DE102010031829A1 - Thermoelectric device useful as a temperature sensor, a thermoelectric cooler, a thermoelectric heater or a thermoelectric power generator, comprises a flexible ceramic substrate and a layer arrangement, which is formed onto the substrate - Google Patents

Abstract

The thermoelectric device comprises a flexible ceramic substrate and a layer arrangement, which is formed onto the substrate, where the layer arrangement comprises a flat bottom electrode, a flat top electrode, a flat p-doped area and a flat n-doped area, which are arranged next to each other between the bottom electrode and the top electrode and are alternatively switched in row, and a passivation structure, which is flatly formed between the adjacent p-doped and n-doped areas and is thermally insulated. The passivation structure has breakthroughs. The thermoelectric device comprises a flexible ceramic substrate and a layer arrangement, which is formed onto the substrate, where the layer arrangement comprises a flat bottom electrode, a flat top electrode, a flat p-doped area and a flat n-doped area, which are arranged next to each other between the bottom electrode and the top electrode and are alternatively switched in row, and a passivation structure, which is flatly formed between the adjacent p-doped and n-doped areas and is thermally insulated. The passivation structure has breakthroughs and the flat p-doped and n-doped areas are formed in the breakthroughs. The substrate made of plates or films of the materials consisting of metal, aluminum, zinc, silicon or copper. The substrate comprises an electrically insulated layer, which is arranged between the substrate and the bottom electrode and is formed on the substrate at the side opposite to the bottom electrode. The bottom electrode is formed in the substrate. The passivation structure contains an organic material, polymer or flexible material as main material, and is made of photo-lacquer. The breakthroughs have one of the structures such as triangular, hexagonal, square, quadratic and circular. An independent claim is included for a method for producing a thermoelectric device.

Description

The The invention relates to a thermoelectric device with thin layers

Background of the invention

thermoelectric Properties of materials have been the subject for many years research to thermoelectric effects to transport heat or to convert heat into electrical energy use. Despite many encouraging results, especially in Recently, a wide application has not yet taken place.

The thermoelectric properties of materials reflect the circumstance again, that the heat transfer z. T. from the electronic System is worn, that means with the transport of Charge carriers. Conversely, for the transport of charge carriers also to a heat flow. The connection of electrical and heat flow is through the so-called Seebeck coefficient specified. This is for semiconductors typically some 100 μV / K and is thus considerably larger than for Metals (~ 1 μV / K).

frequently it is proposed to use the thermoelectric effect for recovery of energy from naturally occurring temperature differences or to recover from waste heat. In general, that can only be be successful when the investment costs for a thermoelectric Component in a reasonable proportion to the generated Energy or performance stand. It is an object of the invention To provide thermocouples with a very low cost.

to To solve this problem, the thermocouple is preferred with a solvent method (for example, coating or printing). These methods are characterized by low Investment costs in the manufacturing equipment. Still have they usually have a high material yield. After all is the use of inexpensive film substrates (eg metal foil) possible in a roller coating plant.

By This production process can in particular large-scale Thermocouples are made economically sensible. This allows the exploitation of heat sources, which is a big one Surface, but only a slight temperature difference to Environment. Such heat sources are common to find in nature.

For Solvent methods can use different materials be used. The best known are organic materials (small molecules or oligo- or polymers) that are common can be processed in suitable solvents. However, inorganic materials can also be common be processed by solvent method. typically, these materials are provided as functionalized (nano) particles, and the solubilizing functional group after deposition separated in a baking step. Examples of inorganic Semiconductor materials already used in solvent processes are: Si, ZnO, TiO2, GaN, CdTe, Copper indium gallium (di) selenide (CIGS), Cu2S and others. Due to the "natural" solubility properties Of the organic materials, these are preferred for the embodiment of this invention, in particular for the use as thermoelectrically active functional materials.

The However, proposed component structure may also partially or completely with other processes, in particular vacuum deposition processes getting produced. Again, it is possible, large-scale components and also processing on roll substrates possible.

organic Semiconductors have been isolated in the literature for thermoelectric Applications suggested, however, are the appropriate material properties little studied. Only recently are organic Semiconductors more in the focus of systematic research advised, so for this work some comparative values be available.

