KR101601243B1 - Method of manufacturing counter electrode for dye-sensitized solar cell using nitrogen doped titanium dioxidecarbon nanofiber composite - Google Patents

Abstract

The present invention relates to a nitrogen-doped titanium dioxide-carbon nanofiber composite material and a method for producing the same, and more particularly, to a titanium dioxide-carbon nanofiber composite material containing titanium dioxide, nitrogen-doped titanium dioxide, titanium nitride and carbon nanofibers, Wherein the doped titanium dioxide comprises 3.4 to 13.8 wt% of the carbon nanofibers and the nitrogen-doped titanium dioxide is an anatase phase. The nitrogen-doped titanium dioxide-carbon nanofiber composite and the carbon nanofiber precursor Dissolving the substance in a solvent, adding and dispersing the titanium dioxide nanoparticles to prepare a spinning solution; Preparing a titanium dioxide-carbon nanofiber composite by electrospunning the spinning solution; And carbonizing the resulting composite in a nitrogen atmosphere. The present invention also relates to a method for producing a nitrogen-doped titanium dioxide-carbon nanofiber composite.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a dye-sensitized solar cell using a nitrogen-doped titanium dioxide-carbon nanofiber composite,

The present invention relates to nitrogen-doped titanium dioxide-carbon nanofiber composites and methods of making the same. The present invention also relates to a method for producing a counter electrode for a dye-sensitized solar cell using the nitrogen-doped titanium dioxide-carbon nanofiber composite.

Dye-sensitized solar cells (DSSCs) have been vigorously studied since 1991, when they introduced photoelectric conversion research results in Switzerland due to advantages such as simple structure, low manufacturing cost, use of eco-friendly materials and efficient light collection efficiency It is progressing. Dye-sensitized solar cells generally consist of three main components: a working electrode, a counter electrode and an electrolyte. The iodine ion (I ^- ) and the oxidized iodide ion (I ₃ ^- ) in the electrolyte, Oxidation reaction.

Generally, pure platinum (Pt) is mainly used as a counter electrode of a dye-sensitized solar cell, and it is possible to reduce an overvoltage and reduce I ₃ ^- to I ^- in an electrolyte. However, these pure platinum are too expensive to be used, and the platinum price is also continuously increasing. For this reason, the development of a catalyst containing no platinum is essential for the development of a low-cost dye-sensitized solar cell. One of the substitute materials for Pt is carbon nanofibers (CNFs), and carbon nanofibers have high catalytic activity with low unit cost, abundant resources, large surface area and chemical stability for I ^- oxidation reduction reaction. There are various advantages. In spite of these advantages, carbon nanofibers have a lower power conversion efficiency (PCE) than pure platinum. To improve the performance of carbon nanofibers, metal nanoparticles are physically mixed with carbon nanofibers to form counter electrodes There is still a problem that the power conversion efficiency is low.

Examples of related prior arts include nanocomposites comprising titanium oxide / metal nanoparticles / carbon nanostructure described in Korean Patent Laid-Open Publication No. 10-2013-0043458 (published on March 30, 2013), a method for producing the nanocomposite, There is a battery electrode.

Accordingly, the present invention is to provide a nitrogen-doped titanium dioxide-carbon nanofiber composite exhibiting high power conversion efficiency without using high cost platinum as a counter electrode and a method for manufacturing the same. The present invention also provides a method for producing a counter electrode for a dye-sensitized solar cell using the nitrogen-doped titanium dioxide-carbon nanofiber composite.

The problems to be solved by the present invention are not limited to the above-mentioned problem (s), and another problem (s) not mentioned can be understood by those skilled in the art from the following description.

In order to solve the above-described problems, the present invention provides a method for preparing a spinning solution, comprising: dissolving a carbon nanofibre precursor material in a solvent, adding and dispersing titanium dioxide nanoparticles to prepare a spinning solution; Preparing a titanium dioxide-carbon nanofiber composite by electrospunning the spinning solution; And carbonizing the composite material in a nitrogen atmosphere. The present invention also provides a method for producing a nitrogen-doped titanium dioxide-carbon nanofiber composite material.

