Technical / Research - Page 45

Indium-Tin-Oxide (ITO) is currently used in OLED panels for the transparent cathode (or anode in top-emission OLEDs). ITO is useful because it is conductive and transparent, but its supply is limited (even though companies are now harvesting ITO from recycled electronics devices) and it's also brittle (so it's not suitable for flexible panels) and so companies are looking for alternatives.

Some products that use Cambrios Ag-Wires

One possible alternative are silver wires (or ag-wire). This technology is pioneered by Cambrios - a company established in 2002 with an aim to commercialize Ag-Wire based products. Cambrios ClearOhm is a Ag-Wire coating material used to create transparent conductive layers. ClearOhm can be deposited on thin films using a roll-to-roll (R2R) process, and is compatible with plastic substrates. It's also possible to use a sheet process on glass or plastic. Cambrios has filed over 175 patents for this technology and they claim they hold basic ag-wire patents. My friend Sri Peruvemba recently joined the company to become its chief marketing officer and he was kind enough to discuss their technology with me and help me with this article.

Merck inaugurated their new Taiwanese Technology Development Center, which will develop new material technologies in collaboration with local companies. The main focus of this new center will be OLED materials. Other areas of research will include flexible displays, LED lighting and 3D techniques. Merck already has an OLED R&D lab in Korea.

Merck's OLED product portfolio covers transport materials as well as emitters and other functional layers. The company is focusing on soluble OLED materials, and they say that the performance gap between vapor and printable materials is closed in R&D. Merck OLED materials are "used commercially in many products on the market".

Novaled and Cambrios have jointly developed a metal grid free 10x10 cm OLED lighting panel that uses Cambrios silver nanowire ClearOhm transparent electrode material. ClearOhm is used instead of the ITO that is usually used.

Cambrios says that ITO's limited conductivity (20 ohms/sq on glass and 50-100 ohms/sq on flexible plastic film) leads to considerable voltage drops over lengths larger than 2 centimeters. This means that metal grids are required on top of the ITO (you can see such lines in some OLED panels, for example on the Osram Orbeos). ClearOhm has a low resistance (5 ohms/sq with greater than 90 percent transmission) independent on the carrier substrate.

SID 2013, the world's most prominent display conference will take place next month (May 19, in Vancouver, Canada) - and they now published some technical papars that will be discussed during the conference. And there's some interesting stuff in there.

First up is AU Optronics paper, describing how the company developed the world's largest OLED panel: a 65" direct-emission Oxide TFT one. This panel, that was produced using an FMM process, features a long-range threshold voltage uniformity of 0.34 V, and the dam and fill encapsulation process is simple and highly stable.

Fraunhofer COMEDD installed a new cluster system in their production line for the processing of 8" wafers. This upgrade of the pilot line offers a wide range of processes, including evaporation of organic and inorganic materials, metal evaporation, electron beam evaporation and high quality thin-film encapsulation). COMEDD's new line was made by SNU Precision. This new line will be especially useful for research on OLED microdisplays in interactive data eyeglasses and future integrated OLED-on-Silicon opto-sensors

COMEDD was established in 2009 as a department in at the Fraunhofer IPMS, but it is now an independent institute at Fraunhofer. Two days ago (on April 9) they conducted the official opening ceremony of the new institute. Congratulations guys!

Fluxim released version 3.3 of their SETFOS simulation software, used to study OLED and OPVs. Version 3.3 includes the following improvements over the previous version (released in March 2011):

• multi-threading support for speed improvement on multicore PCs
• a completely re-designed graphical user interface (GUI)
• a solver for electrical impedance spectroscopy simulations
• an algorithm for scalar light scattering

According to Japan Economic Newswire, Sharp decided to launch a three-year project to develop OLED mass production technologies. Sharp's mass production technology will be ready by 2016 and then the company will decide whether they will build their own OLED fab or outsource the production to other makers or even license or sell the technology. It's not clear whether Sharp aims to make OLEDs for mobile displays, flexible OLEDs or OLED TV panels.

According to JEN Sharp will release its 3-year business plan on May 14, and then we'll know whether the OLED project is indeed included in their plan. The report says that Sharp plans to use "unique materials" that will make "clearer OLED images". Perhaps they mean SEL's and Sharp's new crystal structure innovation, used in the company's latest OLED prototypes.

In December 2012 we posted about Japan's Kyushu University new rare-metal free fluorescent OLED emitter materials that achieve 100% emission efficiency. Now the International Society for Optics and Photonics (SPIE) released a new video featuring Kyushu's professor Chihaya Adachi. Following a rather long introduction into his lab and his own biography, professor Adachi explains their thermally activated delayed fluorescence (TADF) technology (also called hyperfluorescence).

Adachi says that are seeking a commercialization partner, and they still need to study the degradation mechanism and expand the emission spectrum. Towards the end of this video you can view a couple of prototype monochrome (green) panels that use their new emitters.

Nanomarkets released a new white paper about solution-Processed OLEDs. They estimate that in order for the OLED market to grow significantly for TV and lighting applications, companies must adopt solution-processable materials. Soluble OLEDs have been researched for years with very little outcome outside of the lab. But Nanomarkets believes that the current problems can be fixed, and are worth fixing.

Soluble OLED materials and appropriate processes are being researched by Sumitomo, DuPont, Pioneer, UDC, Solvay, Marck and others. They estimate that the first panels to be made using these materials will be Pioneer's (together with Mitsubishi) OLED lighting panels - planned for 2014. Nanomarkets thinks that if Pioneer succeeded, it may push GE back into the OLED game with their own soluble material solutions. It's interesting that Nanomarkets does not mention Panasonic's OLED TV prototype that uses Sumitomo's P-OLED materials.

Last month we reported about the EU's new €11.2-million 3-year project called Flex-o-Fab that aims to help commercialize flexible OLEDs within six years. Today we hear that one of the project partners, UK's Epigem, will get €444,000 to produce anode film based on its existing Epimesh product. Epimesh features very low sheet resistance and high optical transparency.

Epimesh film is an ultra-fine metal mesh embedded into a polymer coating which is adhesively bonded onto one side of a flexible carrier film. Epigem says that light transmission (through both the metal grid and the polymer layers) is above 90%.