Staircase Insulating Layer for Display Light Extraction
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Solution Overview
Problem
Current display apparatuses face challenges in achieving high light efficiency and quality due to limitations in light emission and reflection management, particularly in the design of insulating layers and encapsulation structures.
Innovation Solution
The display apparatus incorporates a substrate with a display area and peripheral area, featuring a first insulating layer with a staircase-shaped step and a second insulating layer of higher refractive index, along with a protruding dam and valley portions, to enhance light emission efficiency by optimizing the structure of insulating layers and encapsulation layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional flat insulating layer structure is used, then the manufacturing process is simple, but light emission efficiency is poor
Solution Approach 1:
The insulating layer is designed with a curved concave profile instead of a flat surface. The curvature radius increases from the pixel electrode toward the peripheral area, creating a lens-like structure that redirects oblique light emissions toward the normal direction, thereby improving light extraction efficiency without complicating the manufacturing process
Solution Approach 2:
The refractive index of the insulating layer is optimized to be higher than that of the encapsulation layer (e.g., insulating layer: 1.5-1.7, encapsulation layer: 1.4-1.6). This parameter change creates beneficial refraction at the interface, directing light outward and improving emission efficiency
2Loss of energy
If the insulating layer thickness is increased to improve light emission, then light efficiency improves, but filling defects increase
Solution Approach 1:
The concave curved profile with increasing curvature radius toward the periphery creates a self-aligning structure that guides filling material uniformly across the pixel area, preventing voids and ensuring complete filling even with increased thickness
Solution Approach 2:
The insulating layer profile is pre-formed with the optimal concave curvature before the filling process. This preliminary structuring ensures that subsequent filling operations proceed uniformly without defects, as the pre-formed geometry naturally guides material flow and distribution
3Device complexity
If a single-layer insulating structure is used, then device complexity is low, but light reflection management is insufficient
Solution Approach 1:
A single insulating layer is used with optimized parameters: refractive index between 1.5-1.7 and thickness of 50-200 nm. The layer's concave curved profile and refractive index parameters work together to manage light reflection and refraction, directing light outward while maintaining low device complexity
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 configuration improves light emission efficiency and luminance by effectively managing light reflection and emission, reducing defects in filling the insulating layers and enhancing the overall display quality.
Implementation Method 1
A second refractive index of the second insulating layer is greater than a first refractive index of the first insulating layer
Data Source
AI summary
A display apparatus includes a substrate including a display area and a peripheral area outside the display area, a display element arranged on the substrate in the display area, an encapsulation layer arranged on the display element, a first insulating layer arranged on the encapsulation layer and including a first opening that corresponds to a light-emitting area of the display element, and a second insulating layer covering the first insulating layer. A second refractive index of the second insulating layer is greater than a first refractive index of the first insulating layer, and a side surface of the first insulating layer defining the first opening includes a staircase-shaped step.