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OLED Frontier Forum’s 3rd Section Panel Discussion Summary

The 3rd section of the 1st OLED Frontier Forum (Jan 28), OLED’s Future, held a panel discussion with government, industry, and academia experts discussing OLED industry development strategy, such as next generation technology development, convergent areas, and personnel training, and future forecast. OLEDNET summarized the answers that each expert gave to the questions of the panel chair (Professor Changhee Lee, Seoul National University).

 

Jun-hyung Souk (Professor, Sungkyunkwan University)

For SDC mobile, as the OLED depreciation is ending the OLED production cost is becoming almost the same as LCD. If OLED related experts stay within Korean industry as well as the technology, Korea can continue to lead for 4-5 years. In order to achieve the continued leadership, differentiation through flexible R2R has to be carried out, as well as the materials and encapsulation technology development.

 

 

Sung-Chul Kim (CTO, SDC)

As a-Si is an existing technology, there is no room for further advancement. Sharp’s difficulty in panel business is due to lack of technology research on the panel. Because one technology can only be used for approximately 7 months, diverse technology development is required.

 

 

In-byeong Kang (CTO, LGD)

Fast organizations cannot but win. Therefore, rapid change to OLED from LCD is needed. As difficult is the technology, cooperation between academia and industry is needed. Now is the time when this cooperation for next generation technology development is more in demand. LGD is putting in much effort for OLED profitability.

 

 

Sung-Jin Kim (Vice President, Toray Advanced Materials Korea)

Cooperation between materials and manufacturing equipment companies is important in solution process materials development. Particularly, how to control dry process is an important issue. Also, Kim expects the current solution process materials development to show tangible results in 3-5 years.

 

 

Junyeob Lee (Professor, Sungkyunkwan University)

Solution process is favorable for materials optimization. From the initial concentration on polymer materials, recently small molecule materials focused soluble materials development is being carried out, and how to implement common layer is an issue. Emitting layer is using the small molecule materials that are being used as evaporation materials. The difference is the higher cost as the solvent is used. Also, as there is an issue (formulation problem) when used in large area, solution is required.

 

 

Kyoung-Soo Kim (Vice President, Korea Display Industry Association)

Expert acquirement is a key issue. Through upgraded cooperation between industry and academia, and industries, cooperation between panel, manufacturing equipment, and materials has to progress into a positive cycle. Also the open platform regarding new OLED application is needed.

 

 

Young-Ho Park (PD, Korea Evaluation Institute of Industrial Technology)

Flexible display competitiveness acquirement is a big concern. Programs for challenging R&D, and high added value product/technology development, and R&D infra establishment (highly cost-effective R&D) have to be considered.

 

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[Lighting Japan 2016] Yamagata University Develops Low Cost Flexible OLED Encapsulation

Innovation Center for Organic Electronics in Yamagata University in Japan discussed low cost flexible OLED encapsulation in Lighting Japan 2016 conference. Existing flexible OLED encapsulation mainly used hybrid encapsulation structure that forms multi-layer thin film passivation layers on top of OLED, and then applying adhesive organic material and laminating gas barrier film. The encapsulation structure presented by Yamagata University forms, of the hybrid encapsulation structure, thermoset resin and barrier film above OLED without multi-layer thin film passivation, and laminate at approximately 130 °C. Yamagata University announced that they were successful in transparent flexible OLED panel development on January 13 using encapsulation, and that this panel will be presented in Printable Electronics 2016 in Tokyo from January 27.

 

The OLED panel to be exhibited is a leaf shaped of 45 mm width, 110 mm length, weighs less than 1.2g, and 250 um thick transparent film substrate that can be folded.

 

According to Yamagata University, if the newly developed encapsulation is applied, the OLED lighting panel price can be reduced as passivation layer is not used. Also, Yamagata University revealed as it can satisfy both transparent and flexible categories simultaneously, it is estimated that it will become a key technology in future transparent flexible OLED lighting development.

