DEVELOPING DISPLAYS: ACQUISITIONS FOR THE FUTURE

From bright red tomatoes and lush forests to the deep blue sea, natural objects and landscapes generally have very rich colors. However, the human eye sees only the color that remains after some part of white light has been reflected, while the rest is absorbed by the object in question. 

The intensity with which we see colors is largely dependent on how many individual colors of light strike our retinas. For example, the deep green color of a leaf consists not of a single shade of green, but of many green shades that are located close together in the visible spectrum. The principle is the same with other colors. All of the colors in the visible spectrum are found in white sunlight, ranging from the short-wave blue region at the top all the way to the long-wave red region at the very bottom.    

Nature is thus a step ahead of technology, which is forced to take the opposite approach. That scores a point for nature. However, Merck KGaA, Darmstadt, Germany is now getting involved in this process as well, because display manufacturers have to use technology to generate single visible colors. This, in turn, requires sophisticated materials, which Merck KGaA, Darmstadt, Germany is developing not only in its own research units, but also in cooperation with specialists. 

For example, the startup Qlight Nanotech, which was founded in 2009, has proved to be extremely inventive when it comes to the development of quantum materials. Consequently, Merck KGaA, Darmstadt, Germany acquired an interest in this Israeli company in 2012 and purchased the remaining stake in 2015.    

Quantum materials are tiny semiconductor crystals that reproduce the color spectrum of natural sunlight in state-of-the-art display technology. To do this, they convert blue light that shines on them into very clear shades of green and red. The size of the crystals determines the colors that are produced. A wide variety of colors can be generated by mixing the three very pure colors blue, green, and red.

Quantum physics makes this mechanism possible. According to this theory, tiny particles can only absorb certain energy levels. Consequently, the electrons inside an atom are not uniformly distributed throughout an electron cloud surrounding the atomic nucleus. Instead, the electrons are grouped in regular patterns around the center, like the apples in the crown of an apple tree. In their basic state, the electrons occupy lower energy levels. They can jump to higher states when they are excited — by light, for example. The amount of energy that the electrons absorb in this process depends on the wavelength of the light. The shorter the wavelength, the higher the energy. If the electrons drop back down to their original states, the same rule applies in reverse. The more energy the electrons release as they drop back down, the shorter the wavelength of light they emit.    

Quantum materials are unusual because their electrons generally do not drop back to their original states after optical excitation. Instead, they only drop to an interim state that is at a higher energy level than the original one. Because the electrons do not release all of the energy they have absorbed, the wavelengths of light they emit are longer than the wavelengths of blue light they absorbed. The emitted light shines green, yellow or red, depending on the size of the crystals in question. 

Quantum materials offer an additional benefit when they are used as a source of light in displays. In conventional displays, the colors blue, green, and red are filtered out of the original white light of the light source. A lot of light is lost in this process. Because quantum materials only generate the light that is needed for light mixtures, less light is absorbed by the color filters. This increases the display’s brightness and thus reduces electricity consumption. This property is becoming especially important for mobile devices.

Qlight Nanotech thus fits perfectly into the portfolio of
Merck KGaA, Darmstadt, Germany because the Israeli company is the world’s leading developer and manufacturer of liquid crystals for TV screens and laptop and smartphone displays. Merck KGaA, Darmstadt, Germany also supplies a wide range of additional products that are indispensable for the production of displays. They range from backlighting materials all the way to thin-film transistors that are used to electrically activate liquid crystals.    

In order to further strengthen and expand its market position, Merck KGaA, Darmstadt, Germany is making acquisitions in order to penetrate new segments. In 2014, for example, the company acquired the British company AZ Electronic Materials, one of the leading manufacturers of high-tech chemicals such as photoresists and dielectric materials, which are indispensable for the production of high-performance integrated circuits. “This is the first time we are supplying materials that are used not only by display manufacturers in production but also by processor manufacturers,” says Dieter Schroth, who is responsible for the strategic marketing of new technologies and applications within the Display Materials business unit. This is important “because it enables us to work together with our customers in new fields and develop the basis for new products that we cannot yet even foresee.”

A look back at the 1990s shows how fast displays can evolve. Until then, bulky cathode ray tubes were the standard technology for television sets and computer monitors. This technology was originally developed by the German physicist Karl Ferdinand Braun in 1897. Back then, flat liquid crystal displays (LCDs) with a size, color, and reaction time comparable to cathode ray tubes were still believed to lie far in the future. 

However, after the initial basic technological and production-related challenges were overcome, LCDs quickly established themselves in the market — often by means of new materials. Ever since this breakthrough, the industry has been continuously launching new innovations onto the market. One example of this is screens that enable viewers to see three-dimensional images by wearing special glasses or even without them. Another example is displays made of organic materials that can be printed over large areas on flexible lightweight substrates. Merck KGaA, Darmstadt, Germany now supplies the high-tech materials that are needed for both types of displays.