Dam Structure for OLED Encapsulation Overflow Control
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Solution Overview
Problem
Organic capping layers in OLED, LED, and QLED display panels are susceptible to water vapor and oxygen permeance, leading to overflow issues during thin film encapsulation, which affects the performance and lifespan of the display panels.
Innovation Solution
Incorporating a dam structure in the non-displaying areas of the display panels, specifically designed to control the boundary of the organic capping layer during encapsulation, thereby increasing the path length for water vapor and oxygen permeance and preventing overflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If organic capping layer is used for encapsulation, then flexibility and ease of manufacture are improved, but resistance to water vapor and oxygen permeance deteriorates
Solution Approach 1:
The patent employs a composite encapsulation structure combining organic capping layer with inorganic barrier layers (such as aluminum oxide, silicon oxide) and dam structures. This composite approach leverages the flexibility and ease of manufacturing organic materials while compensating for their permeability issues through inorganic barrier layers that block water vapor and oxygen transmission paths.
Solution Approach 2:
The encapsulation system is segmented into multiple functional layers: organic capping layer for flexibility and coverage, inorganic barrier layers for permeance resistance, and dam structures for boundary control. This segmentation allows each layer to perform its specialized function, collectively achieving both ease of manufacture and high reliability.
2Manufacturing precision
If dam structure height is increased to prevent overflow, then encapsulation boundary control is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes dam structure parameters (height, width, position) within specific ranges to achieve effective overflow prevention without excessive complexity. By carefully selecting parameter values that satisfy mathematical relationships, the system achieves precise boundary control while maintaining manufacturability and avoiding overly complex structures.
3Reliability
If dam structure is added to control encapsulation boundary, then resistance to water vapor permeance is improved, but device complexity increases
Solution Approach 1:
The dam structure serves as an intermediary element between the organic capping layer and the substrate, creating a physical barrier that extends the encapsulation boundary and prevents water vapor penetration. This intermediary structure effectively enhances reliability without requiring fundamental redesign of the entire device architecture.
Data Source
AI summary
A display panel includes a first inorganic capping layer (INOCL) in a non-displaying area (AND) of a substrate, a first electrode in the AND formed on the first INOCL, an organic capping layer (OCL) on the substrate overlapping at least a portion of the first electrode, and a first dam structure in the AND positioned between a first lateral surface of the substrate and the OCL in top view. A first distance H is between the top surfaces of the first INOCL and the OCL in a normal direction of the substrate. The first dam structure has a first maximum dam height Hdam and a dam width Wdam. A second distance Lsr is a minimum distance from a third lateral surface of the first dam structure to a second lateral surface of the first electrode, wherein H, Lsr, Hdam and Wdam conform to the equation: H×(0.1870−Wdam/(2.46×Lsr))≤Hdam≤H×(0.9548−Wdam/(44.26×Lsr)).