JPWO2010010783A1 - Thermoelectric conversion element - Google Patents

Thermoelectric conversion element Download PDF

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JPWO2010010783A1
JPWO2010010783A1 JP2010521654A JP2010521654A JPWO2010010783A1 JP WO2010010783 A1 JPWO2010010783 A1 JP WO2010010783A1 JP 2010521654 A JP2010521654 A JP 2010521654A JP 2010521654 A JP2010521654 A JP 2010521654A JP WO2010010783 A1 JPWO2010010783 A1 JP WO2010010783A1
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thermoelectric conversion
metal
conversion element
silver
semiconductor
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安藤 浩明
浩明 安藤
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Konica Minolta Inc
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    • HELECTRICITY
    • H10SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10NELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N10/00Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
    • H10N10/10Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects
    • H10N10/17Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects characterised by the structure or configuration of the cell or thermocouple forming the device

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Abstract

本発明は、応力によって生ずる不良を抑制することができ、可撓性(フレキシビリティ)に優れ、かつ高い熱電変換能力を有する熱電変換素子を提供する。この熱電変換素子は、熱電変換半導体及びアスペクト比が10以上で、太さが2nm以上、500nm以下の金属繊維の集合体が含有されていることを特徴とする。The present invention provides a thermoelectric conversion element that can suppress defects caused by stress, is excellent in flexibility, and has a high thermoelectric conversion capability. This thermoelectric conversion element includes a thermoelectric conversion semiconductor and an aggregate of metal fibers having an aspect ratio of 10 or more and a thickness of 2 nm or more and 500 nm or less.

Description

本発明は、ゼーベック効果等の熱電効果を用いた熱電変換素子に関するものである。   The present invention relates to a thermoelectric conversion element using a thermoelectric effect such as the Seebeck effect.

熱電変換材料、特に、室温付近で用いられるBi−Te系の熱電変換材料は非常に脆く、熱電変換素子にフレキシビリティを付与することが困難である。樹脂上に薄膜化した熱電変換素子を設ける方法や、電極に可撓性を有する材料を用いることで可撓性を付与する方法等の検討はなされてきたが、その効果は耐熱性の向上レベルに留まり、十分なフレキシビリティと熱電変換能を両立するには至っていないのが現状である。   Thermoelectric conversion materials, particularly Bi-Te based thermoelectric conversion materials used near room temperature, are very fragile, and it is difficult to impart flexibility to thermoelectric conversion elements. Although methods such as providing a thin thermoelectric conversion element on a resin and methods for imparting flexibility by using a flexible material for an electrode have been studied, the effect is the level of improvement in heat resistance. However, the current situation is that sufficient flexibility and thermoelectric conversion capacity are not achieved at the same time.

熱電変換素子自体を細いワイヤー状にして、高い熱電変換効率を得る試みがなされている(例えば、特許文献1〜3参照。)。これら提案されている方法によれば、Bi−Teなどの熱電変換半導体は、薄膜、ワイヤー状(以下、半導体ナノワイヤともいう)等の低次元構造とすることで、性能指数(ZT)を高くすることができると期待されると共に、フレキシビリティ化の期待もある。しかし、発電用途に用いる場合は大きな電流を取り出すことが必要であり、細線化あるいは構造の低次元化による内部抵抗の増大は、発電用途とは相容れないものである。   Attempts have been made to obtain high thermoelectric conversion efficiency by making the thermoelectric conversion element itself into a thin wire shape (see, for example, Patent Documents 1 to 3). According to these proposed methods, thermoelectric conversion semiconductors such as Bi-Te have a low dimensional structure such as a thin film or a wire (hereinafter also referred to as semiconductor nanowire), thereby increasing the figure of merit (ZT). It is expected that it will be possible, and there are also expectations for flexibility. However, when used in power generation applications, it is necessary to extract a large current, and an increase in internal resistance due to thinning or structure reduction is incompatible with power generation applications.

上記半導体ナノワイヤを束ねることは、高変換効率と大電流の取り出しとの両立を果たすことができる方法であると考えられているが、この場合は配向性を高めた緻密な構造をとる必要があり、高いフレキシビリティを得るには至らず、作製も困難を伴うものであった。   Bundling the semiconductor nanowires is considered to be a method that can achieve both high conversion efficiency and extraction of a large current. In this case, it is necessary to have a dense structure with improved orientation. However, high flexibility was not achieved, and production was also difficult.

一方、応力吸収構造を素子自体に設けるため、可撓性のカーボンナノチューブを基板に垂直に立て、高い熱伝導性と応力緩和の実現を図る方法も開示されている(例えば、特許文献4参照。)。しかしながら、この方法では異方性が強く、配向性を高くして接合する必要のあるカーボンナノチューブを用いたこのような素子においては、作製することが容易でない。また、通電部に用いるには、電気伝導性の高い単層ナノチューブ(以下、SWCNTと略記する)を用いる必要があるが、SWCNTのうち、導電性の高い、いわゆる金属性SWCNTは1/3程度であり、残りは半導体性で電気抵抗が大きく、起電力が得られない。熱電変換部材にSWCNTを用いるには、SWCNTを精製して用いるか、基板上に反応を制御しながら、金属性SWCNTのみを直接形成する必要がある。これらの作製上の制約が大きな方法を用いることは、実用的には大きな課題である。   On the other hand, in order to provide a stress absorption structure in the element itself, a method is also disclosed in which flexible carbon nanotubes are set up perpendicular to the substrate to achieve high thermal conductivity and stress relaxation (see, for example, Patent Document 4). ). However, this method has a strong anisotropy, and it is not easy to produce such an element using carbon nanotubes that need to be joined with high orientation. In addition, single-walled nanotubes with high electrical conductivity (hereinafter abbreviated as SWCNT) need to be used for use in the current-carrying portion. Among SWCNTs, so-called metallic SWCNTs with high conductivity are about 1/3. The remainder is semiconducting and has a large electric resistance, and no electromotive force can be obtained. In order to use SWCNT for the thermoelectric conversion member, it is necessary to purify and use SWCNT or to form only metallic SWCNT directly on the substrate while controlling the reaction. It is a big problem practically to use a method with these restrictions on manufacture.

特開2004−265988号公報JP 2004-265988 A 特開2005−93454号公報JP 2005-93454 A 特表2006−507692号公報JP 2006-507692 A 特開2007−116087号公報JP 2007-116087 A

本発明は、上記課題に鑑みなされたものであり、その目的は、応力によって生ずる不良を抑制することができ、可撓性(フレキシビリティ)に優れ、かつ高い熱電変換能力を有する熱電変換素子を提供することにある。   The present invention has been made in view of the above problems, and its purpose is to provide a thermoelectric conversion element that can suppress defects caused by stress, has excellent flexibility, and has high thermoelectric conversion capability. It is to provide.

