KR20220021140A - Conductive polymer film and preparing method of the same - Google Patents

Abstract

The present invention relates to a conductive polymer film which includes a compound containing a first repeating unit derived from poly(3,4-ethylenedioxythiophene (PEDOT) and a second repeating unit derived from poly(4-styrenesulfonate) (PSS), and shows a percentage of the thermoelectric reliability value defined according to mathematical formula 1 of [thermoelectric reliability value= Rs/S^2] after being stored for 288 hours of 65% or more, based on the thermoelectric reliability value defined according to mathematical formula 1 after being stored (0 hr) under the conditions of a relative humidity of 95% and a temperature of 27℃. In mathematical formula 1, Rs is a sheet resistance value (ohm/sq) and S is the Seebeck coefficient value (μV/K). The conductive polymer film according to the present invention has excellent thermoelectric properties and shows high reliability under humid environment.

Description

Conductive polymer film and method of manufacturing a conductive polymer film {CONDUCTIVE POLYMER FILM AND PREPARING METHOD OF THE SAME}

It relates to a conductive polymer film and a method for manufacturing the same, and more particularly, to a conductive polymer film implementing high reliability.

Thermoelectric (TE) power generation that can directly convert waste heat into electricity is being developed as a solution to the global energy problem. In particular, organic TE materials are receiving considerable attention because of their low thermal conductivity (κ) compared to inorganic materials and their ability to control physical properties due to freedom in design. However, organic TE materials have the disadvantage of low electrical conductivity, so many researchers have focused on improving the electrical conductivity (σ). Ethylenedioxythiophene) polystyrene sulfonate (hereinafter may be referred to as “PEDOT:PSS”) is being used. In particular, excellent electrical conductivity (σ) could be achieved by post-treatment with strong acids or high boiling point solvents. However, in order to commercialize the organic TE film, reliability as well as electrical properties must be satisfied.

TE efficiency is evaluated by the figure of merit ZT = S ² σT /κ, where S, T, σ and κ are the Seebeck coefficient, absolute temperature and electrical conductivity and thermal conductivity, respectively. Power factor (PF=S ² σ) can replace ZT when it is difficult to evaluate thermal conductivity (κ) in a thin film. The TE film containing PEDOT:PSS has a problem of poor stability due to poor performance even with short exposure in a humid environment. Therefore, in order to develop a commercial TE film, it is essential to improve the humidity stability of the organic TE film.

One embodiment of the present invention provides a conductive polymer film having excellent thermoelectric properties and excellent reliability in a humid environment.

Another embodiment of the present invention is a method for producing the conductive polymer film, and provides an efficient method for producing a film capable of practically implementing the above advantages.

Another embodiment of the present invention provides a thermoelectric device including the conductive polymer film, which implements high device reliability.

In one embodiment of the present invention, a first repeating unit derived from poly (3,4-ethylenedioxythiophene) (PEDOT) and poly (4-styrenesulfonate) (Poly (4- It contains a compound containing a second repeating unit derived from styrenesulfonate, PSS), and before storage (0 hours) under conditions of 95% relative humidity and 27 ° C. To provide a conductive polymer film having a thermoelectric reliability value of 65% or more according to Equation 1 below.

In Equation 1, Rs is a sheet resistance (Ohm/sq) value, and S is a Seebeck coefficient (μV/K) value.

In another embodiment of the present invention, the first repeating unit derived from poly (3,4-ethylenedioxythiophene) (PEDOT) and poly (4-styrenesulfonate) (Poly (4- preparing a raw material solution containing a raw material compound containing a second repeating unit derived from styrenesulfonate, PSS); preparing a film precursor from the raw material solution; and heat-treating the film precursor to prepare a cured film; It provides a method for producing a conductive polymer film further comprising at least one of the following steps i) to ii).

i) mixing a glycerol solution with the raw material solution

ii) placing the film precursor in a glycerol vapor atmosphere chamber;

to provide.

In another embodiment of the present invention, a conductive polymer film; and an electrode on the conductive polymer film, wherein the conductive polymer film includes a first repeating unit derived from poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(4- Styrenesulfonate) (Poly(4-styrenesulfonate, PSS)-derived compound containing a second repeating unit is contained, and the conductive polymer film is stored under the conditions of 95% relative humidity and 27° C. (0 hours). Provided is a thermoelectric element in which a percentage of the thermoelectric reliability value according to Equation 1 after storage for 288 hours compared to the thermoelectric reliability value according to Equation 1 is 65% or more.

The conductive polymer film has excellent thermoelectric properties as well as excellent reliability in a humid environment. The method for producing the conductive polymer film may provide an efficient method for producing a conductive polymer film capable of practically realizing the above advantages. In addition, the thermoelectric element can realize high reliability by including the conductive polymer film.

1 shows the FTIR spectrum of the film of Example 2.
Figure 2 shows the FTIR spectrum of the film of Example 1.
3 is a graph showing electrical conductivity (σ, S/cm) and Seebeck coefficient (S, Seebeck Coefficient, μV/K) for each film of Comparative Examples and Examples.
4 is a graph showing the power factor (Power Factor, PF, μW/mK ² ) for each film of Comparative Examples and Examples.
5 is a graph showing the elastic modulus (GPa) measured for each film of Comparative Examples and Examples.
6 is a graph showing the normalized value (Normalized 1/S) of 1/S over time, in which the films of Comparative Examples 1 and 2 and Examples 1 and 2 were placed under a predetermined environment for measurement of humidity stability.
7 is a graph showing the normalized value of 1/Rs over time (Normalized 1/Rs) of the films of Comparative Examples 1 and 2 and Examples 1 and 2 placed under a predetermined environment for measurement of humidity stability.
8 is a graph showing 1/PF normalized values (Normalized 1/PF) over time, in which the films of Comparative Examples 1 and 2 and Examples 1 and 2 were placed under a predetermined environment for measuring humidity stability.
9 is a graph showing the PF (μW / mK ² ) value over time by placing the films of Comparative Examples 1 and 2 and Examples 1 and 2 under a predetermined environment for measuring humidity stability.
10 is a graph showing contact angles for films of Comparative Examples 1 and 2 and Examples 1 and 2;
11 is a graph showing the weight ratio of PEDOT to PSS before and after placing the films of Comparative Examples 1 and 2 and Examples 1 and 2 under a predetermined environment for measuring humidity stability.
FIG. 12 (a) shows a photograph in which two gold (Au) electrodes are deposited on each film, and FIG. 12 (b) is a schematic side view of a device having evaluated thermoelectric properties.

