TWI399460B - Method for manufacturing zinc oxide thin film from zinc oxide precursors - Google Patents

Description

Method for preparing zinc oxide film by using zinc oxide precursor

The invention relates to a zinc oxide film and a preparation method thereof, and in particular to a preparation method for preparing a zinc oxide film by using a zinc oxide precursor film.

Nano zinc oxide has high direct energy gap (about 3.37 eV) and high carrier mobility. Therefore, zinc oxide thin films are widely used in electronic components, semiconductor devices and solar cells.

There are various methods for preparing zinc oxide thin films, and common methods such as chemical vapor deposition (CVD) and electrodeposition (electrodeposition). In the above method, the procedure of the CVD method is complicated, the required equipment is relatively precise, and the reaction temperature is as high as about 500 °C. The electrodeposition method must be electrodeposited at a temperature of 50 ° C or higher to obtain a zinc oxide film, followed by sintering at a high temperature of about 300 to 700 ° C.

It can be seen from the above that the existing zinc oxide film preparation methods are subjected to a high temperature process, thereby limiting the selection of the substrate. In view of this, it is urgent to propose a method for preparing a zinc oxide film, which can prepare a zinc oxide film by using relatively simple equipment and steps, and can use a lower sintering temperature.

Therefore, one aspect of the present invention is to propose an electrochemical preparation method for a zinc oxide thin film, which uses electrochemical technology to form oxygen on a conductive substrate. A zinc precursor film is then sintered, and then the zinc oxide precursor film is sintered to obtain a zinc oxide film. According to the above method, the sintering temperature is at least 150 ° C, so that the zinc oxide precursor can be converted into zinc oxide, and during the sintering process, the lattice structure of the film can be rearranged, and necking occurs between the grains. .

According to an embodiment of the present invention, an electrochemical preparation method of a zinc oxide thin film at least comprises: (1) preparing an electrodeposition solution; and (2) forming a zinc oxide precursor film by placing a conductive substrate in the electrodeposition solution. And coating the film with appropriate parameter conditions; (3) drying the zinc oxide precursor film, wherein the drying temperature is about 15-40 ° C and the relative humidity is about 75% or more; and (4) sintering the zinc oxide precursor film, wherein The sintering temperature is at least 150 ° C to obtain a zinc oxide film.

The above electrodeposition solution contains an aqueous zinc ion solution having a molar concentration of from about 10 ^-1 M to about 1 M. In addition, suitable parameter conditions for forming the zinc oxide precursor film include: the reference electrode is a silver/silver chloride electrode; the counter electrode is a platinum electrode; the deposition potential is about 900-1100 mV; and the working distance is about 1-5 cm.

Another aspect of the present invention provides the use of the above zinc oxide film, which can be used to prepare a photoelectrode element of a dye-sensitized solar cell.

According to a specific embodiment of the present invention, a photoelectrode element of a dye-sensitized solar cell comprises a conductive substrate and a zinc oxide film, wherein the zinc oxide film is on a conductive surface of the conductive substrate.

Still another aspect of the present invention provides a dye-sensitized solar cell using the above-described photoelectrode element.

According to a specific embodiment of the present invention, the dye-sensitized solar cell includes at least the above-described photoelectrode element, counter electrode, and electrolyte. Among them, the electricity The conductive surface of the pole is opposite to the conductive surface of the photoelectrode element. The electrolyte is filled between the photoelectrode element and the counter electrode.

Hereinafter, a method for electrochemically preparing a zinc oxide precursor film and a zinc oxide film will be clarified in a plurality of specific embodiments. Thereafter, a zinc oxide film was prepared as a photoelectrode element of a dye-sensitized solar cell, and a dye-sensitized solar cell was assembled to test the photoelectric conversion efficiency of the dye-sensitized solar cell.

(I) Electrochemical preparation method of zinc oxide film

In one aspect of the invention, a zinc oxide precursor film is prepared by electrochemical method and then a zinc oxide film is prepared. According to the method proposed by the specific embodiment of the present invention, zinc ions and nitrate ions or chloride ions are dissociated in the electrodeposition solution, and form a wrong ion with the water molecules and form a film on the surface of the object to be plated (working electrode).

According to a specific embodiment of the present invention, the electrochemical preparation method of the zinc oxide thin film at least comprises: (1) preparing an electrodeposition solution; (2) forming a zinc oxide precursor film, wherein the conductive substrate is placed in the electrodeposition solution; And coating the film with appropriate parameter conditions; (3) drying the zinc oxide precursor film; and (4) sintering the zinc oxide precursor film to obtain a zinc oxide film, the sintering temperature being at least 150 °C.

