Barrier Layer in EL Display Pixel Defining Layer
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Solution Overview
Problem
Conventional organic electroluminescent (EL) display devices face degradation due to outgases from the pixel defining layer, which affects the organic emission layer's luminance and color purity, and using an inorganic layer to mitigate this complicates the fabrication process.
Innovation Solution
Incorporating at least one barrier layer in the pixel defining layer to reduce outgas emission and prevent degradation, achieved through impurity injection or heat curing, thereby extending the device's lifespan and maintaining luminance and color purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inorganic layer is used as the pixel defining layer to reduce outgas, then the organic emission layer degradation is prevented, but the fabrication process becomes more complex
Solution Approach 1:
The pixel defining layer is constructed as a composite structure combining an organic insulating layer with an inorganic barrier layer formed on top of it. This composite approach provides the outgas barrier functionality of inorganic materials while maintaining the fabrication simplicity and optical properties of organic materials, thus preventing organic emission layer degradation without significantly complicating the fabrication process
Solution Approach 2:
The inorganic barrier layer is applied selectively only to the pixel defining layer regions where outgas control is critical, rather than using inorganic materials throughout the entire display structure. This localized application provides targeted protection against outgas while minimizing the overall complexity and material usage
2Object-generated harmful factors
If the pixel defining layer is hardened at high temperature to remove outgas, then outgas is reduced, but the organic emission layer may be damaged
Solution Approach 1:
The inorganic barrier layer is formed on the pixel defining layer before the organic emission layer is deposited. This preliminary barrier prevents outgas from reaching and damaging the organic emission layer during subsequent high-temperature hardening processes, allowing aggressive outgas removal without compromising emission layer integrity
Solution Approach 2:
The inorganic barrier layer acts as an intermediary between the pixel defining layer and the organic emission layer. It blocks the harmful outgas molecules generated during high-temperature processing from contacting the organic emission layer, thus enabling effective outgas removal while protecting the sensitive organic materials
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 barrier layer effectively minimizes outgas discharge, reducing pixel contraction and maintaining the EL display's performance by creating a longer discharge path for outgases, thus enhancing the device's operational stability and simplifying the fabrication process.
Implementation Method 1
at least one barrier layer disposed in and/or on the pixel defining layer... to reduce the amount of outgas from the pixel defining layer
Implementation Method 2
the pixel defining layer 12 may be hardened at temperature of about 230° C. to 280° C. by baking to remove outgas remaining in the pixel defining layer 12
Data Source
AI summary
An electroluminescent (EL) display device and a method of fabricating the same are provided. The device includes a substrate; a plurality of pixel electrodes disposed on the substrate; a pixel defining layer disposed on the pixel electrodes and having an opening part exposing a predetermined part of each of the pixel electrodes; and at least one barrier layer comprised in and/or on the pixel defining layer. In this device, the pixel defining layer includes at least one barrier layer in order to reduce the amount of outgas from the pixel defining layer and prevent degradation of an emission portion due to the outgas. Also, the pixel defining layer is formed to a sufficiently small thickness to facilitate a subsequent process using a laser induced thermal imaging (LITI) process.