KR101571528B1 - Perovskite solar cell improving photoelectric conversion efficiency and the manufacturing method thereof - Google Patents

Abstract

The present invention relates to a solar cell. The solar cell includes: a first electrode; a hole extraction layer formed on the upper part of the first electrode; a photoactive layer formed on the upper part of the hole extraction layer; an electron extraction layer formed on the upper part of the photoactive layer; and a second electrode formed on the upper part of the electron extraction layer. The photoactive layer includes: a perovskite layer which includes perovskite, has a thickness of 250-400 nm, and is represented by the chemical formula 1 described as AMX_3 or the chemical formula 2 described as A_2MX_4; and a fullerene derivative layer having a thickness of 41-60 nm. The electron extraction layer includes lithium fluoride (LiF) or cesium fluoride (CsF) having a thickness of 0.5-1 nm. According to the present invention, the solar cell uses the very thick perovskite layer which has the uniform thickness and a very compact structure as the photoactive layer and forms a very thin fullerene derivative layer on the top of the photoactive layer made of the perovskite layer, thereby exhibiting excellent photoelectric conversion efficiency. The present invention also includes the electron extraction layer made of LiF and CsF to exhibit more excellent photoelectric conversion efficiency. The method for manufacturing the solar cell enables an easy manufacturing process through a solution process.

Description

[0001] The present invention relates to a perovskite solar cell and a perovskite solar cell having improved photoelectric conversion efficiency,

The present invention relates to a perovskite solar cell and a perovskite solar cell having improved photoelectric conversion efficiency.

Research on renewable and clean alternative energy sources such as solar energy, wind power, and hydro power is actively being conducted to solve the global environmental problems caused by depletion of fossil energy and its use. Among these, there is a great interest in solar cells that change electric energy directly from sunlight. Here, a solar cell refers to a cell that generates a current-voltage by utilizing a photovoltaic effect that absorbs light energy from sunlight to generate electrons and holes.

Currently, np diode-type silicon (Si) single crystal based solar cells with a photoelectric conversion efficiency of more than 20% can be manufactured and used in actual solar power generation. Compound semiconductors such as gallium arsenide (GaAs) There is also solar cell using. However, since inorganic semiconductor-based solar cells require highly refined materials for high efficiency, a large amount of energy is consumed in the purification of raw materials, and expensive processes are required in the process of making single crystals or thin films using raw materials And the manufacturing cost of the solar cell can not be lowered, which has been a hindrance to a large-scale utilization.

Accordingly, in order to manufacture a solar cell at a low cost, it is necessary to drastically reduce the cost of the material or manufacturing process used as a core of the solar cell. As an alternative to the inorganic semiconductor-based solar cell, Type solar cells and organic solar cells have been actively studied.

However, in the case of an organic solar cell using a conductive polymer, the photoelectric conversion efficiency stays at 8% (Advanced Materials, 23 (2011) 4636). In the case of a dye-sensitized solar cell, the photoelectric conversion efficiency (Science 334, (2011) 629), and in the case of using a solid type hole conductor, it is still low to 7 to 8%. Organic-inorganic hybrid solar cells, which combine inorganic semiconductor nanoparticles and hole-conducting polymers with dye-sensitized solar cell structures, are still showing efficiencies of about 6% (NanoLetters, 11 (2011) 4789). Accordingly, there is an urgent need to develop a solar cell capable of having a sufficiently high efficiency to replace a conventional silicon single crystal based solar cell.

Accordingly, the present inventors have studied solar cells including perovskite. In a solar cell in which a first electrode, a hole extraction layer, a photoactive layer, an electron extraction layer, and a second electrode are sequentially stacked, (LiF) or cesium fluoride (CsF) in a thickness of 0.5 to 1 nm, wherein the electron extraction layer comprises a perovskite layer having a thickness of 250 to 400 nm and a fullerene derivative layer having a thickness of 41 to 60 nm And found that the photovoltaic conversion efficiency of the solar cell was excellent, and completed the present invention.

It is an object of the present invention to provide a perovskite solar cell and a perovskite solar cell having improved photoelectric conversion efficiency.

In order to achieve the above object,

A first electrode;

A hole extraction layer formed on the first electrode;

A photoactive layer formed on the hole extracting layer;

An electron extraction layer formed on the photoactive layer; And

And a second electrode formed on the electron extraction layer,

Wherein the photoactive layer comprises a perovskite layer having a thickness of 250 to 400 nm and a fullerene derivative layer having a thickness of 41 to 60 nm, the perovskite being represented by the following formula (1) or (2)

The electron extraction layer provides a solar cell comprising 0.5 to 1 nm thick lithium fluoride (LiF) or cesium fluoride (CsF).

≪ Formula 1 >

AMX ₃

(In the formula 1,

A is a straight or branched chain alkyl or an alkali metal ion of the C _{1 -20} C _{1 -20} straight or branched chain alkyl, an amine group is substituted for,

M is ^{Cu 2 +, Ni 2 +,} Co 2 +, Fe 2 +, Mn 2 +, Cr 2 +, Pd 2 +, Cd 2 +, Ge 2 +, Sn 2 +, Pb 2 + or Yb ^{2 +} a ,

X is a halogen ion.)

(2)

A ₂ MX ₄

(In the formula (2)

A is a straight or branched chain alkyl or an alkali metal ion of the C _{1 -20} C _{1 -20} straight or branched chain alkyl, an amine group is substituted for,

M is ^{Cu 2 +, Ni 2 +,} Co 2 +, Fe 2 +, Mn 2 +, Cr 2 +, Pd 2 +, Cd 2 +, Ge 2 +, Sn 2 +, Pb 2 + or Yb ^{2 +} a ,

And X is a halogen ion).

In addition,

Forming a hole extraction layer on the first electrode (step 1);

A hole-injection layer formed in step 1, a perovskite layer having a thickness of 250 to 400 nm and a perovskite layer having a thickness of 41 to 60 nm, Forming an active layer (step 2);

(Step 3) of forming an electron extraction layer made of lithium fluoride (LiF) or cesium fluoride (CsF) in a thickness of 0.5 to 1 nm on the photoactive layer formed in step 2; And

And forming a second electrode on the electron extraction layer formed in step 3 (step 4).

