In-byeong Kang, CTO of LG Display, Discusses the Past, Present, and Future of Large Area OLED Panel

On January 28, Korea Display Industry Association organized the 1st OLED Frontier Forum in JW Marriott Hotel Seoul.

 

Under the title ‘OLED, Yesterday, Today, and Tomorrow’, the forum attendees could review Korean OLED research results of the past 20 odd years, and discussed regarding future OLED industry growth strategy.

 

LG Display’s CTO In-byeong Kang gave a presentation on Large Area OLED Status and Future and talked about the current status and forecast of large area OLED which is expected to become the key area of future display.

 

Since the mass production of first 55 inch OLED panel that utilized WRGB method and oxide TFT, 3 years went past. During those 3 years, Kang revealed that many innovations were carried out in terms of TFT device, compensation algorithm, OLED device, OLED materials, and processes.

 

First, the oxide TFT structure changed to coplanar method from etch stopper method, and for compensation wiring, the internal compensation was changed to external compensation. Also, he revealed that through much effort, the existing OLED device and materials were changed to new structure and high efficiency and high color gamut OLED emitting materials. Kang added that the uniformity, which becomes the most crucial point in large area OLED panel mass production, was greatly improved in Gen8 manufacturing equipment.

 

In 2013, there was only 1 LG Electronics’ OLED TV, 55 inch FHD, but recently 77 inch and 65 inch were added, and the resolution increased to UHD. Kang emphasized that although the 2013 product was priced at 11 million KRW with 100/400 nit of brightness but recent products have brightness of 150/450 nit at the reduced price of 4.2 million KRW.

 

LG Display is going through many changes recently. OLED business department began operation from last year. Large area OLED panel, which started with 8K monthly mass production at Gen8, is now being produced at 26K in full operation. Also, additional investment of 10 trillion KRW to large area panel has been decided, and new factory is being built in Paju. Kang told the audience that he heard many positive views on large area OLED at CES, and that there was a huge response regarding the 77 inch HDR video. Kang revealed confidence in the technology reporting that rather than replacing LCD, OLED could succeed as a totally different display.

 

Regarding the next 20 years, Kang forecast that the flat will move toward transparent and flexible, and OLED is the most suitable for this. He explained that the Korean government estimated this and is carrying out national project titled ‘≥60 inch UHD level transparent flexible display and applicable IT fused infotainment system development’ for the past 4 years. LG Display is responsible for this project’s overall consortium, and is planning to reveal UHD level 60 inch transparent flexible OLED panel in 2017 summer when the project is complete.

 

At the end of the presentation, Kang summarized 3 innovation factors for large area OLED. First, the substrate materials at Gen8 has to change to PI and transparent PI. Second, even for flexible substrate, the structure has to change to top emission from bottom emission, and lastly, Kang added that much more diverse applications have to be considered for flexible panel.

 

엘지기사

Will 2016 be the Year of Glasses-Free 3D Display Commercialization?

During the Pioneer Technology Seminar to Overcome Display Industry Crisis (January 14) held in South Korea, Dr. Sung-Kyu Kim of Korea Institute of Science and Technology (KIST) discussed the current issues of glasses-free 3D display and technology development for commercialization. He also revealed related KIST research results.

 

At present, the 3D display applied to TV can be divided into FPR (film patterned retarder) method and SG (shutter glass) method. Both of these methods require 3D glasses. Regarding this, Kim revealed that the glasses using method could be the biggest factor in hindering the 3D display’s accessibility. Kim announced that glasses-free 3D display development is essential particularly for outdoor advertisement applications.

 

To increase the accessibility of 3D display, glasses-free 3D display related research, such as holographic and multiview 3D display technology, has long been carried out. Kim revealed that at present the multiview 3D technology is closest to glasses-free 3D display commercialization. He added that the key issue is how much the 4 problems (crosstalk development, quantization effects between viewpoints, reduced resolution, human factor) can be controlled.

 

In order to solve these problems, Kim applied technology that forms visual field of 4 or more views between eyes and provide same image information in the adjacent area. He emphasized that this was fused with technology that tracks the location of the observer and developed improved glasses-free 3D display. He added that prototype was shown in PyeongChang 2018 Olympics PR venue and Sangwolgok Station in South Korea.

 

Kim explained problems such as human factor occur for TV and monitor where observers watch for a long period of time and future of 3D display is not bright. However, in advertisement area where people can freely watch, it could be effectively applied. He revealed that he will focus on commercialization this year and expedite development.

