Graphene-TiN-Fe2O3-W metasurface solar absorber: A computationally optimized ultra-broadband design for scalable solar-thermal and renewable energy applications

Abstract

The urgent demand for efficient renewable energy solutions has accelerated progress in solar absorber technologies; however, many existing designs remain constrained by limited spectral bandwidth, angular sensitivity, and fabrication complexity. This study introduces a multi-material metasurface solar absorber that achieves an unprecedented ultra-broadband operation spanning 0.20-3.00 mu m (bandwidth approximate to 3000 nm) with exceptional angular tolerance up to 80 degrees. The proposed architecture integrates a titanium nitride (TiN)-coated square resonator, ferric oxide (Fe2O3) dual circular rings, and tungsten (W)/yttrium aluminum garnet (Y3Al5O12) cylindrical resonators on a graphene-enabled tunable metasurface, supported by silicon dioxide and silicon nitride substrates. This material hybridization enables absorption efficiencies exceeding 99.9 % across wide incidence angles while preserving fabrication feasibility. To further enhance the performance, machine learning based optimization using an XGBoost algorithm is employed for multi-objective design exploration, achieving high predictive accuracy (R2 = 0.9743) in modeling angular response. Electromagnetic simulations confirm that the absorber's superior performance arises from synergistic plasmonic-dielectric hybridization, which excites multiple resonant modes to broaden the spectrum. Comparative benchmarking against existing solar absorbers highlights the proposed design's superiority in both bandwidth and angular robustness. By integrating advanced materials engineering, electromagnetic optimization and machine learning driven design strategies, this work develops a new platform for next-generation solar energy harvesting. Furthermore, the reliability and scalability of the proposed absorber make it suitable for deployment in diverse solar thermal applications including industrial process heating, domestic water heating, agricultural crop drying and residential space heating systems.