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

Abstract 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.