KR101802946B1 - Process for formation of metal oxide film on graphene - Google Patents

Abstract

There is provided a method for producing a metal oxide thin film on a graphene film which comprises depositing a graphene phase by ultrasonic spray pyrolysis using a solution in which a metal precursor compound is dissolved in a solvent, A high and transparent metal oxide thin film can be produced.

Description

[0001] The present invention relates to a method for manufacturing a metal oxide thin film on a graphene film,

More particularly, the present invention relates to a method of forming an oxide film, and more particularly, to a method for forming a metal oxide thin film on a graphene film, To form a homogeneous metal oxide.

Graphene, a single layer formed of a two-dimensional honeycomb crystal structure of carbon atoms, has recently been characterized by significant electronic, optical, chemical and mechanical properties, including quantum electronic transport, optical transparency, chemical stability and mechanical durability Have attracted attention in nanoscale functional devices and the like.

Graphene is one of the most promising next-generation transparent conductive materials to replace conventional transparent conductive oxides (TCO) such as indium tin oxide (ITO) and fluoro-tin oxide (FTO) in optoelectronic devices including solar cells and light emitting diodes Lt; / RTI >

In order to form the graphene into such a device, a step of forming a metal oxide thin film on the graphene is required. However, since graphene is hydrophobic and metal oxide is hydrophilic, it is difficult to form a thin film of metal oxide which is hydrophilic on hydrophobic graphene.

Including atomic layer deposition (ALD) using a sol-gel method, an aqueous solution method, a metalorganic chemical vapor deposition (CVD), a sputtering method, and a plasma surface treatment, a seeding layer or an interfacially self- Efforts have been made to produce high quality metal oxide thin films such as ZnO, TiO _x , aluminum oxide, hafnium oxide thin films or nanostructures on graphene using a variety of methods. However, problems such as inhomogeneous deposition of the metal oxide and weak contact between the metal oxide and the graphene have not yet been solved, due to the damage of the graphene by the plasma, the hydrophobic and chemically inert nature of the graphene.

For example, when a method of coating a graphene layer with an organic material to improve the adhesion between a metal oxide thin film and graphene or a method of forming a metal oxide thin film by an ALD method after treating the graphene layer with ozone, The presence of a foreign substance such as a material may reduce the electrical properties, or part of the graphene may be oxidized during ozone treatment. In addition, the ALD process is time-consuming, costly and not economical, and has limitations on the size of graphene that can be processed.

A first object of the present invention is to provide a method for producing a uniform metal oxide thin film on a graphene film at a relatively low temperature without damaging the graphene.

A second problem to be solved by the present invention is to provide a device comprising the metal oxide thin film on the graphene produced by the above method.

To achieve the first object, according to an aspect of the present invention,

Dissolving the metal precursor compound in a solvent to obtain a metal precursor solution;

Ultrasonicing the metal precursor solution to obtain a mist in which the metal oxide precursor is dispersed in a solvent; And

Feeding the droplet into a chamber containing graphene by a carrier gas and adsorbing it on the graphene

A method for producing a thin metal oxide film on a graphene film is provided.

According to an embodiment of the present invention, the metal precursor compound may be at least one selected from the group consisting of acetate, chloride, nitrate, and acetic anhydride of the metal.

According to another embodiment of the present invention, the solvent may be water or a low boiling point solvent.

According to another embodiment of the present invention, the metal precursor compound may be a precursor compound of at least one metal selected from zinc, copper, aluminum, tin and magnesium.

According to another aspect of the present invention to achieve the second object,

Board; Graphene formed on the substrate; And a metal oxide thin film formed on the graphene, wherein the metal oxide thin film is provided with an element manufactured by the above manufacturing method.

According to an embodiment of the present invention, the element may be a transparent energy generation element or a transparent photoelectric element.

According to the manufacturing method of the present invention, the metal oxide thin film having excellent crystallinity and conductivity can be manufactured at a relatively low temperature without temperature limitation without damaging graphene.

