Amorphous and porous C/N-doped NiO for electrochromic smart windows applications

Nickel oxide (NiO), an electrochromic (EC) material, has been extensively used in various fields such as smart energy-saving windows, intelligent displays, and anti-counterfeiting technologies. However, crystalline NiO exhibits some drawbacks that hinder its practical applications. In this research, we successfully synthesized amorphous and porous C/N-doped NiO films through a two-step process. The process involved the formation of a complex between acetate tetrahydrate and monoethanolamine, followed by spray coating and calcination. The resultant C/N-doped NiO films demonstrated exceptional EC properties, including a high optical modulation of 57.7 % at 500 nm, rapid coloration and bleaching times of 7 and 11 s, respectively, and an ultra-high coloring efficiency of 108.2 cm 2 /C. Furthermore, the films exhibited remarkable cycling stability, maintaining a transmittance of 63.1 % after 500 cycles. Notably, when applied to smart windows, these films reduced the temperature of room center by 14.3 °C compared to traditional double-glazed windows. This study introduces a promising material for EC smart windows and display applications, advancing the field beyond previously reported methods.