Room-temperature fabrication of TiO₂ thin films with enhanced electrochromic performance

The expansion of flexible electronics has intensified the need for high-performance electrochromic films processable at low temperatures. While solution-based methods allow low-cost and large-area fabrication, their required high-temperature calcination step hinders compatibility with heat-sensitive substrates. To overcome this limitation, we employ non-thermal plasma (NTP) technology to achieve the room-temperature (35 °C) crystallization and surface activation of sol-gel derived TiO₂ films, entirely bypassing conventional high-temperature calcination. The resulting films exhibit an integrated combination of electrochromic properties, including a high coloration charge density, fast switching speed, and a large optical modulation of 37.6% at 550 nm, along with excellent cycling stability (31.4% modulation retention after 1000 cycles). This work presents NTP-assisted processing as a versatile, low-temperature route compatible with flexible substrates, laying a material and methodological foundation for the integration of high-performance oxide films into next-generation devices.