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

摘要

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.