Efficiency of Negative-Illumination Photovoltaic Energy Conversion

Infrared diodes have the potential to generate electricity by harnessing thermal radiation. This mechanism offers a promising route for harvesting energy from Earth’s ambient heat through infrared emission. However, its practical application has long been limited by extremely low energy conversion efficiency. In this paper, we systematically investigate both the energy conversion efficiency and external quantum efficiency of infrared diodes when oriented toward a sufficiently cold surface. Our measurements reveal that the external quantum efficiency can reach up to 60% under optimal diode temperature conditions. In contrast, the energy conversion efficiency remains below 10–3%, highlighting a significant gap between photon conversion and useable electrical power. Furthermore, our theoretical analysis suggests viable strategies for significantly improving power generation. These insights create avenues for advancing thermoradiative energy harvesting technologies and overcoming current efficiency limitations.