Researchers at the Rensselaer Polytechnic Institute have developed white light emitting diodes (or LEDs) with better light efficiency without consuming more energy.
Many LEDs sold today combine semiconductor components with monochromatic radiation with phosphor emitting photons of a complementary color (which makes it possible to obtain visible white light).
However, more than half of the photons emitted by phosphorus are reabsorbed by the LED, decreasing the amount of light generated. By playing on the distance between the phosphor and the semiconductor as well as on the geometry of the lens of the LEDs, Nadarajah Narendran and her colleagues managed to release the photons usually absorbed.
The prototypes of SPE diodes (for Scattered Photon Extration) developed by the scientists thus made it possible to achieve, under low current, a luminous efficiency greater than 80 lumens per watt (lm / W), against 60 lm / W for a lamp fluorescent and 14 lm / W with a conventional incandescent lamp.
The solid state (SSL) lighting industry, which groups applications
various (signaling, urban lighting, etc.), has set a target of 150 lm / W by 2012. The United States Department of Energy (DOE) estimates that the generalization of LEDs, recognized for their security, resistance and efficiency could reduce national energy consumption by 29% by 2025. This work, published on the website of the journal Physica Status Solidi (a), was funded by the Building Technologies Lighting R&D Program from the DOE and the National Energy Technology Laboratory.
USAT 14 / 04 / 05
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