US Patent 7923925 Light emitting device with a stopper layer structure

Electroluminescent (EL) devices structures are provided comprising a hot electron stopper layer structure to capture hot electrons and dissipate their energy, thereby reducing damage to the transparent conducting oxide (TCO) layer and reducing other hot electron effects, such as charging effects, which impact reliability of EL device structures. The stopper layer structure may comprise a single layer or multiple layers provided between the TCO electrode layer and the emitter structure, and may also function to reduce diffusion or chemical interactions between the TCO and the emitter layer structure. Optionally, stopper layers may also be provided within the emitter structure. Suitable stopper layer materials are wideband gap semiconductors or dielectrics, preferably transparent at wavelengths emitted by the EL device characterized by high impact ionization rates, and/or high relative permittivity relative to adjacent layers of the emitter structure.