Ultralong Room Temperature Phosphorescence through Both Space Confinement and Long-Range Charge Migration

Doping guest materials into host materials with a confined space to suppress nonradiative decay is an effective strategy for achieving room-temperature phosphorescence (RTP). However, constructing host-guest doped materials with ultralong RTP (URTP) is still challenging. Herein, by embedding three coumarin derivatives into boric acid via one-step heat treatment, the URTP material with an afterglow lasting up to 60 s, a phosphorescence lifetime of 1.59 s, and a quantum yield of 18.14% was successfully prepared. Experimental results show that the dense 3D boron oxide network formed after heat treatment, along with the B-O covalent bonds and O→B coordination bonds between the host and guest, effectively suppresses nonradiative transitions through both physical and chemical confinement. More importantly, the oxygen vacancy defects formed in the doped material during heat treatment, combined with the charge-separated states generated in the guest molecules upon irradiation, together facilitated the long-range charge migration process. In addition, the charge recombination is accompanied by long-lived phosphorescence emission. Finally, the prepared URTP materials exhibit potential applications in the encryption and decryption of information in security fields.