Vanadium (IV) oxide is one of the most promising materials for thermochromic films due to its unique, reversible crystal phase transition from monoclinic (M1) to rutile (R) at its critical temperature (Tc) which corresponds to a change in optical properties: above Tc, VO2 films exhibit a decreased transmittance for wavelengths of light in the near-infrared region. However, a high transmittance modulation often sacrifices luminous transmittance which is necessary for commercial and residential applications of this technology. In this study, we explore the potential for synthesis of VO2 films in a matrix of metal oxide nanocrystals, using In2O3, TiO2, and ZnO as diluents. We seek to optimize the annealing conditions to yield desirable optical properties. Although the films diluted with TiO2 and ZnO failed to show transmittance modulation, those diluted with In2O3 exhibited strong thermochromism. Our investigation introduces a novel window film consisting of a 0.93 metal ionic molar ratio VO2-In2O3 nanocrystalline matrix, demonstrating a significant increase in luminous transmittance without any measurable impact on thermochromic character. Furthermore, solution-processing mitigates costs, allowing this film to be synthesized 4x-7x cheaper than industry standards. This study represents a crucial development in film chemistry and paves the way for further application of VO2 nanocomposite films in chromogenic fenestration.
@article{arxiv.1709.06944,
title = {Optimizing Thermochromism of Solution-Processed VO$_2$ Nanocomposite Films for Chromogenic Fenestration},
author = {Joel P. Abraham},
journal= {arXiv preprint arXiv:1709.06944},
year = {2017}
}