Hole-Transporting Carbazole-Based Imines

Abstract

Carbazole-based imines were synthesized by the reactions of 3-amino-9-ethylcarbazole with heteroaromatic aldehydes (3-formyl-9-ethylcarbazole or 3-formyl-10-(2-ethylhexyl)phenothiazine) or with 4,4′-bis(dimethylamino)benzophenone. The characterization of the derivatives synthesized by ¹H NMR and IR spectroscopy as well as by MS spectrometry is presented. The electron photoemission spectra of thin layers of the materials were recorded and the ionization potentials of ca 5.3 eV were established. Hole drift mobilities in the layers of bisphenol Z polycarbonate containing 50% of the electro-active material reached 4 × 10⁻⁶ cm²/Vs at an electric field of 1.4 × 10⁶ V/cm.

Keywords:

• Carbazole
• hole drift mobility
• imine
• ionization potential
• molecular glass

Acknowledgment

Financial support of this research by the Research Council of Lithuiania (grant No. TAP68/2010) is gratefully acknowledged. Dr. V. Gaidelis is thanked for the help in ionization potential measurements.

Notes

^a Concentration 10⁻⁵ mol l⁻¹. Excitation wavelength 295 nm.