Vacancy-engineered V2O5-x films for ultrastable electrochromic applications

Abstract

In the present study, we prepared vacancy-engineered V2O5-x films for electrochromic (EC) applications. To investigate the vacancy effect of V2O5-x films with high EC performance capabilities, precursor concentrations of V-based sol solutions were varied at 1 wt%, 5 wt%, and 10 wt%. Among them, V2O5-x films with a precursor concentration of 5 wt% (V2O5-5wt%) showed superior EC performance outcomes due to the (001)-plane-oriented crystal structure, which provides high electrical conductivity with the oxygen vacancy (Vo). In addition, the gravel-like uniform surface morphology with the optimized film thickness provides a stable electrochemical reaction during the EC measurement. As a result, V2O5-5wt% exhibited fast switching speeds (2.1 s for coloration and 3.6 s for bleaching), high transmittance modulation (ΔT) (51.32%), high coloration efficiency (CE) (52.3 cm2/C), and excellent cycle stability (85.85% ΔT retention after 500 cycles). In addition, V2O5-5wt% showed energy storage capability of 443.7 F/g at a current density of 2 A/g, thus proving its potential for use in multi-functional applications. Therefore, these results provide valuable insight related to the engineering of vacancies in EC films to achieve high-performance EC devices and additional multi-functional applications.