Spontaneous and reverse-bias induced recovery behavior in organic electroluminescent diodes

Double-layer organic electroluminescent diodes composed of a spin-coated polyvinylcarvbazole layer and a vacuum-sublimed tris-(8-hydroxyquinoline)aluminum layer were prepared. The diodes were driven at constant voltage and were also kept under short-circuit or reverse-bias conditions. Observations of luminance-current density-voltage relations at constant voltage driving were repeated, The decrease of both luminance and current density during constant voltage driving was observed. Both spontaneous and reverse-bias assisted recoveries of device performances were observed, and these degradation and recovery phenomena were discussed in terms of the movement of ionic impurities in organic layers. (C) 1998 American Institute of Physics. [S0003-6951(98)03819-4].