Advantages and features of the present invention, and a method of achieving them will become clear with reference to the following examples. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, Only the present embodiments are provided so that the disclosure of the present invention is complete, and to completely inform those of ordinary skill in the art to which the present invention belongs, the scope of the invention, the present invention is defined by the scope of the claims will only be

In order to clearly express various layers and regions in the drawings, the thicknesses are enlarged. And in the drawings, for convenience of description, the thickness of some layers and regions are exaggerated. Like reference numerals refer to like elements throughout.

In addition, in the present specification, when a part of a layer, film, region, plate, etc. is said to be “on” or “on” another part, this is not only when it is “directly on” another part, but also when there is another part in the middle. also includes Conversely, when we say that a part is "just above" another part, we mean that there is no other part in the middle. In addition, when a part of a layer, film, region, plate, etc. is said to be "under" or "under" another part, it is not only when it is "under" another part, but also when there is another part in between. include Conversely, when a part is said to be "just below" another part, it means that there is no other part in the middle.

In one embodiment according to the present invention, a first repeating unit derived from poly(3,4-ethylenedioxythiophene), PEDOT and poly(4-styrenesulfonate) (Poly(4 -styrenesulfonate, PSS)-derived compound containing a second repeating unit, and stored under the conditions of 95% relative humidity and 27 ° C. (0 hours), compared to the thermoelectric reliability value according to Equation 1, stored for 288 hours It provides a conductive polymer film, wherein the percentage of the thermoelectric reliability value according to Equation 1 after the above is 65% or more.

So far, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (hereinafter may be referred to as “PEDOT:PSS”) has achieved significant achievements in the field of organic thermoelectrics as an alternative to inorganic thermoelectrics (TE) materials. showed However, the PEDOT:PSS film has practical limitations because its performance is sensitive to humidity.

The conductive polymer film according to one embodiment is a film in which the thermoelectric reliability value according to Equation 1 is excellently maintained before and after processing under severe conditions with high humidity. It is advantageous to be applied to devices requiring high reliability with excellent thermoelectric performance. have an advantage

Thermoelectric reliability maintenance performance according to Equation 1 of the conductive polymer film according to an embodiment, humidity stability, contact angle to water, characteristics on XPS/FTIR spectrum, changes in chemical composition in a humid environment, etc. It is a component that appears by organically combining elements such as the chemical structure of the composite included in the conductive polymer film, other chemicals applied in the manufacturing process of the conductive polymer film, and process conditions such as temperature and time.

In one embodiment, the conductive polymer film contains a compound including a PEDOT-derived first repeating unit and a PSS-derived second repeating unit, and the second repeating unit may further include at least a portion of the structure of Formula 1 below. there is.

In Formula 1, n may be about 190 to about 2200. Specifically, the compound according to the structure of Formula 1 may have a cross-linked structure of the second repeating unit derived from PSS. Since the compound further includes the structure of Formula 1 in the second repeating unit, the conductive polymer film may have an improved crosslinking density, and based on this, excellent mechanical properties may be exhibited. In addition, since the conductive polymer film exhibits excellent hydrophobicity, it is possible to obtain an advantage of improving the humidity reliability of devices and the like.

The conductive polymer film according to an embodiment may have an oxygen (O1s) atomic percentage (%) derived from an X-ray photoelectron spectroscopy (XPS) spectrum of less than about 27%, for example, less than about 26%. can be, for example, less than about 25%, for example, greater than or equal to about 20%, less than about 27%, such as greater than or equal to about 20%, less than about 26%, for example, It may be greater than or equal to about 20% and less than about 25%. When the conductive polymer film satisfies the atomic percentage (%) of oxygen (O1s) on XPS within the above range, improved reliability can be imparted to a device to which the film is applied based on excellent hydrophobicity.

The contact angle of the conductive polymer film with respect to water according to one embodiment may be greater than about 31 °, for example, may be greater than about 35 °, for example, may be greater than about 40 °, for example , may be about 60 ㅀ or less. Since the contact angle of the conductive polymer film with respect to water satisfies the above range, improved long-term reliability may be realized based on excellent hydrophobicity.

The conductive polymer film according to an embodiment contains the elemental composition ratio (R1) of PEDOT to PSS before storage under the conditions of 95% relative humidity and 27° C. (0 hours) and PEDOT to PSS after storage for 288 hours under the same conditions. The PEDOT / PSS increase rate (%) according to Equation 2, calculated as the element composition ratio (R2), may be about 40% or less, for example, about 30% or less, for example, about 25% or less, and , for example, about 20% or less, for example, about 5% or more. The 'composition ratio of elements' means a ratio of the total number of elements derived from PEDOT to the total number of elements derived from PSS in the conductive polymer film.

When the PEDOT/PSS increase rate (%) according to Equation 2 satisfies the above range, the conductive polymer film can be maintained without a change in chemical structure even in a humid environment, and excellent humidity reliability can be realized.