FIG. 1 is a schematic view showing a step of growing a ZnO thin film on a graphene by a manufacturing method according to an embodiment of the present invention.
2 is a field emission scanning electron microscope (FE-SEM) photograph of the ZnO thin film prepared in Example 1 and Comparative Examples 1 and 2 of the present invention.
3 is a transmission electron microscope (TEM) photograph of the ZnO thin films prepared in Example 2 and Comparative Example 3 of the present invention.
4 is a graph of Raman spectrum and sheet resistance of the ZnO thin films prepared in Example 2 and Comparative Example 3 of the present invention.
5 is a graph showing the transmittance of the graphene and ZnO thin films of Example 1. Fig.
6 is a graph showing the result of synchrotron X-ray diffraction (Syncrotron XRD) of the ZnO thin film obtained in Example 1. Fig.
FIGS. 7A and 7B are schematic diagrams and energy level diagrams of the IOSC including the ZnO thin film obtained in Example 1. FIG.
8A and 8B are graphs showing JV characteristics of BHJ IOSC including flexible BHJ IOSC including the ZnO thin film obtained in Example 1 and conventional ITO electrodes at the time of AM 1.5G irradiation and in the dark.

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

A method of manufacturing a metal oxide thin film according to an embodiment of the present invention includes:

Dissolving the metal precursor compound in a solvent to obtain a metal precursor solution; Ultrasonically treating the metal precursor solution to obtain a droplet in which the metal oxide precursor is dispersed in a solvent; Supplying the droplet into a chamber containing graphene by a carrier gas, and adsorbing the droplet onto the graphene.

According to one embodiment of the present invention, a metal oxide thin film having excellent interface characteristics on a substrate, for example, a graft formed on a flexible plastic substrate, can be successfully grown directly. That is, at a low growth temperature, for example, at a low temperature of 160 DEG C, the metal is oxidized by a non-vacuum process by Mist Pyrolysis Chemical Vapor Deposition (MPCVD), without causing thermal, structural or electrical damage to the graphene layer To grow the thin film.

The metal precursor compound used for preparing the metal oxide thin film according to an embodiment of the present invention may be at least one selected from the group consisting of acetate, chloride, nitrate and acetic anhydride of the metal. The metal precursor compound may be a precursor compound of at least one metal selected from the group consisting of zinc, copper, aluminum, tin, and magnesium. The metal precursor compound can be used without limitation as long as it can finally react with oxygen to form a desired metal oxide thin film. In particular, zinc acetate is not limited to a solvent and can be easily used because it enables high-quality thin film deposition at a lower temperature.

As the solvent for preparing the solution of the metal precursor compound, water or a low boiling point solvent may be used. The low boiling point solvent may be at least one selected from acetone, methanol and ethanol. By using the low boiling point solvent, ultimately, the metal oxide can be adsorbed at a relatively low temperature upon pyrolysis.

The metal precursor compound may be used in an amount of 1 to 50 parts by weight based on 100 parts by weight of the solvent. If it is within the above range, the metal precursor can be completely dissolved in the solvent.

The metal precursor solution is subjected to ultrasonic treatment to obtain a droplet in which the metal oxide precursor is dispersed.

The diameter of the droplet may be 3 to 1.8 탆. When the particle size of the droplet is within the above range, the carrier gas can be easily transported to the chamber and the adsorption on the graphene can be facilitated. The metal precursor compound in the droplet solvent exists in an ionized state.

The graphene on which the droplets are adsorbed is located in the chamber and is typically formed on the substrate.

The metal oxide precursor droplet is supplied to the chamber in which the graphene is present as the carrier gas.

The carrier gas may be oxygen or an inert gas such as nitrogen or argon, and may be used at a flow rate of 10 to 20000 sccm.

A droplet containing the metal oxide precursor supplied to the chamber in which the graphen is present is adsorbed on the graphene and a metal oxide thin film is formed by pyrolysis.

The principle of formation of the metal oxide thin film will be described below taking the case of using acetone as a low boiling point solvent. This is for illustrative purposes only, and the invention is not limited thereby.

Zn ion derived from a droplet of a metal precursor compound, for example, zinc acetate, is adsorbed to the graphene phase in the form of ZnO in the following manner.

First, after dissolving zinc acetate in a solvent and sonication, it is present in the following state:

_{4Zn (CH 3 COO) 2 (} g) -> 4Zn 2 + + 8CH 3 COO - (1)

Here, "g" means gas state.