本発明の上記目的は、以下の構成により達成される。   The above object of the present invention is achieved by the following configurations.

1.熱電変換半導体及びアスペクト比が10以上で、太さが2nm以上、500nm以下の金属繊維の集合体が含有されていることを特徴とする熱電変換素子。   1. A thermoelectric conversion element comprising a thermoelectric conversion semiconductor and an aggregate of metal fibers having an aspect ratio of 10 or more and a thickness of 2 nm or more and 500 nm or less.

2.前記熱電変換半導体及び金属繊維の集合体が、一対の電極間に挟持されていることを特徴とする前記1に記載の熱電変換素子。   2. 2. The thermoelectric conversion element according to 1, wherein the aggregate of the thermoelectric conversion semiconductor and the metal fiber is sandwiched between a pair of electrodes.

3.前記金属繊維の集合体が、層状の熱電変換半導体を積層した構造を有することを特徴とする前記1または2に記載の熱電変換素子。   3. 3. The thermoelectric conversion element as described in 1 or 2 above, wherein the aggregate of metal fibers has a structure in which layered thermoelectric conversion semiconductors are laminated.

本発明により、熱電変換素子への金属繊維の集合体(以下、通電部ともいう)に、十分な応力緩和能と伝熱能及び電気伝導性を付与することによって、応力によって素子内に生ずる不良を抑制することができる熱電変換素子を提供することができた。   According to the present invention, by giving sufficient stress relaxation ability, heat transfer ability and electrical conductivity to an aggregate of metal fibers (hereinafter also referred to as current-carrying parts) to the thermoelectric conversion element, defects caused in the element due to stress can be prevented. The thermoelectric conversion element which can be suppressed was able to be provided.

本発明の熱電変換素子の構成の一例を示す概略断面図である。It is a schematic sectional drawing which shows an example of a structure of the thermoelectric conversion element of this invention. 本発明の熱電変換素子の構成の他の一例を示す概略断面図である。It is a schematic sectional drawing which shows another example of a structure of the thermoelectric conversion element of this invention.

以下、本発明を実施するための最良の形態について詳細に説明する。   Hereinafter, the best mode for carrying out the present invention will be described in detail.

本発明者は、上記課題に鑑み鋭意検討を行った結果、熱電変換半導体及びアスペクト比が10以上で、太さが2nm以上、500nm以下の金属繊維の集合体が含有されていることを特徴とする熱電変換素子により、応力によって生ずる不良を抑制することができ、可撓性(フレキシビリティ)に優れ、かつ高い熱電変換能力を有する熱電変換素子を実現することができた。   As a result of intensive studies in view of the above problems, the present inventor has a thermoelectric conversion semiconductor and an aggregate of metal fibers having an aspect ratio of 10 or more and a thickness of 2 nm or more and 500 nm or less. By using the thermoelectric conversion element, defects caused by stress can be suppressed, and a thermoelectric conversion element having excellent flexibility and high thermoelectric conversion ability can be realized.

以下、本発明の熱電変換素子の詳細について説明する。   Hereinafter, the details of the thermoelectric conversion element of the present invention will be described.

〔熱電変換素子の構成〕
本発明の熱電変換素子の構成について図を用いて説明する。なお、以下の図に示す熱電変換素子は、本発明の熱電変換素子の一例を示すものであり、本発明はここで例示する構成にのみ限定されるものではない。
[Configuration of thermoelectric conversion element]
The structure of the thermoelectric conversion element of this invention is demonstrated using figures. In addition, the thermoelectric conversion element shown in the following figures shows an example of the thermoelectric conversion element of this invention, and this invention is not limited only to the structure illustrated here.

図1は、本発明の熱電変換素子の構成の一例を示す概略断面図である。   FIG. 1 is a schematic cross-sectional view showing an example of the configuration of the thermoelectric conversion element of the present invention.

図1において、熱電変換素子10には、説明の便宜上絶縁性の基板を省略している。   In FIG. 1, an insulating substrate is omitted from the thermoelectric conversion element 10 for convenience of explanation.

図1に示す熱電変換素子10では、主として熱電変換半導体14からなる熱電変換半導体層15と電極基板11、12との間に、金属繊維16からなる通電部13が設置されている。通電部13は、熱電変換半導体層15の片側でも良いが、応力緩和の観点から、図1に示すように熱電変換半導体層15の両側に存在することが好ましい。なお、文中の熱電変換半導体14は、後述するとおり、温度差が与えられたとき、大きな起電力を生じる半導体(例えば、Bi−Te系化合物など)を指す。   In the thermoelectric conversion element 10 shown in FIG. 1, a current-carrying portion 13 made of a metal fiber 16 is installed between a thermoelectric conversion semiconductor layer 15 mainly made of a thermoelectric conversion semiconductor 14 and the electrode substrates 11 and 12. The energizing portion 13 may be on one side of the thermoelectric conversion semiconductor layer 15, but is preferably present on both sides of the thermoelectric conversion semiconductor layer 15 as shown in FIG. 1 from the viewpoint of stress relaxation. In addition, the thermoelectric conversion semiconductor 14 in the text indicates a semiconductor (for example, a Bi-Te compound) that generates a large electromotive force when a temperature difference is given, as will be described later.

図1に示す金属繊維16からなる通電部13は、適当な空隙を構成することで、可撓性を付与すると共に、十分な熱伝導性、電気伝導性を有することが必要である。通電部13は空隙部を有し、熱電変換素子にかかる応力を軽減、分散する効果を有する。空隙が存在しないと、外力印加時に電極11、12、通電部13、熱電変換半導体層15の各接合面、ないし熱電変換半導体層15にかかる応力の分散、軽減がされないため、最も弱い部分、例えば、電極11、12と通電部13、あるいは通電部13と熱電変換半導体層15の接合部分などに破壊が生じやすく、電気、熱抵抗の上昇、起電力低下の原因になる。   The current-carrying portion 13 made of the metal fiber 16 shown in FIG. 1 needs to have sufficient thermal conductivity and electrical conductivity while providing flexibility by forming an appropriate gap. The energization part 13 has a void and has an effect of reducing and dispersing the stress applied to the thermoelectric conversion element. If there is no gap, since the stress applied to each joint surface of the electrodes 11, 12, the energizing portion 13, the thermoelectric conversion semiconductor layer 15 or the thermoelectric conversion semiconductor layer 15 is not dispersed or reduced when an external force is applied, the weakest part, for example, In addition, the electrodes 11 and 12 and the energizing portion 13 or the junction between the energizing portion 13 and the thermoelectric conversion semiconductor layer 15 are likely to be broken, which causes an increase in electricity and thermal resistance and a decrease in electromotive force.

