Electro-Optical Device Overhang Partition Wall for Aperture and Luminance
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Solution Overview
Problem
In electro-optical devices with narrow pixel intervals, light emitted from the light-emitting layer is shielded by the partition wall, leading to reduced aperture ratio and increased current density, which shortens the luminance life and causes issues like burn-in.
Innovation Solution
The use of a partition wall structure with an overhang design, where the upper portion protrudes from the partition wall, allows self-aligned formation of light-emitting layers and maintains an optimal angle (20-40 degrees) to balance aperture ratio and luminance, reducing light shielding and enhancing light efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the interval between pixel portions is narrowed to increase resolution, then the display density is improved, but light emitted from the light-emitting layer is shielded by the partition wall, reducing aperture ratio and luminance
Solution Approach 1:
The partition wall is designed with a protruding upper portion that extends in the vertical dimension (perpendicular to the substrate). This three-dimensional structure creates an overhang configuration where the upper portion protrudes from the main body of the partition wall, allowing light to pass underneath rather than being blocked by a flat vertical surface.
Solution Approach 2:
The partition wall structure is segmented into two functional parts: the main body portion that provides electrical isolation and the protruding upper portion that provides light shielding. This segmentation allows each part to perform its specific function optimally while working together to resolve the contradiction between narrow pixel intervals and light transmission.
2Productivity
If the partition wall height is increased to improve light shielding, then light extraction efficiency is improved, but the aperture ratio is reduced due to the upper portion blocking light
Solution Approach 1:
The partition wall features an asymmetric profile with a protruding upper portion that extends further in one direction than the other. This asymmetric design creates an overhang structure where the upper portion protrudes from the partition wall, allowing light to pass through the opening while still providing effective light shielding at the boundaries between pixel portions.
Solution Approach 2:
The solution transitions from a two-dimensional flat partition wall to a three-dimensional structure with a protruding upper portion. This dimensional change allows the partition wall to provide both light shielding and maintain aperture ratio by utilizing the vertical space above the light-emitting layer without blocking the light path.
3Area of stationary object
If the opening region is enlarged to increase aperture ratio, then light transmission is improved, but voltage unevenness due to resistance components increases
Solution Approach 1:
The protruding upper portion of the partition wall acts as an intermediary structure that maintains the necessary electrical isolation between pixel portions while allowing the opening region to be enlarged. The upper portion provides the light-shielding function that would otherwise require a taller partition wall, enabling a larger opening without compromising voltage uniformity.
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 design maintains high aperture ratio and luminance while extending the luminance life of the light-emitting layer, preventing burn-in and ensuring efficient light extraction.
Implementation Method 1
a light-emitting layer 132 provided between the first electrode 133 and the second electrode 131, 171 and being in contact with the second electrode 131, 171 in the opening 104a
Implementation Method 2
an upper portion 163 provided so as to protrude from the partition wall 161 in cross-sectional view on an upper surface of the partition wall 161 and having a light-shielding property against light emitted by the light-emitting layer 132
Data Source
AI summary
An electro-optical device includes a substrate, a pixel electrode, a light-emitting layer in contact with the pixel electrode in plan view at an opening region defined by an opening end, a common electrode that sandwiches the light-emitting layer with the pixel electrode, a conductive partition wall being in contact with the common electrode and surrounds the pixel electrode, the light-emitting layer, and the common electrode in plan view, and an upper portion provided on the upper surface of the partition wall to protrude from the partition wall in cross-sectional view. When a distance of a Z-direction component of a straight line coupling a tip of the upper portion to the opening end is defined as α and a distance of a component of the straight line along a substrate surface is defined as β, there is a relationship of α>β.