The droplets are fed to the chamber with graphene by carrier gas, where a pyrolysis process takes place. The ZnO thin film grows in a continuous process with decomposition of zinc acetate:

CH ₃ COCH ₃ (g) + 4O ₂ (g) -> 3CO ₂ (g) + 3H ₂ O (g)

H ₂ O (g) -> H ⁺ + OH ^- (3)

CH ₃ COO ^- + H ⁺ -> CH ₃ COOH (g) (4)

Zn ^{2 +} + OH ^- -> ZnO + H ₂ O (5)

Acetone is very important for the growth of ZnO thin films and acts as a raw material for the provision of additional oxygen ions as well as solvents. When acetone is heated, H ₂ O is released from the combustion reaction due to O ₂ in air, and it is expected to improve the physical properties of ZnO crystals due to the presence of H ₂ O during the growth of the ZnO thin film

The graphene may be formed on the substrate. The substrate may be a transparent glass substrate, a plastic substrate, or the like, but may be a flexible plastic substrate such as polyethylene naphthalate (PEN), polyethersulfone (PES), and the like.

For example, a carbon source may be chemically deposited on a metal foil used as a graphitizing catalyst, and then a graphitizing catalyst may be used to transport the graphene to the substrate. A polymer such as PMMA is spin-coated on the graphene opposite to the surface on which the grains are formed. Then the etchant is removed using an etchant, the graphene on the PMMA is transferred onto the PEN substrate, and the PMMA is then removed using a solvent.

In the graphene formation process, carbon can be supplied as a carbon source, and any material that can be present in a gaseous phase at a temperature of 300 ° C or higher can be used without any particular limitation. The gaseous carbon source may be a compound containing carbon, more preferably a compound having a carbon number of 6 or less, more preferably a compound having a carbon number of 4 or less, and still more preferably a compound having a carbon number of 2 or less. Examples thereof include at least one selected from the group consisting of carbon monoxide, methane, ethane, ethylene, ethanol, acetylene, propane, propylene, butane, butadiene, pentane, pentene, cyclopentadiene, hexane, cyclohexane, benzene and toluene.

Such a carbon source may be introduced into the chamber where the graphitizing catalyst is present at a constant pressure. In the chamber, the carbon source alone may be present, or may be present together with an inert gas such as helium, argon, or the like.

Hydrogen may be used in addition to the carbon source. Hydrogen can be used to keep the surface of the metal catalyst clean to control the gas phase reaction, and is 5 to 40% by volume of the total volume of the vessel, for example, 10 to 30% by volume, or 15 to 25% by volume.

After the carbon source is introduced into the chamber in which the graphitizing catalyst is present, the graphene is formed on the surface of the graphitizing catalyst by heat treatment at a predetermined temperature. The heat treatment is performed so as to maintain the film shape of the graphitizing catalyst. The heat treatment temperature serves as an important factor in the production of graphene, and may be, for example, 300 to 2000 占 폚, or 500 to 1500 占 폚. When the heat treatment temperature is within the above range, sheet-like graphene can be effectively obtained.

It is possible to control the degree of formation of graphene by maintaining the above-mentioned heat treatment at a predetermined temperature for a predetermined time. That is, when the heat treatment process is maintained for a long time, the number of graphenes formed increases, so that the thickness of the resulting graphene can be increased. If the heat treatment process is shorter than that, the resulting graphene thickness is reduced. Therefore, in order to obtain the desired graphene thickness, the holding time of the heat treatment process may be an important factor in addition to the type of the carbon source, the supply pressure, the type of the graphitizing catalyst, and the size of the chamber. The holding time of such a heat treatment process can be generally maintained for 0.001 to 1000 hours, and if desired, the desired graphene can be effectively obtained.

As the heat source for the heat treatment, induction heating, radiation heat, laser, IR, microwave, plasma, UV, surface plasmon heating and the like can be used without limitation. Such a heat source is attached to the chamber and functions to raise the temperature inside the chamber to a predetermined temperature.