Further,

A first electrode;

A hole extraction layer formed on the first electrode;

A photoactive layer formed on the hole extracting layer;

An electron extraction layer formed on the photoactive layer; And

And a second electrode formed on the electron extraction layer, the method comprising the steps of:

(A) preparing a perovskite precursor solution comprising an organic halide, a metal halide and a polar aprotic solvent;

(B) forming a perovskite layer having a thickness of 250 to 400 nm by applying the perovskite precursor solution prepared in step (a) on the hole extract layer; And

Forming a fullerene derivative layer having a thickness of 41 to 60 nm (step c) by applying a solution containing a fullerene derivative on the perovskite layer formed in the step b) to form a ferroelectric layer having a thickness of 250 to 400 nm A skylight layer and a 41 to 60 nm thick fullerene derivative layer,

Wherein the electron extraction layer is formed of lithium fluoride (LiF) or cesium fluoride (CsF) in a thickness of 0.5 to 1 nm.

Further,

A solar cell module including the solar cell is provided.

The solar cell according to the present invention uses a perovskite layer having a dense structure, a very thick and uniform thickness as a photoactive layer, and a very thin fullerene derivative layer is formed on the photoactive layer made of the perovskite layer Thereby exhibiting excellent photoelectric conversion efficiency. Further, the photoelectric conversion efficiency can be further improved by including an electron extraction layer made of lithium fluoride (LiF) or cesium fluoride (CsF). Furthermore, the manufacturing method of the solar cell according to the present invention has an advantage that it can be easily manufactured through a solution process.

1 is a schematic view showing an example of a solar cell according to the present invention;
FIG. 2 is a photograph of a section of a solar cell manufactured in Example 1 according to the present invention observed by a scanning electron microscope (SEM); FIG.
FIG. 3 is a photograph of the surface of the perovskite layer observed by a scanning electron microscope (SEM) after the formation of the perovskite layer in the step 2 of Example 1 according to the present invention;
4 is a photograph of the surface of the perovskite layer after formation of the perovskite layer in the step 2 of Example 1 according to the present invention with an atomic force microscope (AFM);
FIG. 5 is a photograph of a surface of a fullerene derivative layer observed by a scanning electron microscope (SEM) after forming the fullerene derivative layer in step 2 of Example 1 according to the present invention. FIG.

The present invention

A first electrode;

A hole extraction layer formed on the first electrode;

A photoactive layer formed on the hole extracting layer;

An electron extraction layer formed on the photoactive layer; And

And a second electrode formed on the electron extraction layer,

Wherein the photoactive layer comprises a perovskite layer having a thickness of 250 to 400 nm and a fullerene derivative layer having a thickness of 41 to 60 nm, the perovskite being represented by the following formula (1) or (2)

The electron extraction layer provides a solar cell comprising 0.5 to 1 nm thick lithium fluoride (LiF) or cesium fluoride (CsF).

≪ Formula 1 >

AMX ₃

(In the formula 1,

A is a straight or branched chain alkyl or an alkali metal ion of the C _{1 -20} C _{1 -20} straight or branched chain alkyl, an amine group is substituted for,

M is ^{Cu 2 +, Ni 2 +,} Co 2 +, Fe 2 +, Mn 2 +, Cr 2 +, Pd 2 +, Cd 2 +, Ge 2 +, Sn 2 +, Pb 2 + or Yb ^{2 +} a ,

X is a halogen ion.)

(2)

A ₂ MX ₄

(In the formula (2)

A is a straight or branched chain alkyl or an alkali metal ion of the C _{1 -20} C _{1 -20} straight or branched chain alkyl, an amine group is substituted for,

M is ^{Cu 2 +, Ni 2 +,} Co 2 +, Fe 2 +, Mn 2 +, Cr 2 +, Pd 2 +, Cd 2 +, Ge 2 +, Sn 2 +, Pb 2 + or Yb ^{2 +} a ,

And X is a halogen ion).

Here, the structure of the solar cell according to the present invention is schematically shown in FIG. 1 as an example,

Hereinafter, a solar cell according to the present invention will be described in detail with reference to a schematic view of FIG.

A solar cell comprising a conventional perovskite layer and a double layer of a fullerene derivative layer as a photoactive layer has a thickness of about 50 nm due to the morphology problem associated with the roughness of the thicker perovskite layer If the fullerene derivative layer is formed, there is a problem that the second electrode and the perovskite layer are in direct contact with each other and current leakage occurs. To solve this problem, the fullerene derivative layer has a thick thickness (about 110 nm or more) Or a method of laminating a metal oxide (for example, TiO ₂ ) layer to another n-type layer or the like is used. In addition, there is a problem in forming a dense, flat and thick perovskite layer through a solution process, and a solar cell device is implemented through a vacuum deposition process.

However, the solar cell according to the present invention uses a perovskite layer having a dense structure and a very thick and uniform thickness as a photoactive layer, and by using a very thin fullerene derivative layer on the perovskite layer, Photoelectric conversion efficiency can be exhibited.

Further, by including lithium fluoride (LiF) or cesium fluoride (CsF) as an electron extracting layer of the solar cell, it is possible to exhibit more excellent photoelectric conversion efficiency.

In the solar cell 100 according to the present invention, the first electrode 10 may be a conductive electrode that is ohmic-bonded to the hole extracting layer 20, and may be a transparent conductive electrode to improve light transmission. For example, the first electrode may include at least one of aluminum-doped zinc oxide (AZO), indium-tin oxide (ITO), zinc oxide (ZnO) ATO; Aluminium-tin oxide; SnO 2: Al), the fluorine-containing tin oxide (FTO: fluorine-doped tin oxide ), graphene (graphene), carbon nanotubes and PEDOT: PSS or the like, but is not limited thereto.

