A General Synthetic Strategy to a Library of Luminescent All-Organic Core–Shell Microstructures

Achieving
good control over all-organic core–shell configurations
represents an enormous challenge due to the difficulties in pairing
appropriate constituent materials and tuning their growth kinetics.
Here, we first prepare a series of structure- and color-tunable organic
binary charge-transfer (CT) microtubes, and then use a seed-mediated
strategy to encapsulate a pre-existing CT crystal with another one
into dual-emitting core–shell heterostructures. Specific intermolecular
interactions and similar molecular packing motifs among diverse CT
crystals enable tunable two-photon excited fluorescence (TPEF), comparable
lattice distances and small structural mismatch, which can be used
to direct the rational construction of such a configuration with integrated
TPEF properties. By tracking the real-time growth processes, we infer
that the core–shell configuration made of all-organic CT crystals
was determined depending on surface-interface energy balance and desired
lattice matching. Upon incorporation of a dopant into a shell, its
emission color can thus be tailored, giving more color-tunable core–shell
configurations. The present two-step epitaxial strategy provides a
simple yet effective approach to access a library of core–shell
heterostructures, which opens a door to construct functional organic
heterostructures for optoelectronic devices.