COP

wobei σ die elektrische Leitfähigkeit, S der Seebeck-Koeffizient und λ die thermische Leitfähigkeit des Materials ist. Werte für Z·T größer 1 erlauben, thermoelektrische Anwendungen eines Materials in Erwägung zu ziehen (T ist die mittlere Temperatur, bei der das Bauelement betrieben wird).The performance of thermoelectric materials can be described by a figure of merit. It contains the relevant material properties and describes the maximum possible efficiency both for heating / cooling elements and for power generation. at the consideration of the coefficient of performance is to be noted, however, that this maximum efficiency u. U. far from the technically interesting range of maximum performance of the device is achieved. The coefficient of performance Z is

where σ is the electrical conductivity, S the Seebeck coefficient and λ the thermal conductivity of the material. Values for Z · T greater than 1 allow thermoelectric applications of a material to be considered (T is the average temperature at which the device operates).

In the literature, the required material sizes can only be found sporadically. More recent work has focused on doped polymer systems or charge-transfer complexes. Typical sizes are given in the table. material reference Conductivity σ (S / cm) Seebeck coefficient S (mV / K) Thermal conductivity λ (W / mK) Doped polymers PEDOT: PSS Jiang08 50 (Pressling) 13 0.2 (pressed) Organo-soluble PANI: HCl Yakuphanoglu08 ~ 1e-6 70 Doped poly (2,7-carbazole) Aich09 160 34 Charge-transfer complex BEDT-TTF: TCNQ Wüsten08 ~ 1e-2 (Pressling) ~ 50 (TMTSF) 2ClO4 charge transfer salt Choi86 2

It It can be seen that for doped polymers very high To achieve conductivities. The Seebeck coefficient is low (presumably because of the very high doping level). To qualitatively similar Assessments come with charge transfer complexes.

There with lower doping concentration the conductivity increases, However, the Seebeck coefficient decreases, it is interesting to one to study low molecular weight organic material system.

Thermoelectric properties of the system ZnPc: F4-TCNQ

For the investigations were selected the material system ZnPc: F4-TCNQ. The chemical structure of the materials can be seen in the graph.

ZnPc (zinc phthalocyanine) is a hole-transporting organic semiconductor. F4-TCNQ (tetrafluoro-tetracyanoquinodimethane) acts as a p-dopant in this host system. It is already known from the literature that F4-TCNQ leads to an increase in the conductivity of the matrix. The Seebeck coefficient for a doped thin film of this material system is in the range of a few hundred μV / K. The materials are also readily available.

to Sample preparation, the powders of both materials were in proportion 10: 1 (ZnPc: F4-TCNQ) mixed and to a compact of 0.5 mm thickness pressed (sample D). For comparison, was also a compact made of pure ZnPc (Sample U). The use of organic Although materials in such macroscopic geometries are unusual. However, the required measuring methods are available for these samples are available, as opposed to thin-layer samples, for no established methods for sample preparation be available.

The graphic ( 1 ) shows the electrical conductivity and the thermal conductivity of the samples. It can be seen that the conductivity of the doped sample is indeed higher than that of the undoped ones. It increases with increasing temperature. The conductivity of about 2 · 10 ^-4 S / cm determined for the undoped sample corresponds to the measurement limit of the apparatus. From corresponding experiments on vapor deposited thin films, it is known that undoped ZnPc has a conductivity of 10 ^-8 S / cm or smaller. For doped thin films, the conductivity at room temperature is> 10 ^-2 S / cm (maennig01). It is to be expected that the transport of charge carriers, as opposed to a vapor-deposited layer, is considerably hindered for the compact, since the compact is less compact and grain boundaries occur. In addition, it is not ensured that the mixture of matrix and dopant is equally homogeneous as in a mixed thin layer.

For the thermal conductivity is for both Samples found a value of about 0.2 W / mK. It is remarkable in addition to the absolute level of the value, that is the thermal conductivity not changed by the doping. This means that charge carriers only insignificant for the transport of heat through the organic Contribute solids. This has important implications for the applicability of the material.

With the aid of the Seebeck coefficient of ZnPc: F4-TCNQ of about 400 μV / K (maennig01) known from the literature, the coefficient of performance of the material system can be calculated:

in this connection were available in an optimistic estimate so far the more favorable values of the thin-film structure used.

It shows that the coefficient of performance of the organic material despite a suitable Seebeck coefficient when operating at room temperature is very low.

