LONDON Novaled AG (Dresden, Germany) and Eastman Kodak Co. (Rochester, NY) have developed white PIN OLEDs for use in active-matrix OLED displays.
The joint development, presented at the Society for Information Display conference earlier this month, is based on Novaled's p- and n-type doped transport layers and Eastman Kodak's fluorescent emitter systems. Single unit and tandem white OLEDs for potential use in RGBW OLED displays were presented.
For the single unit devices, 15.8-cd/A with a lifetime of 30,000 hours and color coordinates of 0.32/0.35 at 1,000 candelas per square meter were reached. Display simulations based on the power life model of Eastman Kodak showed, that this formulation is suitable for use in RGBW displays, Novaled said.
In the tandem device approach a current efficiency of 33.2 cd/A at color coordinates 0.28/0.31 was achieved. The lifetime of the device was 77,000 hours compared to 51,000 hours that were reached with devices based on conventional Li-doping for the connector unit. This improvement can be mainly attributed to the better stability of the molecular doping in such connector unit systems.
In a display simulation the tandem device compares favorably with a conventional tandem device based on Li-doped p-n connectors; allowing display lifetime to be improved from 38,000 to 53,000 hours.
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