Development Trend of Flat Panel Display Materials

1. Introduction
Although the current LCD panel economy shows signs of bottoming out and panel prices are starting to rise, TFT manufacturers are still under pressure to reduce costs. In addition to continuing to reduce the unit price of purchased materials, the panel structure continues to be simplified to reduce the amount of materials used, and at the same time, various materials are being improved to meet the current trend of green environmental protection.

2. Changes in light sources
In the NB field , LED replacing CCFL (cold cathode fluorescent lamp) has become a foregone conclusion. The next question is only about the penetration rate and the time required for complete replacement. If you want to popularize LED backlight modules, cost reduction is an inevitable issue: currently, sidelight technology is used to reduce the number of LEDs, and in terms of light guide plates , costs are reduced by reducing cycle time, making multiple holes in one mold, and improving yield. At the same time, composite optical films are used to reduce the number of optical films used, from four to two. In this way, the price of a 12-inch LED backlight module can be reduced to less than US$15, and the price difference with general CCFL backlight modules will be less than US$5.

As for TVs, cost considerations will be taken into account, and the previous method of emphasizing high color saturation and using RGB three-color LEDs will be abandoned. Instead, white light LEDs will be used to make ultra-thin LCD TVs , or local dimming control technology will be used to emphasize power saving and high contrast. Korean manufacturers are actively expanding the North American LED TV market, and the penetration rate of LED in TVs is likely to exceed 3% this year.

In addition to LED, Sony has also introduced HCFL (hot cathode fluorescent lamp) with better luminous efficiency into thinner tubes in its LCD TV product line, but the more complex manufacturing process and shorter service life are the fatal flaws of HCFL. Facing the impact of LED introduction into backlight sources, domestic CCFL manufacturers are considering transforming into the lighting industry.

3. Integration of optical films
Integrated optical films have gradually become commercialized. They have been introduced from small-sized products to large-sized products since 2007. At present, they have been introduced into the market of NB, monitors and TVs. Therefore, diffusion films and prisms Manufacturers are developing multi-functionality to reduce the use of optical films. In terms of LCD Monitor, some manufacturers have changed to two MicroLens plus a diffusion film to replace the previous design of a diffusion film on the top and bottom with BEF to reduce material costs; or only replace it with two diffusion films with focusing function (Gain Diffuser). In terms of Notebook PC, there is a design of V-Cut light guide plate plus a BEF and an upper diffusion film to replace the design of two BEFs and a diffusion film on the top and bottom, so that the number of diffusion films used can be reduced by one. In terms of LCD TV, the design of adding a diffusion film on the top and bottom of BEF replaces the practice of adding DBEF and two lower diffusion films, trying to achieve the purpose of cost down through a new design structure.

4. Polarizing plate materials

In terms of polarizing plate materials, the mainstream thickness of TAC (triacetyl cellulose) film is currently 80μm. Due to the demand for portable devices to be thin and light, it is developing towards thinness. In order to match the new production lines of 50-inch and above LCD panels and 2000mm width polarizing plate factories, TAC films are also developing towards the production of ultra-wide (1960mm~2300mm) TAC films. Currently, Fujifilm is still the only supplier of TN-type wide-angle film, while there are many suppliers of VA-type compensation film, whether it is Nitto's X-Plate, ZEON's ZEONOR, Konica's N-TAC and Fujifilm's V-TAC, etc. Because the compensation film has more choices and lower prices, the proportion of TFT factories choosing to use VA-type wide-angle technology is also increasing. Japanese manufacturers are developing "In Cell" compensation technology, which is to apply a layer of polymer liquid crystal material with compensation effect, which can reduce the manufacturing process and reduce the thickness.

5. Other materials
BM resin used in color filters is developing towards high light-shielding properties, and in the future, color filters may be manufactured using the inkjet method, so it is necessary to develop color photoresists used in the inkjet method. In terms of photoresist technology development, high sensitivity, low residual film rate, high resolution, high adhesion, and improved coating, peeling, dry etching resistance and low price are expected. In terms of target materials, because major panel manufacturers will choose different metal materials in response to the needs of conductivity or transparency, they are basically still developing towards increasing the utilization rate. Indium is expensive, has a large price change, and has limited reserves. Finding alternative materials for indium has become the focus of current ITO target manufacturers.

VI. Conclusion

In terms of technology, LCD materials have all reached a mature stage of development, and there is little chance of a major breakthrough. How to reduce panel production costs and green environmental protection have become the focus of development. It has been determined that LED will replace CCFL as the light source of NB panels. The focus of the next effort will be to introduce LED into TV panels. The integration of optical films will continue, and how to reduce costs will become the focus of the development of optical film products. Whether the coating compensation film and the new transparent electrode target material that replaces indium can be commercialized in the future is worth continuing to observe.