OLED Auxiliary Electrode Voltage Distribution
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Solution Overview
Problem
Existing OLED display technologies face challenges in achieving uniform luminance due to voltage drops across the cathode electrode, which affects the aperture ratio and image quality, particularly in top emission type OLEDs.
Innovation Solution
The OLED display device incorporates a second electrode connected to an auxiliary electrode, with the second electrode insulated from the charge generation layer, ensuring uniform voltage distribution and luminance across the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional OLED structure with a single electrode connected to the charge generation layer is used, then the device structure is simple, but voltage drops occur across the cathode electrode causing non-uniform luminance
Solution Approach 1:
The electrode system is segmented into a first electrode connected to the charge generation layer and a second electrode connected to an auxiliary electrode. This segmentation allows the voltage distribution to be divided into two separate paths, preventing voltage drops across a single cathode electrode and ensuring uniform luminance across the display device.
Solution Approach 2:
The auxiliary electrode acts as an intermediary between the second electrode and the charge generation layer. It provides an additional electrical connection point that helps distribute voltage uniformly across the OLED structure, eliminating the need for a long cathode electrode that would cause voltage drops.
2Reliability
If the second electrode is directly connected to the charge generation layer, then electrical connection is straightforward, but leakage currents occur affecting image quality
Solution Approach 1:
The direct connection between the second electrode and the charge generation layer is extracted and replaced with an indirect connection through the auxiliary electrode. This separation prevents leakage currents from flowing directly through the charge generation layer, thereby improving image quality and reducing unwanted electrical paths.
3Area of stationary object
If the aperture ratio is increased to improve display area, then more light can be emitted, but voltage control becomes difficult leading to non-uniform luminance
Solution Approach 1:
The electrical connection is moved from a planar dimension (direct connection across the charge generation layer) to a vertical dimension (connection through the auxiliary electrode positioned above or below). This dimensional change allows for larger aperture ratios while maintaining uniform voltage distribution and luminance control across the 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 configuration enhances the uniformity of luminance and reduces leakage currents, resulting in improved image quality and aperture ratio in OLED displays.
Implementation Method 1
an organic light emitting diode (OLED)... a first light emitting portion on the first electrode... a second light emitting portion on the first charge generation layer
Data Source
AI summary
An organic light emitting diode display device includes an auxiliary electrode spaced apart from a plurality of first electrodes on a substrate. A first light emitting portion is on the first electrode. A charge generation layer is on the first light emitting portion. A second light emitting portion is on the charge generation layer. A second electrode is on the second light emitting portion and is electrically connected to the auxiliary electrode. The second electrode is insulated from the charge generation layer.