OLED Encapsulation Using Porous Layer and Low Melting Point Glass
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Solution Overview
Problem
Organic light emitting display devices face challenges with residual moisture and solvent accumulation, leading to dark spots and pixel shrinkage due to the lack of effective encapsulation structures that can prevent external moisture and contaminants from infiltrating and causing degradation.
Innovation Solution
An encapsulation structure comprising a first porous layer with a curved top surface, a first planarization layer with a flat top surface, and a first barrier layer made of low melting point glass, which includes tin-phosphate glass, tin-borophosphate glass, or tin-fluorophosphate glass, is used to encapsulate the organic light emitting structure. This structure includes a second porous layer and additional barrier layers to enhance moisture absorption and prevent residual solvent concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional encapsulation structure is used, then the device structure is simple, but residual moisture and solvent accumulate leading to dark spots and pixel shrinkage
Solution Approach 1:
The encapsulation structure is divided into multiple functional layers: a first porous layer for moisture absorption, a first planarization layer for surface flattening, and a first barrier layer for moisture blocking. This segmentation allows each layer to perform its specific function effectively, preventing residual moisture and solvent accumulation that causes dark spots and pixel shrinkage.
Solution Approach 2:
The encapsulation structure uses composite materials with different properties: the porous layer uses materials with high porosity for moisture absorption, the planarization layer uses materials for surface flattening, and the barrier layer uses low melting point glass for moisture blocking. This combination of materials with complementary properties solves the reliability problem while managing structural complexity.
2Reliability
If multiple encapsulation layers are added to prevent moisture infiltration, then reliability improves, but manufacturing complexity increases
Solution Approach 1:
The barrier layer uses low melting point glass that can be deposited at lower temperatures and processed more easily than conventional high melting point glass. This parameter change in the material properties simplifies the manufacturing process while maintaining effective moisture barrier performance across multiple layers.
Solution Approach 2:
The planarization layer acts as an intermediary between the porous layer and the barrier layer, providing a flat surface that facilitates easier deposition of subsequent layers. This intermediary layer simplifies the manufacturing process by ensuring proper surface preparation without requiring complex alignment or surface treatment procedures.
3Productivity
If the barrier layer is deposited directly on the porous layer, then manufacturing steps are reduced, but the barrier layer thickness is non-uniform due to curved surface
Solution Approach 1:
The planarization layer is deposited beforehand on the porous layer to create a flat surface. This preliminary action ensures that the subsequent barrier layer can be deposited with uniform thickness, eliminating the problem of non-uniform deposition on curved surfaces while maintaining manufacturing efficiency.
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 encapsulation structure effectively prevents residual moisture and solvent accumulation, reduces the risk of dark spots and pixel shrinkage, and improves the reliability of the organic light emitting display device by using low melting point glass for defect removal through heat treatment, ensuring uniform thickness and high density of the barrier layers.
Implementation Method 1
The first porous layer above a substrate has a curved top surface. The first planarization layer on the first porous layer has a flat top surface. The first porous layer may include a plurality of pores, and the plurality of pores may receive a residual moisture or a residual solvent from the first planarization layer.
Implementation Method 2
The first barrier layer on the first planarization layer includes a low melting point glass. The first low melting point glass may have a melting point below about 400° C.
Data Source
AI summary
An encapsulation structure for an organic light emitting display device, an organic light emitting display device, and a method of manufacturing an organic light emitting display device are provided. The encapsulation structure includes a first porous layer, a first planarization layer, and a first barrier layer. The first porous layer above a substrate may have a curved top surface. The first planarization layer on the first porous layer may have a flat top surface. The first barrier layer on the first planarization layer may include a low melting point glass.