Low-Work-Function Carbon Nanotube Needle Tip for Electron Emission

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Solution Overview

Problem

The existing carbon nanomaterial functionalized needle tips have high interface resistance and low mechanical strength, limiting their practical applications in electron emission sources due to the high work function of the carbon nanocone tip end.

Innovation Solution

A carbon nanomaterial functionalized needle tip is modified with a low work function material, such as metals, metal carbides, metal oxides, borides, nitrides, or endohedral metallofullerene, by forming a covalent bond between the carbon nanomaterial and the needle tip, and modifying the interior or outer surface of the carbon nanomaterial with these materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If carbon nanomaterial is used to functionalize the needle tip, then the mechanical strength and interface connection are improved, but the work function remains high which limits electron emission performance

Engineering Contradiction:

Improveinterface connection strengthVSAvoidelectron emission performance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent creates a composite structure by depositing low work function material (such as barium, strontium, or their oxides) onto the carbon nanomaterial functionalized needle tip. This composite combines the high mechanical strength and stable interface connection of carbon nanomaterial with the low work function property of the deposited material, thereby improving electron emission performance while maintaining structural integrity.

Inventive Principle:

Principle #40Composite materials

2Reliability

If low work function material is deposited on the needle tip, then the electron emission performance is improved, but the interface resistance and mechanical strength deteriorate

Engineering Contradiction:

Improveelectron emission performanceVSAvoidinterface connection strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent applies preliminary action by first functionalizing the needle tip with carbon nanomaterial to create a strong mechanical foundation and stable interface connection. Only after this preliminary structural preparation is complete is the low work function material deposited. This sequence ensures that the interface has adequate mechanical strength before the emission-critical material is added.

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If conventional physical adsorption is used to adhere nanomaterials to the needle tip, then the preparation process is simple, but the interface resistance is high and mechanical strength is low

Engineering Contradiction:

Improvepreparation process simplicityVSAvoidinterface connection strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent replaces the mechanical physical adsorption system with a chemical bonding system. By using plasma treatment or chemical vapor deposition, carbon nanomaterials form covalent bonds with the needle tip substrate, creating a chemically bonded interface that provides both low interface resistance and high mechanical strength, overcoming the limitations of simple physical adsorption.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 modified carbon nanomaterial functionalized needle tip achieves a lower electron emission barrier, reducing the electric field intensity required for electron emission, and improving the emission current and efficiency while maintaining a stable and mechanically strong structure.

Implementation Method 1

combining a carbon nanomaterial with a material of a needle tip by means of a covalent bond

Methodology Applied

Scientific EffectCovalent bonding: Chemical Bonding

Implementation Method 2

modifying the interior or outer surface of the carbon nanomaterial with a low work function material

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Data Source

PatentUS12313653B2Carbon nanomaterial functionalized needle tip modified with low work function material and preparation method thereof

Publication Date: 2025.05.27 THE NAT CENT FOR NANOSCI & TECH NCNST OF CHINA

AI summary

A carbon nanomaterial functionalized needle tip is modified with a low work function material. The needle tip is formed by combining a carbon nanomaterial with a material of a needle tip through a covalent bond. The interior or outer surface of the carbon nanomaterial is modified with a low work function material. The material of the needle tip is a metal which can be any of tungsten, iron, cobalt, nickel, and titanium. The carbon nanomaterial can be carbon nanocone or carbon nanotube. The tip of the carbon nanomaterial has the same orientation as the metal needle tip. The low work function material can be selected from metals, metal carbides, metal oxides, borides, nitrides, and endohedral metallofullerene. The carbon nanomaterial functionalized needle tip has a lower electron emission barrier, and can effectively reduce the electric field intensity required for electron emission, and improve the emission current and emission efficiency.