According to various embodiments of the invention, the electrodeposition described above is carried out at room temperature. By room temperature is meant to be about 23-27 °C. However, the electrodeposition temperature of the present invention is not limited thereto.

In the electrodeposition, a silver/silver chloride electrode is used as a reference electrode; platinum is used as a counter electrode; and a suitable conductive substrate is used as a working electrode. Other suitable parameters for electrodeposition include a deposition potential of about 900-1100 mV; a working distance of about 1-5 cm; and a working time of about 100-300 minutes. Further, the electrodeposition solution may be simultaneously stirred during electrodeposition, and the concentration of zinc ions in the electrodeposition solution may be replenished as appropriate.

According to a specific embodiment of the present invention, the conductive substrate may be a conductive fabric, a transparent conductive substrate, a flexible substrate, a metal substrate or a metal oxide substrate. By way of illustration and not limitation, the conductive fabric may be made of a conjugated polymer, or a metal fiber/yarn; the transparent conductive substrate may be FTO/glass (fluorinated tin oxide/glass) or ITO/glass (tin oxide) Indium/glass); flexible substrate can be polyethylene terephthalate (PET) substrate, polyethylene naphthalene (PEN), polycarbonate (polycarbonate, PC) Or a polyimide (PI) substrate; the metal substrate can be platinum or stainless steel.

Furthermore, according to a specific embodiment of the present invention, the zinc oxide precursor coating can be dried in a constant temperature and humidity apparatus, wherein the drying temperature used is about 15-40 ° C and the relative humidity is about 75% or more. According to various experimental examples of the present invention, the drying temperature used was about 30 ° C and the relative humidity was about 80%.

According to the embodiment of the present invention, the sintering temperature is at least 150 ° C, and the zinc oxide precursor can be converted into zinc oxide, and during the sintering process, the lattice structure of the thin film is rearranged, and the crystal grains are coagulated to cause necking ( Necking) phenomenon. According to an embodiment of the invention, the sintering temperature may also be higher than 150 ° C, and a suitable sintering temperature is about 150-450 ° C. In general, the sintering temperature may depend on the type of conductive substrate to be used, such as the sintering temperature of the flexible substrate. Usually not more than 200 ° C.

Further, the above sintering treatment can be carried out in a manner of stepwise temperature rise and temperature drop. For example, a first warming phase, a second warming phase, and a cooling phase can be employed. Specifically, in the first temperature rising stage, the temperature is raised from room temperature to about 100-150 ° C at a rate of about 2 ° C / minute and the temperature is about 30-120 minutes; in the second temperature rising stage, about 2 ° C / minute. The rate is again raised to about 150-450 ° C and held at a constant temperature of about 30-120 minutes; and in the cooling stage, the temperature is lowered to room temperature at a rate of about 2 ° C / minute.

According to various embodiments of the present invention, different zinc oxide precursor films can be obtained by using different electrodeposition solution compositions. For example, the electrodeposition solution composition may comprise a zinc nitrate solution of about 10 ^-1 M to about 1 M to obtain zinc oxynitrate (Zn ₅ (OH) ₈ (NO ₃ ) ₂ .2H ₂ O, zinc hydroxynitrate )film. In another example, the electrodeposition solution composition may comprise a zinc chloride solution of about 10 ^-1 M to about 1 M to obtain zinc oxychloride (Zn ₅ (OH) ₈ Cl ₂ .H ₂ O, zinc hydroxychloride). film. Then, the above zinc oxynitrate film or zinc oxychloride film is sintered to obtain a zinc oxide film.

In various experimental examples of the present invention, zinc oxide thin films were prepared using different process parameters in accordance with the above specific examples. Table 1 illustrates the parameters employed in some of the experimental examples of the present invention. In the following Experimental Example 1-9, FTO/glass was used as the working electrode. Further, Experimental Example 1-9 was carried out by means of a stepwise temperature rise and a temperature drop, in which the first temperature rising stage was heated to about 100 ° C, and the second temperature was raised. See Table 1 for the temperature of the stage.

The film was subjected to X-ray diffraction (XRD) analysis before and after sintering of the film to confirm the structure of the film. The above X-ray diffraction analysis is performed by an X-ray diffractometer (model MAC MO3X-HF Diffractometer), and the relevant parameters are as follows: Kα radiation λ=1.5418; scan range 2θ=10-70∘; scan rate 1∘/ Min; voltage 40 kV; current 30 mA.

