Synthesis and opto-electrochemical properties of tribenzo[a,c,i]phenazine derivatives for hole transport materials

Abstract

In this work, five novel 3,6-disubstituted-tribenzo[a,c,i]phenazine (2–6) derivatives were synthesized in good yield by employing a palladium catalyzed C–N bond forming amination reaction and fully characterized. Photophysical properties of 2–6 were studied both in solvent and neat solid film by UV-vis absorption, fluorescence spectroscopy and electrochemical properties by cyclic voltammetry. Absorption spectra of 2–6 showed intramolecular charge transfer (ICT) transitions in the range of 460–512 nm in solution. The HOMO and LUMO energy levels of 2–6 are in the range of −5.18 to −5.35 eV and −3.06 to −3.17 eV respectively with electrochemical bandgap within the range of 2.12–2.29 eV. HOMO energy levels of 2–6 are comparable with most commonly used hole transporting materials such as TPD, α-NPD and spiro-OMe-TAD etc. and thus make them potential candidates for the hole transporting material in organic electronics.