OLED Pixel Electrode Layout Using Dummy Patterns for Contact Hole Relief
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In display apparatuses, the thick planarization layer between the drain electrode and anode electrode results in a steep angle of the contact hole, reducing the emission layer thickness and potentially causing short-circuiting of the cathode electrode, which decreases the opening ratio and stability of the emission region.
Innovation Solution
The introduction of dummy patterns under the contact hole in the emission region allows the drain electrode to extend and connect with the light emitting device in a second emission region, reducing the step height of the contact hole and increasing the opening ratio, thereby stabilizing the light emitting device formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a contact hole is formed in a thick planarization layer to connect the drain electrode and anode electrode, then the opening ratio of the emission region can be increased, but the angle between the lateral surface and lower surface of the contact hole increases, causing the emission layer thickness to decrease or cathode electrode short-circuiting
Solution Approach 1:
The emission region is divided into a first emission region (where the TFT is located) and a second emission region (where dummy patterns are located). The contact hole is specifically formed in the second emission region, separating the electrical connection function from the active emission area. This segmentation allows the contact hole to be positioned where it does not interfere with the emission layer thickness in the first emission region, thus maintaining emission layer quality while achieving electrical connection and increasing overall opening ratio.
2Manufacturing precision
If the planarization layer thickness is reduced to decrease contact hole depth, then the contact hole angle improves, but the planarization function may be compromised
Solution Approach 1:
Instead of reducing the planarization layer thickness in the vertical dimension, the solution moves the contact hole formation to a different horizontal location (the second emission region with dummy patterns). This dimensional shift allows the contact hole to be formed in an area where the planarization layer can be thinner without compromising the overall planarization function in the first emission region, thus improving contact hole geometry while maintaining planarization effectiveness.
Data Source
AI summary
A display apparatus including a substrate; a thin film transistor (TFT) provided on a first emission region of the substrate; a plurality of dummy patterns provided on a second emission region of the substrate adjacent to the first emission region; a planarization layer provided on the TFT and the plurality of dummy patterns; and a light emitting device including a first electrode provided on the planarization layer, an emission layer provided on the first electrode, and a second electrode provided on the emission layer. Further, a drain electrode of the TFT extends from the first emission region to the second emission region and is electrically connected with the first electrode of the light emitting device.