An enhanced operational stability of organic light emitting devices with polymeric buffer layer

A uniform and robust polymer-based hole injection layer (HIL) was formed by spin-casting process in an ambient air condition. The rough surface of indium tin oxide (ITO) was covered by this polymer-based HIL which plays an important role as a buffer layer. The utilization of this buffered HIL polymer resulted in an enhanced long-term stability of organic light emitting devices (OLEDs). In addition, we found that the precise control of hole current flow is possible by doping of 9,10-dicyanoanthracene (DCA) with moderate electron affinity (~3.5 eV) plausibly due to a strong dipole interaction with the polymeric HIL material. As a result, a new buffer layer doped with DCA showed a substantially controlled hole injection into an emitting layer (EML) which causes a much more enhanced lifetime of the blue OLED by a factor of 4.3.