Solvent-molecule interactions govern crystal habit selection in naphthalene tetracarboxylic diimides

Controlling hierarchical structural development in organic semiconductors, and across synthetic materials more broadly, is critical to the performance of the material in device applications. Such regulation across multiple scales – from the atomic level to the macroscale – however, is a challenging task given the often-heterogeneous nature of interactions in the processing environment that determines the kinetics and thermodynamics of materials growth. Here, we elucidate factors that govern the crystal habit of a core-chlorinated naphthalene diimide (NTCDI-1), and demonstrate the ability to tune its shape in thin films during post-deposition solvent-vapor annealing. Judicious selection of solvent choice and solvent-vapor concentration con-trols the growth kinetics along different crystallographic axes, and thus the resulting habit; we can access isotropic plates that span hundreds of microns to highly anisotropic needles whose long axis can be many millimeters of crystals adopting the same packing polymor...