Organic EL Emitting Layer Layout for Higher Luminous Efficiency
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Solution Overview
Problem
Existing organic electroluminescence devices with multiple emitting layers require further improvements in performance, particularly in luminous efficiency.
Innovation Solution
The device incorporates a first and second emitting layer with distinct host materials, where the triplet energy of the first host material is greater than that of the second, and the diffusion coefficient of the first host material exceeds 3.0×10−9 cm²/s, enhancing the triplet-triplet fusion process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple emitting layers are layered to enhance performance, then luminance and emission wavelength are improved, but luminous efficiency deteriorates
Solution Approach 1:
The patent changes the triplet energy parameter relationship between host materials in different emitting layers. Specifically, the first host material has higher triplet energy than the second host material, creating an energy gradient that enables efficient triplet exciton transfer from the first emitting layer to the second emitting layer, thereby improving luminous efficiency while maintaining multi-layer performance
Solution Approach 2:
The patent assigns different host materials with specific triplet energy characteristics to different emitting layers. The first emitting layer uses a host material with higher triplet energy, while the second emitting layer uses a host material with lower triplet energy, creating localized energy differences that drive efficient exciton transfer and improve overall device efficiency
2Ease of manufacture
If multiple emitting layers are layered to enhance performance, then emission wavelength is improved, but luminous efficiency deteriorates
Solution Approach 1:
The patent utilizes changes in triplet energy parameters across different host materials to enable controlled exciton transfer. By selecting host materials with specific triplet energy relationships (first host > second host), the patent achieves both wavelength control through multiple layers and improved luminous efficiency via efficient energy transfer
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 improves the luminous efficiency and overall performance of the organic electroluminescence device by optimizing the triplet energy and diffusion properties of the host materials.
Implementation Method 1
a diffusion coefficient D1 of the triplet energy of the first host material T1(H1) calculated according to a diffusion equation is 3.0×10−9 (cm2/s) or more
Implementation Method 2
When 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 holes and electrons are recombined in the emitting layer to form excitons.
Data Source
AI summary
An organic EL device includes an anode, a cathode, and an emitting layer disposed between the anode and the cathode, in which the emitting layer includes a first emitting layer and a second emitting layer, the first emitting layer contains a first host material and a first luminescent compound, the second emitting layer contains a second host material and a second luminescent compound, the first host material and the second host material are mutually different, the first luminescent compound and the second luminescent compound are mutually the same or different, a triplet energy of the first host material T1(H1) and a triplet energy of the second host material T1(H2) satisfy a relationship of Numerical Formula 1, and a diffusion coefficient D1 of the triplet energy of the first host material T1(H1) calculated according to a diffusion equation is 3.0×10−9 (cm2/s) or more,T1(H1)>T1(H2).(Numerical Formula 1)