Electronic Design

OLED Origins

Believe it or not, OLEDs extend back to the early 1950s. Researchers at the Université de Nancy in France produced electroluminescence in organic materials by applying a high-voltage ac potential to crystalline thin films of acridine orange and quinacrine. Dow Chemical Co. followed in the 1960s by developing ac-driven electroluminescent cells using doped anthracene. Other researchers added further contributions.

It’s generally acknowledged that the Kodak Company was the first to discover the diode OLED in the late 1970s, when it was observed that organic materials can glow in response to electrical currents. Kodak scientist Ching Tang then discovered that sending an electrical current through a carbon compound caused the compound to glow. Both Tang and StevenVan Slyke continued the research, and in 1987, they reported on OLED materials that became the foundation of today’s OLED technology.

Since then, Kodak has set industry benchmarks with patented discoveries in OLED technology. Third-generation OLEDs from Kodak and others have been demonstrated as vibrant full-color displays that far exceed the color gamut of the other leading display technology, LCDs, by as much as 20%.

In the last few years, OLED advances have come fast and furious. For instance, Cambridge Display Technology (CDT) pioneered the development of light-emitting polymers (P-OLEDs) and their use in a wide range of electronic display products used for information management, communications, and entertainment. P-OLEDs are part of the family of OLEDs—thin, lightweight, and power-efficient devices that emit light when an electric current flows.

Another OLED contribution from CDT is its development of light-emitting blue polymers with lifetimes of 25,000 hours from an initial luminance of 400 cd/m2, which is equivalent to 400,000 hours from 10 cd/ m2. This milestone further enhances the company’s polymer P-OLEDs, since the production of video-capable OLED displays requires a full range of red, green, and blue colors with long lifetimes and good efficiency.

Other major OLED manufacturers like Universal Display Corp. and Novaled GmbH have reported OLED advances in terms of light output levels and better efficiencies. Dupont Co. is also a leading contributor to OLED materials and process technologies. Osram Opto Semiconductors and Siemens are investigating OLEDs as well.

Japanese companies like Sony and Matsushita and Korea’s Samsung have become extremely intrigued with the use of OLEDs for consumer electronic products. Many prototypes of such products have emerged, and there are plans to mass-produce them, though it remains unclear when this will happen.

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