Manipulating Molecular Configurations of Organic Charge-Transfer Cocrystals with Programmable Near-Infrared Emission for Dual-Emission Optical Waveguide.

Molecular engineering in molecular configuration was successfully applied to finely design the advanced organic semiconductors. However, it has rarely been investigated in organic charge-transfer (CT) cocrystals with desired optoelectronic properties that could be controllably prepared via a facile self-assembly process. Herein, the organic benzo[c]phenanthrene (BcP)-based CT cocrystals with a programmable near-infrared (NIR) emission peak beyond 760 nm were rationally designed via manipulating the BcP molecular skew angle for an anisotropic packing mode. Notably, the torsional distortion of BcP molecule induced by CT interaction leads to a reduced dihedral angle from 11.95° to 10.78° for a minimized steric hindrance, showing a NIR emission red-shifted to 875 nm. Furthermore, these NIR cocrystals with high chemical/structural compatibility were purposefully integrated into the organic axial-branch heterostructure by adjusting CT interaction intensity in the horizontally epitaxial-growth process, which demonstrates a tunable spatial exciton conversion and dual-emission optical waveguide for optical logic gate. This confinement-assisted CT modulation strategy presents a versatile route to high-performance NIR emitters and hierarchical heterostructures for integrated optoelectronics applications.