Mixed Molybdenum-Tungsten Oxide as Dual-Band, VIS-NIR Selective Electrochromic Material

Energy efficiency of smart windows can be greatly improved by integrating dual-band electrochromic materials based on nanostructured doped metal oxides, as these will allow for a dynamic and independent control of light and heat supplies in buildings respectively related to transmitted visible (VIS) and near-infrared (NIR) solar radiations. Mixed molybdenum – tungsten oxides MoyW1-yO3-δ “MoWOx” are considered as innovative compounds in this context: in comparison with parent WO3-δ formulations, a remarkable increase of unpaired electrons can be obtained from the formation of a larger amount of both reduced species and oxygen vacancies during the synthetic process of MoWOx materials, with a consequently boosted intensity of light absorption by 850-900 nm wavelengths. Consecutively, spin-coated films obtained from MoWOx structures solvothermally synthesized for 1h from 2/1 Mo/W atomic ratios are shown to be electrochromically commutable through a noticeable VIS-darkened and NIR-transparent warm mode, while WO3-δ benchmarks classically evolve between bright (VIS & NIR bleached), cool (VIS-bleached, NIR-opaque) and dark (VIS & NIR opaque) states. All in all, such advanced optical functionalities are of high interest for fine-tuning the selectivity and improving the efficiency of electrochromic fenestration solutions, further improving their capacity to adapt to different climates, seasons, and users preferences.