Fused Framework: Visible‐Light‐Excited, Robustly Time‐Dependent Multicolor Phosphorescence From a Dispersed Organic Molecule

ABSTRACT Achieving persistent room‐temperature phosphorescence (RTP) with a time‐dependent afterglow in organic systems is highly attractive for superior optoelectronic applications, yet remains challenging in stability and visible‐light excitation. Herein, we present an efficient strategy of ‘fused framework’ to design a phosphor (TpPTZ) integrated with a triplet‐stabilizing unit and a bending‐vibrational conformation via a shared phenyl ring. It realizes visible‐light excited, robust time‐dependent afterglow when dispersed in polar polymer matrixes. With an ultralow doping content of 0.1 wt.%, the afterglow color switches from yellow to green within seconds, even at an elevated temperature of 343 K. Studies reveal that the dual afterglow originates from two triplet states of the dynamic conformations of TpPTZ. As the bending dihedral angle ( θ Tp‐ph ) increased, the energy levels of singlet (S 1 ) and triplet (T 1 ) excited states intersect at θ Tp‐ph of 33° and then invert from S 1 < T 1 to S 1 > T 1 . Thus, a strong yellow afterglow occurs at a small θ Tp‐ph of ∼30°, and a weak green afterglow arises at θ Tp‐ph larger than 33°. This work demonstrates a new strategy of ‘fused framework’ for combining new functions into organic persistent RTP molecules, promoting their further diversification of functional properties for optoelectronic and biological applications.