Researchers at University of California, Santa Barbara, in collaboration with colleagues at CNRS-École Polytechnique in France, have conclusively identified Auger recombination as the mechanism that causes light emitting diodes (LEDs) to be less efficient at high drive currents.
Until now, scientists had only theorized the cause behind the phenomenon known as LED “droop”—a mysterious drop in the light produced when a higher current is applied. The cost per lumen of LEDs has held the technology back as a viable replacement for incandescent bulbs for all-purpose commercial and residential lighting.
This could all change now that the cause of LED efficiency droop has been explained, according to researchers.
Knowledge gained from this study is expected to result in new ways to design LEDs that will have significantly higher light emission efficiencies. LEDs have enormous potential for providing long-lived high quality efficient sources of lighting for residential and commercial applications. The U.S. Department of Energy recently estimated that the widespread replacement of incandescent and fluorescent lights by LEDs in the U.S. could save electricity equal to the total output of fifty 1GW power plants.
“Rising to this potential has been contingent upon solving the puzzle of LED efficiency droop,” commented Speck, professor of Materials and the Seoul Optodevice Chair in Solid State Lighting at UCSB. “These findings will enable us to design LEDs that minimize the non-radiative recombination and produce higher light output.”
A definitive measurement of Auger recombination in LEDs has now been accomplished by Speck, Weisbuch, and their research team.
The experiment used an LED with a specially prepared surface that permitted the researchers to directly measure the energy spectrum of electrons emitted from the LED. The results unambiguously showed a signature of energetic electrons produced by the Auger process.
This story is reprinted from material from UC Santa Barbara, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.