Highly Stable All-Sputtered Solid-State Electrochromic Devices with Co-Sputtered LiTaO₃ Electrolyte Films for Smart Windows

Because of the growing demand for energy efficiency and aesthetic functionality in buildings and automotive windows, solid-state electrochromic (EC) technology is receiving significant attention. However, the conventional LiTaO₃ (LTO)-based electrolyte layers used in EC devices are limitations because of the fabrication complexity and long-term ionic conductivity stability, which hinder their commercial viability. In this study, the challenges faced in the use of EC devices are addressed with conventional LTO-based electrolyte layers by introducing Ta-doped Li₂O-based electrolyte layers with compositional control into the EC devices to obtain highly stable, all-sputtered EC devices with significantly enhanced long-term stability. By systematically analyzing the optical, structural, and electrochemical properties of all-sputtered EC devices with different gas flow ratios, it is demonstrated that the LTO – 6% EC devices exhibited superior optical contrast, rapid response times, and excellent cycling stability. The incorporation of Ta into Li⁺ sites improves the structural stability of the LTO, addressing the inherent long-term degradation of conventional LTO compositions. Moreover, with an average near-infrared transmittance of only 5.72%, these devices are substantial energy-saving potential. This study highlighted the potential of all-sputtered EC devices prepared using all sputtering processes to reduce energy consumption in buildings while enhancing the comfort of their occupants.