Polymer Innovation Key to True White LEDs

Physicists at the University of Utah have gotten us closer to having truly white organic light-emitting diodes (OLEDs), which would allow solar cells to convert sunlight to electricity more efficiently and improve computer memory.

The key to the innovation came when the scientists inserted platinum atoms into the molecular chain of a plastic-like polymer. Thepolymer diode platinum atoms gave the scientists the ability to “tune” the polymer so that it could emit light of different colors, according to a university press release.

“This polymer emits light in the blue and red spectral range, and can be tuned to cover the whole visible spectrum,” says University of Utah physicist Z. Valy Vardeny. “As such, it can serve as the active [or working] layer in white OLEDs that are predicted to replace regular light bulbs.”

Existing LEDs that emit white light work a bit differently from the ones developed by the Utah group. The press release explains further:

Certain existing white light bulbs use LEDs, or light-emitting diodes, and some phone displays use organic LEDs, or OLEDs. Neither are truly white LEDs, but instead use LEDs made of different materials that each emit adifferent color, then combine or convert those colors to create white light, Vardeny says.

The platinum metal atoms inserted into the chain-like polymer at certain intervals gave the scientists the ability to adjust or tune the colors emitted. Such an innovation is a step toward the creation of a true white OLED generated by multiple colors from a single polymer. The press release explains further the advantage:

Existing white OLED displays — like those in recent cell phones — use different organic polymers that emit different colors, which are arranged in pixels of red, green and blue and then combined to make white light, says Vardeny, a distinguished professor of physics. ‘This new polymer has all those colors simultaneously, so no need for small pixels and complicated engineering to create them.’

The Utah physicists’ polymers are not true OLEDs because they emit light when stimulated by other light. A true OLED is a polymer that emits light when it is stimulated by electrical current.

“We haven’t yet fabricated an OLED with it,” says Vardeny, whose research was summarized in a paper that was published in September in the journal Scientific Reports. “The paper shows we get multiple colors simultaneously from one polymer,” which will lead the way for the development of an OLED in which single pixels emit white light.

Within one year, Vardeny predicts, scientists will make a “platinum-rich pi-conjugated polymer” that is structured so that it can emit white light when stimulated by light. In two years, true white organic LEDs will be produced, Vardeny says.

Source: “Toward a Truly White Organic LED,” University of Utah, 9/13/13
Image by MrX.