OLED Pixel Define Layer Protrusion Structures for Film Uniformity

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Solution Overview

Problem

Existing OLED display technologies face challenges in achieving uniformity of the light emitting functional layer due to differences in surface tension distribution and migration distances within the sub-pixel light emitting area, leading to uneven film thickness and light emission.

Innovation Solution

The implementation of a pixel define layer with protrusion structures on its sides facing the hollow, combined with a multi-layer structure and inkjet printing of the light emitting functional layer, adjusts the surface tension and redistributes stress during the drying process, optimizing film uniformity and preventing edge thickening.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a conventional pixel define layer structure is used, then the manufacturing process is simple, but the light emitting functional layer exhibits non-uniform thickness and edge thickening

Engineering Contradiction:

Improveuniformity of light emitting functional layerVSAvoidstructure of pixel define layer

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The pixel define layer is divided into multiple layers (first pixel define layer and second pixel define layer) with different surface tension characteristics. The first layer provides a base structure while the second layer with protrusion structures controls the surface tension distribution, segmenting the functions to achieve both uniformity and controlled complexity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Protrusion structures are added at specific locations (on sides facing the hollow) of the pixel define layer to locally modify surface tension distribution. This local structural modification addresses the edge thickening problem without requiring complete redesign of the entire layer structure

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If inkjet printing is used to form the light emitting functional layer, then the manufacturing flexibility is improved, but the film uniformity is compromised due to surface tension distribution issues

Engineering Contradiction:

Improvefilm thickness uniformityVSAvoidinkjet printing process control

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The surface tension parameter of the pixel define layer is modified by adding protrusion structures and using different materials (lyophilic and lyophobic materials) in different regions. This changes the surface tension distribution to compensate for the Marangoni effect during inkjet printing, enabling uniform film formation while maintaining printing flexibility

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The pixel define layer acts as an intermediary between the substrate and the light emitting functional layer. By controlling its surface tension distribution through protrusion structures, it mediates the inkjet printing process to achieve uniform film deposition without requiring complex printing process control

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If the pixel define layer has uniform surface properties, then the manufacturing is easier, but the light emitting functional layer shows non-uniform stress distribution during drying

Engineering Contradiction:

Improvestress distribution uniformityVSAvoidpixel define layer fabrication

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The pixel define layer is designed with asymmetric surface properties - the first layer has different surface tension characteristics than the second layer. The protrusion structures on the second layer create asymmetric local surface tension distribution that specifically addresses stress concentration at edges during the drying process

Inventive Principle:

Principle #4Asymmetry

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 approach enhances the uniformity of the organic light emitting film layer, reduces edge climbing phenomena, and ensures consistent light emission by adjusting surface tension and migration patterns, thereby improving the overall display performance.

Implementation Method 1

adjusts the surface tension and redistributes stress during the drying process

Methodology Applied

Scientific EffectSurface tension: Surface Tension

Implementation Method 2

adjusts the surface tension and redistributes stress during the drying process, optimizing film uniformity

Methodology Applied

Scientific EffectMarangoni effect: Marangoni Effect

Implementation Method 3

forming, by inkjet printing, a light emitting functional layer within the hollow and on the base substrate on which the pixel define layer is formed

Methodology Applied

Scientific EffectInkjet printing:

Data Source

PatentUS10784322B2Array substrate, manufacturing method, and display device

Publication Date: 2020.09.22 BOE TECHNOLOGY GROUP CO LTD

AI summary

Embodiments of the present disclosure provide an array substrate, a manufacturing method, and a display device. The array substrate comprises: a pixel define layer located on a base substrate, the pixel define layer having a hollow for defining a sub-pixel light emitting area, and a light emitting functional layer located in the hollow, wherein, the pixel define layer has protrusion structures on one or more sides facing the hollow.