The
insufficiency of effectively activating purely organic phosphorescence
has greatly limited the development and application of purely organic
phosphors. Herein, amorphization of purely organic phosphors into
carbon dots (C-dots), namely, amorphization strategy, was designed
for activating matrix-free room-temperature phosphorescence (RTP)
of C-dots. Using citric acid and 2,4,6-trihydrazinyl-1,3,5-triazine
(THT) as precursors, the obtained C-dots reserved the ordered structure
similar to a THT single crystal in the interior of C-dots. The doped
triazine overing is critical for RTP; it not only provides the n–π* transition center but also plays a key
role in facilitating the intersystem crossing. The weak interactions
among THT molecules, such as π···π
stacking and hydrogen bond interactions, and the hydrogen bond among
functional groups in the interior of C-dots, together with the steric
hindrance formed by polymer-like structures of C-dots, served as matrices
to embed and immobilize the emissive center, resulting in the afterglow
with a lifetime of 66.4 ms. C-dot-based RTP was successfully used
for digital encryption, information protection, and antibacterial
protection. Most importantly, the universality of the amorphization
strategy provided a simple and advantageous pathway for the activation
of C-dot-based matrix-free RTP.