Electroluminescent Display Pixel Dam Planarization
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Solution Overview
Problem
The existing electroluminescent (EL) display devices face a decrease in emission efficiency and lifespan due to thickness deviations in the emitting layer formed by the solution process, which affects the uniformity and performance of the display.
Innovation Solution
The implementation of a pixel dam structure surrounding each pixel region on the substrate, with an overcoat layer having a flat top surface, ensures uniform thickness of the emitting layer by confining the organic insulating material and preventing step differences, thus maintaining emission efficiency and extending the lifespan of the EL display device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the emitting layer is formed by the solution process, then the manufacturing complexity is reduced, but the thickness uniformity and emission efficiency deteriorate
Solution Approach 1:
The patent introduces an intermediate layer between the substrate and the emitting layer formed by solution process. This intermediate layer acts as a mediator that provides a flat surface for the solution-processed emitting layer, preventing thickness deviations while maintaining the ease of solution processing. The intermediate layer compensates for the roughness of the underlying structure, enabling uniform emission without requiring complex thermal deposition equipment.
2Ease of manufacture
If the emitting layer is formed by the solution process, then the production cost is reduced, but the emission efficiency and lifespan deteriorate
Solution Approach 1:
The patent employs a spin coating process (a fluid dynamic technique) to form the emitting layer through solution processing. This hydraulic approach allows uniform thin film formation at low cost while maintaining emission efficiency. The rotating substrate creates centrifugal force that distributes the solution uniformly, preventing thickness variations that would otherwise reduce device reliability and lifespan.
3Shape
If an uneven top surface is present, then the structure follows the underlying layer topology, but the emitting layer thickness uniformity deteriorates
Solution Approach 1:
The patent introduces an intermediate layer between the substrate and the emitting layer formed by solution process. This intermediate layer acts as a mediator that provides a flat surface for the solution-processed emitting layer, preventing thickness deviations while maintaining the ease of solution processing. The intermediate layer compensates for the roughness of the underlying structure, enabling uniform emission without requiring complex thermal deposition equipment.
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
The solution effectively prevents thickness deviations in the emitting layer, enhancing the emission efficiency and lifespan of the EL display device by ensuring a uniform thickness and flat top surface, thereby improving the overall performance and durability of the display.
Implementation Method 1
an overcoat layer in contact with the pixel dam, the overcoat layer having a planar top surface
Implementation Method 2
an emitting diode on the overcoat layer and including a first electrode, a second electrode, and an emitting layer between the first electrode and the second electrode
Data Source
AI summary
An electroluminescent display device includes a plurality of pixels that each comprise a portion of a substrate. A pixel dam is disposed over an intermediate layer over the substrate. An overcoat layer is in contact with the pixel dam, the overcoat layer having a planar top surface. An emitting diode is on the overcoat layer and includes a first electrode, a second electrode, and an emitting layer between the first electrode and the second electrode.