Use as thermogenerator

In order to arrive at an assessment of the practical applicability of organic thin films, various scenarios are investigated. Here, 2 material systems are compared. On the one hand, an idealized organic material is considered whose thermoelectric parameters are considered feasible. However, this combination of material sizes represents a significant difference from current measurements. For comparison, data are used for bismuth telluride thin films. This material has been well studied for thermoelectric applications. Hypothetical organic material Bismuth telluride http://en.wikipedia.org/wiki/Bismuth_telluride Thermal conductivity (W / mK) 0.1 1 Electrical conductivity (S / cm) 0.4 1e3 Seebeck coefficient (μV / K) 200 -287 COP 0.000016 / K 0.004 / K

Out The coefficient of performance gives the maximum possible efficiency for the conversion of thermal energy into electrical Energy. The temperatures of the warm and cold reservoir go by one. For applications for heat sinks at room temperature (T = 330 K) and a temperature difference of 5 K to the heat source results in a maximum efficiency of only 0.002%.

In order to ensure operation in the area of maximum efficiency, the electrical load resistance and the dimension of the individual thermoelectric element must be matched to one another. For a layer thickness of 100 nm and square individual elements with the dimensions 0.1 × 0.1 mm ² results in an optimal load resistance of 2.5 kΩ for a total area of the device of 1 cm ² (ie an arrangement of 10,000 individual elements on this base) , The electrical power in this case is about 10 mW (or 10 mW / cm ² ). This value refers to a complete filling of the available area with active elements, so it should be understood as an upper estimate of an actually possible value.

This value can be compared with results of miniature thermocouples from the company Micropelt, which are based on a Bi ₂ Te ₃ technology. 1.2 mW / cm ² are given here. It should be noted that this is a real value, that in particular the area utilization is only <10% and that the efficiency of this device is considerably higher than the organic device. Technical challenges for a thin-film component advantages Potential benefit flexibility Easy integration into the application geometry, use in functional textiles Production by solvent processes Low unit costs due to simple production Low thermal conductivity Lower minimum thickness of the thermocouple → lower material consumption disadvantage Low mechanical stability Low thermal stability at T> 370 K

Out the comparison of the material parameters of organic layers with the Parameters of bismuth telluride shows that the significantly lower Performance of organic material by others Benefits must be balanced to target an application believe it. This could, in particular, low production costs (by using solvent processes and scalability of the component) and the adaptation to the desired application geometry due to the potential flexibility of the device play a role. The power requirement of the electrical consumer but it can only be small. A conceivable application is the Supply of electrical functional clothing with electrical energy, which is fed from the body heat.

It However, it should not be forgotten that the typical component geometry a thermoelectric element significantly different from those of other organic Components such as organic light-emitting diodes or organic Thin-film transistors deviates. A transmission the manufacturing processes for those structures on thermoelectric Application requires a high adaptation effort. Continue to exist especially for thin layers the difficulty that for maintaining the temperature gradient, a high heat flow is needed. Such heat flow can be in Practical situations difficult to sustain continuously become. This may require on thick-film technologies for manufacturing to access the thermoelectrically active layer. This can also mean new challenges.

In Regarding the thermoelectric properties of an organic Materials appear interesting areas of application, which are cost-effective, large-scale solution or a flexible one Need thermocouple.

Regarding the materials used is in particular the combination of a molecular dopants with a matrix with high mobility advantageous. This makes it possible to adopt the in Table 2 Show material parameters.

Usually is used for thermoelectric components, which are next to each other on a substrate, a series circuit as a structure for selected p- and n-type semiconductor regions.

For organic devices, the pad may be relatively large for these p and n regions, e.g. B. in mm ² range. This simplifies the structuring of the p and n regions. The layer thickness of the organic layers should be large enough to ensure a sufficient thermal resistance thereby preserving the temperature gradient (or in other words limiting the heat flow). Depending on the application, it is necessary that the layers of the p- and n-type materials are slightly thicker and in the micrometer range. Thick film production processes are more suitable in this case than thin film production processes.

Under these conditions, the following building blocks and their production processes are proposed for a component structure:
A substrate is provided. This should have sufficient thermal conductivity and sufficient mechanical stability. An advantageous choice are substrates made of metal, such as. As discs or films of aluminum, zinc, silicon or copper. Electrically insulating substrates such as ceramic discs can also be used. If the substrate is electrically conductive, it may be provided with an electrically insulating layer. The electrically insulating layer may be made of organic materials, for. As polymers (eg., Polyimides, Parylene), oxide layers or other layers.

in the The following example is an aluminum foil with a PMMA as insulating Layer used.

