Homogeneous Nucleation and Growth of Organic Semiconductors— [1]Benzothieno[3,2-b] Benzothiophene (BTBT) and Derivatives as Paradigmatic Herringbone Structures

A limited understanding of how π-conjugated molecules nucleate and grow into crystals remains a significant hurdle to the development of full structure–processing–property pipelines that are required for in-silico materials design. To gain insights into relationships among molecular structure, processing solvents, temperature, and crystallization behavior, we developed and deployed molecular dynamics (MD) simulation approaches to investigate the features of initial nucleation and growth events responsible for crystal development. Of particular interest are [1]benzothieno[3,2-b] benzothiophene (BTBT) and similar derivatives as these are paradigmatic herringbone-packed systems that display promising charge-carrier transport properties. In particular, we implement density restraints to induce supersaturation to prompt homogeneous crystallization in four solvent environments. This allows us to explore how concentration and solvent choice affect crystal nucleation and growth. We quantify atomistic-scale thermokinetic and physical properties of crystallization with the goal to provide atomic-scale information that can be used as insights for organic semiconductor design guidelines that include processing conditions