OLED Pixel Definition Layer Aperture Design
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Solution Overview
Problem
In OLED devices, the differing decay rates of red, green, and blue light materials lead to color cast issues due to ink overflow between pixel units during the solution-based preparation of organic luminescent layers, particularly with red pixel units having small aperture ratios and thick film thicknesses, causing cross-color problems.
Innovation Solution
A pixel definition layer with openings of varying dimensions and shapes for different pixel units, where the first opening has a smaller bottom surface aperture and larger extension space for slow-decaying red luminescent materials, and the second opening has a larger bottom surface aperture and smaller extension space for fast-decaying blue materials, maintaining consistent aperture ratios and preventing ink overflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the bottom surface aperture of the first opening is made smaller to maintain consistent aperture ratios, then the ink overflow problem is reduced, but the internal volume of the opening becomes insufficient to accommodate the thick film of red luminescent material
Solution Approach 1:
The opening structure transitions from a simple cylindrical shape to a multi-dimensional structure with an extension space protruding from the side wall. This dimensional change allows the opening to accommodate more ink volume without increasing the bottom surface aperture area, thus preventing ink overflow while providing sufficient space for the thick red luminescent material film.
Solution Approach 2:
The extension space is nested within the opening structure, creating an additional internal chamber that increases the total volume available for ink accommodation. This nested design effectively adds storage capacity without expanding the footprint or bottom aperture of the opening.
2Stability of the object's composition
If the aperture ratio is kept consistent across different pixel units, then the display uniformity is improved, but the ink overflow problem persists for pixel units with slow-decaying luminescent materials
Solution Approach 1:
While maintaining consistent aperture ratios at the opening level, the invention introduces local quality variations through the extension space. Different pixel units have differently sized extension spaces according to their specific needs - red pixel units with slow-decaying materials have larger extension spaces, while blue pixel units with fast-decaying materials have smaller or no extension spaces. This localized differentiation solves the ink overflow problem for specific pixel types without compromising overall display uniformity.
3Illumination intensity
If the film thickness is increased for red pixel units to achieve desired luminosity, then the light output is improved, but the ink overflow problem is exacerbated
Solution Approach 1:
The opening volume is segmented into two distinct spaces: the main opening volume and the extension space. This segmentation allows the main opening to maintain a consistent aperture ratio for uniformity, while the separate extension space provides additional volume specifically for accommodating the increased film thickness of red pixel units, preventing ink overflow while supporting higher light output.
Data Source
AI summary
A pixel definition layer and an OLED device are provided. The pixel definition layer includes a plurality of openings, the openings each being provided with bottom surface opening, a top surface opening and a side wall. The openings at least include a first opening defining a first pixel unit and a second opening defining a second pixel unit. The first opening is filled with a first pixel luminescent material, and the second opening is filled with a second pixel luminescent material. A decay rate of the first pixel luminescent material is lower than that of the second pixel luminescent material. The area of the bottom surface opening of the first opening is smaller than that of the bottom surface opening of the second opening. The side wall of the opening is provided with a pre-set reference surface. The pixel definition layer can be used for preparing an OLED device.