The conductive polymer film according to an embodiment may include a Fourier-transform infrared (FTIR) spectrum at about 2500 cm ⁻¹ to about 3000 cm ⁻¹ at a first peak; a second peak at about 1100 cm ^-1 to about 1200 cm ^-1 ; and a third peak at about 1300 cm ^-1 to about 1500 cm ^-1 . The first peak may correspond to CH vibration in the structure of Chemical Formula 1, and the second peak and the third peak may correspond to vibration of the aromatic sulfonate ester group in Chemical Formula 1 above. The conductive polymer film has an FTIR spectrum in which the first peak, the second peak, and the third peak appear simultaneously, so that excellent humidity reliability can be realized based on a corresponding chemical structure.

The conductive polymer film according to an embodiment may have a ratio of 1/PF value after storage for 288 hours compared to 1/PF value before (0 hours) stored under conditions of 95% relative humidity and 27° C. of temperature is about 65% or more and may be, for example, about 70% or greater, for example, about 80% or greater. The PF corresponds to a power factor (μW/mK ² ) value of the polymer film. When the conductive polymer film exhibits such 1/PF value maintenance performance, excellent humidity reliability corresponding thereto can be realized.

In another embodiment according to the present invention, a first repeating unit derived from poly(3,4-Ethylenedioxythiophene) (PEDOT) and poly(4-styrenesulfonate) (Poly(4 Preparing a raw material solution containing a raw material compound containing a second repeating unit derived from -styrenesulfonate, PSS) preparing a film precursor from the raw material solution, and heat-treating the film precursor to prepare a cured film; Including, and further comprising at least one step of the following i) to ii), it provides a method for producing a conductive polymer film.

i) mixing a glycerol solution with the raw material solution

ii) placing the film precursor in a glycerol vapor atmosphere chamber;

The method for producing the conductive polymer film includes preparing a raw material solution containing the compound. The raw material compound in the raw material solution may have a chemical structure including a first repeating unit derived from PEDOT and a second repeating unit derived from PSS. Specifically, the raw material compound may be a compound including the first repeating unit and the second repeating unit, but the second repeating unit does not include the structure of Formula 1 above. The structure of Formula 1 is the same as described above with respect to the conductive polymer film.

In one embodiment, the viscosity of the raw material solution may be from about 10 mPa·s to about 70 mPa·s at room temperature, for example, from about 15 mPa·s to about 60 mPa·s. In one embodiment, the solid content of the raw material solution may be about 0.5 wt% to about 2.0 wt%, for example, about 0.5 wt% to about 1.5 wt%, for example, about 0.8 wt% to about 1.5% by weight, for example, from about 1.0% to about 1.3% by weight. When the viscosity and the solid content are within the above ranges, it is possible to secure the processability of uniform coating without voids in the process of coating the raw material solution in a process to be described later.

The method for preparing the conductive polymer film includes preparing a film precursor from the raw material solution. In one embodiment, the film precursor may be prepared by spin coating the raw material solution. For example, the spin coating may be performed under a rotation speed of 500 rpm to 4000 rpm and a time condition of 5 seconds to 120 seconds. By spin coating under these conditions, a film precursor can be prepared without voids with an appropriate thickness.

The method for producing the conductive polymer film includes preparing a cured film by heat-treating the film precursor. The cured film is a first repeating unit derived from poly(3,4-ethylenedioxythiophene) (Poly(3,4-Ethylenedioxythiophene), PEDOT) and poly(4-styrenesulfonate) (Poly(4-styrenesulfonate, PSS) It is a base film containing the compound containing the derived second repeating unit. By heat-treating the film precursor under appropriate conditions, a film having excellent physical properties uniformity over the entire film can be produced. The heat treatment is single-step heat treatment or multi-step heat treatment can be

In one embodiment, the step of heat-treating the film precursor to prepare a cured film may be performed by heat-treating the film precursor at 100° C. to 250° C. for 10 minutes to 60 minutes.

The method for producing the conductive polymer film further includes at least one of the following steps i) to ii).

i) mixing a glycerol solution with the raw material solution

ii) placing the film precursor in a glycerol vapor atmosphere chamber;

Conventionally, many researchers added a small amount of crosslinking agent to the PEDOT:PSS solution to ensure long-term stability of electrical conductivity (σ) for PEDOT:PSS films in a humid environment. This crosslinking agent improves stability through a chemical covalent bond with PEDOT:PSS, for example, polyethylene glycol (PEG) or polyvinyl alcohol (PVA) was used. However, in the case of PEDOT:PSS film treated with PEG, etc., there is a trade-off relationship between device performance and stability. contains problems. In addition, since the film produced by treatment with PEG contains an oxygen atom derived from an ether structure, it can bind to water molecules through hydrogen bonding, etc., thereby limiting the improvement of stability. That is, in view of the fact that the level required for the reliability of the thermoelectric device is gradually increasing, there is a difficult limitation in using PEG as a polymer crosslinking agent.

In the method of manufacturing the conductive polymer film according to an embodiment, a processing method of treating glycerol for this crosslinking reaction may be applied. Although oxygen atoms are present in the glycerol molecule as in PEG, they can be almost removed during the condensation reaction according to the above preparation method. As a result, the conductive polymer film according to an embodiment can prepare a film with high humidity stability compared to the case of PEG-treated. Specifically, glycerol imparts a predetermined cured structure to the film through a crosslinking reaction between its hydroxy group (-OH) and a sulfonic acid group (-SO ₃ H) in the raw material compound, thereby greatly improving TE reliability. can In addition, glycerol has the advantage of high eco-friendliness and recyclability compared to other technical means such as PEG.

