KR100822304B1 - Fabrication method of blocking dye-sensitized solar cell with blocking layer having high-crystallinity - Google Patents

Abstract

A method for manufacturing a dye sensitized solar cell having a blocking layer is provided to smoothly move electrons from a semiconductor oxide electrode to a transparent conductive substrate. A transparent conductive photoelectrode substrate(23) and a transparent conductive counter-electrode substrate(27) are prepared. After a blocking layer material is deposited on the photoelectrode substrate, heat treatment is performed on the photoelectrode substrate to form a blocking layer(28). An oxide electrode(21) absorbed with dye is formed on the blocking layer. The counter-electrode substrate is disposed opposite to the oxide electrode of the photoelectrode substrate, and then electrolyte is introduced between the oxide electrode and the counter-electrode substrate.

Description

Manufacturing method of dye-sensitized solar cell with blocking layer which has high crystallinity {FABRICATION METHOD OF BLOCKING DYE-SENSITIZED SOLAR CELL WITH BLOCKING LAYER HAVING HIGH-CRYSTALLINITY}

1 is a view schematically showing the operating principle of a general dye-sensitized solar cell,

2 is a cross-sectional view schematically showing the configuration of a dye-sensitized solar cell including a blocking layer according to an embodiment of the present invention;

3 is a surface FE-SEM image of the blocking layer according to an embodiment of the present invention,

Figure 4 is an XRD graph measuring the crystallinity of the blocking layer according to the present invention,

5 is a current-voltage curve obtained in AM 1.5, 100 mW / cm ² conditions of the dye-sensitized solar cell prepared according to the present invention.

Explanation of symbols on the main parts of the drawings

21: semiconductor oxide electrode 22: dye molecule

23: photoelectrode transparent conductive substrate 25: platinum layer

26: electrolyte 27: counter electrode transparent conductive substrate

28: barrier layer 29: thermoplastic polymer

The present invention relates to a method for manufacturing a dye-sensitized solar cell having a blocking layer having a high crystal.

Conventional silicon solar cells absorb electrons to create electron-hole pairs and transmit the same, whereas dye-sensitized solar cells absorb electrons to generate electron-hole pairs. It has a structure that is divided into a dye oxide molecule and a semiconductor oxide electrode which transfers the generated electrons.

A representative example of dye-sensitized solar cells known to date was published in 1991 by Gratzel et al. Therefore, it attracts many people in that it has the possibility of replacing the existing solar cell.

FIG. 1 is an explanatory view showing the operation principle of a general dye-sensitized solar cell. The dye 12 adsorbed on the semiconductor oxide electrode 11 absorbs sunlight and is excited in a ground state (D ⁺ / D). in ^{excited state, D + / D *} ) by electron transfer electron-hole pairs constitute the electron excited state are injected into the conduction band (conduction band, e _CB) of semiconductor oxide. Electrons injected into the semiconductor oxide electrode 11 are transferred to the transparent conductive substrate 13 through the interparticle interface, and then moved to the charging electrode 15 coated with the platinum layer 16 through the external wire 14. An electrolyte including an oxidation-reduction pair 17 is injected between the semiconductor oxide electrode 11 and the counter electrode 15. The dye 12 oxidized by solar absorption receives the electrons provided by the redox-reduction pair 17 and is reduced again. At this time, the redox pair 17 supplying the electrons reaches the counter electrode 15. Reduction by one electron completes the operation of the dye-sensitized solar cell. In addition, the load L is connected to the transparent conductive substrate 13 and the counter electrode 15 in series to measure a short circuit current, an open voltage, a filling factor, and the like. It is determined by the product of the short-circuit current, the open voltage and the filling factor, so each value must be improved to improve it.

One way to improve these values in dye-sensitized solar cells is to form a barrier layer between the semiconductor oxide electrode and the transparent conductive substrate to facilitate good contact between the semiconductor oxide electrode and the transparent conductive substrate and to facilitate the transfer of electrons. For example, a method of preventing leakage of electrons transferred from a transparent conductive substrate is mentioned.

