OLED Multi-Layer Stack Sidewall Coverage
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Solution Overview
Problem
OLED displays face issues with screen abnormalities in the outskirts of the panel due to direct contact between the charge generation layer and the cathode electrode, leading to inefficiencies in current usage and lifespan.
Innovation Solution
A multi-layer stack structure is implemented, featuring a charge generation layer between the anode and cathode electrodes, with common layers covering the sidewalls of the charge generation layer to prevent direct contact and enhance emission efficiency, including a first and second stack with organic light-emitting layers and common layers to manage charge flow effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the charge generation layer is disposed between stack structures and the cathode electrode covers the stack structures, then the device structure is simplified and manufacturing is easier, but direct contact between the charge generation layer and cathode electrode causes screen abnormalities in the outskirt part
Solution Approach 1:
The patent introduces a contact blocking unit as an intermediary layer between the charge generation layer and the cathode electrode. This contact blocking unit prevents direct contact between these two layers, thereby eliminating screen abnormalities in the outskirt part while maintaining the simplified multi-layer stack structure. The contact blocking unit acts as a mediator that resolves the harmful interaction between the charge generation layer and cathode electrode.
2Device complexity
If the cathode electrode directly contacts the charge generation layer, then the device structure is simpler, but current efficiency decreases and lifespan is reduced due to short circuits and stress on driving elements
Solution Approach 1:
The contact blocking unit serves as a mediator that prevents direct contact between the cathode electrode and charge generation layer, thereby preventing short circuits and improving current efficiency. Although this adds a layer to the device structure, it resolves the harmful direct contact and enables efficient current flow through the intended pathways.
Solution Approach 2:
The patent segments the device structure by introducing the contact blocking unit as a separate functional layer. This segmentation divides the device into distinct functional zones: the charge generation layer for charge production, the contact blocking unit for preventing harmful contact, and the cathode electrode for charge collection. This segmentation improves current efficiency by ensuring current flows through the intended pathways.
3Device complexity
If the cathode electrode directly contacts the charge generation layer, then the device structure is simpler, but screen abnormalities occur in the outskirt part of the panel
Solution Approach 1:
The contact blocking unit acts as a mediator that prevents direct contact between the cathode electrode and charge generation layer, thereby eliminating screen abnormalities in the outskirt part of the panel. This intermediary layer is specifically positioned to address the harmful effects that occur at the edges and outskirts of the display panel.
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 configuration improves current efficiency and lifespan by preventing short circuits and reducing stress on driving elements, allowing for high brightness with reduced power consumption and uniform light emission across the display.
Implementation Method 1
The OLED emits light due to energy from excitons which are formed in an excitation process when holes and electrons injected into the anode electrode and the cathode electrode are recombined in the light emission layer EML
Data Source
AI summary
An organic light-emitting diode (OLED) display comprises, an anode electrode disposed over a substrate; a cathode electrode disposed opposite the anode electrode; a charge generation layer disposed between the anode electrode and the cathode electrode; a first stack disposed between the charge generation layer and the cathode electrode and configured to comprise a first organic light-emitting layer, a first common layer disposed over the first organic light-emitting layer, and a second common layer disposed under the first organic light-emitting layer; and a second stack disposed between the charge generation layer and the anode electrode, wherein at least one of the first common layer and the second common layer covers a sidewall of the charge generation layer.