Scalable wavelength-selective solar absorber based on refractory TiN nanostructures.

Scalable wavelength-selective solar absorbers with both high selectivity and thermostability are desired for efficient utilization of solar thermal energy. In this study, we present a refractory titanium nitride (TiN) moth-eye-like nanostructure, fabricated via oblique deposition, that provides high solar light absorptivity (0.9) and low emissivity (0.17) at 100 °C under atmospheric conditions. The strong visible-light absorption of the structure is complemented by a Fabry-Pérot resonance that broadens the strong absorption band into the near-infrared light region for certain structure dimensions. In addition, TiN is a promising material, due to its refractory nature, having a very high melting point of 2930 °C. The oblique deposition method used to obtain the nano-structured TiN does not require the use of lithographic techniques or expensive nano-templates, thus it is suitable for large-scale fabrication. The nanostructure and its fabrication method have significant potential for practical applications requiring efficient use of solar light energy.