OLED Cathode Contact Area Reduction via Planarization Opening
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Solution Overview
Problem
Current OLED displays face issues with high IR-drop due to high resistance of cathode electrodes, which is not efficiently addressed by adding auxiliary electrodes, leading to increased manufacturing complexity and reduced efficiency.
Innovation Solution
A method for manufacturing OLED displays that involves forming an auxiliary electrode, a planarization layer, a transparent conductive layer, and a pixel defining layer, with the cathode electrode partially covering the auxiliary electrode via an opening, reducing the contact area and eliminating the need for isolation columns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large contact area between cathode electrode and auxiliary electrode is used, then electrical conductivity is improved, but manufacturing complexity increases due to the need for isolation columns
Solution Approach 1:
The patent extracts and removes the isolation columns from the device structure entirely. Instead of using isolation columns to define the contact area between the cathode electrode and auxiliary electrode, the invention uses a planarization layer with a through-hole to directly expose the auxiliary electrode in the non-display area, eliminating the need for isolation columns and simplifying the device structure.
Solution Approach 2:
The patent changes the approach from using vertical isolation columns (3D structure) to using a planarization layer with a through-hole (2D planar approach). The contact area is defined by the opening in the planarization layer rather than by vertical isolation structures, transitioning from a three-dimensional isolation approach to a two-dimensional planar definition.
2Manufacturing precision
If isolation columns are formed between cathode electrode and auxiliary electrode, then manufacturing precision is improved, but productivity decreases due to increased manufacturing steps
Solution Approach 1:
The patent merges the functions of the planarization layer and the isolation structure into a single component. The planarization layer serves both to flatten the surface for subsequent layer deposition and to define the contact area through its through-hole, eliminating the need for separate isolation columns and reducing the number of manufacturing steps.
Solution Approach 2:
The planarization layer is given multiple functions: it provides surface planarization for subsequent layer deposition and simultaneously defines the contact area between the cathode electrode and auxiliary electrode through its through-hole. This multi-functional approach reduces the number of components and manufacturing steps required.
3Loss of energy
If cathode electrode contact area with auxiliary electrode is reduced, then IR-drop is lowered, but electrical conductivity worsens
Solution Approach 1:
The patent applies local quality by creating a non-uniform contact area between the cathode electrode and auxiliary electrode. The contact area is concentrated in the non-display area through the through-hole of the planarization layer, allowing the cathode electrode to have minimal contact (reducing IR-drop in display area) while still maintaining adequate electrical connection through the localized contact region in the non-display area.
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 lowers IR-drop and simplifies the manufacturing process by reducing the contact area between the cathode and auxiliary electrodes, thereby enhancing manufacturing efficiency and reducing costs.
Implementation Method 1
forming an organic light emitting layer on the pixel defining layer by evaporation
Data Source
AI summary
The present disclosure provides an OLED display and a method for manufacturing the same. The method comprises steps of forming a planarization layer on the auxiliary electrode, wherein the planarization layer includes an opening; forming a transparent conductive layer and a pixel defining layer on the planarization layer, and patterning the same, such that both the transparent conductive layer and the pixel defining layer is located above the opening to shield a side of the opening that is adjacent to a non-display area; and forming a cathode electrode on the pixel defining layer by evaporation, such that the cathode electrode partially covers a side of the auxiliary electrode.