Plasmon-enhanced thermoelectric performance in multiresonant bowtie cross nanoantenna arrays

Abstract. Efficient conversion of mid-infrared (MIR) radiation into electricity remains a challenge for thermoelectric devices. We present multiresonant Ag–Si:B–Ni bowtie cross nanoantenna (BCN) arrays that exploit plasmon-enhanced photothermal effects to achieve broadband MIR absorption and voltage generation via the Seebeck effect. The 9×9 BCN arrays, fabricated by electron beam lithography, exhibit multiple plasmonic resonances from 18 to 48 THz with a ∼30  THz bandwidth. COMSOL simulations reveal strong field confinement and open-circuit voltages up to 11.19  μV under 1000  W·m2 illumination, which are experimentally validated by Fourier Transform Infrared measurements. The broadband response, geometry-dependent tunability, and efficient heat-to-electric conversion establish BCNs as promising candidates for waste-heat harvesting, MIR sensing, and plasmonic metasurface thermoelectrics.