At this time, the carbon nanofiber precursor material may include two or more kinds selected from the group consisting of polyacrylonitrile, poly (vinylpyrrolidone), polymethyl methacrylate, and polyethylene oxide.

The solvent may be selected from the group consisting of N, N-dimethylformamide, tetrahydrofuran, N-methylpyrrolidone, toluene, acetone and dimethylacetamide.

The titanium dioxide nanoparticles are added in an amount of 3.4 to 13.8 wt% of the carbon nanofibre precursor material.

Wherein the electrospinning is performed with a voltage of 12 to 14 kV and a feed rate of the spinning solution of 0.02 to 0.04 mL / h.

The carbonization is performed at 700 to 900 DEG C for 2 hours.

In addition, the method of manufacturing a nitrogen-doped titanium dioxide-carbon nanofiber composite according to the present invention may further include stabilizing the complex at 220 to 280 ° C for 2 hours after the titanium dioxide-carbon nanofiber composite is prepared .

Also, the present invention includes titanium dioxide, nitrogen-doped titanium dioxide, titanium nitride, and carbon nanofibers, wherein the titanium dioxide and nitrogen-doped titanium dioxide comprise 3.4 to 13.8 wt% of the carbon nanofibers, Wherein the nitrogen-doped titanium dioxide is an anatase phase.

The present invention also provides a method for producing a titanium dioxide nanofiber composite material, comprising the steps of dissolving a carbon nanofibre precursor material in a solvent, adding and dispersing titanium dioxide nanoparticles to prepare a spinning solution, and electrospinning the spinning solution to prepare a titanium dioxide- Preparing a nitrogen-doped titanium dioxide-carbon nanofiber composite comprising the step of carbonizing the composite thus produced in a nitrogen atmosphere; Dissolving the prepared nitrogen-doped titanium dioxide-carbon nanofiber composite, Ketjenblack and polyvinylidene difluoride in a solvent; And printing the prepared mixed solution on a fluorine-doped tin oxide substrate, followed by drying. The present invention also provides a method of manufacturing a counter electrode for a dye-sensitized solar cell.

At this time, the printing is a screen printing method using squeeze.

According to the present invention, nitrogen-doped titanium dioxide is uniformly distributed on the inside and on the surface of the carbon nanofiber, and the surface roughness of the carbon nanofiber is increased. In addition, a TiN phase is formed to improve electrical characteristics and catalyst characteristics, when used as a counter electrode, the photocurrent density and the filling rate are improved to improve the power conversion efficiency.

In addition, it is possible to uniformly disperse TiO ₂ in the solution by adding nano-sized TiO ₂ to the carbon nanofibre precursor solution, and to manufacture titanium dioxide-carbon nanofiber composite by a one-pot process using an electrospinning process The manufacturing method is simple, and a high-priced metal such as platinum is not included, so that a solar cell can be manufactured at low cost.

1 is a scanning electron microscope (FE-SEM) photograph of a nitrogen-doped TiO ₂ -carbon nanofiber composite according to the present invention.
2 is a transmission electron microscope (MULTI / TEM) photograph of the nitrogen-doped TiO ₂ -carbon nanofiber composite according to the present invention.
3 (a) shows the XRD results of the carbon nanofibers and the nitrogen-doped TiO ₂ -carbon nanofiber composites prepared in Examples 1 to 3.
FIGS. 3 (b) to 3 (c) are XPS measurement results of the nitrogen-doped TiO ₂ -carbon nanofiber composite prepared in Example 3. FIG.
4 (a) is a cyclic voltammetry curve of pure Pt, carbon nanofibers and the nitrogen-doped TiO ₂ -carbon nanofibers prepared in Examples 1 to 3.
4 (b) is a photocurrent density (J) -voltage (V) curve of a dye-sensitized solar cell including a counter electrode made of a nitrogen-doped TiO ₂ -carbon nanofiber composite according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving it will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings.

The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

The present invention relates to a method for producing carbon nanofibers, comprising: dissolving a carbon nanofibre precursor material in a solvent; adding and dispersing titanium dioxide nanoparticles to prepare a spinning solution;

Preparing a titanium dioxide-carbon nanofiber composite by electrospunning the spinning solution; And

And carbonizing the composite thus prepared in a nitrogen atmosphere. The present invention also provides a method for producing a nitrogen-doped titanium dioxide-carbon nanofiber composite.

