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>> Coexisting development of LCD and OLED display technologies 20th,Dec,2018
First, the high cost and complexity of OLED introduction and its production process
(1) Introduction to OLED
Organic Light-Emitting Diode (OLED), also known as organic electro-laser display, is the third generation display technology after CRT (Cathode Ray Tube) and LCD (Liquid Crystal Display). The basic structure of an OLED is connected to an electric positive electrode by a thin, transparent and semiconducting indium tin oxide (ITO), and another metal cathode is packaged into a sandwich-like structure. The entire structural layer includes a hole injection layer, a hole transport layer, a light-emitting layer (organic material), an electron transport layer, and an electron injection layer. When the power is supplied to an appropriate voltage, the positive hole and the cathode charge are combined in the light-emitting layer to produce light, which produces three colors of red, green and blue depending on the formulation. OLED is a dual injection type light-emitting device that converts electrical energy directly into light energy of organic semiconductor material molecules, using an electroluminescence physical mechanism. Therefore, unlike the LCD display mode, the OLED does not require a backlight, and has self-luminous characteristics. It uses a very thin organic material coating and a glass substrate, and when an electric current passes, these organic materials emit light.
(2) LCD and OLED process comparison
The TFT-LCD and OLED production processes can be divided into three parts: the front segment Array, the middle segment cell and the rear segment module. In the previous Array process, since the OLED uses the LTPS TFT backplane, a laser crystallization device and an ion doping machine are added compared to the Array process of the conventional a-Si TFT LCD. In the middle Cell process, the difference in process flow between TFT-LCD and OLED is the largest. The Cell process equipment of TFT-LCD involves a series of conventional liquid crystal panel manufacturing equipment such as PI coating/curing equipment, directional friction equipment, liquid crystal/sealing equipment, substrate alignment press, and OLEDs are made of self-luminous materials due to organic materials. RGB pixels introduce equipment such as evaporation equipment, inkjet printing equipment, and packaging machines in the process flow. The latter part of the Module process equipment is basically the same. According to industry sources, OLED investment in equipment is several times that of LCD, and only equipment depreciation is not a small amount.
(3) AMOLED process attributes determine the status of low yield and high cost
Whether it is AMOLED (currently mainstream OLED technology) or TFT-LCD, the first step in the fabrication process is the backplane process, which is to fabricate a TFT substrate. Since OLED is a current-driven device, the stability of current is very high, and the stability of current is related to the mobility of electrons. Therefore, LTPS is the best semiconductor film suitable for TFT for OLED. Generally, AMOLED adopts LTPS. The substrate is mounted with a TFT.
It is worth noting that the TFT thin film transistor functions as a driving switch in the LCD, and controls the voltage of the liquid crystal through the TFT switch, thereby controlling the rotation angle of the liquid crystal molecules, and achieving the display by shading and light transmission; The function of the switch is to control the magnitude of the current through the TFT switch to control the brightness of the light. Differences between LCD and OLED in the preparation of TFT arrays: 1) OLEDs require a large number of TFTs. Only one TFT is needed for one pixel in an LCD, and at least four TFTs are required for an OLED. 2) OLEDs are required to prepare TFTs. High, also TFT, the TFT yield in OLED is much lower than that in LCD.
In addition to yield problems and higher difficulty in TFT fabrication, AMOLEDs have further increased their manufacturing costs compared to LCD evaporation. The pixels of the AMOLED are all vapor deposited onto the LTPS. The so-called evaporation, that is, in the vacuum by current heating, electron beam bombardment heating and laser heating, etc., so that the vaporized material is evaporated into atoms or molecules, they then move in a straight line with a large free path, colliding with the surface of the substrate and condensing, Further, a film is formed. It can be said that evaporation is the essence of the OLED manufacturing process, and not only luminescent materials, metal electrodes and the like are also evaporated. The evaporation process is extremely difficult and requires a dedicated vaporizer to complete. At present, the industry recognizes that Tokki, a subsidiary of Japan's Canon, has the best technical capabilities. Only one Japanese company, Tokki, has a large-scale mass production of vapor deposition equipment. In fact, Tokki basically monopolizes the supply of global vapor deposition machines.
Second, the market penetration of OLED needs process
(1) At present, OLED screens are difficult to penetrate into the smartphone market below 2,000 yuan.
