Tapered Insulating Layer for Display Leakage Current Reduction
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Solution Overview
Problem
Current display devices face challenges in achieving high-resolution, high-definition, and highly reliable manufacturing with efficient light extraction, particularly in large-sized displays for applications like VR and AR, where existing methods like metal mask evaporation result in low accuracy and damage to light-emitting layers.
Innovation Solution
The display device incorporates a structure with a first and second light-emitting device, insulating layers, and a common electrode, where the insulating layers have tapered ends and cover the light-emitting layers, and the use of photolithography for fine patterning without a shadow mask allows for high-resolution and reliable manufacturing, reducing leakage currents and improving aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If metal mask evaporation is used for manufacturing, then light extraction can be achieved, but manufacturing precision and reliability deteriorate due to low accuracy and damage to light-emitting layers
Solution Approach 1:
The patent replaces the mechanical metal mask evaporation process with a photolithography-based chemical deposition process. The insulating layer pattern is formed by photolithography (optical/chemical method) rather than mechanical mask alignment, eliminating the precision limitations of metal mask positioning and the risk of mechanical damage to organic light-emitting layers during mask removal.
2Ease of manufacture
If insulating layers with vertical ends are used, then manufacturing is simpler, but leakage currents increase and aperture ratio decreases
Solution Approach 1:
The patent introduces asymmetric tapering to the insulating layer structure. Instead of vertical ends, the insulating layer has a tapered profile where the thickness gradually decreases toward the edges. This asymmetric shape prevents direct contact between the common electrode and light-emitting layer at the boundaries, eliminating leakage current paths while maintaining manufacturing feasibility through standard deposition techniques.
3Manufacturing precision
If high-resolution patterning is achieved through conventional methods, then display quality improves, but damage to light-emitting layers increases
Solution Approach 1:
The patent introduces an insulating layer as an intermediary protective barrier during the patterning process. The insulating layer is formed first, then patterned by photolithography, and finally removed in a controlled manner. This intermediary structure allows high-resolution patterning to be achieved through the insulating layer without directly exposing and damaging the fragile organic light-emitting layers to harsh etching or mechanical processes.
4Productivity
If aperture ratio is increased for higher efficiency, then light extraction improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent replaces mechanical mask alignment with photolithographic patterning of the insulating layer. This substitution allows for more precise and flexible pattern definition, enabling larger aperture ratios to be achieved without compromising alignment precision. The photolithography process provides better control over pattern dimensions and positioning compared to mechanical mask methods.
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 enables the production of high-resolution, high-definition displays with improved reliability and increased aperture ratio, enhancing display quality and manufacturing yield while minimizing damage to light-emitting layers.
Implementation Method 1
the first insulating layer covers a side surface and part of a top surface of the first light-emitting layer and a side surface and part of a top surface of the second light-emitting layer
Implementation Method 2
the use of photolithography for fine patterning without a shadow mask allows for high-resolution and reliable manufacturing
Implementation Method 3
Light-emitting devices (also referred to as EL devices or EL elements) utilizing electroluminescence (hereinafter referred to as EL)
Data Source
AI summary
A display device with high display quality is provided. The display device includes a first light-emitting device, a second light-emitting device, a first insulating layer, and a second insulating layer; the first light-emitting device includes a first pixel electrode, a first light-emitting layer over the first pixel electrode, and a common electrode over the first light-emitting layer; the second light-emitting device includes a second pixel electrode, a second light-emitting layer over the second pixel electrode, and the common electrode over the second light-emitting layer; the first insulating layer covers a side surface and part of a top surface of the first light-emitting layer and a side surface and part of a top surface of the second light-emitting layer; the second insulating layer overlaps with the side surface and the part of the top surface of the first light-emitting layer and the side surface and the part of the top surface of the second light-emitting layer with the first insulating layer therebetween; the common electrode covers the second insulating layer; in a cross-sectional view, an end portion of the second insulating layer has a tapered shape with a taper angle less than 90°; and the second insulating layer covers at least part of a side surface of the first insulating layer.