More specifically, the glycerol may have a higher affinity for the second repeating unit derived from PSS than the first repeating unit derived from PEDOT. In glycerol, there are three hydroxyl groups (-OH) capable of hydrogen bonding and/or dipole-dipole interactions with a sulfonic acid group (-SO ₃ H). According to one embodiment, when a glycerol solution is mixed with the raw material solution or when glycerol vapor is treated on the cured film, a condensation reaction occurs between the hydroxyl group of glycerol and the sulfonic acid group of the PSS-derived second repeating unit. Bonds may be formed. As a result, sulfonic acid ester (SOC) groups are formed. Accordingly, the conductive polymer film according to an embodiment may include both a sulfonic acid group and a sulfonic acid ester group in the compound contained therein. The hydroxyl group of glycerol is removed during the crosslinking reaction, and the film shows little change in the total amount of oxygen atoms after glycerol treatment. Changes in the number of oxygen atoms in the film can have a significant impact on stability under humid conditions. For example, when an oxygen atom-containing structure such as an ether group (-O-) is increased in its chemical structure through post-treatment of a PEDOT:PSS film, hydrogen bonding with water molecules is promoted and the film's electrical conductivity in a humid environment is promoted. may cause deterioration. In contrast, in the conductive polymer film according to an exemplary embodiment, the content of oxygen atoms does not substantially change even through post-treatment, so that humidity stability can be greatly improved.

In one embodiment, the step i) is a step of mixing a glycerol solution with the raw material solution, and a film precursor is prepared by coating the raw material solution mixed with the glycerol solution, and the film precursor is heat treated to a cured film By preparing a conductive polymer film having the above advantages can be prepared.

In one embodiment, step i) may be a step of mixing 0.5% by volume to 10% by volume, for example, 0.5% by volume to 5% by volume of a glycerol solution with the raw material solution.

In another embodiment, step ii) may be performed by placing the film precursor in a chamber under a glycerol vapor atmosphere and then treating at 100° C. to 250° C. for 10 minutes to 40 minutes.

The manufacturing method may include either step i) or step ii), or both steps i) and ii) may be included.

In the method for producing the conductive polymer film, the oxygen atom increase rate (%) according to Equation 3 below may be less than about 10%, for example, less than about 9%, for example, less than about 5%. there is.

In Equation 3, AP2 is the oxygen (O1s) atomic percentage (%) value on the XPS spectrum of the conductive polymer film, and AP1 is PEDOT:PSS prepared by the manufacturing method in which neither step i) nor step ii) is included. Oxygen (O1s) atomic percentage (%) value on the XPS spectrum of the film.

Through this, the conductive polymer film manufactured by the manufacturing method according to the embodiment may have the advantage of imparting excellent humidity stability and reliability to the device to which it is applied.

In another embodiment, a conductive polymer film; and an electrode on the conductive polymer film, wherein the conductive polymer film includes a first repeating unit derived from poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(4- Styrene sulfonate) (Poly (4-styrenesulfonate, PSS) containing a compound containing a derived second repeating unit, and stored under the conditions of 95% relative humidity and temperature of 27 ° C. (0 hours) according to Equation 1 above Provided is a thermoelectric element in which a percentage of the thermoelectric reliability value according to Equation 1 after storage for 288 hours compared to the thermoelectric reliability value is 65% or more.

All matters relating to the conductive polymer film are the same as described above.

In the thermoelectric element, the electrode may include one selected from the group consisting of silver (Ag), platinum (Pt), copper (Cu), gold (Au), and combinations thereof.

The thermoelectric element can implement excellent humidity stability and long-term reliability by applying the conductive polymer film as described above.

Hereinafter, specific embodiments of the present invention are presented. However, the examples described below are only for specifically illustrating or explaining the present invention, and thus the present invention is not limited thereto.

<Examples and Comparative Examples>

Comparative Example 1

A glass substrate (25 mm × 25 mm) was cleaned by ultrasonication under distilled water and isopropyl alcohol, and then dried in a vacuum oven for 12 hours.

PEDOT: PSS solution (HC Starck GmbH, Clevios PH 1000) was mixed with 5% by volume of dimethyl sulfoxide (Dimethyl Sulfoxide, DMSO, Sigma Aldrich) to prepare a mixed solution, and the mixed solution was stirred for 30 minutes. . Then, the mixed solution was filtered through a hydrophilic filter having pores of 0.45 μm.

The washed glass substrate was treated with UV or ozone for 15 minutes, and the mixed solution was spin-coated under 2300 rpm conditions for 40 seconds to prepare a film precursor. The film precursor was heat-treated at 150° C. for 30 minutes to prepare a PEDOT:PSS film.

Comparative Example 2

2% by volume of polyethylene glycol (PEG) was mixed with the mixed solution prepared in Comparative Example 1. The washed glass substrate was treated with UV or ozone for 15 minutes, and the PEG-added mixed solution was spin-coated for 40 seconds under 2300 rpm conditions to prepare a film precursor. The film precursor was heat-treated at 150° C. for 30 minutes to prepare a PEG solution-treated PEDOT:PSS film.

Comparative Example 3

The PEDOT:PSS film of Comparative Example 1 was placed in a polyethylene glycol (PEG) vapor atmosphere chamber at a pressure of 10 ^-2 Pa at 150° C. for 15 minutes to prepare a PEG vapor-treated PEDOT:PSS film.

Example 1

2% by volume of glycerol was mixed with the mixed solution prepared in Comparative Example 1. The washed glass substrate was treated with UV or ozone for 15 minutes, and the glycerol-added mixed solution was spin-coated for 40 seconds under 2300 rpm conditions to prepare a film precursor. The film precursor was heat-treated at 150° C. for 30 minutes to prepare a conductive polymer film.

