GaAs-based near-field thermophotonic devices: Approaching the idealized case with one-dimensional PN junctions

Abstract

Thermophotonics (TPX) is a technology close to thermophotovoltaics (TPV), where a heated light-emitting diode (LED) is used as the active thermal emitter of the system. It allows to tune the heat flux, by means of electroluminescence, to a spectral range matching better the gap of a photovoltaic cell. The concept is extended to near-field thermophotonics (NF-TPX), where enhanced energy conversion is due to both electric control and wave tunnelling. We perform a thorough numerical analysis of a GaAs-based NF-TPX device, by coupling a near-field radiative heat transfer solver based on fluctuational electrodynamics with an algorithm based on a simplified version of the drift–diffusion equations in 1D. This allows for the investigation of the emission and absorption profiles in the LED and the photovoltaic (PV) cell, and for the scrutiny of the impact of key parameters. We also demonstrate that the performance obtained with this algorithm can approach idealized cases for improved devices. For the considered simplified architecture and 300 K temperature difference, we find a power density output of 1 W cm − 2 , underlining the potential for waste heat harvesting close to ambient temperature. • Near-field thermophotonics allows waste-heat harvesting of moderate temperatures. • GaAs is a promising material for the thermophotonic elements: LED and photovoltaic cell. • Thorough modelling of the 1D pn junction architecture is performed. • About 35 W m −2 K −1 can be produced if radiative recombinations are limited.