Irreversible Thermodynamic Bound for the Efficiency of Light-Emitting Diodes

Abstract

A thermodynamic model for light-emitting diodes (LEDs) is developed by considering energy and entropy flows in the system. Thermodynamic constraints have previously been considered separately for the reversible process of electroluminescence in LEDs and for light extraction and collimation in other optical systems. By considering both processes in the LED model, an irreversible upper bound for the conversion of electrical energy to optical energy is derived and shown to be higher than unity, but tighter and more realistic than the reversible case. We also model a LED as an endoreversible heat engine where the carrier-transport processes can be directly connected to the elements of a thermodynamic cycle.

Influence of photo-generated carriers on current spreading in double diode structures for electroluminescent cooling

“…Fundamentally, EL cooling is based on simple thermodynamics of light 5 emitting diodes (LEDs), allowing a diode to emit a photon with an energy larger than the bandgap of the semiconductor material the LED is made of. This applies even when the bias voltage of the LED is arbitrarily small [3][4][5].…”

Photovoltatronics: intelligent PV-based devices for energy and information applications

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Nonequilibrium Theory of the Conversion Efficiency Limit of Solar Cells Including Thermalization and Extraction of Carriers

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