Example 2

The film precursor prepared in Comparative Example 1 was placed in a glycerol vapor atmosphere chamber at a pressure of 10 ⁻² Pa at 150° C. for 15 minutes to prepare a conductive polymer film.

<Evaluation>

Experimental Example 1: Measurement of Film Thickness

The thickness of each film in Examples and Comparative Examples was obtained using an alpha-step profilometer (Dektak Stylus Profilometer, Bruker, Billerica, MA, USA).

Experimental Example 2: Measurement of the elastic modulus of the film

The modulus of elasticity of each of the films of Examples and Comparative Examples was obtained by measuring eight different positions on the film using an AFM (Atomic Force Microscopy, Bruker, Billerica, MA, USA) nanoindentation tip (NICT-MTAP). Specifically, it was measured in AFM tapping mode. 5 and Table 4 below show the elastic modulus (GPa) measured for the films of Comparative Examples and Examples, respectively.

Modulus of elasticity (GPa) In-plane thermal conductivity (W/mK) ZT (@300K) Comparative Example 1 3.2 - Comparative Example 2 5.3 1.42 0.74 ㅧ 10 ^-2 Comparative Example 3 3.3 1.12 1.14 ㅧ 10 ^-2 Example 1 3.4 1.13 1.02 ㅧ 10 ^-2 Example 2 3.8 1.20 1.15 ㅧ 10 ^-2

Referring to Table 1, compared to the film of Comparative Example 1, which is a PEDOT:PSS film in which the solution/steam is not treated, the solution/steam treatment of polyethylene glycol (PEG) or glycerol in Comparative Examples 2-3 and the above Examples Examples 1 and 2 It can be seen that the elastic modulus of the films is improved, which may be possible by cross-linking PEG or glycerol with the polymer of the PEDOT:PSS film.

In the case of the PEG solution-treated film as in Comparative Example 2, it exhibits a higher modulus of elasticity compared to the films of Examples 1 and 2, which is due to the relatively high molecular weight of PEG, and as a result, a dimension indicating TE efficiency. It can be understood as disadvantageous in terms of figure of merit ZT = S ² σT /κ without . Specifically, the electron contribution to the thermal conductivity (κe = LσT, where L is the Lorenz number of 2.44 X 10 ^-8 W/ΩK ² ) for each of the films of Examples and Comparative Examples is similar. At this time, the in-plane thermal conductivity (κ, W/mK) of the films of Comparative Examples 2 to 3 and Examples 1 to 2 is as described in Table 4, and at this time, the ZT value at 300K is also approximately as described in Table 4 same.

Referring to Table 1, the film of Comparative Example 2 treated with PEG under the same treatment conditions as solution treatment showed a higher in-plane thermal conductivity value than the film of Example 1 treated with glycerol. On the other hand, under the same treatment conditions of steam treatment, the PEG-treated film of Comparative Example 3 exhibited lower in-plane thermal conductivity than the glycerol-treated film of Example 2. As a result, the ZT of the film of Example 1 treated with glycerol solution was higher than the ZT of the film of Comparative Example 2 treated with PEG solution, and the film of Example 2 treated with glycerol vapor showed the highest ZT value. It was confirmed that glycerol is more advantageous than PEG in terms of device efficiency. Comprehensively, since the films of Examples 1 and 2 exhibit a relatively high modulus of elasticity in addition to the reliability aspect to be described later, it can be confirmed that they implement superior performance than the films of Comparative Examples 2 and 3.

Experimental Example 3: Measurement of the FTIR spectrum of the film

Fourier-transform infrared (FTIR) spectra of each film were recorded with a FerkinElmer Frontier FT-NIR/MIR spectrometer (PerkinElmer Inc., Waltham, MA, USA).

1 shows the FTIR spectrum of the film of Example 2. In order to analyze the FTIR spectrum of Example 2 in detail, the FTIR spectrum of pure poly(4-styrenesulfonate (PSS) and glycerol) was shown together.

In the case of the film of Example 2, compared with the PSS spectrum, a new peak appeared at 2782 cm ^-1 , which corresponds to the CH vibration of PSS chemically modified by glycerol vapor. Also, two peaks occurred at 1176 cm ^-1 and 1350 cm ^-1 , which are consistent with the vibration of the aromatic sulfonate ester group (SO). This change demonstrates the formation of a covalent bond between the sulfonic acid group (-SO ₃ H) and the hydroxyl group (-OH). It can be seen that glycerol vapor is deposited on the PSS film and the sulfonic acid of PSS and the hydroxyl group of glycerol react.

In addition, Figure 2 shows the FTIR spectrum of the film of Example 1. In order to analyze the FTIR spectrum of Example 1 in detail, the FTIR spectrum of the pure PSS was also shown. A peak at 1352 cm ^-1 newly appeared in the film of Example 1 indicates the presence of an aromatic sulfonate ester group (SO).

Experimental Example 4: Measurement of the XPS spectrum of the film

X-ray photoelectron spectroscopy (XPS) spectra of each film were obtained from 5 different samples for each film using a SIGMA PROBE model (Thermo VG Scientific, East Grinstead, UK).

