OLED Spacer Geometry for Reliable Electrode Contact
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Solution Overview
Problem
In organic light emitting display devices, poor contact between the contact electrode connected to the transistor's source or drain and the upper electrode on the spacer leads to black dot defects and abnormal operations due to inadequate sealing of the substrates.
Innovation Solution
The organic light emitting display device incorporates a first spacer with an upper surface area of 0.5% to 20% of the subpixel area, ensuring proper contact between the first contact electrode and the upper electrode, and a slop of 30° to 70° to maintain a stable connection and prevent damage from external pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first substrate and second substrate are sealed together using a conventional spacer, then the device structure is simple and manufacturing is easy, but poor contact occurs between the contact electrode and upper electrode causing black dot defects
Solution Approach 1:
The patent changes the geometric parameters of the spacer, specifically setting the upper surface area to 0.5% to 20% of the subpixel area and the slop angle to 30° to 70°, to optimize contact between electrodes while maintaining structural simplicity
Solution Approach 2:
The spacer is designed with non-uniform geometry, having different surface areas at different heights (larger lower surface area for stability, smaller upper surface area for precise contact), creating local quality variations that simultaneously ensure structural support and reliable electrical contact
2Reliability
If the spacer upper surface area is too small, then contact area is reduced improving opening rate, but contact reliability deteriorates causing black dot defects
Solution Approach 1:
The patent establishes specific parameter ranges: upper surface area of 0.5% to 20% of subpixel area and slop angle of 30° to 70°, which balance contact reliability and opening rate by optimizing the spacer's geometric dimensions
Solution Approach 2:
The spacer provides more than minimal contact area (0.5% of subpixel area) to ensure reliable contact, while keeping it less than excessive (20% limit) to maintain high opening rate, achieving optimal balance through partial action
3Manufacturing precision
If the spacer has a steep slop angle, then contact precision is improved, but structural stability under external pressure deteriorates
Solution Approach 1:
The patent optimizes the slop angle parameter to range from 30° to 70°, where angles within this range provide sufficient contact alignment precision while maintaining structural stability to withstand external pressure during sealing
Solution Approach 2:
The slop angle is set to provide more than minimal precision (30° minimum) while avoiding excessive steepness (70° maximum) that would compromise structural stability, achieving optimal balance through partial action
Data Source
AI summary
Provided is an organic light emitting display device. The organic light emitting display device comprises a first substrate, a second substrate facing the first substrate, a transistor on the first substrate, a first contact electrode disposed on the transistor and connected to a source or a drain of the transistor, a subpixel on the second substrate, and a first spacer projected to make an upper electrode included in the subpixel to be in contact with the first contact electrode. An upper surface area of the first spacer is about 0.5% to 20% of an upper surface area of the subpixel.