 

Low Cost Flexible OLED Encapsulation, Yamagata University

Low Cost Flexible OLED Encapsulation, Yamagata University

[2015 OLED Evaluation Seminar] Professor Hong Mun-Pyo of Korea University Retraces Flexible OLED’s Key Issues

By Hyun Jun Jang

 

During the 2015 OLED Evaluation Seminar (December 4) hosted by UBI Research, Professor Hong Mun-Pyo of Korea University gave a talk titled Flexible AMOLED Gas Barrier Technology Development Status. Through this presentation, he discussed in detail flexible OLED’s outline, technological issues, and encapsulation among other key issues.

 

Flexible display signifies a display that was produced on top of flexible substrate, and not an existing glass substrate, which can bend, fold, or roll without breaking. Hong emphasized flexible display is the next generation display that can simultaneously satisfy consumers and panel makers, and an area that OLED can be more valuable compared to LCD.

 

There are 3 essential issues in flexible display, substrate, TFT array, and display processes, as well as ancillary issues such as application and cost. Hong reported key issues regarding substrate and display process.

 

Flexible display uses plastic substrate, instead of glass, that is strong against shock and can bend. Therefore, handling technology that manages plastic substrate is considered a key technology in flexible display production. Hong revealed that for handling technology, a film lamination method and vanish coating method are mainly used. A film lamination method is where plastic substrate is attached to carrier glass using adhesive before being processed and a vanish coating method is where the PI substrate is coated to the carrier glass before processing. He emphasized that no matter which method is used, the debonding technology used to detach the plastic substrate from the glass plays a crucial role in deciding yield.

 

Hong followed the substrate discussion with encapsulation technology. Encapsulation technology prevents moisture and oxygen that affect OLED panel’s performance from infiltrating in order to increase the display’s lifetime. As it is a core process that decides OLED panel’s yield, OLED panel production companies are focusing on optimum encapsulation technology development.

 

Key issues of encapsulation technology that is currently being applied to flexible OLED, barrier coating related issues are considered the most important. Barrier coating is the coating applied to the plastic substrate to overcome the limitations that occur as existing glass substrate is replaced by plastic. For flexible encapsulation, as can type or frit seal technologies that were used for glass encapsulation cannot be used, face seal or TFE technologies that can be applied to flexible are used. Also, as the permeability of oxygen and moisture has to be 10-6g/m2day or less, high performing barrier coating technology is needed.

 

When barrier coating is used to flexible OLED, generally 3 problems occur. Firstly, physically cracks or particles can develop. Regarding this, Hong explained that this issue can be solved if process is properly maintained. The second problem is micro defects that can arise on the surface of plastic film, which can be solved through optimized process, according to Hong. Lastly, nano-sized pin holes can come up. Hong revealed that multi-layers of barrier coating can solve this problem.

 

Generally, when OLED panel is produced the thickness of encapsulation layer is not a big issue. However, Hong emphasized that the thickness becomes a core issue when producing flexible OLED panel. He reported that hybrid structure of encapsulation where gas barrier cover plate is attached to passivation layer placed via PECVD can be the solution.

 

Although the most suitable process technology for hybrid encapsulation production is R2R, as appropriate results are not obtained when CVD is applied to R2R, Hong reported that research is being carried out toward the sputtering using direction. He revealed that if reflection plate is added to the sputtering equipment and neutron beam release is induced, defects that occur during the sputtering process can be reduced as the target thin film stabilizes.

 

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[Expert Talk] Dr. Mauro Riva, SAES Group’s OLED/OLET Business Developer, on Encapsulation

Dr. Mauro Riva, SAES Group’s OLED/OLET business developer, discussed his views on OLED in general as well as SAES Group’s technology through his interview with the OLEDNET and presentation at the OLEDs World Summit (October 27-29) titled ‘The Encapsulation Question’.