The Base electrode should be the surfaces later used by the p- and n-type areas. A complete Covering these areas is not necessary as the p and n-type areas have a certain own conductivity. The base electrode can be replaced by shadow masks with thermal evaporation in the Vacuum or even produced by printing. The bottom electrode must be sufficiently conductive around the internal electrical Resistance of the device to keep low. Consequently, should conductive materials, such as conductive polymers (eg, PEDOT-based blends such as polyethylene dioxithiophene doped with polysulfonic acids, PEDOT: PSS, or conductive Polyaniline) or metals such as copper, gold, silver, aluminum for the electrodes are used.

In a preferred example, ITO electrodes are deposited by sputtering. The ITO has a layer thickness of 100 nm. The graphic ( 2 ) gives an illustration of a possible arrangement of the ITO electrodes.

next, a passivation structure is provided. This serves to define the area for the p- and n-type areas, the thermal and electrical insulation between ground and cover electrode produce and to ensure the mechanical stability. The openings (openings) in the passivation layer preferably have a hexagonal structure around the surface of the active material (organic semiconductor) as much as possible to choose. For the sake of process simplification but are also more rectangular, square or round shapes conceivable. The passivation structure can by evaporation, chemical Vapor deposition (CVD), solvent coating, Photolithography and / or printing methods are produced. helpful Materials are polyimides, photoresists (eg SU-8 or AZ1518 [Microchemicals]), PMMA (polymethyl methacrylates), insulating oxides, parylenes. If necessary, the layers can also be crosslinked (Crosslinking) are stabilized.

In In a preferred example, the passivation is made from AZ1518 and exposed through a shadow mask. The passivation layer has a layer thickness of 500 nm.

The graphic ( 3 ) shows the added passivation layer having hexagonal openings.

Thereafter, the openings are filled with the active p and n materials. The top surface of the Passivation can be changed (eg by making the surface hydrophobic or hydrophilic) so that the active material is not deposited on the passivation. Such changes in the passivation structure may e.g. By using suitable self-assembled monolayers (eg, by using fluoroalkylsilanes (FAS) and octadecyltrimethoxysilanes (ODS)), by plasma treatment of the surface, or by treatment with acids or alkalis. This simplifies the structuring of the active layer. The p- and n-type materials can be applied by ink jet printing and / or spraying methods. The active layers should contain materials that have high hole and / or electron mobility, ie greater than 10 ^ -1 cm ² / Vs. These materials may consist of polymers or of so-called small molecules. As polymers one could use poly (3-hexylthiophene) (P3HT), polyfluorene or copolymers (with repeating thiophene or fluorene units). Suitable small molecules are phthalocyanine (eg Zn phthalocyanine or perfluorinated Zn phthalocyanine), fullerenes (including C60, soluble PCBM (phenyl-C61-butyric acid methyl ester) or fluorinated fluorene), pentacenes, porphyrins (eg Zn Porphyrin), oligothiophenes or fluorinated oligothiophenes. Furthermore, the active materials should contain dopants that provide the conductivity of the p or n types in the respective openings. Suitable doping materials are tetracyano quinodimethane (TCNQ) or tetrafluoro tetracyano quinodimethane (F4TCNQ), or similar materials which have a strong acceptor character. These materials induce p-type conductivity.

Further suitable dopants are tetrathiafulvalene (TTF) and their derivatives, metal complexes such as cobalt salts or dopants such as LCV (leucocrystal violet base). These materials are characterized that they have a strong donor-like character, respectively have low ionization potential. Induce these materials the n-type conductivity. Charge transfer complexes or radicals Ionic salts like TCNQ: TTF can also act as active materials be used.

In A preferred example was the p-type region with F4-TCNQ made of doped P3HT. The n-type area were made out with LCV made of doped PCBM. Both layers have a thickness of 500 nm and are by solution processing of the materials formed in the appropriate openings.

The graphic ( 4 ) shows the added p- and n-type regions (distinguished by different colors). In this exemplary illustration, the p- and n-type regions are alternately executed. In the figure, the base areas for the p and n areas are the same size. In many practical applications, however, the ratio of the areas of the p and n regions should be adapted to the thermal conductivities or resistivities of the p-type and n-type materials or doped materials.

After that the cover electrode is provided on the structure. The cover electrode provides electrical contact between the p- and n-type regions ago. The formed p / n strip pairs are connected in series, so as to provide at the poles A and B, the thermoelectric voltage. The Cover electrode should be the areas covered by the p- and n-type areas are covered, cover. A complete cover is not necessary, because the p- and n-type areas have a certain own conductivity. The cover electrode may be through shadow masks be prepared with thermal evaporation in a vacuum, or also by printing. The materials can be from the same group of materials be selected for the base electrode suitable is.

