OLED Pixel Define Layer Roughening for Crosstalk Reduction
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Solution Overview
Problem
Current OLED devices with a common hole injection layer (HIL) face issues with directional carrier transmission due to voltage differences between color units, leading to unwanted activation of adjacent color sub-pixel units, especially at low gray scales, causing crosstalk and difficulty in controlling single color points.
Innovation Solution
A method involving a substrate with a first electrode layer and a pixel define layer, where a roughening process is performed on the upper surface of the pixel define layer to form a rough surface, resulting in a first functional layer with reduced carrier-transporting capability in the extending direction, which is used to cover the exposed electrode layer, thereby reducing crosstalk and interference during the formation of the functional stack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a common hole injection layer (HIL) is used for RGB light emitting units, then the process flow is simplified and manufacturing cost is reduced, but directional transmission of carriers occurs due to voltage differences between different color devices, causing crosstalk and unwanted activation of adjacent color sub-pixel units
Solution Approach 1:
The patent applies local quality by creating a rough surface specifically on the pixel define layer in the non-light-emitting region, while keeping the light-emitting region smooth. This localized surface modification creates a barrier that selectively blocks carrier diffusion from non-light-emitting regions to light-emitting regions, preventing crosstalk without affecting the normal operation of the light-emitting areas. The rough surface structure is formed only where needed to stop carrier directional transmission caused by voltage differences between different color units.
2Ease of operation
If the turn-on voltage of a unit device is applied, then the desired color sub-pixel unit is activated, but carriers directionally transmit through the HIL causing other color units to also turn on, especially at low gray scales
Solution Approach 1:
The patent introduces the rough surface structure as an intermediary barrier between the common HIL and the light-emitting regions. This rough surface acts as a mediator that interrupts the directional carrier transmission path through the HIL, preventing carriers from reaching adjacent color units when a specific color is activated. The rough surface structure with its increased tortuous path and reduced effective area serves as a physical intermediary that blocks carrier diffusion while allowing the desired color unit to activate normally.
3Object-affected harmful factors
If a roughening process is performed on the pixel define layer, then carrier-transporting capability in the extending direction is reduced, but additional manufacturing steps are required
Solution Approach 1:
The patent merges the roughening process with the existing pixel define layer formation step. The rough surface is created on the pixel define layer during the same manufacturing sequence where the pixel define layer is already being formed, rather than adding a completely separate roughening step. This integration combines the pixel define layer patterning and the surface roughening into a unified process sequence, reducing the overall number of discrete manufacturing steps while achieving the carrier blocking effect.
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
The method effectively reduces carrier transportability in the desired direction, minimizing crosstalk and lowering manufacturing costs by performing the surface process before the deposition of the functional layers, while maintaining the performance of the OLED device.
Implementation Method 1
performing a roughening process on at least a part of an upper surface, which is away from the first electrode layer, of the pixel define layer to form a rough surface
Data Source
AI summary
The present disclosure relates to a method of manufacturing an OLED device, an OLED device and a display panel. The method comprises: forming a first electrode layer over a substrate; forming a pixel define layer over the first electrode layer, the pixel define layer having a plurality of openings each corresponding to a light emitting region of each sub-pixel unit; performing a roughening process over a surface of the pixel define layer apart away from the first electrode layer; forming a hole injection layer covering the pixel define layer and the openings; and forming a hole transport layer, a light emitting layer, an electron transport layer and a second electrode layer in sequence over the hole injection layer at regions corresponding to the openings.