High energy efficient and thermally stable solar selective absorber constructed with TiN_xO_y based multilayers

Solar selective absorbers are the most critical part of solar water heaters that can be integrated into architecture. A high-performance absorber with a solar absorptance α higher than 95% and an infrared emissivity e below 4% is fabricated by sputtering using TiN_xO_y based multilayers. The highest absorptance is 97.5% and the corresponding energy utilization efficiency (α/e) value is as high as 26.2. The absorber has excellent thermal stability that can maintain its property after heating at 400 °C for 100 hr in air. It can even be tempered on the glass substrate, which is of great significance for lowering the cost and expanding its applications.