At present, due to the monopoly supply of the vapor deposition machine described above, extremely high process requirements and low yield, the cost of the OLED display is much higher than the cost of the LCD display. According to industry sources, at present, BOE's OLED screens for Huawei Mate 20 are priced at around US$80 per piece, while LCD displays of the same type with the same display quality are priced at no more than US$17 each. Therefore, consumers can more intuitively see through the terminal mobile phone market that smart phones with a price below RMB 2,000 will rarely carry OLED screens. In fact, in the domestic market and in Africa, India and other regions, more than 70% of mobile phones sold are under 2,000 yuan, which means that in the future, the smartphone market will continue to be dominated by LCD screens.
(2) OLED can not penetrate large screen display market in the short term
Shipments of large-size liquid crystal display panels (TFT LCDs) reached record highs in the third quarter of 2018. Shipment area grew 14% year-on-year to 52 million square meters, while shipments grew 7% year-on-year to 197 million units. According to Trend Force's data, global brand LCD TV shipments reached 210 million units in 2017, of which the global shipment of OLED TV market was 1.5 million units, accounting for less than 1%. According to estimates by Qunzhi Consulting in 2017, even by 2022, the penetration rate of OLEDs in the field of large-screen TVs will not exceed 3%.
The cost disadvantage of OLED unit area is further magnified in the large screen field. At the same time, large-screen OLED products are also prone to defects such as color fading, image sticking, and short life, which further restricts the penetration speed of OLEDs in the large-screen display market.
Third, LCD and OLED will be coexisting in the next 5-10 years
(1) The booming development of TFT-LCD technology has not affected the market of TN-LCD and STN-LCD
In the history of display technology development, when TFT-LCD first appeared, it was also considered to immediately replace the popular black and white screen display technologies TN-LCD and STN-LCD. But in fact, TN-LCD and STN-LCD, as black and white display devices, have the advantages of high technology maturity, reliable performance, complete industrial chain, and low cost, which can meet personal consumer electronic products, office supplies, equipment, automobiles, etc. Some basic display requirements. Today, we can still see black and white screen products in every place of life: medical equipment displays, power industry such as electricity meters (because of the large amount of national support), automotive electronics industry, such as various instrument panels, instruments for industrial equipment. Instruments, consumer electronics mp3, toys, home appliances industry such as refrigerators, washing machines, air-conditioning panels, and so on.
For many low-frequency or low-display quality applications, TN and STN LCD screens are well-suited for use, while TFT-LCD screens with higher display quality and richer colors are available in a variety of smarties. The display device shows its talents. It can be reflected from the side that the flat panel display industry has multiple levels and multiple types of structures, and different display technologies can find their respective target markets and coexist.
(2) Display industry The market size is huge, and it can accommodate multiple technologies such as LCD and OLED at the same time.
In the short term, the market demand for display products has been strong in recent years, and BOE, Tianma and other manufacturers have achieved good results with full sales. As LCD display capacity continues to shift to China, major manufacturers are optimistic about the future growth of China's LCD display industry and continue to increase investment in capacity building. According to the latest disclosure of Longley Technology (66.20 +2.32%, consultation) prospectus, Foxconn plans to invest in the establishment of a new LCD panel factory in Wisconsin, the United States to invest in the Meishan Renshou G5 generation line, Helitai (5.12 -0.78% , the diagnosis of shares) is planned to build a quasi-G6 generation line in Jinggangshan. At the same time, benefiting from the need for domestic panel manufacturers to support the domestic industrial chain, the key components of the liquid crystal display module, including backlight display modules, polarizers, etc., are also increasing their production capacity. Such as Kang Dexin (8.68 -1.03%, consultation stock), plans to invest in the construction of "Zhangjiagang Kangde New Year's production of 102 million square meters of advanced polymer membrane materials project"; Jizhi Technology (13.60 -0.80%, diagnostic stock), proposed investment Construction of large frame width and thin thickness light guide plate production base; Voge Optoelectronics (42.73 -1.18%, diagnostic stock) plans to raise about 340 million yuan for TFT-LCD glass finishing project construction. It can be seen that the LCD market is still in the development stage, which is the current mainstream display technology.
In the long run, the application range of LCD screens covers mobile phones, tablets, notebooks, monitors, vehicles, industrial control, smart homes, wearables, health care, etc., and the market scale is huge, reaching a scale of more than 100 billion yuan. The development of a variety of technologies to accommodate LCD and OLED.
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