| abstract |
A phosphorescent organic light emitting device having a homogeneous structure for the blocking layer and emissive layer combination. The homogeneous structure comprises substantially a single material for both the blocking layer and the host material for the emissive layer. Alternatively, the blocking layer and the host material for the emissive layer are selected from one or more of BAlq, SAlq and PAlq. The homogenous structure is disposed between an electron source and a hole source. The electron source comprises an electron transport layer, an electron injection layer and cathode. The hole source comprises a hole transport layer, a hole injection layer and an anode. The emissive layer is doped with a guest phosphor dopant. Additionally, a buffer layer containing LiF and Al, or layers of CuPc, Al and LiF are disposed between the cathode and the electron transport layer. |