After the heat treatment as described above, the heat treatment result is subjected to a predetermined cooling process. Such a cooling process is a process for uniformly growing the graphene so that it can be uniformly arranged. Rapid cooling may cause cracks or the like of the generated graphene. Therefore, it is preferable to cool gradually at a constant rate For example, at a rate of 10 to 100 ° C per minute, and it is also possible to use a method such as natural cooling. The natural cooling is obtained by simply removing the heat source used for the heat treatment, and it becomes possible to obtain a sufficient cooling rate even by removing the heat source.

The graphene obtained after such a cooling step can have a thickness ranging from one layer to about 300 layers, for example, from 1 to 60 layers, or from 1 to 15 layers.

The heat treatment and cooling process as described above can be performed in one cycle, but it is possible to produce graphene having a dense structure with a high number of layers by repeating these processes several times.

The step of adsorbing droplets containing a metal oxide precursor on the graphene can be performed at a temperature of 350 DEG C or less, for example, a temperature of 50 DEG C to 200 DEG C, 80 DEG C to 160 DEG C, and an air atmosphere. In the manufacturing method according to an embodiment of the present invention, metal oxide is adsorbed in an air atmosphere at a relatively low temperature, so that damage to graphene is small and a metal oxide thin film can be easily formed. It is also possible to process directly on a plastic substrate since low temperatures are possible.

Thin film thickness and other properties in the spin coating of metal oxides depend primarily on the balance between the centrifugal force controlled by the spin rate and the viscous force determined by the viscosity of the solvent and the substrate wettability. Since the graphene surface is weakly wettable (i.e., hydrophobic), the metal oxide thin film formed by the sol-gel method has a surface with a polka-type point.

On the other hand, in the manufacturing method according to an embodiment of the present invention, the growth of the metal oxide thin film is based on a chemical reaction that occurs after the metal oxide precursor is adsorbed on the substrate. Therefore, the nucleation and growth of the thin film are mainly determined by the growth temperature and the crystal structure of the substrate, rather than the surface wettability. Nucleation of the metal oxide at low temperature is more active than at high temperature while the surface diffusion length of the atoms adsorbed to the graphene phase due to the low growth temperature is short and the non-epitaxial graphene substrate RTI ID = 0.0 > irregularly < / RTI > oriented metal oxide nuclei. In some orientations, cluster growth occurs from irregularly arranged nuclei initially due to additional growth. The preferred orientation of the cluster is only determined by the preferred orientation of the initial nuclei at this stage. The cluster morphology is transformed into a surface with a nanoscale texture as the metal oxide grows. The Volmer-Weber growth mode forms a textured surface morphology when the adsorption atom-adatom-adatom interaction is much stronger than the adsorption atom-substrate surface interaction.

FIG. 1 is a schematic view showing a step of growing a ZnO thin film on a graphene by a manufacturing method according to an embodiment of the present invention according to a Bolmer-Weber growth mode.

First, nuclei are formed by irregular orientation (FIG. 1A), nuclei formed continuously (FIG. 1B), growth proceeds in a preferred orientation (FIG. 1C), and thin films are formed in the Bolmer- 1d).

According to another embodiment of the present invention, there is provided a semiconductor device comprising: a substrate; Graphene formed on the substrate; And a metal oxide thin film formed on the graphene, wherein the metal oxide thin film can be produced by the above-described method.

The graphene layer may have 1 to 100 layers, and the metal oxide layer may have a thickness of 10 nm to 1 탆.

Examples of the device include a transparent energy generation device or a transparent photoelectric device, and an inverted organic solar cell.

Organic solar cells (OSC) based on graphene grown by chemical vapor deposition (CVD) of high performance (less than about 2.5% conversion) have recently been reported. However, OSC based on CVD grown graphene anodes, including semiconducting polymer / fullerene bulk heterojunction (BHJ) blends, were fabricated on glass substrates rather than plastic substrates, and the practical flexibility of the BHJ OSCs made with graphene electrodes There was no report. Furthermore, the BHJ OSC based on conventional graphene anodes has a hygroscopic acidic poly (3,4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT: PSS) layer and a low- As a result of including the metallic cathode of the function (e.g., Al, Ca), the BHJ layer and the cathode have a significant impact on the stability of the OSC.