通電部13中の空隙比率は高いほど好ましいが、高すぎると熱伝導性、電気伝導性が低下し、その結果、起電力の低下を引き起こすため、適度な値が存在する。その値は実験的に求めることができるが、概ね、通電部13の全体積に対して、50体積%以上、99体積%以下であることが好ましい。   The higher the void ratio in the current-carrying portion 13, the better. However, if it is too high, the thermal conductivity and electrical conductivity are lowered, and as a result, the electromotive force is lowered. Although the value can be obtained experimentally, it is generally preferable that the value is not less than 50% by volume and not more than 99% by volume with respect to the total volume of the energizing part 13.

〔金属繊維〕
本発明に係る通電部を構成する金属繊維は、アスペクト比(本発明でいうアスペクト比とは、個々の粒子の長軸Aと短軸Bの長さ比(A/B)の平均値と定義する)の大きな金属粒子である。特に、アスペクト比が10以上の金属繊維であることが好ましい。
[Metal fiber]
The metal fibers constituting the current-carrying part according to the present invention have an aspect ratio (the aspect ratio in the present invention is defined as an average value of the length ratio (A / B) between the major axis A and the minor axis B of individual particles. Large metal particles. In particular, metal fibers having an aspect ratio of 10 or more are preferable.

金属繊維の形状としては、直線的な結晶であるウィスカー状、更に曲線的なワイヤー状など、いかなる形状でもよい。このような金属繊維を用いることで、通電部を構成する金属繊維同士の接点の数が少なくなり、可撓性を保ちつつ、高い電気、熱伝導性を維持し易いためである。   The shape of the metal fiber may be any shape such as a whisker shape that is a linear crystal, and a curved wire shape. This is because by using such metal fibers, the number of contact points between the metal fibers constituting the energization portion is reduced, and it is easy to maintain high electrical and thermal conductivity while maintaining flexibility.

本発明では、金属繊維のなかでも、特に、金属ナノワイヤと呼ばれる金属繊維材料を用いることが好ましい。   In the present invention, among metal fibers, it is particularly preferable to use a metal fiber material called a metal nanowire.

金属ナノワイヤとは、金属元素を主要な構成要素とする線状構造体で、金属繊維の中でも特に細線構造を有するものを指す。通常、金属繊維は溶融した金属を延伸することで形成されるが、金属ナノワイヤとは、原子スケールからnmサイズの直径を有する線状構造体で、金属塩等の還元反応と同時に、その太さのままで金属を成長、繊維化させるのが一般的な作製方法である。   The metal nanowire is a linear structure having a metal element as a main constituent element and refers to a metal fiber having a fine line structure. Usually, metal fibers are formed by stretching molten metal, but metal nanowires are linear structures with diameters from the atomic scale to the nm size, and their thickness is reduced simultaneously with the reduction reaction of metal salts and the like. A general production method is to grow and fiberize the metal as it is.

本発明に適用される金属ナノワイヤは、1つの金属ナノワイヤで長い導電パス、熱伝導パスを形成するため、平均長さが3μm以上であることが好ましく、さらには3〜500μmが好ましい。併せて、長さの相対標準偏差は40%以下であることが好ましい。   Since the metal nanowire applied to the present invention forms a long conductive path and heat conductive path with one metal nanowire, the average length is preferably 3 μm or more, and more preferably 3 to 500 μm. In addition, the relative standard deviation of the length is preferably 40% or less.

本発明においては、金属ナノワイヤの平均直径として2〜500nmが好ましく、30〜200nmであることがより好ましい。直径が太すぎる場合には、例えアスペクト比が大きくとも、半導体界面の一部に応力が集中し、接触が脆弱なりやすい傾向がある。適度な細さを有する場合、接触面積が同じであれば応力が分散され、接触が安定化する。逆に細すぎる場合、電気抵抗が急激に上昇して、熱電変換効率が下がるほか、通電部の熱伝導性が悪くなり、半導体の有効温度差が小さくなることで起電力が低下する場合がある。この傾向は、直径が30nm以下で顕著に現れ、2nm以下では特に顕著である。これらの直径は平均値での議論であるため、分布にばらつきのある場合は、平均値が好ましい範囲であっても必ずしも期待できる性能が得られない。そのため、直径の相対標準偏差は20%以下であることが好ましい。   In the present invention, the average diameter of the metal nanowire is preferably 2 to 500 nm, and more preferably 30 to 200 nm. If the diameter is too large, even if the aspect ratio is large, stress tends to concentrate on a part of the semiconductor interface, and the contact tends to be fragile. In the case of having an appropriate thinness, if the contact area is the same, the stress is dispersed and the contact is stabilized. On the other hand, if it is too thin, the electrical resistance will increase rapidly and the thermoelectric conversion efficiency will decrease, the thermal conductivity of the current-carrying part will deteriorate, and the effective temperature difference of the semiconductor will decrease, which may reduce the electromotive force. . This tendency is prominent when the diameter is 30 nm or less, and is particularly remarkable when the diameter is 2 nm or less. Since these diameters are discussions based on average values, when there is variation in distribution, performance that can be expected is not necessarily obtained even if the average value is within a preferable range. Therefore, the relative standard deviation of the diameter is preferably 20% or less.

本発明において、金属ナノワイヤの製造手段には特に制限はなく、例えば、液相法や気相法等の公知の手段を用いることができる。また、具体的な製造方法としても、特に制限はなく、公知の製造方法を用いることができる。例えば、Agナノワイヤの製造方法としては、Adv.Mater.,2002,14,833〜837;Chem.Mater.,2002,14,4736〜4745等、Auナノワイヤの製造方法としては特開2006−233252号公報等、Cuナノワイヤの製造方法としては特開2002−266007号公報等、Coナノワイヤの製造方法としては特開2004−149871号公報等の記載を参考にすることができる。特に、上述した、Adv.Mater.及びChem.Mater.で報告されたAgナノワイヤの製造方法は、水系で簡便にかつ大量にAgナノワイヤを製造することができ、また銀の導電率は金属中で最大であることから、本発明に係る金属ナノワイヤの製造方法として好ましく適用することができる。   In the present invention, the means for producing the metal nanowire is not particularly limited, and for example, known means such as a liquid phase method and a gas phase method can be used. Moreover, there is no restriction | limiting in particular as a specific manufacturing method, A well-known manufacturing method can be used. For example, as a method for producing Ag nanowires, Adv. Mater. , 2002, 14, 833-837; Chem. Mater. , 2002, 14, 4736-4745, etc. As a method for producing Co nanowires, a method for producing Au nanowires is disclosed in JP 2006-233252A, and a method for producing Cu nanowires is disclosed in JP 2002-266007 A, etc. Reference can be made to the description in Japanese Unexamined Patent Application Publication No. 2004-149871. In particular, Adv. Mater. And Chem. Mater. The method for producing Ag nanowires reported in 1 can produce Ag nanowires easily and in large quantities in an aqueous system, and the conductivity of silver is the largest among metals, so that the production of metal nanowires according to the present invention is possible. It can be preferably applied as a method.

