Insulating Layer Pixel Definition for OLED Edge Open Defects
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Solution Overview
Problem
The existing laser-induced thermal imaging (LITI) method for forming organic layers in organic light-emitting display devices often results in 'edge open' defects due to gaps at the edges of the organic layer, leading to non-uniform luminance and product defects.
Innovation Solution
Incorporating an insulating layer between the emissive layer and other layers within the organic light-emitting display device, which functions as a pixel-defining layer to prevent edge open defects, and using the LITI method to transfer and pattern this layer for precise light emission area definition without the need for an additional pixel-defining layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a pixel-defining layer is formed to surround the pixel electrode boundary, then the pixel area is regulated, but gaps are created at the edge portion of the organic layer due to the thickness of the pixel-defining layer
Solution Approach 1:
The pixel-defining layer and the organic layer are merged into a single integrated structure. The pixel-defining layer is formed with a first thickness at the boundary and a second thickness (greater than the first) at the light emission area, creating a stepped structure that eliminates gaps while maintaining precise pixel area regulation.
Solution Approach 2:
The pixel-defining layer transitions from a single-plane structure to a multi-level stepped structure by varying thickness in the vertical dimension. This dimensional change allows the layer to simultaneously define pixel boundaries and prevent edge gaps without requiring additional surrounding layers.
2Measurement precision
If the LITI method is used to transfer the organic layer, then the organic layer is precisely patterned, but gaps are formed at the edge portion due to the step portion created by the pixel-defining layer thickness
Solution Approach 1:
The pixel-defining layer and organic layer are formed as an integrated stepped structure, eliminating the interface gap that would otherwise occur between separate layers during LITI transfer. The organic layer is deposited conformally on the stepped pixel-defining layer, ensuring continuous coverage at edges.
3Ease of manufacture
If a pixel-defining layer with uniform thickness is used, then the manufacturing process is simple, but the adhesive properties between the organic layer and pixel electrode are reduced due to gaps at the edge
Solution Approach 1:
The pixel-defining layer exhibits spatially varying thickness with different local properties: a first thickness at the boundary region for easy fabrication and a second greater thickness at the light emission area for enhanced adhesion. This local differentiation maintains manufacturing simplicity while improving edge adhesive properties.
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 insulating layer effectively defines light emission areas in units of pixels, preventing edge open defects and ensuring uniform luminance by blocking hole and electron flow, thus enhancing the adhesive properties and manufacturing efficiency of the organic layer.
Implementation Method 1
a laser induced thermal imaging (LITI) method, which is a dry process through which minute patterns may be formed, is frequently used to form the organic layer. In the LITI method, a donor film on which an organic layer is deposited is placed on a pixel electrode such that the organic layer on the donor film is transferred to a pixel location by heat and laser is irradiated on the pixel electrode.
Implementation Method 2
an insulating layer that defines a light emission area of the emissive layer
Data Source
AI summary
An organic light-emitting display device and a method of manufacturing the same. The organic light-emitting display device has a structure including an organic layer between a pixel electrode and an opposite electrode, the organic layer including a emissive layer and an insulating layer defining a light emission area. Accordingly, the insulating layer included in the organic layer functions as a pixel-defining layer, and thus, “edge open”, which is generated when forming an emissive layer on a thick pixel-defining layer according to the comparable art, may be reduced or prevented.