Technical / Research - Page 68

A couple of weeks ago we reported about new organic-TFT developed by University of Florida researchers, and now we've got some more info. The new transistor design is carbon nanotube based and it can efficiently drive the high-currents OLEDs need, at lower voltages than other designs.

The researchers not only designed a new transistor, but they combined it with emitting materials into a single design, called an OLET (we first reported about OLETs back in May 2010). The new design is called a CN-VOLET (Carbon Nanotube Vertical OLET). They say that this new design is more than eight-times more efficient than other competing devices. It also exhibits longer lifetime and should be easy to manufacture.

Universal Display reports advances in its UniversalP2OLED solution-processable material's performance: lifetime, efficiency and operation voltage. Solution-processable OLEDs can be used in ink-jet printing and other manufacturing techniques that can result in cost-effective production of large-size OLED panels. UDC says that commercial viability is now "in sight".

• The green P2OLED system, which offers a luminous efficiency of 68 candelas per Ampere (cd/A), has now achieved 175,000 hours of operating lifetime. This is a 34% increase over the last reported value (130,000 hours).
• The red P2OLED system, with a luminous efficiency of 18 cd/A, now offers an operating lifetime of 125,000 hours (a 100% increase over the last reported value of 62,000)
• The light blue P2OLED system now offers a luminous efficiency of 29 cd/A and 8,000 hours of operating lifetime (a 60% increase in efficiency and lifetime).

Universal Display unveiled a new single-layer hybrid organic-inorganic encapsulation technology for OLED (or other thin film devices). The new technology can be used on rigid and flexible substrates and may accelerate commercialization of plastic substrates based displays.

The new technology uses environmentally-benign and non-toxic materials in a potentially low-cost process. UDC collaborated with the Flexible Display Center (FDC) at Arizona State University to demonstrate the technology effectiveness, and the implementation was supported by the US DoD, DoE and the National Science Foundation.

Researchers from the University of Toronto discovered that using chlorine can drastically reduce OLED device complexity and improve its efficiency. In fact in their tests, the efficiency more than doubled at very high brightness. The idea is to add a one-atom thick sheet of chlorine on the ITO electrode used in OLEDs. This can make the electrode a more efficient electrical transport - and so there's no need for a 'transport' layer as used in current designs.

The researchers developed a UV light assisted process to achieve chlorination (which negates the need for chlorine gas) - and so the whole process is easy to engineer, safe and reliable. The new OLED which used the CI-ITO electrode achieved a record efficiency of 50% at 10,000 cd/m².

Henkel announced it will join the Holst Centre, and the two companies will partner on flexible electronics. Henkel is into adhesives and sealants - and these kind of technologies are important for flexible OLED lighting panels and displays.

This joint research will allow Henkel to further evaluate and develop its optically clear, electrically conductive and moisture barrier technologies on actual devices.

Researchers from the University of Florida developed a new OTFT for AMOLED displays. The new OTFT has a novel stacked vertical structure that automatically gives a large gate area. A thin gate can be achieved by spin-coating or other techniques. They say that 200µm resolution is sufficient to lay out the drain electrode which is the most demanding feature, compared with 25µm needed for some lateral TFTs.

The team prepares a paper that is due very soon to explain the new OTFT. There are still challenges of course to overcome in this design.

We just got word from Verbatim that their Velve OLED lighting sample kits will start shipping in May. The price in Japan will be ¥90,000 ($1,050), we do not know the European or US price yet (it seems that Mitsubishi will market these in Japan and Verbatim will market in Europe). Full scale production will begin in July, and then prices will probably drop.

The sample kits include one color-tunable and dimmable OLED module, USB cable, software and a power adapter. Verbatim's software will allow you to program a color sequence (the default one will be red, green, blue, cyan, magenta, yellow). The panel itself is 145x207mm in size, and the actual emitting area is 123x123mm. The lifetime is 8,000 hours at 1000 cd/m². You can read the data sheet here.

Lumiotec sent us some interesting updates today. First of all, the company is already producing and shipping their second generation panels. They call these the 'standard' panels, or Version 2.0. The older panels (like the one we reviewed a while back) is referred to as 'pre series' or Version 1.0. The new panels offer better efficiency and lifetime and come in a variety of shapes, sizes and colors. They also cost a lot less then the first version - ranging from €115 to €350 (so the large square is down from around €700 to €260!). You can see Lumiotec's updated datasheet here.

A while back we reported that Rohm developed a new OLED lighting panel that uses a red phosphorescent material - which results in a much more efficient panel (25-30lm/W). We assumed that Lumiotec's Version 2.0 panels use Rohm's new panels - but sadly this is not the case. The Ver 2.0 are still all fluorescent, and the efficiency is just a little over 10.5lm/W. Lumiotec says that they consider phosphorescent materials a must for efficient panels and they do plan to go down that route in the future.

Japan's JSR says that the Lucera thin film production system is now operable and they are already making samples. The Lucera is an optically isotropic transparent film that offers" superior transparency, optical isotropy, high refractive index, low heat-shrinkable, low dielectric constant and low dielectric loss tangent, low water absorption and a good combine flame resistance". The Lucera has an operating temperature of 260°C or higher and can be used in touch panels, OLED displays and lighting panels, insulating film and more.

Toray developed a new silver nano-wire based transparent conductive film that offers a light transmittance of 90% or more and surface resistivity, which is a measure of conductivity, between 150 and 250 ohm/sq- using wet coating method (Toray says that this is the world's best film in terms of transparency and conductivity). The new material also offers superior flexibility, natural coloration, durability and workability. Toray will begin mass production in the 'near future'.

The new material was developed in partnership with Cambrios (who are also collaborating with Plextronics). The companies say that this new material can find applications in touch panels, solar cells and OLED electrodes.