Mirror-Symmetric Organic Two-Dimensional Crystals for Alternative Photon Transport Pathways.

Two-dimensional (2D) organic crystals have attracted significant attention due to their highly ordered structures and exceptional optoelectronic properties. However, the conventional forms are often limited to simple geometries, restricting functional diversity. Therefore, developing structural designs to overcome the limitation is of critical importance. Herein, we report a preparation route for mirror-symmetric V-shaped 2D organic crystals by utilizing differential attachment energies across crystal facets, combined with temperature, solution concentration, and viscosity to promote crystal growth, resulting in the synthesis of V-shaped crystals and the transition from 1D to 2D architectures. The two arms of the V-shaped crystal exhibit mirror symmetry, and half of the angle between the two arms is approximately 67°. According to the optical waveguide tests, 2D crystal exhibits an optical loss coefficient as low as 0.075 dB/µm. In the V-shaped 2D homostructure, photons propagate uniformly within each arm but exhibit an abrupt intensity change at the interface, revealing asymmetric waveguide behavior and altering photon transport pathways, forming an angle of about 134° with the original path. This work provides new insights into the precise fabrication and functional integration of unconventional organic crystals.