In a preferred example, silver electrodes (100 nm thick) were used produced by a shadow mask during vacuum evaporation. A 500 nm thick passivation layer of parylene was subsequently provided.

The graphic ( 5 ) shows the added cover electrode arrangement.

ever additional features may be added as needed be, for. B. a passivation layer or over the cover electrostructure a second substrate. The materials for the passivation layer can be made from the materials required for the passivation layer selected on the first substrate. The second substrate may be selected from the group of materials suitable for the first substrate are suitable to be selected.

literature

• Aich01: RD Aich et al., Chem. Mater., 2009, 21 (4), 751
• Choi86: M.-Y. Choi et al., Phys. Rev. B, 1986, 34 (11), 7727
• Jiang08: F.-X. Jiang, Chin. Phys. Lett., 2008, 25 (6), 2202
• Mannig01: Maennig et al., Phys. Rev. B, 2001, 64, 195208
• Wüsten08: J. Deserts, K. Potje-Kamloth, J. Phys. D, 2008, 41, 135113
• Yakuphanoglu08: F. Yakuphanoglu et al., J. Electron. Mater., 2008, 27 (6), 930

glossary

• Base electrode: electrode closest to the substrate, with n- or p-type layer (region) in electrical contact, preferred also in direct contact
• Cover electrode: with n- or p-type layer (area) in electrical Contact, preferably in direct contact, n- or p-type layer (area) is between ground electrode and Cover electrode arranged
• Electrically insulating: layer or substrate which is not electrically conductive, preferably, the layer has an electrical resistance greater than 10 ^ 6 ohm cm ² ; more preferably, an electrically insulating layer or substrate is made of an insulating material having a conductivity less than 10 ^ -8 S / cm ^ -1.
• Thermal conductivity of the substrate: the substrate should be made of a material that has a conductivity greater or equal to the thermal conductivity of the glass (-1 W / (m.K)), preferably greater or equal to 10 W / (m.K) (steel), more preferably larger or equal to 200 W / (m.K) (Al).
• Thermally insulating: thermal conductivity smaller or equal to 0.5 W / (m.K) (epoxy), preferably less than or equal to 0.15 W / (m.K), more preferably less than or equal to 0.03 W / (m.K).
• Flat Layers: Layers are a relationship from the longest side to the layer thickness of at least 1 to 10, preferably from 1 to 100, more preferably from 1 to 1000 to have. The substrate is preferably thicker than the other layers.

Preferred thicknesses:

Electrode layer thickness are preferably greater than 50 nm. Electrode layer thicknesses are preferably less than 10 microns, preferably less than 300 nm.

The Layer thickness of the p and n regions is preferably larger as 100 nm, preferably larger than 1 μm; layer thickness the p and n regions are preferably less than 100 μm; p and n regions can have different layer thicknesses exhibit; the different thicknesses can at least partly the different electronic and thermoelectric Balance material properties.

Electric doping

The n- and p-doping in this invention is also referred to as electrical Doping referred to.

It It is known to treat organic semiconductors by doping their electrical properties, in particular their electrical Conductivity, change, as with inorganic semiconductors, such as silicon semiconductors, is the case. This is done by generating charge carriers in the matrix material an increase in the initially low conductivity and depending on the type of dopant used a change achieved in the Fermi level of the semiconductor. A doping leads in this case an increase in the conductivity of Charge transport layers, whereby ohmic losses are reduced, and to an improved transfer of charge carriers between contacts and organic layer. The doping in the conductivity sense is due to a charge transfer from the dopant to a close lying matrix molecule (n-doping, electron conductivity increased), or by the transfer of an electron from a matrix molecule to a nearby dopant (p-doping, hole conductivity increased). The charge transfer may be incomplete or complete done and can be z. By interpretation of vibrational bands of a FTIR (Fourier-transformed infrared spectroscopy) Determine measurement.

dopants

The patent application DE10307125 (corresponding US2005 / 040390 ) discloses a doped organic semiconductor material with increased carrier density and effective charge carrier mobility, obtainable by doping with a chemical compound, in particular a cationic dye, from which a doping active molecular group is split off. Cationic dyes of the present invention may be pyronine B chloride or crystal violet chloride.

The patent application DE10338406 (corresponding US2005 / 061232 ) discloses the use of a Dopants (in particular of leuco bases of cationic dyes) from which certain leaving groups are split off in order to obtain a doping effect. A leuco base according to the invention may be, for example, leuco crystal violet.