 

3D

Quantum Dot, Will it Rise to Become the Answer for Future Display Materials?

The interest in quantum dot materials is increasing daily. In July 2015, Professor Changhee Lee of Seoul National University received Science Technology Person of the Month prize with technology that greatly improves QLED performance and lifetime. In CES 2016, with cadmium-less quantum dot applied SUHD TV, Samsung Electronics achieved UHD TV’s color standard BT.2020 and received much attention.

 

Regarding this interest, during the Pioneer Technology Seminar to Overcome Display Industry Crisis (January 14) held in South Korea, University of Seoul’s Professor Jeong Hoon Kwak reported that quantum dot technology is a material with plenty of potential from the long-term perspective.

 

Quantum dot materials can be used with blue LED to improve LCD color gamut. Two techniques are generally used; the edge type has quantum dot placed on the sides and for surface type the quantum dot film is attached in front of BLU. Most of TV makers, excluding Sony, are using surface type. Professor Kwak explained that quantum dot can achieve desired color by adjusting the size of the particles without changing the materials. Through this, he estimated that it could replace color filter.

 

As well as increasing the LCD color gamut, as quantum dot materials emit light when connected to electricity, much like organic light emitting materials, it is anticipated that they could be used to replace the emitting materials in OLED panel. Within the industry, this technology is called QLED or QD-LED (Quantum Dot Light Emitting Diode) technology. Professor Kwak emphasized that QLED has better color gamut than OLED and has a merit of good actualization of deep blue. As QLED is basically formed through solution process, he added that solution process pixel patterning technology has to be development and device lifetime also has to increase.

 

Professor Kwak explained that as there are not many places mass producing QLED materials at present, the cost is high. However, he emphasized that because the quantum dot materials have an advantage of being easy to synthesize, from long term perspective, they can be used at lower price than OLED.

 

퀀텀닷

[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

Looking Ahead to 2016 OLED Industry through Keywords

  1. Flexible AMOLED Investment

In 2016, flexible AMOLED mass production line investment is expected to be actively carried out by Samsung Display, LG Display, BOE, and Japan Display. For Samsung Display to apply flexible AMOLED panel to the new Galaxy model, the mass production line investment is necessary. If they supply flexible AMOLED panel to Apple, volume of the flexible AMOLED mass production to be invested in 2016 is estimated to be grow significantly. LG Display also is expected to actively carry out flexible AMOLED line manufacturing equipment order for Gumi’s P6 line, as well as additional flexible AMOLED mass production line investment following Apple’s demand. BOE is estimated to seriously begin orders for Chengdu’s Gen6 45K flexible AMOLED mass production line.

 

  1. P10

With the announcement of new factory establishment and 1.84 billion KRW investment for part of facilities in Q4 2015, as the first step of the investment, LG Display began site construction for P10 line factory that can produce large area panel. However, the investment direction has not yet been decided. P10 could be directed to only producing large area LCD panel, large area OLED panel, small-to-medium size OLED panel, or large area and small-to-medium size OLED panel simultaneously. China’s Gen8 LCD facilities investment is quite advanced and BOE’s Gen10.5 LCD line investment has also been confirmed. As such how much LG Display’s large area LCD can bring profit has to be carefully considered. Additionally, with the increase of OLED TV consumption and the supply of OLED panel to Apple practically confirmed, OLED investment is essential. P10, Gen11 line, is the world’s largest factory site, and depending on the investment direction in 2016, it is estimated to affect OLED market’s opening time.

 

  1. Chinese OLED

Everdisplay is supplying AMOLED panel to some several Chinese set companies, and Visionox is also expected to actively supply AMOLED panel from 2016. As such, most of Chinese OLED panel companies’ OLED mass production preparation is anticipated to conclude in 2016. Accordingly, second investment by companies including Everdisplay, Visionox, and Tianma is analyzed to be possible and serious movement by China’s OLED industry could occur.

 

  1. Evaporation Equipment

Flexible AMOLED mass production line investment by Samsung Display, LG Display, Japan Display, and BOE, and other Chinese OLED panel companies’ additional installation are expected to be actively carried out from 2016. Amidst this, order of evaporation equipment, OLED production’s essential component, is expected to be an issue.

