Organic EL Device with Segmented Emitter Layers
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Solution Overview
Problem
Current organic electroluminescence devices face challenges in achieving high luminous efficiency due to limitations in the design and materials used in their emitting layers and electron blocking layers.
Innovation Solution
The proposed solution involves an organic electroluminescence device configuration with a specific arrangement of emitting layers and an electron blocking layer, where the first emitting layer includes a host material represented by a particular compound formula, the second emitting layer includes another host material, and the electron blocking layer has a compound with an ionization potential exceeding 5.67 eV, ensuring direct contact between these layers to enhance light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional emitting layer structures are used, then device simplicity is maintained, but luminous efficiency is insufficient
Solution Approach 1:
The emitting layer is divided into multiple distinct emitting layers (first emitting layer, second emitting layer, etc.), each with specific host materials and triplet energy characteristics. This segmentation allows optimization of exciton management and light emission in each layer, resolving the contradiction by achieving high luminous efficiency through structured complexity rather than simple uniform design.
Solution Approach 2:
Each emitting layer is assigned specific local properties: the first emitting layer has a host material with triplet energy ≥ 2.7 eV, the second emitting layer has a host material with triplet energy ≥ 2.1 eV. This local quality differentiation optimizes exciton confinement and emission characteristics in specific regions, achieving high luminous efficiency without requiring complex device-level modifications.
2Use of energy by moving object
If electron blocking layer with insufficient ionization potential is used, then ease of manufacture is maintained, but electron leakage occurs reducing efficiency
Solution Approach 1:
The electron blocking layer material is selected based on a specific parameter threshold: ionization potential ≥ 5.67 eV. This parameter change criterion ensures effective electron blocking while maintaining ease of manufacture by providing a clear material selection guideline. The high ionization potential prevents electron leakage, improving electron injection efficiency into the emitting layers.
3Use of energy by moving object
If triplet excitons are not properly managed, then device simplicity is maintained, but energy loss increases reducing luminous efficiency
Solution Approach 1:
The emitting layers are designed with specific triplet energy levels before exciton formation occurs. The first emitting layer's host material has triplet energy ≥ 2.7 eV and the second has ≥ 2.1 eV, creating a energy gradient that preliminarily directs triplet exciton migration and utilization. This preliminary energy level design ensures efficient triplet exciton management without requiring complex additional structures.
Solution Approach 2:
The patent converts the potentially harmful effect of triplet exciton accumulation (which causes energy loss) into a beneficial mechanism by designing emitting layers with specific triplet energy levels. The triplet energy gradient between layers promotes beneficial triplet exciton migration and utilization, transforming what would be energy waste into enhanced luminous 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 significantly improves the luminous efficiency of the organic electroluminescence device by optimizing the interaction between the emitting layers and the electron blocking layer, leading to enhanced light emission performance.
Implementation Method 1
an electron blocking layer disposed between the first emitting layer and the anode, in which: the first emitting layer and the electron blocking layer are in direct contact with each other; the electron blocking layer includes a third compound; and an ionization potential Ip(HT) of the third compound satisfies a numerical formula (M1) below, Ip(HT) ≥5.67 eV (M1)
Implementation Method 2
When a voltage is applied to an organic EL device, holes are injected from an anode and electrons are injected from a cathode into an emitting layer. The injected electrons and holes are recombined in the emitting layer to form excitons.
Data Source
AI summary
An organic electroluminescence device includes: a first emitting layer disposed between an anode and a cathode; a second emitting layer disposed between the first emitting layer and the cathode; and an electron blocking layer disposed between the first emitting layer and the anode, in which the first emitting layer and the second emitting layer are in direct contact with each other; the first emitting layer and the electron blocking layer are in direct contact with each other; the first emitting layer includes a first compound represented by a formula (1) below; the first compound includes at least one group represented by a formula (11) below; the second emitting layer includes a second compound represented by a formula (2); the electron blocking layer includes a third compound; and the third compound satisfies a formula (M1) below.