Organic Electroluminescence Device with Heavy Atom Blocking Layer
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Solution Overview
Problem
Organic electroluminescence devices face luminance deterioration due to metallic ion diffusion during long-range storage and high-temperature preservation, which is not effectively addressed by existing diffusion-preventing layers.
Innovation Solution
An organic electroluminescence device with an n-type-dopant-containing electron transport layer and an n-type-dopant blocking layer, where the n-type-dopant blocking layer includes a heavy atom compound with an atomic weight of 79 or more, maintaining a volume ratio concentration equal to or higher than the n-type dopant in the electron transport layer to prevent ion diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the thickness of organic layers is decreased to reduce driving voltage, then driving voltage is reduced, but defective electricity between electrodes increases resulting in decreased product yields
Solution Approach 1:
The patent introduces doping with alkaline metals or alkaline earth metals into the charge transport layer to change the electrical parameters (conductivity) of the layer, allowing for reduced layer thickness while maintaining reliable electrical contact and preventing defective electricity between electrodes
Solution Approach 2:
The patent uses composite materials by combining organic compounds with alkaline metals or alkaline earth metals as dopants in the charge transport layer, creating a composite charge transport layer that achieves both low driving voltage and high reliability by preventing electrode defects
2Stress or pressure
If alkaline metal or alkaline earth metal is used as dopant to reduce driving voltage, then driving voltage is reduced, but handling difficulty increases due to deliquescence, absorbency and instability in air
Solution Approach 1:
The patent employs alkaline metals or alkaline earth metals as dopants that are highly effective for voltage reduction but have limited stability in air. These materials are processed in controlled environments (vacuum deposition or co-evaporation) and serve their purpose effectively despite their reactivity and handling challenges
Solution Approach 2:
The patent addresses the instability of alkaline metals and alkaline earth metals in air by employing vacuum deposition or co-evaporation techniques, creating an inert atmosphere during the doping process to prevent unwanted reactions while maintaining the dopant's effectiveness
3Reliability
If conventional diffusion-preventing layers are used to block metallic ion diffusion, then ion diffusion is partially blocked, but luminance deterioration still occurs during long-range storage and high-temperature preservation
Solution Approach 1:
The patent introduces an intermediary layer between the charge transport layer and the electrode, which acts as a barrier to metallic ion diffusion. This intermediate layer prevents ions from reaching and degrading the electrode or other functional layers, thereby maintaining luminance stability during long-term storage and high-temperature preservation
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 solution effectively prevents luminance deterioration and extends the device's lifespan by restricting the diffusion of metallic ions, maintaining consistent luminance even after 100 hours at high temperature, making it suitable for long-term storage and use.
Implementation Method 1
an n-type-dopant blocking layer having an interface with the n-type-dopant-containing electron transport layer to block the n-type dopant
Implementation Method 2
an n-type dopant of an electron donor being a metallic atom or ion thereof as a second component
Implementation Method 3
holes are injected from the source electrode as well as electrons are injected from drain electrode and these are recombined in the organic light-emitting layer so that excitons are generated. When the excitons return from an excited state to a ground state, light is emitted
Data Source
Figure 1~2
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Figure 5~6
AI summary
An organic electroluminescence device includes a plurality of organic semiconductor layers including an organic light-emitting layer and layered or disposed between a pair of anode and cathode opposed to each other. The device includes n-type-dopant-containing electron transport layer disposed between the cathode and the organic light-emitting layer. The n-type-dopant-containing electron transport layer includes an organic compound capable of transporting electrons as a first component which mixed with an n-type dopant of an electron donor of metallic atom or ion thereof as a second component. The organic electroluminescence device further includes an n-type-dopant blocking layer having an interface contacting with the n-type-dopant-containing electron transport layer to block the n-type dopant. The n-type-dopant blocking layer includes a heavy atom compound including at least one kind of heavy atoms with an atomic weight of 79 or more.