Characteristics of organic electroluminescent devices with vapor deposition polymerized hole transport layers

Organic electroluminescent devices were successfully fabricated using a thin polymeric film dispersing a hole transport material into an aromatic polyimide and the molecular film of an organometallic chelate complex. To obtain high efficiency and stability, we attempted to prepare a hole transport layer (HTL) through vapor deposition polymerization, a fully dry process without use of solvent. X-ray photoemission spectroscopy and atomic force microscopy were performed for the structural investigation of the HTL. The charge injection of the device with the polyimide HTL was initialized at an applied voltage of 5.8 V. The luminance and luminous efficiency at 11 V were ca. 4,200 cd/m(2) and 16.5 lm/W, respectively.