Acquiring Charge‐Transfer‐Featured Single‐Molecule Ultralong Organic Room Temperature Phosphorescence via Through‐Space Electronic Coupling

Abstract

AbstractAlthough long‐lived triplet charge‐transfer (3CT) state with high energy level has gained significant attention, the development of organic small molecules capable of achieving such states remains a major challenge. Herein, by using the through‐space electronic coupling effect, we have developed a compound, namely NIC‐DMAC, which has a long‐lived 3CT state at the single‐molecule level with a lifetime of 210 ms and a high energy level of up to 2.50 eV. Through a combination of experimental and computational approaches, we have elucidated the photophysical processes of NIC‐DMAC, which involve sequential transitions from the first singlet excited state (S1) that shows a 1CT character to the first triplet excited state (T1) that exhibits a local excited state feature (3LE), and then to the second triplet excited state (T2) that shows a 3CT character (i.e., S1 (1CT)→T1 (3LE)→T2 (3CT)). The long lifetime and high energy level of its 3CT state have enabled NIC‐DMAC as an initiator for photocuring in double patterning applications.