Molecular Engineering of Rylene Diimides via Sila-Annulation Toward High-Mobility Organic Semiconductors

The continuous innovation of captivating new organic semiconducting materials remains pivotal in the development of high-performance organic electronic devices. Herein, a molecular engineering by combining sila-annulation with the vertical extension of rylene diimides (RDIs) toward high-mobility organic semiconductors is presented. The unilateral and bilateral sila-annulated quaterrylene diimides (Si-QDI and 2Si-QDI) are designed and synthesized. In particular, the symmetrical bilateral 2Si-QDI exhibits a compact, 1D slipped π-π stacking arrangement through the synergistic combination of a sizable π-conjugated core and intercalating alkyl chains. Combining the appreciable elevated HOMO levels and reduced energy gaps, the single-crystalline organic field-effect transistors (SC-OFETs) based on 2Si-QDI demonstrate exceptional ambipolar transport characteristics with an impressive hole mobility of 3.0 cm² V^-1 s^-1 and an electron mobility of 0.03 cm² V^-1 s^-1, representing the best ampibolar SC-OFETs based on RDIs. Detailed theoretical calculations rationalize that the larger transfer integral along the π-π stacking direction is responsible for the achievement of the superior charge transport. This study showcases the remarkable potential of sila-annulation in optimizing carrier transport performances of polycyclic aromatic hydrocarbons (PAHs).