In addition, the first electrode 10 may further include a substrate (not shown) positioned under the first electrode. The substrate can serve as a support for supporting the first electrode, and can be used without limitation as long as it is a transparent substrate through which light is transmitted. The substrate can be any substrate that can be placed on the front electrode in a conventional solar cell It can be used without. For example, the substrate may be a rigid substrate comprising a glass substrate or a rigid substrate comprising polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), polycarbonate (PC) (TAC), polyethersulfone (PES), and the like.

In the solar cell 100 according to the present invention, the hole extracting layer 20 is formed on the first electrode 10.

The hole extraction layer 20 may include a conductive polymer. The conductive polymer may be, for example, poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS).

In the solar cell 100 according to the present invention, the photoactive layer 30 is formed on the hole extraction layer 20.

The photoactive layer 30 may include a perovskite layer 31 having a thickness of 250 to 400 nm and a fullerene derivative layer 32 having a thickness of 41 to 60 nm including perovskite represented by Formula 1 or Formula 2, Is preferably a bilayer.

If the thickness of the perovskite layer 31 is less than 250 nm, there is a problem that the absorption of light is insufficient and the current density is low and the efficiency is reduced. When the thickness exceeds 400 nm, the distance to the pn interface The generated excitons migrate to the pn interface and can not be effectively separated, thereby decreasing the efficiency.

When the thickness of the fullerene derivative layer 32 is less than 41 nm, there is a problem that the photoelectric conversion efficiency of the solar cell 100 sharply decreases. When the thickness of the fullerene derivative layer 32 exceeds 60 nm, the photoelectric conversion efficiency There is a problem in which the amount of water is reduced sharply.

Further, the perovskite is preferably a perovskite represented by the formula (1) or (2), wherein M is located at the center of a unit cell in the perovskite structure, X is a unit cell And an octahedron structure is formed around the center of M, and A may be located at each corner of the unit cell.

As a specific example, the perovskite is AMX ^a _x X ^b _y Or A ₂ MX ^a _x X ^b _y (real number 0 <x <3, real number 0 <y <3, x + y = 3, and X ^a and X ^b are different halogen ions).

In addition, in Formula 1 and Formula 2 A may be an amine to straight or branched chain alkyl, of C _{1 -7} include an amine group preferably comprises methyl (methyl ammonium ion, CH ₃ NH ₃ ^+).

As a more specific example, the perovskite may be CH ₃ NH ₃ PbI _x Cl _y (real number 0 <x <3, real number 0 <y <3 and x + y = 3), CH ₃ NH ₃ PbI _x Br _y (0 <x <3, 0 <y <3 and x + y = 3), CH ₃ NH ₃ PbCl _x Br _y + y = 3), and _{CH 3 NH 3 PbI x F y} (0 <x <3 mistakes, 0 <y <3 is real and x + y = 3 and) can be selected at least one or both on, and (CH ₃ NH ₂ ) ₂ PbI _x Cl _y (real number with 0 <x <4, real number with 0 <y <4 and x + y = 4), CH ₃ NH ₃ PbI _x Br _y X + y = 4), CH ₃ NH ₃ PbCl _x Br _y (real number with 0 <x <4, real number with 0 <y <4 and x + y = 4) and CH ₃ NH ₃ PbI _x F _y (a real number with 0 <x <4, a real number with 0 <y <4, and x + y = 4).

In addition, the fullerene derivative PCBM ([6,6] -phenyl-C 61 -butyric acid methyl ester), PC 71 BM, Bis-PCBM, IC 60 MA (indene-C 60 monoadduct), IC 70 MA, IC 60 _{BA (indene-C 60 bisadduct)} , IC 70 BA, BC 60 MA (biindene-C 60 monoadduct), and BC ₇₀ MA, and the like, and preferably may be a PCBM, but is not limited thereto.

In the solar cell 100 according to the present invention, the electron extraction layer 40 is formed on the photoactive layer 30.

Preferably, the electron extraction layer 40 is lithium fluoride (LiF) or cesium fluoride (CsF) 0.5 to 1 nm thick.

In general, organic light emitting devices (OLEDs) and the like use an electrode including lithium fluoride and a metal as a cathode. However, in the case of organic solar cells (OPVs), the performance of the device depends on the presence or absence of lithium fluoride These results are not significantly different.

However, the solar cell 100 according to the present invention can improve the photoelectric conversion efficiency of the solar cell by including the electron extraction layer 40 made of lithium fluoride or cesium fluoride.

In the solar cell 100 according to the present invention, the second electrode 50 is formed on the electron extraction layer 40.

The second electrode 50 may be formed of a metal such as Al, Ca, Ag, Au, Pt, Cu, Zn, Metal.

As a specific example, the second electrode 50 may be an aluminum electrode, and the thickness of the electrode may be 50 to 200 nm.

In addition,

Forming a hole extraction layer on the first electrode (step 1);

The hole extraction layer formed in the step 1 is formed with a perovskite layer having a thickness of 250 to 400 nm and a perovskite layer having a thickness of 41 to 60 nm, Forming an active layer (step 2);

(Step 3) of forming an electron extraction layer made of lithium fluoride (LiF) or cesium fluoride (CsF) in a thickness of 0.5 to 1 nm on the photoactive layer formed in step 2; And

And forming a second electrode on the electron extraction layer formed in step 3 (step 4).

Hereinafter, a method for manufacturing a solar cell according to the present invention will be described in detail for each step.

First, in the method of manufacturing a solar cell according to the present invention, step 1 is a step of forming a hole extraction layer on the first electrode.

Specifically, the first electrode of step 1 may be a conductive electrode that is ohmic-bonded to the hole extraction layer, and a transparent conductive electrode may be used to improve light transmission. The first electrode of step 1 may be, for example, aluminum-doped zinc oxide (AZO), indium-tin oxide (ITO), zinc oxide (ZnO) aluminum tin (ATO; Aluminium-tin oxide; SnO 2: Al), the fluorine-containing tin oxide (FTO: fluorine-doped tin oxide ), graphene (graphene), carbon nanotubes and PEDOT: PSS, but the like, are not limited to Do not.

