Electroluminescent Display Device Trench Bank Structure
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Solution Overview
Problem
Current electroluminescent display devices face limitations in reducing bezel width due to the need for a reliable bezel to prevent moisture permeation and defects in mass production, which restricts the slimming of non-active areas and affects cathode delamination processes.
Innovation Solution
The implementation of a trench in the bank of the non-active area to block moisture permeation paths and retreat the cathode end to the active area, along with the use of an inorganic layer and a step alleviation layer to facilitate smooth cathode delamination, reduces bezel width and enhances reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cathode is formed to cover the organic layer in the non-active area to prevent moisture permeation, then reliability is improved, but the bezel width cannot be reduced
Solution Approach 1:
The non-active area is divided into a first non-active area (adjacent to active area) and a second non-active area (outer region). The cathode is selectively formed only in the first non-active area, while the second non-active area remains without cathode. This segmentation allows the bezel width to be reduced by eliminating the cathode from the second non-active area, while still maintaining moisture permeation prevention in the critical first non-active area through the bank structure and adhesive layer.
2Length of stationary object
If the cathode is retreated to the active area to reduce bezel width, then bezel width is reduced, but moisture permeation protection is compromised
Solution Approach 1:
The bank structure serves as an intermediary barrier between the active area and the external environment. By forming the bank to extend into the non-active area and creating a trench that exposes the planarization layer, the bank acts as a physical barrier that prevents moisture permeation paths. This allows the cathode to be retreated to the active area while maintaining moisture protection through the bank's barrier function.
3Reliability
If the cathode is formed to cover the organic layer to prevent defects in mass production, then manufacturing reliability is improved, but the non-active area cannot be slimmed
Solution Approach 1:
Different regions of the non-active area are assigned different functions and structures. The first non-active area (adjacent to active area) maintains cathode coverage for defect prevention, while the second non-active area (outer region) eliminates the cathode to reduce the overall non-active area. This local differentiation allows the non-active area to be slimmed while preserving manufacturing reliability in the critical region near the active area.
Data Source
AI summary
An electroluminescent display device comprises a display panel including an active area and a non-active area; a planarization layer extending to the non-active area of the display panel; a bank on the planarization layer that extends to the non-active area and includes a trench that exposes the planarization layer of the non-active area; an organic layer on the bank and separated by the trench; a cathode on a first organic layer in the inner direction area of the trench; and an adhesive layer and an encapsulation substrate over the cathode, wherein the adhesive layer may be in contact with a second organic layer in the outer direction area of the trench, and reliability can be improved and a bezel width can be reduced.