OLED Protective Layer Convex Pattern Offset Ink-Jet Sagging
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Solution Overview
Problem
OLED display devices face issues with light extraction efficiency and lifetime due to thickness non-uniformity of the organic light emitting layer caused by sagging during the ink-jet printing process, leading to increased operating voltage and reduced performance.
Innovation Solution
A protective layer with a convex protruding pattern is integrated into the light emitting area of the OLED display device, offsetting the sagging organic light emitting layer and ensuring uniform thickness across the substrate, formed simultaneously with the protective layer using a selective etching process, eliminating the need for a separate mask and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the organic light emitting layer is formed by ink-jet printing method, then manufacturing cost is reduced and flexibility is improved, but thickness non-uniformity occurs due to sagging at the central portion of the substrate
Solution Approach 1:
The patent applies preliminary action by forming a protruding pattern on the protective layer before depositing the organic light emitting layer. This protruding pattern pre-compensates for the expected sagging that will occur during ink-jet printing, ensuring that the final thickness is uniform across the substrate including the central portion where sagging typically occurs.
Solution Approach 2:
The patent implements local quality by creating a non-uniform protruding pattern with varying heights at different locations on the protective layer. The pattern has higher protrusions at the central portion of the substrate where sagging is more severe, and lower or no protrusions at the edge portions, thereby providing location-specific compensation for thickness non-uniformity.
2Quantity of substance
If the organic light emitting layer sags at the central portion of the substrate, then material usage is reduced, but light extraction efficiency decreases and operating voltage increases
Solution Approach 1:
The protruding pattern is formed in advance on the protective layer to prevent the organic light emitting layer from sagging. This preliminary structural support ensures uniform thickness distribution, maintaining optimal light extraction efficiency and operating voltage characteristics while using the exact amount of organic material needed without waste from excessive deposition.
3Manufacturing precision
If a separate mask is used to form the protruding pattern, then manufacturing precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the formation of the protective layer and the protruding pattern into a single integrated process. The protruding pattern is formed directly on the protective layer using the same ink-jet printing or coating process, eliminating the need for separate mask alignment and pattern formation steps. This reduces manufacturing complexity while maintaining the precision needed for thickness uniformity.
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 achieves maximum thickness deviation of 10A or less between central and edge portions, enhancing light extraction efficiency and extending the OLED display device's lifetime by maintaining uniform thickness and reducing operating voltage concerns.
Implementation Method 1
In such an OLED, in an excitation process when a hole and an electron injected into the anode electrode (anode) and cathode electrode (cathode) are recombined in the EML (emission layer), an exciton is formed, and it emits a light due to an energy from the exciton.
Data Source
AI summary
An organic light-emitting diode (OLED) display device capable of improving light extraction efficiency and lifetime is disclosed. In the OLED display device, a protective layer having a convex shaped protruding pattern is arranged in a light emitting area at a central portion of a substrate, so that only the light emitting area has a selectively convex protruding shape. Accordingly, in the OLED display device, in a process of forming an organic light emitting layer, the protruding pattern can artificially offset the organic light emitting layer arranged at the central portion of the substrate being sagged, by a protective layer having a convex shaped protruding pattern. As a result, the OLED display device can improve a problem of thickness non-uniformity of the central portion and an edge portion of the substrate due to a sagging phenomenon of the organic light emitting layer.