Nucleation Control-Triggering Cocrystal Polymorphism of Charge-Transfer Complexes Differing in Physical and Electronic Properties

Binary
charge-transfer complex polymorphs composed of perylene
and 4,8-bis­(dicyanomethylene)-4,8-dihydrobenzo-[1,2-b:4,5-b′]-dithiophene (DTTCNQ) were synthesized
separately via a simple artificial nucleation-tailoring method, in
both macroscopic and microscopic cocrystal engineering manners. The
two polymorphs were testified to be independently thermosalient in
the solid state, and the specific self-assembly derived from homogeneous
or heterogeneous nucleation by assistance of governable thermodynamic/kinetic
drive, leading to a change in the ordered p–n stacking structure.
The as-prepared polymorphic microcrystals afforded a significantly
varied (opto)­electronic property: high n-type transporting and good
photoresponsivity for β-complex, and ambipolar transporting
with ignorable photoresponsivity for α-complex, attributing
to the different charge-transfer and supramolecular alignment. This
work provides us a new route to the exploitation of donor–acceptor
complex family, making it possible to develop functional materials
and devices based on variable supramolecular binary structures.