Analysis of absorption and thermal radiation performance of solar absorbers based on TiN, Nb2O5 and graphene

•The absorption bandwidth for efficiency exceeding 90 % spans 2360 nm, while for efficiency surpassing 95 %, it covers 1819 nm.•At AM 1.5, the average absorption efficiency of the structure reaches 95.71 %.•The thermal radiation absorption efficiency is greater than 80 % in the range of 300–1400 K.•The structure exhibits insensitivity to changes in incident light angles, making it highly versatile for applications in solar energy harvesting and thermal radiation. This work proposes a multi-layer structured solar absorber based on TiN, metal oxide Nb2O5 and graphene. Simulations and calculations are based on finite-difference time-domain (FDTD) method. The average absorption efficiency of the structure is 94.41 % across the spectrum of 280–3000 nm, with absorption bandwidths of 2360 nm (for absorption efficiency exceeding 90 %) and 1819 nm (for absorption efficiency exceeding 95 %). Moreover, the weighted average absorption under AM 1.5 reaches 95.71 %, underscoring the exceptional absorption capabilities of the structure. This structure also has the property of polarization insensitivity. The absorption spectrum varies weakly with the polarization angle, and there is some deviation as the incident light increasing from 0 to 60°. However, the absorption efficiency at 60° is still 81.16 %. We further investigated the thermal radiation performance, discovering an efficiency exceeding 80 % within the range of 300–1400 K, and surpassing 90 % within 800–1400 K. These outstanding absorption and thermal radiation properties position the structure as highly versatile, with potential applications spanning solar energy harvesting and radiation-related fields. Based on TiN, Nb2O5 and graphene, this paper proposes a solar absorber with a CRRG structure. Differing from prior studies, we utilized graphene within the near-ultraviolet to near-infrared spectrum, yielding exceptional absorption outcomes. The average absorption efficiency of this structure in the 280–3000 nm wavelength range reaches 94.41 %, and the weighted average absorption at AM 1.5 is 95.71 %. Meanwhile, the absorption bandwidths of the structure are 2360 nm and 1819 nm, respectively. This indicates that the absorption performance of the structure is excellent, and through calculation, the structure has also achieved superior thermal radiation performance. The thermal radiation efficiency in the range of 300–1400 K is greater than 80 %, and the thermal radiation efficiency in the range of 800 K-1400 K is