Thermophotovoltaic Efficiency of 40%

TL;DR

This paper reports record-high thermophotovoltaic (TPV) cell efficiencies exceeding 40%, achieved through advanced tandem cell design and spectral filtering, promising significant improvements for renewable energy and grid decarbonization.

Contribution

First experimental demonstration of high-bandgap tandem TPV cells reaching over 40% efficiency with optimized spectral filtering and high emitter temperatures.

Findings

Achieved 41.1% efficiency with a 1.4/1.2 eV tandem cell.

Achieved 39.3% efficiency with a 1.2/1.0 eV tandem cell.

Demonstrated potential for TPV systems in renewable energy and decarbonization.

Abstract

We report the fabrication and measurement of thermophotovoltaic (TPV) cells with efficiencies of >40%, which is a record high TPV efficiency and the first experimental demonstration of the efficiency of high-bandgap tandem TPV cells. TPV efficiency was determined by simultaneous measurement of electric power output and heat dissipation from the device via calorimetry. The TPV cells are two-junction devices comprising high-quality III-V materials with band gaps between 1.0 and 1.4 eV that are optimized for high emitter temperatures of 1900-2400{\deg}C. The cells exploit the concept of band-edge spectral filtering to obtain high efficiency, using high-reflectivity back surface reflectors to reject unusable sub-bandgap radiation back to the emitter. A 1.4/1.2 eV device reached a maximum efficiency of (41.1 +/- 1)% operating at a power density of 2.39 W/cm2 under an irradiance of 30.4 W/cm2 and emitter temperature of 2400{\deg}C. A 1.2/1.0 device reached a maximum efficiency of (39.3 +/- 1)% operating at a power density of 1.8 W/cm2 under an irradiance of 20.1 W/cm2 and emitter temperature of 2127{\deg}C. These cells can be integrated into a TPV system for thermal energy grid storage (TEGS) to enable dispatchable renewable energy. These new TPV cells enable a pathway for TEGS to reach sufficiently high efficiency and sufficiently low cost to enable full decarbonization of the grid. Furthermore, the high demonstrated efficiency also gives TPV the potential to compete with turbine-based heat engines for large-scale power production with respect to both cost and performance, thereby enabling possible usage in natural gas or hydrogen-fueled electricity production.