VO2 microcrystals as advanced smart window material at semiconductor to metal transition

TL;DR

This study investigates VO2 microcrystals' phase transition properties, optical changes, and potential for smart window applications, emphasizing visible light management and thermochromic behavior.

Contribution

It demonstrates the optical and electrical property changes of VO2 microcrystals during phase transition, highlighting their suitability for advanced smart window technology.

Findings

VO2 microcrystals change color from white to cyan at transition.

Absorption of red light explained by Hubbard state transitions.

VO2 shows potential for visible light management in smart windows.

Abstract

Textured VO2(011) microcrystals are grown in the monoclinic, M1 phase which undergo a reversible first order semiconductor to metal transition (SMT) accompanied by a structural phase transition to rutile tetragonal, R phase. Around the phase transition, VO2 also experiences noticeable change in its optical and electrical properties. A change in color of the VO2 micro crystals from white to cyan around the transition temperature is observed, which is further understood by absorption of red light using temperature dependent ultraviolet-visible spectroscopic analysis and photoluminescence studies. The absorption of light in the red region is explained by the optical transition between Hubbard states, confirming the electronic correlation as the driving force for SMT in VO2. The thermochromism in VO2 has been studied for smart window applications so far in the IR region, which supports the opening of the band gap in semiconducting phase; whereas there is hardly any report in the management of visible light. The filtering of blue light along with reflection of infrared above the semiconductor to metal transition temperature make VO2 applicable as advanced smart windows for overall heat management of a closure.