Environmental assessment of electrically controlled variable light transmittance devices

A comprehensive benchmark analysis has been performed on five electrically controlled state-of-theart transmittance modulation devices including their production routes, from 'cradle-to-gate'. The benchmarks have been modeled employing the GaBi life cycle assessment software tool, which successfully yielded the most important environmental problem areas for the product life cycles of electrochromic and electrotropic light-modulating devices. In terms of the energy demand of processing, all-solid-state technology was found to be less favorable than wet-chemical electrodeposition processes; however, the effect is interestingly overcompensated for by the resource depletion resulting from higher layer thicknesses in the latter case. As opposed to the mineral-glass based benchmarks, a plastic-film based system was particularly favorable, implying that the substrate is a factor with a strong environmental impact in transmittance modulation devices. Eventually, very high impacts were found for tin-doped indium oxide (ITO) and iridium oxide, i.e. a common transparent conductor and anodic electrochromic material, respectively. The results obtained support important current trends such as in-line manufacturing of electrochromic devices, the quest for ITO replacement materials, and, in general, the replacement of energy- and resource-intensive processes (sputter deposition of heavy metal oxides) by less demanding methods

TiO2/AZO bilayer thin films by magnetron sputtering as transparent electrodes for electrochromic devices

Transparent electrodes are dominated by a single material indium tin oxide (ITO). Indium has been classified as a critical raw material by the EU, thus some alternative transparent conductor materials are urgently required. Aluminum zinc oxide (AZO) has emerged as promising substitute due to its high transmittance and low resistivity as well as its low cost and resource availability. However, manufacturing processes for some optoelectronic devices such as electrochromic devices or organic light emitting diodes, chemically attack the AZO layers due to their instability against acidic and basic solutions. Chemical and environmental stability of AZO coatings must be improved to guarantee long-term stability of the devices. In this paper, electrochromic devices based on viologen modified nanostructured TiO2 layers have been manufactured on bilayer electrodes formed by sputtering TiO2 protective films on AZO layers. A thin sputtering TiO2 layer does not electrically insulate the AZO but improves its stability and protects it from being attacked during the deposition of the nanostructured sol-gel TiO2, enabling the fabrication of EC devices that switch properly between a transparent, colorless and a green coloured state. Optical contrast (ΔT %) values up to 40% have been reached with an operating voltage of −1.5 V

Sb‐Substituted Cs 2 AgBiBr 6 —As Much As It Could Be?—Influence of Synthesis Methods on Sb‐Substitution Level in Cs 2 AgBiBr 6

Sb-substituted Cs2AgBiBr6 single crystals and powders are synthesized by various wet-chemical routes as well as by solvent-free mechanochemical synthesis. Phase purity and resulting optical properties of differently synthesized Sb-substituted Cs2AgBiBr6 absorbers are investigated and compared. X-ray diffraction confirms that Sb substitution results in an apparent single-phase formation with a unit cell shrinkage up to a certain substitution limit, which varies depending on the synthesis routes. Questions about the phase identification determined by X-ray diffraction are raised and thoroughly investigated by Raman spectroscopy. UV–vis spectroscopy reveals that Sb3+ substitution induces a reduction in the optical bandgap of Cs2AgBiBr6, whereas octahedral factor calculations provide that SbBr6 octahedra can be hardly stable in a Cs2AgBiBr6 double perovskite. The experimental results of the occurrence and evolution of Raman bands and theoretical calculations of the structural stability of SbBr6 octahedra in Cs2AgBiBr6 unambiguously raise doubts about the Sb-substitution feasibility in Cs2AgBiBr6, and a general substitution strategy in Cs2AgBiBr6 is discussed