Film-forming hole transporting materials for high brightness flexible organic light-emitting diodes

Film-forming property of organic semiconductors is one of crucial factors for the performance of flexible organic light-emitting diode. In this work, two hole transporting materials based on triphenylamine were synthesized, which showed an outstanding film-forming property and could form free-standing films with a diameter of 4 mm. The spin-coated films on the flexible substrates showed an unobvious mechanical failure bended with radius of curvature no less than 6 mm. Photoelectron yield spectroscopy show that the two compounds embody suitable highest occupied molecular orbital levels (-5.14 eV and -5.25 eV) for hole injection. The sandwiched organic light-emitting diodes use poly[2-(4-3′,7′-dimethyloctyloxy)-phenyl]-p-phenylenevinylene) as emitting and electron transporting layer showed higher stability with increasing operation current density, an maximum luminance level of 103,690 cd m^-2. It demonstrate that the as-synthesized hole transporting materials hold a promising in high brightness flexible organic light-emitting diodes.