KR101147221B1 - Polythiophene based polymer nano material and method for controlling the properties of photoluminesence and conductivity of the same - Google Patents

Abstract

Provided are a polythiophene-based polymer nanomaterial and a method for controlling optical properties thereof. Polythiophene-based polymer nanomaterial according to the present invention is obtained by electrical polymerization of at least one monomer selected from the group consisting of thiophene, 3-methyl thiophene, 3-hexyl thiophene and 3-octyl thiophene, diameter 150 It is characterized by the maximum emission peak at ～ 250nm, 7 ~ 30㎛, 480 ~ 560nm, and excellent workability, optical and field emission characteristics, so light emitting devices, field emission devices, solar cells, etc. It can be used in optoelectronic devices.

Description

Polythiophene based polymer nano material and method for controlling the properties of photoluminesence and conductivity of the same

The present invention relates to a polythiophene-based polymer nanomaterial and a method of controlling the light emission characteristics thereof, and more particularly, to a polythiophene-based polymer nanomaterial and a method of controlling the optical properties excellent in the light emission characteristics and having a field emission effect. It is about.

Since the π-conjugated polymer has the mechanical properties of the polymer and transitions from the insulator to the semiconductor or the conductor through chemical doping, the π-conjugated polymer can be applied to electrical, electronic, and optical devices. Recently, conductive polymers have been applied in real life and high-tech industries such as secondary batteries, antistatic, switching devices, nonlinear devices, capacitors, optical recording materials, and electromagnetic shielding materials. In order for the π-conjugated polymer to have conductivity, a doping process is required. Typically, this process is to produce the polymer in the form of a non-conductive powder or film, and then doping them (chemically) or mixing the non-conductive powder and dopant (dopant) of the polymer is dissolved in an organic solvent to have a conductivity By the method.

Synthesis methods of the conductive π-conjugated polymers include chemical polymerization, electrochemical polymerization, and chemical vapor deposition (CVD). Among them, the chemical polymerization method is the most widely used method, and mass production of polymers is possible. In addition, the polymer polymerized by the chemical method is dissolved in a solvent again to prepare a sample by a thin film or spin casting method, and the electrical properties can be controlled through the chemical doping method. The electrochemical polymerization method is a method in which monomers in an electrolyte solution form a radical in an electric field and move to one electrode to polymerize, thereby forming a relatively thin film on the surface of the sample. Many studies have been conducted for comparison. The CVD method is a recent method in which a polymer is polymerized by depositing a monomer on a basic sample at high vacuum. So far, the π-conjugated polymers polymerized in this way have very different electrical properties depending on the type of solvent or dopant used (electric conductivity: 10 ^-12 to 10 ² S / cm). have.

However, since the conductive polymer prepared by the general polymerization method is in the form of a bulk, there is a limit to the application to electric and electronic nano devices that are becoming finer. Thus, there is a need to manufacture conductive polymers into nano-sized tubes or wires.

Currently, one of the fields where many researches are recently conducted as nanomaterials is carbon nanotubes (CNT). Carbon nanotubes are superior to any other materials in terms of mechanical, electrical and chemical properties, and are well suited for electrical and electronic device characteristics in terms of their size. Therefore, the use of memory devices, field emission display (FED), etc. are being actively studied. However, carbon nanotubes must be maintained at a high temperature in the manufacturing process, and the growth and purification of nanotubes is very complicated and expensive. In addition, depending on whether the nanotube is a single-wall tube or a multi-wall tube, there are differences in physical and chemical properties, and it is very difficult to control the diameter and electrical properties of the nanotube, There is a problem of being poor.

In addition, Korean Patent Publication No. 484317 discloses π-conjugated polymer nanotubes, nanowires, and a method of manufacturing the same. However, polypyrrole or polyaniline has a narrow bandgap, and thus has no photoelectric properties, and luminescence in visible light is also observed. There is a limit that can not be applied to the optoelectronic device or the light emitting device.

Therefore, the first technical problem to be achieved by the present invention is to have a nano-size and can be applied to fine electronic devices, and at the same time unlike the conventional carbon nanotubes, the manufacturing process is easy and the light emission characteristics can be easily adjusted, and excellent processability, In particular, it is to provide a polythiophene-based polymer nanomaterial that can be applied to optoelectronic devices and light emitting devices.

