Split Electrode Light-Emitting Element for Stable Gray Scale Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Display devices with light-emitting elements like OLEDs and QLEDs face challenges in achieving stable linear voltage and brightness characteristics, especially at low gray scales, leading to significant brightness variation across the display surface, and accelerated degradation due to time division driving methods.
Innovation Solution
A light-emitting element configuration with a specific electrode structure and charge transport layers, where the electrodes are split into multiple regions with different areas and polarities, allowing for stable voltage and brightness control across various gray scales without time division driving, and a display device circuit to switch these electrodes based on input image signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If time division driving (PWM driving) is used to display low gray scale, then brightness control is achieved, but brightness variation in the display surface increases and service life of light-emitting elements deteriorates
Solution Approach 1:
The light-emitting element is divided into multiple independent light-emitting regions (first region, second region, third region, fourth region) that can be controlled separately. Each region has its own electrode configuration and charge transport layers, allowing independent emission control to achieve gray scale without time division driving.
Solution Approach 2:
Different regions have different electrode areas and charge transport layer configurations to create localized variations in emission characteristics. The second electrode has a larger area than the first electrode, and the fourth electrode has a smaller area than the third electrode, creating distinct local emission zones with different properties.
2Illumination intensity
If current restriction is used to display low gray scale, then brightness control is achieved, but stable linear voltage and brightness characteristics cannot be obtained
Solution Approach 1:
The light-emitting element is divided into multiple independent light-emitting regions (first region, second region, third region, fourth region) that can be controlled separately. Each region has its own electrode configuration and charge transport layers, allowing independent emission control to achieve gray scale without time division driving.
Solution Approach 2:
The electrode configurations are designed with different areas (second electrode larger than first, fourth electrode smaller than third) to dynamically adjust the electrical field distribution across different regions, enabling stable voltage and brightness characteristics across various gray scales.
3Stability of the object's composition
If multiple electrodes with different areas are used to create stable voltage characteristics, then brightness stability improves, but device complexity increases
Solution Approach 1:
The light-emitting element is divided into multiple independent light-emitting regions (first region, second region, third region, fourth region) that can be controlled separately. Each region has its own electrode configuration and charge transport layers, allowing independent emission control to achieve gray scale without time division driving.
Solution Approach 2:
The multiple electrodes serve multiple functions: they create distinct light-emitting regions, control electrical field distribution, enable gray scale display, and extend service life. This multi-functionality justifies the increased structural complexity by eliminating the need for time division driving circuits.
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 enables stable linear voltage and brightness characteristics across the entire gray scale range, reducing brightness variation and extending the service life of the light-emitting elements by optimizing the electrical field distribution and emission regions.
Implementation Method 1
a light-emitting element including: a light-emitting layer; an upper electrode provided on a first side of the light-emitting layer; and a lower electrode provided on a second side of the light-emitting layer opposite to the first side
Implementation Method 2
a first charge transport layer and a second charge transport layer are provided between the lower electrode and the light-emitting layer. A third charge transport layer facing the first charge transport layer and a fourth charge transport layer facing the second charge transport layer are provided between the upper electrode and the light-emitting layer
Data Source
AI summary
A light-emitting element includes a light-emitting layer, an upper electrode provided on a first side of the light-emitting layer, and a lower electrode provided on a second side of the light-emitting layer opposite to the first side. The lower electrode is constituted by a first electrode and a second electrode including a first gap therebetween, the second electrode having an area larger than that of the first electrode. The upper electrode is constituted by a third electrode and a fourth electrode including a second gap therebetween, the third electrode facing the first electrode and the second electrode, the fourth electrode facing the second electrode and having an area smaller than that of the third electrode.