Structure and process engineering for efficient thermochromic transition of vanadium dioxide thin films

Abstract

Thermochromic materials are capable of a reversible change in optical transmittance and electrical resistance in response to temperature. Vanadium dioxide ($VO_2$) is one of the most promising thermocrhomic materials their distinctive switching of optical and electrical characteristics due to an abrupt semiconductor-metal transition at a critical temperature from monoclinic to tetragonal phase. Thermochromic has the potential to be used for a number of applications, including smart windows, infrared sensors or detectors, and Mott transistors. In particular, thermochromic windows effectively reduced the energy consumption in the buildings because phase transition regulates the solor irradiation in a wavelength of 800-2500 nm. Although there has been rapid progress in thermochromic behaviors, there still remain challenges to be solved for transition efficiency, visible transmittance, transition temperature, and fabrication process to achieve highly desirable for low cost industrial production. In this thesis, we study the engineering of structure and fabrication process of the $VO_2$ thin films and on the high transition efficiency by optimization of process parameter and lattice mismatch, high optical transparency with anti-reflection structure, co-doped $VO_2$ thin films, and low process temperature with high density plasma techniques by RF-superimposed DC, and solution-based synthesis of the $VO_2$ thin films with nanopatterns for the industrially favorable process. The thermochromic materials are next-generation smart windows devices, which can be highly useful for the further improvement of efficiency in thermochromic and the realization of high energy saving efficiency.