Fuel-assisted solution route to nanostructured nickel oxide films for electrochromic device application.

In this work, nanocrystalline NiO films were prepared using the fuel-assisted solution method. The microstructure of the NiO film can be modulated by the addition of thiourea fuel. The size of NiO nanocrystals in the NiO film decreased with increasing amount of thiourea in the precursor solution. Compared to the film prepared without thiourea addition, the thiourea-assisted NiO film had enhanced electrochromic properties, including larger transmittance modulation, larger coloration efficiency, faster response time, and superior reliability. Electrochemical impedance spectroscopy measurements indicate that faster charge transfer occurs at the interface between the electrolyte and the fuel-assisted NiO films, which results in improved electrochromic behavior.