Silver Nanoparticle Electrode Composition for Low-Temperature Solar Cells

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Solution Overview

Problem

Conventional methods for manufacturing solar cell electrodes face challenges in maintaining high electric conductivity and reflectance over time due to the degradation of organic materials used in low-temperature sintering processes, and they often require high-temperature baking that can damage substrate materials.

Innovation Solution

A composition of metal nanoparticles, primarily silver, with a primary grain size of 10 to 50 nm, chemically modified by a protective agent with a carbon backbone of 1 to 3 carbon atoms, dispersed in a medium, allowing for low-temperature baking (130 to 400°C) without organic material residue, and optionally including additives like metal oxides or silicone oils for enhanced adhesion and texture control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by stationary object

If low-temperature sintering (100 to 250°C) is used to manufacture solar cell electrodes, then energy consumption is reduced and substrate damage is avoided, but organic material degrades over time causing loss of electric conductivity and reflectance

Engineering Contradiction:
Improvebaking temperatureVSAvoidelectric conductivity stability
Core Design Contradiction:
Use of energy by stationary objectVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the organic vehicle from conventional high-molecular-weight resins to low-molecular-weight carboxylic acids (formic acid, acetic acid, propionic acid) with specific molecular weights. This parameter change enables complete decomposition and volatilization at low sintering temperatures (100-250°C), eliminating carbon residue that would otherwise degrade over time and maintain electrode reliability without requiring high temperatures.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs low-molecular-weight organic vehicles that are intentionally designed to be temporary and completely decomposable during sintering. These short-living organic materials serve only as transient binding agents during the coating process and completely volatilize during low-temperature sintering, leaving no persistent carbon residue that would cause long-term degradation of electrode properties.

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

2Temperature

If conventional organic vehicles are used in low-temperature sintering, then substrate damage is avoided, but carbon residue forms causing deterioration of electrode properties over time

Engineering Contradiction:
Improvebaking temperatureVSAvoidcarbon residue
Core Design Contradiction:
TemperatureVSObject-generated harmful factors

Solution Approach 1:

The patent fundamentally changes the molecular weight parameter of the organic vehicle from conventional high-molecular-weight resins (polymers) to low-molecular-weight carboxylic acids (1-3 carbon atoms). This parameter change transforms the thermal behavior during sintering: the low-molecular-weight compounds completely decompose and volatilize at 100-250°C without forming persistent carbon residue, thereby eliminating the harmful effect while maintaining low processing temperature.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent converts the potential harm of organic material degradation into a benefit by selecting low-molecular-weight carboxylic acids that completely volatilize without forming carbon residue. The organic vehicle's decomposition, which would normally be harmful, is transformed into a beneficial complete removal process that leaves no carbon residue to cause long-term electrode deterioration.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Object-generated harmful factors

If high-temperature baking is used to remove organic material completely, then carbon residue is eliminated, but substrate materials with low heatproof temperature are damaged

Engineering Contradiction:
Improvecarbon residueVSAvoidsubstrate damage
Core Design Contradiction:
Object-generated harmful factorsVSObject-affected harmful factors

Solution Approach 1:

The patent changes the organic vehicle's molecular weight and chemical structure parameters to enable complete decomposition and volatilization at low temperatures (100-250°C). This parameter change allows the organic material to be completely removed without carbon residue formation while keeping the baking temperature below the heatproof temperature limit of the substrate, thereby eliminating both carbon residue and substrate damage simultaneously.

Inventive Principle:
Principle #35Parameter changes

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 results in electrodes with sustained high electric conductivity and reflectance, improved adhesion, and reduced production costs due to lower processing temperatures, suitable for various substrate materials including those with low heatproof temperatures.

Implementation Method 1

metal nanoparticles are dispersed in a dispersive medium

Methodology Applied
Scientific EffectDispersion: Dispersion (of waves)

Implementation Method 2

baking the base material having the film formed on an upper surface at 130 to 400° C.

Methodology Applied
Scientific EffectSintering: Sintering

Implementation Method 3

without organic material residue

Methodology Applied
Scientific EffectEvaporation: Evaporation

Data Source

PatentUS9312404B2Composition for manufacturing electrode of solar cell, method of manufacturing same electrode, and solar cell using electrode obtained by same method
Publication Date: 2016.04.12 MITSUBISHI MATERIALS CORP

AI summary

A composition for manufacturing an electrode of a solar cell, comprising metal nanoparticles dispersed in a dispersive medium, wherein the metal nanoparticles contain silver nanoparticles of 75 weight % or more, the metal nanoparticles are chemically modified by a protective agent having a main chain of organic molecule comprising a carbon backbone of carbon number of 1 to 3, and the metal nanoparticles contains 70% or more in number-average of metal nanoparticles having a primary grain size within a range of 10 to 50 nm.