Demonstration of Thermoradiative Energy Conversion with InAs Cells

Thermoradiative diodes are devices that convert thermal energy to electricity while emitting light as waste heat to their surroundings. These are similar to solar- and thermo-photovoltaics in many ways, but they operate with a net emission of light instead of a net absorption. Despite only being recently proposed, thermoradiative converters have gained substantial interest for their potential to achieve high efficiency energy conversion with low heat source temperatures, but there have been very few experimental investigations. Here, we design, fabricate, and demonstrate a large-area (0.8 cm2) InAsP / InAs / InAsP double heterojunction device for thermoradiative energy conversion at elevated temperatures of several hundred degrees Celsius. The cell achieves a record-low reverse saturation current for InAs below 15 mA/cm2 at 25 °C via minority carrier extraction, which minimizes nonradiative Auger losses. The device generates electricity with power densities >0.4 mW/m2 and short-circuit currents on the order of milliAmps, resulting in the first demonstration of measurable power from a thermoradiative device at elevated temperatures. Our results show that pathways exist to practical thermoradiative converters through careful device design.