KR102212040B1 - Method of fabricating solar cell comprising buffer layer formed by atomic layer deposition - Google Patents

Abstract

The present invention comprises the steps of (a) forming a rear electrode layer on a substrate; (b) forming a light absorption layer on the rear electrode layer; (c) treating the surface of the oxide film of the light absorbing layer formed by exposing the light absorbing layer; (d) forming a buffer layer on the surface-treated light-absorbing layer oxide film by atomic layer deposition; And (e) forming a front electrode layer on the buffer layer.

Description

Manufacturing method of solar cell including buffer layer formed by atomic layer deposition {METHOD OF FABRICATING SOLAR CELL COMPRISING BUFFER LAYER FORMED BY ATOMIC LAYER DEPOSITION}

The present invention relates to a method of manufacturing a solar cell including a buffer layer formed by atomic layer deposition.

As a part of the development of new and renewable energy to reduce carbon emissions in accordance with recent environmental regulations, solar cells are attracting attention because they convert solar light into electric energy, so there is little restriction on the installation site and can easily generate electricity.

Such solar cells are manufactured using single crystal or polycrystalline silicon wafers, but in general, single crystal silicon has the highest photoelectric conversion efficiency and is widely used in large-scale power generation system fields. However, such single crystal silicon is uneconomical due to its complicated manufacturing process and high cost.

Therefore, although the efficiency is relatively inferior, a method of manufacturing a solar cell using polycrystalline silicon using a low-grade silicon wafer has been developed and is currently used in residential power generation systems. However, there is a limit to lowering the solar cell manufacturing cost due to the complicated process and the increase in raw material prices due to the recent surge in silicon prices.

Accordingly, in recent years, as a thin film solar cell to overcome this, a method of using amorphous silicon having a multi-junction structure and a method of using a compound semiconductor such as a chalcogenide compound have been developed.

The present invention comprises the steps of (a) forming a rear electrode layer on a substrate; (b) forming a light absorption layer on the rear electrode layer; (c) treating the surface of the oxide film of the light absorbing layer formed by exposing the light absorbing layer; (d) forming a buffer layer on the surface-treated light-absorbing layer oxide film by atomic layer deposition; And (e) forming a front electrode layer on the buffer layer.

However, the technical problem to be achieved by the present invention is not limited to the above-mentioned problems, and other problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

The present invention comprises the steps of (a) forming a rear electrode layer on a substrate; (b) forming a light absorption layer on the rear electrode layer; (c) treating the surface of the oxide film of the light absorbing layer formed by exposing the light absorbing layer; (d) forming a buffer layer on the surface-treated light-absorbing layer oxide film by atomic layer deposition; And (e) it provides a method of manufacturing a solar cell comprising the step of forming a front electrode layer on the buffer layer.

In step (b), the light absorbing layer is CuInS ₂ (CIS), CuGaS ₂ (CGS), CuInSe ₂ (CISe), CuGaSe ₂ (CGSe), CuAlSe ₂ (CASe), CuInTe ₂ (CITe), CuGaTe ₂ (CGTe) , Cu(In, Ga)S ₂ (CIGS), Cu(In, Ga)Se ₂ (CIGSe), Cu ₂ ZnSnS ₄ (CZTS) and one or more chalcogenide-based compounds selected from the group consisting of CdTe. have.

In step (c), the treatment of the surface of the oxide layer of the light absorbing layer may be performed by supplying at least one of a cleaning gas and a plasma.

The cleaning gas may be at least one selected from the group consisting of NH ₃ , ClF ₃ , F ₂ , H ₂ O, O ₂ , N ₂ O, NF ₃ and N ₂ .

The flow amount of the cleaning gas may be 30 sccm to 5000 sccm.

The flow time of the cleaning gas may be 1 minute to 60 minutes.

The plasma is formed by at least one reactive gas selected from the group consisting of Ar, N ₂ , O ₂ , H ₂ O, H ₂ , He, CH ₄ , NH ₃ , CF ₄ , C ₂ H ₂ and C ₃ H ₈ Can be.

The plasma flow time may be 1 minute to 30 minutes.

In step (c), the treatment of the surface of the oxide layer of the light absorbing layer may be performed at a temperature of 80°C to 160°C.

Step (c) and step (d) may be performed in-situ.

The O content of the light-absorbing layer oxide film surface-treated in step (d) may be 5 at% to 50 at%.

The thickness of the light-absorbing layer oxide film surface-treated in step (d) may be 10 nm or less.

In step (d), the buffer layer may be a Cd-free buffer layer.

In step (d), the buffer layer may be formed by repeatedly stacking atomic layers of Zn, S, Zn, and O.

In step (d), the band gap energy of the buffer layer may be 3.2 eV to 3.6 eV.

In step (d), the thickness of the buffer layer may be 3 nm to 100 nm.

