Lighting the Future | Green Energy News

November 20, 2005 – Vol.10 No.35

LIGHTING THE FUTURE.

In part, the development of LED lighting has been focused on creating replacements for standard light bulbs: making an LED light bulb that looks and acts like a conventional incandescent bulb, fits in the same socket, and puts out the same amount of light.

(The development of compact fluorescent bulbs took the same route: make it look like a conventional bulb and maybe consumers will buy it with its initial higher cost, but with long term energy savings)

Perhaps a better route for LED lighting development is to ignore convention and design new types of lighting and light fixtures that look nothing like anything we’ve seen before: large area light tiles for instance.

With a $4.65 million grant from the U.S. Department of Energy (DOE) Osram Opto Semiconductors has pushed the concept of white-light LED light tiles a few steps closer to reality.

The first milestone was to develop a breakthrough 25 lumens per watt (lm/w) polymer-OLED (Organic Light Emitting Diode) device - a high-efficiency all-plastic light emitter if you will. OSRAM achieved white light by combining the OLED with an external phosphorescent polymer layer.

(OLEDs, by the way, could be more efficient than LEDs (which themselves use a fraction of the energy of incandescent bulb) and potentially be as inexpensive to produce as the more than a century old conventional light-bulb.)

The more exciting OSRAM OS breakthrough was to develop the first printed, color-tunable light source.

Consider this: the white light emitted from your computer screen comes from a combination of red, green and blue light as well as the absence of light, black.

Then consider that color ink jet printers will make a white-appearing color from Cyan (mostly blue), Magenta (reddish-blue), Yellow and Black, together better known as CMYK.

Now, roughly speaking, combine these two technologies - one that can emit white, or any color light, and one that can print in almost any color (including white). Add the two concepts together with OLED technology and you have a light source that is, in part, printable and is color tunable - any shade of color the lighting designer chooses.

OSRAM OS used printable polymer inks emitting the red, green and blue spectrum in an inkjet printer to create small patterns that would create colors. A wide range of emitted color can be chosen, from dark blue to white and the technology is, of course, scalable dependent on the size of the printing equipment. The goal, seemingly, is to make OLEDs that are printable.

For now the work of OSRAM OS is for demonstration purposes only: no word of commercialization has been mentioned.

The funding came from DOE’s Building Technologies program which aims to develop solid-state lighting that can accurately produce full sunlight spectrum at a product-system efficiency of 50 percent that is both cost competitive with conventional lighting and longer lasting. Visit OSRAM OS at http://www.osram-os.com/ .