The second technical problem to be achieved by the present invention is to provide a method for controlling the optical properties of the polythiophene-based polymer nanomaterial.

The present invention to achieve the first technical problem,

Obtained by the electrical polymerization of at least one monomer selected from the group consisting of thiophene, 3-methyl thiophene, 3-hexyl thiophene and 3-octyl thiophene, 150-250 nm in diameter, 7-30 μm in length, 480 It provides a polythiophene-based polymer nanomaterial characterized in that the maximum light emission peak at ~ 560nm.

According to one embodiment of the invention, the polymeric nanomaterial is tetrabutylammonium hexafluorophosphate (TBAPF ₆ ), 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF ₆ ), p-dodecylbenzene It may be doped with one or more dopants selected from the group consisting of sulfonic acid (DBSA), tetrabutylammonium tetrafluoroborate (TBABF ₄ ), and tetrabutylammonium trifluoromethanesulfonate (TBACF ₃ SO ₃ ).

According to another embodiment of the present invention, the nanomaterial may be a nanotube or a nanowire.

According to another embodiment of the present invention, the nanomaterial is a poly (3-hexylthiophene) nanowire doped with 1-butyl-3-methylimidazolium hexafluorophosphate and has a conductivity of 8 x 10 ^-3 S. It may be more than / cm.

According to another embodiment of the present invention, the nanomaterial is a poly (3-methylthiophene) nanotube doped with tetrabutylammonium hexafluorophosphate, turned on at 6V / μm, and 0.7mA at 12V / μm or more A current of more than / cm ² may flow to show the field emission effect.

The present invention to achieve the second technical problem,

(a) preparing an electrochemical polymerization solution by adding and stirring at least one monomer and a dopant selected from the group consisting of thiophene, 3-methyl thiophene, 3-hexyl thiophene, and 3-octyl thiophene to the polar solvent;

(b) depositing a metal on one side of the alumina template with nano pores and then attaching it to a stainless electrode;

(c) surrounding the alumina template with silicon tape to prevent a stainless electrode from contacting the polymerization solution;

(d) immersing the prepared electrode and another stainless electrode in the polymerization solution at regular intervals;

(e) applying a current between both electrodes to electrically polymerize the monomer in the polymerization solution into the nanomaterial in the pores of the alumina template; And

(f) removing the only alumina template into which the nanomaterial is inserted using NaOH and simultaneously de-doping or removing the alumina template using HF aqueous solution and then de-doping to control the luminescence properties. Provided is a method of controlling light emission characteristics of an opene-based polymer nanomaterial.

According to an embodiment of the present invention, the polar solvent may be any one selected from the group consisting of H ₂ O, acetonitrile, and N-methyl pyrrolidinone.

Further, the dopant is tetrabutylammonium hexafluorophosphate (TBAPF ₆ ), 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF ₆ ), p-dodecylbenzenesulfonic acid (DBSA), tetrabutylammonium Tetrafluoroborate (TBABF ₄ ), tetrabutylammonium trifluoromethanesulfonate (TBACF ₃ SO ₃ ) It can be any one selected from the group consisting of.

In addition, the metal may be any one selected from the group consisting of gold, silver, platinum, stainless steel, ITO or a composite thereof.

According to a preferred embodiment of the present invention, the step of adjusting the luminescence properties may be to increase the luminescence intensity by immersing the alumina template in aqueous NaOH solution and to red transition the maximum emission peak.

Hereinafter, the present invention will be described in more detail.

Polythiophene-based polymer nanomaterials according to the present invention has a nano-size and can be applied to fine electronic devices, and at the same time, unlike conventional carbon nanotubes, the manufacturing process is easy and light emission characteristics can be easily adjusted. Since the polythiophene-based polymer shows luminescence increase that was not observed, it can be applied to nano photoelectric devices and light emitting devices.

