Researchers at the Rensselaer Polytechnic Institute have developed white light emitting diodes (or LEDs) with better luminous efficiency without consuming more energy.
Many LEDs on the market 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 scientists have thus made it possible to achieve, under low current, a luminous efficiency greater than 80 lumens per watt (lm / W), compared to 60 lm / W for a lamp. fluorescence and 14 lm / W with a conventional incandescent lamp.
The so-called solid state (SSL) lighting industry, which groups together applications
(signage, urban lighting, etc.), has set itself a target of 150 lm / W by 2012. The US Department of Energy (DOE) considers that the generalization of LEDs, recognized for their safety, 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 of the DOE and the National Energy Technology Laboratory.
USAT 14 / 04 / 05
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