Organic EL Emitting Layer Structure for Higher Luminous Efficiency
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Solution Overview
Problem
Existing organic electroluminescence devices face challenges in enhancing performance, particularly in terms of luminous efficiency and overall device performance.
Innovation Solution
The device incorporates a dual emitting layer structure with specific host materials in each layer, where the first emitting layer contains a first compound represented by a specific formula and the second emitting layer contains a second compound represented by another specific formula, allowing direct contact between the layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a single emitting layer is used in the organic EL device, then the device structure is simple, but the luminous efficiency is limited due to the 25%:75% singlet:triplet exciton generation ratio
Solution Approach 1:
The emitting layer is divided into two distinct layers: a first emitting layer containing host material and emitting material, and a second emitting layer containing different host material and emitting material. This segmentation allows independent optimization of each layer for different exciton types, with the first layer handling singlet excitons and the second layer handling triplet excitons, thereby resolving the luminous efficiency limitation while maintaining manageable structural complexity
Solution Approach 2:
Different regions of the emitting structure are assigned different material compositions and properties. The first emitting layer uses host material with specific properties optimized for singlet exciton emission, while the second emitting layer uses host material with properties optimized for triplet exciton emission. This local quality differentiation enables each layer to maximize its contribution to overall luminous efficiency
2Loss of energy
If conventional host materials are used in the emitting layer, then the material selection is straightforward, but the overall device performance and luminous efficiency are enhanced only limitedly
Solution Approach 1:
The invention changes key parameters of the host materials, specifically selecting host materials with appropriate triplet energy levels (Et) relative to their respective emitting materials. The first host material has Et higher than the first emitting material, and the second host material has Et higher than the second emitting material. This parameter optimization enables efficient energy transfer and exciton management, significantly enhancing luminous efficiency while maintaining manufacturability through well-defined material selection criteria
Solution Approach 2:
The device employs composite material systems where host materials and emitting materials are carefully paired in each layer. The first layer combines host material (e.g., mCP, TCTA) with emitting material (e.g., OLED compounds), and the second layer combines different host material (e.g., TAPC, TPD) with different emitting material (e.g., Alq3, BCP). These composite material combinations are designed to achieve optimal energy level matching and exciton management, enhancing overall device 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 enhances the luminous efficiency and overall performance of the organic electroluminescence device.
Implementation Method 1
An organic electroluminescence device includes an anode, a cathode, a first emitting layer provided between the anode and the cathode, and a second emitting layer provided between the first emitting layer and the cathode
Data Source
AI summary
An organic electroluminescence device includes an anode, a cathode, a first emitting layer, and a second emitting layer provided between the first emitting layer and the cathode, in which the first emitting layer contains a first compound represented by a formula (101) below as a first host material, the second emitting layer contains a second compound represented by a formula (2) below as a second host material, and the first emitting layer is in direct contact with the second emitting layer.