Polythiophene-based polymer nanomaterial according to the present invention has a nanotube or nanowire form, the length and diameter of the nanomaterial depends on the length and diameter of the nano pores of the alumina template, the reaction time, applied current, etc. Adjustable by The diameter and length of the nanomaterial are not particularly limited, but may be 150 to 250 nm in diameter and 7 to 30 μm in length. The polythiophene-based polymer nanomaterial according to the present invention is characterized in that the luminescence intensity is greater than that of the bulk polythiophene-based polymer, and the maximum luminescence peak appears at 480 to 560 nm.

In addition, the polythiophene-based polymer nanomaterial according to the present invention is a poly (3-methylthiophene) nanotubes doped with p-dodecylbenzenesulfonic acid, turned on at 6V / ㎛, 0.7 at 12V / ㎛ or more The current flow of more than mA / cm ² shows the field emission effect, which is a feature not seen in the existing bulk polythiophene polymer.

The monomer used in the preparation of the polythiophene-based polymer nanomaterial according to the present invention is shown in the following formula (1), the dopant is shown in the following formula (2).

Preparation of the polythiophene-based polymer nanomaterial according to the present invention is suitable for the thiophene-based organic monomer having a π-conjugated structure in various polar solvents (H ₂ O, acetonitrile, N-methyl-2-pyrrolidinone, etc.) Mix with dopant to make a well dispersed solution, deposit or attach metal electrodes (gold, silver, platinum, ITO, etc.) on one side of nanometer-sized porous material, and then between the electrodes in the prepared polymerization solution The polythiophene-based polymer nanomaterial or nanowire is synthesized by an electrochemical polymerization method while maintaining a proper distance. Polythiophene-based polymers in the form of nanotubes or nanowires prepared by the present invention are polythiophene, poly (3-methylthiophene) (P3MT), poly (3-hexylthiophene) (P3HT), poly (3 Octylthiophene) (P3OT).

In the process of making the polymerization solution, the state of the polymerization solution (temperature, pressure, monomer and monomer type and molar ratio) affects the production of nanotubes and nanowires. Various nanotubes and nanowires can be synthesized according to the state of the polymerization solution and the synthesis conditions during the electropolymerization. If the polymerization time is short at the applied voltage, the nanotubes are formed, and if the polymerization time is prolonged, The wire is created. Copolymers or terpolymers may be prepared by mixing two or three monomers used in the present invention and polymerizing them. In particular, the diameter of the nanotubes and the nanowires can be adjusted by controlling the nano-size of the porous material used in the present invention, and the smaller the diameter, the conductivity is improved, so that the conductivity can be appropriately controlled. In addition, it is possible to control the electrical properties of the nanomaterials to the insulator, semiconductor, conductor by the doping by the use of the dopant and the subsequent de-doping, and the optical properties can be adjusted, so the field of application is extensive.

Method for controlling the light emission characteristics of the polythiophene-based polymer nanomaterial according to the present invention is (a) at least one selected from the group consisting of thiophene, 3-methyl thiophene, 3-hexyl thiophene and 3-octyl thiophene in the polar solvent Adding an monomer and a dopant and stirring to prepare an electrochemical polymerization solution; (b) depositing a metal on one side of the alumina template with nano pores and then attaching it to a stainless electrode; (c) surrounding the alumina template with silicon tape to prevent a stainless electrode from contacting the polymerization solution; (d) immersing the prepared electrode and another stainless electrode in the polymerization solution at regular intervals; (e) applying a current between both electrodes to electrically polymerize the monomer in the polymerization solution into the nanomaterial in the pores of the alumina template; And (f) removing only the alumina template into which the nanomaterial is inserted by using NaOH and simultaneously de-doping, or by removing by using HF aqueous solution and then de-doping to control the luminescence properties.

Since the polythiophene-based polymer nanomaterial prepared according to the present invention is synthesized inside the porous material, the porous material should be removed in order to obtain a pure polythiophene-based polymer nanomaterial, which is partially dedoped by dissolving in NaOH solution. Dedoping) polythiophene-based polymer nanomaterial or nanowire sample can be obtained. In this case, as will be described later, the light emission intensity is increased than that of the conventional bulk polythiophene-based polymer, and the phenomenon that the maximum light emission peak becomes a red transition according to the degree of dedoping occurs. Therefore, the color of light emission can be changed by adjusting the degree of doping and dedoping as needed.

