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TSU physicists are creating blue diodes based on circulenes

Tatyana Arseneva

TSU physicists have solved the problem of creating blue organic light-emitting diodes (OLEDs), which are needed to create displays for phones, televisions, tablets, and other devices using cheap materials—hetero[8]circulenes. Blue diodes on organics remain the last technically complex element for the RGB structure (red-green-blue). The OLED technology is much cheaper and more economical than LCD (liquid crystal) technology; also these OLEDs are easy to recycle.

Tomsk physicists were able to create light-emitting diodes based on heterocirculenes—organic molecules that are highly stable and have good luminescence. Scientists have developed a technology to create them, including blue OLEDs, which, unlike the red and green, are problematic to produce.

- The technology of creating red and green OLEDs is almost perfected, but the creation of blue OLEDs for RGB layers is still an urgent task,- explains Rashid Valiev, associate professor at the Faculty of Physics. - Here we need to search for stable substances that shine effectively in the blue range at low voltages. We have proposed molecules of circulenes.

The feature of the work is that first, scientists used the methods of quantum chemistry to predict the luminosity of the selected molecules, and then they synthesized.

- In fact, in 2016, we predicted the luminescent properties of these circulenes using quantum chemistry methods. Later our colleagues from the University of Copenhagen were able to synthesize them—continues Rashid Valiev. - And this year we were able to create an OLED in Tomsk. In fairness, it must be said that at first, white OLEDs were also made on them because it was technically difficult to create blue ones. But we solved this technical problem in Tomsk by removing excimer radiation.

White OLEDs are used in the manufacture of luminaires: with low power supply, they are highly efficient. Diodes emit light and at the same time almost do not heat up; moreover, they make it possible to illuminate a much larger surface compared to incandescent lamps due to the controlled directivity of the radiation.

Another result was that the Tomsk group significantly improved its design algorithm, which, in principle, makes it possible to read and predict the luminescent properties of almost any molecule.

In the future, scientists are planning to improve the technology of producing blue OLEDs on the circulenes for flexible displays.

Provided by Tomsk State University