 

Encapsulation is required to prevent the oxidation of emitting and electrode materials by blocking moisture and oxygen. It also protects the device from mechanical and physical shocks. The basic configurations of encapsulation can be divided into 3: glass-to-glass, barrier film lamination, and thin film encapsulation methods. Glass-to-glass configuration is applied to rigid AMOLED for mass produced mobile, barrier film lamination and thin film encapsulation methods are used for flexible AMOLED, and barrier film lamination is used for large area AMOLED panel for TV.

 

Source: SAES Group, OLEDs World Summit 2015

Source: SAES Group, OLEDs World Summit 2015

 

According to Dr. Riva OLED encapsulation is still facing the same issues it had since the beginning: OLED materials’ extreme sensitivity to oxidizing agents and moisture in particular. He added that OLED materials can also be very sensitive to heat or radiations, generating many process constraints. Encapsulation technology is directly related to the lifetime of the OLED device and Dr. Riva raised several questions regarding the current issues surrounding the technology including the appropriate target lifetime, best definition of “lifetime”, and reliability of the “accelerated tests”. He emphasized that while much progress have been made, a “single optimal, universal solution” does not exist yet to meet various encapsulation requirements depending on OLED architecture, materials, environment, applications, etc. As such, encapsulation materials have to be specifically engineered to meet different types of OLED devices while having “exceptionally high barrier properties, and active fillers or getters, capable of absorbing water on a single molecule basis”. Thus, perfecting this technology is a very challenging task, and, according to Dr. Riva, something that requires in depth collaboration between advance encapsulation materials providers and OLED makers.

 

For their part in this technology progression, Dr. Riva reported that SAES Group provides a very large portfolio of active edge sealants, active transparent fillers, and dispensable getters. He explained that the portfolio is the results of deep know-how in functional polymer composites (FPC), “specially tailored to address customers’ specific OLED designs and processes”. Discussing the FPC during his talk in OLEDs World Summit, Dr. Riva emphasized the versatility of this approach.

 

Source: SAES Group, OLEDs World Summit 2015

Source: SAES Group, OLEDs World Summit 2015

 

Regarding application methods for SAES Group’s FPC products, Dr. Riva explained that they can be dispensed via screen printing, blading, syringe, ink-jetting, ODF (one drop filling), and even be employed in thin film encapsulation structures, to make them simpler and more reliable. Furthermore, Dr. Riva reported that while SAES Group considers syringe dispensing as one of the main methods for applying their FPC, “ink-jetting is also becoming more and more widespread, together with ODF, especially for active fillers”.

 

Dr. Riva believes the FPC could play an important role in making the encapsulation more effective, and that SAES Group can “leverage on its advanced materials expertise” and in-depth getter/purification knowledge, to “perfect FPC based encapsulation solutions for OLEDs”. 11% of SAES Group’s net sales is allocated to Research and Innovation every year with strong cooperation with universities and R&D centers. The company is collaborating with many companies in diverse areas of interest such as OLED lighting, manufacturing equipment, specialized food packaging, and gas barrier films. This proactive and collaborating approach will enable the SAES Group to play a key role in developing more marketable OLED devices.

 

AIXTRON Supplies R&D Encapsulation Equipment OPTACAP

On 9 September, AIXTRON, a deposition equipment production company, revealed that they supplied encapsulation equipment OPTACAP to a major Asian display maker.

 

OPTACAP encapsulation is a research equipment that handles substrates size of 200mm x 200mm. AIXTRON revealed that this was ordered in the third quarter in 2015 and is scheduled to be delivered in the first quarter of 2016. The OPTACAP’s PECVD technology enables the deposition of barrier film used in TFE process of OLED display, OLED lighting, organic photovoltaic and flexible electronic device.

 

CTO (chief technology officer) of AIXTRON, Andreas Toennis, said, “thin-film encapsulation is an essential step within the OLED manufacturing process. Therefore, we are delighted to be able to provide an innovative solution to the industry which delivers excellent barrier films at high throughput. Therefore, this solution contributes to a significant reduction of manufacturing costs for the critical encapsulation process step within the production of flexible as well as rigid OLED devices”.