The nitrogen-doped titanium dioxide-carbon nanofiber composite according to the present invention is characterized in that nitrogen-doped titanium dioxide is uniformly distributed on and inside the carbon nanofiber and the surface roughness of the carbon nanofiber is increased and a TiN phase is formed, The catalyst characteristics can be improved. In addition, when the complex is used as a counter electrode of a solar cell, the photocurrent density and the filling rate are improved due to the improved electrical characteristics and catalyst characteristics, thereby improving the power conversion efficiency of the solar cell. In addition, it is possible to uniformly disperse TiO ₂ in the solution by adding nano-sized TiO ₂ to the carbon nanofibre precursor solution, and to manufacture titanium dioxide-carbon nanofiber composite by a one-pot process using an electrospinning process The manufacturing method is simple, and a high-priced metal such as platinum is not included, so that a solar cell can be manufactured at low cost.

The method for preparing a nitrogen-doped titanium dioxide-carbon nanofiber composite according to the present invention includes dissolving a carbon nanofibre precursor material in a solvent, adding titanium dioxide nanoparticles, and dispersing the carbon nanofibre precursor material to prepare a spinning solution.

At this time, the carbon nanofiber precursor material may include two or more kinds selected from the group consisting of polyacrylonitrile, poly (vinylpyrrolidone), polymethyl methacrylate, and polyethylene oxide.

The solvent may be selected from the group consisting of N, N-dimethylformamide, tetrahydrofuran, N-methylpyrrolidone, toluene, acetone and dimethylacetamide.

The titanium dioxide nanoparticles are preferably added in an amount of 3.4 to 13.8 wt% of the carbon nanofiber precursor material. When the titanium dioxide nanoparticles are added in an amount of less than 3.4% by weight, the addition amount of titanium dioxide is so small that the catalytic properties are not improved and the electrical characteristics are not improved by the surface roughness, If it is added in an amount exceeding the weight%, the viscosity of the electrospinning solution increases and the electrospinning process can not be used.

Next, a method of producing a nitrogen-doped titanium dioxide-carbon nanofiber composite according to the present invention includes a step of preparing a titanium dioxide-carbon nanofiber composite by electrospunning the spinning solution.

At this time, it is preferable that the electrospinning is performed at a voltage of 12 to 14 kV and a feed rate of the spinning solution is 0.02 to 0.04 mL / h. If the voltage is less than 12 kV, there is a problem that a composite is not produced. If the voltage is more than 14 kV, there is a problem that crystallinity is deteriorated because the composite does not have sufficient time for self-alignment. In addition, when the feed rate is less than 0.02 mL / h, there is a problem that a composite in the form of a fiber can not be produced. When the feed rate is more than 0.04 mL / h, a nano-shaped composite can not be produced.

The method for producing a nitrogen-doped titanium dioxide-carbon nanofiber composite according to the present invention includes carbonizing the composite thus prepared in a nitrogen atmosphere.

Due to the above process, titanium dioxide is doped with nitrogen to form a TiN phase, and the charge transfer resistance can be reduced to improve the performance of the solar cell.

The carbonization is preferably performed at 700 to 900 ° C for 2 hours. When the carbonization is less than 700 ° C, there is a problem that the non-carbon element contained in the precursor is not completely removed. When the carbonization exceeds 900 ° C, there is a problem that rutile titanium dioxide is formed, have.

In addition, the method of manufacturing a nitrogen-doped titanium dioxide-carbon nanofiber composite according to the present invention may further include stabilizing the complex at 220 to 280 ° C for 2 hours after the titanium dioxide-carbon nanofiber composite is prepared .

Due to the stabilization process, titanium dioxide in the carbon nanofibers can be stably bonded. When the temperature is lower than 220 캜, the carbon nanofibers precursor (particularly, polyacrylonitrile) does not react sufficiently with oxygen to form a ladder structure (plate-like structure) C, there is a problem that the carbon nanofiber precursor is decomposed.