On the other hand, in order to obtain a doped polythiophene-based polymer nanomaterial, it is preferable to remove the alumina template by immersion in HF aqueous solution. Thus, when the alumina template is improved by HF aqueous solution, a nanomaterial having improved conductivity can be obtained, and in particular, poly (3-hexylthiophene) nano doped with 1-butyl-3-methylimidazolium hexafluorophosphate. In the case of lines, the conductivity can be ensured up to 8 x 10 ^-3 S / cm or more.

As described above, since the polythiophene-based polymer nanomaterial according to the present invention has excellent processability and shows excellent optical and field emission characteristics, the polythiophene-based polymer nanomaterial can be used in light emitting devices, field emission devices, as well as photoelectric devices such as solar cells. According to the optical property control method of the polythiophene-based polymer nanomaterial according to the present invention, there is an advantage that the optical properties of the nanomaterial can be easily adjusted as necessary.

1 is a SEM photograph of a polythiophene nanotube prepared according to Example 1. FIG.
FIG. 2 is a SEM photograph of poly (3-methylthiophene) nanotubes prepared according to Example 2. FIG.
3 is a SEM photograph of the poly (3-methylthiophene) nanowires prepared according to Example 3. FIG.
4 is a SEM photograph of the poly (3-hexylthiophene) nanowires prepared according to Example 4. FIG.
5 is a TEM photograph of poly (3-hexylthiophene) nanowires prepared according to Example 4. FIG.
6 is a TEM photograph of a strand of poly (3-hexylthiophene) nanowires prepared according to Example 4. FIG.
FIG. 7 is a SEM photograph of poly (3-octylthiophene) nanowires prepared according to Example 5. FIG.
FIG. 8 shows UV / Vis absorption spectra and emission spectra of P3MT nanotubes prepared by removing alumina templates using aqueous HF solution in Example 2. FIG.
FIG. 9 shows luminescence spectra for P3MT nanotubes prepared by removing alumina templates using HF aqueous solution and NaOH aqueous solution in Example 2. FIG.
FIG. 10 shows changes in emission spectra of P3MT nanotubes prepared according to Example 6, in which alumina template was removed using an aqueous HF solution, and samples dedoped using cyclovoltametry. One result.
FIG. 11 is a result of measuring absorption spectra and emission spectra under a chloroform solvent with respect to the P3MT nanotube prepared according to Example 3, in which the alumina template was removed using HF aqueous solution and the sample removed using NaOH aqueous solution.
FIG. 12 is a P3HT nanowire prepared in Example 4, where absorption spectra and emission spectra were measured for samples from which an alumina template was removed using an aqueous HF solution and a sample removed using an aqueous NaOH solution.
FIG. 13 shows the electrical conductivity of the P3HT nanowires prepared in Example 4 with respect to the samples in which the alumina template was removed using HF aqueous solution and the samples removed using NaOH aqueous solution.
14 is a result of measuring the field emission effect on the P3MT nanotubes prepared in Example 2.

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments of the present invention, but the present invention is not limited thereto.

Examples 1-7

The monomer and the dopant were dissolved in 100 ml of acetonitrile and stirred for 30 minutes to prepare a homogeneous electrochemical polymerization solution. As a porous material, gold was deposited on one side using Anodisc Membrane (diameter: 25 mm, pore size 0.2 μm) purchased from Whatman, and then stainless steel (width = 3 cm, length = 15 cm, thickness = 0.5 Mm) It was attached to one side of the electrode and sealed around the porous material with silicon tape as an insulator for preventing solution injection and intensive polymerization on the sample side. Position the electrode with the porous material attached and the electrode not attached to each other so as to maintain a 3 cm gap in the polymerization solution prepared above, and apply a current between both electrodes to maintain a voltage of 1.2 to 3 V. The reaction temperature is -40 ° C. Maintained. After maintaining the polymerization time appropriately, the porous material used for the polymerization was dissolved in NaOH solution to obtain a polythiophene-based polymer nanomaterial and nanowires to which the dedoping effect was imparted. A doped polythiophene-based polymer nanomaterial and nanowires were obtained. The monomers, dopants, applied currents and times used in Examples 1-7 are shown in Table 1. The diameters of the nanotubes and nanowires obtained in each example were 150-200 nm, and their lengths and shapes are shown in Table 2 below. Meanwhile, SEM and TEM images of the polythiophene-based nanomaterials prepared in Examples 1 to 5 are shown in FIGS. 1 to 7, and it can be seen that nano-sized tubes or wires are formed.

