Enhanced Absorption in Thin-Film Silicon Solar Cells Using a Broadband Plasmonic Nanostructure

Abstract: The design and fabrication of a metal-dielectric-metal absorber that achieves strong absorption from the ultraviolet (UV) to the near-infrared (near-IR) spectrum are presented. The proposed nanostructure consists of a periodic titanium (Ti) array as the top layer, a thin silicon dioxide (SiO2) spacer, and a continuous aluminum (Al) layer serving as the back reflector. Comprehensive optimization of structural parameters results in an average absorptance of 96% in the 280-1000 nm wavelength range. The proposed design exhibits polarization insensitivity and maintains high absorption efficiency under oblique incidence. Fabrication is carried out using electron beam lithography followed by a lift-off process, ensuring both high performance and manufacturing simplicity. Experimental measurements show strong agreement with numerical simulations, validating the effectiveness of the design. Furthermore, integration of the absorber into a thin-film silicon (Si) solar cell is analyzed, revealing significant enhancement in light absorption within the active layer. Owing to its broadband response, angular robustness, and structural simplicity, the proposed absorber shows strong potential for applications in solar energy harvesting, thermal emission, and advanced photovoltaic technologies.