Persistent Organic White‐Emitting Afterglow from Ultralong Thermally Activated Delayed Fluorescence and Room‐Temperature Phosphorescence

The current organic white light emission is unabiding and excited by UV light. This work presents the first ultralong organic room‐temperature white‐emitting crystal from 2,6‐di(carbazol‐9‐yl)benzonitrile that emits prompt blue light and delayed white light. Impressively, this white afterglow is nondiscoloring and exhibits high photoluminescence (PL) efficiency over 6% and ultralong lifetime over 900 ms and can be excited at wide wavelengths of 300–520 nm. Single‐crystal analysis and room‐ and low‐temperature PL reveal that this V‐type double D–A molecule can adopt different twisted conformations to pack together and form two kinds of ultralong room‐temperature afterglow crystals, and the vertical conformation can greatly reduce the energy gap between the lowest singlet and triplet states and prolong the reverse intersystem crossing to enable persistent and visible‐light excitable hybrid white‐emitting afterglow consisting of ultralong thermally activated delayed fluorescence and room‐temperature phosphorescence. 2,6‐Di(carbazol‐9‐yl)benzonitrile from commercial carbazole can form unique stacking structure to boost the reverse intersystem crossing and yellow room‐temperature phosphorescence emission. An efficient, persistent, nondiscoloring, and visible‐light excitable (300–520 nm) white‐emitting afterglow is first realized through the hybrid dual emission of both long‐lived thermally activated delayed blue fluorescence and isomer‐stabilized yellow phosphorescence at room temperature.