The efficiency challenge of nitride light-emitting diodes for lighting

• Published in: Physica status solidi. A, Applications and materials science Vol. 212; no. 5; pp. 899 - 913
• Main Authors: Weisbuch, Claude, Piccardo, Marco, Martinelli, Lucio, Iveland, Justin, Peretti, Jacques, Speck, James S.
• Format: Journal Article
• Language: English
• Published: Weinheim Blackwell Publishing Ltd 01.05.2015; Wiley Subscription Services, Inc
• Subjects: Carbon; Cost engineering; Efficiency; efficiency droop; energy efficiency; GaN; Illumination; Light emission; Light emitting diodes; Lighting; Lumens; nitride semiconductors; Reduction; solid-state lighting
• ISSN: 1862-6300; 1862-6319
• DOI: 10.1002/pssa.201431868

We discuss the challenges of light‐emitting diodes in view of their application to solid‐state lighting. The requirement is to at least displace the quite efficient fluorescent, sodium, and high intensity discharge lamps used today in the main energy consuming lighting sectors, industrial, commercial and outdoors, with more efficient and better light quality lamps. We show that both from the point of view of cost of ownership and carbon emissions reduction, the relevant metric is efficiency, more than the cost of lumens. Then, progress from present performance requires identification of the loss mechanisms in light emission from LEDs, and solutions competing with mainstream c‐plane LEDS grown on sapphire need to be on par with these. Special attention is devoted to a discussion of the efficiency droop mechanisms, and of a recent direct measurement of Auger generated electrons which appear to be responsible for droop. The authors discuss the challenges of light emitting diodes in view of their application to solid‐state lighting. They show that in view of the cost of ownership and of carbon emission reduction, the relevant metrics is efficiency (lumens/watts), more than the cost of lumens (lumens/$). Then, progress from present performance requires identification of the loss mechanisms in light emission from LEDs. This requires the analysis of both electronic and photonic processes in LEDs.