Solvothermal synthesis and characterization of ultrafine nickel oxide nanocrystals with dual-functional electrochromic/energy storage performance

Ultrafine NiO nanocrystals with an average size of approximately 3.3 nm were synthesized using a controlled solvothermal method. The spin-coated NiO films exhibited remarkable electrochromic properties, including a high contrast (79.7 % at 550 nm), excellent transmittance in the bleached state (98.7 % at 550 nm), and fast coloring (1.6 s) and bleaching (1.9 s) response time. These superior performances can be attributed to the ultrafine grain size and good dispersion of the nanocrystals. Notably, an assembled device demonstrated superior dual-functional electrochromic and energy storage properties. Furthermore, the nanocrystals showed promising potential for microelectronic printing, highlighting their applicability in smart display technology.