Patents previously published as a method of improving the efficiency of dye-sensitized solar cells by forming such a barrier layer are as follows. That is, Korean Patent Publication No. 2005-0058695, Korean Patent Publication No. 2005-0115406, and the like.

However, looking at the examples and comparative examples described in the above patents, it can be seen that the open circuit voltage of the examples is similar or rather lower than the comparative example. This indicates that the density of electrons in the semiconductor oxide electrode has not increased, which means that the leakage of electrons transferred from the transparent conductive substrate is not effectively controlled.

In addition, when the material used as the barrier layer and the material of the semiconductor oxide electrode is different from the existing patent, there is a phenomenon that the interface characteristics deteriorate, which is also a factor that hinders the performance improvement of the dye-sensitized solar cell.

The present invention is to solve the above problems, to provide a method for manufacturing a highly crystalline blocking layer through the deposition process and heat treatment process, and the object is to improve the performance of the dye-sensitized solar cell accordingly.

Dye-sensitized solar cell manufacturing method according to the present invention for achieving this object,

Preparing a transparent conductive photoelectrode substrate and a counter electrode substrate; Depositing a blocking layer material on the photoelectrode substrate and then performing heat treatment to form a blocking layer; Forming an oxide electrode having dye adsorbed on the blocking layer; And arranging a counter electrode substrate facing the oxide electrode of the photoelectrode substrate, injecting an electrolyte between the oxide electrode and the counter electrode substrate, and then sealing the electrode substrate.

At this time, the heat treatment is preferably made for 1 to 300 minutes within the temperature range of 400 to 600 ℃. In addition, it is preferable to maintain isothermally for 10 to 120 minutes within the temperature range of 100 to 200 ℃ between the deposition and heat treatment.

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

Referring to FIG. 2, the dye-sensitized solar cell of the present invention is formed between the photoelectrode transparent conductive substrate 23, the semiconductor oxide electrode 21, the counter electrode transparent conductive substrate 27, and the transparent conductive substrate and the semiconductor oxide electrode. A blocking layer 28, and an electrolyte 26 interposed between the semiconductor oxide electrode and the counter electrode substrate. The photoelectrode substrate 23 and the counter electrode substrate 27 are sealed with a thermoplastic polymer 29 to prevent the electrolyte from leaking out.

Here, the photoelectrode or counter electrode transparent conductive substrates 23 and 27 include a conductive thin film formed on a glass substrate or a flexible polymer substrate as a conductive glass substrate or a conductive flexible polymer substrate, and the conductive thin film is indium tin oxide (ITO). tin oxide), F-doped tin dioxide (FTO) (F-doped SnO ₂ ), or ATO (Antimony Tin Oxide) or FTO is coated on the ITO. In addition, a platinum layer 25 may be formed inside the counter electrode transparent conductive substrate 27.

In addition, the semiconductor oxide electrode 21 includes a semiconductor oxide layer formed on a transparent conductive substrate and a dye molecule 22 adsorbed on the semiconductor oxide layer, wherein the dye is a ruthenium-based dye or a coumarin-based dye. Organic dyes are preferred.

The present invention forms a highly crystalline semiconductor oxide blocking layer by depositing a transition metal or a transition metal oxide on a transparent conductive substrate and then heat-treating the same, thereby forming a transparent crystalline substrate and a semiconductor oxide electrode to be formed thereon. The present invention provides a method of improving the energy conversion efficiency of a dye-sensitized solar cell by improving contactability as well as facilitating electron transfer from a semiconductor oxide electrode to a transparent conductive substrate and controlling electron outflow from the transparent conductive substrate.

As the transition metal deposited on the transparent conductive substrate for manufacturing the blocking layer for a dye-sensitized solar cell according to the present invention, any one selected from titanium (Ti), indium (In), zinc (Zn), tin (Sn), and tungsten (W) One may be used, and the transition metal oxide may be titanium (Ti) oxide, indium (In) oxide, zinc (Zn) oxide, tin (Sn) oxide, tungsten (W) oxide, lead (Pb) oxide, iron titanium ( FeTi) oxide, manganese titanium (MnTi) oxide and barium titanium (BaTi) oxide may be used any one. Preferably, titanium dioxide (TiO ₂ ) capable of having an anatase crystallinity excellent in electron transfer ability is preferable.