Monomer Dopant Current applied
(mA) Polymerization time
(minute) Example 1 Thiophene (0.5M) TBACF ₃ SO ₃ (0.1M) 5 2 Example 2 3-methylthiophene (0.5M) TBAPF ₆ (0.1M) 10 5 Example 3 3-methylthiophene (0.5M) DBSA (0.1M) 10 20 Example 4 3-hexylthiophene (0.5M) BMIMPF ₆ (0.1M) 10 20 Example 5 3-octylthiophene (0.5M) TBAPF ₆ (0.1M) 10 5 Example 6 3-methylthiophene (0.5M) BMIMPF ₆ (0.1M) 10 5 Example 7 3-methylthiophene (0.5M) BMIMPF ₆ (0.1M) 10 20

Distilled water Length (㎛)  shape Example 1 10 Nanotube Example 2 20 Nanotube Example 3 20 Nanowire Example 4 40 Nanowire Example 5 25 Nanotube Example 6 35 Nanotube Example 7 10 Nanowire

Test Example 1

Absorption Spectrum and Emission Spectrum Measurements

UV / Vis absorption spectra and emission spectra of the P3MT nanotubes prepared in Example 2 were measured under methanol solution and the results are shown in FIG. 8. Referring to FIG. 8 (a), it can be seen that the maximum emission peak is observed at about 500 nm while the bipolaron absorption is strongly induced.

On the other hand, the P3MT nanotubes prepared in Example 2 treated with NaOH aqueous solution, and the sample treated with HF aqueous solution, the nanotubes using a confocal scanning laser microscope (Confocal scanning laser microscope) The emission spectrum was measured on one strand and the result is shown in FIG. 9. 9, it can be seen that the emission intensity is stronger when the alumina template is removed with an aqueous NaOH solution. That is, according to the present invention it is possible to further increase the light emission intensity than in the case of the conventional bulk polythiophene-based polymer.

In addition, in order to control the optical luminescence properties of the P3MT nanotubes prepared in Example 6, the samples from which the alumina template was removed using HF aqueous solution, and the samples dedoped using cyclovoltametry were emitted. The change in the spectrum was measured and the results are shown in FIG. 10. Referring to FIG. 10, in the case of the P3MT nanotubes treated with the HF aqueous solution, the red light transition occurs at 550 nm in the case where the maximum emission peak observed at about 500 nm is dope. Therefore, according to the present invention it can be seen that the polythiophene-based polymer nanomaterial made of nanotubes or nanowires can change the light emission characteristics through an additional treatment process.

FIG. 11 shows the results of measuring absorption spectra and emission spectra under a chloroform solvent for the samples in which the alumina template was removed using an aqueous HF solution and the sample removed using an aqueous NaOH solution in the P3MT nanotube prepared according to Example 3. It was. Referring to FIG. 11, it can be seen that there is a difference between the two samples in the absorption spectrum, so that the optical properties can be adjusted. In the case of the emission spectrum, the maximum emission peak is observed at about 530 nm even when the HF aqueous solution is treated. In the case of the sample treated with the aqueous NaOH solution, the maximum emission peak was observed at about 555 nm, which is a red transition, and it can be seen that the emission characteristics can be adjusted.

FIG. 12 shows the results of measuring absorption spectra and emission spectra under a chloroform solvent for the samples in which the alumina template was removed using an aqueous HF solution and the sample removed using an aqueous NaOH solution in the P3HT nanowire manufactured according to Example 4. It was. Referring to FIG. 12, a red transition occurs in a sample treated with an aqueous NaOH solution, and a yellowish green emission can be observed in a sample treated with an aqueous HF solution, whereas in a sample treated with an aqueous NaOH solution, yellow-red emission occurs. Can be observed. Therefore, according to the present invention, it can be seen that the optical properties of the polythiophene-based polymer nanomaterial can be easily adjusted.

