Work

Energy-efficient W-doped VO2-based smart glasses by glancing angle co-deposition and subsequent rapid thermal annealing

Year: 2025

Type: article

Abstract: This work reports on an original approach to the fabrication of W-doped VO 2 -based coatings of 25 and 50 nm nominal layer thickness which comprises the initial co-deposition, at glancing angles and in the presence of reactive oxygen, of alternating VO y /V 0.85 W 0.15 O y multilayers with average W/V ratios between 1/99 and 5/95, and their subsequent rapid thermal annealing in air atmosphere. Exhaustive micro- and nanostructural, compositional, and optical characterizations of samples treated at reaction temperatures of 475 and 550°C for times below 30 s confirmed the synthesis of homogeneous V x W 1- x O 2 -based films with unique thermochromic features strongly dependent on the dopant amounts. In general, a gradual lowering of the critical temperature to 37°C during heating was achieved for a maximum intended doping of x = 0.95, albeit at the expense of some detriments in optical performances. The best and most balanced results were accomplished in a 50 nm nominal thickness layer deposited with overall x = 0.97 (i.e. ∼1 at% W) subjected to flash annealing at 550°C, presenting a remarkable balance of light transmittance (52.0%), solar modulation capability (5.2%) and critical temperature drop (44°C), which leads to a temperature drop rate of about 20 °C per at% W attempted, taking as reference its undoped counterpart fabricated under the same conditions. In addition, the hysteresis width and smoothness achieved make this coating potentially suitable for application in glazing exposed to direct solar radiation. The proposed methodologies, involving doping by purely metallic precursors and green-like reactions, postulate as an attractive, plausible and cost-effective alternative for large-scale manufacturing of VO 2 (M)-based smart coatings.

Source: Results in Engineering

DOI: 10.1016/j.rineng.2025.106323