The patent application DE10347856 (corresponding WO05036667 ) discloses the use of transition metal complexes as donors in an organic semiconductor material. A transition metal complex according to the invention can be, for example, bis (2,2'-terpyridine) ruthenium.

The patent application DE10357044 (corresponding US2005121667 ) discloses the use of quinones or 1,3,2-dioxaborines or their derivatives as acceptors in organic semiconductor materials. Acceptors according to the invention are, for example, 2,2,7,7-tetrafluoro-2,7-dihydro-1,3,6,8-dioxa-2,7-dibora-pentachloro-benzo [e] pyrene or 1,4,5, 8-tetrahydro-1,4,5,8-tetrathia-2,3,6,7-tetracyanoanthraquinone or 1,3,4,5,7,8-hexafluoronaphtho-2,6-quinonetetracyanomethane.

The patent application DE102004010954 (corresponding WO05086251 ) discloses the use of electron-rich metal complexes as donors in organic semiconductor materials. Electron-rich metal complexes according to the invention are, for example, tetrakis (1,3,4,6,7,8-hexahydro-2H-pyrimido [1,2-a] pyrimidinato) dichromate (II) or tetrakis (1,2,3,3a, 4 , 5,6,6a, 7,8-decahydro-1,9,9b-triazaphenalenyl) ditungsten (II).

In In many cases it is beneficial if for one p-doping (n-doping) the LUMO of a p-dopant (HOMO of the n-dopant) maximum 0.5 eV larger (maximum 0.5 eV smaller) is the HOMO (LUMO) of a p-type (n-type) matrix. Here are according to the convention, the sizes HOMO or LUMO as amount equal to the ionization potential or electron affinity, but with opposite Sign.

n-dopants (donors or as donors designated)

molecule and / or neutral radical with a HOMO level (solid-state ionization potential) typically more positive than -5.5 eV (preferably more positive as -5 eV). The HOMO of donors can be derived from cyclovoltammetric Determine the oxidation potential. Alternatively, the Reduction potential of the donor cation in a salt of the donor be determined. Molar mass of the donor between 100 and 2000 g / mol, preferably between 200 and 1000 g / mol. Molar doping concentration between 1: 1000 (acceptor molecule: matrix molecule) and 1: 2, preferably between 1: 100 and 1: 5, more preferably between 1: 100 and 1:10. In individual cases, there is also a doping ratio into consideration, in which the doping molecule with a higher Concentration is applied as 1: 2, for example when a especially high conductivity is needed.

The donor can emerge from a pre-cursor during the film-making process or the subsequent film-forming process (see Werner et al. DE 103 07 125.3 ) form first. The HOMO level of the donor given above then refers to the resulting species.

While molecular dopants (i.e., dopants greater than 6, in particular more than 20 atoms) due to their size ensure high stability of the doped layers, can in special or less demanding cases less molecular dopants can be used. these can for example, alkali metals, or alkali metal compounds, or Be alkaline earth metals or alkaline earth compounds. examples are cesium, lithium, rubidium, potassium, cesium, Magnesium; Cesium carbonate, cesium oxalate, lithium Carbonate.

In In other cases, the p-dopant may also be quaternary Ammonium compound (eg Tetraalkylamonium) or by others cationic compounds are provided. This can for example: crystal violet cation, imidazole cation, benzimidazole cation, Pyridinium cation. If cations are used as dopants, forms a matrix molecule in the layer that leads to charge neutrality needed anion.

p-dopants (acceptors)

Molecule and / or neutral radical having a LUMO level more negative than -4 eV (preferably more negative than -4.5 eV, more preferably more negative than -5 eV). The LUMO of the acceptor can be determined from cyclovoltammetric measurements of the reduction potential. Molar mass of the acceptor between 100 and 2000 g / mol, preferably between 200 and 1000 g / mol, more preferably between 300 g / mol and 2000 g / mol. Molar doping concentration between 1: 1000 (acceptor molecule: matrix molecule) and 1: 2, preferably between 1: 100 and 1: 5, more preferably between 1: 100 and 1:10. In individual cases, a doping ratio is also considered, in which the doping molecule is used with a concentration higher than 1: 2, for example when a particularly high conductivity is needed. The acceptor may first form from a pre-cursor during the layering process or the subsequent layering process. The above LUMO level of the acceptor then refers to the resulting species.