〔通電部の作製〕
金属繊維による通電部の作製には、作製した金属繊維をシート化する方法を適用することができる。
(Production of current-carrying part)
A method of forming the produced metal fiber into a sheet can be applied to the production of the current-carrying part using the metal fiber.

シート化の方法としては、例えば、金属繊維とバインダー繊維(例えば、ポリビニルアルコール繊維)とを含有するスラリーを、湿式抄紙法により脱水プレスし、加熱乾燥によりシート化して金属繊維シートを作製する。次いで、表面温度が160℃程度の加熱ローラを用いて加熱圧着を行う。次いで、無酸素雰囲気下(例えば、水素ガス雰囲気)の連続焼結炉を用いて、金属繊維の融点を越えない温度範囲で加熱して、金属繊維間を融着させて、空隙部を有する金属繊維シート(通電部)を得る方法が挙げられる。   As a method for forming a sheet, for example, a slurry containing metal fibers and binder fibers (for example, polyvinyl alcohol fibers) is dehydrated and pressed by a wet papermaking method, and formed into a sheet by heat drying to produce a metal fiber sheet. Next, thermocompression bonding is performed using a heating roller having a surface temperature of about 160 ° C. Next, using a continuous sintering furnace in an oxygen-free atmosphere (for example, a hydrogen gas atmosphere), the metal fibers are heated in a temperature range that does not exceed the melting point of the metal fibers, and the metal fibers are fused to form a metal having voids. The method of obtaining a fiber sheet (electric conduction part) is mentioned.

通電部を構成する金属繊維は、それぞれ適当な空隙を含有することにより、可撓性を有すると共に、十分な熱伝導性、電気伝導性を有することが必要である。空隙中には空気が充満されていても良いし、不活性ガスが充填されていても良い。また、真空であっても良い。あるいは、可撓性の高い樹脂が含浸されている構造であることも好ましい。なお、樹脂は熱電変換素子の電気伝導性、熱伝導性に大きな寄与を及ぼさないので、その充填体積は空隙として扱う。   The metal fibers constituting the current-carrying part need to have sufficient thermal conductivity and electrical conductivity while having flexibility by containing appropriate gaps. The gap may be filled with air or may be filled with an inert gas. Moreover, a vacuum may be sufficient. Alternatively, a structure in which a highly flexible resin is impregnated is also preferable. In addition, since the resin does not greatly contribute to the electrical conductivity and thermal conductivity of the thermoelectric conversion element, the filling volume is treated as a void.

〔金属繊維の構成材料〕
本発明に係る金属繊維を構成する金属組成としては、特に制限はなく、貴金属元素や卑金属元素の1種または複数の金属から構成することができるが、貴金属(例えば、金、白金、銀、パラジウム、ロジウム、イリジウム、ルテニウム、オスミウム等)及び鉄、コバルト、銅、錫からなる群に属する少なくとも1種の金属を含むことが好ましく、導電性の観点からは、少なくとも銀を含むことがより好ましい。また、導電性と安定性(例えば、金属ナノワイヤの硫化や酸化耐性、及びマグレーション耐性)を両立するために、銀と、銀を除く貴金属に属する少なくとも1種の金属とを含むことも好ましい。本発明に係る金属ナノワイヤが2種類以上の金属元素を含む場合には、例えば、金属ナノワイヤの表面と内部で金属組成が異なっていてもよいし、金属ナノワイヤ全体が同一の金属組成を有していてもよい。
[Component materials of metal fibers]
There is no restriction | limiting in particular as a metal composition which comprises the metal fiber which concerns on this invention, Although it can comprise from the 1 type or several metal of a noble metal element and a base metal element, it is a noble metal (for example, gold, platinum, silver, palladium) , Rhodium, iridium, ruthenium, osmium, and the like) and at least one metal belonging to the group consisting of iron, cobalt, copper, and tin, and more preferably at least silver from the viewpoint of conductivity. Moreover, in order to make electroconductivity and stability (for example, the sulfidation of metal nanowire, oxidation resistance, and magnetization resistance) compatible, it is also preferable to contain silver and at least one metal belonging to a noble metal other than silver. When the metal nanowire according to the present invention includes two or more kinds of metal elements, for example, the metal composition may be different between the inside and the surface of the metal nanowire, or the entire metal nanowire has the same metal composition. May be.

高熱伝導率による変換効率の向上には、100W/(m・K)の熱伝導率を有する金属からなることが好ましく、例えば、2007理科年表に記載のデータから、下記の金属を選択することができる。例えば、亜鉛、アルミニウム、イリジウム、カリウム、金、銀、タングステン、銅、ベリリウム、マグネシウム、モリブデン等およびこれらを含有する合金が好ましい。更には、200W/(m・K)と更に高い熱伝導率を有する、アルミニウム、金、銀、銅、ベリリウム等およびこれらを含有する合金がより好ましい。   In order to improve the conversion efficiency due to high thermal conductivity, it is preferable to use a metal having a thermal conductivity of 100 W / (m · K). For example, the following metals should be selected from the data described in the 2007 scientific chronology. Can do. For example, zinc, aluminum, iridium, potassium, gold, silver, tungsten, copper, beryllium, magnesium, molybdenum, and alloys containing these are preferable. Furthermore, aluminum, gold, silver, copper, beryllium, and the like and alloys containing these having a higher thermal conductivity of 200 W / (m · K) are more preferable.