 

Evaporation equipment currently being used in mass production is mostly Japanese Canon Tokki’s. As this evaporation equipment has been verified in mass production, it is estimated that most companies, including Samsung Display, LG Display, BOE, and JDI, will want to order Canon Tokki’s evaporation equipment. However, as the production capa. of Canon Tokki’s evaporation equipment is limited, the issue is expected to be which panel company will be able to order early. At the same time, this could be a new opportunity for Korean evaporation equipment companies.

 

  1. Samsung OLED TV

At present, the TV industry trend is moving to OLED from LCD. Accordingly, Samsung Display is continuing research to resume their large area OLED for TV panel business. It is analyzed that Samsung Display possesses RGB OLED technology that uses SMS evaporation method, white OLED, and solution process OLED technology. However, as each technology has its drawbacks, they are carefully considering future directions. First, RGB OLED technology is estimated to lack Gen8 mother glass substrate evaporation equipment at present. Solution process OLED method has low material performance. For white OLED, as the key patents are owned by LG Display, technology that avoids these has to be first developed. Therefore, much attention is focused on which technology Samsung Display will use and invest in production line to enter the TV market.

Transparent Electrode Needs Development for Next Generation Display to Surge

Recently, with various research results regarding transparent electrode, interest in next generation transparent electrode is increasing.

 

In early December, UNIST (Ulsan National Institute of Science and Technology) developed printing technology that can arrange the Ag nanowire in the direction chosen on top of substrate. Ag nanowire is transparent electrode that can be applied to large area flexible touch panel and display products. This technology allows the surface to be flat through the fusion of nanotechnology to the existing printing process and increases transmittance.

 

Around the same time, ETRI (Electronics and Telecommunications Research Institute) developed technology that replaces thin metal electrode on top of OLED substrate with graphene transparent electrode. The metal electrode that were being used in OLED was mostly silver (Ag) material, but due to the reflection of internal light, the viewing angle changed depending on the angle. The external light also affected picture quality due to reflection. The newly developed technology used graphene that mostly does not reflect internal/external light as transparent electrode and improved transmittance and picture quality.

 

At present, ITO (indium tin oxide) is most widely used as transparent electrode materials. However, the supply is limited and flexible electronic device application is narrow. As such, the demand for the development of new materials that can replace this is greatly increasing. Particularly, as ITO is not suitable for stretchable device, the next generation transparent electrode development is considered to be a key issue for future display.

 

At 2016 Production/Process Technology Development and Application Cases by Flexible Transparent Electrode and Film Materials Seminar (December 17) held in Seoul, South Korea, Dr. Won Mok Kim of KIST (Korea Institute of Science and Technology) discussed, of many flexible transparent electrodes, TCO (transparent conductive oxide) production and process technology through presentation titled ‘TCO based flexible transparent electrode production and process technology development trend and applications’.

 

Of the transparent conductive materials, oxides have been researched the longest, and they are most widely used transparent conductive materials. Oxide including conductive materials have optical band gap of ≥3.0 eV and therefore has high transmittance and can be flexible. Kim revealed that TCO needs further improvement in conductivity and transmittance for display application.

 

Regarding transparent body, when refractive indexes of components are different, the path of light through the transparent body is refracted. When this occurs, the object becomes hazy although transparent. Haze is quantified and used to assess the transparent body’s performance. Kim explained that for solar cell the haze is purposefully increased to transmit more light to the internal active materials. However, if the display is clouded the clarity of image is reduced and therefore haze has to be lowered. To achieve this, Kim reported that the TCO’s surface roughness has to be reduced.

 

Kim revealed that there are two issues, temperature and flexibility, when TCO is used as transparent electrode. ITO’s conductivity is highest at 300 ℃, and for ZnO it is around 200 ℃. Channel cracks could occur with TCO when higher than bending strain is applied, and the crack could snap when it is bent further, destroying the device performance. Kim explained that to increase the bending strain, the thickness has to be reduced. However, when doing so as the sheet tension increases, the process has to be designed carefully considering the tradeoff.

 

Transparent electrode could be applied to display, solar cell, touch panel, and lighting among others and therefore requires much development. Although oxides have been long researched as transparent electrode materials, Kim concluded that even more diverse value can be created through fusion with next generation materials.

 

그림1

OLED and Graphene Together Achieves Innovative Technology

By Choong Hoon Yi

 

Korean research team is expected to greatly improve display’s transmittance and picture quality through fusing graphene technology, focus of much attention as the new material to OLED technology.