While molecular dopants (i.e., dopants greater than 6, in particular more than 20 atoms) due to their size ensure high stability of the doped layers, can in special or less demanding cases less molecular dopants can be used. these can For example, metal oxides such as WO3 or MoO3, but also Lewis acids like FeCl3 or SbCl5. Iodine can also be used as a p-dopant become. Furthermore, the p-dopants can also be replaced by acid radicals be formed. In the simplest case, this can be a chloride anion (Cl-), but also be perchlorate anion, but also compounds with Acid residues such as sulfonates (eg polystyrene sulfonate (PSS), Tosylate). FeCl4 and SbCl6 subclass also fall into this category. When anions are used as dopants, forms in the layer a matrix molecule needed for charge neutrality Cation.

Hole transport materials (p-type Materials)

When Matrix materials for hole transport layers (p-type layers) may, for example, benzidine derivatives such as MeO-TPD, Spiro-TAD, NPD, etc are used. Especially are hole transport materials with a high mobility advantageous to high conductivity at low doping concentration guarantee. A low doping concentration allows a high Seebeck coefficient. The mobility for Holes should therefore be larger than 10 ^ -2 cm 2 / Vs, preferably greater than 10 ^ -1 cm2 / Vs. Such mobilities are common for crystalline transport layers possible. Suitable materials are, for example, phthalocyanines (such as phthalocyanine copper) or pentacene or its derivatives.

matrix materials for hole transport layers are usually neutral nonradical conjugated molecules. By doping with acceptor connections become correspondingly simple (rarely several times) charged cations of the matrix material produced. In the case of education of a simply loaded cation this is a radical cation. The contains layer formed from matrix material and dopant ie neutral molecules of the matrix material and by doping formed cations of the matrix material.

in the general case, the charge state of the Matrix molecules changed by one or more positive charges. For example, if the matrix material itself is an anion, is through the doping of the anion into a neutral molecule or a Transferred cation.

Hole transport materials for organic components usually have an oxidation potential in Range of 0 V vs. Fc / Fc + to 0.9 V vs. Fc / Fc + on.

In front especially when components are manufactured using solvent processes are to be, are also polymeric matrix materials into consideration. They are subject to similar requirements for the mobility and the oxidation potentials. A suitable matrix material For example, oligo- or polythiophenes or their Be derivatives.

Suitable hole transport materials:

Electron transport materials (n-type Materials)

As matrix materials for electron transport layers (n-type layers), for example, fullerenes such as C60, oxadiazole derivatives such as 2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole, quinoxaline based compounds such as bis (phenylquinoxalines), or oligothiophenes, perylene derivatives, such as. B. perylenetetracarboxylic dianhydride, naphthalene derivatives, such as. As naphthalenetetracarboxylic dianhydride, or other electron transport materials are used, as described for. In AP Kulkarni et al., Chem. Mater. 2004, 16, 4556 are described.

It is advantageous when the matrix materials for electron transport layers be chosen so that the resulting layer a possible has low sensitivity to exposure to air. One The decisive parameter here is the reduction potential of the Matrix material. This should be advantageous bigger as -1.5V vs. Fc / Fc +, in particular larger as -1 V vs. Fc / Fc + are selected. A special high air stability is used for matrix materials with a reduction potential greater than 0.8V vs. Fc / Fc + reached.

The figure showed some well-suited matrix materials for air-stable electron-transport layers:

Quinolinato complexes, for example of aluminum or other main group metals, where the quinolinato ligand can also be substituted, can furthermore be used as matrix materials for electron transport layers. In particular, the matrix material may be tris (8-hydroxyquinolinato) aluminum. Other aluminum complexes with O and / or N donor atoms may also be used become. The quinolinato complexes may contain, for example, one, two or three quinolinato ligands, the other ligands preferably complexing with O and / or N donor atoms to the central atom, such as, for example, the Al complex below.

matrix materials for electron transport layers are usually neutral non-radical conjugated molecules. By doping with Donorverbindungen are accordingly easy (rarely several times) charged Anions of the matrix material produced. In case of formation of a Simply charged Anions this is a radical anion. Made of matrix material and Dotand formed layer thus contains neutral molecules of the matrix material and anions of the matrix material formed by doping.

in the general case, the charge state of the Matrix molecules changed by one or more negative charges. For example, if the matrix material itself is a cation, is through the doping of the cation into a neutral molecule or a Converted anion.

matrix materials for electron transport layers in organic light emitting diodes often have a reduction potential between -1.9 V vs. Fc / Fc + and -2.4 V vs. Fc / Fc + on.

