KR20160078580A - Manufacturing Method For High Crystalline Thermoelectric Film - Google Patents

Abstract

The present invention provides a method for manufacturing a high crystalline thermoelectric film which includes a step of manufacturing a poly (3- hexythiopene) film by bar-coating the upper part of a substrate with a coating solution including poly (3- hexythiopene) (P3HT). The present invention provides a high crystalline P3HT film according to the manufacturing method. Thereby, a thermoelectric element with improved thermoelectric property can be obtained. Also, because the method for manufacturing the P3HT of the present invention can manufacture a uniform film with large size, a large-sized thermoelectric element can be efficiently manufactured.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a high-

The present invention relates to a method for producing a thermally-conductive film having high crystallinity.

Because thermoelectric materials can convert thermal energy into electrical energy, much research has been done on future energy materials. Researches on thermoelectric materials and devices have been developed since the 1950s and have developed thermoelectric properties two to three times higher than those of existing ones over a period of years. Bi-Te, Pb-Te, Si-Ge And Fe-Si-based alloys are the most widely used materials.

The thermoelectric performance index showing the energy conversion efficiency of these thermoelectric materials showed a value of less than 1 at room temperature, and the maximum cooling efficiency obtained through this was about 8%, which was limited to various electronic devices. Since the 1960 's, it was difficult to improve the thermoelectric performance index. However, due to the development of nanotechnology, three parameters of thermoelectric performance index could be separated and increased. This is the main reason for the improvement of the thermoelectric performance index in the 2000s. In the 2000s, as a thermoelectric material, Bi ₂ Te ₃ , PbTe, ZnSb ₃ , SiGe, BeSi ₂ , MSb ₃ (M = Co, Rb, In), CoFe ₃ Sb, Ba ₈ Si ₄₆ , NaCo ₂ Ox, CaCo ₄ O ₉ , and so on. Recently, a variety of materials ranging from compound semiconductors to ceramics have been studied. Recently, a superlattice made of these materials, a thermal conductivity reduction structure using a phonon glass-electron crystal, a strong scattering electromagnetic field, And heavy femion have been proposed to improve the thermoelectric performance index continuously.

Most efficient thermoelectric materials are made of inorganic materials including the above-mentioned rare elements, and thus have a difficulty in high price, brittleness, difficulty in large-area deposition, or utilization as industrialization technology.

On the other hand, organic materials have lower toughness, elasticity and low thermal conductivity than inorganic materials, and can be processed at a lower cost. In recent years, researches on thermoelectric devices using organic materials have been actively carried out.

Among the organic materials, conductive thermoelectric materials have lower thermoelectric properties than inorganic thermoelectric materials, but they are recognized as materials that can be applied to flexible, printing, and low cost thermoelectric devices because of their good processability and flexibility. In particular, the thermoelectric properties of conductive polymers such as polypyrrole, polyaniline, polycarbazole, polythiophene, poly (3,4-ethylenedioxythiophene) (PEDOT) and poly (4-styrene sulfonic acid) (PSS)

In order to improve the thermoelectric properties of the polymer film to a high level, the electrical conductivity of the conductive polymer PEDOT: PSS was increased to a level of 1,260 S / cm up to 1,260 S / cm using a hydrazine solution, and the PEDOT: PSS thin film Have been reported.

Among the various polymer thermoelectric materials, a conjugated polymer having a high electrical conductivity is mainly used, but the conjugated polymer has a very low solubility in a solvent, so that a process for thermoelectric conversion is difficult. However, since poly (3-hexylthiophene) (P3HT) has excellent processability, it is a material suitable for a process for thermoelectric conversion. This is because many other conjugated polymers such as PEDOT have low solubility in solvents, while P3HT has a high solubility in organic solvents and can be applied to printing processes such as bar coating, screen printing and ink jet printing.

However, despite the above advantages, according to the data of the reported papers and the like, the thermoelectric property of the P3HT film is relatively low, so it is essential to improve the thermoelectric property for thermoelectric conversion.

In this regard, Japanese Patent Registration No. JP-A-2002-119771 discloses a method for producing a film using polythiopene, wherein the inorganic thermoelectric material is compounded with an organic thermoelectric material, thereby being excellent in workability as an organic thermoelectric material, Thermoelectric materials which are superior to inorganic thermoelectric materials and exhibit n-type thermoelectric properties have been reported.

