Thermionic-enhanced near-field thermophotovoltaics for medium-grade heat sources

Datas Medina, Alejandro ORCID: and Vaillon, Rodolphe (2019). Thermionic-enhanced near-field thermophotovoltaics for medium-grade heat sources. "Applied Physics Letters", v. 114 (n. 13); pp. 1-5. ISSN 0003-6951.


Title: Thermionic-enhanced near-field thermophotovoltaics for medium-grade heat sources
Item Type: Article
Título de Revista/Publicación: Applied Physics Letters
Date: April 2019
ISSN: 0003-6951
Volume: 114
Freetext Keywords: Vacuum arcs; Solid-state devices; Solar cells; Thermophotovoltaics; Semiconductors; Thermionic emission
Faculty: E.T.S.I. Telecomunicación (UPM)
Department: Electrónica Física
Creative Commons Licenses: Recognition - No derivative works - Non commercial

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Conversion of medium-grade heat (temperature from 500 to 1000 K) into electricity is important in applications such as waste heat recovery or power generation in solar thermal and co-generation systems. At such temperatures, current solid-state devices lack either high conversion efficiency (thermoelectrics) or high-power density capacity (thermophotovoltaics and thermionics). Near-field thermophotovoltaics (nTPV) theoretically enables high-power density and conversion efficiency by exploiting the enhancement of thermal radiation between a hot emitter and a photovoltaic cell separated by nanometric vacuum gaps. However, significant improvements are possible only at very small gap distances (<100 nm) and when ohmic losses in the photovoltaic cell are negligible. Both requirements are very challenging for current device designs. In this work, we present a thermionic-enhanced near-field thermophotovoltaic (nTiPV) converter consisting of a thermionic emitter (graphite) and a narrow bandgap photovoltaic cell (InAs) coated with low-workfunction nanodiamond films. Thermionic emission through the vacuum gap electrically interconnects the emitter with the front side of the photovoltaic cell and generates an additional thermionic voltage. This avoids the use of metal grids at the front of the cell and virtually eliminates the ohmic losses, which are unavoidable in realistic nTPV devices. We show that nTiPV operating at 1000 K and with a realizable vacuum gap distance of 100 nm enables a 10.7-fold enhancement of electrical power (6.73 W/cm2) and a 2.8-fold enhancement of conversion efficiency (18%) in comparison with a realistic nTPV device having a series resistance of 10 mΩ·cm2.

Funding Projects

Horizon 2020
Next GenerAtion MateriAls and Solid State DevicEs for Ultra High Temperature Energy Storage and Conversion
Government of Spain

More information

Item ID: 64080
DC Identifier:
OAI Identifier:
DOI: 10.1063/1.5078602
Official URL:
Deposited by: Memoria Investigacion
Deposited on: 06 Dec 2020 10:08
Last Modified: 06 Dec 2020 10:08
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