Tuning the phase transition temperature, electrical and optical properties of VO2 by oxygen nonstoichiometry: insights from first-principles calculations
Abstract
Vanadium dioxide (VO2) is one of the most promising thermochromic materials with a reversible metal–insulator transition (MIT) from a high-temperature rutile phase to a low-temperature monoclinic phase, although a high MIT temperature (Tc) of 340 K for bulk VO2 restricts its wide application. Our first-principles calculations show that the oxygen nonstoichiometry plays an important role in tuning the MIT behavior of VO2. The O-vacancy in bulk VO2 gives rise to an increase in electron concentration, which induces a decrease in Tc. On the other hand, O-vacancy and O-adsorption on VO2(R) (1 1 0) and VO2(M) (0 1 1) surfaces could alter their work functions and in turn regulate Tc. In addition, the formation and adsorption energies of O-adsorption on the two types of surfaces are negative, indicating that VO2 surfaces are prone to oxidation in ambient air. The present results contribute to both tuning phase transition behaviors experimentally and reducing hindrances for the advanced applications of VO2-based materials.
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