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Mechanically stacked, tandem thermophotovoltaic (TPV) cells featuring integrated air-bridge InGaAs and InGaAsP subcells achieve high spectral efficiency and emission temperature versatility. Thermocompression bonding of electrodes on opposing single air-bridge cells increases out-of-band reflectance (ROUT) compared to cells lacking air bridges. We report a 0.74/0.74 eV homotandem exhibiting ROUT = 96.4%. When operated in a multiterminal arrangement, the homotandem achieves 38% efficiency, marking a 20% absolute improvement over a comparable two-terminal configuration. We also demonstrate a 0.9/0.74 eV heterotandem with ROUT = 97.2% and spectral efficiency approaching 80%. By minimizing losses associated with parasitic absorption and current mismatch, the tandem substantially expands the emission temperature range while preserving high efficiency. This leads to a reduction in the cost of energy storage by over 40%. The air-bridge tandem technology paves the way for high-performance tandem cells compatible with a variety of heat sources unrestricted by the choice of subcell materials.
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This content will become publicly available on May 22, 2025
High-efficiency air-bridge thermophotovoltaic cells
Thermophotovoltaic (TPV) cells generate electricity by converting infrared radiation emitted by a hot thermal source. Air-bridge TPVs have demonstrated enhanced power conversion efficiencies by recuperating a large amount of power carried by below-bandgap (out-of-band) photons. Here, we demonstrate single-junction InGaAs(P) air-bridge TPVs that exhibit up to 44% efficiency under 1435°C blackbody illumination. The air-bridge design leads to near-unity reflectance (97-99%) of out-of-band photons for ternary and quaternary TPVs whose bandgaps range from 0.74 to 1.1 eV. These results suggest the applicability of the air-bridge cells to a range of semiconductor systems suitable for electricity generation from thermal sources found in both consumer and industrial applications, including thermal batteries.
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- PAR ID:
- 10508892
- Publisher / Repository:
- Elsevier
- Date Published:
- Journal Name:
- Joule
- ISSN:
- 2542-4351
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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