Curved Hole Injection Layer for Uniform Organic EL Display Thickness
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Solution Overview
Problem
In organic EL display panels, the thickness of the light-emitting layer becomes non-uniform due to ink attraction to banks during the drying process, leading to decreased aperture ratio and shortened panel duration.
Innovation Solution
A concavely or convexly curved hole injection layer is used, with the banks having a forward-tapered shape, to ensure uniform thickness of the organic light-emitting layer, preventing ink intrusion and maintaining even light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If banks are used to define sub pixels and ink is applied inside the defined region, then ink intrusion into adjacent sub pixels is prevented, but the thickness of the light emitting layer becomes non-uniform due to ink attraction to banks during drying
Solution Approach 1:
The patent applies curvature to the banks by designing them with a specific arc shape rather than straight lines. This curved configuration modifies the capillary action and ink flow dynamics during the drying process, preventing ink from being excessively attracted to the bank edges. As a result, the light emitting layer maintains uniform thickness across the sub pixel area while still being properly confined by the banks, thereby improving both manufacturing precision and device reliability.
2Reliability
If the light emitting layer thickness is non-uniform, then the aperture ratio decreases and panel duration shortens, but making the layer uniform requires precise control of ink application and drying
Solution Approach 1:
The curved bank design simplifies the ink application process by passively controlling ink distribution through its geometric shape. Instead of requiring complex active control mechanisms for ink application and drying, the curved banks naturally guide the ink flow and evaporation process to achieve uniform thickness. This geometric solution reduces device complexity while ensuring reliable aperture ratio and panel duration.
3Productivity
If uniform light emitting layer thickness is achieved, then aperture ratio and light emission efficiency are improved, but the manufacturing process requires precise bank configuration
Solution Approach 1:
The curved bank configuration provides a built-in mechanism for achieving uniform ink distribution and light emitting layer thickness. The specific arc shape of the banks creates optimal capillary channels that guide ink flow and evaporation, eliminating the need for extremely precise bank positioning or configuration. This design enhances light emission efficiency while maintaining reasonable manufacturing tolerances for bank configuration.
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 results in a high aperture ratio and extended panel duration by maintaining uniform light-emitting layer thickness and reducing deterioration, enhancing light emission efficiency and panel longevity.
Implementation Method 1
the thickness of the light emitting layer becomes non-uniform due to ink attraction to banks during the drying process
Implementation Method 2
An organic EL device, which is a display device, is a light emitting element exploiting electro-luminescence of organic compounds
Data Source
Figure 1
Figure 2
Figure 3A~3I
AI summary
The present invention relates to an organic EL display panel having an organic light emitting layer having a uniform film thickness. The organic EL display panel of the present invention includes: a substrate; linear banks placed on the substrate and defining a linear region on the substrate; and at least two organic EL elements aligned in a row each linear region, and, each of the organic EL elements includes: an anode placed on the substrate; a hole injection layer formed with an metallic oxide and placed on the anode; an organic light emitting layer placed on the hole injection layer; and a cathode placed on the organic light emitting layer. The hole injection layer is concavely curved or convexly curved, the hole injection layer is partly placed under the banks; and the organic light emitting layer is formed by applying an organic light emitting material in the linear region.