Charge Generation Layer for OLED Voltage and Lifetime
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Solution Overview
Problem
Organic light emitting display devices face challenges in reducing operating voltage, improving light emission efficiency, external quantum efficiency, and extending lifetime, particularly due to issues with the charge generation layer's energy level differences and dopant diffusion affecting electron injection and stability.
Innovation Solution
Incorporating a charge generation layer with a compound featuring a phenanthroline core and triphenylene functional group in the N-type charge generation layer, which includes alkali metals or earth metals, to enhance electron mobility and prevent dopant diffusion, thereby improving electron injection and device stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a charge generation layer with PN junction structure is used, then current generation efficiency is doubled and charge distribution is facilitated, but energy level difference between P-type and N-type layers deteriorates electron injection property
Solution Approach 1:
The patent modifies the energy level parameters of the charge generation layer by introducing a specific compound with a core containing two nitrogen atoms and a functional group with crystallinity. This changes the energy level alignment between P-type and N-type layers, reducing the energy barrier for electron injection while maintaining the charge generation functionality.
Solution Approach 2:
The patent uses a composite molecular structure combining a phenanthroline core with a triphenylene functional group. This composite material approach allows optimization of both charge generation capability and electron injection properties by leveraging the specific electronic and structural characteristics of the combined molecular components.
2Productivity
If N-type charge generation layer is doped with alkali metal dopant, then charge generation performance is improved, but dopant diffusion into P-type layer occurs leading to lifetime decrease
Solution Approach 1:
The patent introduces a compound with a specific molecular structure as an intermediary between the dopant and the P-type charge generation layer. The functional group with crystallinity acts as a barrier that prevents dopant diffusion into the P-type layer while still allowing the dopant to fulfill its charge generation function in the N-type layer.
Solution Approach 2:
The patent applies local quality by creating a spatially distinct molecular structure where the dopant is confined to the N-type layer region. The compound's specific structure ensures that the dopant remains localized where it is needed for charge generation, preventing unwanted diffusion into the P-type layer and extending device lifetime.
3Ease of manufacture
If conventional charge generation layer materials are used, then device fabrication is straightforward, but operating voltage remains high and light emission efficiency is limited
Solution Approach 1:
The patent changes the material parameters by introducing a compound with specific electronic properties (core with two nitrogen atoms) and structural characteristics (functional group with crystallinity). This modifies the electrical characteristics of the charge generation layer, enabling lower operating voltage and improved light emission efficiency while maintaining fabrication simplicity.
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 solution reduces operating voltage, increases light emission efficiency, and significantly extends the device's lifetime by facilitating better electron transport and preventing dopant diffusion, resulting in improved performance and longevity.
Implementation Method 1
A charge generation layer is formed between the first light emitting part and the second light emitting part to double the efficiency of current generated in the light emitting layers and facilitate charge distribution. The charge generation layer is a layer that generates a charge, i.e., electrons and holes, in it.
Implementation Method 2
the charge generation layer comprises a compound that includes a core with two nitrogen atoms and a functional group having crystallinity... the compound is included in the N-type charge generation layer... enhance electron mobility and prevent dopant diffusion, thereby improving electron injection and device stability
Implementation Method 3
The N-type charge generation layer preferably further comprises a dopant, and the dopant includes one among an alkali metal, an alkali earth metal, an alkali metal compound, an alkali earth metal compound, an organic complex of alkali metals, or an organic complex of alkali earth metals
Data Source
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AI summary
An organic light emitting display device is disclosed. The organic light emitting display device comprising at least two or more light emitting parts (ST1, ST2) each comprising a light emitting layer (140, 190) and an electron transport layer (150, 200); and a charge generation layer (160) between the at least two or more light emitting parts, wherein the charge generation layer comprises a compound that includes a core with two nitrogen atoms and a functional group having crystallinity.