Quantum dots have a unique characteristic: whenever they are stimulated by light or electricity, they will emit colored light, and the color of light is determined by the composition materials, size and shape of quantum dots. Generally, the smaller the particle, the longer the absorption time, and the larger the particle, the longer the absorption time. Quantum dots with a size of 2 nm can absorb long-wave red and display blue, while quantum dots with a size of 8 nm can absorb short-wave blue and display red. This feature enables quantum dots to change the color of light emitted by a light source.
Quantum dot display technology has been fully upgraded in color gamut coverage, color control accuracy, red, green and blue purity. It is regarded as the commanding height of global display technology, and it is also a display technology revolution that affects the whole world. Samsung, LG, Apple and other companies have indicated that they are actively promoting the research and development of quantum dot display technology, while Amazon, Asus and other companies have also adopted quantum dot technology to improve the image quality of their products to varying degrees. With TCL taking the lead in releasing quantum dot TV, the international quantum dot display camp has begun to take shape.
According to the authoritative test data released by Liu Zhigang, deputy general manager of the National Center for Quality Supervision and Inspection of Radio and Television Products, under NTSC standards, the color gamut of ordinary LED TVs is only 72%, the color gamut of the first generation of high-definition TVs is only 82%, the color gamut of the second generation of high-definition TVs is about 96%, and the color gamut coverage of quantum dot TVs is as high as 1 10%.
After 2000, scientists began to explore the possibility of using quantum dots for display. However, the comprehensive performance of QLED, such as efficiency, service life and processing technology, is far from people's good expectations.
With the deepening of QLED research by scientists, more and more progress has been made in the process of industrialization. Today's quantum dots usually take semiconductor elements and metal compounds as the core and are covered with a layer of tiny particles of other materials. So, what is quantum dot display?
Quantum dots are quasi-zero dimensional nanocrystals with a particle size of 2~ 10 nm. When stimulated by electricity or light, quantum dots will emit high-quality monochromatic light of different colors according to their diameters. The so-called Qled LCD screen is a new LCD screen with quantum dot film inserted between the blue LED backlight and the LCD panel. Quantum dot films will produce sharp blue-green red true color white light under the excitation of LED blue light, and QLED is even considered as the best scheme to improve the color gamut value of color TV in the future. Authoritative test data show that under the NTSC standard, the color gamut NTSC ratio of ordinary LED TV is only 72%, and LCD TV products equipped with QLED backlight (referred to as QLED TV) can achieve 1 10% color gamut coverage. At the same time, Jason Hart Rafe, CEO of Nanosys, once said in an interview that QLED has no size limit and can be used on TV screens over 80 inches or on small screens.
In the time dimension, QLED has been the third generation of innovative technology of light emitting diode (LED). The first generation is the well-known blue LED device (GaN LED), combined with rare earth phosphors. Although it is more energy-saving than incandescent lamp, its preparation process is quite strict, which affects the product cost. The second generation is organic LED, which was born in the late 1970s. Its manufacturing method is based on vacuum thermal evaporation, which has been applied to small-size screens such as mobile phones and products that do not need to be lit all the time. However, the luminescent center of such devices is organic molecules, and the product life and yield are unstable.
China does not lag behind other countries in technological research. The research group of Jin Yizheng, the State Key Laboratory of Silicon Materials of Zhejiang University, cooperated with the research group of Peng Xiaogang, and reported a kind of light-emitting diode with multilayer quantum dots prepared by solution method.
Its preparation method is based on the solution process with low cost and large-scale production potential, and its comprehensive performance exceeds all known red light devices with solution process, especially the service life under the condition of using brightness is improved to the practical level of 6,543,800 hours. Peng Xiaogang revealed that "the next step will be to develop other colors of high-performance QLED".
Quantum dots (QDs) are composed of zinc, cadmium, selenium and sulfur atoms. They are nano-materials with a crystal diameter of 2- 10 nm. They have unique photoelectric characteristics. After photoelectric stimulation, they will emit different colors of pure monochromatic light according to the diameter of quantum dots, which can change the color of the light source. Quantum dots can form a thin film on the LED backlight of LCD TV, and can emit full-spectrum light under the irradiation of blue LED, so as to adjust the light and fine-tune the backlight, thus greatly improving the color gamut performance and making the colors more vivid.