Monoamine Hole Transport Layer for OLED Efficiency
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Solution Overview
Problem
Existing organic electroluminescent devices face challenges in achieving long life, high luminance, and high efficiency, particularly due to limitations in light emission efficiency, maximum light emission luminance, color purity, and durability issues related to electron transporting properties and electric reduction.
Innovation Solution
Incorporating specific organic compounds with pyridine, pyrazine, or triazine rings in the light-emitting layer and monoamine compounds in the hole transport layer, as defined by specific formulas, to enhance charge transport and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If tris(8-quinolinolato)aluminum is used in the light-emitting layer, then the device shows good luminance and luminous efficiency, but the light emission efficiency, maximum luminance, and color purity are insufficient
Solution Approach 1:
The patent changes the chemical parameters of the light-emitting layer by replacing conventional materials with specific pyridine, pyrazine, or triazine ring-containing compounds. This parameter change in molecular structure leads to improved light emission efficiency, maximum luminance, and color purity while maintaining good luminance characteristics.
Solution Approach 2:
The patent employs composite material strategy by combining the light-emitting layer containing pyridine/pyrazine/triazine compounds with a specifically designed hole transport layer containing compounds with electron-transporting capability. This composite structure resolves the contradiction by achieving synergistic effects between layers.
2Loss of energy
If phosphorescent emission is used to enhance light emission efficiency, then light emission efficiency should improve, but sufficient luminous efficiency is not yet obtained
Solution Approach 1:
The patent changes the emission mechanism parameter from conventional fluorescent or phosphorescent emission to a novel mechanism using pyridine/pyrazine/triazine ring compounds. This fundamental parameter change in the light-emitting layer's molecular structure enables achieving sufficient luminous efficiency that overcomes the limitations of traditional phosphorescent materials.
3Quantity of substance
If host materials with both hole transporting and electron transporting properties are used to concentrate recombination regions, then recombination concentration improves, but the device exhibits high tendency toward anode side recombination and fails to achieve high luminous efficiency
Solution Approach 1:
The patent applies segmentation by separating the hole transporting function and electron transporting function into different layers. The light-emitting layer contains electron-transporting compounds (pyridine/pyrazine/triazine compounds), while the hole transport layer contains dedicated hole transporting materials. This functional segmentation prevents excessive anode-side recombination and achieves high luminous efficiency.
Solution Approach 2:
The patent implements local quality by assigning specific functional properties to specific layers. The light-emitting layer is locally optimized for electron transport and light emission using pyridine/pyrazine/triazine compounds, while the hole transport layer is locally optimized for hole transport. This local functional differentiation resolves the recombination imbalance issue.
4Ease of operation
If conventional hole transporting materials like PPD or NPD are used, then hole transport function is provided, but high luminous efficiency, high luminance, or long driving life cannot be obtained
Solution Approach 1:
The patent uses composite materials strategy by combining conventional hole transporting materials (PPD or NPD) in the hole transport layer with novel pyridine/pyrazine/triazine ring compounds in the light-emitting layer. This composite approach maintains effective hole transport while significantly improving driving life and luminous efficiency through the synergistic interaction between layers.
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
The proposed solution results in an organic electroluminescent device with improved long life, high luminance, and high efficiency, along with excellent electrical durability, making it suitable for various applications beyond display use.
Implementation Method 1
the present invention relates to an organic electroluminescent device
Data Source
AI summary
The present invention provides an organic electroluminescent device exhibiting a long life, a high luminance, and a high efficiency.An organic electroluminescent device comprising on a substrate an anode, a hole transport layer, an organic light-emitting layer, and a cathode, wherein the organic light-emitting layer contains an organic compound having a pyridine ring, a pyrazine ring, or a triazine ring as a partial structure and the hole transport layer contains a monoamine compound represented by the following formula (I):wherein R1 to R9 represent a hydrogen atom, an aryl group, or an alkyl group; R1 to R9 may be the same or different from each other; and R1 to R9 may further have an aryl group or an alkyl group as a substituent in the case where R1 to R9 are an aryl group or an alkyl group.