SiN Protective Layer Fluorine Doping for Organic EL Devices

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Solution Overview

Problem

Organic electroluminescent (EL) devices face a trade-off between optical properties and protective performance due to silicon nitride protective layers, which exhibit high light absorption but poor initial optical properties, limiting their ability to utilize high luminous efficiencies and maintaining performance under high temperature and humidity.

Innovation Solution

The use of laminated protective layers composed of silicon, nitrogen, hydrogen, and fluorine, with specific fluorine content ranges (0.01 to 1 atomic percent), and layers composed of silicon, oxygen, hydrogen, and fluorine, or silicon, nitrogen, and hydrogen, to enhance structural stability and optical properties while blocking moisture and oxygen intrusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a silicon nitride protective layer is formed by plasma CVD, then protective performance is improved, but initial optical properties deteriorate due to high light absorption

Engineering Contradiction:

Improveprotective performanceVSAvoidinitial optical properties

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The patent changes the compositional parameters of the protective layer by incorporating fluorine at specific concentrations (0.01 to 1 atomic percent) and adjusting the Si:N:H:F ratios. This parameter modification reduces light absorption while maintaining protective performance, resolving the contradiction between reliability and optical properties.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite protective layer combining silicon nitride with fluorine-containing compounds. This composite structure integrates the protective characteristics of silicon nitride with the optical benefits of fluorine, achieving both high protective performance and excellent initial optical properties.

Inventive Principle:

Principle #40Composite materials

2Reliability

If a silicon nitride protective layer is used, then protective performance is improved, but luminescence efficiency deteriorates due to poor initial optical properties

Engineering Contradiction:

Improveprotective performanceVSAvoidluminescence efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

By optimizing the fluorine content (0.01 to 1 atomic percent) and compositional ratios, the patent reduces optical absorption in the protective layer. This minimizes energy loss from light absorption, thereby improving luminescence efficiency while preserving protective performance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The fluorine-modified silicon nitride composite layer combines the protective function with reduced optical absorption, preventing energy loss and maintaining high luminescence efficiency of the organic EL device.

Inventive Principle:

Principle #40Composite materials

3Reliability

If protective layers are added to block moisture and oxygen, then reliability is improved, but device complexity increases due to laminated structure

Engineering Contradiction:

Improveprotection against moisture and oxygenVSAvoidlaminated protective layer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple protective functions (moisture blocking, oxygen blocking, optical protection) into a single fluorine-modified silicon nitride protective layer. This integration maintains high reliability while reducing device complexity compared to multiple separate protective layers.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The fluorine-containing silicon nitride protective layer performs multiple functions simultaneously: it provides barrier protection against moisture and oxygen, maintains excellent optical properties, and ensures long-term device stability. This multi-functionality reduces the need for additional separate protective layers.

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 solution maintains excellent luminescence properties and initial optical performance of organic EL devices under high temperature and humidity, reducing deterioration and image defects, and allows independent control of optical and protective characteristics.

Implementation Method 1

technologies regarding protective layers for blocking the intrusion of moisture and oxygen from the outside

Methodology Applied

Scientific EffectPhysical barrier: Physical Containment

Implementation Method 2

the silicon nitride protective layer just formed by plasma CVD as described in the patent document exhibits higher light absorption

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS8063555B2Organic electroluminescent device with SiN layer containing hydrogen and fluorine

Publication Date: 2011.11.22 CANON KK

AI summary

An organic EL device includes a substrate; a layered structure including a first electrode, an organic layer, and a second electrode disposed on the substrate in this order; and laminated protective layers surrounding at least the layered structure. The protective layers are composed of silicon, nitrogen, hydrogen, and fluorine. The fluorine content in the outermost protective layer is in the range of 0.01 to 1.0 atomic percent.