Inverted organic solar cells have been intensively studied due to their high latency interfacial stability, which replaces low work-function metal cathodes with air-stable, high work function metal anodes (e.g., Au, Ag) And introducing an n-type metal oxide semiconductor as a preferable path capable of effectively transporting electrons from the polymer layer to the cathode electrode.

Until now, due to technical difficulties associated with the direct growth of a high quality n-type metal oxide semiconductor such as zinc oxide (ZnO) titanium oxide (TiO _x ) and cesium carbonate (Cs ₂ CO ₃ ) on a graphen / Flexible BHJ IOSCs based on graphene cathodes have not been reported. The flexible IOSC can be easily manufactured by using the graphene cathode including the metal oxide thin film manufactured by the manufacturing method according to one embodiment of the present invention.

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

Example 1

Fabrication of graphene sheets on substrates

Cu foil (purchased from Alpha Asher thickness: 125 占 퐉) was placed in a self-made heated CVD chamber and heated at 1000 占 폚 for 30 minutes using a halogen lamp heat source while constantly introducing hydrogen gas at 200 sccm into the chamber . And a mixed gas of CH _{4 20} sccm / H _{2 4} sccm was added to the chamber for 30 minutes. The chamber was then slowly cooled to grow graphene uniformly to form a graphene monolayer having a thickness of 10 mm x 10 mm with a thickness of one layer.

Subsequently, to separate the graphene from the Cu foil, a solution of chlorobenzene (5 wt%) in which PMMA was dissolved on a graphene / Cu foil was coated at a rate of 1,000 rpm for 60 seconds, and the resultant was subjected to Cu etch (FeCl ₃ ) Solution (Transene type 1). And the Cu foil was removed by immersing for 1 hour to separate the graphene attached to the PMMA. The graphene attached to the PMMA was transferred to a sheet of polyethylene naphthalate (PEN, DPont Teijin), dried, and then PMMA was removed with acetone. This transferring step was repeated three times to obtain a graphene 3 layer.

Formation of ZnO Thin Films on Graphene / PEN

The raw material solution for ZnO thin film growth was prepared by dissolving 0.01 M zinc acetate in acetone (100 mL). The raw material solution was ultrasonicated to form a mist to form a ZnO precursor, which was supplied into a chamber containing the graphene by a nitrogen carrier gas of 5000 sccm and adsorbed on the graphene. At this time, the temperature of the chamber was maintained at 160 캜 to form a 70 nm thick ZnO thin film on the graphene phase.

Comparative Example 1: ZnO thin film formation on graphene / PEN by sol-gel method

Zinc acetate anhydride (Zn (CH ₃ COO) ₂ .2H ₂ O, 0.05M) was dissolved in methoxyethanol (C ₃ H ₈ O ₂ , 9.56 ml) and monoethanolamine (C ₂ H ₇ NO, 0.44 ml) To form a ZnO sol. The ZnO sol was spin-coated at 4000 rpm for 30 seconds, adhered onto graphene / PEN prepared in the same manner as in Example 1, and heated at 150 ° C for 30 minutes to form a ZnO thin film.

Comparative Example 2: ZnO thin film formation on graphene / PEN film by sputtering

ZnO was deposited on a graphene / PEN prepared by the same method as in Example 1 from a commercially available ZnO target in an Ar / O ₂ (29: 0.1 gas ratio) atmosphere by a radio frequency (RF) magnetron sputtering system. The deposition temperature and the chamber pressure of the ZnO thin film were 100 캜 and 3 mTorr, respectively. RF power was maintained at 150 W for 16 minutes to attach a thickness of about 60 nm.

Example 2

A ZnO thin film was formed on the graphene / SiO ₂ layer in the same manner as in Example 1, except that a SiO ₂ / Si substrate was used in place of the PEN substrate and the number of graphene layers was six.

Comparative Example 3: ZnO thin film formation on graphene / SiO ₂ by sputtering

A ZnO thin film was formed on the graphene / SiO ₂ layer in the same manner as in Comparative Example 2, except that the SiO ₂ substrate was used instead of the PEN substrate and the number of graphene layers was changed to six.

FIG. 2 is an electroluminescence scanning electron microscope (FE-SEM) photograph of a ZnO thin film formed on a graphene / PEN substrate prepared according to Example 1 and Comparative Examples 1 and 2.

