In recent years, thanks to the spear of smart phones in the global market, the demand for high-end mobile phone panels has risen sharply, which has led to an increase in the overall value of OLED panel production. In particular, South Korea’s Samsung and LG have continuously expanded their mobile phone product lines into AMOLED panels. The ratio makes the global OLED output value due to the explosive growth of AMOLED. In 2013, Taiwanese companies have also begun to join the ranks of AMOLED shipments, driving the overall global OLED output value to double.
Due to the promising market prospects, manufacturers are continually strengthening the production and sales of AMOLED panels. In the future, they will focus on small and medium-sized applications and stimulate revenue growth. It is expected that the main application of AMOLED panels in the world will be mobile phones in 2010 and 2016, followed by digital cameras. . The reason is that AMOLED can expand its penetration rate in the mobile phone market by self-illumination, power saving, high contrast/reaction speed and visibility under strong light. Thanks to the vigorous adoption of high-end smartphones, AMOLED is on the market. It has become more active.
In fact, another advantage of AMOLED technology is its ability to process on flexible substrates. Based on the principle of panel technology, the LCD needs to reserve Cell Gap in the liquid crystal layer between the TFT substrate and the color filter. If the LCD substrate is changed to a soft square, when the panel is deflected, it will cause various places. The Cell Gap is uneven due to the stress relationship, so that the screen cannot be displayed. In contrast, AMOLED is a self-illuminating technology, and it is not necessary to reserve Cell Gap. If it can be combined with a low-temperature backplane process, it can be processed on a plastic substrate, which is extremely advantageous in the development of flexible products.
Soft AMOLED is coming out
In terms of the total number of AMOLED panel requirements, Glass-based will remain the focus of development by 2020, but as the market continues to demand for lighter, thinner and more impact-resistant devices, soft AMOLEDs will have opportunities. Pick up.
At this stage, Samsung and LGD are actively investing in soft AMOLED research and development; in 2013, relevant panel products have begun to appear on the market, and it is estimated that by 2017, global soft AMOLED will further reach 246 million pieces. The size of the goods.
However, soft AMOLEDs also face many technical challenges, most notably process technology and materials are not yet fully mature, so the initial focus is on "Unbreakable" characteristics, before the substrate and packaging methods reach a flexible goal. This feature first highlights the appearance of the TFT LCD panel; the next step is to emphasize the characteristics of bendable (Bendable), to promote the majority of parts to soft design.
In the third phase, it is more desirable to work with the Roll to Roll process to further reduce production costs while speeding up production and improving the reliability of the panel itself. After 2015, the panel factory plans to develop in the direction of “Foldable†to make it easier to carry, without compromising panel performance.
In addition to each step of technological evolution, there is also a very important part of the redesign of the human-machine interface. The relevant hardware factories must cooperate with the platform software industry to develop suitable new panel types after the development of soft panels. The application and operation interface can highlight its application value.
Flexible backplane process accelerates evolution
In the future, panel manufacturers should smoothly promote the mass production of flexible AMOLEDs, and organic thin film transistor (OTFT) technology in printed electronic processes will play a key role. The technology was first developed by Sony (Sony), which introduced the plastic substrate in 2007. It is also the first OTFT-based full-color OLED panel with a resolution of 160×120 (80 ppi), and the semiconductor layer material used in its OTFT. For the pentacene/phenacene derivative (Pentacene), the process temperature can be reduced to 130 ° C, to achieve the low temperature process required for plastic substrates.
At present, the electron mobility (Mobility) of OTFT has reached the level of traditional amorphous silicon (a-Si), but the stability of components still needs to be broken. Among them, the small-molecule OTFT layer generally uses vacuum thermal evaporation to form an OTFT. The polymer OTFT layer is often formed by an inkjet printing (Inkjet Printing) or a photoresist spin coating method to form an organic film, and the process temperature can be controlled below 80 ° C, which is suitable for a low temperature process of a plastic substrate.
As far as the current technology is concerned, the elemental characteristics of the small-molecule OTFT are better, but in addition to the stability of the element, the OTFT currently has disadvantages such as high driving voltage, high leakage current of the element, and uniformity of the product to be strengthened, which is unsatisfactory for the wearer.
