Dynamic Reversible Full-Color Piezochromic Fluorogens Featuring Through-Space Charge-Transfer Thermally Activated Delayed Fluorescence and their Application as X-Ray Imaging Scintillators

Thermally activated delayed fluorescence (TADF) emitters featuring through-space charge transfer (TSCT) can be excellent candidates for piezochromic luminescent (PCL) materials due to their structural dynamics. Spatial donor-acceptor (D-A) stacking arrangements enable the modulation of inter- and intramolecular D-A interactions, as well as spatial charge transfer states, under varying pressure conditions. Herein, we demonstrate an effective approach toward dynamic reversible full-color PCL materials with TSCT-TADF characteristics. Their single crystals exhibit a full-color-gamut PCL process spanning a range of 170 nm. Moreover, the TSCT-TADF-PCL emitters display a unity photoluminescence quantum yield, and show promising application in X-ray scintillator imaging. Through-space charge-transfer thermally activated delayed fluorescence (TADF) emitters demonstrate dynamic reversible piezochromic luminescent (PCL) behavior by the modulation of inter/intramolecular donor-acceptor interactions, and their single crystals exhibit full-color PCL process spanning a wide range of 170 nm at high pressure. These TADF emitters also show radioluminescence, with promising potential in X-ray scintillator imaging. image