Low-Voltage, High-Efficiency White Phosphorescent OLEDs for Lighting Applications (Phase II)

Investigating Organization
Universal Display Corporation

Principal Investigator(s)
Dr. Brian W. D'Andrade, bdandrade@universaldisplay.com, (609) 671-0980, x 292

Subcontractor
Princeton University, under the direction of Prof. Stephen R. Forrest

Funding Source
Small Business Innovation R&D, Phase II

Award
DOE Share: $750,000

Contract Period
8/1/05 - 8/1/06

The approach taken in this project is to combine novel low-voltage dopants, world record efficient phosphorescent OLED emission layers, and a stacked PHOLED architecture, to demonstrate a high-power efficiency >50 lm/W organic light source.

In Phase I, the goals were met and a white PHOLED, based on red, green, and blue phosphorescent emitters, was demonstrated to have a world record power efficiency of 20 lm/W at a luminance of 800 cd/m2.  This device was reported at the 2004 Society for Information Display conference in Seattle, Washington.  The overall excellent performance was accomplished without the use of outcoupling enhancement, so there remains significant potential to increase the power efficiency of low voltage PHOLEDs by a factor of more than 1.5.

In Phase II, UDC, Princeton University, and USC are further exploring new materials and device architectures that will be used by UDC in the fabrication of high-efficiency prototype lighting panels. The anticipated benefits of this work will be to demonstrate a new path for highly efficient white light sources by introducing a new dimension to the device design, such as high power, thereby significantly reducing the size of the substrate necessary for devices to produce optical power (>800 lumens) for room lighting.

The stacked PHOLED (SOLED™) is based on red, green, and blue (R-G-B) or white sub-pixel elements that are vertically stacked on top of each other versus sub-pixel elements that are laterally spaced.  This is possible because these sub-pixels employ transparent p- and n-doped organic layers enabling R, G, or B light to be emitted coaxially through the contacts, the adjacent sub-pixels, and the substrate. The area of the device can easily be halved if two PHOLEDs are stacked, and hence the substrate cost savings and device manufacturability would both significantly improve by a factor of at least two, and improvements would scale with the number of PHOLEDs stacked on each other.

At the end of Phase II, we will deliver a 6”X6” prototype lighting panel based on low-voltage, high-power-density PHOLED lighting sources that are >25 lm/W efficient, have CRI >75, and CIE coordinates similar to that of a blackbody radiator at a temperature between 2,500 K and 6,000 K.

Content dated 2/08