Fundamental mechanisms of electroluminescence refrigeration in heterostructure light-emitting diodes

Abstract

The fundamental mechanisms of electroluminescence (EL) refrigeration in heterostructure light emitting diodes, is examined via carrier energy loss (and gain) during transport, relaxation, and recombination, where the contribution of electrons and holes are treated separately. This analysis shows that the EL refrigeration process is a combination of thermoelectric cooling that mainly occurs near the metal/semiconductor contacts and radiative recombination which mainly occurs in the active region. In semiconductors such as GaAs, electrons and holes make different contributions to the refrigeration processes as a result of their different densities of states.

Electro-luminescent cooling: light emitting diodes above unity efficiency

“…In 1959 a US Patent was granted for a refrigeration device based on the principle [24]. In the last decade, the applied literature on the subject has expanded to include more realistic modeling and more recent advances in device fabrication technologies [1,2,3,4,5,6,7] and at least one attempt to demonstrate practical cooling is currently underway [8]. Nevertheless, prior to this work, the basic phenomenon of electrically-driven light emission above unity efficiency had never been experimentally verified.…”

“…It has long been known that in theory a light-emitting diode (LED) may emit optical power in excess of the electrical power required to drive it, with the remainder drawn from lattice heat. This phenomenon has been referred to in the literature by various authors as electro-luminescent cooling [1,2], electroluminescence refrigeration [3,4], opto-thermionic cooling [5,6], the operation of a "Thermischer Konverter" [7], and thermo-photonic cooling [8].…”

Light-emitting diodes operating above unity efficiency for infrared absorption spectroscopy

“…Theoretical results from the past few years have suggested that modern epitaxial growth and fabrication methods may enable practical devices for thermal energy conversion [6], [7], [8], [9], [10].…”

Electro-luminescent cooling in the deep sub-bandgap bias regime

“…Apart from the work of the author and his direct collaborators, two recent experimental e↵orts have been documented, one at Arizona State University and the other at Aalto University in Finland. In parallel with basic theoretical work on the role of heterostructures [14] and low-dimensional systems [15] in the phenomenon, the group at Arizona State fabricated a microstructure [16,17] designed to produce a 6 C drop due to electro-luminescent cooling. Although the group's publications indicate that a substantial experimental e↵ort was made to realize cooling, net cooling has not been reported as of yet.…”