Much current display research is aimed at so-called organic light emitting diodes or OLEDs. These have several big advantages that promise to revolutionize the displays you’ll be watching ten years from now. They’re bright while being very energy efficient, making them a natural improvement for laptop computer screen use as well new screens for smaller gizmos like cellphones. Unlike current rigid silicon-based LCD displays that have to be expensively manufactured as an electronics device in a vacuum chamber, carbon-based OLEDs can be naturally integrated into plastics via processes like offset printing and inkjet printing. This ease of manufacture promises to produce displays that are flexible, cheap and can be easily rolled out like wallpaper to create a monitor of any size, anywhere. Thus a visual version of the Star Trek holodeck retrofitted into your living room as a home improvement is on the way.
But for all these improvements, OLED displays were envisioned to need the same red-green-blue dot system we have always used – until now. Graduate student Steve Welter was testing some OELD samples containing an additive known as dinuclear ruthenium. Hook the sample up to a battery, it glowed red – no surprise. Reverse the wires on the battery terminals, it glowed green – huge surprise. The notion that one diode could produce two colors was so alien that Welter’s boss, Dr. J. W. Hofstraat and his colleagues did not at first accept the student’s report. “We had to see it ourselves, let me put it that way,” Dr. Hofstraat said. Notes Dr. George Malliaras of Cornell University, “This is very exciting. These are the best discoveries: a student does something and discovers a new physical phenomena. It simply shows that although there has been a lot of research in the field of organic light-emitting devices, there are still issues that are not fully understood.”
Now the search is on for other OLED additives that could produce red, green AND blue from the same sample, depending on the direction of current and voltage. This now seems possible, and if found, would revolutionize, simplify and drastically cheapen OLED screens by allowing the use only one set of dot control circuitry instead of the current three now needed for all other display types. Perhaps you’ll one day tell your grandkids you remember when three color dots were needed to show a pixel of color on one of those old eye-straining screens, just as your own grandparents tell of remebering when radios had vaccuum tubes.