Surface Processing Layer Grooves for OLED Pixel Boundary Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In organic light-emitting display devices, the hole transport layer can inadvertently spread to adjacent pixels due to ejection pressure and speed, causing unwanted mixing of light colors and degrading display quality.
Innovation Solution
A surface processing layer with grooves is used to prevent the charge transport layer from spreading to adjacent pixels, featuring a design where the grooves increase in width towards adjacent pixels and have a lattice or oblique shape to contain the layer within the pixel boundaries, ensuring uniform formation and preventing color overlap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the hole transport layer solution is ejected onto the surface processing layer with high ejection pressure and speed, then the formation efficiency is improved, but the solution spreads errantly toward adjacent pixels causing color mixing
Solution Approach 1:
The surface processing layer is segmented into multiple regions with different wettability characteristics. The pixel region has high wettability to the hole transport layer solution, while the adjacent pixel region has low wettability. This segmentation allows the solution to be ejected with high pressure for efficiency while the low wettability region acts as a barrier to prevent spreading into adjacent pixels, thus maintaining precision.
Solution Approach 2:
Different regions of the surface processing layer are given different local properties: the pixel region is made lyophilic (high wettability) to the hole transport layer solution to ensure good adhesion and uniform formation, while the adjacent pixel region is made lyophobic (low wettability) to prevent solution spreading. This local quality differentiation resolves the contradiction between formation efficiency and pixel boundary precision.
2Area of stationary object
If the hole transport layer is formed to cover the entire pixel area including edges, then the coverage is improved, but the layer spreads into adjacent pixels causing color overlap
Solution Approach 1:
The surface processing layer acts as an intermediary between the pixel region and adjacent pixel region. It provides a transition zone with controlled wettability that allows the hole transport layer to be formed with adequate coverage within the pixel while simultaneously preventing the layer from spreading into adjacent pixels. The intermediary region with low wettability to the hole transport layer solution serves as a protective barrier.
Solution Approach 2:
The potential harm of solution spreading is converted into a benefit by designing the surface processing layer with spatially varying wettability. The same surface processing layer that enables good adhesion within the pixel (through high wettability) also prevents unwanted spreading (through low wettability in adjacent regions). The potential problem of over-spreading is transformed into a controlled feature that defines pixel boundaries.
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 effectively confines the charge transport layer and light-emitting layer within pixel boundaries, preventing color mixing and enhancing display quality by maintaining the integrity of distinct color emissions in adjacent pixels.
Implementation Method 1
A light-emitting display device may include a surface processing layer having roughness formed on an edge thereof by a plurality of grooves. The surface processing layer may prevent a first charge transport layer solution ejected onto the surface processing layer using an inkjet print method or a nozzle print method from spreading beyond the surface processing layer.
Implementation Method 2
The grooves may prevent the first charge transport layer solution from spreading toward an adjacent pixel
Implementation Method 3
a first charge transport layer solution ejected onto the surface processing layer using an inkjet print method or a nozzle print method
Implementation Method 4
The operation of forming the charge transport layer may include providing a charge transport layer solution into the opening of the pixel defining layer and drying the charge transport layer solution, and the operation of forming the light-emitting layer may include providing a light-emitting layer solution into the opening of the pixel defining layer and drying the light-emitting layer solution.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A light-emitting display device includes a substrate (105) having a plurality of pixels (PX). A first electrode (110) is provided on the substrate (105) for each pixel, and a pixel defining layer (120) defines each of the pixels (PX). The pixel defining layer (120) has an opening to expose the first electrode (110). A charge injection layer (130) is on the first electrode (110), and a surface processing layer (140) is on the charge injection layer (130). The surface processing layer (140) extends from inside the opening of the pixel defining layer (120) to a top surface of the pixel defining layer (120). The surface processing layer (140) including a plurality of grooves in a portion extending on the top surface of the pixel defining layer (120). A charge transport layer (150) is on the surface processing layer (140), a light-emitting layer (160) is on the charge transport layer (150), and a second electrode (190) is on the light-emitting layer (160).