Hole Injection Layer Alkali Resistance via Crosslinked Polymer

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The alkaline developing solution deteriorates PEDOT/PSS in the hole injection layer of display devices, leading to a decrease in hole injection efficiency and luminous efficiency of the display device.

Innovation Solution

Incorporating a crosslinked polymer adjacent to the PEDOT/PSS in the hole injection layer, which is insoluble in alkaline solutions, to protect the PEDOT/PSS from deterioration, and using an aqueous solution containing PEDOT/PSS and a water-soluble photoresist for layer formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If an alkaline developing solution is used for patterning the light-emitting layer, then the patterning process can be completed, but the PEDOT/PSS in the hole injection layer deteriorates

Engineering Contradiction:

Improvepatterning processVSAvoidhole injection efficiency

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

A protective layer comprising a polymer is introduced as an intermediary between the alkaline developing solution and the PEDOT/PSS. This protective layer allows the alkaline developing solution to perform patterning while preventing direct contact with and deterioration of the PEDOT/PSS, thus resolving the contradiction between manufacturing ease and device reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The polymer protective layer acts as a sacrificial or temporary protective element that can be applied, used during the patterning process to protect PEDOT/PSS, and then removed or degraded. This disposable protective mechanism enables the use of alkaline developing solutions without permanently compromising the hole injection layer

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If PEDOT/PSS is used in the hole injection layer, then good hole injection performance is achieved, but the layer becomes sensitive to alkaline solutions

Engineering Contradiction:

Improvehole injection efficiencyVSAvoidalkali resistance

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The hole injection layer is designed as a composite structure combining PEDOT/PSS with a polymer protective layer. This composite material approach maintains the excellent hole injection properties of PEDOT/PSS while adding alkali resistance through the polymer component, thus resolving the contradiction between injection performance and chemical stability

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The protective polymer is applied locally adjacent to or over the PEDOT/PSS regions that require protection from alkaline solutions. This localized protection strategy maintains the functional properties of PEDOT/PSS where needed while providing alkali resistance only in the specific areas exposed to the developing solution

Inventive Principle:

Principle #3Local quality

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 configuration enhances the alkali resistance of the hole injection layer, reducing PEDOT/PSS deterioration and improving the luminous efficiency of the display device.

Implementation Method 1

a water-soluble photoresist adjacent to a mixture (PEDOT/PSS) in which polystyrene sulfonic acid (PSS) is mixed with polyethylenedioxythiophene (PEDOT)

Methodology Applied

Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentUS20240260302A1Display device, method for producing display device, and aqueous solution

Publication Date: 2024.08.01 SHARP DISPLAY TECHNOLOGY CORP

AI summary

A hole injection layer included in a display device according to the disclosure contains a mixture (PEDOT/PSS) obtained by mixing polystyrene sulfonic acid (PSS) with polyethylenedioxythiophene (PEDOT), and a polymer adjacent to the PEDOT/PSS.