Scattering Bumps on OLED Electrodes for Light Extraction
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Solution Overview
Problem
Organic light-emitting display devices suffer from low light efficiency, with only about 20% of emitted light escaping, while 80% is lost internally, necessitating a structure to enhance light output.
Innovation Solution
A method of manufacturing a display device involves forming scattering bumps on the electrode layer using anisotropic dry etching with a carbon-containing etching gas, creating a concave-convex pattern that increases light efficiency without altering color coordinates, and includes a metallic oxide electrode layer with inorganic insulating materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional flat electrode layer structure is used, then the manufacturing process is simple, but light efficiency is low with only 20% of emitted light escaping
Solution Approach 1:
The patent applies curvature by forming scattering bumps with convex surfaces on the electrode layer. These curved microstructures scatter light in multiple directions, increasing the probability of light extraction from the OLED device. The spherical/convex shape of the bumps creates multiple reflection paths for trapped light, thereby improving light efficiency without requiring complete structural redesign
Solution Approach 2:
The patent transitions from a two-dimensional flat electrode layer to a three-dimensional structured surface by adding scattering bumps. This dimensional change introduces vertical microstructures that create additional light extraction pathways, converting the previously planar interface into a micro-relief surface that enhances light coupling efficiency
2Loss of energy
If scattering structures are added to improve light efficiency, then light extraction is enhanced, but white angular dependency increases
Solution Approach 1:
The patent applies local quality by creating localized scattering centers (bumps) with specific size distributions and spatial arrangements. Rather than uniform scattering throughout, the bumps are formed with controlled dimensions (typically 0.1-10 micrometers) that provide optimized scattering properties. This localized structuring allows tailored light manipulation that maintains color consistency while improving extraction efficiency
Solution Approach 2:
The patent utilizes parameter changes by controlling the physical dimensions, material composition, and density of scattering bumps. By adjusting bump height, radius, spacing, and material refractive index, the scattering characteristics are tuned to achieve optimal light extraction while minimizing angular dependency effects on color coordinates
3Loss of energy
If complex patterning processes are used to create scattering structures, then light efficiency improves, but manufacturing complexity and cost increase
Solution Approach 1:
The patent applies preliminary action by forming the scattering bump pattern during the existing photolithography and etching processes used for pixel definition. The same photoresist layers and etch masks used to define pixel electrodes are utilized to simultaneously create the scattering bump patterns, eliminating the need for separate patterning steps and reducing manufacturing complexity
Solution Approach 2:
The patent merges multiple functions into a single structural element. The scattering bumps are integrated with the electrode layer formation process, combining the electrode patterning function with the light scattering function. This consolidation allows both the electrode pattern and scattering structure to be created in the same manufacturing sequence, reducing process steps
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 method improves white angular dependency and light efficiency by scattering light effectively, maintaining color coordinate stability, thereby enhancing the display device's performance.
Implementation Method 1
The etching may be an anisotropic dry etching
Implementation Method 2
the etching may include using an etching gas including carbon
Implementation Method 3
forming a plurality of scattering bumps by removing the second layer of each of the plurality of fine patterns
Data Source
AI summary
A method of manufacturing a display device includes forming an electrode layer including a first metallic element on a substrate; sequentially forming an insulating layer including a first material and a photosensitive pattern layer including a first pattern on the electrode layer; forming a plurality of fine patterns including a first layer that includes the first material and a second layer by etching the photosensitive pattern layer and the insulating layer; and forming a plurality of scattering bumps by removing the second layer of each of the plurality of fine patterns.