In the solar cell according to the present invention, before forming the buffer layer by atomic layer deposition, the surface of the light-absorbing layer oxide film formed by exposing the light-absorbing layer is treated, thereby removing all the light-absorbing layer oxide film or reducing the thickness of the surface-treated light-absorbing layer oxide film to 10 nm. Hereinafter, preferably, it can be maintained at 3 nm or less, it is possible to prevent defects in the light absorbing layer, and it is possible to prevent Na diffusion into the buffer layer, thereby improving the performance of the solar cell to increase the photoelectric conversion efficiency of the solar cell. I can.

1 illustrates a method of manufacturing a solar cell including a buffer layer formed by an atomic layer deposition method according to an embodiment of the present invention.

In manufacturing a solar cell, the present inventors confirmed that the photoelectric conversion efficiency of the solar cell can be finally improved by treating the surface of the oxide film of the light absorbing layer formed by exposing the light absorbing layer before forming the buffer layer by the atomic layer deposition method. Was completed.

Hereinafter, the present invention will be described in detail.

The present invention comprises the steps of (a) forming a rear electrode layer on a substrate; (b) forming a light absorption layer on the rear electrode layer; (c) treating the surface of the oxide film of the light absorbing layer formed by exposing the light absorbing layer; (d) forming a buffer layer on the surface-treated light-absorbing layer oxide film by atomic layer deposition; And (e) it provides a method of manufacturing a solar cell comprising the step of forming a front electrode layer on the buffer layer.

In addition, the present invention is a substrate; A rear electrode layer formed on the substrate; A light absorption layer formed on the rear electrode layer; A buffer layer formed on the light absorption layer by atomic layer deposition; And a front electrode layer formed on the buffer layer, and the O content of the surface-treated light absorption layer oxide film formed between the light absorption layer and the buffer layer may be 5 at% to 50 at%.

Also, a substrate; A rear electrode layer formed on the substrate; A light absorption layer formed on the rear electrode layer; A buffer layer formed on the light absorption layer by atomic layer deposition; And a front electrode layer formed on the buffer layer, and a surface-treated light absorption layer oxide film formed between the light absorption layer and the buffer layer may have a thickness of 10 nm or less.

1 illustrates a method of manufacturing a solar cell including a buffer layer formed by an atomic layer deposition method according to an embodiment of the present invention.

As shown in FIG. 1, a method of manufacturing a solar cell including a buffer layer formed by atomic layer deposition according to an embodiment of the present invention includes the steps of: (a) forming a rear electrode layer on a substrate; (b) forming a light absorption layer on the rear electrode layer; (c) treating the surface of the oxide film of the light absorbing layer formed by exposing the light absorbing layer; (d) forming a buffer layer on the surface-treated light-absorbing layer oxide film by atomic layer deposition; And (e) forming a front electrode layer on the buffer layer.

(a): On the substrate Back electrode layer formation

In the present invention, step (a) is a step of forming a rear electrode layer on a substrate.

A glass substrate may be used as the substrate, and a ceramic substrate, a metal substrate, or a polymer substrate may be used.

For example, as a glass substrate, a soda lime glass or a high strained pointsoda glass substrate may be used, and a substrate containing stainless steel or titanium may be used as a metal substrate. As the substrate, a polyimide substrate may be used.

The substrate may be transparent. The substrate may be rigid or flexible.

In addition, the rear electrode layer is formed on the substrate, and may include a metal such as Mo as a conductive layer.

The rear electrode layer may be formed of a single layer, or may be formed of a plurality of layers of two or more layers. When the rear electrode layer is made of two or more layers, each of the layers may be formed of the same metal or different metals.

The formation of the back electrode layer may be by one or more known methods selected from the group consisting of sputtering, vacuum evaporation, chemical vapor deposition, atomic layer deposition, ion beam deposition, screen printing, spray dip coating, tape gasping, and inkjet.

The thickness of the rear electrode layer is preferably 0.1 μm to 1 μm, and more preferably 0.5 μm, but is not limited thereto.

(b): Light absorption layer formation

In the present invention, step (b) is a step of forming a light absorption layer on the rear electrode layer, and the light absorption layer is formed by depositing and heat treating a light absorption layer material on the rear electrode layer.

The light absorbing layer is a light absorbing layer material, such as CuInS ₂ (CIS), CuGaS ₂ (CGS), CuInSe ₂ (CISe), CuGaSe ₂ (CGSe), CuAlSe ₂ (CASe), CuInTe ₂ (CITe), CuGaTe ₂ (CGTe), It is preferable to include one or more chalcogenide-based compounds selected from the group consisting of Cu(In, Ga)S ₂ (CIGS), Cu(In, Ga)Se ₂ (CIGSe), Cu ₂ ZnSnS ₄ (CZTS) and CdTe However, it is not limited thereto.

