New Dibenzophenazine-Primarily based Liquid Crystals for Use in Optoelectronics, Photo voltaic Panels

New liquid crystals based on dibenzophenazine, which were synthesized and investigated by a professor at RUDN University together with his Indian colleagues, could be used in solar modules and in optoelectronics.

Photo credit: RUDN University.

The study results were published in the Journal of Molecular Liquids.

Liquid crystals are considered to be the intermediate phase between a solid body and a liquid. Although they are arranged similarly to normal crystals, they flow at the same time like liquids. It is this dual function that enables them to be used in organic LCDs and LEDs.

In contrast to other liquid crystals, discotic (DLC) have the ability to assemble themselves into organized structures. This makes them very promising for industrial electronics, especially for the manufacture of displays.

Discotic liquid crystals are interesting because of their ability to form self-organized, ordered columnar structures. In such structures, an electrical charge can move along the column, which makes them useful for optoelectronic devices such as organic LEDs, organic field effect transistors (OFET), photoelectric solar elements and sensors.

Viktor Belyaev, Professor and Doctor of Technical Sciences, Faculty of Mechanics and Mechatronics, RUDN University

DLCs ​​consist of disc-shaped molecules arranged in columns. An aromatic ring (which is a cyclic organic fragment) surrounded by chains of other organic fragments is in the center of each disk.

The aromatic center allows a DLC to move a charge along the axis of a column. Prof. Belyaev has synthesized discotic liquid crystals with an aromatic compound called dibenzophenazine in the center.

For the chains that surrounded it, the researchers tried using three different types of fragments. The molecular structure of the latest DLCs has been analyzed using spectral, X-ray diffraction and elemental analysis. In addition, the researchers tested the three groups of DLCs in several experiments.

The experiments showed that alkoxythiol chains increased the polarity of the molecules in liquid crystals, thereby improving the internal structure of the columns and making them more uniform. All new DLCs could withstand temperatures of up to 330 ° C.

However, the crystals that contained smaller molecules (those whose aromatic center is surrounded by alkylthiols) tend to lose their intermediate state and change from liquid crystal to liquid form at lower temperatures (55.1 ° C) than the crystals of the two other groups. This is due to the size of the molecules in the pillars: the larger they are, the more stable the liquid crystal state.

The new discotic liquid crystals could play an important role in organic optoelectronic components and solar modules.

Viktor Belyaev, Professor and Doctor of Technical Sciences, Faculty of Mechanics and Mechatronics, RUDN University

Journal reference:

Jacob, L. et al. (2020) Synthesis, thermal and photophysical studies of π-elongated discotic liquid crystals based on dibenzophenazine. Journal of Molecular Liquids.


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