Organic Light-Emitting Device Layer Segmentation for Lifetime
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current current excitation type light-emitting elements using organic compounds have short lifetimes, limiting their practical application in long-term use due to rapid degradation of the light-emitting region, especially when adjacent to hole-transporting or electron-transporting layers.
Innovation Solution
The light-emitting region is positioned at the center of the light-emitting layer, comprising layers with different carrier transport properties, where the first layer includes a hole-transporting organic compound and the second layer includes an electron-transporting organic compound, both formed from the same organic compound, with specific molecular orbital levels and reversible to oxidative and reductive reactions, to enhance stability and longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the light-emitting region is positioned adjacent to hole-transporting or electron-transporting layers, then carrier injection and recombination are enhanced, but the lifetime of the light-emitting element decreases due to rapid degradation
Solution Approach 1:
The light-emitting layer is divided into two distinct layers: a first light-emitting layer adjacent to the hole-transporting layer and a second light-emitting layer adjacent to the electron-transporting layer. This segmentation allows each layer to be optimized for its specific interface, reducing degradation at both interfaces while maintaining high carrier injection efficiency.
Solution Approach 2:
Different regions of the light-emitting structure are assigned different functional qualities. The first light-emitting layer is positioned to optimize hole injection and recombination, while the second light-emitting layer optimizes electron injection and recombination. This local optimization reduces stress and degradation at each interface, extending overall device lifetime.
2Device complexity
If a single light-emitting layer is used, then the device structure is simple, but the lifetime is short due to degradation at interfaces with transport layers
Solution Approach 1:
The light-emitting layer is segmented into two sub-layers with different organic compounds, each optimized for its adjacent interface. This segmentation resolves the contradiction by accepting increased structural complexity as a necessary trade-off to achieve significantly improved lifetime and reliability.
3Manufacturing precision
If the same organic compound is used in both light-emitting layers, then manufacturing precision is maintained, but the light-emitting regions may not be optimally positioned
Solution Approach 1:
Different organic compounds are selected for the first and second light-emitting layers based on their specific interface requirements. The first layer uses a compound optimized for hole-transporting layer interface compatibility, while the second layer uses a compound optimized for electron-transporting layer interface compatibility, achieving optimal positioning and performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration significantly reduces degradation and extends the lifetime of the light-emitting element by maintaining a stable light-emitting region, leading to improved reliability and longer operational life in electronic devices.
Implementation Method 1
the organic compound having a hole-transporting property and the compound having an electron-transporting property are reversible to an oxidative reaction and a reductive reaction
Implementation Method 2
the organic compound having a hole-transporting property and the compound having an electron-transporting property are reversible to an oxidative reaction and a reductive reaction
Implementation Method 3
electrons and holes are injected into a layer including a light-emitting organic compound from a pair of electrodes by voltage application to a light-emitting element, so that a current flows therethrough. The electrons and holes (i.e., carriers) are recombined, and thus, the light-emitting organic compound is excited. The light-emitting organic compound returns to a ground state from the excited state, thereby emitting light.
Data Source
AI summary
The present invention provides a light-emitting element inducing an electron-transporting layer and a hole-transporting layer between a first electrode and a second electrode; and a first layer and a second layer between the electron-transporting layer and the hole-transporting layer, wherein the first layer includes a first organic compound and an organic compound having a hole-transporting property, the second layer includes a second organic compound and an organic compound having an electron-transporting property, the first layer is formed in contact with the first electrode side of the second layer, the first organic compound and the second organic compound are the same compound, and a voltage is applied to the first electrode and the second electrode, so that both of the first organic compound and the second organic compound emit light.