OLED Display Substrate Isolation Layer Design for Cathode Protection
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Solution Overview
Problem
Existing OLED display technologies face challenges in effectively isolating cathodes, leading to abnormal display and touch failures, especially when using sputter film plating processes, and are prone to cracks during substrate cutting, affecting display and touch performance.
Innovation Solution
A display substrate design featuring a base substrate with a pixel definition layer, an isolation layer comprising a first and second isolation portion with a specific obtuse angle slope and gap configuration, and an isolated layer with a first isolated portion covering the isolation layer, enhancing cathode isolation and preventing crack propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional isolation layer with inverted trapezoid structure is used, then the cathode isolation is attempted, but the isolation effect is poor because the side surface is covered with the cathode
Solution Approach 1:
The isolation layer is divided into two distinct parts: a first isolation portion with a first slope angle and a second isolation portion with a second slope angle. This segmentation allows each portion to serve different functions - the first portion provides initial isolation while the second portion with the steeper slope ensures complete coverage of the cathode side surface, eliminating the covering problem of conventional single-structure isolation layers.
Solution Approach 2:
Different portions of the isolation layer are given different slope angles to address local requirements. The first isolation portion uses a gentler slope angle for gradual transition, while the second isolation portion uses a steeper slope angle to ensure complete coverage of the cathode's side surface. This local differentiation of geometric properties solves the isolation effectiveness problem.
2Ease of manufacture
If sputter film plating process is used for cathode fabrication, then the cathode can be formed, but the diffusion effect causes worse isolation effect
Solution Approach 1:
The dual-portion isolation layer structure is designed in advance to counteract the diffusion effect of the sputter film plating process. By incorporating the second isolation portion with a steeper slope angle that extends further along the cathode side surface, the structure preemptively prevents the cathode material from diffusing into the isolation layer, thereby maintaining isolation effectiveness despite the inherent diffusion tendency of sputter-deposited cathodes.
3Ease of manufacture
If conventional isolation layer structure is used, then manufacturing is simpler, but cracks are easily generated during cutting and spread to display region
Solution Approach 1:
The isolation layer is segmented into two portions with different slope angles, which distributes stress more evenly throughout the structure. The first isolation portion with the gentler slope angle can accommodate stress from cutting operations, while the second isolation portion with the steeper slope angle provides reinforcement near the cathode interface, preventing crack propagation to the display region.
Solution Approach 2:
The first isolation portion with the gentler slope angle acts as a stress-absorbing buffer that is formed first, providing a cushioning effect against cracks during subsequent cutting operations. This preliminary structural element absorbs mechanical stress before it can propagate to the second isolation portion and the display region, thereby preventing crack-related failures.
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
The solution improves cathode isolation, preventing abnormal displays and touch failures, while also effectively preventing cracks from extending to the display region, thereby enhancing display quality and touch effect.
Implementation Method 1
a slope angle formed by at least one side edge and a bottom edge in a cross section of the second isolation portion is an obtuse angle in a direction perpendicular to the base substrate
Implementation Method 2
there is a gap between the first isolation portion and the second isolation portion at the obtuse angle
Data Source
AI summary
A display substrate includes a base substrate, a pixel definition layer, an isolation layer, and an isolated layer. The pixel definition layer includes pixel openings penetrating through the pixel definition layer. The isolation layer is not overlapping with the pixel openings. The isolation layer includes a first isolation portion and a second isolation portion. A slope angle formed by at least one side edge and a bottom edge in a cross section of the second isolation portion is an obtuse angle. There is a gap between the first isolation portion and the second isolation portion at the obtuse angle. The isolated layer includes a first isolated portion covering the isolation layer, and a second isolated portion and a third isolated portion on both sides of the first isolation portion respectively. The thickness of the first isolation portion is larger than the thickness of the isolated layer.