Fig. 1 is a light diffraction pattern of the film obtained in Experimental Example 4 before sintering and after sintering at about 150 ° C; and Fig. 2 is a light diffraction pattern of the film obtained in Experimental Example 9 before sintering and sintering at about 150 ° C.

It can be found from Fig. 1 that the zinc oxide precursor obtained in Experimental Example 4 is zinc oxynitrate, and the zinc oxynitrate film has almost been converted into a zinc oxide film after being sintered at about 150 ° C for about 1 hour. There are a small number of precursors present. Similarly, it can be seen from Fig. 2 that the zinc oxide precursor obtained in Experimental Example 9 is zinc oxyhydroxide, and the zinc oxyhydroxide film has almost been converted into a film after sintering at about 150 ° C for about one hour. Zinc oxide film, only a small part of the precursor exists.

The results of Fig. 1 and Experimental Examples 1-9 show that a zinc oxide film can be formed on the working electrode after sintering according to the parameter ranges listed in the specific embodiment of the present invention.

(II) Preparation of Photoelectrode Element and Dye Sensitized Solar Cell

Another aspect of the present invention provides the use of the zinc oxide thin film of the above specific embodiment of the present invention, which can be used to prepare a photoelectrode element of a dye-sensitized solar cell.

According to a specific embodiment of the present invention, a photoelectrode element of a dye-sensitized solar cell comprises a conductive substrate and a zinc oxide film according to the above specific embodiment of the present invention, wherein the zinc oxide film is on a conductive surface of the conductive substrate.

According to another embodiment of the present invention, the photoelectrode element of the dye-sensitized solar cell may further comprise titanium oxide, tin oxide, copper oxide or zirconium oxide on the conductive surface of the conductive substrate. For example, a method of the above specific embodiment of the present invention may be used to form a zinc oxide film on a conductive surface of a conductive substrate, and then a material such as titanium oxide is formed thereon. Alternatively, the material layer may be formed on the conductive substrate, and then a zinc oxide film is formed on the conductive surface of the conductive substrate by the method of the above specific embodiment of the present invention. Alternatively, a composite film of titanium oxide and zinc oxide can be formed on the conductive substrate at the same time.

According to a specific embodiment of the present invention, the dye-sensitized solar cell comprises at least a photoelectrode element, a counter electrode, a dye, and an electrolyte according to a specific embodiment of the present invention. Wherein, the conductive surface of the counter electrode is opposite to the conductive surface of the photoelectrode element, the dye is adsorbed on the photoelectrode element, and the electrolyte is filled between the photoelectrode element and the counter electrode.

According to a specific embodiment of the present invention, any dye having a photosensitizing ability can be used to adsorb it on the photoelectrode element. For example, ruthenium complex (ruthenium complex) is one commonly used dye dyes, ruthenium complex dyes include but are not limited to, N ₃ dye (cis-bis (isothiocyanato) bis (2,2'-bipyridyl-4 , 4'-dicarboxylato)-ruthenium (II)), N ₇₁₂ dye ((Bu ₄ N) ₄ [Ru(dcbpy) ₂ (NCS) ₂ ] Complex), N ₇₁₉ dye (cis-bis (isothiocyanato)-bis- (2,2'-bipyridyl-4,4'-dicarboxylato)-ruthenium(II)-bis(tetrabutylam monium) and N ₇₄₉ dye ((2,2':6',2-terpyridine-4,4', 4-tricarboxylate)ruthenium(II)tris(tetrabutylammonium)tris(is othiocyanate)). The above-mentioned dyes are merely illustrative, and it is conceivable that those skilled in the art to which the present invention pertains can also use any suitable dye to prepare a dye-sensitized solar cell according to an embodiment of the present invention.

According to a particular embodiment of the invention, any suitable electrolyte may be filled between the photoelectrode element and the counter electrode. For example, the above electrolyte may be an acetonitrile solution containing 0.5 M lithium iodide and 0.05 M iodine. Specifically, according to the experimental example of the present invention, the electrolyte used was an acetonitrile solution containing 0.5 M lithium iodide, 0.05 M iodine, and 0.5 M 4-tert-Butylpyridine.

In the following experimental examples, the zinc oxide film obtained in the above Experimental Examples 1 to 9 was used as a photovoltaic element of a dye-sensitized solar cell, and a dye-sensitized solar cell was prepared and subjected to photoelectrochemical measurement, respectively. Further, the counter electrode of the above dye-sensitized solar cell is platinum; the electrolyte is an acetonitrile solution containing 0.5 M lithium iodide, 0.05 M iodine, and 0.5 M 4-tributylpyridine; the dye is N ₇₁₉ dye.

