Microstructural Control of the Electrochromic and Ion Storage Layers on the Performance of an Electrochromic Device Fabricated by the Kinetic Spray Technique

WO3 electrochromic (EC) and ATO ion storage films were fabricated by a kinetic spray technique at various substrate heating temperatures. The optimal heating condition for WO3 deposition was 80oC, which provided a total transmittance change of 31%. Furthermore, the total transmittance change (at 800 nm) of the WO3 EC cell fabricated with the ATO ion storage layer deposited at 150°C was 42%, which was caused a comparably large shift in the transmittance. The charge/discharge density of the EC cell with the ATO ion storage layer deposited at 150°C was 11.12-11.37 mC cm-2. Finally, the cyclic transmittance of 40% was maintained for 1 h. The uniform and densely packed microstructure that resulted from the heated substrate had good inter-grain and particles connections that provided sufficient absorption sites for ions. Therefore, it was established that microstructural control of the EC and ion storage layers are crucial to improving EC performance.