Rational Control of Packing Arrangements in Organic Semiconducting Materials toward High-Performance Optoelectronics

Organic semiconducting materials have sparked a great deal of interest because of their structural versatility, lightweight, mechanical flexibility, as well as low temperature and large area fabrication, opening up possibilities for the development of next-generation electronic devices. Packing arrangements of organic semiconducting materials influence significantly the optoelectronic performance by alteration of electronic couplings, band structures, and exciton behaviors. The packing structures of small-molecule organic semiconductors can be typically classified into herringbone, slipped, and brickwork motifs. The preferred packing arrangement depends on the steric hindrance driven by the molecular structure and the weight of contribution of each interaction term, which are closely associated with the unpredictable and uncontrollable process of crystal nucleation and growth, involving lots of multiple variables such as the weak and subtle intramolecular or intermolecular interactions in organic materials. Therefore, it remains a long-standing challenge to tailor precisely the packing arrangements for high-performance or multifunctional organic semiconducting materials. In addition, the in-depth relationship between packing arrangements and optoelectronic properties is far from clear, preventing the development of high-performance organic optoelectronic materials.