Unsymmetrical phenanthro-imidazole/phenothiazine conjugates for optoelectronic applications

We designed and synthesized two small unsymmetrical phenanthro-imidazole/phenothiazine molecules with (OHM-2) and without (OHM-1) a phenyl-π-spacer. The optical and electrochemical properties were measured to determine the band-gap and HOMO energy values of these molecules. It was observed that the phenyl-π-spacer played a crucial-role in lowering the hole-reorganization energy, extending the conjugation for improved electrical properties, and tuning the optical/electrochemical properties for optoelectronic applications. An alkyl-chain introduced on structure increased the hydrophobicity, improving stability in ambient atmosphere applications. Unsymmetrical phenanthro-imidazole/phenothiazine molecules were shown to be a suitable, versatile hole-transporting material for high–performance optoelectronic devices.