Charge Generation Layer Segmentation for OLED Luminance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Charge generation efficiency in light emitting devices with charge generation layers interposed between organic layers is a limiting factor for luminance, as existing configurations do not effectively enhance electron and hole injection properties.
Innovation Solution
A light emitting device configuration that includes a charge generation layer with a first layer containing an electron transport material, a second layer with a metal and a hole injection material, and a third layer with a hole injection material, where the metal content in the third layer is less than in the second layer, improving electron injection properties and overall charge generation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a charge generation layer is introduced between organic layers to improve luminance, then charge generation efficiency is enhanced, but device complexity increases due to additional layers and materials
Solution Approach 1:
The charge generation layer is segmented into three distinct sub-layers (first, second, and third sub-layers) with different material compositions and functions. This segmentation allows each sub-layer to perform a specific function: the first sub-layer generates electrons, the second sub-layer generates holes, and the third sub-layer facilitates charge injection into the organic layer. By dividing the charge generation function into separate specialized layers, the patent achieves high charge generation efficiency while maintaining manageable device complexity through functional specialization.
Solution Approach 2:
The patent employs composite materials in the charge generation layer, combining organic electron transport materials with inorganic metal compounds (such as lithium fluoride, aluminum, or magnesium) in specific ratios. This composite approach leverages the advantages of both material types: organic materials provide good interface compatibility with the organic light-emitting layers, while inorganic metal compounds provide efficient charge generation. The composite structure enables effective charge generation without requiring overly complex device architectures.
2Productivity
If metal content in the charge generation layer is increased to improve charge generation efficiency, then luminance increases, but manufacturing cost increases due to expensive evaporation sources
Solution Approach 1:
The patent applies local quality by distributing metal content non-uniformly across the charge generation layer. The second sub-layer contains a higher metal content (5-50 at%) for efficient charge generation, while the first and third sub-layers contain lower metal content (0.1-10 at%). This localized concentration of metal in the critical charge generation region (second sub-layer) maintains high charge generation efficiency while reducing overall metal usage and manufacturing costs compared to uniform high metal content throughout the entire charge generation layer.
Solution Approach 2:
The patent optimizes the metal content parameter within specific ranges for each sub-layer to balance performance and cost. By defining precise metal content ranges (0.1-10 at% for first and third sub-layers, 5-50 at% for second sub-layer) and controlling the thickness of each sub-layer (1-50 nm), the patent achieves effective charge generation with reduced metal consumption. This parameter optimization allows the use of more cost-effective evaporation sources while maintaining high charge generation efficiency.
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 enhances the luminance of the light emitting device by increasing charge generation efficiency and light emission efficiency, while also reducing manufacturing costs by allowing the use of lower-cost evaporation sources for forming the metal-containing layers.
Implementation Method 1
a first layer containing an electron transport material
Implementation Method 2
a second layer containing a metal and a hole injection material
Implementation Method 3
each organic layer including a light emitting layer
Data Source
AI summary
Multiple organic layers (120) are located between a first electrode (110) and a second electrode (130), each organic layer including a light emitting layer. A charge generation layer (200) is located between mutually adjacent organic layers (120). In other words, the multiple organic layers (120) are mutually laminated and the charge generation layer (200) is located between the multiple organic layers (120). The charge generation layer (200) includes a first layer, a second layer, and a third layer. The first layer contains an electron transport material and the second layer contains a metal and a hole injection material. The third layer is formed using a hole transport material. The charge generation layer (200) contains an electron injection material for improving electron injection properties of the first layer, the charge generation layer provided on the first layer side than the second layer.