In recent years, organic EL is expected as a new display and surface light source for lighting, which has features such as light weight, flexibility, high brightness, high definition, and low power consumption.However, the phosphorescent material for increasing the luminous efficiency is costly and disadvantageous in terms of resources.Therefore, it is desired to develop a next-generation organic EL material with high efficiency and low cost.

　This time, both of them conducted research on organic molecules designed and developed by Kyushu University in order to elucidate their emission mechanism in detail using pump-probe transient absorption spectroscopy.In particular, we focused on the types (excited species) and energies of singlet and triplet states of each molecule, which have been overlooked in previous studies. When the amount of organic EL emitted from eight types of molecules was examined, it was found that all the molecular groups that strongly emit TADF are para-forms, suggesting that this molecular structure is involved in TADF emission. ..

　As a result, it is thought that it will be possible to search for and produce higher-performance TADF molecules that have high luminous efficiency and material durability in various emission colors. The realization of next-generation optical devices is expected.

　In the future, we will observe the excited state conversion process of TADF molecules in more detail and construct a systematic design guideline for TADF molecules in which the excited state conversion occurs with high efficiency.In addition, these findings will be fed back to the design of TADF molecules to support the development of TADF materials that have both high luminous efficiency and durability.