Core-shell indium-tin nanoparticles for transparent conductive films

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Solution Overview

Problem

Conventional methods for manufacturing transparent conductive films, such as sputtering and aerosol spray pyrolysis, face challenges including high costs, material inefficiency, and suboptimal physical properties like surface resistance and transmittance, particularly for large-scale production and thin film uniformity.

Innovation Solution

A core-shell structured nano particle composed of a indium core and a tin shell is synthesized using a non-vacuum method, where indium nano particles are formed through a reducing agent reaction and coated with a tin shell, allowing for improved material reactivity and sintering, and subsequently used to create a transparent conductive film via a coating and annealing process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If vacuum deposition methods (sputtering, MOCVD, ion plasma) are used to manufacture indium oxide transparent conductive films, then film quality and conductivity are improved, but manufacturing cost and device complexity increase

Engineering Contradiction:
Improvefilm qualityVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex vacuum deposition mechanical systems with a simple solution processing method. Instead of using sputtering equipment, MOCVD reactors, or ion plasma devices, the invention uses conventional coating equipment to apply a solution containing metal organic compounds, followed by simple thermal treatment. This substitution dramatically reduces device complexity while maintaining film quality through chemical vapor deposition mechanisms that occur during the thermal treatment step.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If sputtering method is used to control film thickness accurately, then manufacturing precision is improved, but productivity decreases due to time-consuming processes

Engineering Contradiction:
Improvefilm thickness controlVSAvoidmanufacturing efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent changes the fundamental parameters of the manufacturing process by transitioning from physical vapor deposition (sputtering) to chemical solution processing. Film thickness is controlled not by adjusting sputtering power and time, but by controlling the concentration of metal organic compounds in the solution and the coating conditions. The thermal treatment temperature and duration are also optimized parameters that control film formation. This parameter change enables faster processing while maintaining precise thickness control.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If aerosol spray pyrolysis method is used to produce transparent conductive films, then manufacturing cost is reduced, but film uniformity and transmittance deteriorate due to particle size control issues

Engineering Contradiction:
Improvemanufacturing costVSAvoidfilm uniformity
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent uses inexpensive metal organic compound solutions as disposable precursors instead of expensive vacuum deposition materials. The solution can be prepared at low cost using readily available chemicals, and the coating process uses simple, low-cost equipment. The metal organic compounds decompose completely during thermal treatment, leaving no residual organic material that would affect film uniformity or transmittance, thus achieving both low cost and high film quality.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 approach reduces manufacturing costs and improves material efficiency while achieving performance equivalent to conventional sputtering processes, with specific resistance and transmittance properties suitable for applications in solar cells and display devices.

Implementation Method 1

preparing a first solution comprising a reducing agent; preparing a second solution comprising indium (In) salt; dropwise adding the first solution to the second solution such that the first solution and the second solution are reacted with each other; composing an indium (In) nano particle through the reaction

Methodology Applied
Scientific EffectRedox reactions: Redox Reactions

Implementation Method 2

applying the coating liquid onto a substrate to form a coating layer

Methodology Applied
Scientific EffectDeposition: Deposition (physical)

Implementation Method 3

performing an annealing process on the coating layer

Methodology Applied
Scientific EffectAnnealing: Annealing

Implementation Method 4

performing an annealing process on the coating layer

Methodology Applied
Scientific EffectSintering: Sintering

Data Source

PatentEP3026011B1Core-shell nanoparticles for transparent electrically-conductive thin film formation, and production method for transparent electrically-conductive thin film using same
Publication Date: 2019.06.12 LG CHEM LTD

AI summary

Disclosed herein are a core-shell nano particle for formation of a transparent conductive film, a manufacturing method of the core-shell nano particle, and a manufacturing method of a transparent conductive film using the core-shell nano particle and, more particularly, a core-shell structured nano particle consisting of a core including indium or indium oxide and a shell including tin, a manufacturing method of the core-shell structured nano particle, and a manufacturing method of a transparent conductive film including (i) dispersing a core-shell structured nano particle into a solvent to manufacture a coating liquid, (ii) applying the coating liquid onto a substrate to form a coating layer, (iii) drying the coating layer, and (iv) performing an annealing process on the coating layer.