OLED Pixel Defining Units for Inkjet Printing Uniformity
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Solution Overview
Problem
Existing OLED display technologies face challenges in achieving uniform film thickness and preventing color mixing due to material utilization inefficiencies and substrate bending issues during manufacturing, particularly with evaporation processes and inkjet printing techniques.
Innovation Solution
The OLED display incorporates a substrate base with a switch array layer, a conductive layer of anode electrodes, and pixel defining units with specific structural features such as grooves and openings to control the flow and placement of inkjet printing ink, ensuring uniformity and preventing ink from spreading to incorrect regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If inkjet printing technology is used to manufacture OLED panels, then material utilization rate is improved and production of large panels is simplified, but film thickness uniformity deteriorates and color mixing occurs
Solution Approach 1:
The pixel defining layer is divided into multiple portions (first portion, second portion, third portion) with different structures. Each portion serves a specific function: the first portion defines pixel boundaries, the second portion creates light-emitting regions on anode electrodes, and the third portion provides ink collection grooves. This segmentation allows precise control of inkjet printing ink distribution while maintaining material utilization benefits.
Solution Approach 2:
Different regions of the pixel defining layer are given different properties. The second portion has openings with specific contact angles to control ink spreading, while the third portion has grooves to collect excess ink. This local differentiation ensures uniform film thickness in light-emitting regions while preventing color mixing in non-light-emitting regions.
2Device complexity
If inkjet printing technology is used to manufacture OLED panels, then production process complexity is reduced and large panel production is enabled, but color mixing between adjacent light-emitting regions occurs
Solution Approach 1:
The pixel defining layer incorporates a third portion with grooves specifically designed to collect excess inkjet printing ink. This local structural modification prevents ink from spreading into adjacent light-emitting regions, thereby preventing color mixing while maintaining the simplicity of the inkjet printing process.
Solution Approach 2:
The third portion of the pixel defining layer acts as an intermediary structure between adjacent pixels. The grooves in this portion capture and contain excess ink, serving as a barrier that prevents ink from migrating to neighboring light-emitting regions, thus preventing color mixing.
3Manufacturing precision
If evaporation processes are used to manufacture OLED panels, then film deposition is achieved, but material utilization rate deteriorates and substrate bending causes non-uniform film thickness
Solution Approach 1:
The pixel defining layer with its specific structure (including grooves and openings) is prepared in advance before inkjet printing. This preliminary structure guides the inkjet printing process, ensuring that material is deposited only where needed and excess material is collected, thereby improving material utilization rate while maintaining film thickness uniformity.
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
This solution enhances film thickness uniformity and prevents color mixing by directing excess ink into grooves, thereby improving material utilization and reducing production costs and complexity.
Implementation Method 1
a groove is defined at the first portion, at least one opening is defined at the second portion; wherein a width of the opening is less than a width of the second portion
Implementation Method 2
The inkjet printing technology is dissolving an OLED material in a solvent or dispersing the OLED material as nanometer droplets in a solvent, and then spraying the material onto a substrate surface through a nozzle and forming a film through a drying process
Implementation Method 3
a polarity of the material of the second sub layer is opposite to that of the light-emitting layer inkjet printing ink, a contact angle between the light-emitting layer inkjet printing ink and the second sub layer is greater than 45 degrees; a polarity of the material of the first sub layer is the same as that of the light-emitting layer inkjet printing ink, a contact angle between the light-emitting layer inkjet printing ink and the first sub layer ranges from 10 degrees to 45 degrees
Data Source
AI summary
The present application provides an organic light-emitting diode display. The display includes a plurality of pixel defining units, the pixel defining unit includes a first portion formed on a switch array layer which is not covered by anode electrodes and a second portion formed on the anode electrode, a groove is defined at the first portion, and at least one opening is defined at the second portion; an organic light-emitting layer including a plurality of organic light-emitting units, the organic light-emitting layer is formed on the anode electrodes which are not covered by the second portion.