Self-Assembly of a Highly Emissive Pure Organic Imine-Based Stack for Electroluminescence and Cell Imaging

We
demonstrated that a purely organic stack, namely, TPE-3-stack,
can be assembled in high yield by using dynamic imine chemistry. TPE-3-stack
emits strong fluorescence not only in the solid state (ϕPL = 83%) but also in dilute solutions (e.g., ϕPL = 82% in DMSO), which is significantly distinct from the case of
the aggregation-caused quenching (ACQ) and aggregation-induced emission
(AIE) chromophores. In addition, it shows high spectral, thermal,
and chemical stabilities as well as excellent solubility in common
solvents. Therefore, this stack is feasible for fabricating a solution-processed
electroluminescent device, which displays brightness over 1000 cd
m–2 and a current efficiency up to 2.3 cd A–1. TPE-3-stack is also demonstrated as a promising
fluorescent visualizer for lysosome imaging. Such characteristics
of the stack compound were attributed to the efficient suppression
of intramolecular rotation and vibration by locking its structure
into the rigid framework by means of a self-assembly strategy.