In addition, the present invention includes titanium dioxide, nitrogen-doped titanium dioxide, titanium nitride, and carbon nanofibers,

The nitrogen-doped titanium dioxide contains 3.4 to 13.8 wt% of carbon nanofibers and is dispersed in the interior and the surface,

The nitrogen-doped titanium dioxide-carbon nanofiber composite is characterized in that the nitrogen-doped titanium dioxide is in an anatase phase.

The titanium in the nitrogen-doped titanium dioxide-carbon nanofiber composite according to the present invention is composed of a TiO ₂ phase, a nitrogen-doped TiO ₂ phase and a TiN phase and contains nitrogen-doped titanium dioxide to improve the surface roughness of the carbon nanofibers Ion can be improved to improve the reduction of I ₃ ^- ions and to improve catalytic activity due to the formation of TiN phase. In addition, the current density can be improved by forming a defect in which titanium dioxide is doped with nitrogen and converted from rutile to anatase phase to serve as a hole trapping point.

The present invention also relates to a method for producing a titanium dioxide-carbon nanofiber composite, comprising: dissolving the nitrogen-doped titanium dioxide-carbon nanofiber composite, Ketjenblack and polyvinylidene difluoride in a solvent; And

And printing the prepared mixed solution on a fluorine-doped tin oxide substrate, followed by drying. The present invention also provides a method for manufacturing a counter electrode for a dye-sensitized solar cell.

At this time, the printing may use a screen printing method using squeeze.

By using the nitrogen-doped titanium dioxide-carbon nanofiber composite according to the present invention in a method of manufacturing a counter electrode for a dye-sensitized solar cell, a photocurrent density and a filling rate can be improved without including platinum, and a photocurrent density And the improvement of the charging rate, the power conversion efficiency of the solar cell can be improved and the performance of the solar cell can be improved.

Example 1: Preparation of nitrogen-doped TiO ₂ -carbon nanofiber composite 1

N, N- dimethylformamide (DMF, Aldrich Co.) polyacrylonitrile in _{(PAN, M w = 150,000 g} / mol, Aldrich Co.) and poly _{(vinylpyrrolidone) (PVP, M w = 1,300,000} g / mol, manufactured by Aldrich) was dissolved to prepare a carbon nanofibre precursor solution, and TiO ₂ nanoparticles (P25, manufactured by Degussa) were dispersed in the precursor solution. At this time, TiO ₂ was added to 3.4 wt% of the precursor solution. The prepared solution was placed in a plastic syringe and electrospinning was carried out at a voltage and a feed rate of 13 kV and 0.03 mL / h, respectively. The electrospun TiO ₂ - carbon nanocomposite composite was stabilized at 230 ° C for 2 hours and carbonized at 800 ° C for 2 hours under nitrogen gas.

Example 2: Preparation of nitrogen-doped TiO ₂ -carbon nanofiber composite 2

A nitrogen-doped TiO ₂ -carbon nanofiber composite was prepared in the same manner as in Example 1, except that 9.6 wt% of TiO ₂ was added to the precursor solution.

Example 3: Preparation of nitrogen doped TiO ₂ -carbon nanofiber composite 3

Nitrogen doped TiO ₂ -carbon nanofiber composite was prepared in the same manner as in Example 1 except that TiO ₂ was added in an amount of 13.8 wt% of the precursor solution.

Example 4: Preparation of a counter electrode of a dye-sensitized solar cell

The nitrogen-doped TiO ₂ -carbon nanofiber composite prepared in Examples 1 to 3, Ketjenblack and polyvinylidene difluoride were mixed in N-methylpyrrolidone by pulverization and pulverized for 4 hours. The pulverized ink was printed on a fluorine-doped tin oxide substrate using a squeeze, followed by drying at 100 DEG C for 12 hours.

Experimental Example 1: Analysis of shape of nitrogen doped TiO ₂ -carbon nanofiber composite

(FE-SEM) and transmission electron microscope (MULTI / TEM) to examine the shapes of the nitrogen-doped TiO ₂ -carbon nanofiber composite and the carbon nanofibers according to the present invention. The results are shown in FIG. 1 And Fig.