The first electrode of step 1 may further include a substrate located under the first electrode. The substrate can serve as a support for supporting the first electrode, and can be used without limitation as long as it is a transparent substrate through which light is transmitted. The substrate can be any substrate that can be placed on the front electrode in a conventional solar cell It can be used without. For example, the substrate may be a rigid substrate comprising a glass substrate or a rigid substrate comprising polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), polycarbonate (PC) (TAC), polyethersulfone (PES), and the like.

At this time, the first electrode of the step 1 may be deposited on the substrate by sputtering, metal-organic chemical vapor deposition (MOCVD), or the like.

In addition, the hole extracting layer in the step 1 may include a conductive polymer. As the conductive polymer, for example, poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS) may be used.

Further, as a method of forming the hole extracting layer of the step 1 above the first electrode, a method such as spin coating may be used, but the present invention is not limited thereto.

Next, in the method for manufacturing a solar cell according to the present invention, step 2 is a step of forming a layer having a thickness of 250 to 400 nm including perovskite represented by the above formula (1) or (2) A perovskite layer and a 41 to 60 nm thick fullerene derivative layer.

A solar cell comprising a conventional perovskite layer and a double layer of a fullerene derivative layer as a photoactive layer has a thickness of about 50 nm due to the morphology problem associated with the roughness of the thicker perovskite layer If the fullerene derivative layer is formed, there is a problem that the second electrode and the perovskite layer are in direct contact with each other and current leakage occurs. To solve this problem, the fullerene derivative layer has a thick thickness (about 110 nm or more) Or a method of laminating a metal oxide (for example, TiO ₂ ) layer to another n-type layer or the like is used.

However, in the present invention, a perovskite layer having a dense structure and having a very thick and uniform thickness is formed, and a very thin fullerene derivative layer is formed on the perovskite layer to exhibit excellent photoelectric conversion efficiency .

In addition, when a metal oxide (e.g., TiO ₂ ) layer is formed, a sintering process at a high temperature (about 400 ° C) is necessarily required. However, the manufacturing method of a solar cell according to the present invention is, There is an advantage that a photoactive layer can be formed by a simple method such as heat treatment at a low temperature (about 50 to 120 ° C) after forming the active layer.

Furthermore, the method of manufacturing a solar cell according to the present invention has an advantage that a photoactive layer can be easily formed through a solution process such as spin coating or printing.

Specifically, in the step 2, the photoactive layer is, for example,

Preparing a perovskite precursor solution comprising an organic halide and a metal halide (step a);

(B) forming a perovskite layer having a thickness of 250 to 400 nm by applying the perovskite precursor solution prepared in step (a) on the hole extract layer; And

Forming a fullerene derivative layer having a thickness of 41 to 60 nm (step c) by applying a solution containing a fullerene derivative on the perovskite layer formed in the step b).

First, step a is a step of preparing a perovskite precursor solution containing an organic halide and a metal halide.

Specifically, the perovskite precursor solution in step (a) may be prepared by dissolving the perovskite precursor solution of step (a) in a solvent or by dissolving the perovskite precursor solution in step (a) (AX), which is a compound of A and X, and a metal halide (MX ₂ ) which is a compound of M and X according to the definition of the above formula ( ₂ ).

For example, the organic halide of step (a) may be a compound represented by the following formula (3).

(3)

AX

(3)

A is a straight or branched chain alkyl or an alkali metal ion of the C _{1 -20} C _{1 -20} straight or branched chain alkyl, an amine group is substituted for,

And X is a halogen ion).

In addition, the metal halide of step (a) may be a compound represented by the following formula (4).

&Lt; Formula 4 >

MX ₂

(In the formula 4,

M is ^{Cu 2 +, Ni 2 +,} Co 2 +, Fe 2 +, Mn 2 +, Cr 2 +, Pd 2 +, Cd 2 +, Ge 2 +, Sn 2 +, Pb 2 + or Yb ^{2 +} a ,

And X is a halogen ion).

The perovskite precursor solution in step a may further include a solvent. The solvent may be any solvent that dissolves an organic halide or a metal halide and can be easily volatilized and removed during drying. For example, the solvent may be a non-aqueous polar organic solvent and may be a solvent such as gamma-butyrolactone, formamide, N, N-dimethylformamide, diformamide, acetonitrile, tetrahydrofuran, dimethylsulfoxide , Diethylene glycol, 1-methyl-2-pyrrolidone, N, N-dimethylacetamide, acetone,? -Terpineol,? -Terpineol, dihydrotopeenol, 2-methoxyethanol, Acetyl acetone, methanol, ethanol, propanol, butanol, pentanol, hexanol, ketone, methyl isobutyl ketone and the like.

In this case, the perovskite precursor solution in step a preferably includes a polar aprotic solvent. The polar aprotic solvent may form a solvate with an organic ion, a metal ion, a halogen ion and a complex ion thereof derived from an organic halide and a metal halide.

When a solvent compound is formed as described above, an extremely dense perovskite thin film can be formed.

The molar ratio of the metal halide and the organic halide contained in the perovskite precursor solution in step a is preferably 1: 1 to 2. If the molar ratio of the metal halide and the organic halide contained in the perovskite precursor solution is out of the above range, it is difficult to form the perovskite represented by the above formula (1) or (2) have.

Next, in step b, the perovskite precursor solution prepared in step a is coated on the hole extraction layer to form a perovskite layer having a thickness of 250 to 400 nm.

Specifically, when the perovskite precursor solution prepared in the step (a) is applied on the hole extracting layer, the solvent of the perovskite precursor solution is volatilized and removed, and the perovskite represented by the formula (1) or A crystal phase can be spontaneously formed.

The perovskite in the step b is preferably a perovskite represented by the above formula (1) or (2), wherein M is located in the center of a unit cell in the perovskite structure, X is a unit An octahedron structure is formed at the center of each side of the cell, centered at M, and A may be located at each corner of the unit cell.