In the high temperature CVD growth and graphene transfer process of graphene, some graphene wrinkles were formed as shown in FIG. 2A, but an atomically flat graphene surface was obtained. The ZnO thin film formed using the sol-gel method of Comparative Example 1 had a pointed and porous surface (Fig. 2B). The ZnO thin film formed by the sputtering method of Comparative Example 2 was deteriorated in adhesiveness to graphene due to plasma damage, resulting in cracking and showing the peeled ZnO surface (FIG. 2C).

On the other hand, the ZnO thin film formed according to Example 1 exhibited uniformity over a large area of the graphene 3 layer / PEN, even though the ZnO thin film of the surface morphology having the nanoscale texture, despite the hydrophobicity and the chemical inertness characteristic of graphene, (Fig. 2D).

FIG. 3 is a TEM (JEM 2100F, JEOL) of a ZnO thin film formed according to Example 2 and Comparative Example 3.

According to Example 2, a 70 nm thick ZnO thin film with polycrystalline properties successfully grown on graphene (Fig. 3A). The graphene sheet was slightly damaged during the production of the TEM sample, but the crystal lattice of the graphene sheet according to Example 2 was observed with a high-resolution transmission electron microscope (HR-TEM) as shown in Fig. 3B. In contrast, as shown in FIG. 3C, the graphene sheet was completely damaged in Comparative Example 3, and the amorphous phase was formed on the graphene surface when the ZnO thin film was formed by the sputtering method. 3D and 3E are fast Fourier transform (FFT) patterns corresponding to the areas indicated by P1 in FIG. 3B and P2 in FIG. 3C, respectively. From this, it can be confirmed that the ZnO thin film according to Example 2 is a crystalline phase and the ZnO thin film according to Comparative Example 3 is an amorphous phase.

Fig. 4 shows a Raman spectrum of the ZnO thin film obtained in Example 2 and Comparative Example 3 (Reinshaw, RM-1000 Invia at 514 nm). In the Raman spectra of the completely new graphene layer as shown in Fig. 4A, distinct G- and 2D-peaks were observed at 1580 cm ^-1 and 2700 cm ^-1 , respectively. On the other hand, in the case of the ZnO thin film of Comparative Example 3 formed by the sputtering method, the intensity of the D-peak at 1350 cm ^-1 significantly increased, while the intensity of the G-peak and 2D-peak decreased significantly. The peak intensity ratio (I _D / I _G ) in the ZnO thin film formed by the sputtering method was obviously increased compared to the peak intensity ratio in the ZnO thin film formed by the manufacturing method of Example 2 of the present invention, Indicating severe structural damage to the pin. Graphene damage during the process was additionally confirmed in the Hall effect measurement at room temperature (ACCENT semiconductor UK / HL 5500PC) based on the Van der Pauw configuration (FIG. 4B). 4B, there was a slight change in the surface resistance of the ZnO thin film obtained in Example 2 (409? / Sq at 278? / Sq), while in the sheet resistance of the graphene after ZnO deposition using the sputtering method of Comparative Example 3, A dramatic increase was observed (1887? / Sq at 278? / Sq). Therefore, it can be confirmed that the method of manufacturing a metal oxide thin film according to an embodiment of the present invention does not damage the graphene layer.

5 is a graph showing the transmittance of ZnO / graphene on the graphene and PEN substrate on the PEN substrate obtained in Example 1 according to the wavelengths. As shown in FIG. 5, the graphene 3 layer / PEN sample showed a transmittance of about 82.6% at a wavelength of 550 nm, and the 70 nm thick ZnO thin film / graphene 3 layer / PEN sample showed a high transmittance of 78.9% Which means that there was no significant change in the transmittance during ZnO growth.

6 is a graph showing the result of synchrotron X-ray diffraction (Syncrotron XRD) of the ZnO thin film obtained in Example 1. Fig.

The scan was performed in reciprocal space with respect to the surface direction, that is, Qz [Q = 4? Sin (2? / 2) /?]. As shown in FIG. 6, the (002) reflection peak associated with the wurtzite structure of ZnO was clearly detected at a Qz value of 2.406 는데, and its peak was weak and broad. However, graphene-related peaks were not observed in synchrotron XRD measurements because graphene was extremely thin.

