KR101470816B1 - Photovoltaic cell comprising nano-particle layer and method for producing the same - Google Patents

Abstract

The present invention relates to a solar cell in which a contact surface is maximized by forming a nanoparticle layer composed of a plurality of nanoparticles by arranging nanoparticles made of a p-type material including a photosensitive structure and a functional group on a substrate and electrodes, .

Description

TECHNICAL FIELD The present invention relates to a solar cell including a nanoparticle layer and a method of manufacturing the same.

The present invention relates to a solar cell having a nanoparticle layer composed of a plurality of nanoparticles by arranging nanoparticles containing a photosensitive structure and a functional group to maximize a contact surface, and a method for manufacturing the same.

Nanotechnology is a technology that identifies and controls materials at both molecular and atomic levels. It is a technology that enables modification and modification of existing materials and creation of new materials by properly combining atoms and molecules. Based technology.

Nanomaterials are materials that usually have sizes ranging from a few nanometers to a few micrometers and exhibit new electronic, magnetic, optical, and electrical properties that are not visible in the bulk solid state. Due to these properties, studies on the production of nanomaterials using metals, metal oxides, and inorganic materials have been continuously conducted. As a result, the technology for manufacturing nanometer-sized metals, inorganic semiconductor nanoparticles and organic polymer nanomaterials has been well established Industrial applications are actively researched.

Control of particle size in nanometer increments significantly increases material performance due to increased surface area. More specifically, when the size of a solid crystal is in the region of a few nanometers, its size can be a parameter that determines the chemical and physical properties of the crystal. Such nanotechnology research is now being actively conducted worldwide. Nanoparticles having a size of several nanometers exhibit a unique behavior, and it is known that they can be utilized for a semiconductor structure for creating a high-efficiency light emitting device and an emission mark of a molecule in a living body.

As a manufacturing process of nanoparticles, methods of controlling the size of nanoparticles by introducing an emulsifier or a derivative of a monomer into a solvent have been widely tried. In detail, by controlling the growth of the solvent phase stabilizer in the growth of the nanoparticles on the surface of the nanoparticles, the nanoparticles of various sizes can be synthesized by controlling the concentration of the monomer used, the type of the organic solvent, can do.

Korean Patent Registration No. 1012565 discloses a first nanowire layer for transferring holes to a lower electrode; A nanoparticle layer formed on the first nanowire layer to form electron-hole pairs by the incidence of sunlight; And a second nanowire layer formed on the nanoparticle layer and configured to transfer holes formed in the nanoparticle layer to an upper electrode. This patent discloses nanoparticle layers and nanowire layers, which are composed of inorganic nanoparticles.

Korean Patent Laid-Open Publication No. 2009-65175 discloses a semiconductor device comprising a semiconductor electrode and an opposite electrode which are opposed to each other and an electrolyte solution interposed therebetween, the semiconductor electrode comprising: a conductive substrate; A nanorod-nanoparticle complex formed on the conductive substrate; And a dye adsorbed on the surface of the nanoparticles. This patent also discloses nanorods and nanoparticles, but the nanoparticles consist of inorganic nanoparticles.

Korean Patent No. 1036453 discloses a semiconductor layer made of a semiconductor material; And a semiconductor structure formed of a semiconductor nanowire including a core-nanowire formed of an intrinsic semiconductor material and formed in a shape extending upward above the semiconductor layer and a cell-nanowire formed to surround an outer portion of the core- Wherein the semiconductor material forming the semiconductor layer is a p-type, and the semiconductor material forming the semiconductor layer is a p-type, wherein the semiconductor material forming the semiconductor layer is n- And the semiconductor material constituting the nanowire is n-type. This patent also discloses nanowires and nanoparticles, but the nanoparticles consist of inorganic nanoparticles.

As described above, there are prior art disclosing nanolayers comprising nanoparticles, nanorods and / or nanowires, but the nanoparticles of the prior art are composed of inorganic nanoparticles.

The present invention relates to a method for increasing efficiency of a conventional solar cell, and an object of the present invention is to arrange nanoparticles made of a p-type organic material including a photosensitive structure and a functional group on a substrate and electrodes, And a method for manufacturing the same.

