Ultra-wideband and thermally stable absorber for advanced solar energy harvesting applications

The rising demand for efficient solar energy harvesting has focused attention on absorbers that operate across wide frequency ranges with stable performance, yet most conventional designs remain limited by narrow bandwidth, polarization dependence, angular sensitivity and complex fabrication, restricting their large-scale use in solar-thermal and thermophotovoltaic systems. To overcome these challenges, we propose a metasurface absorber configured in a metal-dielectric-metal architecture. The design achieves absorption greater than 90 % within 149.25–1948.47 THz (wavelengths 154–2010 nm) with an average efficiency of 95.54 % and maintains absorption above 80 % from 102.59 THz to beyond 2500 THz. Under AM-1.5 solar spectrum conditions, the device shows a solar absorption efficiency of 97.38 %, while its thermal emission performance closely follows that of an ideal blackbody, rising from 76.73 % at 500 K to 95.01 % at 3500 K. In addition, the absorber shows excellent solar-to-electrical conversion efficiency, reaching a maximum of 66.49 % under high solar concentration at 1000 K. The proposed design also proves to be polarization-insensitive and angularly stable maintaining more than 80 % absorption for incidence angles up to 60° in both TE and TM modes. By uniting ultra-broadband operation, thermal resilience, angular stability and fabrication compatibility, the proposed absorber provides a highly effective pathway toward advanced solar energy harvesting and photothermal conversion technologies.