Studies on the Luminescence Property of Yttrium-Based Metallofullerenes

Endohedral metallofullerenes (EMFs) exhibit various properties due to their multiple combinations between internal metals and outer carbon cages. Among them, yttrium-based metallofullerenes have attracted much attention due to their luminescence properties. For example, Y3N@C80 is distinguished by its photoluminescence (PL) properties with a small energy gap between the lowest singlet states (S1) and the triplet excited states (T1) in Y3N@C80, allowing reverse intersystem crossing (RISC) of T1→S1 and resulting in thermally activated delayed fluorescence (TADF). In addition, the PL intensity, lifetime, and quantum yield (QY) of Y3N@C80 all depend on the molecular structure and surrounding environment. Typically, modulation of the PL properties can be achieved by replacing the yttrium metal inside the carbon cage as well as by modifying the carbon cage externally. Here, we focus on the luminescence properties of yttrium-based metallofullerenes, summarize recent research advances, and predict their future development.