New fluorescent columnar mesogens derived from phenanthrene–cyanopyridone hybrids for OLED applications

Abstract

We report the design, synthesis, and self-assembly of a novel series of pseudodiscoid dyads comprising electron-rich dialkoxyphenanthrene and trialkoxyphenyl rings appended to an electron-deficient cyanopyridone core. Evidently, all the members of the series exhibited bi-mesophases with prospective columnar mesomorphism; moreover, it was steady under ambient conditions. The electro-optical studies revealed that the new liquid crystalline materials were efficient green light emitters both in solution and LC states with substantial chromaticity. Further, their theoretical studies (DFT) revealed that the molecules possess good intramolecular charge transport behavior. These superior properties of the LC materials render them to become promising candidates for OLED applications. Their electroluminescence competence was studied by fabricating doped and non-doped simple-architecture OLED devices. One of the doped devices with Py-2 as the emissive layer exhibits the highest deep-green electroluminescence with a brightness of 1898 cd m⁻² at 4.23 V having CIE coordinates of (0.312, 0.606).