Selective doping of multilayer organic light emitting devices

Doping of organic light emitting diodes (OLEDs) has well-established benefi ts such as tuning emission wavelengths, as well as enhancing device lifetim e and quantum efficiency. The use of low percentage doping within the emiss ive layer is an established tool for the study of energy transfer processes in OLEDs, allowing one to trace electron and hole movement and exciton for mation. Delta doping, in which a thin layer of the dopant material alone is incorporated in the device, has the added advantage of a thinner sensing l ayer and an electroluminescence spectrum distinct from that of the host mat erial. In an ongoing effort to further our understanding of electroluminesc ent emission processes, we have fabricated multilayer OLEDs which incorpora te a narrow (<1 nm) delta-doped DCM region within the emissive layer. The d evices studied were deposited on indium tin oxide (ITO) on glass substrates using thermal evaporation, with a structure of ITO, TPD (40 nm)/selectivel y doped Alq(3) (40 nm)/Al (100 nm). The relationship between the doping pro file and the emission characteristics will be discussed. (C) 2000 American Vacuum Society. [S0734-2101(00)02002-9].