As a specific example, the perovskite is AMX ^a _x X ^b _y Or A ₂ MX ^a _x X ^b _y (real number 0 <x <3, real number 0 <y <3, x + y = 3, and X ^a and X ^b are different halogen ions).

In addition, in Formula 1 and Formula 2 A may be an amine to straight or branched chain alkyl, of C _{1 -7} include an amine group preferably comprises methyl (methyl ammonium ion, CH ₃ NH ₃ ^+).

As a more specific example, the perovskite may be CH ₃ NH ₃ PbI _x Cl _y (real number 0 <x <3, real number 0 <y <3 and x + y = 3), CH ₃ NH ₃ PbI _x Br _y (0 <x <3, 0 <y <3 and x + y = 3), CH ₃ NH ₃ PbCl _x Br _y + y = 3), and _{CH 3 NH 3 PbI x F y} (0 <x <3 mistakes, 0 <y <3 is real and x + y = 3 and) can be selected at least one or both on, and (CH ₃ NH ₂ ) ₂ PbI _x Cl _y (real number with 0 <x <4, real number with 0 <y <4 and x + y = 4), CH ₃ NH ₃ PbI _x Br _y X + y = 4), CH ₃ NH ₃ PbCl _x Br _y (real number with 0 <x <4, real number with 0 <y <4 and x + y = 4) and CH ₃ NH ₃ PbI _x F _y (a real number with 0 <x <4, a real number with 0 <y <4, and x + y = 4).

In the step b, the perovskite precursor solution may be applied by a spin coating method, but the present invention is not limited thereto. For example, in the case of coating using the spin coating method in the step b, spin coating is carried out at a rotation speed of 500 to 2,000 rpm for 10 to 30 seconds, followed by spin coating at a rotation speed of 2,000 to 6,000 rpm of 30 to 120 Lt; / RTI &gt; seconds.

In addition, the perovskite precursor solution may be applied in step b, and then the perovskite layer may be formed by heat treatment at a temperature of 50 to 150 ° C, but the heat treatment temperature is not limited thereto.

Further, when the thickness of the perovskite layer formed in the step b is less than 250 nm, there is a problem that the absorption of light is insufficient and the photocurrent density is low and the efficiency is decreased. When the thickness exceeds 400 nm, The generated excitons migrate to the pn interface and can not be effectively separated, thereby decreasing the efficiency.

Next, the step c is a step of forming a fullerene derivative layer having a thickness of 41 to 60 nm by applying a solution containing a fullerene derivative on the perovskite layer formed in the step b.

A solar cell comprising a conventional perovskite layer and a double layer of a fullerene derivative layer as a photoactive layer has a thickness of about 50 nm due to the morphology problem associated with the roughness of the thicker perovskite layer However, in the step c of the present invention, the ferroelectric layer has a dense structure formed in the step b, and the ferroelectric layer has a very fine structure. A very thin fullerene derivative layer can be formed by forming a fullerene derivative layer on the perovskite layer having a thick and uniform thickness.

Specifically, in the step c, a fullerene derivative layer having a thickness of 41 to 60 nm is formed. When the thickness of the fullerene derivative layer is less than 41 nm, the photoelectric conversion efficiency of the solar cell is drastically reduced. There is a problem that the photoelectric conversion efficiency of the solar cell drastically decreases.

In order to form the fullerene derivative layer having such a thin thickness, for example, the concentration and application method of the solution containing the fullerene derivative of the step c may be controlled. At this time, the concentration of the solution containing the fullerene derivative of the step c may be 6 to 10 mg / ml, and when the solution containing the fullerene derivative is applied by spin coating, the solution containing the fullerene derivative may be added at a rotation speed of 800 to 1,600 rpm For 30 to 120 seconds.

In addition, the fullerene derivative of the phase c is PCBM ([6,6] -phenyl-C 61 -butyric acid methyl ester), PC 71 BM, Bis-PCBM, IC 60 MA (indene-C 60 monoadduct), IC 70 MA , IC ₆₀ BA (indene-C ₆₀ bisadduct), IC ₇₀ BA, BC ₆₀ MA (biindene-C ₆₀ monoadduct), BC ₇₀ MA and the like can be used. .

Next, in the method for manufacturing a solar cell according to the present invention, Step 3 is a step of forming an electron (hole) layer made of lithium fluoride (LiF) or cesium fluoride (CsF) Thereby forming an extraction layer.

In general, organic light emitting devices (OLEDs) use an electrode containing lithium fluoride or cesium fluoride and a metal as a cathode. In the case of organic solar cells (OPVs), lithium fluoride or cesium fluoride The results show that the performance of the device is not significantly different depending on the presence or absence of the device.

However, the solar cell according to the present invention can improve the photoelectric conversion efficiency of a solar cell by including an electron extraction layer made of lithium fluoride or cesium fluoride.

Next, in the method of manufacturing a solar cell according to the present invention, Step 4 is a step of forming a second electrode on the electron extraction layer formed in Step 3 above.

The second electrode includes a metal such as aluminum (Al), calcium (Ca), silver (Ag), zinc (Zn), gold (Au), platinum (Pt), copper (Cu) .

As a specific example, the second electrode may be made of aluminum, and the thickness of the aluminum electrode may be 50 to 200 nm.

Further,

A first electrode;

A hole extraction layer formed on the first electrode;

A photoactive layer formed on the hole extracting layer;

An electron extraction layer formed on the photoactive layer; And

And a second electrode formed on the electron extraction layer, the method comprising the steps of:

(A) preparing a perovskite precursor solution comprising an organic halide, a metal halide and a polar aprotic solvent;

(B) forming a perovskite layer having a thickness of 250 to 400 nm by applying the perovskite precursor solution prepared in step (a) on the hole extract layer; And

Forming a fullerene derivative layer having a thickness of 41 to 60 nm (step c) by applying a solution containing a fullerene derivative on the perovskite layer formed in the step b) to form a ferroelectric layer having a thickness of 250 to 400 nm A skylight layer and a 41 to 60 nm thick fullerene derivative layer,

Wherein the electron extraction layer is formed of lithium fluoride (LiF) or cesium fluoride (CsF) in a thickness of 0.5 to 1 nm.

