Blue Light Emitting Diodes based on a partially conjugated Si-containing PPV-copolymer in a multilayer configuration

Efficient blue Light Emitting Diodes (LEDs) based on a novel partially conjugated co-polymer (SiPPV) have been realized by a combination of techniques known to enhance the quantum efficiency of organic devices. The copolymer is homogeneously blended in a PVK-matrix to reduce the number of non-radiative decay paths. In single-layer devices the high barrier at the Al top electrode limits efficient electron-injection into the device. In double-layer structures with an evaporated PBD-film at the cathodic side, electron and hole currents are much more balanced, resulting in an internal quantum efficiency of 3.2%. The average turn-on field of a double-layer device is reduced compared to a single-layer LED.