In addition, the size of the particles deposited to form the barrier layer is preferably controlled in the range of 0.1 ~ 10 nm, the thickness of the barrier layer prepared through the method is preferably 1 ~ 500 nm.

The barrier layer material may be deposited by sputtering, chemical vapor deposition (CVD), evaporation, electrochemical deposition, or spin-coating.

The conduction band energy level of the blocking layer is lower than or equal to that of the semiconductor oxide electrode, and higher than or equal to the photoelectrode transparent conductive substrate.

After depositing the transition metal or transition metal oxide, a heat treatment process is performed to produce a transition metal oxide having high crystallinity, wherein the temperature is 400 to 600 ° C., and the holding time of the heat treatment is 1 to 300 minutes. More preferably, the heat treatment process is preferably maintained at 450 to 500 ° C. for 30 to 120 minutes.

In addition, when the transition metal is deposited, it is preferable to heat-treat it in a high-purity oxygen (O ₂ ) atmosphere to assist the oxidation process, and after the deposition of the transition metal or transition metal oxide, heat treatment to remove moisture adsorbed on the surface In the middle of the heat treatment for 10 to 120 minutes isothermally in the temperature range of 100 ~ 200 ℃ in the middle is preferable to improve the crystallinity.

When the semiconductor oxide electrode paste is loaded without a separate heat treatment process as in the previously published patents (Korean Patent Publication No. 2005-0058695 and Korean Patent Publication No. 2005-0115406), the barrier layer formed is transparently conductive due to the difference in affinity. It is not fixed to the surface of the substrate and in combination with the upper semiconductor oxide electrode, it does not play a role as a blocking layer, thereby inhibiting the increase in the open voltage of the dye-sensitized solar cell. On the contrary, when the heat treatment process is performed, the deposited barrier layer is strongly bonded to the surface of the transparent conductive substrate and the crystallinity is increased to facilitate electron transfer. As a result, the open voltage, short circuit current, and energy conversion efficiency are greatly increased. You can.

3 shows a surface FE-SEM image of a blocking layer made in accordance with one embodiment of the present invention. Image (a) shows a transparent conductive substrate (FTO) without forming a blocking layer, and image (b) shows a titanium dioxide (TiO ₂ ) blocking layer formed after sputtering on a transparent conductive substrate and heat treatment. It is an image. As shown in the image, it can be seen that titanium dioxide (TiO ₂ ) particles are well formed over the entire surface of the transparent conductive substrate.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the embodiments of the present invention illustrated in the following may be modified in many different forms and the scope of the present invention is not limited or limited to the embodiments described in the following.

(Example 1) Titanium dioxide block the (TiO ₂₎ sputtering (sputtering), and heat-treated layer (blocking layer ) manufacturing

Titanium dioxide (TiO ₂ ) powder was pressed with a press to produce a titanium dioxide (TiO ₂ ) target, then mounted on a sputtering device and sputtered at 85 W, 10 mTorr, and room temperature for 1200 seconds to provide transparent conductivity. A 50 nm thick film was obtained on the substrate. After sputtering was completed, the temperature was raised to 4 ° C. per minute from room temperature to 150 ° C. in an air atmosphere, and maintained at isothermal at 150 ° C. for 30 minutes to remove moisture, and then heated up to 500 ° C. at 4 ° C. per minute. After heat treatment at 500 ° C. for 15 minutes, the crystallinity of the deposited titanium dioxide (TiO ₂ ) was improved and then naturally cooled. Figure 4 (a) is a graph measuring the crystallinity of the barrier layer prepared in Example 1 by XRD. As can be seen in the figure, the peak of TiO ₂ anatase 101 measured at around 25.2 ° after heat treatment can be seen.