In the following experimental example, the test area is 0.25 cm ² , and the light source used is to simulate the illumination of sunlight under AM 1.5 conditions (temperature about 25 ° C, average illuminance of light 1000 W/m ² ) to obtain a photosensitized solar cell. The current-voltage characteristic curve (IV curve), and thereby know its photoelectric characteristics, such as short circuit current ( J sc), open circuit voltage ( V oc), fill factor (fill factor, FF And solar energy to electricity conversion efficiency (η).

Tables 2 to 7 list the photoelectrochemical test results of the dye-sensitized solar cells obtained in each of the experimental examples, and Tables 2 to 7 respectively discuss the effects of changing single parameters on the photoelectric characteristics of the dye-sensitized solar cells. The battery 1 indicates that the dye-sensitized solar cell system uses the zinc oxide film of the above Experimental Example 1 as a photoelectrode material, and the battery 3 indicates that the dye-sensitized solar cell system uses the zinc oxide film of the above Experimental Example 3 as a photoelectrode material, and the other The experimental methods are the same for each experimental example.

The data in Table 2 shows that the deposition time of the zinc oxide precursor film is thicker as the other parameters are the same, and the solar cell performance is also better. Specifically, the photoelectric characteristics such as the open circuit voltage, the short circuit current, the fill factor, and the photoelectric conversion efficiency of the battery 1 are superior to those of the battery 3.

It can be found from Table 3 that changing the sintering temperature also affects the performance of the dye-sensitized solar cell when the other parameters are the same. In the experimental examples shown in Table 3, the photoelectric conversion efficiency was the highest in the battery 2 (sintering temperature: about 300 ° C). Further, taking the battery 5 (sintering temperature about 450 ° C) as an example, although the sintering temperature is increased so that the open circuit voltage and the fill factor become high, the short-circuit current and the photoelectric conversion efficiency tend to decrease.

It can be found from Table 4 that when the other parameters are the same, the influence of the deposition potential change on the solar cell performance is quite obvious. When the deposition potential was changed from 1100 mV of the battery 2 to 900 mV of the battery 6, the photoelectric characteristics of the dye-sensitized solar cell such as open circuit voltage, short-circuit current, fill factor, and photoelectric conversion efficiency were significantly lowered.

It can be found from Table 5 that when other parameters are the same, the influence of the working distance on the performance of the solar cell is quite obvious. When the working distance is changed from 5 cm of the battery 3 to 2 cm of the battery 7, the photoelectric characteristics of the dye-sensitized solar cell such as open circuit voltage, short-circuit current, fill factor, and photoelectric conversion efficiency are remarkably improved.

According to Table 6, when the other parameters are the same, changing the concentration of the electrodeposition solution also affects the photoelectric characteristics of the dye-sensitized solar cell. When the concentration of zinc nitrate in the electrodeposition solution is changed from 1 M to 10 ^-1 M, although the open circuit voltage and the fill factor are only slightly changed, the short-circuit current and the photoelectric conversion efficiency are both reduced by more than 50%.

The data in Table 7 shows that the type of zinc oxide precursor also has an effect on the photoelectric properties of the dye-sensitized solar cell. The short-circuit current and photoelectric conversion efficiency of the zinc oxide film prepared by using zinc oxynitrate as a precursor are significantly better than those of zinc oxide film prepared by using zinc oxyhydroxide as a precursor.

In the above experimental examples, the relevant electrochemical parameters when preparing the zinc oxide thin film were adjusted, and the obtained zinc oxide thin film was used as the photoelectrode element to prepare a dye-sensitized solar cell. Although the results of the related embodiments show that changing the process parameters affects the photoelectric characteristics of the solar cell, the resulting dye-sensitized solar cell still has suitable photoelectric characteristics within the scope of the specific embodiments of the present invention. Industrial use.

While the present invention has been described above by way of a preferred embodiment, it is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

The above and other objects, features, advantages and embodiments of the present invention will become more <RTIgt; <RTIgt; </ RTI> <RTIgt; </ RTI> <RTIgt; X-ray diffraction pattern of the film.

Fig. 2 is a X-ray diffraction pattern of a zinc oxyhydroxide film and a zinc oxide film according to an embodiment of the present invention.