Accordingly, in the present invention, a thermoelectric film having a high crystallinity and a thermoelectric device having improved thermoelectric properties have been developed using a wire-bar coating method, and the present invention has been completed.

Japanese Patent No. 2002-119771 (registered on April 24, 2009)

 J. Mater. Chem. A, vol.2 (2014) p.7288-7294

It is an object of the present invention to provide a method of manufacturing a thermoelectric film having high crystallinity.

In order to achieve the above object,

(3-hexylthiophene) (P3HT) on a substrate to form a poly (3-hexylthiophene) film, wherein the poly (3-hexylthiophene) to provide.

Further, according to the present invention,

A thermoelectric film produced by the above production method is provided.

Further,

A thermoelectric film produced in the manufacturing room; And

And an electrode provided on the thermoelectric film.

Further,

A process for producing a poly (3-hexylthiophene) film by bar-coating a coating liquid containing poly (3-hexylthiophene) (P3HT) on a substrate,

And has a thermoelectric property of 30 ㎼ / mk ² or more.

In the present invention, a method for producing a P3HT film using a wire-bar coating method and a highly crystalline P3HT film produced thereby can improve the thermoelectric properties. Further, since the method of producing the P3HT film of the present invention can easily produce a uniform film over a large area, there is an advantage that it is very efficient in manufacturing a large area thermoelectric element.

1 is a schematic view of a wire-bar coating process according to the present invention;
2 is a graph showing the film thickness according to the concentration of P3HT;
3 is a photograph of the P3HT film produced in step 2 of Examples 1 and 2 and Comparative Examples 1 to 3 observed using an atomic force microscope (AFM);
4 is a graph showing the results of analysis of an FeCl ₃ -doped P3HT film prepared in the step 2 of Examples 1 and 2 and Comparative Examples 1 to 3 using an X-ray diffractometer;
5 is a photograph of the P3HT film prepared in Examples 1 and 2 and Comparative Examples 1 to 3 observed using an atomic force microscope;
6 is a graph showing the results of analysis of FeCl ₃ -doped P3HT films prepared in Examples 1 and 2 and Comparative Examples 1 to 3 by using an X-ray diffractometer;
FIG. 7 is a graph showing the thermoelectric characteristics of FeCl ₃ -doped films prepared in Examples 1 and 2 and Comparative Examples 1 to 3.

Hereinafter, the present invention will be described in detail.

According to the present invention,

(3-hexylthiophene) (P3HT) on a substrate to form a poly (3-hexylthiophene) film, wherein the poly (3-hexylthiophene) to provide.

Hereinafter, a method of manufacturing a thermoelectric film according to the present invention will be described in detail.

Generally, as the organic thermoelectric material, a conjugated polymer having a high electrical conductivity among organic materials can be mainly used. However, since the conjugated polymer generally has a very low solubility in a solvent, it is disadvantageous in that the process for thermoelectric conversion is very difficult. However, since poly (3-hexylthiophene) (P3HT) has excellent solubility in an organic solvent, it is a material suitable for a process for thermoelectric conversion.

In the method for producing a thermoelectric film according to the present invention, a coating liquid containing poly (3-hexylthiophene) (P3HT) is prepared and then the coating liquid is bar-coated on the substrate to form a poly (3-hexylthiophene) Can be manufactured.

First, as a conductive polymer, a coating solution can be prepared by dissolving P3HT having excellent solubility in a solvent, wherein the solvent is selected from the group consisting of Dicholrobenzene (DCB), chloroform (chloroform), toluene (Toluene), tetrachloroethane , TCE), chlorobenzene (CB) and the like can be used, but dichlorobenzene is preferably used.

Next, a poly (3-hexylthiophene) film can be prepared by bar-coating the above prepared coating solution on the substrate.

A schematic view of a bar-coating according to the present invention is shown in FIG. 1, and coating can be carried out, for example, using a wire bar at a rate of about 10 mm / s.

After the coating, the P3HT film may be dried at room temperature and then heat-treated at a temperature of 90 to 180 ° C. If the temperature of the heat treatment is less than 90 ° C, the solvent may remain in the film. If the temperature exceeds 180 ° C, the polymer film may be damaged by heat.