 

On December 15, ETRI (Electronics and Telecommunications Research Institute) replaced the thin metal electrode that was used as transparent electrode on top of the OLED substrate with graphene transparent electrode, and succeeded in developing original technology that is conductive and transparent.

 

This research results were presented in Scientific Reports, a journal from the publishers of Nature on December 2.

 

The metal electrode used in OLED until now has been mostly silver material, but due to the reflection of internal light, the viewing angle changed depending on the angle. The external light also affected picture quality due to reflection.

 

In order to solve this problem, ETRI research team focused on graphene that mostly does not reflect internal/external light. By replacing the material, the team reported that the transmittance increased by approximately 40% and reflectance improved by approximately 60%.

 

OLED was successfully lighted by attaching graphene transparent electrode to the organic layer on top of the film form (23 x 23 mm, 30 ㎛ thickness) of substrate. The research team believes this will be able to contribute much when applied to transparent OLED display and white OLED-based large area OLED display in future.

 

Particularly, unlike the existing vacuum process OLED production method, this technology can be employed via lamination where film is attached to the organic layer and graphene. Therefore, OLED can be produced through simpler process. It is expected that this can be evolved into production technology using roll to roll process.

 

Additionally, ETRI, together with Hanwha Techwin, is working on applying graphene transparent electrode to OLED’s lower electrode through collaboration of high quality graphene thin film electrode materials. The related technology development results were published online by The IEEE (Institute of Electrical and Electronics Engineers) of Selected Topics in Quantum Electronics.

 

ETRI’s Dr. Jeong-Ik Lee (soft I/O interface research section) anticipated that “this technology will be able to play a role in widening the gap with latecomer countries in OLED industry where challenging latecomers are strong”.

 

This research was carried out through Korea’s Ministry of Science, ICT and Future Planning and Institute for Information & Communications Technology Promotion (IITP)’s “Energy reducing environment adapting I/O platform technology development for future advertisement service” project and Ministry of Trade, Industry and Energy and Korea Evaluation Institute of Industrial Technology’s “Substrate size 5.5 generation or larger graphene film and OLED device/panel foundation and application technology development for graphene materials OLED transparent electrode and thin film encapsulation application”.

 

ETRI is planning to additionally develop sheet tension reducing technology by manufacturing metal in thin, grid forms and enlargement technology to produce mobile display size within 2016.

 

Through this technology, the research team produced 6 international patent applications and 6 papers. ETRI is intending to transfer the technology to graphene film and display panel companies among others. Commercialization is estimated to begin after 3 years.

1.Graphene transparent electrode applied lit OLED

1. Graphene transparent electrode applied lit OLED

 

2. OLED with existing thin metal electrode and graphene electrode OLED comparison (Left: Graphene, Right: Thin Metal, Ag)

2. OLED with existing thin metal electrode and graphene electrode OLED comparison (Left: Graphene, Right: Thin Metal, Ag)

 

3.Film including graphene transparent electrode applied to lamination process using OLED production

3. Comparison graph of existing thin metal electrode OLED and graphene electrode OLED

 

4.Film including graphene transparent electrode applied to lamination process using OLED production

4. Film including graphene transparent electrode applied to lamination process using OLED production

 

5.Graphene transparent electrode OLED Production Process

5. Graphene transparent electrode OLED Production Process

 

[Process Explanation]

After manufacturing laminated film, formed with bonding layer (BL) and PET film, using surface treated substrate, graphene transparent electrode is transferred on to the bonding layer. By laminating the laminated film that includes graphene transparent electrode on the substrate (lower electrode and organic layer), OLED where graphene transparent electrode is used as upper electrode is complete.

 

6.Graphene OLED of diverse colors

6. Graphene OLED of diverse colors

Now is the Time to Invest for OLED to be the Next Generation Display

By Hyun Jun Jang

 

이창희

 

 

On December 10, a seminar specializing company bizocean held ‘2016 Next Generation Display’s Latest Trend and Cutting Edge Industry Application Issues and Business Creation Seminar’ in Korea Technology Center. Professor Changhee Lee of Seoul National University, the first speaker of the seminar, announced that as OLED will become the technology for future display, now is the time for investment by the companies.

 

Lee reported that the display follows camera’s resolution, and although resolution has been developed up to UHD, he forecast that it will advance further. He also added that higher the resolution, the display performance that consumers demand will increase.