Claims (24)

A method for electrochemically preparing a zinc oxide film, comprising: preparing an electrodeposition solution comprising an aqueous zinc ion solution having a molar concentration of about 10 ^-1 M to about 1 M; and performing a coating on which a conductive substrate is placed Forming a zinc oxide precursor film on the conductive substrate in the electrodeposition solution at room temperature by using the following electrochemical parameters: a reference electrode is a silver/silver chloride electrode; a deposition potential of about 900-1100 mV; And a working distance of about 1-5 cm; drying the zinc oxide precursor film, wherein one of the drying temperatures used is about 15-40 ° C and a relative humidity of about 75% or more; and sintering the zinc oxide precursor film to obtain the The zinc oxide film comprises a first heating stage, a second heating stage and a cooling stage, wherein in the first heating stage, the temperature is raised from room temperature to about 100-150 ° C at a rate of about 2 ° C / minute and the temperature is constant. About 30-120 minutes; in the second temperature rising stage, the temperature is again raised to about 150-450 ° C at a rate of about 2 ° C / minute and the temperature is about 60-120 minutes; and in the cooling stage, about 2 ° C / The fractional rate is cooled to room temperature. The method for electrochemically preparing a zinc oxide film according to claim 1, wherein the electrodeposition solution comprises an aqueous zinc nitrate solution having a molar concentration of about 10 ^-1 M to about 1 M. Electrochemistry of a zinc oxide film as described in claim 2 The preparation method, wherein the zinc oxide precursor film formed is a zinc hydroxynitrate film. The method for electrochemically preparing a zinc oxide film according to claim 1, wherein the electrodeposition solution comprises an aqueous solution of zinc chloride having a molar concentration of about 10 ^-1 M to about 1 M. The method for electrochemically preparing a zinc oxide film according to claim 4, wherein the zinc oxide precursor film formed is a zinc hydroxychloride film. The method for electrochemically preparing a zinc oxide film according to claim 1, wherein the deposition potential is about 1100 mV. The electrochemical preparation method of the zinc oxide thin film according to claim 1, wherein a deposition time is about 100 to 300 minutes. The method for electrochemically preparing a zinc oxide film according to claim 7, wherein the deposition time is about 120 minutes. The method for electrochemically preparing a zinc oxide film according to claim 1, wherein the working distance is about 2 cm. The method for electrochemically preparing a zinc oxide film according to claim 1, wherein the drying temperature is about 30 °C. Electrochemical treatment of zinc oxide film as described in claim 1 The preparation method is wherein the relative humidity is about 80%. The method for electrochemically preparing a zinc oxide film according to claim 1, wherein the electrochemical parameter further comprises an operating temperature of about 23-27 °C. The method for electrochemically preparing a zinc oxide film according to claim 1, wherein the conductive substrate is a conductive fabric. The method for electrochemically preparing a zinc oxide film according to claim 1, wherein the conductive substrate is a transparent conductive substrate. The method for electrochemically preparing a zinc oxide film according to claim 14, wherein the transparent conductive substrate is made of fluorine-doped tin oxide/glass or indium tin oxide/polyethylene naphthalate. The method for electrochemically preparing a zinc oxide film according to claim 1, wherein the conductive substrate is a flexible substrate. The method for electrochemically preparing a zinc oxide film according to claim 16, wherein the material of the flexible substrate is polyethylene terephthalate, polyethylene naphthalate, polycarbonate or Polyamine. The method for electrochemically preparing a zinc oxide film according to claim 1, wherein the conductive substrate is a metal substrate. The method for electrochemically preparing a zinc oxide film according to claim 18, wherein the metal substrate is made of platinum or stainless steel. A photoelectrode element for a dye-sensitized solar cell, comprising: at least: a conductive substrate; and a zinc oxide film on a conductive surface of the conductive substrate, wherein the zinc oxide film is used as claimed in the patent scope The electrochemical preparation method of the zinc oxide thin film according to any one of items 1 to 19. The photoelectrode element of the dye-sensitized solar cell of claim 20, further comprising titanium oxide, tin oxide, copper oxide or zirconium oxide on the conductive surface of the conductive substrate. A dye-sensitized solar cell comprising at least: a photoelectrode element comprising at least one conductive substrate, and a zinc oxide film on a conductive surface of the conductive substrate, wherein the zinc oxide film is utilized as claimed The method for electrochemically preparing a zinc oxide thin film according to any one of the items 1 to 19, wherein a dye is adsorbed on the photoelectrode element; and a pair of electrodes having a conductive surface and the conductive base The conductive surface of the material is opposite; and an electrolyte is filled between the photoelectrode element and the pair of electrodes. The dye-sensitized solar cell of claim 22, wherein the electrolyte is an acetonitrile solution and comprises about 0.05 M of iodine and about 0.5 M of lithium iodide. The dye-sensitized solar cell of claim 22, wherein the photoelectrode element comprises titanium oxide, tin oxide, copper oxide or zirconium oxide on the conductive surface of the conductive substrate.