A solar cell comprising a conventional perovskite layer and a double layer of a fullerene derivative layer as a photoactive layer has a thickness of about 50 nm due to the morphology problem associated with the roughness of the thicker perovskite layer If the fullerene derivative layer is formed, there is a problem that the second electrode and the perovskite layer are in direct contact with each other and current leakage occurs. To solve this problem, the fullerene derivative layer has a thick thickness (about 110 nm or more) Or a method of laminating a metal oxide (for example, TiO ₂ ) layer to another n-type layer or the like is used. In addition, there is a problem in forming a dense, flat and thick perovskite layer through a solution process, and a solar cell device is implemented through a vacuum deposition process.

However, the method for improving the efficiency of the solar cell according to the present invention uses a perovskite layer having a dense structure and a uniform thickness of 250 to 400 nm as a photoactive layer, and a very thin 41 The photoelectric conversion efficiency of the solar cell can be improved by a method using a fullerene derivative layer having a thickness of 60 nm to 60 nm.

Further, by including lithium fluoride (LiF) or cesium fluoride (CsF) in a thickness of 0.5 to 1 nm as the electron extracting layer of the solar cell, the photoelectric conversion efficiency can be further improved.

Further,

A solar cell module including the solar cell is provided.

The present invention provides a solar cell module in which the above-described solar cell or a solar cell manufactured by the above-described manufacturing method is arranged as a unit cell and two or more cells are arranged and electrically connected to each other. The solar cell module may have an arrangement and structure of cells commonly used in the field of solar cells, and may further include a usual light collecting means for collecting solar light, and a usual optical block for guiding sunlight path.

Hereinafter, the present invention will be described in detail with reference to the following examples and experimental examples.

It should be noted, however, that the following examples and experimental examples are illustrative of the present invention, but the scope of the invention is not limited by the examples and the experimental examples.

PREPARATION EXAMPLE 1 Preparation of perovskite precursor solution

Methyl ammonium iodide (CH ₃ NH ₃ I) and red diimide iodide (PbI ₂₎ a 1: 1 molar ratio to the dimethyl lactone sulfoxide (DMSO) and gamma -butyrolactone (г-butyrolacton, GBL) of 3: 7 volume ratio , And the mixture was stirred at a temperature of 60 ° C for 12 hours to prepare a perovskite precursor solution.

&Lt; Example 1 > Production of solar cell 1

Step 1: A glass substrate coated with indium-tin oxide (ITO) was washed with acetone, a cleaning solution, distilled water and isopropyl alcohol, and then treated with UV-ozone for 15 minutes to prepare a first electrode.

Poly (3,4-ethylenedioxythiophene) (poly (styrenesulfonic acid), levios, A14083) was spin-coated on the prepared first electrode at a rotation speed of 3,000 rpm for 60 seconds, And dried for 20 minutes to form a hole extraction layer.

Step 2: The perovskite precursor solution prepared in Preparation Example 1 was coated on the hole extraction layer formed in Step 1, spin-coated at a rotation speed of 1,000 rpm for 20 seconds, and then continuously rotated at 4,000 rpm For 60 seconds, and dried at a temperature of 100 DEG C to form a perovskite layer having a thickness of about 290 nm.

A PCBM solution having a concentration of 12 mg / ml was spin-coated on the perovskite layer formed above at a rotation speed of 1,200 rpm for 60 seconds to form a fullerene derivative layer having a thickness of about 55 nm.

Step 3: About 0.5 nm thick lithium fluoride (LiF) was formed on the fullerene derivative layer formed in step 2 above.

Step 4: An aluminum (Al) electrode having a thickness of about 100 nm was formed on the electron extraction layer formed in the step 3 to manufacture a solar cell.

&Lt; Example 2 > Production of solar cell 2

A solar cell was fabricated in the same manner as in Example 1 except that a fullerene derivative layer having a thickness of about 47 nm was formed using a PCBM solution having a concentration of 10 mg / ml in the step 2 of Example 1.

&Lt; Comparative Example 1 &

A solar cell was prepared in the same manner as in Example 1 except that a fullerene derivative layer having a thickness of about 40 nm was formed using a PCBM solution having a concentration of 8 mg / ml in the step 2 of Example 1 above.

&Lt; Comparative Example 2 &

A solar cell was prepared in the same manner as in Example 1, except that a fullerene derivative layer having a thickness of about 100 nm was formed using a PCBM solution having a concentration of 15 mg / ml in the step 2 of Example 1 above.

&Lt; Comparative Example 3 &

A solar cell was manufactured in the same manner as in Example 1, except that a fullerene derivative layer having a thickness of about 120 nm was formed using a PCBM solution having a concentration of 20 mg / ml in the step 2 of Example 1 above.

&Lt; Comparative Example 4 &

A solar cell was prepared in the same manner as in Example 1, except that a fullerene derivative layer having a thickness of about 140 nm was formed using a PCBM solution having a concentration of 25 mg / ml in the step 2 of Example 1 above.

&Lt; Comparative Example 5 &

A solar cell was manufactured in the same manner as in Example 1, except that a 220 nm thick fullerene derivative layer was formed using a PCBM solution having a concentration of 30 mg / ml in the step 2 of Example 1.

&Lt; Comparative Example 6 >

A solar cell was manufactured in the same manner as in Example 1 except that the step 3 of Example 1 was not performed to form an electron extraction layer of lithium fluoride (LiF).

<Experimental Example 1> Scanning electron microscope (SEM) and atomic force microscope (AFM) observation

In order to confirm the shape of the photoactive layer in the solar cell according to the present invention, the cross section of the solar cell manufactured in Example 1 was observed with a scanning electron microscope (SEM), and in the step 2 of Example 1, The surface of the perovskite layer was observed with a scanning electron microscope (SEM) and an atomic force microscope (AFM). After forming the fullerene derivative layer in the step 2 of Example 1, the surface of the fullerene derivative layer Was observed with a scanning electron microscope (SEM), and the results are shown in Figs. 2 to 5. Fig.