(B) is a nitrogen-doped TiO ₂ -carbon nanofiber composite prepared in Example 1, (c) is a nitrogen-doped TiO ₂ composite prepared in Example 2, -Carbon nanofiber composite and (d) the nitrogen-doped TiO ₂ -carbon nanofiber composite prepared in Example 3. As shown in FIG. 1, the diameter of the carbon nanofibers is 191 to 232 nm, that of Example 1 is 194 to 261 nm, that of Example 2 is 189 to 322 nm, and that of Example 3 is 281 to 358 nm. Carbon nanofibers exhibited a smooth surface morphology, but Examples 1 to 3 were not rough and flat due to the incorporation of nitrogen-doped TiO ₂ nanoparticles in the carbon nanofibers. Increasing the weight ratio of nitrogen-doped TiO ₂ nanoparticles in the complex also increased the diameter and surface roughness of the composite. In addition, it can be seen that, in Examples 1 to 3, the nitrogen-doped TiO ₂ nanoparticles are retained in the nanofiber form despite being bonded.

2 (a) shows the carbon nanofibers, and FIGS. 2 (b) to 2 (d) show the nitrogen-doped TiO ₂ -carbon nanofiber composite prepared in Example 3. As shown in Fig. 2 (a), the carbon nanofibers exhibit overall light gray in the carbon nanofiber matrix, indicating that there is one phase in the nanofiber. As shown in FIG. 2 (b), the composite material is composed of nitrogen-doped TiO ₂ nanoparticles and carbon nanofibers which are relatively dark gray and light gray. Further, as shown in Fig. 2 (c), nitrogen-doped TiO ₂ nanoparticles having a diameter of 21 to 35 nm are uniformly dispersed in the carbon nanofibers. As shown in FIG. 2 (d), in a high magnification TEM photograph, the crystalline nitrogen-doped TiO ₂ nanoparticles are surrounded by an amorphous carbon material that appears as a relatively bright color. As a result, the nitrogen-doped TiO ₂ nanoparticles in the carbon nanofibers are bonded.

Experimental Example 2: Analysis of structure and chemical characteristics of nitrogen-doped TiO ₂ -carbon nanofiber composite

Ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) to examine the structure and chemical properties of the nitrogen-doped TiO ₂ -carbon nanofiber composite and carbon nanofibers according to the present invention, Is shown in Fig.

Of Figure 3 (a) is a nitrogen-doped TiO ₂ prepared from carbon nanofibers as Examples 1 to 3 shows the XRD results of the nano-carbon fiber composite. Carbon nanofibers have gentle peaks at about 25 ° and 43 ° corresponding to the (002) and (100) layers of graphite. The composites of Examples 1 to 3 had 2θ = 25.5 °, 37.9 °, 48.2 °, corresponding to the (101), (004), (200), (105) and (204) planes of anatase TiO ₂ , Specific peaks were observed at 54.1 ° and 62.6 °. Another specific peak was observed at 2? = 27.6 °, 36.3 °, 41.5 ° and 55.1 ° corresponding to the (110), (101), (111) and (211) planes of rutile TiO ₂ . Also, the TiN phase is observed at 2? = 43 ° corresponding to the (200) plane, indicating that a TiN phase is formed in the composite by N ₂ gas during carbonization. In addition, TiN, which is similar to the electronic structure of noble metals, has the best catalytic activity for the reduction of I ₃ ^- ions. Referring to FIG. 3 (a), when the amount of nitrogen-doped TiO _{2 in} the composite increases, the peak intensity of the rutile (110) plane decreases while the peak intensity of the anatase (101) plane increases. Nitrogen doping reorganizes the rutile due to the N ^{3 -} lattice replacing the O ^{2 -} lattice, and the oxygen vacancies formed from it act as hole trapping sites to form defects. These results can affect the current density of the dye-sensitized solar cell.

