Triarylamine-combined nitronyl nitroxide and its hole-transporting property

N,N-Bis(4-methoxyphenyl)-4-(1-oxyl-3-oxide-4,4,5,5-tetramethylimidazolin-2-yl)phenylamine (1) was synthesized as a durable nitronyl nitroxide radical combined with a triarylamine moiety. Cyclic voltammetry and UV–Vis absorption spectra during the electrochemical oxidation of 1 revealed that the first redox was derived from the triarylamine moiety. The ionization potential of 1 was measured by photoelectron spectroscopy to be −5.4 eV, which was appropriate as a hole-transporting material. A single-layer hole-only device was fabricated with the radical molecule 1 dispersed in polycarbonate (ITO/1:polycarbonate/Al): The radical-layer exhibited a maximum current density of 0.2 mA/cm2, which was applicable for organic electronic devices.

Graphical abstractA durable nitronyl nitroxide molecule combined with the triarylamine moiety was prepared as a new hole-transporting molecule. Electrochemical measurements and photoelectron spectroscopy of the radical molecule showed a reversible redox with the ionization potential of −5.4 eV. The hole-transporting property was proved by current density–electric field plots for the single-layer device.Figure optionsDownload full-size imageDownload as PowerPoint slide