ortho-π-Extension of perylene diimides via one-pot annulation of imidazo[1,2-a]pyridine or imidazo[1,2-a]pyrazine for n-type organic field-effect transistors†

Abstract

Incorporation of nitrogen atoms into polycyclic aromatic hydrocarbon (PAH) imides has been proven to be a robust strategy to access organic materials with outstanding optoelectronic properties and extraordinary application prospects. In this work, two ortho π-extended perylene diimides (PDI), namely, PDI-IPD and PDI-IPZ have been synthesized by one-pot annulation of imidazo[1,2-a]pyridine and imidazo[1,2-a]pyrazine, respectively. The photophysical and electronic properties of these two compounds are investigated by UV-vis absorption, photoluminescence and cyclic voltammetry. Compared with the parent PDI, both PDI-IPD and PDI-IPZ exhibit pronounced bathochromic shifts of the absorption and emission maxima. The deep lying lowest unoccupied molecular orbital (LUMO) energy levels endow them electron-transporting (n-type) characteristics in organic field-effect transistors (OFETs) while PDI-IPZ showcases a superior electron mobility of 0.116 cm² V⁻¹ s⁻¹.