 

In April 2015, AIXTRON acquired PlasmaSi, located in Silicon Valley in order to develop OPTACAP encapsulation technology.

Encapsulation Technology That Can Greatly Increase OLED Lifetime Unveiled

On July 29, at Chungcheong Display Forum held in Hoseo University in South Korea, an encapsulation technology that can greatly increase OLED lifetime was revealed.

 

Encapsulation technology prevents permeation of oxygen and moisture from affecting OLED panel’s performance and increases lifetime. As it is also the last process that decides OLED panel yield, OLED panel manufacturing companies are focused on finding the most optimal encapsulation technology.

 

The flexible OLED panel that is currently being mass produced uses hybrid structure of encapsulation where gas barrier cover plate is applied to the organic and inorganic stacks of passivation.

 

During this process, because cover plate with gas barrier characteristics is the key factor in deciding encapsulation performance the materials and technology are very important. The level of encapsulation that OLED panel requires is approximately 10-6g/m2day. The unit signifies the amount of permeation for 1m2 area a day. This amount is same as 1 drop of water in an area size of 6 World Cup stadiums.

 

Generally sputtering technology is used to form gas barrier layer. Sputtering technology is an evaporation technique where ions of the target material is coated to the substrate as noble gas, ionized via high voltage, collides against coating material.

 

This type of sputtering technology creates particles and defects during process. As such, in order to be applied to OLED, multilayer is required leading to a decrease in productivity and increase in production cost.

 

However, at the Chungcheong Display Forum, Professor MunPyo Hong of Korea University, revealed that defect that occurs during the existing sputtering process can be reduced by stabilizing target layer through installing reflector which induces neutral beam to be released.

 

According to Hong, this technology is sufficient to achieve the OLED level encapsulation standard of 10-6g/m2day even using a single layer. He revealed that this technology will be able to reduce the production cost and increase the productivity.

 

(a)(a)Device Immediately After Production (b) Device with Insufficient Encapsulation with Insufficient Encapsulation (dark spot and pixel shrinkage occurs after certain amount of time) Source: UBI Research

(a) Device Immediately After Production (b) Device with Insufficient Encapsulation with Insufficient Encapsulation
(dark spot and pixel shrinkage occurs after certain amount of time)
Source: UBI Research

[Analyst Column] Encapsulation Technology, Where is it Going?

Yi Choong Hoon Yi, Chief Analysis / UBI Research

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OLED market is heating up again. Rigid OLED market growth was temporarily stalled but with Samsung Electronics and LG Electronics’ new flexible (plastic) OLED products, Galaxy S6 Edge and G Flex 2 respectively, the smart phone market’s temperature is rising. In order to maintain the storm that iPhone brought, Apple is preparing to release smart watch equipped with LG Display’s plastic OLED. Additionally, LG Elec. is targeting the premium TV market with their 55 inch and 65 inch UHD OLED TV.

OLED panel leading company Samsung Display decided on Gen 6 line’s additional investment for flexible OLED production expansion. LG Display also decided on supplemental extension of Gen 4 line in Paju responding to the shortage of plastic OLED supply. Furthermore, JDI is joining in and expected to begin Gen 6 flexible OLED line establishment soon.

Recently announced Samsung Display’s decision to invest in large OLED line is the most encouraging news. Frontline leader in OLED display, Samsung Display mass produced 55 inch OLED panel using RGB OLED and LTPS TFT technology. However, halting the production, Samsung Display explored for technology with better business value and recently selected to produce large OLED panel using WRGB OLED technology.

OLED panel production technology can be largely separated into 3 parts: TFT, OLED, and encapsulation. Large OLED panel production technology is very difficult to obtain yield compared to small panel. Therefore, while the above 3 technologies are important in producing good panel, technology that can acquire good yield for mass production can guarantee business value. Particularly, as encapsulation is the last process, the final yield depends on the encapsulation method.