In order to achieve the above object, the present invention provides a solar cell comprising a nanoparticle layer formed by arranging a plurality of nanoparticles including a p-type organic material.

In the present invention, the p-type organic material is a conductive polymer containing a photosensitive structure and a functional group. The conductive polymer may include p-phenylenevinylene, fluorene, carbazole, thiophene, poly (aryleneethynylene) , Phenothiazine, fluorenone, porphyrin, and derivatives thereof, and the repeating unit may be a repeating unit selected from the group consisting of alkyl, alkoxy, carboxyl, sulfone, and alkyleneoxy And may be substituted with one or more substituents selected.

In the present invention, the size of the nanoparticles may be 10 to 100 nm, and the polydispersity index (PDI) of the nanoparticles may be 1 to 10.

In the present invention, the nanoparticle layer may be composed of two or more layers.

In the present invention, an electron transport layer containing an n-type material may be formed on the nanoparticle layer to form a p-n junction, and the n-type material may be filled between the pores of the nanoparticle layer.

In the present invention, the n-type material may be one selected from the group consisting of fullerene (C ₆₀ ), fullerene (C ₇₀ ), 6,6-phenyl-C61-butyric acid methyl ester and 6,6- Or more.

In the present invention, a hole transporting layer may be formed under the nanoparticle layer, and the hole transporting layer may be formed of poly (3-alkylthiophene), poly (3,4-ethylenedioxythiophene) Polyaniline, and polyaniline.

In the present invention, a first electrode may be formed under the hole transport layer, and a second electrode may be formed on the electron transport layer.

The present invention also provides a method of manufacturing a solar cell comprising applying a solution containing a plurality of nanoparticles containing a p-type organic material to form a nanoparticle layer.

A method of manufacturing a solar cell according to the present invention includes the steps of: forming a hole transport layer on a first electrode; Forming a nanoparticle layer on the hole transport layer; Impregnating a solution containing an n-type material on the nanoparticle layer to form an electron transport layer; And forming a second electrode on the electron transport layer.

In the production method of the present invention, the content of the nanoparticles in the solution containing the plurality of nanoparticles may be 0.01 to 50% by weight based on the total weight of the solution.

In the production method of the present invention, the solution containing the plurality of nanoparticles may comprise a mixture of water or a polar solvent.

In the production method of the present invention, the application of the solution containing the nanoparticles may be carried out by one or more methods selected from screen printing, spin coating, drop casting, bar coating, gravure coating, blade coating, spray coating, roll coating, . ≪ / RTI >

In the manufacturing method of the present invention, the step of applying a solution containing a plurality of nanoparticles containing the p-type organic material to form a nanoparticle layer may be repeated one or more times to form a nanoparticle layer of two or more layers.

In the production method of the present invention, the solution containing the n-type material includes at least one solvent selected from chloroform, tetrahydrofuran, chlorobenzene, dichlorobenzene, toluene, dichloromethane, trichlorethylene, and xylene .

In the manufacturing method of the present invention, the impregnation of the solution containing the n-type material can be performed by one or more methods selected from spin coating, spray coating, and dip coating.

In the present invention, by impregnating the solution containing the n-type material, the n-type material can be filled between the pores of the nanoparticle layer to form a p-n junction.

In the manufacturing method of the present invention, spin coating may be performed in the step of forming the hole transporting layer, followed by heat treatment at a temperature of 100 to 150 ° C in a vacuum state.

In the present invention, the hole transport layer of a conventional heterogeneous junction structure is arranged in a nanoparticle including a photosensitive structure and a functional group, so that the disadvantage of the organic solar cell such as the isolation phenomenon of the hole transport layer of the heterojunction structure or the surface area in a narrow range Can be minimized, and the particle size can be adjusted to absorb a broader wavelength band of sunlight, thereby absorbing more sunlight at the same light amount.

