Power consumption - Page 38

Research and Markets has released a new report on low-power next-generation displays. The report highlights the basic structure of the low power consuming next generation display market and its various sub-segments.

Technologies covered in this report includes electrochromic displays, electrophoretic displays, electrowetting, thermochromic, LED, OLED, Field Emitting Displays (FED) and electroluminescent.

There's an interesting post on DisplayDaily, trying to compute how much more efficient will an OLED TV be, when compared to the newest LCD TVs?

OLED TVs power consumption is supposed to be around 70% less than a 'plain' LCD. But the newest LCDs use a LED power source, and a new technology called Local-Area-Dimming (or LAD) actually allows the TV to use less energy in sections that use less color. This also gives the TV better contrast (black will finally be black).

According to the calculation of DisplayDaily (which is more of a guess, since we don't have large OLED TVs, and we do not have any shipping LCD with LAD yet) - an OLED TV will still take 30% less power than the best LCD. That's still very good!

Researchers (led by Johnson Chuang from the Simon Fraser University in Canada) have shown that if you choose the color set on an OLED display, you can save up to 40% of the power required.

Different colors in OLED require different power - for example yellow is more efficient than Magenta, at the same brightness. 

This can be useful, if you want to get better battery life over display quality. Here's an example of a tooth image:

The left image (tooth) is using standard colors, and the right image is using colors that require 40% less energy on an OLED. The quality is obviously better with standard colors, but almost all the details are preserved. This can be used for applications such as medical or military I guess, where power saving is key.

The OLED100.eu project is a European 3-year OLED lighting project. The 30M$ project is a followup to the OLLA project, ended in June 2008, and it is lead by Philips, OSRAM, Siemens, Novaled and the Franhofer IPMS.

Dr. Stefan Grabowsky, the project's manager has been kind enough to talk to us, answer a few questions and give us more info on the project. Dr. Stefan has a Ph.D in Physics,  from the University of Duisburg. In 2000 he joined Philips Research labs. He's working on OLEDs for several years now, with a focus on device physics and OLED stack development. Since September 2008 he is the project manager for OLED100.eu.

Q: Stefan, thanks for taking the time to do this interview. Can you tell us a bit about OLED100.eu?
OLED100.eu is an European integrated research project that has brought together a consortium of experts from leading industry and academic organizations to accelerate the development of organic light-emitting diode (OLED) technologies. It has received €12.5 million funding from the European Community’s Seventh Framework Programme to form the technological basis for efficient OLED applications for the general lighting industry in Europe.

Large-area OLED from Philips

Universal Display and Seiko Epson have been working on their inkjet printable, phosphorescent
OLED technology and materials for quite some time... They have now announced new advances in performace:

• A red P²OLED
  with CIE (0.67, 0.33), an efficiency of 10 candela per ampere (cd/A) and
  an operating lifetime of 20,000 hours, to 50% of initial luminance of
  1,000 nits


• A green P²OLED with CIE (0.33, 0.62), an
  efficiency of 34 cd/A and an operating lifetime of 25,000 hours.

Novaled and Kodak have developed  anew white PIN OLED, to be used in RGBW displays. The display is based on Novaled's p-type and n-type doped transprot layers and Kodak's emitter systems. The companies showed two devices - single unit and tandem-white OLEDs. 

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. 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

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.

Universal Display and Samsung Mobile Displays present advances in green Phosphorescent OLEDs at SID. This new material will be used in both hand-held devices and OLED TVs, extending lifetime and efficiency. UDC's red materials are already used in Samsung's AMOLED displays, and it's likely that we'll see Samsung use their green materials as well.

The companies showed a highly-efficient, green
UniversalPHOLED material that has been used in a top-emission PHOLED
device architecture. Using this approach, they achieved two
milestones. A green PHOLED with NTSC color at CIE(0.20, 0.73), high
luminous efficiency of 110 candelas per Ampere (cd/A), and a low voltage
of 3.6 V at 3,000 candelas per square meter (cd/m2) was
achieved.

A second device structure using this green PHOLED material
system also achieved an ultra-high luminous efficiency of 160 cd/A along
with CIE(0.28, 0.69) and low voltage of 3.8 V at 3,000 cd/m2.
These compare to a standard bottom-emission device with CIE(0.33, 0.62)
and 52 cd/A using this same green PHOLED material system. Replacing the
green fluorescent OLED material typically used today in an AMOLED with
this new green PHOLED can result in a significant 37% power savings.

The operational lifetime for this green PHOLED material system is also
very good. A bottom-emission device using this material system offers >
300,000 hours to 50% (extrapolated) and 15,000 hours to 90% of the
initial luminance of 1000 cd/m2 (defined as LT90). With these
top-emission devices, the LT90 lifetime is 28,000 hours and 6,400 hours,
respectively, for the 110 cd/A and 160 cd/A devices.

Universal Display and the Flexible Display Center at Arizona State University has announced a significant milestone towards a manufacturable flexible OLEDs. The new display is the first a-Si:H AMOLED display to be manufactured directly on DuPont Teijin’s polyethylene naphthalate (PEN) substrate.

The companies will be showing a 4.1" monochrome QVGA flexible OLED at SID. This display has the same brightness as normal displays with extremely low power consumption. The flexible backplane display was manufactured at the Flexible Display Center utilizing a 180°C thin film transistor process. The FDC’s facility implements traditional flat panel and semiconductor tools and processes to achieve flexible displays, enabled by its proprietary bond-debond technology to secure the plastic substrate to a rigid carrier during manufacture.

Wuhan National Laboratory for Optoelectronics (WNLO) in China say they developed new OLED display materials that are "quite something" in terms of light efficiency and chromaticity. We don't have any more details yet...

Update: Philips sent us a new white OLED square, here's our hands-on review of it

The kind folks from Philips have sent me a couple of OLED light panel samples to review. Philips have started to offer these panels online, but you can't actually get them yet. The kits are not ready, and the one I got was without a proper box and manuals. As this is just a lamp, really, it's pretty simple to use. You get a driver-box, that's got a dimmer and an on/off switch. I also got two panels:

• Small rectangle in blue color (Height 43.7mm, 47.4mm)
• White freeform (height 39.4mm, width 73.1mm)

The first thing you notice is how thin these panels are. It is amazing at first to have a light source so thin. After a while you get used to it, and now it seems strange that normal lamps have to be so big! Once these kind of lights are available, I'm sure no one will want to go back...

The freeform one has a lot of 'speckles' on it. It turns out that it got damaged in the shipment (or perhaps Israeli customs, who handled it and opened it, are to blame). Philips promised to send another white panel, so I'll be able to post new photos in a week or so. UPDATE: Philips indeed sent me a new, working white OLED square... 

Those panels have 1,000 cd/m2 brightness, are up to 20 lm/w in efficiency, and Philips say that the lifetime is 10,000 hours. They are also very thin - 1.8mm in fact. Here's how they look when lighted:

The panels are not very bright, and you need several of those panels to create a lamp. In fact when Philips showed their table lamp design, it had more then 10 panels. So if you're thinking of ordering those for a test, be sure to order enough.