Overcoming non-radiative losses with AlGaAs PIN junctions for near-field thermophotonic energy harvesting

TL;DR

This paper demonstrates that near-field coupling in AlGaAs PIN junctions significantly enhances thermophotonic energy harvesting efficiency by reducing non-radiative losses and increasing radiative heat transfer, enabling practical low-grade energy applications.

Contribution

It introduces an optimized AlGaAs PIN LED and GaAs PIN PV device design that leverages near-field effects to improve energy harvesting performance and reduce non-radiative recombination losses.

Findings

Power output reaches 2.2 W/cm² at 10 nm gap for 600 K LED

Near-field coupling enhances radiative heat transfer via wave tunnelling

Non-radiative recombination rates are lower than radiative ones in the near field

Abstract

In a thermophotonic device used in an energy-harvesting configuration, a hot light-emitting diode (LED) is coupled to a photovoltaic (PV) cell by means of electroluminescent radiation in order to produce electrical power. Using fluctuational electrodynamics and the drift-diffusion equations, we optimise a device made of an AlGaAs PIN LED and a GaAs PIN PV cell with matched bandgaps. We find that the LED can work as an efficient heat pump only in the near field, where radiative heat transfer is increased by wave tunnelling. A key reason is that non-radiative recombination rates are reduced compared to radiative ones in this regime. At 10 nm gap distance and for 100 cm.s --1 effective surface recombination velocity, the power output can reach 2.2 W.cm --2 for a 600 K LED, which highlights the potential for low-grade energy harvesting.