OLED Display Panel Variable Doping Charge Balance
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Solution Overview
Problem
Traditional single-layer RGB OLED devices struggle to meet high brightness and long life requirements due to defects at the electron-generating layer (n-CGL) and hole-generating layer (p-CGL) interface, leading to high driving voltage, low efficiency, and short service life, especially at extreme temperatures.
Innovation Solution
A display panel structure with variable doping concentrations in the electron-generating and hole-generating layers, where n-type dopant concentrations decrease and p-type dopant concentrations increase in a specific direction, reducing the formation of space charge regions and stabilizing charge balance, thereby preventing interface reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If stacked RGB or W devices with more complex structures are used to meet high brightness and long life requirements, then light-emitting efficiency is improved several times compared to single-layer devices, but device complexity increases and manufacturing difficulty increases
Solution Approach 1:
The patent applies local quality by creating a charge-generating layer with non-uniform doping concentration distribution. Specifically, the doping concentration varies in the thickness direction, with different concentrations at different depths of the layer. This local variation in doping concentration optimizes charge generation and separation at different interfaces within the stacked structure, improving light-emitting efficiency without requiring further structural complexity
Solution Approach 2:
The patent changes the doping concentration parameter within the charge-generating layer to optimize device performance. By adjusting the doping concentration distribution (creating a gradient from higher to lower concentration in the thickness direction), the device achieves better charge balance and reduced interface defects, thereby improving efficiency while maintaining manageable structural complexity
2Illumination intensity
If stacked light-emitting devices operate at high temperatures, then brightness can be maintained, but driving voltage increases, efficiency decreases, and service life decreases due to interface defects between electron-generating and hole-generating layers
Solution Approach 1:
The patent changes the doping concentration parameter in the charge-generating layer to improve high-temperature reliability. By establishing a doping concentration gradient (higher concentration near the electron-generating layer interface, lower concentration toward the hole-generating layer interface), the device maintains better charge balance at elevated temperatures, reducing interface defect formation and improving service life stability while maintaining brightness
Solution Approach 2:
The patent applies beforehand cushioning by pre-optimizing the doping concentration distribution in the charge-generating layer before device operation. This pre-designed gradient structure anticipates high-temperature operating conditions and prevents interface defect formation by ensuring proper charge balance from the outset, thereby cushioning against the degradation that would otherwise occur at high temperatures
3Ease of manufacture
If uniform doping concentration is used in electron-generating and hole-generating layers, then manufacturing process is simpler, but interface defects form more easily at high or low temperatures, leading to charge imbalance and reduced device performance
Solution Approach 1:
The patent transitions from uniform to non-uniform doping concentration distribution in the charge-generating layer. By implementing local quality variation (different doping concentrations at different positions within the layer, particularly varying in the thickness direction), the device achieves better charge balance stability across temperature ranges while maintaining reasonable manufacturing complexity through controlled deposition processes
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 enhances the stability and efficiency of the OLED device at high and low temperatures, extending service life and reducing driving voltage, suitable for harsh environments.
Implementation Method 1
the electron-generating layer includes n-type dopants, and the hole-generating layer includes p-type dopants; in the first direction, the n-type dopants in the electron-generating layer has a plurality of doping concentrations, and the plurality of doping concentrations of the n-type dopants in the electron-generating layer tend to decrease in the first direction
Data Source
AI summary
Embodiments of the present disclosure disclose a display panel and a mobile terminal. The display panel includes a light-emitting layer. The light-emitting layer includes a first electrode, a hole injection layer, a first light-emitting unit layer, an electron-generating layer, a hole-generating layer, a second light-emitting unit layer, and a second electrode stacked in sequence. By adopting the technical solutions of the present disclosure, the light-emitting device of the display panel can operate at high temperatures or low temperatures with high current efficiency without changing the structure of the light-emitting layer.