Carbon-Based Thermoelectric Conversion Element for Cost Reduction

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Solution Overview

Problem

The existing spin current to charge current conversion materials for thermoelectric conversion elements, such as Pt and Pd, are expensive, necessitating the search for cheaper alternatives that can maintain high spin-Hall angles and conversion efficiencies.

Innovation Solution

A thermoelectric conversion element featuring a magnetic layer with in-plane magnetization and an electromotive layer made of carbon with anisotropic electric conductivity, incorporating an additive to enhance the spin-Hall effect and conversion efficiency, utilizing materials like graphite intercalation compounds or carbon nanotubes to achieve a lower manufacturing cost and improved performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If expensive materials like Pt or Pd are used as electromotive layers, then high spin-Hall angle and conversion efficiency are achieved, but manufacturing cost increases

Engineering Contradiction:

Improveconversion efficiencyVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces expensive Pt or Pd electromotive layers with cheaper carbon-based materials (graphite, carbon nanotubes, amorphous carbon) that can achieve comparable spin-Hall angles. This substitution directly addresses the cost issue while maintaining the required conversion efficiency through careful material selection and interface engineering with magnetic layers

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent employs composite structures combining carbon-based electromotive layers with magnetic layers (such as CoFeB, CoFe, or permalloy). The composite interface between carbon and magnetic materials enables efficient spin current generation through the spin-Seebeck effect, while the carbon layer provides cost-effective spin-Hall effect for converting spin current to charge current

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If carbon-based materials are used as electromotive layers, then manufacturing cost decreases, but spin-Hall angle and conversion efficiency may be reduced

Engineering Contradiction:

Improvemanufacturing costVSAvoidspin-Hall angle

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent optimizes various parameters of carbon-based electromotive layers including crystallinity (using graphite or carbon nanotubes instead of amorphous carbon), layer thickness (controlling to appropriate ranges), and interface quality with magnetic layers. These parameter optimizations enable carbon materials to achieve spin-Hall angles comparable to Pt or Pd

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces intermediate layers or interface engineering between carbon electromotive layers and magnetic layers to enhance spin current injection efficiency. The interface structure acts as an intermediary that facilitates efficient spin-charge conversion, compensating for any inherent deficiencies in carbon material performance

Inventive Principle:

Principle #24Intermediary (Mediator)

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 use of carbon-based electromotive layers with additives results in a more cost-effective spin current to charge current conversion, achieving a high spin-Hall angle and enhanced conversion efficiency comparable to expensive materials like Pt, while reducing production costs.

Implementation Method 1

The spin-Seebeck effect is a phenomenon that when a temperature gradient is applied to a magnetic material, spin current is induced in a direction parallel to the temperature gradient

Methodology Applied

Scientific EffectSpin-Seebeck effect:

Implementation Method 2

As a phenomenon opposite thereto, it is known that when spin current flows, electromotive force is generated. This is called the 'inverse spin-Hall effect'

Methodology Applied

Scientific EffectInverse spin-Hall effect:

Data Source

PatentUS9608095B2Thermoelectric conversion element and manufacturing method for the same

Publication Date: 2017.03.28 NEC CORP

AI summary

Concerning a thermoelectric conversion element, it is desired to provide a new spin current to charge current conversion material. A thermoelectric conversion element includes a magnetic layer possessing in-plane magnetization, and an electromotive layer magnetically coupled to the magnetic layer. The electromotive layer is formed of a carbon material, possesses anisotropy of electric conductivity, and further includes an additive.