OLED Spacer Thermal Expansion Breaks Light Emitting Layers

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Solution Overview

Problem

Large-size OLED display panels face the issue of lateral leakage between subpixels due to the communication of light emitting layers, leading to uneven display and reduced contrast, primarily caused by the charge generation layer allowing electron transmission between adjacent subpixels.

Innovation Solution

Incorporating a spacer with a higher thermal expansion coefficient than the light emitting layer into the display panel's groove structure, which separates the light emitting layers by expanding and breaking them during the manufacturing process, preventing lateral leakage and ensuring uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the light emitting layer is continuous across subpixels, then the manufacturing process is simpler, but lateral leakage occurs between subpixels causing uneven display and reduced contrast

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoiddisplay uniformity and contrast

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The light emitting layer is segmented into discrete subpixel regions by introducing groove structures between adjacent subpixels. These grooves physically separate the light emitting layers, preventing lateral leakage of electrons and charge carriers while maintaining manufacturing feasibility through batch processing of the segmented structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The groove structure acts as an intermediary barrier between adjacent subpixels. By introducing this intermediate structure filled with insulating material, the patent prevents direct communication between light emitting layers of neighboring subpixels, thereby eliminating lateral leakage while preserving the overall continuity of the display panel structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If a groove structure is introduced to separate subpixels, then lateral leakage is prevented, but the device structure becomes more complex

Engineering Contradiction:

Improvedisplay uniformity and contrastVSAvoidstructural complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The groove structures are implemented as thin film features integrated into the existing layer structure of the OLED panel. By using thin film fabrication techniques, the grooves add minimal structural complexity while effectively preventing lateral leakage, maintaining a relatively simple overall device architecture.

Inventive Principle:

Principle #30Flexible shells and thin films

3Manufacturing precision

If the spacer is made with high thermal expansion coefficient material, then the light emitting layer is effectively broken at the spacer, but the thermal stress on other layers increases

Engineering Contradiction:

Improvelight emitting layer separationVSAvoidthermal stress resistance

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The spacer is constructed from materials with high thermal expansion coefficients that exceed those of adjacent layers. During thermal processing, the spacer expands more than surrounding structures, creating mechanical stress that fractures the light emitting layer at the spacer location. This ensures complete electrical isolation between subpixels while the groove structure geometry is designed to manage and distribute thermal stresses.

Inventive Principle:

Principle #37Thermal expansion

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 lateral leakage between subpixels, resulting in improved display uniformity and contrast by ensuring each subpixel operates independently, enhancing the overall display performance.

Implementation Method 1

a thermal expansion coefficient of the spacer is greater than a thermal expansion coefficient of the light emitting layer

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS11444138B2Display panel, fabrication method therefor, and display device

Publication Date: 2022.09.13 BEIJING BOE TECH DEV CO LTD

AI summary

A display panel, a manufacturing method thereof and a display device are provided. The display panel includes a base substrate, a pixel definition layer, a light emitting layer and a spacer. The pixel definition layer is configured to define each of subpixels in the display panel and includes a groove structure which is disposed between adjacent subpixels, the spacer is disposed in the groove structure, the light emitting layer is disposed on a side of the pixel definition layer and the spacer away from the base substrate, and a thermal expansion efficient of the spacer is greater than a thermal expansion efficient of the light emitting layer.