Electrochromic device with hierarchical metal mesh electrodes: Transmittance switching in the full spectral range of solar radiation

Hierarchical metal mesh structures are fabricated for use as transparent conductive electrodes in electrochromic devices with large-band transmittance switching. Electrochromic materials (WO<inf>3</inf> and Ta:NiO) are deposited by plasma sputtering on the metal mesh and characterized in a custom-made electrochemical setup allowing in-situ photo-spectrometer measurement. Both films deposited on metal mesh exhibit high transmittance, not only in the visible but also in the NIR spectrum. Electrochromic devices based on the WO<inf>3</inf> cathode and Ta:NiO anode combined with the hierarchical metal mesh are fabricated. The resulting device achieves remarkable optical modulation in the full spectral range of solar radiation compared to conventional ITO-based devices. This study paves the way for development of hierarchical metal mesh-based electrochromic devices which offer high potential for energy savings through wide band modulation of solar heat gain in buildings in countries with warm and cold seasons.