You joined NAIST as an assistant professor and launched a new research topic into the development of room-temperature phosphorescence materials that absorb light energy and emit phosphorescence with high efficiency. Phosphorescence, which is used in organic EL elements, emits light for longer periods of time than fluorescence that emits light using a similar mechanism. On top of that, its energy-saving properties are attracting attention because of the high energy utilization efficiency. With what ideas do you tackle research?

Fluorescence and phosphorescence are phenomena in which molecules absorb light, are promoted to excited states, and emit light as they return to the ground state. These excited states are classified into singlet and triplet states depending on the electron spin configuration. Phosphorescence occurs when an electron initially excited to a singlet state undergoes a spin flip to reach a triplet state and then returns to the ground state while emitting light. Since the transition from a triplet excited state to the ground state involves a spin flip, phosphorescence is characterized by a longer lifetime than fluorescence. In typical phosphorescence, when a molecule absorbs light, it is first excited to a singlet state and then transferred to a triplet state through multiple pathways. During this process, energy loss occurs, leading to reduced emission efficiency. Therefore, my focus is on a previously unexplored pathway in which molecules are directly excited from the singlet ground state to the triplet excited state. I believe that achieving such direct excitation will enable more efficient phosphorescence. Although this phenomenon is considered theoretically possible, there have been few experimental confirmations, which makes this research very challenging.