Al2O3-Ti substrates integrated with nested L-shaped Ti resonant arms toward ultra-broadband solar absorption

To tackle the difficulties arising from the depletion of traditional energy sources, this paper designs and optimizes a novel solar absorber for clean energy applications, aiming to achieve high absorption rate, ultra-broadband response, and polarization insensitivity. The proposed absorber is composed of a titanium (Ti) substrate, an aluminum oxide (Al 2 O 3 ) dielectric layer, and four sets of nested L -shaped Ti resonant arms. FEM simulation results indicate that the absorber delivers superior performance in the 300 – 4000 nm range. Specifically, an average absorption rate of 98.91% is reached over a 3700 nm bandwidth, and the entire band exhibits a minimum absorption exceeding 90%. When exposed to AM1.5 standard illumination and high‑temperature conditions, the absorber shows excellent performance in both solar absorption and thermal radiation. Moreover, the absorber maintains stable high absorption performance over an incident angle range of 0° – 60° and a polarization angle range of 0° – 90°, showing good adaptability to operating conditions. These results indicate that the proposed design offers significant advantages in absorption performance and exhibits great potential for clean energy utilization.