FIGS. 3 (b) to 3 (c) are XPS measurement results for examining the chemical bonding state of the nitrogen-doped TiO ₂ -carbon nanofiber composite prepared in Example 3. FIG. Ti 2p _3/2 photoelectron the XPS core-rebeol spectrum is _{459.0 eV (TiO 2), 458.7} eV (N-TiO 2) and 456.0 eV (TiN) were mainly observed in, Ti 2p _1/2 photoelectron of the core-level spectrum It was observed at _{465.1 eV (TiO 2), 463.8} eV (N-TiO 2) and 461.7 eV (TiN). Specifically, the atomic ratios of the N-TiO ₂ and TiN elements in the nitrogen-doped TiO ₂ -carbon nanofiber composite (Example 3) were 3.7% and 2.5%, respectively. In addition, the O 1s core-level was observed with a large slope at 530.2 eV.

From the XRD and XPS results described above, it can be seen that Ti consists of a TiO ₂ phase, a nitrogen-doped TiO ₂ phase and a TiN phase.

EXPERIMENTAL EXAMPLE 3 Analysis of Open Voltage, Photocurrent Density, Charging Rate and Power Conversion Efficiency of Nitrogen-Doped TiO ₂ -Carbon Nanofiber Composite

The open voltage, the photocurrent density, the filling rate and the power conversion efficiency of the nitrogen doped TiO ₂ -carbon nanofiber composite, pure Pt and carbon nanofiber according to the present invention were analyzed, and the results are shown in FIG.

Of Figure 4 (a) is pure Pt, carbon nanofibers, and Examples 1 to 3 nitrogen-doped TiO ₂ in the - I ³ of the carbon nanofibers, ^- / I ^- in the system to 1.1 V at -0.3 V, 50 mVs ^-1 And a cyclic voltammetry curve measured at the scan speed of the scan line. The catalytic performance of the nitrogen-doped TiO ₂ -carbon nanofibers of Examples 1 to 3 was compared to Pt, which is known as a good catalyst. As shown in Fig. 4 (a), two pairs of redox reactions were observed. Specifically, a positive pair and a negative pair correspond to the oxidation reaction of I ₂ / I ₃ ^- and the reduction reaction of I ₃ ^- / I ^- , respectively. In particular, in the case of the I ₃ ^- + 2 e ^- → ₃ I ^- reaction, the nitrogen-doped TiO ₂ -carbon nanofiber composite prepared in Example 3 exhibits the highest redox current density. Cm < 2 >, 2.01 mA / cm < 2 >, 2.83 mA / cm < 2 >, and 3.06 mA / cm < 2 >, respectively, at 0.51 V for pure Pt, carbon nanofibers and Examples 1 to 3. The pure Pt, carbon nanofibers and the reduction peaks of Examples 1 to 3 were -1.35 mA / cm2, -2.49 mA / cm2, -3.36 mA / cm2 and -3.85 mA / cm2 at -0.22 V . The high carbon nanofiber surface roughness and high catalytic activity for the high carbon nanofiber surface area which exhibits the best current density in the nitrogen-doped TiO ₂ -carbon nanofiber composite prepared in Example 3 and serves as a site for the enhanced reduction of I ₃ ^- TiN phase. These results increase the rate of redox reaction occurring in the counter electrode and increase the catalytic activity of the counter electrode.

FIG. 4 (b) shows the photocurrent density (J) -voltage (V) curve of the dye-sensitized solar cell including the counter electrode made of the nitrogen-doped TiO ₂ -carbon nanofiber composite according to the present invention.

Table 1 below shows the open-circuit voltage, photocurrent density, filling rate and power conversion efficiency of pure Pt, carbon nanofibers, and nitrogen-doped TiO ₂ -carbon nanofiber composites of Examples 1 to 3.

Yes Open-circuit voltage
(V _oc , V) Photocurrent density
(J _sc , mA / cm 2) Charge rate
(ff,%) Power conversion efficiency
(PCE,%) Example 1 0.66 14.82 ± 0.2 48.96 + - 0.2 4.89 ± 0.2 Example 2 0.67 14.96 ± 0.1 59.78 ± 0.1 6.05 ± 0.1 Example 3 0.67 15.65 ± 0.2 60.50 ± 0.3 6.31 ± 0.1 Pt 0.74 14.80 ± 0.2 57.13 ± 0.2 6.27 ± 0.1 CNFs 0.63 12.59 ± 0.1 43.82 ± 0.1 3.54 + - 0.1

