LAUSR

The authors demonstrate a significant effect of ZnO-nanorod buffer layers on the growth of extremely thin VO2 films. Highly c-axis oriented ZnO-nanorods were grown on glasses with sputtered ZnO-seed layers by using the chemical bath deposition method. Introducing an organic compound, (CN2)6N4 (hexamethylenetetramine), together with a Zn source, Zn(NO3)2, achieved highly c-axis oriented ZnO-nanorods with an average diameter of around 150 nm. Due to such a superior template, b-axis oriented VO2 films were grown on the ZnO-nanorod buffered glasses even with the film thickness lower than several tens of nanometers. The thinnest VO2 film emerged in insulator-metal transition, achieving high visible-light transmittance and clear infrared-light switching, which are characterized by luminous transmittance (Tlum) of 56% even at metallic state and solar modulation ability (ΔTsol) of 6.0%. The results obtained in this study propose a way to achieve practical smart windows that enable not only infrared-light switching but also maintaining high visible-light transmittance without any optical design.