UrFU Chemists Create New Organic Materials for Lasers and Ultrathin Screens

09:05, January 20, 2021

The special structure determines the most efficient absorption and redistribution of energy

Chemists of the Ural Federal University and the Ural Branch of the Russian Academy of Sciences have synthesized new organic compounds that can be used in lasers and ultrathin screens. Together with physicists from Tomsk State University, scientists have constructed a prototype of an ultra-high resolution screen on the basis of these substances. The research was supported financially by the Russian Science Foundation.

More details on the work can be found in the Journal of Photochemistry and Photobiology A: Chemistry.

White light is a stream of electromagnetic waves with different energies: the shorter the wavelength, the higher the light energy. We see this world colored in all the colors of the rainbow due to substances that absorb, reflect and emit light with a certain energy. The molecular structure of the material of which an object is composed determines its interaction with light. Modern chemists are able to predict exactly how this will happen.

In addition to reflection and absorption, some compounds are capable of emitting light, or luminescence, under certain conditions. The molecules of such substances, after absorbing energy, convert it into radiation. In the early 1950s, French scientists discovered a special type of substance that can do this using electricity. Devices developed on the basis of this phenomenon are called organic light-emitting diodes. They are used to create displays in which you can customize each pixel separately. Such screens are capable of providing a higher resolution for image transmission than liquid crystal screens. Due to the fact that the pixels are supplied not with light, but with electricity, black pixels remain black and adjacent dots do not light up each other. OLED displays are also better at rendering color depth.

Russian chemists have synthesized two new compounds, which, in accordance with their structure and properties, are organic dyes. The molecules of the obtained substances contain nitrogen and sulfur atoms in the composition of closed pentagonal and hexagonal cycles, connected in a certain sequence. It is a special structure, that is, the mutual arrangement of atoms in molecules, that determines the most effective absorption and redistribution of energy. Both substances turned out to be capable of stable fluorescence (a special case of luminescence) in the temperature range from -196 to 20 ° C. Molecular structure plays an important role in the creation of dyes. The glow brightness of the obtained LEDs is determined not only by the thickness of the organic layer, but also by differences in the structure of molecules: the radiation of one of the substances when the same potential value was applied was three times more intense.

In addition to creating displays, the resulting organic dyes can be used to create lasers. An electrical impulse causes an avalanche reaction in the solution, which results in the generation of a beam of light with a specific wavelength. Usually, lasers use complex crystals or gases that operate in a narrow range of emitted light. With the help of the obtained dyes, sources are obtained in which, under certain conditions, it is possible to switch the color of the beam by varying the applied voltage.

“The dyes we have obtained are the result of many years of research in the field of chemistry of nitrogen-containing organic molecules. By working together with colleagues from other fields, we are unlocking the potential of these substances. The introduction of organic materials is the basis for the development of technologies that will become less energy-consuming and more productive in comparison with those based on the use of inorganic compounds,” explained Dr. Gennady Rusinov, associate professor of the Department of Organic Synthesis of the Ural Federal University.