Further, it may further include an interlayer including a polymer between the substrate and the P3HT film. The intermediate layer serves to prevent separation of the substrate and the P3HT thermoelectric film and to form a smooth layer on the substrate. The polymer may be polyimide, polyvinylidene (PVDF), polyethylene terephthalate, polycarbonate, polystyrene, polymethylmethacrylate (PMMA), polyethylene naphthalate (PEN), polyether sulfone , But is not limited thereto.

The intermediate layer may be formed by spin coating, drop casting, doctor blading, spray coating, or bar coating, for example, on the polymer precursor.

Meanwhile, the method may further include doping dopants on the P3HT film.

This can be done by immersing the P3HT film formed in a solvent in a dopant dissolved in a solvent, wherein the dopant is FeCl ₃ , NOPF ₆ , (CF ₃ SO ₂ ) ₂ N ^- , AuCl ₃ and , 5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ), and the like, but it is preferable to use iron chloride (FeCl ₃ ).

Thereafter, a heat treatment may be performed at a temperature of about 50 to 100 DEG C in order to remove excess doping agent, and to remove other remaining solvent.

The present invention also provides a thermoelectric film produced by the above production method.

The thermoelectric film is a P3HT film having improved thermoelectric properties, and the thickness of the thermoelectric film is preferably 3.0 to 5.0 mu m. If the thickness of the thermoelectric film is less than 3.0 탆, a film having a low crystallinity can be formed. As a result, the thermoelectric properties of the thermoelectric film are relatively low. When the thickness exceeds 5.0 탆, And the solvent may be difficult to remove in the film.

Further,

Thermoelectric film; And

And an electrode provided on the thermoelectric film.

The thermoelectric device according to the present invention can be manufactured by patterning a thermoelectric film formed on a substrate with a certain width and width, and then stacking electrodes on the thermoelectric film using a thermal evaporation method.

The characteristics of the thermoelectric film are evaluated by a figure of merit, an electromotive force according to temperature difference (Seebeck coefficient), a thermal conductivity and an electric conductivity, and expressed as ZT = S ² σT / κ.

Where Z is the performance index, S is the Seebeck coefficient, σ is the electrical conductivity (S / cm), κ is the thermal conductivity (W / mK), and T is the absolute temperature (K). In general, the larger the Seebeck coefficient and the electrical conductivity, and the lower the thermal conductivity, the higher the figure of merit of the thermoelectric semiconductor, and the energy conversion efficiency by thermoelectric conversion is improved. At this time, since it is difficult to directly measure the thermal conductivity of the film, a power factor (S ² σ) based on the square of the Seebeck coefficient and the product of the electric conductivity is used as an alternative for evaluating the thermoelectric properties.

The thermoelectric device according to the present invention can exhibit high thermoelectric properties by significantly increasing the electrical conductivity as compared with the conventional thermoelectric device.

Further,

A process for producing a poly (3-hexylthiophene) film by bar-coating a coating liquid containing poly (3-hexylthiophene) (P3HT) on a substrate,

And has a thermoelectric property of 30 ㎼ / mk ² or more.

Hereinafter, a method for improving the thermoelectric characteristics of the thermoelectric film according to the present invention will be described in detail.

In the method for improving the thermoelectric properties of the thermoelectric film according to the present invention, a P3HT film can be prepared by coating a coating solution containing poly (3-hexylthiophene) (P3HT) on the substrate by a bar coating method.

At this time, the P3HT concentration of the coating solution is preferably 50 to 150 mg / ml.

If the concentration of P3HT is less than 50 mg / ml, there is a problem of low thermoelectric properties and electrical conductivity due to a small amount of conductive polymer. When the concentration exceeds 150 mg / ml, poly (3-hexylthiophene) (P3HT) May not be dissolved and a uniform film can not be formed.

As shown in FIG. 1, the coating solution may be coated on a substrate by a bar-coating method using a wire-bar to form a P3HT film. The thermoelectric characteristics of the P3HT film formed by the coating solution may significantly increase the whitening coefficient and electrical conductivity, And the thermoelectric property of the P3HT film, which has been reported in the past, can be surpassed to provide a thermoelectric property with a power factor of 30 ㎼ / mk ² or more.

