Your location:

Popular Science: Why can the toxic element cadmium be used in quantum dot technology?

Categories:Company News
Author:
Origin:
Time of issue:2016-05-12
Views:0

(Summary description)A few days ago, Hisense Electric and QD Vision, a global leader in quantum dot display technology, launched an energy-saving and emission-reduction industry initiative in Beijing. As one of the essential household appliances in the home, the power consumption of TV is often ignored. Especially after the traditional CRT TVs fade out of the market, people feel that TVs no longer consume much electricity. In fact, different types of TV sets have different energy-saving effects. So why can quantum dot technology save energy?





Popular Science: Why can the toxic element cadmium be used in quantum dot technology?

Categories:Company News
Author:
Origin:
Time of issue:2016-05-12
Views:0

Information

Guangming Net News Recently, Hisense Electric and QD Vision, a global leader in quantum dot display technology, launched an energy-saving and emission-reduction industry initiative in Beijing. As one of the essential household appliances, the power consumption of TV is often ignored. Especially after the traditional CRT TVs fade out of the market, people feel that TVs no longer consume much electricity. In fact, different types of TV sets have different energy-saving effects. So why can quantum dot technology save energy?

Display technology is an important branch in the history of technological development. It is not only a product of scientific development, but also constantly feeding back the progress of science. After years of development, display technology has been greatly improved, including the well-known CRT display technology, plasma display technology, and LCD display technology, among which plasma display technology and LCD display technology can be classified as FPD (flat panel display).

From the current market share, FPD has completely surpassed CRT. In our lives, we can see that computer monitors, color TV screens and other equipment adopt FPD technology. This can actually be understood as a display technology revolution, that is, FPD technology has replaced it. CRT technology.

Although FPD technology has become the mainstream of the current display field, as far as FPD itself is concerned, the display technology it contains has not developed in a balanced manner, and the LCD technology is far beyond plasma technology. In comparison, LCD displays have the characteristics of low voltage, low power consumption, high reliability, and low cost, and can be directly matched with CMOS integrated circuits.

However, although LCD display technology has many advantages, it is not perfect. A very critical shortcoming is its low color gamut range, that is, the color range that can be presented is very limited. The color gamut of an ordinary LCD display is generally only 72% NTSC. This is obviously not enough in today's increasingly demanding scientific research and life fields.

In order to solve this problem, quantum dot technology came into being. First come to popular science, what is Quantum Dots (Quantum Dots)? Quantum dots are man-made semiconductor nanomaterials. When stimulated by light, quantum dots emit very pure colored light. The backlight using quantum dot materials is the purest color backlight at present. In short, It is a kind of engineering nano material that can emit pure color light, which will bring richer extraordinary colors to the display.

Quantum dots, as a new nanomaterial with unique light characteristics, can accurately and efficiently convert high-energy blue light into red and green light. Quantum dots can form a thin film on the LED backlight of the LCD display and illuminate it with blue LEDs. It can emit full-spectrum light, and by finely adjusting the backlight, the color gamut performance can be greatly improved, and the colors are more vivid.

Quantum dot display technology has been fully upgraded in various dimensions such as color gamut coverage, color control accuracy, red, green and blue color purity, and is regarded as the commanding height of global display technology, as well as a display technology revolution affecting the world. Compared with traditional LCD displays, the color gamut of quantum dot displays can reach 110%.

QD Vision, a company cooperating with Hisense, was founded in 2005 in the United States. Many employees come from MIT. In 2013, it launched the first Color IQ quantum dot display and currently has the world's largest quantum dot manufacturing plant.

It is understood that ColorIQ can increase the color performance of LCD TVs by 50% and achieve more than 100% NTSC color gamut coverage of LCD TVs. At the same time, its price is much lower than the cost of film, and its energy consumption is 25% lower than that of OLED.

At present, many home appliance manufacturers, including Hisense, TCL, Konka, Sharp, LG, Changhong, Philips, Samsung, and Skyworth, have begun to apply quantum dot technology.

Dr. Jennifer Colegrove, CEO of Touch Display Research, predicts that by 2025, 60% of TVs will have quantum dots and 51% of displays will use quantum dot technology.

Today’s quantum dots are usually made of two compounds: cadmium selenide (CdSe) and indium phosphide (InP). Investigations by the American Cancer Society and three federal government agencies have shown that indium phosphide is highly carcinogenic. Experiments in rats have shown It will cause a "quite high" incidence of lung cancer.

Why can the toxic substance "cadmium" be used in quantum dot technology, and it is safer? Studies have shown that cadmium, as a high-melting, non-volatile metal, has stable performance at room temperature. Although the element cadmium is poisonous, the compound cadmium selenide used in quantum dots is not poisonous and will not cause health problems after being made into display devices. The REACH EU certification evaluates cadmium selenide and also believes that cadmium selenide should not be classified as a "health risk chemical."

First of all, quantum dots can convert the toxic element cadmium into safe and environmentally friendly cadmium selenide. The annual global output of cadmium is 30,000 tons. The production of quantum dot equipment can convert cadmium in the environment into non-toxic cadmium compounds and reduce environmental pollution. Second, once formed, cadmium selenide is difficult to decompose into separate cadmium and selenium. Therefore, cadmium selenide is not bioavailable, and unlike cadmium, it does not accumulate in the body. Finally, the content of cadmium selenide used in the display is very low, and the general cadmium selenide display only contains 1.5 mg of cadmium.

In practical applications, cadmium selenide quantum dots exist in a semiconductor shell, then sealed in a polymer matrix, and encapsulated in a glass tube (or "quantum dot fiber") in a TV or display backlight unit. In QD Vision's experiment, according to the toxic characteristic dissolution protocol that simulates the leaching of toxic chemicals (from TVs that may be improperly disposed of), the quantum dot optical device did not detect cadmium during the test. Therefore, to a certain extent, the cadmium selenide-based quantum dot technology display device does not have health risks.

Although this conclusion has been verified by experiments, in real life, the use of cadmium-based quantum dot materials is still restricted according to the European and American ROHS standards. However, the European and American ROHS standards also stipulate that there is an exemption when the cadmium content is less than 0.001%. Circumstances, and the optical components of the quantum dot technology developed by QD Vision are on the exemption list.

Related evaluations believe that the energy saved by a Color IQ TV throughout its life cycle can significantly reduce the amount of cadmium released into the environment. The cadmium content of 500 quantum dot TV sets is less than the cadmium content of an AA (size 5) NiCad battery.

In today's work and life, our requirements for display devices are becoming higher and higher, whether it is ultra-fine medical diagnosis, high-quality industrial modeling, excellent innovation and industrial design, or more realistic entertainment and audio-visual experience. The support of better display devices is needed, and today's mainstream display technologies can no longer meet these needs well.

The International Telecommunications Union (ITU) released a new specification code-named Rec.2020 in 2012. This is a specification for playback and display. It is the basis of the new ultra-high UHD Blu-ray specification. Its color gamut requirements are the current Twice the general standard. Companies including Intel, Netflix, Sharp, 3M, Google, Sony and Canon have announced that they will adopt this standard. However, none of the existing mainstream display technologies can reach this standard. The only feasible solution foreseeable is the development of quantum dot display technology.

Scan the QR code to read on your phone

Previous: Introduction to Quantum Dots

Next: Scientific Interpretation of Quantum Dot Display Technology

Previous: Introduction to Quantum Dots

Next: Scientific Interpretation of Quantum Dot Display Technology

Related information