Researchers at the Laboratory of Low-Carbon Chemical Technologies at the NSU Natural Sciences Department (ORËL Research Lab) are developing materials with an afterglow effect based on organic molecules. Head of the Laboratory Evgeniy Mostovich described their work,
In the Laboratory we study organic light-emitting materials. One of our areas of research is materials with an afterglow effect. After being exposed to light for some time, these materials are then capable of emitting light themselves for a few seconds. We have known about inorganic materials with these properties for a very long time. However, most of them contain heavy metals, the presence of which causes a phosphorescent effect. In our work, we use a completely different approach, we abandoned heavy metals in favor of organic molecules for less toxicity and greater availability. Using a variety of organic molecules, we tailor the system to make the material glow longer and more efficiently. This approach allows us to completely control the properties by varying the structure of the molecules used and, depending on the task, to specifically obtain the necessary materials with the desired properties.
Currently, NSU scientists have created a material with a very high afterglow quantum efficiency (>70%). In this material the accumulation of light radiation is almost equal to its re-emission with a very effective contribution to the afterglow, the duration reaches up to three seconds. For organic materials this is quite long, but Laboratory specialists intend to increase its duration. To do this, using various methods of time-resolved spectroscopy, they study the processes occurring in materials with afterglow over various periods of time from the moment of irradiation. Depending on the structure of the molecules, their concentration and the type of matrix used, they determine ways to optimize this system, increase its efficiency, and increase the afterglow time.
Researchers have studied various systems and found out which groups of atoms in organic molecules increase its duration, and which, reduce it. Now they are developing approaches to the targeted synthesis of organic molecules that will have either a longer or shorter afterglow time.
Another objective the researchers set for themselves is to create an afterglow palette. Currently, the afterglow materials created in the ORËL Research Lab glow yellow, green, and blue. They have plans to supplement this color range with red and orange. This may be useful for bioimaging laboratory studies, for example, of living tissues. In this case, the dye can be delivered on the basis of specially prepared nanoparticles and can be used to stain tissue cells that need to be monitored during various processes.
Another area of application for these new materials is cryptography. The afterglow effect can be used to protect information, documents, or a personal signature.