The light absorbing layer material may be deposited by vacuum deposition or non-vacuum deposition. Specifically, the deposition of the light absorption layer material is by vacuum deposition, and may be by at least one method selected from the group consisting of sputtering, vacuum evaporation, chemical vapor deposition, atomic layer deposition, and ion beam deposition. The deposition is by non-vacuum deposition, and may be performed by one or more methods selected from the group consisting of screen printing, spray dip coating, tape gasping, and ink jet.

The heat treatment may occur simultaneously with the deposition of the light absorbing layer material, or may occur after the deposition of the light absorbing layer material.

In addition, the heat treatment may be performed under a Se atmosphere or an S atmosphere, and the heat treatment may be performed at 300° C. to 600° C. for 30 minutes to 1 hour.

For example, Cu, In, Ga, and Se precursors are deposited by a sputtering method, and heat-treated using H ₂ Se or H ₂ S gas in a heat treatment chamber to selenize to form Cu (In, Ga )S ₂ (CIGS) A light absorbing layer containing a chalcogenide compound may be formed, and a crucible containing Cu, In, Ga, and Se sources in a solid form is heated to heat treatment while simultaneously in a high vacuum atmosphere. It may be evaporated to form a light-absorbing layer including a Cu(In, Ga)S ₂ (CIGS) chalcogenide compound.

(c): Light absorbing layer Oxide film Surface treatment

In the present invention, step (c) is a step of treating the surface of the oxide film of the light absorbing layer formed by exposing the light absorbing layer.

By treating the surface of the light-absorbing layer oxide film, the entire light-absorbing layer oxide film may be completely removed, and the thickness of the surface-treated light-absorbing layer oxide film may be kept at 10 nm or less, preferably 3 nm or less. In this case, when the thickness of the surface-treated light-absorbing layer oxide film exceeds the above range, defects in the light-absorbing layer occur and Na diffusion into the buffer layer cannot be prevented.

Before forming the buffer layer by the atomic layer deposition method, which is a kind of dry method, the light absorption layer is exposed to outside air such as an atomic layer deposition (ALD) oxidizer, H ₂ O, H ₂ O ₂ , O _3, and the formation of the light absorbing layer oxide film is inevitable. . By treating the surface of the light-absorbing layer oxide film, the entire light-absorbing layer oxide film can be removed, or the thickness of the surface-treated light-absorbing layer oxide film can be maintained at 10 nm or less, preferably 3 nm or less, and defects in the light absorption layer can be prevented. , There is an advantage of preventing diffusion of Na into the buffer layer.

The treatment of the surface of the oxide layer of the light absorption layer may be performed by supplying at least one of a cleaning gas and a plasma. At least one of the cleaning gas and plasma serves to remove the entire light-absorbing layer oxide film or to treat the surface of the light-absorbing layer oxide film so that the thickness of the surface-treated light-absorbing layer oxide film is 10 nm or less, preferably 3 nm or less. do.

The cleaning gas is preferably at least one selected from the group consisting of NH ₃ , ClF ₃ , F ₂ , H ₂ O, O ₂ , N ₂ O, NF ₃ and N _2, and consisting of NH ₃ , ClF ₃ and F ₂ More preferably one or more selected from the group, but is not limited thereto.

The flow amount of the cleaning gas is preferably 30 sccm to 5000 sccm, but is not limited thereto. At this time, the flow amount of the cleaning gas is determined according to the size of the chamber, and if the flow amount of the cleaning gas is less than 30 sccm, there is a problem that the etching uniformity is poor due to a trace amount of cleaning gas. In this case, a turbulence gas flow is formed due to excessive gas injection, resulting in poor etching uniformity, and there is a problem in that the performance of the solar cell is deteriorated due to excessive etching of the oxide film of the light absorption layer.

The flow time of the cleaning gas is preferably 1 minute to 60 minutes, but is not limited thereto. At this time, the flow time of the cleaning gas is determined according to the size of the chamber, and if the flow time of the cleaning gas is less than 1 minute, there is a problem that the etching uniformity is poor due to a small amount of cleaning gas, and the flow time of the cleaning gas is reduced. If it exceeds 60 minutes, there is a problem in that the performance of the solar cell is deteriorated due to excessive etching of the oxide film of the light absorption layer.

Plasma means that gaseous molecules absorb a certain amount of high energy and exist as electrical particles (anions, cations, electrons, radicals) and electrically neutral particles. It exists in a state of high energy reactivity and has a property of reacting quickly with other substances.

The plasma is formed by at least one reactive gas selected from the group consisting of Ar, N ₂ , O ₂ , H ₂ O, H ₂ , He, CH ₄ , NH ₃ , CF ₄ , C ₂ H ₂ and C ₃ H ₈ It is preferable to be, and more preferably formed by a mixed reaction gas consisting of Ar and N ₂ , but is not limited thereto.