As shown in Table 2 below, the oxygen (O1s) atomic percentage (%) of the polyethylene glycol (PEG) solution-treated film of Comparative Example 2 and the polyethylene glycol (PEG) vapor-treated film of Comparative Example 3 was PEDOT of Comparative Example 1 : Higher than the atomic percentage (%) of the PSS film. However, in the case of the glycerol solution-treated film of Example 1 and the glycerol vapor-treated film of Example 2, it can be confirmed that there is no significant change compared to the oxygen (O1s) atomic percentage (%) of the PEDOT:PSS film of Comparative Example 1 In particular, in the case of the glycerol vapor-treated film of Example 2, it was confirmed that there was substantially no change compared to the oxygen atom percentage (%) of the PEDOT:PSS film of Comparative Example 1. Oxygen atoms in the film are disadvantageous in terms of humidity stability because they induce water molecules by hydrogen bonding or the like under humid conditions. From this point of view, it was confirmed that the glycerol solution/steam-treated film was advantageous in improving humidity stability compared to the polyethylene glycol (PEG) solution/steam-treated film.

Referring to Table 2 below, the oxygen (O1s) atomic percentage (%) derived from the XPS spectrum of the conductive polymer film according to an embodiment may be less than about 27%, for example, it may be less than about 26% and , for example, less than about 25%, for example, greater than or equal to about 20%, less than about 27%, such as greater than or equal to about 20%, less than about 26%, such as about 20 % or more, but less than about 25%.

O1s Atomic Percentage (%) Comparative Example 1 23,27 Comparative Example 2 27,95 Comparative Example 3 27.36 Example 1 25.27 Example 2 24.05

Referring to Table 3 below, in the case of the conductive polymer film prepared by the method for preparing the conductive polymer film according to one embodiment, the oxygen atom increase rate (%) calculated by Equation 3 during the manufacturing process is about 10% It can be less than, for example, less than about 9%, for example, less than about 5%. Through this, it was confirmed that the conductive polymer film prepared by the manufacturing method according to the embodiment has the advantage of imparting excellent humidity stability and reliability to the device to which it is applied.

In Equation 3, AP2 is the oxygen (O1s) atomic percentage (%) value on the XPS spectrum of the film after solution/steam treatment, and AP1 is the oxygen (O1s) atomic percentage (%) on the XPS spectrum of the film before solution/steam treatment (%) is the value

Comparative Example 1 is a film before solution/steam treatment in preparing the films of Comparative Examples 2 to 3 and Examples 1 to 2, and the films of Comparative Examples 2 to 3 and Examples 1 to 2 are each predetermined Corresponds to film after solution/steam treatment.

Oxygen atom increase rate (%) Comparative Example 1 - Comparative Example 2 20.11 Comparative Example 3 17.58 Example 1 8.59 Example 2 3.35

Experimental Example 5: Measurement of the contact angle of the film

The contact angle with respect to water on each film was measured using a contact angle analyzer (Suwon-si, Surface Electro-optical (Penix-10)). The contact angles of the three films were obtained by measuring four different positions.

10 and Table 4 are graphs and tables showing contact angles for the films of Comparative Examples 1 and 2 and Examples 1 and 2;

Contact angle (@water, ㅀ) Comparative Example 1 30.1 Comparative Example 2 30.6 Example 1 31.2 Example 2 41.5

The conductive polymer film according to an embodiment may have a contact angle with respect to water of greater than about 31°, for example, greater than about 35°, for example, greater than about 40°.

10 and Table 4, the glycerol-treated films of Examples 1 and 2 have a higher contact angle than the untreated PEDOT:PSS film of Comparative 1 above. This means that the films of Examples 1 and 2 show hydrophobicity, which can be seen to mean that they exhibit a higher crosslinking density. In addition, the films of Examples 1 and 2 exhibit a higher contact angle compared to the film of Comparative Example 2 treated with PEG solution. That is, it can be seen that the glycerol-treated film exhibits higher crosslinking density and hydrophobicity compared to the PEG-treated film. This shows that the films of Examples 1 and 2 are advantageous in terms of humidity reliability and elasticity compared to the films of Comparative Example 2. In the case of Examples 1 and 2, it can be seen that the glycerol vapor-treated film of Example 2 exhibits improved humidity reliability and elastic modulus than the film of Example 1 treated with glycerol solution.

Experimental Example 6: Evaluation of thermoelectric properties

A gold (Au) electrode having a thickness of 70 nm was thermally-deposited on each film using a shadow mask under a pressure of 10 ⁻⁴ Pa. FIG. 12 (a) shows a photograph in which two gold (Au) electrodes 10 are deposited on each film 20 , and FIG. 12 ( b ) is a schematic diagram of a device that has been evaluated for thermoelectric properties. A side view is shown. Referring to FIG. 12 , the length L and width W of each of the two gold electrodes 10 were 17 mm and 8 mm, and the distance d between the two electrodes was manufactured to be 2 mm. Then, two K-type thermocouples (Extech, EA15, Taipei, Taiwan) and a current-voltage (IV) probe 30 were respectively attached to the gold electrode 10 at the same distance (10 mm interval).

S was calculated from the equation S = ΔV/ΔT, where ΔV and ΔT are the voltage difference and temperature difference between the hot and cold side of the film, respectively. ΔV and ΔT were measured using an Agilent 3458A digital multimeter (Agilent Technologies Inc., Santa Clara, CA, input impedance >10 GΩ) and Extech EA15, respectively. All instruments were connected to a computer and controlled by LabView software (version 2017, National Instruments, Austin, TX, USA). To check the accuracy of the measurement setup, the absolute Seebeck coefficient of pure nickel foil was measured and a reasonable value of -20.2±0.4 μV/K was obtained. The thermal conductivity (κ) of each film was calculated using the relationship that κ is proportional to the square root of the modulus of elasticity. The reported value for the in-plane thermal conductivity (κ) of the film of Comparative Example 1 was 1.10 W/mK. The sheet resistance (Rs) was obtained from a four-point probe system to calculate σ, based on the equation σ = 1/(Rs t). where t is the thickness of the film.

