Spectrally Selective Ultra-Broadband Solar Absorber Based on Pyramidal Structure

Here, a spectrally selective solar absorber is explored and an ultra-broadband solar absorber is proposed based on pyramidal structure. The finite-difference in time domain (FDTD) software is used to model the spectral characteristics and magnetic absorption patterns of this absorber. The emissivity of the absorber is less than 20% in the far-infrared band over 6000 nm, showing good selectivity, and the total solar thermal conversion efficiency is very close to that of an ideal truncated selective solar absorber by analyzing the performance of our proposed absorber-related indexes. By studying the high absorption band of the absorber, the selectivity can be better investigated in depth. Here, 200-4000 nm is chosed as the depth study band. The absorber possesses an ultra-wide bandwidth of 3554 nm and an average absorption of over 97.4%, and in the 200-3754 nm band, the absorber has an ultra-high absorption rate of more than 98.3%, and its thermal emitter has a high emission efficiency of 94% at a temperature of 1000 K. Notably, the weighted average absorption in the 280-4000 nm band at AM1.5 is as high as 98.86%, with a loss of only 1.14%. The ultra-broadband absorption property of this solar absorber is mainly a joint effect of surface plasmon resonance coupling. An ultra-wideband solar selective absorber and highly efficient thermal emitter has been designed. The emissivity of this absorber is below 20% in all far-infrared bands beyond 6000 nm. The weighted-average absorption efficiency is 98.86%, with a loss of solar energy of only 1.14%. The structure has a thermal emission efficiency of 94% at 1000 K.image (c) 2023 WILEY-VCH GmbH