Technical / Research - Page 100

Yesterday we reported that Kodak got a 1.7M$ two-year contact from the DOE to develop key technologies and processes for OLED lighting panels. There wasn't much information in the original PR, so we got Kodak to explain it a bit for us, and here's what they say:

"The object of the proposed project is to construct OLED lighting panels with efficacy (> 50 lm/W) and lifetime (>20,000 h) superior to most of the current commercially available luminaires.  The lighting panels will be constructed of 15 cm x 15 cm lighting tiles that can be used to build lighting panels of different sizes and shapes.  The architecture is based on small molecule OLED and comprises four key technology components that enable this achievement: internal light extraction-enhancement structure, low voltage design, stacked architecture, and fluorescent-phosphorescent hybrid emitters.  The proposed project will focus on developing structures and processes suitable for high volume, low cost manufacturing (ie Kodak VIST technology) of these OLED lighting panels."

Seiko Epson today announced that it has developed a new inkjet technology that enables uniform deposition of OLED materials in large size displays. They believe that this is a major step towards 37" (or larger) HD OLED TVs.

Espon 14-inch Inkjet processed OLED

Seiko Epson claim this is the first technology that can reliably form uniform organic materials on large substrates. The most widely used tech today, Vaccum Thermal Evaporation (VTE) is not able to do it because of several technical issues.

Epson has recently developed the long-awaited solution in the form of
an OLED display fabrication process that leverages the company's
proprietary Micro Piezo inkjet technology to achieve markedly greater
accuracy in organic material deposition than the conventional
technology. The process has been used in trial production to fabricate
a highly uniform prototype panel. Extremely uniform layers (volume
error ejection of multi-size droplets of ink material on a substrate so that
only the required volume of material is deposited.

Epson will give more details at SID, together with a 14" prototype display (shown above), that has a HD resolution.

The Science & Technical Research Laboratories (STRL) of Japan Broadcasting Corp (NHK) showed a new flexible OLED prototype. The 5.8" inch panel has a 213x120 resolution, 60Hz frequency, and was made using phosphorescent materials and vapor-deposition manufacturing.

Last year STRL showed an OLED prototype that was made using an inkjet process. The new OLED has double the luminance and better display uniformity.

University of Tokyo researchers developed a new kind of OLED display, that can actually stretch and deform - like rubber.They showed one displays that is shaped like a face, and showing changing expressions, and another screen that is spherical and shows weather data. The OLEDs were produced by spraying a layer of carbon nanotubes with a fluoro-rubber compound to produce a stretchy, conductive material.

The current prototypes are 100 sq centimeters, and have 256 monochrome pixels. They can be folded at least a thousand times, with no decline in quality. They are working towards better resolution and color displays.

"In the future, displays that once had to be flat can be made spherical, or even moving," says Takao Someya, professor of electronic engineering at the University of Tokyo. "A human-shaped display could be used to show medical diagnosis data, and there are various other applications."

Researchers from the University of Rochester, together with Kodak has created a nanocrystal that constantly emits light, and does not 'blink'. The findings, detailed online in the journal Nature, may
open the door to dramatically less expensive and more versatile lasers,
brighter LED lighting, and biological markers that track how a drug
interact with a cell at a level never before possible.

The researchers think that one day it'll be possible to 'paint' such nanocrystals on a large surface - creating a flat light source that may one day replace OLEDs. 

During the Light Fair in Jacob K Javits Convention Center, New York, WAC lighting is showing some beautiful OLED fixture prototypes - one mini-chandelier, and one wall sconce. They sent us a lot of info, photos and videos of these lamps...

The OLED wall sconce uses 6 color-changeable, 3" OLEDs:

Organic Lighting Technologies developed a more efficient OLED design. Here's how they describe it:

"When OLEDs are driven at high current densities to increase the light output, it is widely known that fraction of holes leak towards the electrode without participating in recombination. This reduces the optical efficiency. To prevent this, the current state of the art employs ‘hole-blocking’ layer to impose energy barrier to holes. This is a fixed barrier and at high current densities, there can still be holes crossing this barrier. The patent issued to Organic Lighting Technologies LLC discloses a unique electrical method of applying electrical bias to retard the holes leaking to the electrode (cathode). This is accomplished through an electrically conductive and transparent porous layer in place of
‘hole-blocking’ layer. The advantage of this method against the traditional ‘hole-blocking’ layer is the bias that can be varied to exercise control over the holes leaking to the electrode. In fact the leakage of the holes can be modulated on demand. In addition, the electrons can also be prevented from leaking towards anode (without participating in recombination). This is done through the incorporation of an electrically conductive and transparent porous layer on the anode side. Suitable bias is applied across these two porous layers and the electrons and holes can be continuously modulated on demand. The trick here is to deposit these critical layers in the thin film organic stack without appreciably reducing the optical transparency."

This can be used for both lighting and displays (but will be especially useful in lighting because of the high-current densities used).

OLT has been issued a patent on this technique, and they plan to either license or sell this technology. We don't know yet how much more efficient will those OLEDs be. We'll have to wait for some company to license it...

Dai Nippon Printing has developed a transparent conductive film baed on silver for the conductive particles. The film can be forms with patterns, and it is also flexible. It is designed to replace indium tin oxide (ITO) films.

DNP will start shipping samples in May 2009, and plans to start producing it full scale during the fall of 2009. DNP expects sales of 30M$ yearly of the new film by 2012.

Last month we heard of several european companies working towards OLEDs without ITO, as part of the Fast2Light project.

NeoView Kolon is showing a nice new transparent OLED prototype, apparently to be used in cars back mirrors:

Neoview Kolon transparent OLED prototype

We don't have a lot of info on this T-OLED yet...

Korea's state-run ETRI (Electronics and Telecommunications Research Institute) says they developed a transparent, oxide transistor and using this, a very stable light modulator that enhanced the aperture ratio of a AMOLEDs.

Samsung Transparent AMOLED

ETRI said it developed the new oxide transistor by using atomic layer deposition process that greatly enhances operational stability and showed excellent electronic and optical qualities. This will mean faster production of such displays.