本発明において、金属ナノワイヤの長さや直径、アスペクト比の平均値は、十分な数のサンプルについて電子顕微鏡写真を撮影し、個々のサンプル像の計測値の算術平均から求めることができる。サンプルの長さは、本来直線状に伸ばした状態で測定するべきであるが、現実には屈曲している場合もあるため、電子顕微鏡写真から画像解析装置を用いてサンプルの投影直径及び投影面積を算出し、円柱体を仮定して算出してもよい(長さ=投影面積/投影直径)。また、長さや直径の相対標準偏差は、下式に示す測定値の標準偏差を平均値で除した値に100を乗じた値で表す。サンプル数は、少なくとも100個以上が好ましく、300個以上であることがさらに好ましい。   In the present invention, the average values of the length, diameter, and aspect ratio of the metal nanowires can be obtained from an arithmetic average of measured values of individual sample images by taking electron micrographs of a sufficient number of samples. The sample length should be measured in a linearly stretched state, but in reality it may be bent, so the projected diameter and projected area of the sample using an image analyzer from an electron micrograph. May be calculated assuming a cylindrical body (length = projected area / projected diameter). In addition, the relative standard deviation of length and diameter is represented by a value obtained by multiplying 100 by the value obtained by dividing the standard deviation of the measured value shown in the following formula by the average value. The number of samples is preferably at least 100 or more, and more preferably 300 or more.

相対標準偏差(%)=測定値の標準偏差/平均値×100
〔熱電変換半導体の選択〕
金属繊維と共に熱電変換素子を構成する熱電変換半導体の種類としては、ビスマス−テルル系(Bi−Te系)の半導体のほか、Si−Ge系の半導体、Pb−Te系の半導体などが適用可能である。その他、充填スクッテルダイト化合物、ホウ素化合物、亜鉛アンチモン、クラスレート、擬ギャップ系ホイスラー花化合物などがある。詳細は、例えば、「熱電変換システムの高効率化・高信頼化技術」(2006年、技術情報協会)等の記載を参考にできる。
Relative standard deviation (%) = standard deviation of measured value / average value × 100
[Selection of thermoelectric conversion semiconductor]
As the types of thermoelectric conversion semiconductors that constitute the thermoelectric conversion elements together with metal fibers, in addition to bismuth-tellurium (Bi-Te) semiconductors, Si-Ge semiconductors, Pb-Te semiconductors, etc. are applicable. is there. In addition, there are filled skutterudite compounds, boron compounds, zinc antimony, clathrates, pseudogap-type Heusler flower compounds, and the like. Details can be referred to, for example, the description of “Technology for improving efficiency and reliability of thermoelectric conversion systems” (2006, Technical Information Association).

これら半導体は、元の材料に、p型、n型半導体としての性質を付与するためのドーパントが添加されている。ドーパントを添加した後に高温加熱、焼成を行うと、ドーパントの含有が半導体内部で不均一化し、周囲の不純物の悪影響を受ける原因になるため必要以上の加熱は好ましくない。金属部との接合、一体化おいてある程度の焼成が必要な場合、比表面積の大きな繊維からなる通電部は、その焼成温度を下げられるため、この観点からも好ましい。   In these semiconductors, a dopant for imparting properties as p-type and n-type semiconductors is added to the original material. If high temperature heating and baking are performed after the dopant is added, the content of the dopant becomes non-uniform in the semiconductor and causes adverse effects of surrounding impurities. When a certain amount of firing is required for joining and integration with the metal part, a current-carrying part made of fibers having a large specific surface area is preferable from this viewpoint because the firing temperature can be lowered.

〔熱電変換半導体層との界面〕
また、通電部と熱電変換半導体との界面は、電気抵抗や熱抵抗が生じないように接合している必要がある。そのため、通電部と熱電変換半導体との界面には、若干量のNiやCr、Moなど、接着性を向上するような金属が存在することが好ましい。
[Interface with thermoelectric conversion semiconductor layer]
In addition, the interface between the energization part and the thermoelectric conversion semiconductor needs to be joined so that no electrical resistance or thermal resistance occurs. For this reason, it is preferable that a slight amount of metal such as Ni, Cr, or Mo that improves adhesiveness exists at the interface between the energization portion and the thermoelectric conversion semiconductor.

熱電変換素子内で、電気抵抗や熱抵抗が存在すると、熱電変換効率が低下する。例えば電気抵抗や熱抵抗による熱電変換能は、下記の式(1)、(2)のように変動する。   If electric resistance or thermal resistance exists in the thermoelectric conversion element, the thermoelectric conversion efficiency is lowered. For example, the thermoelectric conversion ability due to electric resistance or thermal resistance varies as in the following formulas (1) and (2).

式(1)
ΔTeff=ΔT/(1+4・Rth(κ/L))
式(2)
P=(S・ΔTeff/4・A/(ρ+4ρ
式(1)において、Rthは界面熱抵抗を表し、Lは熱電変換素子の長さ(膜厚)を表す。式(2)において、ρは抵抗率を表し、ρはコンタクト抵抗を表す。
Formula (1)
ΔT eff = ΔT / (1 + 4 · R th (κ / L))
Formula (2)
P = (S · ΔT eff) 2/4 · A / (ρ B + 4ρ C)
In Formula (1), Rth represents interfacial thermal resistance, and L represents the length (film thickness) of the thermoelectric conversion element. In equation (2), ρ B represents resistivity and ρ C represents contact resistance.

上記式(1)、(2)から分かるように、電気抵抗や界面熱抵抗は、変換効率を低くする。金属部の熱抵抗が大きいと、起電力が低下しやすい。   As can be seen from the above formulas (1) and (2), the electrical resistance and the interfacial thermal resistance lower the conversion efficiency. If the thermal resistance of the metal part is large, the electromotive force tends to decrease.

〔熱電変換素子の作製方法〕
本発明の熱電変換素子における熱電変換半導体層の作製方法としては、下記に示す方法を一例として挙げられる。
[Method for producing thermoelectric conversion element]
Examples of the method for producing the thermoelectric conversion semiconductor layer in the thermoelectric conversion element of the present invention include the following methods.

1)グリーンシートを用いた半導体前駆体のパターニング、焼成(有機物の除去、半導体の結晶化)
2)蒸着、スパッタ(マスクパターニング、半導体の蒸着膜の作製と金属層設置の複層化)
3)Bi−Te系材料では、急冷薄片の焼結結晶化、ないし結晶成長により作製した結晶からの切り出し
その後に焼成が必要な場合には、遠心焼成、擬HIP等の焼成方法を用いることもでき、これらにより、半導体結晶を緻密にし、高性能化することができる。
1) Patterning and firing of semiconductor precursor using green sheet (removal of organic substances, crystallization of semiconductor)
2) Vapor deposition, sputtering (mask patterning, semiconductor vapor deposition film fabrication and metal layer placement)
3) For Bi-Te-based materials, a sintered method such as centrifugal firing or pseudo-HIP may be used if firing is necessary after sintering and crystallization of rapidly cooled flakes or crystal growth. Thus, the semiconductor crystal can be made dense and high performance can be achieved.

