Effect of substrate pre-treatment on microstructure and enhanced electrochromic properties of WO₃ nanorod arrays

Abstract

WO3 nanorod arrays (WNRAs) were successfully synthesized on an FTO substrate pre-coated with a layer of TiO2 seeds.

Fabrication of Mo-Doped WO3 Nanorod Arrays on FTO Substrate with Enhanced Electrochromic Properties

“…According to an as-reported method [ 22 ], the FTO substrates were pre-coated with a TiO 2 seed layer by spin-coating using TiO 2 colloid solution and then annealed in air. In brief, tetrabutyl titanate (TBT, China National Pharmaceutical Group Corporation, Beijing, China), as the initial reactant, was first dissolved in ethanol and is denoted as Solution A.…”

“…The final composition of the TiO 2 colloid in a molar ratio was TBT/H 2 O/HCl/ethanol = 1:1.2:0.15:20. After that, the obtained TiO 2 colloid solution was dropped onto the conductive side of the FTO substrate by spin-coating (KW-4A, made by Institute of Microelectronics of Chinese Academy of Science, Beijing, China) at a speed of 3000 rpm for 30 s. Finally, the as-coated FTO substrates were annealed at 700 °C for 15 min to synthesize the TiO 2 seed layer, the thickness of which is about 200 nm [ 22 ].…”

“…Based on previous reports [ 22 , 28 ], the precursor solutions were prepared for the fabrication of WNRAs as follows. Sodium molybdate dihydrate powder (Na 2 MoO 4 ·2H 2 O) and sodium tungstate dihydrate powder (Na 2 WO 4 ·2H 2 O) were mixed in different molar ratios R Mo/W = 0 (0: 8.25 g), R Mo/W = 1:40 (0.147 g: 8.04 g), and R Mo/W = 1:20 (0.288 g: 7.85 g) and were dissolved in 25 mL of deionized distilled water (DDW).…”

“…Numerous methodologies have been assumed to modify the WO 3 film based on electrochromic devices to increase the coloration efficiency and cyclic stability. Man et al [ 22 ] synthesized WO 3 nanorod arrays on fluorine-doped tin oxide (FTO) substrate and precoated with a layer of TiO 2 seeds. The results showed that WO 3 nanorod arrays synthesized on the TiO 2 seed layer exhibited higher coloration efficiency (142.7 cm 2 /C) and larger optical modulation (77.5%, at 660 nm) compared with those grown on the WO 3 seed layer.…”

“…In the present discussion, Mo-doped WO 3 nanorod array films were synthesized by a hydrothermal method on FTO-coated glass substrates, which was pre-coated with a TiO 2 seed layer in accordance with our previous research [ 22 ]. The effects of the Mo doping amount, hydrothermal temperature, and time on the morphology, structure, and electrochromic properties of as-prepared Mo-doped WNRAs films were systematically investigated.…”