Reversible and Continuous Color-Tunable Persistent Luminescence of Metal-Free Organic Materials by “Self”-Interface Energy Transfer

Persistent
luminescence from metal-free organic materials is attractive
for their ultralong exciton lifetimes. Color-tunable persistent luminescence
from single-component organic materials is fascinating but still challenging.
By utilizing an efficient approach of “self”-interface
energy transfer (IET), the persistent luminescence color of an organic
phosphor (CTXO) can be reversibly and continuously tuned by external
physical stimuli. Its color circularly changes between green (lifetime
= 0.24 s) and deep-yellow (lifetime = 0.10 s) when CTXO is repeatedly
triggered with thermal annealing and mechanical grinding. Self-IET
from the crystalline part (donor), which exhibits persistent room-temperature
phosphorescence, to the amorphous part (acceptor) inside its semicrystal
during these treatments is found to be the key exciton process for
such novel color modulation. This also provides opportunity for designing
stimuli-responsive smart materials with controlled persistent luminescence.