Planarizing Film for Display Device Moisture and Unevenness
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Solution Overview
Problem
The reliability of thin lightweight displays using light-emitting elements is compromised by moisture-induced deterioration and unevenness under the elements, leading to defects such as dark spots and luminance decrease, and existing countermeasures do not sufficiently address these issues without increasing processing steps.
Innovation Solution
A method for manufacturing a display device that includes a thin film transistor and a light-emitting element with a planarizing film disposed between the electrodes, using a material with self-planarizing properties to relieve unevenness and prevent water penetration through an insulating film, without requiring additional processing steps or exposing the film to the external atmosphere.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a planarizing film is formed over the entire surface to relieve unevenness under the light-emitting element, then the unevenness is suppressed and manufacturing precision is improved, but the insulating film is exposed to external atmosphere and moisture permeability causes water penetration, worsening reliability
Solution Approach 1:
The planarizing film is selectively formed only in the pixel electrode formation region where unevenness needs to be suppressed, rather than covering the entire surface. This local application maintains surface flatness where needed while leaving other regions open for proper sealing and moisture protection
Solution Approach 2:
The planarizing film formation process is divided into selective regions: formed in the pixel electrode formation region to relieve unevenness, and not formed in the sealant formation region to allow proper sealing. This segmentation resolves the conflict between needing flatness and preventing moisture exposure
2Reliability
If the insulating film is removed by etching to prevent exposure to external atmosphere and water penetration, then reliability is improved, but additional processing steps and new masks are required, worsening device complexity and productivity
Solution Approach 1:
The planarizing film is selectively removed (taken out) from the sealant formation region while maintaining it in the pixel electrode formation region. This extraction eliminates the need for additional etching steps and masks to remove the film, as the selective formation process inherently creates the desired pattern
Solution Approach 2:
The selective planarizing film formation process serves multiple functions simultaneously: it relieves unevenness in the pixel electrode region, prevents water penetration by maintaining the film in sealed regions, and eliminates the need for additional removal processing steps
Data Source
AI summary
It is an object of the present invention to provide a method for manufacturing a display device in which unevenness generated under a light-emitting element does not impart an adverse effect on the light-emitting element. It is another object of the invention to provide a method for manufacturing a display device in which penetration of water into the inside of the display device through a film having high moisture permeability can be suppressed without increasing processing steps considerably. It is another object of the invention to provide a display device and a method for manufacturing a display device satisfying the above two simultaneously. A display device of the present invention to solve the above problems comprising a thin film transistor and a light-emitting element over an insulating surface formed on a substrate, wherein the light-emitting element includes a light-emitting laminated body interposed between a first electrode and a second electrode; wherein the first electrode is formed over an insulating film formed over the thin film transistor; and wherein a planarizing film is formed in response to the first electrode between the first electrode and the insulating film.