電極は、一般的な金属電極が使用可能である。アルミニウムや銅、金、銀、などのほか、半田、グラファイトなども適用可能である。半導体層を、空隙を有する金属部で挟む構造をとる場合は、その金属部を電極として用いることが可能なので、必ずしも別に電極を設ける必要は無い。   As the electrode, a general metal electrode can be used. In addition to aluminum, copper, gold, silver, etc., solder, graphite, etc. are also applicable. In the case where the semiconductor layer is sandwiched between metal parts having voids, the metal part can be used as an electrode, and thus it is not always necessary to provide another electrode.

発電用のモジュール化には、p型とn型の半導体を含んだ素子を直列に接続した、いわゆる「π型素子」とすることが望ましい。π型素子では、吸熱側と放熱側をそれぞれ熱源、冷却源に対して有効に配置でき、発電効率を高め易いためである。また、本発明ではp型、n型半導体の少なくとも1つに半導体層と空隙を有する金属部が含有されていれば良いが、可撓性をより高めるためにp型、n型半導体両方に半導体層と空隙を有する金属部が含有されていることがより好ましい。   For power generation modularization, it is desirable to use a so-called “π-type element” in which elements including p-type and n-type semiconductors are connected in series. This is because in the π-type element, the heat absorption side and the heat dissipation side can be effectively arranged with respect to the heat source and the cooling source, respectively, and the power generation efficiency is easily improved. In the present invention, at least one of the p-type and n-type semiconductors only needs to contain a semiconductor layer and a metal part having a void. However, in order to increase flexibility, both the p-type and n-type semiconductors are made of semiconductor. It is more preferable that the metal part which has a layer and a space | gap is contained.

本発明では、π型素子を電気的に直列に接続したモジュールの可撓性が向上するため、曲面上の発熱体に貼り付けるといった、これまでに無い使用法が可能になる。例えば、蒸気配管、焼却炉、衣類といったこれまで単に廃熱として捨てられていた熱エネルギーを電力として利用する、いわゆるユビキタス発電を実現できると考えられる。   In the present invention, since the flexibility of the module in which the π-type elements are electrically connected in series is improved, an unprecedented usage such as pasting to a heating element on a curved surface becomes possible. For example, it is considered that so-called ubiquitous power generation that uses heat energy such as steam pipes, incinerators, and clothing that has been discarded as waste heat until now as electric power can be realized.

また、大面積の素子が安価に製造できるため、太陽電池のように光電変換された残りのエネルギーが熱に変換されるような装置と組み合わせて使用することも好ましい。   In addition, since a large-area element can be manufactured at low cost, it is also preferable to use it in combination with a device that converts the remaining energy photoelectrically converted into heat, such as a solar cell.

以下、実施例を挙げて本発明を具体的に説明するが、本発明はこれらに限定されるものではない。なお、実施例において「部」あるいは「%」の表示を用いるが、特に断りがない限り「質量部」あるいは「質量%」を表す。   EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "part by mass" or "mass%" is represented.

《金属繊維の作製》
〔銀ナノワイヤの作製〕
(銀ナノワイヤ1(Ag−1)の作製)
Adv.Mater.2002,14,833〜837に記載の方法を参考にして、還元剤としてエチレングリコール(以下、EGと略記)、保護コロイド剤兼形態制御剤としてポリビニルピロリドン(以下、PVPと略記)を使用し、かつ核形成工程と粒子成長工程を分離して、以下のような方法で、ワイヤー状銀粒子である銀ナノワイヤ1を作製した。
<< Production of metal fibers >>
[Production of silver nanowires]
(Preparation of silver nanowire 1 (Ag-1))
Adv. Mater. With reference to the method described in 2002, 14, 833 to 837, ethylene glycol (hereinafter abbreviated as EG) as a reducing agent, polyvinylpyrrolidone (hereinafter abbreviated as PVP) as a protective colloid agent and form control agent, And the nucleation process and the particle growth process were separated, and the silver nanowire 1 which is a wire-like silver particle was produced by the following method.

(核形成工程)
反応容器内で170℃に保持したEG液100mlを攪拌しながら、硝酸銀のEG溶液(硝酸銀濃度:1.5×10−4モル/L)10mlを、一定の流量で、1秒間で添加した。その後、140℃で10分間熟成を施し、銀の核粒子を形成した。熟成終了後の反応液は、銀ナノ粒子の表面プラズモン吸収に由来した黄色を呈しており、銀イオンが還元されて、銀ナノ粒子が形成されたことが確認された。
(Nucleation process)
While stirring 100 ml of EG solution maintained at 170 ° C. in the reaction vessel, 10 ml of EG solution of silver nitrate (silver nitrate concentration: 1.5 × 10 −4 mol / L) was added at a constant flow rate for 1 second. Thereafter, aging was carried out at 140 ° C. for 10 minutes to form silver core particles. The reaction solution after completion of ripening exhibited a yellow color derived from surface plasmon absorption of silver nanoparticles, and it was confirmed that silver ions were reduced and silver nanoparticles were formed.

(粒子成長工程)
上記の熟成を終了した核粒子を含む反応液を、攪拌しながら170℃に保持し、硝酸銀のEG溶液(硝酸銀濃度:1.0×10−1モル/L)100mlと、PVPのEG溶液(PVP濃度:5.0×10−1モル/L)100mlを、ダブルジェット法を用いて一定の流量で、200分を要して添加した。粒子成長工程において、20分毎に反応液を採取して電子顕微鏡で確認したところ、核形成工程で形成された銀ナノ粒子が時間経過に伴って、主にナノワイヤの長軸方向に成長しており、粒子成長工程における新たな核粒子の生成は認められなかった。
(Particle growth process)
The reaction liquid containing the core particles after completion of the ripening is kept at 170 ° C. with stirring, 100 ml of an EG solution of silver nitrate (silver nitrate concentration: 1.0 × 10 −1 mol / L), and an EG solution of PVP ( 100 ml of PVP concentration: 5.0 × 10 −1 mol / L) was added at a constant flow rate using the double jet method over 200 minutes. In the particle growth process, the reaction solution was collected every 20 minutes and confirmed with an electron microscope. As a result, the silver nanoparticles formed in the nucleation process grew mainly in the major axis direction of the nanowires over time. Thus, no new core particles were generated in the grain growth process.

