Effect of H2Te2O6 and TeO2 phases on structural and electrochromic properties of WO3-TeO2 nanostructured binary thin films

In this paper, WO3-TeO2 binary thin films were deposited by spray pyrolysis. By changing the stoichiometry between WO3 and TeO2 in initial solution, three samples with various molar ratios were prepared including: (a) WO3 (0.15 M)TeO2 (0.05 M), (b) WO3 (0.1 M)-TeO2 (0.1 M), and (c) WO3 (0.05 M)-TeO2 (0.15 M). Then, deposited binary thin films were characterized by XRD, FE-SEM, and I-V cyclic voltammetry to study electrochromic and coloration properties of the thin films before and after annealing at T = 500 degrees C. The XRD analysis of the samples shows the formation of the H2Te2O6 phase with the preferred peak of (2 0 0), which increased with TeO2 content after annealing. The WO3-TeO2 thin films were used as a binary combination of n-type (WO3) and p-type (TeO2) semiconductors to investigate the change in electrochromic properties before and after annealing at T = 500 degrees C. The results of the hysteresis I-V curve of the WO3-TeO2 binary combination showed that by increasing the H2Te2O6 phase, the electron-hole exchange and, consequently, the coloration/bleaching process are improved. The area under the hysteresis curve varies in the range of 11.02 x 10(-3) to 88.32 x 10(-3) A.V. The diffusion coefficient also varies in the range of 1.96 x10(-12) to 7.09 x10(-12) cm(2)/s.

Automated summary

WO3-TeO2 binary thin films were deposited by spray pyrolysis and characterized to study their electrochromic and coloration properties. Increasing TeO2 content after annealing led to the formation of the H2Te2O6 phase, improving electron-hole exchange and the coloration/bleaching process. The results show variations in hysteresis curve area and diffusion coefficient in response to the changes in TeO2 content.