Building a better light bulb

February 1, 2012, American Institute of Physics

Scientists study the movement of charge carriers to design an organic LED that is energy efficient and still casts a warm, natural glow.

Incandescent light bulbs are energy hogs, but many people prefer them for the cozy quality of light they emit. Scientists from Dresden University of Technology in Germany have set out to build energy efficient organic LED (OLED) lights that could rival in white-light color quality.

OLEDs consist of many layers of organic materials with different electrical properties. Excited electrons move through the materials and when the electrons are reunited with positive "holes," they emit electromagnetic radiation in the form of visible light.

To build their white light OLED, the researchers used four separate emitter layers: blue, green, yellow, and red. The different colors are combined to cover all parts of the visible spectrum. Through a detailed study of the movement of electrons through the OLED, the scientists were able to tune the color and quality of the light by adjusting the height of the layers.

The final OLED, described in the AIP's , casts a color of light very near to warm white point A, a standard measure of the white reached by some incandescent bulbs. The OLED also has high color stability, meaning the light can be dimmed without noticeably altering its quality.

Explore further: High-brightness breakthrough

More information: "Organic LEDs for Lighting: High Color Quality by Controlling Energy Transfer Processes in Host-Guest-Sytems" is accepted for publication in the Journal of Applied Physics.

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not rated yet Feb 02, 2012
Wrong application for a very interesting technology!
OLED are not and will not be the optimal solution for bulbs.
They are much better suitable for other lighting applications.
Light quality and efficiency and also durability may be on par with LEDs in the future (10 years?), but OLEDs need an area of several (hundreds) cm2 to emit a defined amount of light, whereas LEDs just need a few mm2 for the same amount of light.
not rated yet Feb 02, 2012
The character of light may serve as an advantage of OLED's over LED or even light bulbs in some applications, where dispersed source of light is required. The bigger problem is, the OLED's production will consume a high amount of rare indium, so that the problem of transparent electrodes must be solved too. The life-time and stability of OLED's isn't good enough too.
not rated yet Feb 02, 2012
BASF and Phillips doing it right and announce a "practical breakthrough"

sorry german link:
not rated yet Feb 02, 2012
BASF and Phillips doing it right and announce a "practical breakthrough"

Why not, but I did see the same illustration before three years already... http://www.gizig....nte.html

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