In that case, what encapsulation technology is most suitable for large area OLED panel production? As OLEDNET article published on January 12 mentions, from the technology trend perspective the answer is hybrid encapsulation technology. This technology is completed with device’s passivation film, moisture proof top plate that can cover the top, and organic material that adhere the top and passivation film. From the design trend perspective, the technology must be able to bend. Recently, the TV market is moving toward curved design, and to respond to rollable display as well the top plate has to be metal rather than glass. (Reference, 2015 OLED Encapsulation Report, UBI Research)

Hybrid encapsulation technology can be further divided into film method and dam & fill method depending on the adhesive structure between top plate and passivation film. Film method is being applied to mass production by LG Display, and dam & fill method was developed led by Sony. This method dispenses adhesive polymer liquid after organic dam installation on the panel border. This can only be used when the top plate is glass. LG Display completes the process by sealing the metal plate laminated with adhesive film to the device. A best suited technology for curved TV and rollable TV production.

The OLED panel for TV production technology decided by Samsung Display was initially known to select WRGB OLED structure similar to LG Display, but TFT and encapsulation technology have not yet been revealed. However, TFT technology is highly likely to be oxide TFT. (Reference February 27 OLEDNET article) LTPS TFT has high investment cost compared to oxide TFT and has low business value at similar performance.

What is left is encapsulation technology. For this technology also a method already commercialized by LG Display, film lamination method, is most suitable since metal plate is favorable for curved design. Metal plates is strong against external shocks and favorable for heat sink. Glass has lower heat conductivity compared to metal and requires additional protection against heat; this means that production cost can only increase. Considering design, protection against external shocks, and reduced heat sink cost, LG Display’s hybrid encapsulation technology that uses metal plate is the most ideal. Therefore, the direction that Samsung Display should also head toward is metal plate and film using method.

Although small OLED for mobile technology developed by Samsung Display became the norm, it is estimated that LG Display’s technology will become standard for large OLED panel production.

[Analyst Column]The key technology to realize 8K OLED TV is transparent hybrid encapsulation technology

Choong-hoon Yi / Chief Analyst / UBI Research ubiyi@ubiresearch.co.kr

Along with LG Electronics, Panasonic and Skyworth joined the UHD TV industry as releasing the 55-inch, 65-inch and 77-inch UHD OLED TVs at CES2015.

In response to this, the LCD TV manufacturers unveiled numerous new LCD TVs at CES2015 combining different technologies of QD, HDR, and curved design.

OLED is catching up with LCD in terms of resolution and LCD began to compete with OLED in respect of curvature and color.

There were competitions with regard to resolution between OLED and LCD in the history of smartphones. As the resolution of small and medium LCD improves in order to distinguish itself from OLED starting from 200ppi in 2010 to over 500ppi through the Retina (326ppi), OLED accomplished the equivalent resolution through the FMM mask and pentile technologies.

The LCD TV industries are anticipated to develop products with ultrahigh resolution in consideration of the small and medium OLED. And the OLED TV industries are reviewing the technologies to answer to this trend of ultrahigh resolution.

The resolution over 8K is available for OLED TV by either converting the bottom emission structure which is currently applied to the existing 4K OLED TV to the top emission structure with higher aperture ratio or producing the RGB OLED panel with the solution process.

Sony already developed and introduced the world’s first 4K OLED TV with the top emission technology at CES2013. Employed for Samsung Electronics’ Galaxy series, the top emission structure can be applied to a large area but the complication is in the transparent encapsulation.

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It is hard to use the frit technology currently used in small and medium to a large OLED for its durability issue. The hybrid encapsulation method using the transparent encapsulation film emerges as the optimum alternative and the developments are set in that direction.

The substantial market growth is expected as the transparent hybrid encapsulation technology is critical in realizing a large area flexible OLED and transparent OLED besides the ultrahigh resolution using the top emission.

 

 

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