Theoretical Research on Intermolecular Hydrogen-Bond Contribution to the Long-Lived Room-Temperature Phosphorescence in Isomerism Crystals

In long-lived room-temperature phosphorescence (RTP) materials, intermolecular interactions have been increasingly acknowledged to play crucial roles, since more and more works have proved their important role in stabilizing the triplet excitons. Herein, we mainly focus on the intermolecular hydrogen bonds and will present a computational study on their regulation of the RTP lifetime of isomer molecules in crystal form and polymorphs. The hydrogen bond is found to have a corresponding relation with phosphorescence lifetime, i.e., an isomerism crystal with a longer RTP lifetime has a larger intermolecular hydrogen-bond contribution. Further investigation on the radiative and nonradiative transition processes illustrates that hydrogen bonds have a considerable impact on the phosphorescent radiative decay rate kp, while nonradiative processes play a weak role in regulating the RTP lifetime in these crystals. Thus, the crystals with a higher intermolecular hydrogen-bond contribution could obtain a longer lifetime mainly by reducing kp. This research may supply a facile way to achieve a long phosphorescence lifetime through enhancing intermolecular hydrogen-bond contribution.