Development of Ti-N-O-based multilayer low-emissivity coatings through air-based sputtering technique

A facile approach for depositing low-emissivity (low-e) coatings based on Ti-N-O multilayers was developed using an air-based sputtering technique in a single batch process. By systematically optimizing the TiN(O) thickness and sheet resistance using the Taguchi method, we produced a-TiN x O y /TiN(O)/a-TiN x O y (where a denotes amorphous) multilayer thin films. Spectroscopic ellipsometry revealed that TiN(O) exhibits a lower refractive index and higher extinction coefficient, while amorphous TiN x O y shows a higher refractive index and negligible extinction coefficient. This contrast supports improved optical interference effects in the multilayers. The optimized films demonstrate a balanced performance of infrared reflectivity (44.3–67.5 % at 2 μm), visible transmittance (30.1–59.4 % at 550 nm), and low thermal emittance (0.30–0.57), comparable to reference high-vacuum sputtered TiO 2 /TiN/TiO 2 multilayers. Microstructural and compositional analyses confirmed the formation of well-defined multilayer architectures, where TiN(O) enhances infrared reflectivity and conductivity, and amorphous TiN x O y improves visible-light transmittance and chemical stability. Compared to previously reported TiN-based coatings, our air-based sputtered multilayers achieve substantially higher figures of merit than previously reported TiN-based single-layer and multilayer coatings. These results highlight the effectiveness of air-based sputtering and the Taguchi optimization approach for scalable, cost-effective production of high-performance low-e coatings suitable for energy-efficient applications.