Especially are electron transport materials with a high mobility advantageous to high conductivity at low doping concentration to ensure. A low doping concentration allows a high Seebeck coefficient. The mobility for Therefore, electrons should be larger than 10 ^ -2 cm2 / Vs, preferably greater than 10 ^ -1 cm2 / Vs. Such mobilities are often for crystalline ones Transport layers possible.

In front especially when components are manufactured using solvent processes are to be, are also polymeric matrix materials into consideration. They are subject to similar requirements for the mobility and the reduction potentials. A suitable matrix material may be, for example, polyfluorene or derivatives thereof.

When Matrix material can also phenanthrolines be used, which may be substituted or unsubstituted, in particular Aryl-substituted, for example phenyl or naphthyl-substituted, or also, for example, bathocuproine (BCP). In particular, bathophenanthroline (Bphen) can be used as a matrix material.

Of Further, as matrix materials and heteroaromatics in particular triazole derivatives are used, if appropriate also pyrroles, imidazoles, triazoles, pyridines, pyrimidines, pyridazines Quinoxalines, pyrazinoquinoxalines and the like. The heteroaromatics are preferably substituted, in particular aryl-substituted, for example, phenyl or naphthyl substituted. Especially The below triazole can be used as a matrix material.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 10307125 [0051, 0058]
• US 2005/040390 [0051]
• - DE 10338406 [0052]
• US 2005/061232 [0052]
• - DE 10347856 [0053]
• WO 05036667 [0053]
• - DE 10357044 [0054]
• US 2005121667 [0054]
• - DE 102004010954 [0055]
• WO 05086251 [0055]

Cited non-patent literature

• - http://en.wikipedia.org/wiki/Bismuth_telluride [0022]
• AP Kulkarni et al., Chem. Mater. 2004, 16, 4556 [0068]

Claims (18)

Thermoelectric device, with a substrate and a layer assembly formed on the substrate, the Layer arrangement comprising: - a flat Base electrode, A flat top electrode, - areal p-doped regions and n-type planar regions, the between the base and the cover electrode arranged side by side and are alternately electrically connected in series, and - one Passivation structure, each between adjacent p-doped and n-doped areas formed flat and electrically and is designed thermally insulating. Component according to Claim 1, characterized that the Passivierungsstruktur has breakthroughs and the areal p- and n-doped areas in the respective Breakthroughs are formed. Component according to Claim 1 or 2, characterized that the substrate is flexible. Component according to at least one of the preceding Claims, characterized in that the substrate made Washers or foils of the following materials are: metal, aluminum, Zinc, silicon or copper. Component according to Claim 1, characterized that the substrate is a ceramic substrate. Component according to at least one of the preceding Claims, characterized in that the substrate a electrically insulating layer between the substrate and the base electrode is arranged. Component according to Claim 1, characterized the substrate has an electrically insulating layer, that on the substrate on the opposite side of the base electrode Page is formed. Component according to Claim 1, characterized the base electrode is formed on the substrate. Component according to at least one of the preceding Claims, characterized in that the passivation structure contains an organic material as a main material. Component according to at least one of the preceding Claims, characterized in that the passivation structure contains a polymer as a main material. Component according to at least one of the preceding Claims, characterized in that the passivation structure contains a flexible material as the main material. Component according to Claim 1, characterized the passivation structure is formed from a photoresist. Component according to Claim 1, characterized that the passivation structure has openings in where the planar p- and n-doped regions formed are, with the breakthroughs at least one of the following Structures have: triangular, hexagonal, square, square and round. Method for producing a thermoelectric component, wherein the method comprises the following steps: - preparing a planar substrate, - optionally: application of an electrically insulating layer on the side of the base electrode, - optionally: application of an electrically insulating layer on the opposite side of the substrate to the base electrode , - application of at least two conductive ground electrode strips; Plotting a passivation structure which only partially covers the base electrode strips and contains openings, plotting at least one p-doped region and plotting at least one n-doped region in the respective apertures, so the n- and p-doped regions from the same side relative to the substrate of at least one ground electrode strip are electrically contacted, and - Application of at least two conductive top electrode strips, wherein the p and n regions are electrically connected in series by the base electrode strips and cover electrode strips. Method according to claim 12, characterized in that that the passivation structure by a printing process from a Solution or melt is produced. Method according to claim 12, characterized in that that the passivation structure is made by photolithography becomes. Method according to claim 12, characterized in that that the p- and n-doped areas are characterized by a printing process a solution or melt can be made. Using a device according to one of the previous Claims as a temperature sensor, thermoelectric cooler, thermoelectric heater or thermoelectric generator.

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