(Example 2), titanium (Ti) using block the sputtering (sputtering), and heat-treated layer (blocking layer ) manufacturing

The titanium (Ti) target was mounted on a sputter apparatus and sputtered at 100 W, 2 mTorr, and 100 seconds at room temperature to obtain a 30 nm thick film on the transparent conductive substrate. The sputtered titanium (Ti) was heated to 4 ° C. per minute from room temperature to 150 ° C. in a high purity oxygen (O ₂ ) atmosphere and kept at 150 ° C. for 30 minutes to remove water, and then to 500 ° C. at 4 ° C. It heated up. 500 ℃ the titanium dioxide is deposited titanium (Ti) subjected to heat treatment for 60 minutes (TiO ₂₎ was oxidized to improve the crystallinity of the titanium dioxide (TiO ₂₎ was naturally cooled. Figure 4 (b) is a graph measuring the crystallinity of the barrier layer prepared in Example 2 by XRD. As can be seen in the figure, the TiO ₂ rutile (110) peak measured near 27.4 ° after the heat treatment can be seen.

Comparative Example 1 Transparent Conductive Substrate without Forming Blocking Layer

Comparative Example 2 A transparent conductive substrate which was not subjected to a separate heat treatment after depositing titanium dioxide ( TiO ₂ ) as in Example 1

Experimental Example

Titanium dioxide (TiO ₂ ) paste (STI, 18NR-T) was coated on a blocking layer prepared according to the above embodiments and comparative examples by a doctor blade method, and then, at room temperature in an air atmosphere. To 150 ° C. per minute at 4 ° C. and maintained at 150 ° C. for 30 minutes. Thereafter, the temperature was again increased to 4 ° C. per minute to 500 ° C., and heat-treated at 500 ° C. for 15 minutes, followed by natural cooling, to form a titanium dioxide (TiO ₂ ) electrode having a thickness of about 12 μm.

The titanium dioxide (TiO ₂ ) electrode was immersed in a dye solution for 24 hours to adsorb dye molecules. In this experiment, a N719 (Solaronix) / ethyl alcohol solution of 0.5 mM concentration was used.

Hexachloroplatinic acid (H ₂ PtCl ₆ · xH ₂ O, Aldrich) / isopropyl alcohol solution at 10 mM concentration was spin coated onto the transparent conductive substrate (1st; 500 rpm, 5 sec; 2nd; 1000 rpm, 5 sec; 3rd; 2000 rpm, 40 sec) and then heated to 4 ° C. per minute from room temperature to 400 ° C. in an air atmosphere, and heat-treated at 400 ° C. for 15 minutes, followed by natural cooling.

The electrolyte is a liquid electrolyte with an iodine-based redox pair, for example 1,2 M-dimethyl-3-hexyl-imidazolium iodide (1,2-dimethyl-3-hexyl-imidazolium iodide) of 0.6 M, A mixture of acetonitrile and 3-methoxypropionitrile in a 1: 1 mixture of 0.2 M lithium iodide and 0.1 M iodine (I ₂ ) After dissolving in solution, 4-tertiary-butyl pyridine was added at a concentration of 0.5 M as an additive to increase the open voltage.

As a thermoplastic polymer to prevent leakage of electrolyte, Surlyn having a thickness of 25 μm was used.

In Figure 5 (a) dye-sensitized solar cell without the blocking layer (Comparative Example 1), (b) dye-sensitized solar cell (Comparative Example 2), (c) Example after the formation of the blocking layer is not subjected to a separate heat treatment The dye-sensitized solar cell prepared in Example 1 and (d) the dye-sensitized solar cell prepared in Example 2 were measured at AM 1.5 and 100 mW / cm ² , and the exact values are shown in Table 1.

