Auxiliary Electrode Thickness Control in Large OLED Displays
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Solution Overview
Problem
Conventional organic light-emitting display apparatuses face challenges in manufacturing large-sized displays due to increased interconnection resistance of common electrodes, which complicates the manufacturing process and affects the efficiency of the display.
Innovation Solution
A thin film deposition apparatus using a small mask scanning (SMS) method to form both counter and auxiliary electrodes with different thicknesses, where the auxiliary electrode is electrically connected to the counter electrode, improving voltage drop and simplifying the manufacturing process by allowing relative movement between the substrate and mask during deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a common electrode covers all pixels in large-sized display apparatuses, then the display area is increased, but the interconnection resistance increases
Solution Approach 1:
The patent divides the common electrode into two separate electrodes: a counter electrode and an auxiliary electrode. This segmentation allows the auxiliary electrode to specifically address the interconnection resistance issue in large-sized displays while the counter electrode maintains the display function, thereby resolving the contradiction between large display area and high interconnection resistance.
Solution Approach 2:
The auxiliary electrode is designed with different thickness in different regions: thicker in non-light-emitting regions (to reduce interconnection resistance) and thinner or absent in light-emitting regions (to maintain display quality). This local quality variation optimizes electrical conductivity where needed without compromising the optical performance of the display areas.
2Reliability
If different thicknesses of counter electrode and auxiliary electrode are formed, then the voltage drop is improved, but the manufacturing process complexity increases
Solution Approach 1:
The patent combines the formation of counter electrode and auxiliary electrode into a single deposition process using a mask with multiple slits. This merging of operations allows different thicknesses to be achieved in one step, avoiding the need for separate deposition processes and thereby reducing manufacturing complexity while still improving voltage drop characteristics.
Solution Approach 2:
A single mask structure serves multiple functions: it defines both the counter electrode pattern and the auxiliary electrode pattern, and controls the thickness variation of the auxiliary electrode through its slit design. This multi-functionality simplifies the manufacturing process by eliminating the need for multiple masks or sequential patterning steps.
3Ease of manufacture
If a mask scanning deposition method is used, then the manufacturing process is simplified, but the precision of electrode thickness control may be compromised
Solution Approach 1:
The mask is designed in advance with specifically engineered slit configurations that predetermined the thickness profile of the auxiliary electrode. The slit widths and positions are calculated to produce the desired thickness distribution during a single scanning deposition pass, eliminating the need for post-deposition thickness adjustment and ensuring precise control while maintaining process simplicity.
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
This approach reduces the sheet resistance of the counter electrode and simplifies the manufacturing process for large-sized organic light-emitting display apparatuses, enhancing the voltage drop and efficiency while maintaining the thin profile and wide viewing angles of organic light-emitting displays.
Implementation Method 1
one or more deposition-based methods
Data Source
AI summary
A method of manufacturing an organic light-emitting display apparatus includes: forming light-emitting regions on a substrate; forming an organic light-emitting layer on the light-emitting regions; forming a counter electrode on the organic light-emitting layer; and forming an auxiliary electrode electrically connected to the counter electrode. A thickness of the auxiliary electrode is different from a thickness of the counter electrode. Formation of the counter electrode and formation of the auxiliary electrode are achieved via a small mask scanning (SMS) deposition method using the same mask.