OLED Display Panel Cathode Thickness Optimization
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Solution Overview
Problem
Current OLED display products suffer from color cast issues when viewed at large angles due to inconsistent luminance and hue of red, green, and blue lights, particularly exacerbated by the high L-Decay rate of blue light-emitting units.
Innovation Solution
A display panel design where each pixel unit includes light-emitting units with varying thicknesses of their second electrodes, with the blue light-emitting unit having the thinnest cathode to minimize adsorption force and improve transmittance, and auxiliary structures with different material proportions to control L-Decay curves consistency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the second electrode thickness is increased to improve manufacturing uniformity, then the manufacturing precision is improved, but the color cast at large viewing angles worsens due to excessive adsorption force on blue light-emitting units
Solution Approach 1:
The patent applies local quality by making the second electrode thickness vary across different light-emitting units within the same pixel unit. Specifically, the blue light-emitting unit has a thinner second electrode (10-20 nm) compared to red and green units (20-30 nm), allowing each unit to have optimized characteristics for its specific wavelength requirements while maintaining overall manufacturing feasibility
Solution Approach 2:
The patent changes the physical parameter of electrode thickness to resolve the contradiction. By reducing the thickness of the second electrode in blue light-emitting units, the adsorption force is reduced, improving light extraction efficiency and reducing color cast at large viewing angles, while still maintaining sufficient electrical functionality
2Object-affected harmful factors
If the second electrode thickness is decreased to reduce adsorption force on blue light, then the color cast is reduced, but the manufacturing precision deteriorates due to difficulty in controlling thin electrode formation
Solution Approach 1:
The patent implements local quality differentiation where the second electrode thickness is locally optimized for each light-emitting unit type (blue, green, red) within the pixel unit, with blue units having thinner electrodes (10-20 nm) and red/green units having thicker electrodes (20-30 nm), allowing tailored performance without compromising overall manufacturing control
Solution Approach 2:
The patent uses composite material structures in the auxiliary structures layer, combining materials with different properties (nucleation inhibition materials like TAZ/BAlq/Liq with nucleation promotion materials like C60/C70) to precisely control the nucleation and growth of the second electrode, enabling accurate thickness control even for thin electrodes
3Manufacturing precision
If auxiliary structures with high nucleation promotion are used to ensure uniform electrode formation, then the manufacturing precision is improved, but the L-Decay rate difference between colors worsens due to excessive adsorption on blue light units
Solution Approach 1:
The patent applies local quality by differentiating the composition of auxiliary structures across different light-emitting units. Blue light-emitting units have auxiliary structures with lower proportion of nucleation promotion materials (10-30%) compared to red and green units (30-50%), locally optimizing both electrode formation and light extraction characteristics for each unit type
Solution Approach 2:
The patent changes the compositional parameter of the auxiliary structures, specifically the ratio of nucleation inhibition materials to nucleation promotion materials, to precisely control the adsorption characteristics and electrode thickness for each light-emitting unit, thereby balancing manufacturing uniformity with optical performance
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 alleviates color deviation problems by ensuring consistent L-Decay trends across different color light-emitting units, thereby improving the display's color accuracy and reducing color cast at various viewing angles.
Implementation Method 1
an adsorption force of the first auxiliary structure of the light-emitting unit emitting light with the shortest wavelength on a material of the second electrode layer is the smallest
Implementation Method 2
the first material is a nucleation inhibition material for the material of the second electrode layer
Implementation Method 3
the second material is a nucleation promoting material for the material of the second electrode layer
Data Source
AI summary
The present disclosure provides a display panel, and belongs to the technical field of display. The display panel in the present application includes a base substrate and a plurality of pixel units on the base substrate. Each of the pixel units includes a plurality of light-emitting units emitting light in different colors. Each of the the plurality of light-emitting unit includes a first electrode, an organic functional layer and a second electrode stacked sequentially along a direction away from the base substrate. Among the plurality of light-emitting units emitting light in different colors in each pixel unit, the second electrode of the light-emitting unit emitting light with a shortest wavelength has a smallest thickness along a direction perpendicular to the base substrate.