Auxiliary Electrode Height Variation in OLED Devices
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Solution Overview
Problem
In organic light emitting display devices, residual layers and foreign materials on the anode electrode surface reduce device lifetime and performance due to obstruction of hole movement and non-uniform layer formation, and existing surface treatment methods damage the hydrophobic bank surface, compromising the organic light emitting layer's restricted area function.
Innovation Solution
An auxiliary electrode with a higher refractive index than the organic light emitting layer is introduced on the anode electrode, and etched to have different heights under the bank and exposed areas, allowing for clean surface removal of residual layers and maintaining the hydrophobic bank surface integrity, enhancing light emission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If surface treatment technology using plasma or EUV is used to remove residual layers, then the residual layer including organic material or foreign material is removed, but the hydrophobic area of the bank surface is simultaneously removed
Solution Approach 1:
The patent segments the surface treatment process by introducing an auxiliary electrode that is selectively etched in specific regions. The auxiliary electrode is etched in the pixel area to remove residual layers, while the bank surface is protected from etching, thereby maintaining the hydrophobic characteristic. This segmentation allows different regions to undergo different treatments.
Solution Approach 2:
The auxiliary electrode serves as an intermediary structure between the anode electrode and the organic light emitting layer. It provides a clean surface for hole movement while protecting the bank's hydrophobic surface. The auxiliary electrode mediates the conflict between needing a clean surface and preserving the hydrophobic characteristic.
2Device complexity
If residual layer including organic material or foreign material remains on anode electrode, then device structure is simple, but hole movement is obstructed causing reduction in lifetime and performance
Solution Approach 1:
The patent segments the electrode structure by adding an auxiliary electrode layer between the anode electrode and the organic light emitting layer. This segmentation allows the auxiliary electrode to specifically address the residual layer problem without requiring complete restructuring of the entire device, thus maintaining relative simplicity while improving reliability.
Solution Approach 2:
The auxiliary electrode is extracted as a separate functional layer that specifically addresses the residual layer issue. By taking out this intermediate layer, the patent removes the harmful effect of residual layers on hole movement without affecting other parts of the device structure.
3Manufacturing precision
If auxiliary electrode is introduced and etched to have different heights, then clean surface is achieved and light emission efficiency is enhanced, but device complexity increases
Solution Approach 1:
The auxiliary electrode is designed with local quality variations, having different heights in different regions. The first auxiliary electrode has a first height in the pixel area and a second height (lower than the first height) in the non-pixel area. This local quality approach allows the electrode to provide different functions in different regions, achieving clean surface removal where needed while maintaining structural integrity elsewhere.
Solution Approach 2:
The auxiliary electrode serves multiple functions: it provides a clean surface for hole movement in the pixel area, maintains the hydrophobic characteristic of the bank surface in the non-pixel area, and enhances light emission efficiency. This multi-functionality justifies the added structural complexity.
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 auxiliary electrode ensures a clean surface for uniform organic light emitting layer and cathode formation, increases light emission efficiency, and extends the device's operational lifetime by preventing residual layer interference and maintaining the hydrophobic bank's functionality.
Implementation Method 1
etched to have different heights under the bank and exposed areas, allowing for clean surface removal of residual layers
Implementation Method 2
An auxiliary electrode with a higher refractive index than the organic light emitting layer is introduced on the anode electrode, and etched to have different heights
Implementation Method 3
an upper surface of the bank 3 is formed to have a hydrophobic characteristic. That is, in the soluble organic light emitting display device, the bank 3 restricts an area where the organic light emitting layer 5 is provided
Data Source
AI summary
An organic light emitting display device can include an anode electrode disposed on a substrate; an auxiliary electrode disposed on the anode electrode, the auxiliary electrode having a first height and a second height being different from the first height; a bank disposed on one side of the auxiliary electrode and another side of the auxiliary electrode; an organic light emitting layer disposed on an upper surface of the auxiliary electrode in an opening area exposed by the bank; and a cathode electrode disposed on the organic light emitting layer, in which the auxiliary electrode has the first height in a covered area overlapping with the bank and the second height in the opening area exposed by the bank.