OLED Thin Film Encapsulation with UV-Blocking Layer
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Solution Overview
Problem
OLED displays with thin film encapsulation (TFE) structures face challenges in effectively protecting the organic light emitting elements from environmental moisture and oxygen, leading to degradation, particularly at the edges of the encapsulation layer.
Innovation Solution
The implementation of a thin film encapsulation structure that alternately deposits inorganic and organic layers, with the organic layers being thicker and covering the inorganic layers, and the inclusion of a photo-functional UV-blocking layer between the organic light emitting element and the encapsulation portion, which enhances protection and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thin film encapsulation structure is used to protect the organic light emitting element, then the display maintains flexibility and thinness, but the protection from environmental moisture and oxygen is insufficient, leading to degradation
Solution Approach 1:
The patent employs a composite encapsulation structure consisting of alternating inorganic layers (silicon oxide, silicon nitride) and organic layers (polymer materials). This multi-material composite approach creates synergistic protection where inorganic layers provide barrier properties against moisture and oxygen permeation, while organic layers provide flexibility and stress relief, collectively solving the contradiction between protection effectiveness and flexibility maintenance.
Solution Approach 2:
The encapsulation structure is segmented into multiple thin layers (typically 5-20 nm each) rather than using a single thick layer. This segmentation into alternating inorganic and organic layers increases the tortuous path for moisture and oxygen permeation while maintaining overall film flexibility. Each layer contributes specifically to either barrier performance or mechanical flexibility, resolving the contradiction between protection and flexibility.
2Length of moving object
If the encapsulation layer is made thinner to maintain flexibility, then the display remains thin and flexible, but the edge protection becomes insufficient, leading to deterioration
Solution Approach 1:
The patent applies different layer thicknesses and material compositions at different locations within the encapsulation structure. The inorganic layers are positioned to provide enhanced barrier protection at critical edge regions, while organic layers provide flexibility throughout. This local optimization of layer properties ensures adequate edge protection even when the overall encapsulation thickness is reduced to maintain display flexibility.
Solution Approach 2:
The patent transitions from considering only the vertical thickness dimension to optimizing the horizontal lateral coverage and layer stacking arrangement. By designing the encapsulation structure with proper lateral extension beyond the active area and using alternating layer stacking, the patent achieves effective edge protection through dimensional optimization rather than simply increasing overall thickness.
3Reliability
If inorganic layers are deposited to provide barrier protection, then moisture and oxygen permeation is reduced, but the organic layers need to be thicker for flexibility, increasing overall thickness
Solution Approach 1:
The patent optimizes the thickness parameters of individual layers to achieve the desired balance. Inorganic layers are deposited at thicknesses of 5-20 nm to provide effective barrier protection, while organic layers are deposited at 10-30 nm to provide flexibility. The alternating stack architecture allows these thin individual layers to collectively provide both barrier and flexibility functions without requiring excessive overall thickness, as each layer type contributes its specific functional parameter.
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
This approach significantly reduces the permeation of moisture and oxygen, thereby extending the lifespan and improving the efficiency of OLED displays by preventing degradation and maintaining the display's flexibility and thinness.
Implementation Method 1
The organic layers may be an ultraviolet (UV) hardening material, and the optical thickness of the first layer and the second layer is λ/4 of the wavelength of the ultraviolet (UV) used to harden the organic layers.
Implementation Method 2
A photo-functional layer disposed between the organic light emitting element and the encapsulation portion may be further included, and the photo-functional layer may be an ultraviolet (UV) ray blocking layer.
Implementation Method 3
The implementation of a thin film encapsulation structure that alternately deposits inorganic and organic layers
Data Source
AI summary
An organic light emitting diode (OLED) display is disclosed. In one embodiment, the OLED display includes an organic light emitting element formed over a substrate and an encapsulation portion covering the organic light emitting element. Further, the encapsulation portion may include at least one organic layer and at least one inorganic layer, wherein ends of the inorganic layer and the organic layer directly contact the substrate, and wherein the organic layer is thicker than the inorganic layer.