OLED Barrier Layer Floating Prevention via Localized Flattening
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Solution Overview
Problem
The existing organic electroluminescence (EL) display devices face reliability issues due to 'layer floating' phenomena, where the sealing layer is compromised by moisture penetration, leading to reduced yield and effectiveness of the sealing film.
Innovation Solution
The organic EL display device incorporates cliff-like banks with forward tapered slope faces and a sealing layer composed of silicon compound barrier layers and a polymerized flattening resin, which reduces the spread of organic material and minimizes the likelihood of layer floating by localizing the organic material in irregular portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an organic film is formed as the flattening layer over a substantially overall surface of the sealing layer area, then the irregularity of the barrier layer surface is smoothed, but the flattening layer is exposed from barrier layer defects and swells with moisture penetration causing layer floating
Solution Approach 1:
The patent applies local quality by forming the flattening layer only in specific localized areas (inner corners at steps of pixel edges) rather than over the entire sealing layer area. This selective placement smooths surface irregularities where they occur most while minimizing the total area of organic material that could be exposed to moisture and cause layer floating.
Solution Approach 2:
The patent extracts the flattening function from a comprehensive full-area coating and concentrates it only in the specific regions where irregularity occurs (inner corners at steps). This removes the harmful effect of widespread organic material exposure while preserving the beneficial surface smoothing effect where needed.
2Reliability
If the amount of organic material in the flattening layer is decreased to localize it in irregular portions, then the probability of layer floating is lowered, but the surface irregularity smoothing effect is reduced
Solution Approach 1:
The patent implements local quality by concentrating the organic material precisely where surface irregularities occur (inner corners at steps of pixel edges) rather than distributing it uniformly. This achieves effective smoothing at the locations that matter most while minimizing the total organic material present, thereby reducing layer floating risk.
Solution Approach 2:
The patent applies partial action by providing the flattening effect only to the extent necessary - specifically in the inner corners at steps where irregularity occurs - rather than applying it uniformly across the entire surface. This partial application is sufficient to achieve the required surface quality while minimizing harmful effects.
3Shape
If cliff-like banks with 90° or larger inclination angles are formed, then the pixel boundaries are clearly defined, but the upper electrode cannot be properly connected across pixel boundaries
Solution Approach 1:
The patent segments the upper electrode into multiple parts: pixel electrodes within pixels, boundary electrodes on bank tops, and slope electrodes on the tapered faces. This segmentation allows each electrode type to be optimized for its specific location and function, enabling proper electrical connection across the cliff-like bank structures.
Solution Approach 2:
The patent adds a dimensional solution by forming slope electrodes on the tapered slope faces of the banks, creating a three-dimensional electrode network that bridges the vertical gap between pixels. This multi-dimensional electrode arrangement overcomes the connectivity problem created by the steep cliff-like bank profiles.
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 enhances the reliability of the sealing layer by reducing the probability of layer floating, thereby improving the moisture protection and yield of the organic EL display devices.
Implementation Method 1
The acrylic monomer is adhered onto the surface of the first barrier layer 40 by vapor deposition or the like
Implementation Method 2
The acrylic monomer has fluidity, is aggregated on an irregular portion by surface tension, and makes the undulation of the irregular portion gentle
Implementation Method 3
The acrylic monomer is polymerized by the irradiation of ultraviolet rays into acrylic resin in a state where the irregularity is thus smoothed
Implementation Method 4
The sealing layer 16 has a moisture-proof function for protecting the OLED from moisture, for example, contained in the filler layer 8
Data Source
AI summary
In an organic EL display device configured in which an acrylic resin layer is disposed under a barrier layer that protects an OLED for flattening the barrier layer, floating the barrier layer caused by penetration of moisture into the acrylic resin can be prevented. A side surface of a bank formed in a boundary of pixels is formed into a cliff part having an inclination angle of 90° or larger in most portions of a circumstance of each pixel part, and formed into a gently sloped part having the inclination angle smaller than 90° in a part of the circumference. The electrode parts disposed within the respective pixels are connected to each other through an electrode part disposed on an upper surface of the bank, and electrode parts disposed on the gently sloped parts to form an OLED common electrode.