As shown in FIG. 2, the cross section of Example 1, which is a solar cell according to the present invention, is composed of indium tin oxide as a first electrode, and PEDOT: PSS having a thickness of about 40 nm as a hole extracting layer on the indium tin oxide Is located. Also, it can be seen that a perovskite layer having a dense structure and a uniform thickness of about 290 nm is located on the PEDOT: PSS, and a PCBM layer having a thickness of about 55 nm is formed on the perovskite layer . Furthermore, it was confirmed that a buffer layer composed of an aluminum electrode of about 100 nm thickness and lithium fluoride of about 0.5 nm thickness was formed on the PCBM layer.

Further, as shown in FIG. 3, the surface of the perovskite layer in the solar cell according to the present invention is characterized in that the surface of the perovskite layer is composed of well-developed grains having a size of several hundred nanometers And it was confirmed that a homogenous flat surface was formed so that the entire surface could be covered with the fullerene derivative layer.

Further, as shown in FIG. 4, the surface of the perovskite layer in the solar cell according to the present invention was analyzed by an atomic force microscope, and it was confirmed that the surface showed a roughness of about 10 nm (rms roughness).

Therefore, it can be seen that a thin fullerene derivative layer can be formed on the perovskite layer because the perovskite layer of the solar cell according to the present invention can have a very low roughness.

As shown in FIG. 5, the surface of the fullerene derivative layer in the solar cell according to the present invention is very smooth, and the surface of the perovskite is 55 nm in thickness The PCBM was completely covered by the PCBM.

<Experimental Example 2> Analysis of Photoelectric Conversion Efficiency of Solar Cell

In order to confirm the photoelectric conversion efficiency of the solar cell according to the present invention, the solar cells prepared in Examples 1 and 2 and Comparative Examples 1 to 6 were measured with a solar simulator (Spectra phsics Co.) The measurement conditions are AM 1.5 (1 sun, 100 mW / cm ² , 25 캜). The short circuit current density (J _SC ), the open circuit voltage (V _OC ), the curve factor (FF) and the photoelectric conversion efficiency (η) of the solar cell were measured and the results are shown in Table 1 below.

Open circuit voltage (V) Short circuit current density (mA / cm ² ) Curve factor
(%) Photoelectric conversion efficiency
(%) Example 1 0.89 21.12 71.47 13.42 Example 2 0.88 19.72 69.96 12.22 Comparative Example 1 0.29 17.98 40.16 1.70 Comparative Example 2 0.86 19.79 69.98 11.93 Comparative Example 3 0.85 19.07 67.51 10.97 Comparative Example 4 0.85 16.93 61.69 8.85 Comparative Example 5 0.84 16.32 63.78 8.72 Comparative Example 6 0.85 19.20 70.80 11.50

As shown in Table 1, in Examples 1 and 2, which are solar cells having a fullerene derivative layer with a thin thickness of 41 to 60 nm, excellent photoelectric conversion efficiencies of 12% or more can be obtained, In the case of Example 1, in which the fullerene derivative layer was formed to a thickness of 55 nm, the photoelectric conversion efficiency was as excellent as 13.42%.

On the other hand, Comparative Examples 1 to 5, which are solar cells deviating from the thickness range of the fullerene derivative layer according to the present invention, exhibited relatively low photoelectric conversion efficiency, and the thickness of the fullerene derivative layer In the case of Comparative Example 1, in which the fullerene derivative layer having a thickness of 40 nm was formed, the photoelectric conversion efficiency was as low as 1.70%. This is due to the problem that the perovskite layer located below the fullerene derivative layer and the second electrode located above the fullerene derivative layer are in direct contact with each other due to the thickness of the fullerene derivative layer being too thin to cause a leakage current.

In addition, the solar cell of Comparative Example 6 which does not include the lithium fluoride buffer layer has a photoelectric conversion efficiency of about 11.50%, which is about 14.3% p (13.42%) higher than the photoelectric conversion efficiency of the solar cell of Example 1 including 13.42% Respectively.

In general, organic light emitting devices (OLEDs) use an electrode containing lithium fluoride or cesium fluoride and a metal as a cathode. In the case of organic solar cells (OPVs), lithium fluoride or cesium fluoride The results show that the performance of the device is not significantly different depending on the presence or absence of the device.

However, it has been confirmed that the solar cell having the constitution according to the present invention exhibits excellent photoelectric conversion efficiency when lithium fluoride or cesium fluoride is used as the electron extracting layer.

As described above, the solar cell according to the present invention uses a perovskite layer having a dense structure, a very thick and uniform thickness as a photoactive layer, and a very thin fullerene derivative By forming the layer, excellent photoelectric conversion efficiency can be exhibited.

Further, by including an electron extraction layer made of lithium fluoride (LiF) or cesium fluoride, it is possible to exhibit more excellent photoelectric conversion efficiency.

Furthermore, the manufacturing method of the solar cell according to the present invention has an advantage that it can be easily manufactured through a solution process.

100: Solar cell
10: first electrode
20: hole extraction layer
30: photoactive layer
31: perovskite layer
32: Fullerene derivative layer
40: electron extraction layer
50: second electrode

Claims (13)

A first electrode;
A hole extraction layer formed on the first electrode;
A photoactive layer formed on the hole extracting layer;
An electron extraction layer formed on the photoactive layer; And
And a second electrode formed on the electron extraction layer,
Wherein the photoactive layer comprises a perovskite layer having a thickness of 250 to 400 nm and a fullerene derivative layer having a thickness of 41 to 60 nm, the perovskite being represented by the following formula (1) or (2)
Wherein the electron extraction layer comprises a photovoltaic cell comprising lithium fluoride (LiF) or cesium fluoride (CsF) in a thickness of 0.5 to 1 nm,

&Lt; Formula 1 >
AMX ₃
(In the formula 1,
A is a straight or branched chain alkyl or an alkali metal ion of the C _{1 -20} C _{1 -20} straight or branched chain alkyl, an amine group is substituted for,
M is ^{Cu 2 +, Ni 2 +,} Co 2 +, Fe 2 +, Mn 2 +, Cr 2 +, Pd 2 +, Cd 2 +, Ge 2 +, Sn 2 +, Pb 2 + or Yb ^{2 +} a ,
X is a halogen ion.)