(水洗工程)
粒子成長工程終了後、反応液を室温まで冷却した後、フィルターを用いて濾過し、濾別された銀ナノワイヤをエタノール中に再分散した。フィルターによる銀ナノワイヤの濾過とエタノール中への再分散を5回繰り返し、最終的に銀ナノワイヤのエタノール分散液を調製して、ワイヤー状の銀ナノワイヤ1を調製した。
(Washing process)
After completion of the particle growth step, the reaction solution was cooled to room temperature, filtered using a filter, and the silver nanowires separated by filtration were redispersed in ethanol. Filtration of silver nanowires with a filter and redispersion in ethanol were repeated five times, and finally an ethanol dispersion of silver nanowires was prepared to prepare wire-like silver nanowires 1.

得られた分散液を微量採取し電子顕微鏡で確認したところ、平均直径が1nm、平均長さ200nm、アスペクト比が200、熱伝導率が420W/(m・K)の銀ナノワイヤ粒子が形成されたことが確認できた。   When a small amount of the obtained dispersion was collected and confirmed with an electron microscope, silver nanowire particles having an average diameter of 1 nm, an average length of 200 nm, an aspect ratio of 200, and a thermal conductivity of 420 W / (m · K) were formed. I was able to confirm.

(銀ナノワイヤ2(Ag−2)〜銀ナノワイヤ11(Ag−11)の作製)
上記銀ナノワイヤ1(Ag−1)の作製において、核形成工程におけるEG液への硝酸銀のEG溶液の添加時間と熟成温度、及び粒子成長工程での硝酸銀のEG溶液と、PVPのEG溶液の添加時間を適宜調整した以外は同様にして、表1に示す直径及びアスペクト比を有する銀ナノワイヤ2(Ag−2)〜銀ナノワイヤ11(Ag−11)を作製した。
(Preparation of silver nanowire 2 (Ag-2) to silver nanowire 11 (Ag-11))
In the production of the silver nanowire 1 (Ag-1), the addition time and aging temperature of the silver nitrate EG solution to the EG solution in the nucleation step, and the addition of the silver nitrate EG solution and the PVP EG solution in the grain growth step Silver nanowire 2 (Ag-2) to silver nanowire 11 (Ag-11) having the diameters and aspect ratios shown in Table 1 were prepared in the same manner except that the time was appropriately adjusted.

〔銅ナノワイヤ1(Cu−1)の作製〕
上記銀ナノワイヤ7(Ag−7)の作製において、硝酸銀に代えて硫酸銅を用いた以外は同様にして、平均直径が100nm、平均長さ10μm、アスペクト比が100の銅ナノワイヤ1を作製した。
[Preparation of copper nanowire 1 (Cu-1)]
In the production of the silver nanowire 7 (Ag-7), a copper nanowire 1 having an average diameter of 100 nm, an average length of 10 μm, and an aspect ratio of 100 was produced in the same manner except that copper sulfate was used instead of silver nitrate.

〔白金ナノワイヤ1(Pt−1)の作製〕
上記銀ナノワイヤ7(Ag−7)の作製において、硝酸銀に代えて塩化白金を用いた以外は同様にして、平均直径が100nm、平均長さ10μm、アスペクト比が100の白金ナノワイヤ1を作製した。
[Production of platinum nanowire 1 (Pt-1)]
In the production of the silver nanowire 7 (Ag-7), a platinum nanowire 1 having an average diameter of 100 nm, an average length of 10 μm, and an aspect ratio of 100 was produced in the same manner except that platinum chloride was used instead of silver nitrate.

〔酸化マグネシウムナノワイヤ(MgO−1)の作製〕
J.Phys.Chem.B2002,106,7449−7452に記載の方法に従って、直径(短軸)が40nm、長さ(長軸)が4μm、アスペクト比が100のワイヤー状の酸化マグネシウムナノワイヤ1を作製した。
[Production of Magnesium Oxide Nanowire (MgO-1)]
J. et al. Phys. Chem. A wire-shaped magnesium oxide nanowire 1 having a diameter (minor axis) of 40 nm, a length (major axis) of 4 μm, and an aspect ratio of 100 was produced according to the method described in B2002, 106, 7449-7492.

《熱電変換素子の作製》
〔熱電変換素子1の作製〕
上記作製した銀ナノワイヤ1(Ag−1)を用いて、下記の方法に従って熱電変換素子1を作製した。
<Production of thermoelectric conversion element>
[Production of Thermoelectric Conversion Element 1]
The thermoelectric conversion element 1 was produced according to the following method using the produced silver nanowire 1 (Ag-1).

〈通電部の形成〉
上記作製した銀ナノワイヤ1(Ag−1)を、適当な割合でポリビニルブチラール樹脂(結着材)、フタル酸ジブチル(可塑剤)、エーテル型非イオン界面活性剤(フォスフォノール 東邦化学社製)、溶剤としてエタノール及びトルエンを加えてスラリー化し、これをポリエチレンテレフタレート(PET)フィルム上に、ドクターブレードで塗布、製膜してシート状にした。この時、塗布膜の厚さ、金属繊維の割合を適宜調整することで、焼成後に各種割合の空隙を有する金属繊維シート(10mm角)を得た。焼成は、金属繊維シートをPETフィルムごとアルミナボートに載せ、400℃で脱脂後、500℃で1時間焼成処理を行い、アルミナボート上に空隙率が約60体積%を有する通電部を得た。なお、電極間の総膜厚(図1に示す「A」)に占める通電部の膜厚は約70体積積%とした。なお、空隙率は、電子顕微鏡を用いて、その断面を観察して求めた。
<Formation of current-carrying part>
The silver nanowire 1 (Ag-1) produced above is polyvinyl butyral resin (binder), dibutyl phthalate (plasticizer), ether type nonionic surfactant (phosphonol Toho Chemical Co., Ltd.) at an appropriate ratio. Then, ethanol and toluene were added as a solvent to form a slurry, which was coated on a polyethylene terephthalate (PET) film with a doctor blade and formed into a sheet. At this time, by appropriately adjusting the thickness of the coating film and the ratio of the metal fibers, metal fiber sheets (10 mm square) having various ratios of voids after firing were obtained. For firing, the metal fiber sheet and the PET film were placed on an alumina boat, degreased at 400 ° C., and then fired at 500 ° C. for 1 hour to obtain a current-carrying part having a porosity of about 60% by volume on the alumina boat. In addition, the film thickness of the current-carrying part in the total film thickness between the electrodes (“A” shown in FIG. 1) was about 70 volume%. The porosity was determined by observing the cross section using an electron microscope.

