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High color gamut

Future Analysis of Quantum Dot TV Technology


With the development of display technologies, the TFT-LCD industry, which has dominated the display industry for decades, has been greatly challenged. OLED has entered mass production and has been widely adopted in the field of smartphones. Emerging technologies such as MicroLED and QDLED are also in full swing. The transformation of the TFT-LCD industry has become an irreversible trend Under the aggressive OLED high-contrast (CR) and wide color gamut characteristics, the TFT-LCD industry focused on improving the characteristics of LCD color gamut and proposed the concept of "quantum dot TV." However, the so-called " quantum-dot TVs" do not use QDs to directly display the QDLEDs. Instead, they only add a QD film to the conventional TFT-LCD backlight. The function of this QD film is to convert part of the blue light emitted by the backlight into green and red light with a narrow wavelength distribution, which is equivalent to the same effect as the conventional phosphor.


The green and red light converted by the QD film has a narrow wavelength distribution and can be well matched with the CF high light transmittance band of the LCD, so that light loss can be reduced and a certain light efficiency can be improved. Further, since   the wavelength distribution is very narrow, RGB monochromatic light with higher color purity (saturation) can be realized, so the color gamut can become large Therefore, the technological breakthrough of "QD TV" is not disruptive. Because of the realization of   fluorescence conversion with a narrow luminescent bandwidth, conventional phosphors can also be realized. For example, KSF:Mn is a low-cost, narrow-bandwidth phosphor option. Although KSF:Mn faces stability problems, the stability of QD is worse than that of KSF:Mn.


Getting a high-reliability QD film is not easy. Because QD is exposed to water and oxygen in the environment in the atmosphere, it quickly quenches and the luminous efficiency drops dramatically. The water-repellent and oxygen-proof protection solution of QD film, which is widely accepted at present, is to mix the QD into the glue first, and then sandwich the glue between two layers of water-proof and oxygen-proof plastic films to form a “sandwich” structure. This thin film solution has a thin thickness and is close to  the original BEF and other optical film characteristics of the backlight, which facilitates production and assembly.


In fact, QD, as a new luminous material, can be used as a photoluminescent fluorescent conversion material and can also be directly electrified to emit light. The use of the display area is far more than a way of QD filmFor example, QD can be applied to a MicroLED  as a fluorescence conversion layer to convert blue light or violet light emitted from an uLED chip into monochromatic light of other wavelengths. Since the size of the uLED is from a dozen micrometers to several tens of micrometers, and the size of the conventional phosphor particles is a minimum of a dozen micrometers, the particle size of the conventional phosphor is close to the single chip size of the uLED and cannot be used as the fluorescence conversion of the MicroLED. material. QD is the only choice for fluorescent color conversion materials currently used for the colorization of MicroLEDs.


In addition, the CF in the LCD cell itself acts as a filter and uses a light-absorbing material. If the original light-absorbing material is directly replaced with QD, a self-luminous QD-CF LCD cell can be realized, and the optical efficiency of the TFT-LCD can be greatly improved while achieving a wide color gamut.


In summary, quantum dots (QDs) do have a very broad application prospect in the display area. At present, the so-called "quantum- dot TV" adds a QD film to the conventional TFT-LCD backlight source, which is only an improvement of LCD TVs and has not fully utilized the advantages of QD. According to the forecast of the research institute, the display technology of the light color gamut will  form a situation in which high, medium and low grades and three kinds of solutions will coexist in the coming years. In middle and low grade products, phosphors and QD film form a competitive relationship. In high-end products, QD-CF LCD, MicroLED and QDLED will compete with OLED.