SOLUTION-BASED PROCESSING FOR VANADIUM DIOXIDE THIN FILMS: IMPROVED THERMOCHROMISM AND LOW EMISSIVITY PROPERTIE

摘要

Vanadium dioxide is a key material for thermochromic smart windows that can response to environmental temperatures to modulate near infrared irradiation while maintaining high visible transmittance. However, because of the insufficiency in conductivity for VO_2, the emissivities of VO_2/glass windows are usually too high, which causes energy loss accompanied by the process of thermal exchanging between the interior and the exterior of the buildings. Moreover, the issues of low visible transmittance, weak modulation efficiency in the NIR region should also be addressed, before they can be applied efficient energy saving apparatus. In this work, a modified polymer-assisted deposition (PLD) method was developed for the deposition of single-layered VO_2 and TiO_2/VO_2/FTO multi-layered thin films. The investigation indicated that the incorporation of nano/meso scale porous microstructures synchronistically improved the visible transmittance and the NIR modulation abilities for the VO_2 films. Based on optical designs, a triple-layered TiO_2/VO_2/FTO structure was proposed and experimented to boost the thermochromic properties and the low-emissivity performance. ANIR modulation efficiency of 8.8% and emissivities of 0.13 and 0.24 before and after MIPT were obatained, which demonstrate a new approach of combining both thermochromism and low-emissivity performance for applications such as VO_2-based energy-saving windows. This study was supported in part by funding from the China Postdoctoral Science Foundation (Contract No. 2012M521406), the Open Fund of Key Laboratory of Inorganic Coating Materials, Shanghai Institute of Ceramics, Chinese Academy of Sciences (Contract No. SKL201310SIC) and the Key Science and Technology Research Projects of Henan Provincial Education Department (Contract No.: 14B430023).