Degradation of organic light-emitting devices due to formation and growth of dark spots

We present our in-situ experimental observations of dark spot growth in OLE D devices using optical microscopy. In order to IN understand the formation mechanism of dark spots, we employed silica particle to intentionally crea te some predictable pinhole defects on the protective layer. We found a lin ear growth of all dark spot as well as a linear correlation between growth rate and area. These results indicate that dark spot formation is related t o corrosion of the calcium or other materials with water and oxygen through pinhole defects. Furthermore, we found a correlation between the degradati on of entire devices and growth of all dark spots, which allows us to predi ct the lifetime of entire devices. (C) 2001 Elsevier Science B.V. All right s reserved.