presence of W and Sr enhances both effects. The co-doping leads to values of the luminous transmittance Tlum and the solar transmittance Tsol fulfilling the requirements set by application. The variation of the solar transmittance ΔTsol of the plain thin films on a glass substrate already is larger than 5% for all samples promising that the required value of ΔTsol=10% is achievable by using such thin films as part of an optically engineered multilayer system.

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Lithium phosphorous sulfuric oxynitrides (LiPSON) with different compositions have been prepared by rf-sputtering using sputter targets with various mixtures of Li 3 PO 4 and Li 2 SO 4 . Morphology, composition, and electrochromic properties of the fabricated thin films were investigated using solid state analysis methods like scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), optical transmission spectroscopy, and electrochemical impedance spectroscopy. The composition of the thin films changes due to the varying fractions of process gases. The highest fraction of sulfur is about 1.3 at% validated using XPS. The optical bandgap shifts in the range of 3.7 eV up to 5.3 eV for the different fractions of process gases. Transmission in the UV range is above 60% for most of the sputtered solid electrolyte thin films whereas in the visible range of the electromagnetic spectrum a transmission above 80% is observed. The highest ionic conductivity is identified for the thin films with 4 sccm nitrogen and no additional argon as process gas. However, ionic conductivity is expected to increase with increasing sulfur content and with change of the ratio between different nitrogen coordinations.

Vanadium–oxygen materials are of interest for various applications and fields of solid‐state physics owing to the unequaled plethora of different phases. The wealth of phases and complexity of its phase diagram infer a strong sensitivity on the growth parameters for each phase. Thus, the reproducible growth of vanadium‐oxide thin‐films of defined phases by nonequilibrium techniques is challenging. Here, it is shown that ion‐beam sputter‐deposition (IBSD) is a powerful tool to reproducibly deposit defined polycrystalline vanadium oxide films by precisely controlling oxygen flux and substrate temperature in the growth process. Hence, it is demonstrated that IBSD has the potential to reliably produce binary phases (including unstable phases) from the vanadium–oxygen phase space. X‐ray diffraction (XRD) and Raman spectroscopy are used to establish a map of the different crystalline phases dependent on the growth parameters. In particular, it is proved that thin‐film V3O7 can be realized by IBSD and its Raman fingerprint is unambiguously identified.

Systematic spectroscopic ellipsometry investigations have been performed in order to elucidate the asymmetric insulator-to-metal transition in thin VO2 films. The comprehensive analysis of the obtained macroscopic optical response yields a hysteretic behavior, and in particular its asymmetry, when performed in the framework of an anisotropic effective medium approximation taking into account the volume fraction of the metal inclusions as well as their shape. We reveal the microscopic details of the percolation transition, namely that the shape of the metal inclusions goes through several plateaus, as seen in the evolution of the shape factor on both sides of the transition region and resulting in different critical volume fractions at the transition for the heating and cooling cycles.