Contact formation at the C60/alkali-metal fluoride/Al interface

Efficient contact formation is critical in organic electroluminescence and photovoltaic devices that utilize fullerene (C-60). Unlike traditional electron transport molecules, such as tris-(8-hydroxy-quinolinato)aluminum (Alq(3)), C-60 is found to be highly selective of injection layers. Charge injection properties of alkali-metal fluoride injection layers at the C-60/Al cathode interface of organic light emitting diodes were studied. LiF is found to be unique amongst the alkali-metal fluorides in producing an Ohmic contact. The device performance is strongly linked to the size of the vapor phase fluoride molecules. The observed phenomena are explained by an intercalation region at the metal/organic interface. (c) 2008 American Institute of Physics.