In addition, the method of manufacturing the thermoelectric film can be easily applied to a thermoelectric film formed by various methods, and the thermoelectric property can be efficiently improved. Further, it can be applied to a mixture type of a conductive polymer and an inorganic thermoelectric material, so that the present invention can be applied to improvement of thermoelectric properties of various thermoelectric materials.

Hereinafter, the present invention will be described more specifically with reference to Examples.

However, the following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Example 1 Preparation of FeCl ₃ -doped P3HT Film 1

P3HT from Sigma-Aldrich was used to prepare the thermoelectric films used in the present invention.

Step 1: A polyimide precursor was synthesized by the method described in a previous document (Org. Electron. 2009, 10, 12-17), spin-coated on a glass substrate (76 mm x 26 mm) To form a mid-layer interlayer. At this time, the thickness of the formed polyimide intermediate layer was about 60 nm.

Step 2: To prepare the P3HT film, the solution was dissolved in? -Dichlorobenzene so that the concentration of P3HT was 50 mg / mL, and the solution was stirred with a magnetic stirrer to prepare a coating solution. The coating solution was coated on the polyimide intermediate layer formed in Step 1 through a bar-coating method. At this time, a wire-bar having a diameter of 1.3 cm wound with a wire having a diameter of 0.21 mm was used, and coating was performed at a speed of about 10 mm / s.

Thereafter, after drying for 2 hours at room temperature, heat treatment was performed on a hot plate at 90 占 폚 for 10 minutes and at 150 占 폚 for 30 minutes.

Step 3: The P3HT film heat-treated in step 2 was immersed in a 0.03 M FeCl ₃ solution dissolved in a solvent nitromethane for one hour. Subsequently, the resultant was washed with methanol to remove excess FeCl ₃ , and then heat-treated at 90 ° C for 10 minutes to remove the residual solvent to prepare FeCl ₃ -doped P3HT film.

≪ Example 2 > Preparation of FeCl ₃ -doped P3HT film 2

The procedure of Example 1 was repeated except that the paste was prepared by stirring in a mortar so that the concentration of P3HT was 150 mg / mL in Step 2 of Example 1 to prepare FeCl ₃ -doped P3HT film was prepared.

≪ Comparative Example 1 > Preparation of FeCl ₃ -doped P3HT film 3

A P3HT film doped with FeCl ₃ was prepared in the same manner as in Example 1 except that the coating liquid was prepared so that the concentration of P3HT was 10 mg / mL in the step 2 of Example 1.

≪ Comparative Example 2 > Preparation of FeCl ₃ -doped P3HT film 4

A P3HT film doped with FeCl ₃ was prepared in the same manner as in Example 1 except that the coating solution was prepared so that the concentration of P3HT was 20 mg / mL in the step 2 of Example 1.

≪ Comparative Example 3 > Preparation of FeCl ₃ -doped P3HT film 5

A P3HT film doped with FeCl ₃ was prepared in the same manner as in Example 1 except that the coating solution was prepared so that the concentration of P3HT was 30 mg / mL in the step 2 of Example 1.

≪ Comparative Example 4 > Preparation of FeCl ₃ -doped P3HT film 5

P3HT film doped with FeCl ₃ was prepared by the method described in the prior art (Energy Environ. Sci., 2012, 5, p.9639-9644). 8. At this time, the coating method of the P3HT film disclosed in the above- (Drop-casting) method was used.

≪ Comparative Example 5 > Preparation of FeCl ₃ -doped P3HT film 6

P3HT films doped with FeCl ₃ were prepared according to the method described in the prior art (Energy Environ. Sci., 2012, 5, p.8351-8358). 8. At this time, the coating method of the P3HT film disclosed in the above- (Drop-casting) method was used.

≪ Comparative Example 6 > Preparation of NOPF ₆ -doped P3HT film 1

P3HT films doped with NOPF ₆ were prepared by the method described in the prior art (Phys. Rev. B 2010, 82, 115454), wherein the coating method of the P3HT film disclosed in the prior art is a drop- Were used.

<Experimental Example 1>

The thickness of the P3HT film prepared by varying the concentration of the P3HT solution in Examples 1 and 2 and Comparative Examples 1 to 3 was measured and the results are shown in FIG.

As shown in Fig. 2, the thickness was in the range of 520 nm to 4.1 탆 according to the concentration of P3HT, and the thickness was increased when the concentration was less than 50 mg / ml, . Thus, the thicknesses of the films prepared in Examples 1 and 2 were 4.0 탆 and 4.1 탆, respectively, and there was no significant difference.

