CRI - Page 4

Universal Display announced advances in their white OLED lighting panels. The new panels use a Stacked-OLED (SOLED) architecture and exceed the DOE's commercial panel target of 10,000 hours (at an initial luminance of 3,000 cd/m²) by more than 20%. The panels are 15x15cm² in size and feature 90,000 liftimre (D70), 55 lm/W efficiency and a CRI of 86. A stacked-OLED provides better lifetime, but has more layers and is more difficult to manufacture.

The company also showcased an all-phosphorescent, white OLED luminaire designed into an under-cabinet lighting system. This development was funded in part under a DOE Solid State Lighting program back in 2009. The warm-white OLED offer a power efficacy of 70 lm/W when operated at 190 lumens (~1000 cd/m²), and 61 lm/W when at 420 lumens (~2200 cd/m²). The panels operate at a low voltage of ~4 V.

Back in February, Pioneer and Mitsubishi Chemical has announced an OLED Lighting JV. Pioneer will produce OLED lighting panels, Mitsubishi Chemical will supply chemicals and will market and sell the panels through their Verbatim daughter company.

We had the good chance to speak with Verbatim regarding this new OLED business.

Q: Are there any updates on the OLED JV?
Mitsubishi Chemical Corp will start to supply samples at the end of 2010, and mass production in the middle of 2011.

Quantum Dots are getting a lot of attention lately, especially as a new SSL lighting technology. One of the companies that is working on this new tech is QD Vision. Their co-founder and CTO, Seth Coe-Sullivan has agreed to explain the technology, introduce the company, and answer a few questions.

Seth received his Ph.D in electrical engineering from MIT in 2005, writing a thesis on incorporating quantum dots in hybrid organic/inorganic LED structure. That's the technology basis of QD Vision. Seth was chosen as one of the top young entrepreneurs under the age of 30 by BusinessWeek.

QD Vision is a quantum-dot product company that delivers highly differentiated lighting solutions to major industries where color, power and design matter - these include lighting, displays, signage and defense. QD Vision’s Quantum Light™ platform enables step-change advances over other display and lighting solutions such as LCDs, plasma displays, LEDs and even organic LEDs (OLEDs). QD Vision is privately held, based in MA, US, and has several first-tier patents originating at MIT.

Q: Hello Seth, and thanks for agreeing to do this interview. Can you explain your technology? What exactly *are* quantum dots?
Quantum dots are tiny bits of semiconductor crystals with amazing optical properties that are determined not only by their material composition, but their size. QD Vision synthesizes these materials in solution, and formulates them into inks and films that we sell to our customers, enabling step-change performance and cost benefits. Our first products are Quantum Light^TM optics for solid state lighting devices, and our customers offer the most efficient, highest color quality LED lighting solutions on the market today.

UDC reported data for a series of white PHOLEDs that span a range of white colors that were designed to satisfy the requirements of differing lighting applications. These research results range from warm to cool white with varied power efficacies of 54 to 102 lumens per watt (lm/W). Depending on the specific designs employed, the color rendering indices (CRI’s) varied from 70 to 88, and lifetimes varied from 4,000 to 17,000 hours (to 70% of initial luminance at 1,000 nits*).

UDC white light OLED prototype

White OLED performance characteristics can be tuned by manipulating the OLED materials and structures that are used. To show this effect, a series of white OLEDs, from approximately 2,700 to 4,000 Kelvin, were developed that exceed the Energy Star Category A Color Specification of color rendering index (CRI) of > 75 and the Efficiency Specification of > 35 lm/W. The Energy Star lifetime specification is ? 25,000 hours (to 70% of initial luminance at 1000 nits*), however, the lifetime results for this series may be sufficient for a variety of niche products while the Company continues to develop white OLEDs that meet the requirements for more demanding applications.

UDC says that they are moving closer to meeting the U.S. Department of Energy’s solid-state lighting targets and the requirements of Energy Star, a joint specification between DOE and U.S. Environmental Protection Agency.

Panasonic is working on OLED lighting panels, using printing methods. They prototypes a high efficiency panel at Printable Electronics 2009.

The OLED lighting panel features a luminance efficiency of 40lm/W and a CRI (color rendering index) value of 95. The external quantum efficiency is 36.1%, and the half-life of the luminance exceeds 20,000 hours when the initial luminance is 1,000cd/m^2.

Read more at TechOn

Philips and Novaled reached a new record for the power efficiency of a white OLED, obtaining 32 lm/W with colour coordinates of 0,47/0,45 and a CRI of 88 at a brightness of 1000 cd/m2. That same device structure thereby simultaneously shows a lifetime of more than 20000 hours which is a major achievement for a future commercialization of the OLED technology for lighting applications.

The efficiency of the device was measured using an integrating sphere using only the forward emission cone of the OLED device without attaching any lens or any other volume type luminaire to the OLED device. This is the only method to reliably predict power efficiency values for large area lighting tiles.