3 is a graph showing electrical conductivity (σ, S/cm) and Seebeck coefficient (S, Seebeck Coefficient, μV/K) for each of the films of Comparative Examples and Examples. 3, as in Comparative Example 2, the polyethylene glycol (PEG) solution-treated film exhibited the lowest electrical conductivity (σ), and the Seebeck coefficient of the glycerol vapor-treated film as in Example 2 (S) showed the highest value.

4 is a graph showing the power factor (Power Factor, PF, μW/mK ² ) for each of the films of Comparative Examples and Examples. Referring to FIG. 4 , it can be seen that the PF of the glycerol-treated film is higher than the PF of the polyethylene glycol (PEG)-treated film under the same treatment process during solution treatment or steam treatment. In addition, as in Example 2, it was confirmed that the glycerol vapor-treated film exhibited the highest PF value.

Experimental Example 7: Humidity stability evaluation

A chamber made of an acrylic plate and having a width x length x height of 300 mm x 300 mm x 300 mm was prepared, and a humidifier was provided to control the relative humidity inside the chamber. For the films of Examples 1 and 2 and Comparative Examples 1 and 2, the Seebeck coefficient (S, Seebeck Coefficient, μV/K) before placing each film in the chamber under the conditions of 95% relative humidity and 27° C. Values and sheet resistance (Rs, Ohm/sq) values were measured, and S and Rs of each film were measured 288 hours after being placed in the chamber. For accurate evaluation of humidity stability, the S and Rs values of the films placed in the chamber for different times were normalized to the initial value (0h). Based on the S and Rs values of each film, the thermoelectric reliability values of the films according to Equation 1 after the initial (0 hours) and 288 hours have elapsed were obtained. In addition, the percentage of the thermoelectric reliability value after 288 hours of treatment compared to the initial thermoelectric reliability value for each film was also calculated. The results are shown in Table 5 below.

Comparative Example 1 Comparative Example 2 Example 1 Example 2 0 hours S 20.22 18.66 18.80 20.90 Rs 55.64 72.96 65.60 63.04 288 hours S 40.33 34.60 31.39 32.21 Rs 134.23 150.90 136.49 125.08 Thermoelectric Reliability (Rs/S ² ) 0 hours 0.136 0.210 0.186 0.144 288 hours 0.083 0.126 0.139 0.121 percentage(%) 60.64% 60.16% 74.63% 83.54%

Referring to Table 5, the conductive polymer film according to an embodiment was stored for 288 hours compared to the thermoelectric reliability value according to Equation 1 before storage (0 hours) under the conditions of 95% relative humidity and 27° C. The percentage of the thermoelectric reliability value according to Equation 1 after the completion of the operation may be about 65% or more, for example, about 70% or more, for example, about 74% or more, for example, about 80% or more. In the case of the films of Examples 1 and 2, compared to the films of Comparative Examples 1 and 2, it can be seen that the retention of thermoelectric reliability is greatly improved under humid harsh conditions of 95% relative humidity and 27 ° C. .

6 is a graph showing the normalized value (Normalized 1/S) of 1/S with respect to time after placing the films of Comparative Examples 1 and 2 and Examples 1 and 2 in the chamber. Referring to FIG. 6 , it can be seen that the normalized value of 1/S of the films of Comparative Examples 1 and 2 and Examples 1 and 2 with time hardly changes within an error range of about 15%. 7 is a graph showing the normalized value of 1/Rs (Normalized 1/Rs) with time after placing the films of Comparative Examples 1 and 2 and Examples 1 and 2 in the chamber. Referring to FIG. 7 , it can be seen that the normalized value of 1/Rs of the film decreases as the chamber storage time increases, unlike the normalized value of 1/S. 6 and 7, the glycerol solution/steam-treated film of Examples 1 and 2 has higher 1/S and 1/Rs values compared to the PEG solution-treated film of Comparative Example 2 This can be seen as suggesting that the films of Examples 1 and 2 are more positive than the films of Comparative Example 2 in improving the performance of the thermoelectric element.

The conductive polymer film according to one embodiment has a ratio of 1/PF value after storage for 288 hours compared to 1/PF value before (0 hours) stored under conditions of 95% relative humidity and 27° C. of temperature is about 65% or more, For example, it can be about 70% or more, such as about 80% or more.

8 and 9 show 1/PF normalized values (Normalized 1/PF) and PF (μW/mK) over time after placing the films of Comparative Examples 1 and 2 and Examples 1 and 2 in the chamber, respectively. ² ) It is a graph showing the values. Referring to FIG. 8, the 1/PF value of the film of Example 1 treated with the glycerol solution was 75% of the 1/PF value after 288 hours storage in the chamber compared to the value before storage in the chamber. , in the case of the film of Example 2 treated with glycerol vapor, it was confirmed that it exhibited higher reliability as 82%. On the other hand, in the case of the PEG solution-treated film of Comparative Example 2, the same calculated value was only 57%.

The conductive polymer film according to one embodiment has an elemental composition ratio ( The PEDOT / PSS increase rate (%) by Equation 2 of R1) may be about 40% or less, for example, about 30% or less, for example, about 25% or less, for example, It may be about 20% or less.

Atomic composition ratio of PEDOT to PSS PEDOT/PSS
Increase (%) 0 hours 288 hours Comparative Example 1 0.45 0.85 88.89 Comparative Example 2 0.51 0.72 41.18 Example 1 0.51 0.61 19.61 Example 2 0.53 0.62 16.98

In a film comprising a complex of PEDOT and PSS, PSS is a hygroscopic component and is converted into a different chemical composition through hydrogen bonding with water molecules in a humid environment. That is, the content of PSS is decreased after treatment in a humid environment compared to before treatment, and the value of PEDOT versus PSS is increased.

