Patent DE-102007020644-A1 (DE)
Title: Organic light emitting diode comprises electrode, counter electrode and light emitting organic area, which is arranged between the electrode and the counter electrode and has emission layer having a massive layer of fluorescent emitter
Inventor: SCHWARTZ GREGOR
IPC: H01L51/54
Filed: 2007-04-30
Abstract: The organic light emitting diode comprises an electrode, a counter electrode, a light emitting organic area, which is arranged between the electrode and the counter electrode and has an emission layer. The light emitting organic area emits light up to white light in several color area in the visible spectral area during applying an electric voltage on the electrode and the counter electrode. The emission layer consists of fluorescent emitter emitting light predominantly in the blue or blue green spectral area. The fluorescent emitter is connected to phosphorescent emitter. The organic light emitting diode comprises an electrode, a counter electrode, a light emitting organic area, which is arranged between the electrode and the counter electrode and has an emission layer. The light emitting organic area emits light up to white light in several color area in the visible spectral area during applying an electric voltage on the electrode and the counter electrode. The emission layer consists of fluorescent emitter emitting light predominantly in the blue or blue green spectral area. The fluorescent emitter is connected to phosphorescent emitter emitting light predominantly in non-blue spectral area. A triplet energy for energy level of a triplet state of fluorescent emitter in the emission layer is greater or approximately same than or as the triplet energy for energy level of a triplet state of the phosphorescent emitter. The organic light emitting area emits a portion of 5%, 10%, 15%, 20% or 25% of light in the visible spectral area as fluorescent light of singlet state of the fluorescent emitter in the emission layer. The emission layer consists of a massive layer of fluorescent emitter that is arranged to the phosphorescent emitter. The emission layer consists of an organic material in which a fluorescent emitter in the concentration of 0.1-50 mol.% and phosphorescent emitters are connected. The organic light emitting area has a further emission layer with phosphorescent emitter emitting light predominantly in non-blue spectral area. The emission layer transportably forms holes and the further emission layer transportably forms electrons, and the distance between a surface of the emission layer turned to the electrode or counter electrode formed as cathode (2) or anode (1) and a surface of the cathode or anode turned to the emission layer is smaller than the distance between the surface of the further emission layer turned to the cathode or anode and the surface of the cathode or anode turned to the further emission layer. A hole block layer (6) is arranged between the emission layer and the cathode and transports the electrons. The organic material of the hole block layer has highest occupied molecular orbital-level (HOMO level), which lies 0.3 eV higher than the HOMO-level of the fluorescent emitter in the emission layer. An electron block layer (7) is arranged between the emission layer and the anode and transports the holes. The organic material of the electron block layer has lowest unoccupied molecular orbital-level (LUMO level), which lies 0.3 eV higher than the LUMO-level of the fluorescent emitter in the emission layer. A minimum energy of singlet exiton and triplet exiton in the hole or electron block layer is greater than a minimum energy of singlet exiton and triplet exiton in the emission layer. The emission layer and/or further emission layer are formed multilayer. The emission layer has a thickness of 10-100 nm. The organic light emitting area emits white light. The phosphorescent emitters in the emission layer and/or further emission layer are emitters emitting light in the red, orange, yellow green spectral area. A doped organic layer is formed between the organic light emitting area and the electrode and/or the counter electrode. The doped organic layer is a p-doped layer with acceptor material or n-doped layer with donor material. The fluorescent emitter in the emission layer is a metal organic component or a complex component with a metal with atomic number of less than 40. The fluorescent emitter in the emission layer has an electron pulling substitute, an electron-pushing substitute, a functional group with electron acceptor property and a functional group with electron donor property.