Thermal radiation analysis of a broadband solar energy-capturing absorber using Ti and GaAs

This study employed a time-domain finite-difference (FDTD) approach to design an efficient solar energy-capturing absorber consisting of a high melting point metal (Ti) and a semiconductor (GaAs). The structure generated cavity resonance (CR) and surface plasmon resonance (SPR), leading to extremely high absorption across different wavelength bands. The structure exhibited >90% absorption over a wide wavelength range (280-3000 nm). It achieved an average absorption efficiency of 97.0% in the wavelength range from 280 nm to 3000 nm at an air mass of 1.5 (AM1.5). The structure showed insensitivity to the angle of incidence, maintaining stable absorption of over 94% for angles of incidence ranging from 0° to 60°. The structure could also operate at 1400 K, with thermal radiation efficiencies of up to 98.2%. As the operating temperature increased from 600 K to 1400 K (with a temperature gradient of 200 K), the thermal radiation efficiency of the structure remained above 98% at all times. Based on the excellent radiation and absorption properties of this absorber, it holds promising application in the fields of solar energy absorption and thermal emission.