11 and Table 6, the films of Examples 1 and 2 treated with glycerol solution/steam showed a PEDOT/PSS increase rate of less than 20% before and after treatment under a humid environment, and the PEDOT/PSS increase rate was It can be confirmed that the PEG solution treatment film of Comparative Example 2, which exceeds 40%, exhibits excellent humidity stability. That is, in the case of the glycerol-treated films as in Examples 1 and 2, in particular, the glycerol vapor-treated films as in Example 2, may have enhanced hydrophobicity according to the glycerol treatment, and do not change with respect to water molecules By maintaining the chemical composition of PEDOT versus PSS, excellent reliability and stability can be imparted to the thermoelectric device to which the conductive polymer film is applied.

As described above, the conductive polymer film according to an exemplary embodiment has excellent thermoelectric properties as well as excellent reliability in a humid environment. The method for producing the conductive polymer film may provide an efficient method for producing a conductive polymer film capable of practically realizing the above advantages. In addition, since the thermoelectric device includes the conductive polymer film, high device reliability, particularly, excellent humidity stability may be realized.

10: electrode
20: film
30: IV probe
L: length of electrode
W: width of electrode
d: distance between electrodes

Claims (13)

A first repeating unit derived from poly(3,4-ethylenedioxythiophene) (PEDOT) and a second repeat derived from poly(4-styrenesulfonate, PSS) contains a compound comprising units,
The percentage of the thermoelectric reliability value according to the following Equation 1 after storage for 288 hours compared to the thermoelectric reliability value according to Equation 1 before storage under the conditions of 95% relative humidity and 27 ° C. (0 hours) is 65% or more,
Conductive polymer film:
[Equation 1]

In Equation 1, Rs is a sheet resistance (Ohm/sq) value, and S is a Seebeck coefficient (μV/K) value.
According to claim 1,
At least in part of the second repeating unit comprising the structure of Formula 1 below,
Conductive polymer film:
[Formula 1]

According to claim 1,
wherein the atomic percentage of oxygen (O1s) derived from the X-ray photoelectron spectroscopy (XPS) spectrum is less than 27%;
Conductive polymer film.
According to claim 1,
with a contact angle of more than 31° to water;
Conductive polymer film.
According to claim 1,
The following formula calculated as the elemental composition ratio (R2) of PEDOT to PSS after storage for 288 hours under the same conditions as the elemental composition ratio (R1) of PEDOT to PSS before storage under the conditions of 95% relative humidity and 27°C (0 hours) PEDOT / PSS increase rate (%) by 2 is 40% or less,
Conductive polymer film:
[Equation 2]
PEDOT/PSS increase rate (%) = (R2-R1)/R1 × 100
According to claim 1,
a first peak at 2500 cm ⁻¹ to 3000 cm ⁻¹ on a Fourier-transform infrared (FTIR) spectrum; 2nd peak at 1100cm ^-1 to 1200cm ^-1 ; and a third peak at 1300 cm ^-1 to 1500 cm ^-1 ,
Conductive polymer film.
According to claim 1,
The percentage of 1/PF value after storage for 288 hours compared to 1/PF value before storage (0 hours) under the conditions of 95% relative humidity and 27°C is about 65% or more,
The PF is a power factor (μW / mK ² ) value,
Conductive polymer film.
A first repeating unit derived from poly(3,4-ethylenedioxythiophene) (PEDOT) and a second repeat derived from poly(4-styrenesulfonate, PSS) preparing a raw material solution containing a raw material compound including units;
preparing a film precursor from the raw material solution; and
Including; heat-treating the film precursor to prepare a cured film;
Further comprising the step of at least one of the following i) to ii),
Method for producing conductive polymer film:
i) mixing a glycerol solution with the raw material solution
ii) placing the film precursor in a glycerol vapor atmosphere chamber;
9. The method of claim 8,
The step of preparing a cured film by heat-treating the film precursor,
carried out by heat-treating the film precursor at 100° C. to 250° C. for 10 minutes to 60 minutes,
Method for producing a conductive polymer film.
9. The method of claim 8,
The step i) is a step of mixing a glycerol (Glycerol) solution of 0.5% by volume to 10% by volume with the raw material solution, the method for producing a conductive polymer film.
9. The method of claim 8,
Step ii) is performed by placing the cured film in a chamber under a glycerol vapor atmosphere and then treating at 100° C. to 250° C. for 10 minutes to 40 minutes,
Method for producing a conductive polymer film.
9. The method of claim 8,
The oxygen atom increase rate (%) according to the following Equation 3 is less than 10%,
Method for producing conductive polymer film:
[Equation 3]
Oxygen atom increase rate (%) = (AP2 - AP1)/AP1 X 100
In Equation 3, AP2 is the oxygen (O1s) atomic percentage (%) value on the XPS spectrum of the conductive polymer film, and AP1 is the XPS of the cured film prepared by not including steps i) and ii). Oxygen (O1s) atomic percentage (%) value on the spectrum.
conductive polymer film; and
including an electrode on the conductive polymer film,
The conductive polymer film includes a first repeating unit derived from poly(3,4-ethylenedioxythiophene) (Poly(3,4-Ethylenedioxythiophene), PEDOT) and poly(4-styrenesulfonate) (Poly(4-styrenesulfonate, PSS) containing a compound comprising a second repeating unit derived from,
The percentage of the thermoelectric reliability value according to the following Equation 1 after storage for 288 hours compared to the thermoelectric reliability value according to the following Equation 1 before storage under the conditions of 95% relative humidity and 27° C. of the conductive polymer film (0 hours) 65% or more;
Thermoelectric element:
[Equation 1]

In Equation 1, Rs is a sheet resistance (Ohm/sq) value, and S is a Seebeck coefficient (μV/K) value.

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