〈熱電変換半導体層の作製〉
図2に示すように、15μmの高純度アルミ箔11上に、通電部13を敷設した後、別途単ロール急冷法で作製した急冷薄片状のp型のBi−Te半導体、n型のBi−Te半導体を熱電変換半導体14として仮プレス(200℃、10MPa)した。仮プレス物は、それぞれ10mm角で、膜厚は10μmとなるようにした。素子間の間隙は1mmとした。
<Preparation of thermoelectric conversion semiconductor layer>
As shown in FIG. 2, a current-carrying portion 13 is laid on a 15 μm high-purity aluminum foil 11, and then a rapidly cooled thin-flaked p-type Bi-Te semiconductor, n-type Bi— The Te semiconductor was temporarily pressed (200 ° C., 10 MPa) as the thermoelectric conversion semiconductor 14. The temporary press products were each 10 mm square and the film thickness was 10 μm. The gap between the elements was 1 mm.

〈積層型熱電変換素子の形成〉
15μmの高純度アルミ箔12上に、通電部13を敷設した後、上記仮プレス物を熱電変換半導体14、通電部、アルミ箔を順となるように重ね、3層構成とした。黒鉛中で36MPaの加圧下、270℃まで真空中で加熱、本プレスし、積層型の熱電変換素子1を得た。
<Formation of laminated thermoelectric conversion element>
After laying the current-carrying part 13 on the high-purity aluminum foil 12 of 15 μm, the temporary press product was stacked in the order of the thermoelectric conversion semiconductor 14, the current-carrying part, and the aluminum foil to form a three-layer structure. Under a pressure of 36 MPa in graphite, heating was performed up to 270 ° C. in a vacuum, and this pressing was performed to obtain a multilayer thermoelectric conversion element 1.

〔熱電変換素子2〜14の作製〕
上記熱電変換素子1の作製において、通電部を構成する金属繊維として、銀ナノワイヤ1(Ag−1)に代えて、表1に記載の各金属繊維を用いた以外は同様にして、熱電変換素子2〜14を作製した。
[Production of thermoelectric conversion elements 2 to 14]
In the production of the thermoelectric conversion element 1, the thermoelectric conversion element is the same except that each metal fiber shown in Table 1 is used instead of the silver nanowire 1 (Ag-1) as the metal fiber constituting the energization part. 2-14 were produced.

〔熱電変換素子15の作製〕
上記熱電変換素子1の作製において、通電部で金属繊維を用いなかった以外は同様にして、熱電変換素子15を作製した。
[Preparation of Thermoelectric Conversion Element 15]
In the production of the thermoelectric conversion element 1, a thermoelectric conversion element 15 was produced in the same manner except that no metal fiber was used in the energization portion.

《熱電変換素子の評価》
〔熱電変換効率の評価〕
上記作製した各熱電変換素子を、120℃の平板ホットプレート上に設置し、他面を20℃の水を通した金属ブロックで冷却した。その状態で、下部電極から得られた起電力値Aを測定し、熱電変換素子7の起電力値Aを100とした相対値を求めた。得られる相対電力値が大きいほど、熱電変換能の高い素子と考えられる。
<< Evaluation of thermoelectric conversion element >>
[Evaluation of thermoelectric conversion efficiency]
Each of the produced thermoelectric conversion elements was placed on a flat plate hot plate at 120 ° C., and the other surface was cooled with a metal block through which water at 20 ° C. was passed. In this state, the electromotive force value A obtained from the lower electrode was measured, and a relative value was obtained with the electromotive force value A of the thermoelectric conversion element 7 being 100. The larger the relative power value obtained, the higher the thermoelectric conversion capability.

〔折り曲げ耐性の評価〕
上記作製した各熱電変換素子を、φ20mmの円筒に長手方向が円周になるように巻きつける操作と、平面上に広げる操作を各5回繰り返した後、上記熱電変換効率の評価と同様の方法で起電力値Bを測定し、熱電変換効率の評価で求めた初期の起電力値Aに対する起電力値Bの劣化巾(%)を求めた。劣化巾が大きいと、マイナスの数値が大きくなり、その値が小さいほど可撓性が高いと考えられる。
[Evaluation of bending resistance]
The same method as the evaluation of the thermoelectric conversion efficiency after repeating the operation of winding each of the produced thermoelectric conversion elements around a φ20 mm cylinder so that the longitudinal direction is a circumference and the operation of spreading on a plane five times each. Then, the electromotive force value B was measured, and the deterioration width (%) of the electromotive force value B with respect to the initial electromotive force value A obtained by the evaluation of the thermoelectric conversion efficiency was obtained. If the deterioration width is large, the negative numerical value becomes large, and the smaller the value, the higher the flexibility.

以上により得られた結果を、表1に示す。   The results obtained as described above are shown in Table 1.

表1に記載の結果より明らかなように、本発明で規定する構成で、かつ通電部に特定の太さとアスペクト比を有する金属繊維を含む熱電変換素子は、優れた熱電変換効率を有すると共に、比較例に対し高い折り曲げ耐性を備えていることが分かる。   As is clear from the results shown in Table 1, the thermoelectric conversion element including the metal fiber having a specific thickness and aspect ratio in the current-carrying part in the configuration defined in the present invention has excellent thermoelectric conversion efficiency, It turns out that it has high bending tolerance with respect to a comparative example.

10 熱電変換素子
11、12 電極基板
13 通電部
14 熱電変換半導体
15 熱電変換半導体層
16 金属繊維
DESCRIPTION OF SYMBOLS 10 Thermoelectric conversion element 11, 12 Electrode board 13 Current supply part 14 Thermoelectric conversion semiconductor 15 Thermoelectric conversion semiconductor layer 16 Metal fiber

Claims (3)

熱電変換半導体及びアスペクト比が10以上で、太さが2nm以上、500nm以下の金属繊維の集合体が含有されていることを特徴とする熱電変換素子。 A thermoelectric conversion element comprising a thermoelectric conversion semiconductor and an aggregate of metal fibers having an aspect ratio of 10 or more and a thickness of 2 nm or more and 500 nm or less. 前記熱電変換半導体及び金属繊維の集合体が、一対の電極間に挟持されていることを特徴とする請求項1に記載の熱電変換素子。 The thermoelectric conversion element according to claim 1, wherein the aggregate of the thermoelectric conversion semiconductor and the metal fiber is sandwiched between a pair of electrodes. 前記金属繊維の集合体が、層状の熱電変換半導体を積層した構造を有することを特徴とする請求項1または2に記載の熱電変換素子。 The thermoelectric conversion element according to claim 1, wherein the aggregate of metal fibers has a structure in which layered thermoelectric conversion semiconductors are stacked.
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