Single-Component Molecular Dual Persistent Room Temperature Phosphorescence from Low- and High-Lying Triplet States

Single molecules with dual persistent luminescence are very rarely explored, in spite of their emerging use in frontier optoelectronic applications. Here, a pure organic phosphor of tris(4-chlorophenyl)phosphine oxide (CPO) possessing a large energy gap between the lowest excited triplet (T-1) and higher excited triplet (T-2) states is reported, which can emit dual persistent room-temperature phosphorescence (RTP) from low- and high-lying triplet excited states. The femtosecond transient absorption experiments and theoretical calculations reveal that the excitons to the T-1 and T-2 states are populated through different pathways. As a result, the distribution of the triplet excitons can be efficiently manipulated by using different excitation energy, and tunable afterglow colors from green to yellow can be achieved. Furthermore, the CPO molecule is successfully applied in the fabrication of high-level anti-counterfeiting tags and flexible 3D objects with curling properties. From these initial discoveries, it is expected that triphenylphosphine derivatives, with their rich chemistry of core-substitution, can provide infinite opportunities in the expansion of organic molecules with high-lying persistent RTP.

Automated summary

A pure organic phosphor with dual persistent luminescence is reported, which can emit different afterglow colors by manipulating the excitation energy. The molecule also shows potential applications in anti-counterfeiting tags and flexible 3D object fabrication.