<Experimental Example 2> AFM analysis

In order to examine the structure and shape of the P3HT film not doped with FeCl ₃ , the P3HT film prepared in step 2 of Examples 1 and 2 and Comparative Examples 1 to 3 was subjected to atomic force microscopy (AFM) The results are shown in Fig.

3 (a) is Comparative Example 1 in which the P3HT concentration of the coating liquid is 10 mg / ml, Comparative Example 2 in which (b) is 20 mg / ml, Comparative Example 3 in which 30 mg / / mL in Example 1, (e) is an AFM photograph of the FeCl ₃ -doped P3HT film prepared in Step 2 of Example 2 at 150 mg / mL.

As shown in FIG. 3, it can be seen that the nanowire morphology on the film surface becomes more apparent as the concentration of P3HT increases.

Meanwhile, in order to examine the structure and shape of the P3HT film doped with FeCl ₃ , the P3HT films prepared in Examples 1 and 2 and Comparative Examples 1 to 3 were observed using an atomic force microscope, Respectively.

5 (a) shows Comparative Example 1 in which the P3HT concentration of the coating liquid is 10 mg / ml, Comparative Example 2 in which (b) 20 mg / ml, Comparative Example 3 in which 30 mg / / mL in Example 1, (e) is an AFM photograph of the FeCl ₃ -doped P3HT film prepared in Example 2 at 150 mg / mL.

As shown in FIG. 5, the presence of particles having a diameter of 25 to 130 nm was observed on the surface of the P3HT film doped with FeCl _{3, which} is a dopant, but the surface morphology of each film showed a similar shape regardless of the concentration.

This can be interpreted as a morphological change of the P3HT film due to the insertion of the dopant, that is, a structural change of the P3HT film in a nanowire-like structure in the form of nanoparticles.

<Experimental Example 3> XRD analysis

FeCl ₃ is to determine the crystallinity of the P3HT film according to the presence or absence of doping, the Examples 1, 2 and Comparative Example 1 of the FeCl ₃ is not doped P3HT film prepared in Step 2 of 1 to 3 X-ray diffractometer ( X-ray diffractometer). The results are shown in FIG.

4 (a) is Comparative Example 1 in which the P3HT concentration of the coating liquid is 10 mg / ml, Comparative Example 2 in which (b) is 20 mg / ml, Comparative Example 3 in which 30 mg / / mL in Example 1, (e) shows the XRD pattern of the undoped P3HT film prepared in Step 2 of Example 2 at 150 mg / mL.

As shown in Fig. 4, as the coating liquid and the film thickness increase, the intensity of the peak increases, indicating that the crystallinity of the P3HT film is improved.

In particular, it can be seen that although the thicknesses are similar in the XRD patterns of (d) 50 mg / mL and (e) 150 mg / mL, the crystallinity of the P3HT film is influenced by the preparation method of the coating solution.

When a coating solution having a high concentration of 150 mg / mL is prepared by using a stirrer, the crystallinity of the P3HT film produced can be further improved because the P3HT chains are aligned in the coating liquid by shear force.

Meanwhile, the XRD patterns of FeCl ₃ -doped P3HT films prepared in Examples 1 and 2 and Comparative Examples 1 to 3 are shown in FIG.

6 (a) is Comparative Example 1 in which the P3HT concentration of the coating liquid is 10 mg / ml, Comparative Example 2 in which (b) is 20 mg / ml, Comparative Example 3 in which 30 mg / ml is in (c) / mL in Example 1, (e) shows the XRD pattern of the FeCl ₃ -doped P3HT film prepared in Example 2 at 150 mg / mL.

As shown in FIG. 6, it can be seen that the XRD peak shifted at a lower angle than the films shown in FIG. 4 due to the dopant insertion.

Also, in the case of Example 2, which was a film produced by coating with a paste having a concentration of 150 mg / mL, it was confirmed that the intensity of the primary peak of Example 1, which was a film made of a solution having a concentration of 50 mg / mL, have.

It can be seen from the above results that the concentration of the coating solution and the thickness of the film affect the molecular chain packing of P3HT after the doping process.

