Design and realization of neutral-tinted low-E film

Current Ag-based low emissivity (low-E) film applied in building field brings a forthcoming problem of light pollution. The demanding for colorless low-E film product is increasing. In this work, double silver low-E film (ZTO/Ag/ZTO/Ag/ZTO) with neutral-tinted appearance is designed and replicated on float glass by magnetron sputtering deposition. Annealing treatment is followed after film preparation. Additional film with structure of ZTO/Ag/Ti/ZTO/Ag/Ti/ZTO is simultaneously prepared to protect Ag layer from being oxidized. Most films are more or less in blueish or greenish except the annealed ZTO/Ag/Ti/ZTO/Ag/Ti/ZTO film. The results of sheet resistance and optical spectra qualify the prepared films possessing low-E characteristics. Simulation assumes the optical appearance change differing from original design is induced by fluctuation in film structure. Transmission Electron Microscope (TEM) observation demonstrates Ag layers are ∼ 2 nm thickened in prepared blueish/greenish low-E films. Energy Dispersive Spectroscopy (EDS) analyzing indicates this thickness thickening is caused by layer diffusion during film preparation. Whereas, Ti blocking layer can successfully inhibit Ag diffusion by self-sacrificial oxidation. Consequently, annealed ZTO/Ag/Ti/ZTO/Ag/Ti/ZTO film is turned into ZTO/Ag/TiOx/ZTO/Ag/TiOx/ZTO which preserves the Ag layer thickness and structure feature as designed. Accordingly, neutral tinted low-E film is achieved.