Deposition of TPD polymer by ionization-assisted method and its application to organic EL device

Triphenyldiamine (TPD) compounds, which are efficient hole transport materials for the organic electroluminescence devices, suffer from insufficient thermal instability. This paper describes ionization-assisted deposition of an acrylated TPD monomer (TPD-ac). The ionization-assisted method can generate chemically excited species that leads to polymerization of the material. As a consequence, thermal stability was remarkably improved by the ionization-assisted deposition. The polymer yield was about 46% without heating the substrate, and 77% at the substrate temperature of 60degC. The polymerization was also enhanced by post-annealing of the film. The polymerized film was shown to work as the hole transport layer for the organic EL device. (author)