As shown in Figure 4 (b) and Table 1 below, the carbon nanofibers have a low fill factor (ff, 43.82%) due to their lowest photocurrent density (J _sc , 12.59 mA / . The open-circuit voltages (V _oc ) of Examples 1 to 3 were similar at 0.67 V, but the charge rate and photocurrent density were largely affected by the catalyst behavior. Specifically, as the amount of nitrogen-doped TiO ₂ nanoparticles in the composite increases, photovoltaic power such as photocurrent density and charge rate is improved. The power conversion efficiency (PCE) was calculated according to the following equation.

[Equation 1]

PCE (%) = [J _sc x V _oc x ff] / [I _max x V _max ]

Where J _sc is the short-circuit photocurrent density, V _oc is the open circuit voltage, f f is the charge rate, I _max is the maximum value of the current, V _max is the maximum value of the voltage to be. The power conversion efficiency was 3.54% in carbon nanofiber, 4.89% in Example 1, 6.05% in Example 2 and 6.31% in Example 3. The highest power conversion efficiency in Example 3 is shown based on the high open-circuit voltage (0.67 V), the highest J _sc (15.65 mA / cm 2) and the highest charge rate (60.50%). It is considered that the improvement in performance is due to the reduction of the charge transfer resistance from the high surface roughness and the presence of the TiN phase in the composite and the reduction of the I ₃ ^- ion. In addition, since the photovoltaic power of Example 3 is higher than that of pure Pt, the nitrogen-doped TiO ₂ -carbon nanofiber composite according to the present invention can be usefully used as a counter electrode in a dye-sensitized solar cell.

Although the nitrogen-doped titanium dioxide-carbon nanofiber composite according to the present invention and the method for manufacturing the same have been described above, it is apparent that various modifications may be made without departing from the scope of the present invention.

Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be determined by the scope of the appended claims and equivalents thereof.

It is to be understood that the foregoing embodiments are illustrative and not restrictive in all respects and that the scope of the present invention is indicated by the appended claims rather than the foregoing description, It is intended that all changes and modifications derived from the equivalent concept be included within the scope of the present invention.

Claims (10)

Preparing a spinning solution by dissolving a carbon nanofibre precursor material in a solvent and adding and dispersing the titanium dioxide nanoparticles to prepare a spinning solution, preparing a titanium dioxide-carbon nanofiber composite by electrospinning the spinning solution, Carbonitriding the composite thus prepared in a nitrogen atmosphere to produce a nitrogen-doped titanium dioxide-carbon nanofiber composite;
Dissolving the prepared nitrogen-doped titanium dioxide-carbon nanofiber composite, Ketjenblack and polyvinylidene difluoride in a solvent; And
And printing the prepared mixed solution on a fluorine-doped tin oxide substrate, followed by drying. The method of manufacturing a counter electrode for a dye-sensitized solar cell,
The method according to claim 1,
Wherein the carbon nanofibre precursor material comprises at least two selected from the group consisting of polyacrylonitrile, poly (vinylpyrrolidone), polymethyl methacrylate, and polyethylene oxide. Gt;
The method according to claim 1,
Wherein the solvent is one selected from the group consisting of N, N-dimethylformamide, tetrahydrofuran, N-methylpyrrolidone, toluene, acetone and dimethylacetamide. Way.
The method according to claim 1,
Wherein the titanium dioxide nanoparticles are added in an amount of 3.4 to 13.8 wt% of the carbon nanofiber precursor material.
The method according to claim 1,
Wherein the electrospinning is performed at a voltage of 12 to 14 kV and a feed rate of the spinning solution of 0.02 to 0.04 mL / h.
The method according to claim 1,
Wherein the carbonization is performed at 700 to 900 ° C for 2 hours.
The method according to claim 1,
Further comprising the step of stabilizing the complex at 220 to 280 ° C for 2 hours after the titanium dioxide-carbon nanofiber composite is prepared. The method of manufacturing a counter electrode for a dye-sensitized solar cell,
The method according to claim 1,
Wherein the printing is a screen printing method using a squeeze method.


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