(2)
A ₂ MX ₄
(In the formula (2)
A is a straight or branched chain alkyl or an alkali metal ion of the C _{1 -20} C _{1 -20} straight or branched chain alkyl, an amine group is substituted for,
M is ^{Cu 2 +, Ni 2 +,} Co 2 +, Fe 2 +, Mn 2 +, Cr 2 +, Pd 2 +, Cd 2 +, Ge 2 +, Sn 2 +, Pb 2 + or Yb ^{2 +} a ,
And X is a halogen ion).
The method according to claim 1,
The fullerene derivative PCBM ([6,6] -phenyl-C 61 -butyric acid methyl ester), PC 71 BM, Bis-PCBM, IC 60 MA (indene-C 60 monoadduct), IC 70 MA, IC 60 BA ( indene-C ₆₀ bisadduct), IC ₇₀ BA, BC ₆₀ MA (biindene-C ₆₀ monoadduct), and BC ₇₀ MA.
The method according to claim 1,
Wherein the second electrode is selected from the group consisting of aluminum (Al), calcium (Ca), silver (Ag), zinc (Zn), gold (Au), platinum (Pt), copper (Cu) &Lt; / RTI &gt; wherein the metal is one or more metals.
The method according to claim 1,
Wherein the hole extracting layer comprises a conductive polymer.
Forming a hole extraction layer on the first electrode (step 1);
A hole-injection layer formed in step 1, a perovskite layer having a thickness of 250 to 400 nm and a perovskite layer having a thickness of 41 to 60 nm, Forming an active layer (step 2);
(Step 3) of forming an electron extraction layer made of lithium fluoride (LiF) or cesium fluoride (CsF) in a thickness of 0.5 to 1 nm on the photoactive layer formed in step 2; And
And forming a second electrode on the electron extraction layer formed in step 3 (step 4).

&Lt; Formula 1 >
AMX ₃
(In the formula 1,
A is a straight or branched chain alkyl or an alkali metal ion of the C _{1 -20} C _{1 -20} straight or branched chain alkyl, an amine group is substituted for,
M is ^{Cu 2 +, Ni 2 +,} Co 2 +, Fe 2 +, Mn 2 +, Cr 2 +, Pd 2 +, Cd 2 +, Ge 2 +, Sn 2 +, Pb 2 + or Yb ^{2 +} a ,
X is a halogen ion.)

(2)
A ₂ MX ₄
(In the formula (2)
A is a straight or branched chain alkyl or an alkali metal ion of the C _{1 -20} C _{1 -20} straight or branched chain alkyl, an amine group is substituted for,
M is ^{Cu 2 +, Ni 2 +,} Co 2 +, Fe 2 +, Mn 2 +, Cr 2 +, Pd 2 +, Cd 2 +, Ge 2 +, Sn 2 +, Pb 2 + or Yb ^{2 +} a ,
And X is a halogen ion).
6. The method of claim 5,
The step of forming the photoactive layer of step 2 includes:
Preparing a perovskite precursor solution comprising an organic halide and a metal halide (step a);
(B) forming a perovskite layer having a thickness of 250 to 400 nm by applying the perovskite precursor solution prepared in step (a) on the hole extract layer; And
(C) forming a fullerene derivative layer having a thickness of 41 to 60 nm by applying a solution containing a fullerene derivative on the perovskite layer formed in the step b) Way.
The method according to claim 6,
Wherein the perovskite precursor solution in step (a) comprises a polar aprotic solvent.
8. The method of claim 7,
Wherein the polar aprotic solvent forms a solvate with an organic ion, a metal ion, a halogen ion and a complex ion thereof derived from an organic halide and a metal halide.
The method according to claim 6,
Wherein the organic halide of step (a) is a compound represented by the following formula (3):

(3)
AX
(3)
A is a straight or branched chain alkyl or an alkali metal ion of the C _{1 -20} C _{1 -20} straight or branched chain alkyl, an amine group is substituted for,
And X is a halogen ion).
The method according to claim 6,
Wherein the metal halide of step (a) is a compound represented by the following formula (4).

&Lt; Formula 4 >
MX ₂
(In the formula 4,
M is ^{Cu 2 +, Ni 2 +,} Co 2 +, Fe 2 +, Mn 2 +, Cr 2 +, Pd 2 +, Cd 2 +, Ge 2 +, Sn 2 +, Pb 2 + or Yb ^{2 +} a ,
And X is a halogen ion).
The method according to claim 6,
Wherein the molar ratio of the metal halide and the organic halide contained in the perovskite precursor solution in step (a) is 1: 1 to 2: 1.
A first electrode;
A hole extraction layer formed on the first electrode;
A photoactive layer formed on the hole extracting layer;
An electron extraction layer formed on the photoactive layer; And
And a second electrode formed on the electron extraction layer, the method comprising the steps of:
(A) preparing a perovskite precursor solution comprising an organic halide, a metal halide and a polar aprotic solvent;
(B) forming a perovskite layer having a thickness of 250 to 400 nm by applying the perovskite precursor solution prepared in step (a) on the hole extract layer; And
Forming a fullerene derivative layer having a thickness of 41 to 60 nm (step c) by applying a solution containing a fullerene derivative on the perovskite layer formed in the step b) to form a ferroelectric layer having a thickness of 250 to 400 nm A skylight layer and a 41 to 60 nm thick fullerene derivative layer,
Wherein the electron extraction layer is formed of lithium fluoride (LiF) or cesium fluoride (CsF) in a thickness of 0.5 to 1 nm.
A solar cell module comprising the solar cell of claim 1.

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