Organic EL Display Aperture Ratio via Electrode Superposition
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Solution Overview
Problem
The aperture ratio of organic electroluminescent (EL) display devices is limited by the narrow region of the organic emitting layer (EML) formed within the pixel electrode layer, which degrades the display efficiency.
Innovation Solution
The first electrode layer of the EL element is superimposed on the power source line with an insulation film in between, allowing for a wider formation of the organic EML and increasing the aperture ratio by forming an aperture on a third insulation film spaced from the power source line, thereby enhancing the light-emitting area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the organic EML is formed within the pixel electrode layer, then the device structure is simple, but the aperture ratio is limited and light-emitting efficiency is reduced
Solution Approach 1:
The organic EML is extended from a two-dimensional plane within the pixel electrode layer to a three-dimensional configuration that overlaps with the power source line in the vertical direction. This dimensional change allows the EML to occupy additional space above the power source line, effectively increasing the light-emitting area without expanding the horizontal footprint, thereby improving aperture ratio while maintaining structural simplicity.
2Area of stationary object
If the first electrode layer is extended to overlap with the power source line, then the aperture ratio is improved, but the insulation requirement must be maintained
Solution Approach 1:
An insulation film is introduced as an intermediary layer between the first electrode layer and the power source line. This intermediary maintains electrical isolation and prevents short circuits while allowing the first electrode layer to extend and overlap with the power source line in the vertical direction, thus enabling increased light-emitting area without compromising insulation performance.
3Area of stationary object
If the aperture of the third insulation film is spaced from the power source line, then the organic EML can be formed more extensively, but the manufacturing precision requirement increases
Solution Approach 1:
The insulation film is formed first to cover the power source line, creating a predefined insulation structure. Subsequently, the aperture of the third insulation film is formed at a predetermined position spaced from the power source line. This preliminary action of forming the insulation film first establishes a reliable reference structure that simplifies the subsequent positioning of the aperture, reducing the actual manufacturing precision requirements during the aperture formation step.
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 the aperture ratio and light-emitting efficiency of the organic EL display device by allowing a more extensive organic EML formation without affecting the power source line, resulting in better image display capabilities.
Implementation Method 1
The organic EL display device, which is a display device for electrically exciting a fluorescent organic compound to emit light
Data Source
AI summary
An electroluminescent display device includes a display panel having scan lines, data lines, and pixel circuits. The pixel circuit includes an electroluminescent element having a first electrode layer, a first insulation film, and an emitting layer for displaying images. A driving circuit is coupled to the electroluminescent element. The first electrode layer is superimposed on a power source line, a scan line, or both, with a second insulation film therebetween.