Roll-to-roll - Page 5

Germany's tesa, one of the world's leading manufacturers of self-adhesive tapes, launched a new barrier adhesive tape for OLED encapsulation bonding, suitable for flexible panel production.

The new barrier adhesive tapes are transparent transfer barrier tapes that feature the company's DrySeal liner technology (which enables extreme drying of barrier adhesive). This realizes an immediate and direct encapsulation of OLED materials over the full surface without initial degradations caused by water-vapor.

The Holst Centre purchased a Kurt J. Lesker Super Spectros thermal evaporator, which expands the centre's OLED sheet-to-sheet production facilities. The new tool will increase throughput for hybrid solution-processed / evaporated OLEDs, speeding up testing of new process steps and materials.

The Holst Centre says that in the future, high volume OLED production is likely to use roll-to-roll processes, but in sheet-to-sheet processes provide an an important intermediate step. The centre will use the new Super Spectros thermal evaporator for depositing the light-emitting and charge-transport layers of small-molecule OLED devices.

OLED Encapsulation is a very hot topic, especially for flexible OLEDs. Samsung and LG are already producing flexible OLEDs, but the search for better encapsulation technologies is still on. ALD, or Atomic Layer Deposition is one candidate for future deposition of OLED encapsulation. ALD is based on Chemical Vapor Deposition (CVD) that uses two vapors (gaseous) precursors which react on the substrate which creates a solid thin film. ALD works in relatively low temperatures which means it is suitable for all substrates including plastics.

One of the leaders in ALD is Finland's Beneq. Beneq developed an inorganic barrier film called nClear which is deposited using ALD. Beneq says that nClear provides "world class" barrier performance and can be deposited at temperatures well below 100 degrees Celsius. Beneq offers the TFS-600 (Gen-2.5, 500x400 mm) which is used for industrial-scale OLED encapsulation. Beneq's director of Technical sales, Mikko Soderlund, was kind enough to answer a few questions we had on the company's technology and business. Mikko is leading the application development and commercialization of ALD-based thin-film encapsulation technology for OLEDs. He has a PhD in Photonics from Helsinki University of Technology (2009).

Corning recently announced the new second-gen Lotus XT high-performance glass suitable for OLED displays. The company has been supplying glass substrate and cover glass for OLED displays for years now. Now Corning was kind enough to participate in a Q&A session here on OLED-Info to better explain how they see the OLED market and what the future holds for Corning and OLEDs.

We talked to two Corning executives. John Bayne is Corning's High Performance Displays VP and General Manager, while Harrison Smookler is the commercial director and program manager of Willow Glass Substrates (flexible glass).

The 2.5-years 11 million Euro R2Flex project recently concluded. The project, which aimed to develop new technologies for efficient and affordable flexible OLEDs manufactured using a roll-to-roll (R2R) process, presented a flexible OLED desk luminaire prototype. It uses two OLED lighting panels, produced at COMEDD and serially connected via flexible contacting.

The flexible OLED panel was produced on a metal foil. Metal was chosen because it is a cost-effective substrate as one of the key goals in the project was lowering the production cost of OLEDs.

Beneq signed an agreement with the UK's Centre for Process Innovation (CPI) to deliver an ALD roll-to-roll unit for their thin-film barrier development platform. The equipment will be delivered to CPI in England in Q2 2014. CPI have been looking at R2R ALD technology for several years, and their first goal now is to develop full system technologies and processes to the field of clear flexible barrier encapsulation and substrate materials.

CPI OLED production line

CPI's current OLED system supports both small evaporized and soluble OLED materials. Their pilot production line uses slot die technology to allow the coating of substrates (4", 6" or 8" in size) in a highly repeatable and reproducible manner with a uniform film thickness of under 50 nm.

Sumitomo Chemical unveiled new flexible PLED lighting panels. These structured panels (they have a patterned printed on them) are produced in an ink-jet printed process. Sumitomo showed several lamp prototypes, including the one shown below:

Sumitomo plans to start volume production of such panels by March 2015 (fiscal year 2014) - using both ink-jet and roll-to-roll processes. They still need to extend the lifetime of their panels, improve the luminance performance and improve their production yield rates.

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.

Konica Minolta will unveil new flexible OLED lighting panels at the Lighting Fair 2013 exhibition in Tokyo next month (March 5). Their flexible OLEDs will debut in a "variety of forms", and visitors to KM's booth will be able to experience those new panels. 

We do not have any more information yet - hopefully KM will give technical details soon (or during the exhibition). Back in 2010 KM (together with GE) unveiled flexible OLED panel prototypes, but it seems that now the company is set to actually releasing products. The 2010 prototypes achieved 56 lm/W (and "commercially viable lifetime") using soluble materials in a roll-to-roll process. In 2010 the companies announced plans to produce those panels in 2011, but obviously this never happened. We're not sure if GE is involved in these new panels.

The EU launched a new €11.2-million 3-year project called Flex-o-Fab that aims to help commercialize flexible OLEDs within six years. The project partners will create a a pilot-scale modular yet integrated manufacturing chain for flexible OLEDs, and use it to develop reliable fabrication / production processes.

The Flex-o-Fab project will draw on technologies and expertise already used to produce glass-based OLEDs and flexible displays. It will look to migrate existing sheet-to-sheet processes to roll-to-roll (R2R) production to further reduce costs and enable high-volume production. The encapsulation, one of the key challenges of flexible panel production, will be the multilayer barrier technology developed by Holst Centre. The project will also develop novel anode technologies that will need to be transparent with low resistivity, reliable, robust and scalable for R2R production on foil substrates.