Highly Luminescent Blue Emitter with Balanced Hybridized Locally and Charge-Transfer Excited-States Emission

In this work, we perform an in-depth investigation of the optoelectronic properties of a blue emitter (4''-(diphenylamino)-2''-methyl-[1,1':4',1''-terphenyl]-4-carbonitrile), which was reported earlier. Lippert-Mataga analysis of the emission spectra obtained in solvents of varying polarity reveal charge transfer (CT) contributions to the first singlet excited state, S-1. Multi-reference quantum chemical calculations clearly show a balanced local excitation (LE) and CT character of the S-1 state and suggests the presence of a LE triplet state, T-2, in its energetic vicinity. Finally, organic light emitting diodes (OLED) revealed blue emission at 451 nm and an external quantum efficiency (EQE) of 2 %, corresponding to an internal quantum efficiency (IQE) of circa 10 %.

Automated summary

In this study, we investigated the optoelectronic properties of a previously reported blue emitter. The analysis of the emission spectra in solvents with different polarities indicated charge transfer contributions to the first singlet excited state, S-1. Quantum chemical calculations revealed a balanced local excitation and charge transfer character of the S-1 state, and suggested the presence of a local excitation triplet state, T-2, in its energy vicinity. Finally, organic light emitting diodes exhibited blue emission at 451 nm with an external quantum efficiency of 2% and an internal quantum efficiency of approximately 10%.