Display Pixel Electrode Stacks for Maskless Emitter Separation
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Solution Overview
Problem
Display devices with high pixel integration face challenges in forming light emitting elements separated from each other without a mask process, particularly in small sizes, and are vulnerable to moisture permeation.
Innovation Solution
A display device structure is fabricated with a pixel electrode configuration that includes a lower transparent electrode layer, a metal electrode layer, and an upper transparent electrode layer, with a side surface alignment or protrusion to prevent moisture permeation, and a method involving etching processes using different etchants to form light emitting elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If display device is implemented in very small size with high pixel integration degree, then pixel density is improved, but emission area is reduced making it difficult to form separated light emitting elements through mask process
Solution Approach 1:
The pixel electrode is segmented into multiple emission areas separated by insulating patterns, allowing each emission area to be independently defined and filled with light emitting materials without requiring complex mask processes. This segmentation enables precise control of light emitting element positions even at high pixel densities.
Solution Approach 2:
The patent utilizes vertical dimension (thickness direction) to define emission areas through insulating patterns with different heights, creating a three-dimensional structure that enables separation of light emitting elements without compromising horizontal pixel density. The banks and insulating patterns create vertical barriers that prevent lateral diffusion while maintaining compact horizontal dimensions.
2Ease of manufacture
If conventional pixel electrode structure is used, then manufacturing is simpler, but moisture permeation occurs causing display defects
Solution Approach 1:
The patent employs thin film encapsulation structures including inorganic pixel defining layers, insulating patterns, and sealing layers that form protective barriers against moisture permeation. These thin film structures conform to the pixel electrode geometry while providing effective moisture blocking, preventing mura defects without complicating the manufacturing process excessively.
Solution Approach 2:
The pixel electrode structure is segmented with insulating patterns and banks that create isolated compartments, preventing moisture diffusion across the entire display. This segmentation ensures that moisture permeation is blocked at multiple interfaces, enhancing overall reliability while maintaining manufacturing feasibility through standard deposition and etching processes.
3Manufacturing precision
If mask process is used to form separated light emitting elements, then separation precision is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts and removes mask processes from the manufacturing sequence by using self-aligned insulating patterns and banks that define emission areas through deposition and etching of conductive and insulating materials. This extraction eliminates the need for separate masking steps while achieving comparable or superior separation precision through material-selective etching and vertical structure definition.
Solution Approach 2:
The insulating patterns and banks serve dual functions: they define the geometric boundaries of emission areas and simultaneously act as barriers to prevent lateral diffusion of light emitting materials. This self-service approach eliminates the need for separate mask processes, reducing manufacturing complexity while maintaining high separation precision through the inherent properties of the deposited structures.
Data Source
AI summary
A display device includes a pixel electrode including a lower transparent electrode layer disposed on a substrate, a metal electrode layer disposed on the lower transparent electrode layer, and an upper transparent electrode layer disposed on the metal electrode layer; an inorganic pixel defining layer disposed on the substrate and exposing the pixel electrode; a light emitting layer disposed on the pixel electrode; a common electrode disposed on the light emitting layer; a first bank disposed on the inorganic pixel defining layer; and a second bank disposed on the first bank and having a side surface protruding more than a side surface of the first bank. A side surface of the lower transparent electrode layer is aligned with a side surface of the metal electrode layer or protrudes more than the side surface of the metal electrode layer.