Test Example 2

Electrical conductivity measurement

In the P3HT nanowires prepared in Example 4, the electrical conductivity was measured for the samples from which the alumina template was removed using HF aqueous solution and the samples removed using NaOH aqueous solution, and the results are shown in FIG. 13. It can be seen that the conductivity when treated with an aqueous solution of HF is 8.94 × 10 ⁻³ S / cm, which is significantly higher than that obtained when treated with an aqueous NaOH solution, 1.58 × 10 ⁻⁵ S / cm. That is, according to the present invention, the electrical conductivity can also be easily adjusted.

Test Example 3

Field emission  Measuring effect characteristics

The field emission effect of the P3MT nanotubes prepared in Example 2 was measured and the results are shown in FIG. 14. Referring to FIG. 14, the conventional bulk polythiophene-based polymer exhibits excellent field emission characteristics in which turn-on starts at about 6 V / μm and about 0.8 mA / cm ² flows at 12 V / μm. Has electrical properties that have not been observed, and thus can be applied to field emission devices.

Test Example 4

PL  Efficiency measurement

P3MT nanowires prepared by Example 7 (with alumina template removed with aqueous HF solution and alumina template with NaOH aqueous solution) and conventional bulk P3MT were measured for PL efficiency (Photo Luminescent efficiency) and the results were as follows. It is shown in Table 3. The PL efficiency was measured according to a conventionally used method, which may be referred to, for example, the method disclosed in Chemical Physical Letters 241 (1995) 89-96.

PL efficiency Example 7 (P3MT nanowires by HF aqueous solution) 0.045 Example 7 (P3MT nanowires by NaOH aqueous solution) 0.102 Bulk P3MT Thin Films 0.02

Referring to Table 3, in the case of the P3MT nanowires according to the present invention, when compared to the bulk P3MT thin film, it can be seen that the PL efficiency is increased by at least 2.25 times to 5 times, thus, the conventional bulk polythiophene-based polymer It can be seen that the emission intensity is increased than in the case of.

Claims (5)

(a) preparing an electrochemical polymerization solution by adding and stirring at least one monomer and a dopant selected from the group consisting of thiophene, 3-methyl thiophene, 3-hexyl thiophene, and 3-octyl thiophene to the polar solvent;
(b) depositing a metal on one side of the alumina template with nano pores and then attaching it to a stainless electrode;
(c) surrounding the alumina template with silicon tape to prevent a stainless electrode from contacting the polymerization solution;
(d) immersing the prepared electrode and another stainless electrode in the polymerization solution at regular intervals;
(e) applying a current between both electrodes to electrically polymerize the monomer in the polymerization solution into the nanomaterial in the pores of the alumina template; And
(f) removing the alumina template into which the nanomaterial is inserted and simultaneously removing the alumina template using NaOH, or removing the alumina template using NaOH or de-doping using an aqueous HF solution. Optical Properties Control Method of Offenic Polymer Nanomaterial. The method of claim 1, wherein the polar solvent is any one selected from the group consisting of H ₂ O, acetonitrile, and N-methyl pyrrolidinone. The method of claim 1 wherein the dopant is tetrabutylammonium hexafluorophosphate (TBAPF ₆ ), 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF ₆ ), p-dodecylbenzenesulfonic acid (DBSA) , Tetrabutylammonium tetrafluoroborate (TBABF ₄ ), and tetrabutylammonium trifluoromethanesulfonate (TBACF ₃ SO ₃ ) is one of the polythiophene-based polymer nanomaterial optical How to adjust the characteristics. The method of claim 1, wherein the metal is any one selected from the group consisting of gold, silver, platinum, stainless steel, ITO, or a complex thereof. The method of claim 1, wherein the adjusting of the optical property is performed by immersing the alumina template in an aqueous NaOH solution to increase the luminescence intensity and to red shift the peak emission peak. Way.

Images