Fabrication of Flexible Bulk Heterojunction Inverted Organic Solar Cell (BHJ IOSC)

A polymer blend of poly (3-hexylthiophene): [6,6] -phenyl-C61-butyric acid methyl ester (P3HT: PCBM 1: 1 by weight) in a chlorobenzene solvent (150 ml) Lt; / RTI > The above solution was spin-coated on the ZnO thin film (electron transporting layer, 70 nm) / graphene (lower cathode) / PEN (or SiO ₂ ) prepared in the above Examples and Comparative Examples at 900 rpm to obtain an active layer with a thickness of 180 nm. The active layer was annealed in a hot plate at 110 DEG C for 10 minutes. The MoO ₃ electron blocking layer and the Ag anode were continuously deposited by thermal evaporation to a thickness of 20 nm and 80 nm, respectively, to prepare IOSC corresponding to each of Examples and Comparative Examples.

FIGS. 7A and 7B show schematic diagrams and energy level diagrams of IOSC including the ZnO thin film obtained in Example 1. FIG.

Current density-voltage (JV) measurements were performed using a solar simulator under standard AM 1.5G solar irradiation. 8A and 8B show JV characteristics of BHJ IOSC including flexible BHJ IOSC including the ZnO thin film obtained in Example 1 and conventional ITO electrode at the time of AM 1.5G irradiation and in the dark. The JV characteristics of the flexible BHJ IOSC including the ZnO thin film obtained in Example 1 showed a remarkable diode behavior and the short circuit current (Jsc), the charge factor (FF), the open circuit current (VOC) Showed 6.62 mA / cm ² , 46.59%, 0.50 V, and 1.55%, respectively. These values are slightly smaller than the values of the flexible IOSC based on commercially available ITO (JSC of 7.50 mA / cm ² , FF of 57.77%, VOC of 0.52 V, and PCE of 2.25%) but based on graphene anodes on glass substrates It is comparable to BHJ OSC.

The metal oxide thin films grown by the method according to one embodiment of the present invention exhibit a uniform morphology and exhibit higher crystallinity, higher electrical conductivity, and higher transparency than the thin films deposited using the sol-gel method and the sputtering method.

Claims (14)

Dissolving the metal precursor compound in a solvent to obtain a metal precursor solution;
Ultrasonically treating the metal precursor solution to obtain a droplet in which the metal oxide precursor is dispersed in a solvent;
Feeding the droplet into a chamber containing graphene by a carrier gas and adsorbing the droplet onto the graphene,
The solvent is water or a low boiling solvent,
Wherein the low boiling point solvent is at least one selected from acetone, ethanol and methanol,
A method for producing a thin metal oxide film on a graphene film. The method according to claim 1,
Wherein the metal precursor compound is at least one selected from the group consisting of an acetate, a chloride, a nitrate, and an acetic anhydride of a metal. The method according to claim 1,
Wherein the metal precursor compound is a precursor compound of at least one metal selected from the group consisting of zinc, copper, aluminum, tin, and magnesium. delete delete The method according to claim 1,
Wherein the graphene is formed on a substrate. The method according to claim 6,
Wherein the substrate is transparent polyethylene naphthalate (PEN) or a SiO ₂ substrate. The method according to claim 1,
Wherein the adsorption step is carried out at a temperature of 350 DEG C or less and in an air atmosphere. The method according to claim 1,
Wherein the carrier gas is nitrogen or argon and the flow rate is 100 to 5000 sccm. Board;
Graphene formed on the substrate; And
And a metal oxide thin film formed on the graphene,
Wherein the metal oxide thin film is a metal oxide thin film produced by the manufacturing method according to any one of claims 1 to 3 and 6 to 9. 11. The method of claim 10,
Wherein the graphene comprises 1 to 100 layers. 11. The method of claim 10,
Wherein the metal oxide thin film has a thickness of 10 nm to 1 占 퐉. 11. The method of claim 10,
Wherein the element is a transparent energy generation element or a transparent photoelectric element. 11. The method of claim 10,
Wherein the device is an inverted organic solar cell.

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