Realization of high luminous transmittance and solar modulation ability of VO2 films by multistep deposition and in-situ annealing method

Abstract

Novel VO2(x nm)/VO2(x nm)/VO2(x nm) (x = 10, 14, 16, 20) trilayer films are proposed and prepared on quartz glass substrates via multistep devotion and in-situ annealing by pulsed laser deposition. The bottom, intermediate and top VO2 layers are distinguished by different thickness and annealing time. The characterization of FESEM and AFM showed that grain size and surface roughness of VO2 films increase gradually from the bottom to top layer. The trilayer structure has little effect on phase transition temperature of VO2, but hysteresis width can be tuned in the range of 11–27 °C. The luminous transmission and solar modulation ability of VO2(16 nm)/VO2(16 nm)/VO2(16 nm) trilayer film were remarkably enhanced to 55.7% and 8.0%. The results suggested that such an enhancement can be attributed to the well matching of grain size of the bottom, intermediate and top VO2 layers. The study in this work provide a simple and promising strategy for designing high-quality VO2-based smart windows without additional functional layers.