PHOTOLUMINESCENCE QUENCHING OF ALQ(3) BY METAL-DEPOSITION - A SURFACEANALYTICAL INVESTIGATION

The importance of the interfacial properties in organic light-emitting devices (OLED) is well recognized. We will describe our recent effort s to understand interfaces in OLEDs using surface/interface analytical techniques in a well controlled ultrahigh vacuum environment. We obse rved severe photoluminescence quenching of organic thin films comprisi ng of a model OLED material, namely tris-(8-hydroxyquinoline) aluminum (Alq(3)), upon deposition of a number of metals. Such quenching may s everely affect the electroluminescence device efficiency. We have inve stigated the interfaces using x-ray photoemission spectroscopy and ult raviolet photoemission spectroscopy, and studied the intriguing proces s of the interface formation at an atomic/molecular level. We will sho w that microscopic surface and interface properties are intimately rel ated to the device characteristics and performance. (C) 1998 American Vacuum Society.