Organic Light-Emitting Element With Expanded Recombination Region
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Solution Overview
Problem
Existing organic light-emitting devices with stacked light-emitting layers face challenges in achieving a longer driving lifetime and higher luminance, particularly when using phosphorescent materials that rely on triplet excitons.
Innovation Solution
The organic light-emitting device is configured with a stack of at least two light-emitting layers, where the first light-emitting layer contains a first organic compound, a second organic compound, and a first light-emitting material, and the second light-emitting layer contains the first organic compound, a third organic compound, and a second light-emitting material. This configuration satisfies specific energy level relationships to form electron injection barriers and expand the recombination region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If stacked light-emitting layers are used to improve durability, then the driving lifetime is extended, but the device complexity increases
Solution Approach 1:
The light-emitting layer is divided into multiple stacked layers (first light-emitting layer and second light-emitting layer), each containing different organic compounds and light-emitting materials. This segmentation allows the device to achieve extended driving lifetime through distributed recombination regions while maintaining manageable structural complexity through systematic layer design
Solution Approach 2:
Different regions of the stacked light-emitting layers are designed with specific local properties: the first light-emitting layer contains a first organic compound, second organic compound, and first light-emitting material, while the second light-emitting layer contains the first organic compound, third organic compound, and second light-emitting material. This local quality differentiation optimizes recombination region distribution and material stability in specific areas to extend driving lifetime
2Use of energy by moving object
If phosphorescent materials utilizing triplet excited state are used to improve light-emitting efficiency, then the efficiency increases, but the material deteriorates due to transition to higher excited state
Solution Approach 1:
The energy level parameters of the organic compounds and light-emitting materials are carefully selected and optimized. The system satisfies specific energy level relationships where the triplet excited state energy is controlled to prevent transition to higher excited states, thereby maintaining high light-emitting efficiency while preventing material deterioration and improving durability
Solution Approach 2:
The light-emitting layers use composite material systems combining multiple organic compounds (first organic compound, second organic compound, third organic compound) with light-emitting materials. This composite approach allows the system to utilize triplet excited states for efficient light emission while the combined material structure prevents deterioration through controlled energy level relationships
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 durability performance of the light-emitting layers, leading to a longer driving lifetime and higher luminance for the organic light-emitting device, while also reducing the likelihood of color shifts due to differential degradation of green and red light emissions.
Implementation Method 1
an electron injection barrier is formed between the light-emitting layers, and a recombination region of holes and electrons thereby expands
Implementation Method 2
The injection of electrons and holes from this pair of electrodes generates excitons of a light-emitting organic compound in the organic compound layer, and the organic light-emitting device emits light when the excitons return to the ground state
Implementation Method 3
devices using efficiency-improving materials, such as phosphorescent materials and delayed fluorescent materials... since any of the materials has a light-emitting mechanism through the triplet excited state
Implementation Method 4
phosphorescent materials... have a light-emitting mechanism through the triplet excited state
Data Source
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AI summary
The present disclosure provides an organic light-emitting device which includes a light-emitting layer stack including at least two stacked light-emitting layers and in which an electron injection barrier is formed by adjusting HOMOs and LUMOs of organic compounds constituting the two light-emitting layers to expand an exciton combination region. A first light-emitting layer contains a first organic compound, a second organic compound, and a first light-emitting material, a second light-emitting layer contains the first organic compound, a third organic compound, and a second light-emitting material, and the organic light-emitting device satisfies formulas [1] and [2] below. S1L1−S1L2<S1L1−S1O1 LUMOO2>LUMOO3 S1L1: S1 level energy of the first light-emitting material S1L2: S1 level energy of the second light-emitting material S1O1: S1 level energy of the first organic compound LUMOO2: energy level of lowest unoccupied molecular orbital of the second organic compound LUMOO3: energy level of lowest unoccupied molecular orbital of the third organic compound