Photosensitive Siloxane Resin for OLED Pixel Definition Layers

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Solution Overview

Problem

Existing display technologies face challenges with insulating layers in liquid crystal and organic light emitting displays, particularly in achieving high sensitivity, resolution, adherence, transmittance, and heat resisting discoloration properties while minimizing outgassing and moisture absorptivity.

Innovation Solution

A positive photosensitive siloxane resin composition is developed, comprising a siloxane copolymer obtained through hydrolysis and condensation polymerization of reactive silanes, combined with a 1,2-quinonediazide compound and a solvent, which includes a ladder structure and has a thermal decomposition temperature of 450°C or more, and is used to form a pixel definition layer in organic light emitting displays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If conventional insulating materials are used for wire insulation in displays, then ease of manufacture is maintained, but heat resistance is insufficient and outgassing occurs

Engineering Contradiction:
Improveheat resistanceVSAvoidoutgassing suppression
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The patent uses a composite material system consisting of siloxane copolymer backbone with aromatic ring-containing side chains. This composite structure combines the thermal stability of siloxane bonds with the thermal resistance enhancement from aromatic rings, achieving both high heat resistance and low outgassing without compromising manufacturing processability

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent modifies the chemical structure parameters of the insulating material by introducing aromatic rings at specific positions in the siloxane chain and controlling the molecular weight and crosslinking density. These parameter changes enhance thermal stability and reduce outgassing while maintaining compatibility with existing display manufacturing processes

Inventive Principle:
Principle #35Parameter changes

2Temperature

If insulation materials with high heat resistance are used, then thermal stability is improved, but moisture absorptivity increases

Engineering Contradiction:
Improvethermal stabilityVSAvoidmoisture absorptivity
Core Design Contradiction:
TemperatureVSLoss of substance

Solution Approach 1:

The patent applies local quality modification by introducing hydrophobic aromatic ring structures at specific locations along the siloxane chain. These localized aromatic segments create hydrophobic zones that repel moisture while the overall siloxane structure maintains thermal stability, achieving both thermal resistance and low moisture absorptivity

Inventive Principle:
Principle #3Local quality

3Manufacturing precision

If advanced photosensitive resin composition is used, then sensitivity and resolution are improved, but adherence and heat resisting discoloration properties are enhanced

Engineering Contradiction:
ImproveresolutionVSAvoidadherence
Core Design Contradiction:
Manufacturing precisionVSStrength

Solution Approach 1:

The patent designs a multi-functional siloxane copolymer that simultaneously provides photosensitivity for high-resolution patterning, adhesion promotion through specific functional groups, and heat resistance through aromatic ring structures. This universal material performs multiple functions that were previously required from separate materials, achieving resolution, adherence, and heat resistance together

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 composition exhibits excellent sensitivity, resolution, adherence, and heat resisting discoloration properties, suppresses outgassing, and maintains low moisture absorptivity, thereby enhancing the reliability of display devices.

Implementation Method 1

a siloxane copolymer obtained by performing hydrolysis and condensation polymerization

Methodology Applied
Scientific EffectHydrolysis: Hydrolysis

Implementation Method 2

hydrolysis and condensation polymerization of i) at least one reactive silane and ii) at least one 4-functional reactive silane

Methodology Applied
Scientific EffectCondensation polymerization: Chemical Bonding

Implementation Method 3

a positive photosensitive siloxane resin composition including a siloxane copolymer and a 1,2-quinonediazide compound

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentEP3040370B1Positive photosensitive siloxane resin composition and display device formed using the same
Publication Date: 2019.02.06 SAMSUNG DISPLAY CO LTD
  • EP3040370B1 patent drawingFigure 1
  • EP3040370B1 patent drawingFigure 2
  • EP3040370B1 patent drawingFigure 3

AI summary

A positive photosensitive siloxane resin composition includes a) a siloxane copolymer obtained by performing hydrolysis and condensation polymerization of i) at least one reactive silane represented by the following Chemical Formula 1 and ii) at least one 4-functional reactive silane represented by the following Chemical Formula 2 under a catalyst, the copolymer having a polystyrene-converted weight average molecular weight Mw of 1,000 to 20,000,          (R1)nSi(R2)4-n     [Chemical Formula 1]          Si(R3)4     [Chemical Formula 2] wherein R1s may each independently be any one of an alkyl group having 1 to 10 carbon atoms and an aryl group having 6 to 15 carbon atoms, R2 may be an alkoxy group having 1 to 4 carbon atoms, phenoxy, or acetoxy, R3s may each independently be any one of an alkoxy group having 1 to 4 carbon atoms, phenoxy, or an acetoxy group, and n may be a natural number of 1 to 3, b) a 1,2-quinonediazide compound, and c) a solvent.