Table 1 Comparison of Physical Properties of Comparative Examples 1 and 2 and Examples 1 and 2

Opening voltage (V) Short circuit current (mA / cm ² ) Fill factor (%) Energy conversion efficiency (%) (a) Comparative Example 1 0.739 14.26 69.0 7.26 (b) Comparative Example 2 0.730 15.08 72.8 8.01 (c) Example 1 0.785 16.20 70.5 8.96 (d) Example 2 0.770 15.17 72.2 8.43

5 and Table 1, the solar cells according to Examples 1 and 2 of the present invention compared to the conventional dye-sensitized solar cells showed significantly improved values compared to Comparative Examples 1 and 2 in terms of open voltage and short circuit current. As a result, the energy conversion efficiency was 23% and 16%, respectively, compared to the case of no blocking layer (Comparative Example 1), and 11%, respectively, compared to the case in which no separate heat treatment was performed after forming the blocking layer (Comparative Example 2). , Could increase by more than 5%.

The blocking layer for the highly crystalline dye-sensitized solar cell according to the present invention facilitates the movement of electrons from the semiconductor oxide electrode to the transparent conductive substrate and effectively reduces the outflow of electrons on the transparent conductive substrate, thereby providing a solar cell. In addition to increasing the short-circuit current and the open voltage, the energy conversion efficiency is improved, and the physical contact between the semiconductor oxide electrode and the transparent conductive substrate is improved, thereby improving durability of the solar cell.

Although the present invention has been described with reference to the illustrated embodiments, it is merely exemplary, and the present invention may encompass various modifications and equivalent other embodiments that can be made by those skilled in the art. Will understand.

Claims (13)

Preparing a transparent conductive photoelectrode substrate and a counter electrode substrate; Depositing a blocking layer material on the photoelectrode substrate and then performing heat treatment to form a blocking layer; Forming an oxide electrode having dye adsorbed on the blocking layer; And And placing a counter electrode substrate facing the oxide electrode of the photoelectrode substrate, injecting an electrolyte between the oxide electrode and the counter electrode substrate, and sealing the electrode substrate. The method of manufacturing a dye-sensitized solar cell, wherein a bonding force between the blocking layer and the photoelectrode substrate is stronger than a bonding force between the blocking layer and the oxide electrode. The method of claim 1, The heat treatment is a method of manufacturing a dye-sensitized solar cell, characterized in that for 1 to 300 minutes in the temperature range of 400 to 600 ℃. The method of claim 1, Method for producing a dye-sensitized solar cell, characterized in that maintained for 10 to 120 minutes isothermally within the temperature range of 100 to 200 ℃ between the deposition and heat treatment. The method of claim 1, The blocking layer raw material is a method of manufacturing a dye-sensitized solar cell, characterized in that containing a transition metal or a transition metal oxide. The method of claim 4, wherein The transition metal is a method of manufacturing a dye-sensitized solar cell, characterized in that any one of titanium (Ti), indium (In), zinc (Zn), tin (Sn) and tungsten (W). The method of claim 4, wherein The transition metal oxide is titanium (Ti) oxide, indium (In) oxide, zinc (Zn) oxide, tin (Sn) oxide, tungsten (W) oxide, lead (Pb) oxide, iron titanium (FeTi) oxide, manganese titanium (MnTi) oxide or barium titanium (BaTi) oxide of any one of the manufacturing method of the dye-sensitized solar cell characterized in that. The method of claim 4, wherein When the blocking layer raw material is a transition metal, the heat treatment is a method of manufacturing a dye-sensitized solar cell, characterized in that in the oxygen atmosphere. The method of claim 1, The deposition of the barrier layer material is performed by any one of sputtering, chemical vapor deposition (CVD), evaporation, electrochemical deposition, and spin-coating. Method of manufacturing dye-sensitized solar cell. The method of claim 1, Method for producing a dye-sensitized solar cell, characterized in that the average size of the particles constituting the barrier layer is adjusted within the range of 0.1 ~ 10nm. The method of claim 1, The thickness of the blocking layer is controlled in the range of 1 to 500nm manufacturing method of the dye-sensitized solar cell. delete The method of claim 1, The conduction band energy level of the blocking layer is lower than or equal to the oxide electrode and higher than or equal to the photoelectrode substrate. The method of claim 1, The blocking layer is a method of manufacturing a dye-sensitized solar cell, characterized in that to have anatase (rutile) crystallinity.

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