Simultaneously Enhancing Efficiency and Lifetime of Ultralong Organic Phosphorescence Materials by Molecular Self-Assembly

Metal-free organic phosphorescence
materials are of imperious demands
in optoelectronics and bioelectronics. However, it is still a formidable
challenge to develop a material with simultaneous efficiency and lifetime
enhancement under ambient conditions. In this study, we design and
synthesize a new class of high efficient ultralong organic phosphorescence
(UOP) materials through self-assembly of melamine and aromatic acids
in aqueous media. A supramolecular framework can be formed via multiple
intermolecular interactions, building a rigid environment to lock
the molecules firmly in a three-dimensional network, which not only
effectively limits the nonradiative decay of the triplet excitons
but also promotes the intersystem crossing. Thus, the supermolecules
we designed synchronously achieve an ultralong emission lifetime of
up to 1.91 s and a high phosphorescence quantum efficiency of 24.3%
under ambient conditions. To the best of our knowledge, this is the
best performance of UOP materials with simultaneous efficiency and
lifetime enhancement. Furthermore, it is successfully applied in a
barcode identification in darkness. This result not only paves the
way toward high efficient UOP materials but also expands their applications.