2024/12/13 by Mathieu Giroux, Giroux, Mathieu, Sean Molesky +5 · 1 citation
Engineering · Physics and Astronomy · #Thermal Radiation and Cooling Technologies #Quantum Electrodynamics and Casimir Effect #Advanced Thermodynamic Systems and Engines
paper · pdf · doi:10.48550/arxiv.2412.10217
Near-field thermophotovoltaics (NFTPV) systems have significant potential for\nwaste heat recovery applications, with both high theoretical efficiency and\npower density, up to 40% and 11 mathrmW/cm2 at 900 K. Yet\nexperimental demonstrations have only achieved up to 14% efficiency and modest\npower densities (i.e., 0.75 mathrmW/cm2). While experiments have\nrecently started to focus on photovoltaic (PV) cells custom-made for NFTPV,\nmost work still relies on conventional doped silicon radiators. In this work,\nwe design an optimized NFTPV radiator for an indium arsenide-based system and,\nin the process, investigate models for the permittivity of InAs in the context\nof NFTPV. Based on existing measurements of InAs absorption, we find that the\ntraditional Drude model overestimates free carrier absorption in InAs. We\nreplace the Drude portion of the InAs dielectric function with a revised model\nderived from ionized impurity scattering. Using this revised model, we maximize\nthe spectral efficiency and power density of a NFTPV system by optimizing the\nspectral coupling between a radiator and an InAs PV cell. We find that when the\nradiator and the PV cell are both made of InAs, a nearly threefold improvement\nof spectral efficiency is possible compared to a traditional silicon radiator\nwith the same InAs cell. This enhancement reduces subgap thermal transfer while\nmaintaining power output.\n