OLED Pixel Defining Layer Structure for Light and Gas Blocking

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Solution Overview

Problem

Organic light-emitting display devices are susceptible to damage from moisture, oxygen, and impurities, such as gases generated during manufacturing, which can degrade the lifespan and quality of the devices.

Innovation Solution

A display device structure incorporating a pixel defining layer with a first inorganic insulating layer and a second layer having low light transmittance in a specific wavelength band, which includes amorphous silicon or amorphous carbon-based materials, is used to prevent external light and potential outgassing from reaching the organic insulating layer, thereby minimizing defects in the OLED.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional single-layer pixel defining layer is used, then the device structure is simple, but external light and outgassing can reach the organic insulating layer causing defects

Engineering Contradiction:

ImproveOLED quality and lifespanVSAvoidpixel defining layer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The pixel defining layer is divided into multiple sub-layers (first pixel defining layer, second pixel defining layer, third pixel defining layer) with different functions. The first layer blocks light, the second layer prevents outgassing, and the third layer provides additional protection, collectively resolving the contradiction between reliability improvement and structural complexity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses composite material structure where different layers are made of different materials optimized for specific functions. The first pixel defining layer uses light-blocking materials, the second layer uses materials resistant to outgassing penetration, creating a composite barrier system that enhances overall reliability

Inventive Principle:

Principle #40Composite materials

2Reliability

If the second layer completely covers the organic insulating layer, then outgassing and light damage are prevented, but manufacturing precision requirements increase

Engineering Contradiction:

Improveprotection against outgassing and lightVSAvoidcoverage alignment of second layer

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The second pixel defining layer is designed to cover specific critical areas where outgassing and light penetration are most problematic, rather than requiring uniform coverage across the entire organic insulating layer. This localized protection approach reduces manufacturing precision requirements while maintaining reliability

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The pixel defining layers are formed with predetermined patterns and dimensions during the manufacturing process that anticipate and prevent potential damage paths. The layers are designed with sufficient overlap and coverage margins in advance to ensure protection without requiring ultra-precise alignment during assembly

Inventive Principle:

Principle #10Preliminary action

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 damage to the OLED by blocking external light and gases, leading to improved device quality and longevity by reducing outgassing-related defects.

Implementation Method 1

a second layer having less light transmittance in a first wavelength band than the first layer... The first wavelength band may be in a range of 10 nm to 400 nm

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

The second layer may include an amorphous carbon-based material that absorbs light in the first wavelength band

Methodology Applied

Scientific EffectLight absorption by amorphous carbon-based material: Absorption (EM radiation)

Data Source

PatentUS11616105B2Display device structure for reducing defects

Publication Date: 2023.03.28 SAMSUNG DISPLAY CO LTD

AI summary

Provided is a display device including an organic insulating layer; a pixel electrode on the organic insulating layer; a pixel defining layer configured to cover an edge of the pixel electrode, having an opening corresponding to the pixel electrode, the pixel defining layer including a first layer including an inorganic insulating material and a second layer having less light transmittance in a first wavelength band than the first layer; an intermediate layer on a portion of the pixel electrode exposed via the opening, and including an emission layer; and an opposite electrode on the intermediate layer.