What They Say
SciTechDaily reported on research published in the journal Dyes & Pigments from the Ural Federal University in Russia that worked on the inclusion of cyanogroup compounds in fluorophores to considerably boost the efficiency of OLEDs. Egor Verbitskiy said:
“We modified the pyrazine-based push-pull system with cyanogroup and studied how this affected the photophysical properties of the fluorophores and the performance of OLEDs based on it. The phenomenon of TADF, due to the peculiarities of the structure of the initial substance, did not arise, although there are prerequisites for it. However, it turned out that the introduction of a cyanogroup intensifies intermolecular interactions, as a result of which not individual molecules but complexes of molecules begin to fluoresce.
As a consequence, the increase in luminescence intensity was from 2.4 to 20 times, and the brightness of the emitted light was up to 75 times. Such results were shown by several prototype devices made by our colleagues and co-authors from Tomsk State University. It is also important that we used inexpensive and accessible compounds in our research.
A study of the properties of a wide range of 1,4-diazine-based push-pull systems revealed that the addition of a benzene ring to the pyrazine cycle can improve the efficiency and brightness of the OLEDs produced. At the same time, some of the OLEDs tend to exhibit thermally activated delayed fluorescence (TADF). This is evidenced by the increase in fluorescence lifetime.
Reference: “Impact of an ortho-cyano group on photophysical properties and performance of OLEDs based on D-A–A type pyrazine push-pull system” by Egor V. Verbitskiy, Ruslan M. Gadirov, Lubov G. Samsonova, Konstantin M. Degtyarenko, Alexander E. Kurtcevich, Elizaveta V. Sapozhnikova, Margarita V. Medvedeva, Tatyana S. Svalova, Alisa N. Kozitsina, Gennady L. Rusinov, and Valery N. Charushin, 12 September 2022, Dyes and Pigments.
DOI: 10.1016/j.dyepig.2022.110716
What We Think
To be honest, this article is above my paygrade for OLED chemistry, but those of our readers that are in that area may better be able to decide if this is significant! If you do think so, feel free to let me know! (BR)
One of the assembled organic LEDs based on push-pull systems containing cyanopyrazine fragments. Credit: Ruslan Gadirov
