Facile Solution Synthesis of Tungsten Trioxide Doped with Nanocrystalline Molybdenum Trioxide for Electrochromic Devices

Abstract

A facile, highly efficient approach to obtain molybdenum trioxide (MoO3)-doped tungsten trioxide (WO3) is reported. An annealing process was used to transform ammonium tetrathiotungstate [(NH4)2WS4] to WO3 in the presence of oxygen. Ammonium tetrathiomolybdate [(NH4)2MoS4] was used as a dopant to improve the film for use in an electrochromic (EC) cell. (NH4)2MoS4 at different concentrations (10, 20, 30, and 40 mM) was added to the (NH4)2WS4 precursor by sonication and the samples were annealed at 500 °C in air. Raman, X-ray diffraction, and X-ray photoelectron spectroscopy measurements confirmed that the (NH4)2WS4 precursor decomposed to WO3 and the (NH4)2MoS4–(NH4)2WS4 precursor was transformed to MoO3-doped WO3 after annealing at 500 °C. It is shown that the MoO3-doped WO3 film is more uniform and porous than pure WO3, confirming the doping quality and the privileges of the proposed method. The optimal MoO3-doped WO3 used as an EC layer exhibited a high coloration efficiency of 128.1 cm2/C, which is larger than that of pure WO3 (74.5 cm2/C). Therefore, MoO3-doped WO3 synthesized by the reported method is a promising candidate for high-efficiency and low-cost smart windows.

Highly stable electrochromic cells based on amorphous tungsten oxides prepared using a solution‐annealing process

“…Figure 2B shows the W 4f XPS spectra of the film annealed at 250°C, and two doublets centered at approximately 36.2 and 38.3 eV can be observed. These peaks corresponded to the binding energies of W 4f 5/2 and W 4f 7/2 of W 6+ as stated in previous reports 52,53 . These peaks could be well‐fitted into two peaks and demonstrated that the tungsten ions were well oxidized to W 6+ .…”

“…These peaks corresponded to the binding energies of W 4f 5/2 and W 4f 7/2 of W 6+ as stated in previous reports. 52,53 These peaks could be well-fitted into two peaks and demonstrated that the tungsten ions were well oxidized to W 6+ . As shown in Figure 2C, two O 1 second peaks located at approximately 531 and 532.7 eV were observed.…”

Tungsten Trioxide Doped with CdSe Quantum Dots for Smart Windows

“…Moreover, the XRD spectrum of WO 3 confirmed the monoclinic crystal structure and the corresponding peaks are similar to those reported previously. 18,19,31 On the other hand, the XRD spectrum of CdSe QD (20 s reaction time)−WO 3 confirms the changes in crystal structure of the film and the penetration of CdSe QDs into the WO 3 crystal, producing a new phase that corresponds to the orthorhombic crystal structure. 19,32,33 Figure 2d shows the FE-SEM images and surface morphology of the CdSe QD (20 s reaction time)−WO 3 and pristine WO 3 (inset).…”

“…Furthermore, there have been some efforts to modify the electrochromic performance of WO 3 film for practical applications. 18,19 For example, Cai et al investigated the effect of Ti dopant for enhanced electrochromic performance of WO 3 layer. 20 An efficient performance with appropriate coloration efficiency (CE) (68 cm 2 /C at 750 nm) and rapid response time (1.…”

“…In our previous works, we synthesized metal and molybdenum triode-doped WO 3 for smart windows. 19 The CdSe QDs were prepared via a facile and fast method from cadmium oxide (CdO) and Se, i.e., a controllable process in which the dimension depends on the reaction time. 27 Next, an ammonium tetrathiotungstate ((NH 4 ) 2 WS 4 ) precursor was mixed with the as-prepared CdSe QDs.…”