Advanced Dual-Band Smart Windows: Inorganic All-Solid-State Electrochromic Devices for Selective Visible and Near-Infrared Modulation

Dual-band electrochromic smart windows (DESWs), capable of actively and selectively modulate visible (VIS) light and near-infrared (NIR) heat, have emerged as a practical technology for enhancing user comfort and reducing building energy consumption. However, the design and development of DESWs remain a significant challenge due to the difficulty in obtaining suitable materials and high-durability electrolytes. Here, the first all-solid-state DESW based on an orthorhombic oxygen-deficient tungsten oxide (o-WO_3-x) film is presented. Benefiting from the synergistic effects of the efficient oxygen-vacancy-enhanced charge transfer process and the secure transfer pathway enabled by the orthorhombic crystal structure, the o-WO_3-x film showcases remarkable dual-band electrochromic properties, including selective modulation of VIS light and NIR heat, large optical modulation (89.1%), rapid response time (t_b/t_c = 6.8/17.9 s), high coloration efficiency (155.92 cm² C⁻¹), and ultrastable cyclic performance (8000 cycles) even in acidic aqueous electrolyte. Furthermore, the all-solid-state DESWs incorporating o-WO_3-x deliver a significant and stable dual-band electrochromic response with excellent thermal regulation and energy-saving capabilities. These findings underscore the considerable potential of o-WO_3-x films and their all-solid-state smart windows in decreasing building energy consumption.