&Lt; Experimental Example 4 >

In order to evaluate the thermoelectric properties of the P3HT films of Examples 1 and 2 and Comparative Examples 1 to 6, the electrical conductivity and the whiteness coefficient were measured to calculate the thermoelectric performance.

First, a thermoelectric element was prepared to measure the whiteness factor. Specifically, a 50 nm thick gold (Au) electrode was thermally deposited on the P3HT film prepared in Examples 1, 2 and Comparative Examples 1 to 6, Respectively. The width of the electrode was 5 mm.

In order to measure the whiteness coefficient of the fabricated devices, a whitish counting instrument was used. The thermocouple performance was evaluated from the measured electrical conductivity and whiteness coefficient.

The experimental results of the thermoelectric properties of the FeCl ₃ -doped films prepared in Examples 1 and 2 and Comparative Examples 1 to 3 are shown in FIG. 7, wherein (a) is the whitening coefficient, (b) is the electric conductivity, c) power factor, which is a graphical representation of the change with film thickness.

As shown in FIG. 7, as the film thickness increases, the whitening coefficient decreases, the electric conductivity increases, and the power factor calculated by the whitening coefficient and the electric conductivity increases.

Since the thermal properties of the conjugated polymer are directly related to the doping concentration, it can be seen from the above results that as the doping concentration of the conjugated polymer increases, the whitening coefficient decreases, the electrical conductivity increases, and the thermal characteristics are improved .

Table 1 shows experimental results on the thermoelectric properties of the films prepared in Example 1 and Comparative Examples 3 to 5 in order to examine the thermoelectric properties according to the coating method.

Thermoelectric film
Coating method
Doping agent
(dopants)
Whitening factor
[㎶ K ^-1 ]
Electrical conductivity
[S cm ^-1 ] Power factor
(Power factor)
[㎼ m ^-1 K ^-2 ] Example 2 Wire-Bar Coating FeCl ₃ 37.2 254 35.0 Comparative Example 4 Drop-casting FeCl ₃ 30 21 1.9 Comparative Example 5 Drop-casting FeCl ₃ 74 7 3.9 Comparative Example 6 Drop-casting NOPF ₆ 25 2.2 0.14

As shown in the above Table 1, the P3HT film prepared using the wire-bar coating method exhibited a high power factor of 35.0 ㎼ m ^-1 K ^{- 2} in Example 1, Which is significantly higher than that of Comparative Examples 4 to 6, which is a film, and exhibited improved thermal properties than the conventional technique.

From the above experimental results, it can be seen that, in the case of the P3HT film formed by the manufacturing method according to the present invention, the electrical conductivity of the doped P3HT film is increased by improving the crystallinity of the P3HT film, thereby improving the thermoelectric property of P3HT efficiently Able to know.

Claims (10)

(3-hexylthiophene) (P3HT) on a substrate to form a poly (3-hexylthiophene) film.
The coating solution according to claim 1, wherein the solvent contained in the coating solution is selected from the group consisting of Dicholrobenzene (DCB), chloroform, toluene, tetrachloroethane (TCE) and chlorobenzene Wherein the thermoelectric film is at least one selected from the group consisting of a fluorine-containing polymer and a fluorine-containing polymer.
The method of claim 1, wherein the poly (3-hexylthiophene) film further comprises dopants.
4. The method of claim 3, wherein the dopant is selected from the group consisting of FeCl ₃ , NOPF ₆ , (CF ₃ SO ₂ ) ₂ N ^- , AuCl ₃ and 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane -TCNQ). &Lt; / RTI &gt;
A thermoelectric film produced by the method of claim 1.
The thermoelectric film according to claim 5, wherein the thermoelectric film is poly (3-hexylthiophene) (P3HT).
6. The thermoelectric film according to claim 5, wherein the thermoelectric film has a thickness of 3.0 to 5.0 mu m.
A thermoelectric film of claim 5; And
And an electrode provided on the thermoelectric film.
A process for producing a poly (3-hexylthiophene) film by bar-coating a coating liquid containing poly (3-hexylthiophene) (P3HT) on a substrate,
Wherein the thermoelectric film has a thermoelectric property of 30 &lt; RTI ID = 0.0 &gt; m / m &lt; / ^RTI &gt;
10. The method of claim 9, wherein the P3HT concentration of the coating solution is 50 to 150 mg / ml.

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