2013年8月31日星期六

LED Lighting Proved: Why LED efficiency drops at high current

LED Lighting Proved: Why LED efficiency drops at high current

2013/08/30

04sep13RensselaerResearchers at the US Rensselaer Polytechnic have proven a link between LED efficiency drop at high current and carrier mobility. Better lighting LEDs could result.

“Efficiency droop, first reported in 1999, has been a key obstacle in the development of LED lighting for situations, like household lighting, that call for economical sources of versatile and bright light,” said the university.

Published in Applied Physics Letters, the work shows that at high current an electric field develops within the p-type region of the diode allowing electrons to escape the active region where they would otherwise re-combine with holes to emit photons – a mechanism previously proposed, but not proven, said Rensselaer.

“We measure excellent correlation between the onset of field build-up and the onset of droop. This is clear evidence that the mechanism is electron leakage, and we can describe it quantitatively,” said Rensselaer researcher David Meyaard. “For example, in one result reported in the paper, we show the onset of high injection and the onset of droop and you can see that they are very nicely correlated. And that was just not possible in the past because there was really no theoretical model that described how electron leakage really works.”

“If the holes and the electrons had similar properties, there is a symmetry; both would meet in the middle, where the quantum well is, and there they recombine,” said Professor Fred Schubert. “What we have instead is a material system where the electrons are much more mobile than the holes. And because they are very mobile, they diffuse more easily, they also react more easily to an electric field. Because of that asymmetry, or disparity, we have a propensity of the electrons to shoot over and to be extracted from the quantum well. And so they don’t meet the hole in the active region and so they don’t emit light.”

Based on the theoretical model, Meyaard and Schubert will look for LED structures that reduce the issue.

The paper is ‘Identifying the cause of the efficiency droop in GaInN light-emitting diodes by correlating the onset of high injection with the onset of the efficiency droop.’


Welcome to SUV System Ltd!

SUV System Ltd is ISO 90012008 Certified electronics distributor with 10 years of experiences.

We have built up long term business relationship with about many companies which are stockers and authorized agents. we have a steady and reliable supply to meet customer's demands to the greatest extent .Confidently, we are able to lower your cost and support your business with our years of professional service.

SUV System Ltd is Electronic Components Distributor Supplies,Find Quality Electronic Components Supplies Products IC(Integrated Circuits),Connectors,Capacitor,Resistors,Diodes,Transistors,LED at Suvsystem.com. Sourcing Other Energy, Environment, Excess Inventory Products from Manufacturers and Suppliers at Suvsystem.com

Electronic Components distributor:http://www.suvsystem.com

Connectors Distributor:http://www.suvsystem.com/l/Connectors-1.html

IC Distributor:http://www.suvsystem.com/l/IC(Integrated-Circuits)-1.html

LED Distributor:http://www.suvsystem.com/l/LED-1.html

Capacitor Distributor:http://www.suvsystem.com/l/Capacitor-1.html

Transistor Distributor:http://www.suvsystem.com/l/Transistors-1.html

Resistor Distributor:http://www.suvsystem.com/l/Resistors-1.html

Diode Distributor:http://www.suvsystem.com/l/Diodes-1.html

SUV System Ltd insists on the managing faith ofsincereness,speciality,foresight, win-win,so we build up stable-relationship customers located all over the world, including the States, Europe, Argentina, UAE, Malaysia, Australia,and India etc

we are focus on the following fields,and hope we can help you.


Ligitek LED Digital Transistors chip Filter saws Fleld Effect Transistors Thin Film Resistors Rectifier Diodes Industrial IC Fast Recovery Diodes Bipolar Transistors AVX Resistors NXP Transistors Diodes Inc PANASONIC Resistors MURATA IC HARRIS IC Metal Can Packages Transistors Voltage Regulators Transistors Texas Instruments(TI) IC TOSHIBA Diodes Switching Diodes Military IC NS IC Chip Inductors INTERSIL IC Resistor Arrays Cypress IC ST Transistors Kingbrigt LED Renesas parts IC Transistors ROHM Resistors Other Parts ON Diodes Chip Fuses Resistor Networks Resistors Atmel IC MOTOROLA IC Transistors Freescale AD IC
http://www.suvsystem.com/a/5412.aspx