1 is a cross-sectional view of a solar cell according to an embodiment of the present invention.
Fig. 2 is an enlarged view of the main part of Fig.
3 is a process flow diagram of a solar cell according to FIG.
FIGS. 4 and 5 are scanning electron micrographs of a conductive nanoparticle-containing composition applied to form a p-type nanoparticle layer according to an embodiment of the present invention. As the particle size is controlled, nanoparticles having different sizes , Which are stacked and arranged in water layers.
6 is a UV-Vis spectrum of P3HT [poly (3-hexylthiophene)] nanoparticles applied to form a p-type nanoparticle layer according to an embodiment of the present invention.
7 shows a photoluminescence spectrum of P3HT nanoparticles applied to form a p-type nanoparticle layer according to an embodiment of the present invention, and a photoluminescence spectrum of an electron-conducting n-type semiconductor layer material Is a photoluminescence spectrum after impregnating PCBM with PCBM to fill pores in the p-type nanoparticle layer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a photoresponsive solar cell of the present invention and a method of manufacturing the same will be described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification. Therefore, the present invention is not limited to the accompanying drawings but may be embodied in other forms, and the attached drawings may be exaggerated to clarify the meaning of the present invention. It is also to be understood that the same reference numerals denote like elements throughout the specification and, unless otherwise defined in the technical and scientific terms used, the meaning commonly understood by one of ordinary skill in the art to which this invention belongs I have.

FIG. 1 is a sectional view of a solar cell according to an embodiment of the present invention. The solar cell according to this embodiment includes a second electrode 10, an electron transfer layer 20, a nanoparticle layer 30, A transfer layer 40, a first electrode 50, and a substrate 60.

The second electrode 10 may be a cathode as the upper electrode and may be formed of a metal such as aluminum.

The electron transporting layer 20 may comprise an n-type material. Examples of the n-type material include fullerene (C ₆₀ ), fullerene (C ₇₀ ), 6,6-phenyl-C61-butyric acid methyl ester (PCBM) And 6,6-phenyl-C71-butyric acid methyl ester (PC ₇₀ BM: 6,6-phenyl-C71-butyric acid methyl ester) may be used singly or in combination of two or more.

The thickness of the electron transport layer 20 is preferably 1 nm to 10 nm based on the top of the p-type nanoparticle layer 30. [

The nanoparticle layer 30 is composed of a plurality of nanoparticles, and is formed by arranging a plurality of nanoparticles. The size of the nanoparticles may be from a few nanometers to a few micrometers.

Since the nanoparticle layer 30 is composed of a plurality of nanoparticles, the contact surface can be maximized and the efficiency of the solar cell can be increased.

The nanoparticles may comprise a p-type organic material. The p-type organic material may be a conductive polymer including a photosensitive structure and a functional group.

The solar cell of the present invention is characterized in that the photosensitive material is an organic structure nanoparticle rather than a dye or an inorganic material. Also, as shown in FIG. 2, the solar cell of the present invention is characterized in that an organic photovoltaic material that absorbs sunlight to generate an exciton 70 is used as a hole transport material.

The solar cell according to the present invention includes a nanoparticle layer 30 as an electron transport layer 20 and an organic hole transporting layer. The organic solar cell of the present invention includes an electron transport layer and an organic hole transport layer Each of which has a heterojunction interface and is in contact with the interface.

The photosensitive nanoparticles constituting the nanoparticle layer 30 are placed in contact with the electron transport layer 20 in an interface state, and the surface area is maximized through the nanoparticle arrangement of the polymer.

The solar cell of the present invention is a solar cell including an n-type semiconductor layer 20 and a p-type nanoparticle layer 30 forming a pn junction. The p-type nanoparticle layer 30 has a size of several nanometers to several nanometers It is composed of nanoparticles containing photoresponsive functional groups, which are micrometers.

The nanoparticles including the photosensitive structure and the functional group are p-type conductive polymers, and any conjugated polymers having the ability to absorb sunlight and conduct electricity can be used, and although not particularly limited, As the conjugated polymer having a discretized structure, it is preferable that the basic skeleton (repeating unit) of the conductive polymer is p-phenylenevinylene, fluorene, carbazole, thiophene, It is preferable to use poly (aryleneethynylene), triarylamine, phenothiazine, fluorenone, porphyrin and derivatives thereof, , And those in which the repeating unit of the conductive polymer is substituted with at least one substituent selected from the group consisting of alkyl, alkoxy, carboxyl, sulfone and alkyleneoxy, It is not.