Another oxide thin film transistor (Oxide TFT) technology combines the advantages of a-Si and low temperature polysilicon (LTPS) processes, and can be fabricated by sputtering, without having to make too many changes to existing production lines. Advantage. In addition to sputtering, Oxide TFTs can also be fabricated by low-temperature coating using indium gallium zinc oxide (IGZO) materials, which will bring more possibilities for soft AMOLED production; however, film defects in low-temperature deposited films The higher temperature deposition method will affect the electrical and reliability performance of the components. Therefore, the process temperature must also take into account the electrical properties of the film and cannot be reduced without limitation.
Soft packaging materials and coating technology challenges are arduous
Compared with TFT LCD display technology, AMOLED does not require components such as backlight, diffuser, alignment film, and particle horn, so it is more likely to be softer than TFT LCD. However, when AMOLED technology enters the soft field, in addition to overcoming the challenges of TFT components in the formation of flexible substrates, it is also necessary to use a sealing material that is highly resistant to moisture and oxygen, which is comparable to glass materials, to extend the organic components. Life expectancy, which is the development focus of the process, the current target is mainly based on film (Film) packaging.
In the form of a thin film encapsulation, a layer of barrier layer is formed on the surface to block moisture and oxygen. Generally, the barrier layer is made of inorganic materials, such as silicate (SixOy) material, which is deposited by sputtering or electron beam deposition. On the component. However, in the process of making the inorganic barrier layer, since the ability of the barrier layer material to expand or contract is limited, the internal stress of the material will be generated, and if the barrier layer is too severe, the barrier layer will be peeled off.
In addition, in order to avoid damage to the element film due to too high energy when depositing the barrier layer, in the inorganic barrier layer and the component, the organic material is often formed by vapor deposition to form a buffer layer (Buffer Layer) to protect the organic light-emitting element. However, in addition to the high transparency, this buffer layer must ensure that the components are not eroded before they are hardened, and there is no outgassing after hardening. These must be noted in the development of materials. part.
In the development of AMOLED technology, from the backplane to the package, it is the key to the overall yield decision. The analysis focuses on the development of Glass-based AMOLED and soft AMOLED. The technology of both technologies is made from backplane manufacturing and organic components. Membrane engineering, up to the back-end packaging technology, each step is interlocked, as long as the yield is too low, it will have a great impact on the overall production schedule and success rate.
Focus on small-size soft applications AMOLED challenges LCD status
For the average consumer, the technical difference between TFT LCD and AMOLED can't be distinguished by the naked eye. Whether consumers want to buy products with AMOLED panels depends on the "price" factor. Due to the existence of TFT LCD technology on the market, AMOLED must accelerate the improvement of process yield and output, and strengthen cost competitiveness, in order to continue to expand market penetration.
At present, the main force of AMOLED is still focused on small and medium-sized devices, and the 8.5-generation technology is still in the early stage of development. In 2011, Samsung's 5.5-generation AMOLED production line was put into mass production, and Samsung continued to seize the high-end smartphone market with the tactical collocation of AMOLED panels, thus accelerating the penetration rate of AMOLED. Once its 5.5-generation line has an overall yield of more than 80%, it will help Samsung accelerate the competitiveness of AMOLED products in high-end smartphones.
In addition, the characteristics of AMOLED processing on a flexible substrate are also beneficial to improve the difference from the TFT LCD. Recently, Samsung is actively developing soft AMOLED technology, in an attempt to strengthen the company's products and Apple's iPhone in a face-to-face relationship with a destructive innovation that is different from the past mobile phone design. Mobile phones are still the focus of future layout of AMOLED panel makers.
Of course, as Samsung, LG and other companies have released OLED TVs, many people will focus on large-scale AMOLED panel technology; however, the two companies are still in the AMOLED TV panel technology solution. There are many challenges to be overcome, and it will take a while to expand mass production.
Even if the AMOLED substrate is advanced to the 8.5th generation, this high-generation production technology is still developing, and the cost cannot compete with the current LCD TV in a short period of time. Therefore, whether it is a Glass-based AMOLED or a soft AMOLED technology in the future, With small and medium-sized panel output as the mainstay, relevant manufacturers have also regarded such applications as a way to effectively expand the market.
Dog Fence Wire,Invisible Fence Wire,Electric Dog Fence Wire,Invisible Dog Fence Wire
Elite-tek Electronics Ltd , https://www.aetertek.ca