Tandem Light Emitting Element Charge Generation Layer Optimization
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Solution Overview
Problem
Current light emitting elements in display devices face challenges in achieving high luminous efficiency and long lifespan, particularly in stabilizing the emission of light across different colors, which affects display efficiency and durability.
Innovation Solution
The implementation of a display device with a tandem structure comprising multiple light emitting regions and elements, each with specific layers such as hole transport regions, emission layers, and charge generation layers, where the thicknesses of p-type charge generation layers are optimized to satisfy a specific ratio, and the use of amine compounds in these layers to enhance hole transport and charge generation, leading to improved luminous efficiency and element lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a tandem structure with multiple light emitting units is used, then luminous efficiency is improved, but device complexity increases
Solution Approach 1:
The light emitting element is divided into multiple independent light emitting units (first, second, and third light emitting units), each capable of emitting different colors of light. Each unit contains its own emission layer, hole transport region, and electron transport region, allowing them to function semi-independently while contributing to overall luminous efficiency
Solution Approach 2:
The patent implements a nested structure where multiple light emitting units are stacked vertically within a single element. The first light emitting unit is positioned at the bottom, followed by the second light emitting unit in the middle, and the third light emitting unit at the top, with each unit nested within the same device structure sharing common electrodes and charge generation layers
2Productivity
If multiple light emitting regions with different colors are implemented, then display efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
Each light emitting unit is designed with specific local properties optimized for its intended color emission. The first light emitting unit uses materials and thickness configurations optimized for red light emission, the second for green light, and the third for blue light, allowing each region to have tailored characteristics for its specific function
Solution Approach 2:
The patent systematically varies key parameters across different light emitting units to achieve different color emissions. This includes adjusting the thickness of charge generation layers (with specific thickness ratios between units), modifying emission layer compositions, and changing material properties to shift emission wavelengths across the visible spectrum
3Duration of action of stationary object
If optimized charge generation layer thickness ratios are used, then element lifespan is improved, but device complexity increases
Solution Approach 1:
The patent establishes specific thickness ratios for charge generation layers between different light emitting units (with defined relationships between the thicknesses of charge generation layers in the first, second, and third units). These optimized parameter values balance charge distribution and reduce degradation mechanisms, thereby extending element lifespan
Solution Approach 2:
Charge generation layers serve as intermediary components between adjacent light emitting units, facilitating charge transfer and maintaining electrical neutrality. These intermediary layers mediate the interaction between different units, ensuring stable operation and reducing stress on individual units, which contributes to extended overall element lifespan
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 results in increased display efficiency by optimizing the emission of different colors, thereby enhancing the overall performance and longevity of the light emitting elements in display devices.
Implementation Method 1
a hole transport region, a first emission layer, and a first electron transport region, which are sequentially stacked
Implementation Method 2
Light emitting elements produce excitons by recombining holes and electrons respectively injected from a first electrode and a second electrode in an emission layer, and light is emitted when the excitons thus produced transition to a ground state
Implementation Method 3
the p-type charge generation layer may include an amine compound represented by Formula 1 and a p-dopant
Data Source
AI summary
Embodiments provide a display device that includes first, second, and third light emitting regions, and first, second, and third light emitting elements. The first, second, and third light emitting regions are spaced apart in a plan view. The first, second, and third light emitting elements respectively correspond to the first, second, and third light emitting regions. Each of the first, second, and third light emitting elements includes a first electrode, a second electrode, a first light emitting unit, a second light emitting unit, and a charge generation layer that includes a p-type charge generation layer and an n-type charge generation layer, wherein the p-type charge generation layer includes first, second, and third p-type charge generation layers.