Organic EL Element Intermediate Layer Dopant Distribution

The patent applies local quality by creating distinct regions with different material properties within the light-emitting layers. The intermediate layer has high electron transportability to efficiently transport electrons, while the blue and green light-emitting layers have balanced electron and hole transportability to achieve uniform carrier recombination distribution. This spatial variation in material properties resolves the contradiction by localizing high electron transportability only where needed (intermediate layer) while maintaining reliability in other regions.

The patent changes the transportability parameters of different layers to resolve the contradiction. Specifically, it adjusts the electron and hole transportability ratios (μe/μh) of the blue and green light-emitting layers to be within 0.01 to 100, which prevents excessive concentration of recombination regions. Simultaneously, the intermediate layer maintains high electron transportability for efficient electron transport. This parameter optimization resolves the contradiction between speed and reliability.

The patent applies local quality by assigning different material compositions and transportability characteristics to each light-emitting layer (red, green, blue) and the intermediate layer. Each layer is optimized with specific electron and hole transportability ratios to ensure uniform carrier recombination and balanced light emission from all colors. This localized optimization of material properties enables all RGB layers to contribute equally to white light emission, resolving the contradiction between versatility and balanced performance.

The patent uses composite materials strategy by combining multiple light-emitting layers with different color emissions (red, green, blue) and an intermediate layer with specific transport properties. This composite structure allows each layer to contribute its specific color while the intermediate layer ensures balanced carrier distribution, achieving both white light emission capability and balanced light output from all layers.

The patent applies local quality by creating a spatial distribution of recombination regions throughout the blue and green light-emitting layers rather than concentrating them at the interface. This is achieved by optimizing the electron and hole transportability ratios of these layers to be within 0.01 to 100, which ensures uniform carrier injection and recombination distribution. The intermediate layer maintains high electron transportability for efficient electron transport, while the light-emitting layers have balanced transport properties to distribute recombination uniformly, thus improving both productivity and durability.

The patent applies beforehand cushioning by designing the blue and green light-emitting layers with balanced electron and hole transportability before the degradation problem occurs. This preventive design ensures that carrier recombination is uniformly distributed from the beginning of device operation, preventing the concentration of stress and degradation at specific interfaces. The optimized transportability ratios act as a cushion against premature degradation, extending the device lifetime while maintaining efficient electron transport.