Metal-free organic molecules exhibit highly efficient room-temperature phosphorescence

According to new research by chemists at Osaka University, metal-free organic 3-bromo-2-thienyl diketones exhibit rapid and highly efficient room-temperature phosphorescence with high color purity under various conditions.

“Phosphorescence is a valuable optical function used in applications such as OLEDs and cancer diagnosis,” said Yosuke Tani, a chemist at Osaka University, and colleagues.

“Until now, achieving high-efficiency phosphorescence without using rare metals such as iridium and platinum has been a major challenge.”

“Phosphorescence, which occurs when a molecule transitions from a high-energy state to a low-energy state, often competes with non-radiative processes where the molecule loses energy as heat,” they added.

“This competition can lead to slow phosphorescence and lower efficiency.”

“Although previous research has shown that incorporating certain structural elements into organic molecules can accelerate phosphorescence, these efforts have not matched the speed and efficiency of rare metal-based materials.”

“Our breakthrough in the field of thienyl diketones represents a significant advance in this field.”

Dr. Tani and his co-authors were able to observe efficient narrow-band phosphorescence at room temperature from 3-bromo-2-thienyl diketones in solutions, amorphous polymer matrices, and crystalline solids.

“We discovered these molecules by chance and initially did not understand why they demonstrated such superior performance,” Dr. Tani said.

“However, as our research progressed, we began to connect the pieces of the puzzle and deepen our understanding.”

“Our research has provided a better understanding of the mechanism behind the performance of the molecules than any other organic phosphorescent material.”

“Nevertheless, we believe there is still much to explore and we are excited about its potential applications.”

“This research provides new design guidelines for the development of organic phosphorescent materials that do not depend on rare metals, offering the potential to outperform and replace these materials in various applications,” the authors conclude.

“These results promise significant advances in the fields of OLEDs, lighting and medical diagnostics, among others.”

The discovery is reported in an article in the journal Chemical sciences.

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Yosuke Tani et alFast, efficient, and narrow-band room-temperature phosphorescence from metal-free 1,2-diketones: rational design and mechanism. Chemical sciencesPublished online June 3, 2024; doi: 10.1039/D4SC02841D