The nanoparticle layer 30 may be composed of two or more layers, and the p-type nanoparticle layer 30 may be a patterned layer. The thickness of the nanoparticle layer 30 may be between 10 nm and 1 mu m.

An electron transport layer may be formed on the nanoparticle layer 30 to form a p-n junction, and the n-type material may be filled between the pores of the nanoparticle layer 30 by impregnation.

The hole transport layer 40 may include a polymer that ensures transparency and conductivity of visible light. In order to increase the contact with the first electrode 50, the poly (3-alkylthiophene) [P3AT: poly (3-alkylthiophene), poly (3,4-ethylenedioxythiophene) poly (3,4-ethylenedioxythiophene) poly (styrenesulfonate), and polyaniline (PANI) May be used singly or in combination of two or more.

The first electrode 50 may use a transparent electrode as a lower electrode. As the transparent electrode, a transparent electrode using indium tin oxide, fluorine-doped tin oxide, or carbon nanotubes and a material that ensures the same light transmission and conductivity can be used.

The substrate 60 may be composed of a glass substrate or a plastic substrate.

FIG. 3 is a plan view of a solar cell according to an embodiment of the present invention. First, a first electrode 50 is formed on a substrate 60 through a method such as coating. The first electrode 50 may be modified to have a hydrophilic surface. For example, cleaning using acetone and isopropyl alcohol and ultraviolet / ozone washing may be used.

Next, a thin film of the hole transporting layer 40 is formed on the first electrode 50. The hole transport layer 40 may be formed by spin coating a conductive polymer such as P3AT, PEDOT: PSS, and PANI. Further, after the spin coating, the substrate can be heat-treated at a temperature of 100 to 150 DEG C for 10 to 60 minutes in a vacuum state.

Next, the nanoparticle layer 30 is formed on the hole transport layer 40. The nanoparticle layer 30 may be formed by applying a solution containing a plurality of nanoparticles including a p-type organic material onto the hole transport layer 40. The solution containing the plurality of nanoparticles may comprise a mixture of water or a polar solvent.

The above-mentioned application uses a solution containing nanoparticles containing a photosensitive structure and a functional group, and it can be applied by screen printing, spin coating, drop casting, bar coating, May be performed by one or more methods selected from gravure coating, blade coating, spray coating, roll coating, inkjet printing, and the like.

In the step of forming the p-type nanoparticle layer 30, it is preferable to control the coating thickness of the solution so that the thickness of the nanoparticle layer 30 is 10 nm to 1 mu m.

The step of applying a solution containing a plurality of nanoparticles containing the p-type organic material to form a nanoparticle layer may be repeated one or more times to form a nanoparticle layer of two or more layers.

A heat treatment may be performed after applying a solution containing a plurality of nanoparticles including the p-type organic material. The heat treatment may be performed at a temperature of 100 to 150 DEG C for 10 to 60 minutes.

The concentration of the polymer in the solution containing the conductive polymer is 0.001 to 50% by weight, preferably 0.005 to 10% by weight, more preferably 0.005 to 10% by weight based on the total weight of the solution so that the contact surface of the p- 0.01 to 1% by weight, and most preferably 0.01 to 0.1% by weight.

The average size of the nanoparticles contained in the solution is 1 nm to 1 占 퐉, preferably 5 to 500 nm, more preferably 10 to 100 nm. It is preferable to control the particle size distribution of the nanoparticles contained in the solution so that the nanoparticles having various sizes are mixed.

The particle size distribution of the nanoparticles can be expressed by a polydispersity index (PDI), that is, a ratio (dw / dn) of the weight average particle size dw to the number average particle size dn. PDI is 1 or more, preferably 2 or more. The upper limit of the PDI may be 10, for example.

