Segmented Top Electrode for OLED Brightness Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In organic electroluminescence (EL) display devices with top emission configuration, the large resistance of metal or transparent conductive oxide electrodes leads to voltage drops and irregularities in brightness, especially as current increases to enhance image brightness and as display size grows.
Innovation Solution
The introduction of auxiliary lines connected to the top electrode, with a discharge effect generated between these lines to reduce voltage drops and improve brightness uniformity, involves forming auxiliary electrodes and lines on a substrate, with an organic light emitting layer between the top electrode and these auxiliary structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the top electrode is made of thin film metal or transparent conductive oxide to enable light transmission, then optical transmittance is improved, but electrical resistance increases causing voltage drop and brightness irregularities
Solution Approach 1:
The top electrode is divided into multiple segments (first top electrode segment, second top electrode segment, third top electrode segment) arranged in a matrix pattern. This segmentation reduces the resistance of each individual electrode segment while maintaining optical transmittance, as the smaller segments require less current to achieve the same brightness level.
Solution Approach 2:
Different regions of the display are equipped with different electrode segments that can be independently controlled. The segmentation allows local adjustment of current distribution, enabling compensation for brightness irregularities in specific areas while maintaining overall brightness uniformity across the display.
2Illumination intensity
If the current is increased to enhance image brightness, then illumination intensity is improved, but voltage drop increases causing brightness irregularities
Solution Approach 1:
By dividing the top electrode into multiple segments, the total current required to achieve a given brightness level is distributed across multiple parallel paths. This reduces the current through each individual segment, thereby reducing voltage drop and maintaining brightness uniformity even at higher overall brightness levels.
Solution Approach 2:
Multiple electrode segments are electrically connected in parallel to form a combined electrode system. This merging of multiple low-resistance paths creates an equivalent low-resistance electrode that can deliver high current with minimal voltage drop, enabling high brightness while maintaining uniformity.
3Area of stationary object
If the display device size is increased, then display area is improved, but voltage drop increases causing brightness irregularities
Solution Approach 1:
The top electrode is segmented into multiple smaller electrodes distributed across the entire display area. This segmentation ensures that no single electrode segment spans the entire large distance, thereby minimizing resistance and voltage drop even in large displays. Each segment remains compact with low resistance.
Solution Approach 2:
Instead of using a single planar electrode layer, the invention introduces a three-dimensional arrangement with multiple electrode segments at different positions. This dimensional approach allows current to flow through multiple parallel paths, effectively reducing the equivalent resistance across the large 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 helps in maintaining consistent brightness across the display by reducing voltage drops and preventing irregularities, enhancing the overall performance and manufacturing yield of organic EL display devices.
Implementation Method 1
A discharge effect is generated between the auxiliary electrode and the second auxiliary line
Data Source
AI summary
A display device includes a substrate. A pixel electrode is disposed on the substrate. An auxiliary electrode is disposed on the substrate. A first auxiliary line is connected to the auxiliary electrode. A second auxiliary line is spaced apart from the auxiliary electrode. A top electrode contacts at least one of the auxiliary electrode, the first auxiliary line, or the second auxiliary line. An organic light emitting layer is disposed between the top electrode and the pixel electrode, and is disposed between the top electrode and the first and second auxiliary lines.