Scalable Fabrication of Heat Tolerant Titanium Nitride Nanoring Structures with Multiple-Patterning Colloidal Lithography for Broadband Absorbers in the Visible to Near-Infrared

Broadband perfect absorbers have been researched intensively for decades for their near-perfect absorption optical property which can be applied to various applications. However, achieving large-scale and heat-tolerant absorbers has been remained challenging work because of costly and time-consuming lithography methods and thermolability of materials, respectively. Herein, we demonstrate a thermally robust titanium nitride broadband absorber which has a polarization-independent absorption of 95.4% under normal incidence angle in average and high absorption at incident angles up to θ = 40^o at visible and NIR wavelength (400 < λ < 900 nm). The near-perfect absorption of our device is still maintained even after heating at the temperatures ＞600 ^oC. Such a large-scale, heat-tolerant, and broadband near-perfect absorber will provide further useful applications in solar thermophotovoltaics, stealth, and absorption controlling in high-temperature conditions.