The main factor influencing the maximization of nanoparticle contact surface is particle size and distribution. Specifically, as the size of the nanoparticles and the distribution of the particles are wider, the porosity becomes smaller and the filling rate becomes larger. As a result, the efficiency of the solar cell increases as the contact surface becomes maximum.

Next, a solution containing an n-type material is impregnated on the nanoparticle layer 30 to form an electron transport layer 20.

The step of forming the electron transport layer 20 may include forming an n-type semiconductor material such as fullerene or PCBM to fill the pores existing in the p-type nanoparticle layer 30 and cover the upper portion of the nanoparticle layer 30 Impregnating the solution.

By impregnating the solution containing the n-type material, the pores of the p-type nanoparticle layer 30 are filled with the n-type semiconductor material, so that the nanoparticles and the n- .

The solution containing the n-type material may include a solvent. Examples of the solvent include chloroform, tetrahydrofuran, chlorobenzene, dichlorobenzene, toluene, dichloromethane, trichlorethylene, Or more.

The impregnation of the solution containing the n-type material can be performed by one or more methods selected from spin coating, drop casting, spray coating, and deep coating.

Next, a second electrode 10 is formed on the electron transport layer 20. The second electrode 10 may be formed by a method such as vapor deposition, sputtering, or screen printing.

The solar cell of the present invention manufactured by the above method has a high specific surface area as compared with the solar cell manufactured using the conventional bulk heterojunction method or the double layer structure.

Hereinafter, the present invention will be described in more detail by way of examples. The following examples are provided to illustrate the present invention and the scope of the present invention is not limited by the following examples.

[Example 1]

A glass substrate (ITO; 10 ohms / sq, 25 x 25 mm, manufactured by Sunik System) coated with indium tin oxide (first electrode) was used. The surface of the substrate was cleaned with acetone and isopropyl alcohol, It was modified to be hydrophilic by using an ozone washing machine.

In order to increase the contact with the metal electrode, PEDOT: PSS was spin coated at 4,000 rpm for 30 seconds and dried to form a hole transport layer, followed by heat treatment at 100 ° C for 30 minutes. Thereafter, a solution containing P3HT nanoparticles (particle size: 50 nm, particle size distribution (PDI): 1, concentration: 0.01 wt%) was coated on the hole transport layer by drop casting to form a single layer p- To form a nanoparticle layer.

A solution of PCBM (Aldrich), an electronically conductive n-type semiconductor layer material, formed on the formed p-type nanoparticle layer at a concentration of 15 mg / mL in chlorobenzene was coated by drop casting so that the internal void of the p- Filled with PCBM, and the top of the p-type nanoparticle layer was covered with PCBM. Thereafter, an Al electrode (second electrode) having a thickness of about 100 nm was formed on the n-type semiconductor layer by vacuum evaporation of Al using a thermal evaporator.

[Example 2]

A solar cell was prepared in the same manner as in Example 1, except that the process of forming the p-type nanoparticle layer in Example 1 was repeated three times to form three layers of p-type nanoparticles.

[Example 3]

Except that a p-type nanoparticle layer was formed using a solution containing P3HT nanoparticles having various particle sizes (particle size: 10 to 100 nm, particle size distribution: 2 or more, concentration: 0.01 wt% A solar cell was prepared in the same manner as in Example 2.

[Comparative Example 1]

Conventional multilayer structure solar cells in which film donors and acceptors are stacked in order

[Comparative Example 2]

Conventional bulk hetero-junction type solar cells formed by mixing a donor and an acceptor into a film form

[Test Example]

FIGS. 4 and 5 are scanning electron micrographs of a conductive nanoparticle-containing composition applied to form a p-type nanoparticle layer according to an embodiment of the present invention. As the particle size is controlled, nanoparticles having different sizes , Which are stacked and arranged in water layers.

6 is a UV-Vis spectrum of P3HT nanoparticles applied to form a p-type nanoparticle layer according to an embodiment of the present invention.

