Prolonging the lifetime of ultralong organic phosphorescence through dihydrogen bonding

Abstract

Developing metal-free organic phosphorescence materials with ultralong lifetimes is a long-standing concern in optoelectronics. Herein, for the first time, we report a concise chemical strategy to prolong the lifetime of ultralong organic phosphorescence (UOP) via dihydrogen bonding. On slighlty tailoring alkyl chain in their molecular structure, the phosphorescence lifetime of the as-prepared triazine derivatives increased by 25% (to 788 ms) under ambient conditions. Moreover, tunable ultralong luminescence was realized with various excitation wavelengths. Significantly, a white persistent luminescence was obtained, for the first time, when the excitation at 300 nm was switched off. Combining theoretical simulations and single crystal analysis, we conclude that the polar dihydrogen bonds of C–H⋯H–N in the DCzNT crystal play a critical role in increasing the lifetime of the UOP. In addition, the ultralong phosphors were successfully applied to anti-counterfeiting of a currency bill. These results can offer a new platform towards tuning the lifetime of UOP and expanding the scope of organic phosphorescence materials and their optoelectronic applications.