 

Regarding the current display market status, Lee explained that as the LCD’s margin is falling the market has to turn to OLED, but it is still expensive and capacity is low. Additionally, from the way consumers are still using the term liquid crystal regarding Samsung’s AMOLED smartphone, Lee speculated that people have difficulty in distinguishing between LCD and OLED. He told the audience that the industry should inform the public of the OLED’s differences from LCD through transparent, flexible displays that show OLED’s superior traits, and open the market through product differentiation strategy.

 

For the future display, Lee pointed out printing OLED. He explained that although printing OLED’s lifetime, particularly blue’s, falls short compared to vacuum evaporation, it is estimated to reach commercialization stage after 2-3 years. Despite the flaws in terms of materials, Lee reported that the advantages such as reduced production cost, fast tact time, and material usage efficiency will lead to the opening of the market. For these reasons, Samsung and LG are carrying out development.

 

Lee forecast that LCD, in its maturity stage of the industry life cycle, will lead the market for a while, but OLED technology will rapidly evolve and become the focus of the next generation display market. Regarding OLED TV, Lee mentioned that large area OLED mass production through printing technology is urgent in order to achieve price competitiveness. At present, OLED’s capacity is less than 1/100 of LCD. As such, even if there is demand, supply may not be able to meet it and Lee suggested the need for investment to the companies. He added that if there is low supply when the number of customers is high, the opening of the market could be delayed.

 

이창희2

Display Market Forecast Source: Professor Changhee Lee Presentation Material

 

Lee mentioned QLED as another future display technology. QLED has the same structure as OLED but uses quantum dot as the emitting materials, changing colors through different sizes. Lee reported that the color gamut is high as the wavelengths are shorter than OLED emitting materials. Also as the same material is used, QLED has an advantage of reduced material production cost and development of micro display with 2,000 ppi is complete. However, Lee added that as the lifetime is nowhere near sufficient, commercialization stage is still far away.

[2015 OLED Evaluation Seminar] Oxide TFT Technology that 2015 should Spotlight

By Hyun Jun Jang

 

During the 2015 OLED Evaluation Seminar (December 4) hosted by UBI Research, Professor Jin-Seong Park of Hanyang University gave a presentation titled OLED Oxide TFT Technology Trend, discussing oxide TFT, related industry, and technological issues as well as TFT technology that should receive the spotlight in 2016.

 

Oxide TFT has an advantage of high mobility and large area uniformity compared to a-Si TFT. As such, it is being more applied to large area OLED panel and used in LG Display’s OLED TV.

 

Park revealed that there are mainly 4 issues regarding oxide TFT and led with the reliability issue. Oxide TFT is essentially in amorphous state but when crystalized, the density and crystallizability increase; as oxygen does not move away and stay in place, defects occur less and reliability is high. Japan’s SEL and Sharp published CAAC (C-Axis Aligned Crystal) structure related oxide TFT paper, and Cornell University produced CAAC oxide TFT by increasing the substrate temperature and adjusting oxygen’s partial pressure.

 

The second issue is composition ratio. Park reported that composition ratio is the most closely related characteristic to TFT’s mobility. He revealed that recently research is being carried out centering around IGZO (indium gallium zinc oxide), but also oxide TFT research with different composition ratio is continually published. For example, ITZO (indium tin zinc oxide)’s mobility has been reported to reach 30cm/Vsec, and BOE is working on the related research. Research results, which showed increased mobility and reliability for IGZTO, which is IZTO with G added, was published, as well as ZnON (zinc oxide nitride) TFT’s 100cm/Vsec mobility. BOE demonstrated ZnO TFT applied 14.1inch AMOLED.

 

The third issue is the device structure. Park explained that efficiency can increase when top gate structure is used to oxide TFT as parasitic capacitor is not needed, but that the process is difficult. However, Park reported that JOLED revealed when self-alignment is used the number of masks used can be reduced and increases performance. This structure is applied to OLED TV by LG Display.

 

Lastly, Park gave the safety of device as the last issue. Oxide TFT can exhibit degradation effects from light, oxygen, hydrogen, and moisture. Park reported that hydrogen particularly has great effect on the safety. He explained that although the current prevailing OLED TFT is LTPS, as the panel becomes larger there will be technological competition between oxide and LTPS. Reporting that TFT which is cost efficient and shows high performance in diverse factors such as resolution will dominate the market, Park concluded his presentation.

 

 

 

박진성교수

[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.

 

홍문표 교수2