FIG. 7 is a graph showing a photoluminescence (PL) spectrum (solid line) of P3HT nanoparticles applied to form a p-type nanoparticle layer in accordance with an embodiment of the present invention, and an electron- (Dotted line) according to the optical quenching effect generated by filling pores in the p-type nanoparticle layer with PCBM, which is a semiconductor layer material, and shows the relationship between the p-type nanoparticles and the n- The quenching effect is generated by the action and the solar cell efficiency can be improved accordingly.

Table 1 compares the efficiency of the present invention and the conventional solar cell. The solar cell according to the present invention has a higher filling rate than that of the conventional solar cell and thus has excellent efficiency.

Comparative Example 1
(Multi-layer structure) Comparative Example 2
(Bulk hetero-junction) Example 1
(Introduction of nanoparticle layer) Short-circuit current (mA / cm2) 6.2 11.48 12.65 Open-circuit voltage (V) 0.32 0.51 0.6 Filling rate 0.4 0.4 0.55 efficiency(%) 0.8 2.34 5.61

10: Second electrode
20: electron transport layer
30: nanoparticle layer
40: hole transport layer
50: first electrode
60: substrate
70: exciton

Claims (18)

(a) a nanoparticle layer in which a plurality of nanoparticles including a p-type organic material are arranged to form a plurality of layers of two or more layers;
(b) a hole transport layer formed under the nanoparticle layer;
(c) a first electrode formed under the hole transport layer;
(d) an electron transport layer formed on the nanoparticle layer; And
(e) a second electrode formed on the electron transport layer,
Wherein the p-type organic material is a conductive polymer containing a photosensitive structure and a functional group and is at least one selected from the group consisting of p-phenylenevinylene, fluorene, carbazole, thiophene, poly (arylene ethenylene), triarylamine, Wherein the repeating unit is at least one repeating unit selected from the group consisting of alkyl, alkoxy, carboxyl, sulfone, and alkyleneoxy, and the repeating unit is a conductive polymer comprising at least one repeating unit selected from the group consisting of ≪ / RTI >
The size of the nanoparticles is 10 to 100 nm,
The polydispersity index (PDI) of the nanoparticles is 1 to 10,
Wherein the n-type material is filled with fullerene (C ₆₀ ), fullerene (C ₇₀ ), and n-type material. , 6,6-phenyl-C61-butyric acid methyl ester, and 6,6-phenyl-C71-butyric acid methyl ester,
Wherein the hole transport layer comprises at least one selected from poly (3-alkylthiophene), poly (3,4-ethylenedioxythiophene) poly (styrenesulfonate), and polyaniline,
A short circuit current is 12 mA / cm 2 or more, an open circuit voltage is 0.6 V or more, a filling rate is 0.5 or more, and an efficiency is 5% or more. delete delete delete delete delete delete delete delete delete A manufacturing method of a solar cell according to claim 1,
(a) forming a hole transporting layer on the first electrode;
(b) applying a solution containing a plurality of nanoparticles including a p-type organic material on the hole transport layer to form a nanoparticle layer of two or more layers;
(c) impregnating the nanoparticle layer with a solution containing an n-type material to form an electron transport layer; And
(d) forming a second electrode over the electron transport layer,
Wherein the content of the nanoparticles in the solution containing the plurality of nanoparticles is 0.01 to 50% by weight based on the total weight of the solution, and the solution containing the plurality of nanoparticles comprises a mixture of water or a polar solvent, Wherein the coating is carried out by at least one method selected from the group consisting of screen printing, spin coating, drop casting, bar coating, gravure coating, blade coating, spray coating, roll coating,
Wherein the solution comprising the n-type material comprises at least one solvent selected from chloroform, tetrahydrofuran, chlorobenzene, dichlorobenzene, toluene, dichloromethane, trichlorethylene, and xylene, wherein the n- Is carried out by one or more methods selected from spin coating, spray coating, and dip coating, and the impregnation of the solution containing the n-type material causes the n-type material to penetrate into the pores of the nanoparticle layer The pn junction is formed,
Wherein the spin-coating is performed in the step of forming the hole transporting layer, and then the heat treatment is performed at a temperature of 100 to 150 ° C. delete delete delete delete delete delete delete

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