Oxygen-induced Ag-based binary structure for efficient heat-regulating windows

Abstract

Heat-regulating (HR) windows are essential for net-zero-energy building approaches. Silver (Ag) thin films are preferred for developing high-functioning HR windows because of their unique optoelectrical properties. The quality of the HR windows depends on the tradeoff between the transparency and conductivity of the Ag film. Ultrathin Ag (thickness < 10 nm) obtained using the wetting technique has been universally adopted to overcome this trade-off. However, the use of a wetting layer can hinder the optimum transparency of HR windows because of the possible optical loss associated with the wetting layer. Herein, the partial oxidation technique was thoroughly investigated for fabricating one-step grown Ag used for high-functioning HR windows. The incorporation of oxygen (5.7 % volume) during Ag sputtering allowed the direct growth of continuous Ag film on substrates with a percolation threshold below 4 nm. Partial oxidization of Ag resulted in modulated optical coefficients of Ag, thereby facilitating the ease of developing AZO/Ag (6.5 nm)/glass with optimum transparency of 98 % and sheet resistance of 12 Ω sq−1. AZO/Ag/glass possessing a high Haacke figure of merit 68.1 (10−3 Ω−1) was developed for HR windows, with the capability of providing a temperature discrepancy of 2 °C for different simulated weather conditions.