Specifically, the plasma is at least one selected from the group consisting of Ar, N ₂ , O ₂ , H ₂ O, H ₂ , He, CH ₄ , NH ₃ , CF ₄ , C ₂ H ₂ and C ₃ H ₈ in the chamber. The reaction gas or a mixed reaction gas consisting of Ar and N ₂ is supplied and then power is applied to generate a vacuum or atmospheric pressure, but is not limited thereto.

In addition, the plasma flow time is preferably 1 to 30 minutes, but is not limited thereto. At this time, when the plasma flow time is less than 1 minute, there is a problem that the etching uniformity is poor due to insufficient etching of the light absorbing layer oxide film, and when the plasma flow time exceeds 30 minutes, excessive ion bombardment There is a problem in that the performance of the solar cell is deteriorated due to excessive etching of the oxide film of the light absorbing layer due to.

The treatment of the surface of the oxide film of the light absorbing layer is most efficient when cleaning gas and plasma are simultaneously supplied.

The treatment of the surface of the oxide film of the light absorption layer is preferably performed at a temperature of 80°C to 160°C, but is not limited thereto. At this time, when the treatment of the surface of the light-absorbing layer oxide film is performed at a temperature of less than 80°C, there is a problem that the light-absorbing layer oxide film is not etched or only partially etched due to poor reactivity of at least one of the cleaning gas and plasma and the light-absorbing layer oxide film , When the treatment of the surface of the light-absorbing layer oxide film is performed at a temperature exceeding 160°C, the performance of the solar cell decreases due to excessive etching of the light-absorbing layer oxide film due to excessive reactivity of at least one of the cleaning gas and plasma and the light-absorbing layer oxide film. There is a problem.

The treatment of the surface of the oxide film of the light absorption layer may be performed once, or the treatment of the surface of the oxide film of the light absorption layer and the formation of the buffer layer may be alternately performed several times.

The treatment of the surface of the light absorbing layer oxide film and the formation of the buffer layer may be performed separately in different devices, but in-situ operation is more preferable in terms of process efficiency and cost reduction.

The O content of the surface-treated light-absorbing layer oxide film is preferably 5 at% to 50 at%, but is not limited thereto. At this time, the O content of the surface-treated light-absorbing layer oxide film is maintained in the above range, thereby preventing defects in the light-absorbing layer, preventing Na diffusion into the buffer layer, reducing the shunt path, and reducing the series resistance of the solar cell. There is an advantage in that it is possible to prevent a decrease in efficiency due to the formation of the oxide film of the light absorbing layer by reducing the (series resistance).

The O content of the surface-treated light-absorbing layer oxide film as described above is 5 at% to 50 at%, the surface-treated light-absorbing layer oxide film is analyzed through XPS (X-ray photoelectron spectroscopy) and AES (Augar electron spectroscopy). It can be confirmed by doing. Specifically, when the surface-treated light-absorbing layer oxide film is formed, the SeO ₂ peak area in the binding energy [eV] increases, the Se-Se peak area decreases, and the Augar kinetic energy is compared to the case where the light-absorbing layer oxide film is not formed at all. [eV] phase Cu peak moves in the direction of high binding energy.

(d): Buffer layer Atomic layer Formed by evaporation

In the present invention, step (d) is a step of forming a buffer layer on the surface-treated light-absorbing layer oxide film by atomic layer deposition.

The buffer layer is formed on the surface-treated light absorbing layer oxide film, and may be formed of at least one layer. In this case, the buffer layer is an n-type semiconductor layer, and the light absorption layer is a p-type semiconductor layer. Accordingly, the light absorption layer and the buffer layer form a pn junction. Since the light absorption layer and the front electrode layer have a large difference between a lattice constant and an energy band gap, a good junction can be formed by inserting the buffer layer having a band gap between the two materials.

Conventionally, the buffer layer is mainly formed of CdS or the like by chemical bath deposition (CBD), but this causes contamination, which has an environmental problem.

Accordingly, in the present invention, the conventional problem is solved by using a Cd-free buffer layer formed by atomic layer deposition (ALD) on the surface-treated light absorbing layer oxide film as the buffer layer.

By surface-treating the light-absorbing layer oxide film, the surface characteristics of the light-absorbing layer were improved by minimizing the thickness of the surface-treated light-absorbing layer oxide film.The buffer layer formed thereon has an advantage in that it is easy to control composition, thickness, and growth rate.

The buffer layer is characterized by excluding CdS, and is preferably a Cd-free buffer layer, but is not limited thereto. That is, the Cd-free buffer layer refers to a buffer layer that does not contain cadmium so that an eco-friendly process that is not subject to environmental regulations is possible.

When the buffer layer is a Cd-free buffer layer and includes a composition of Zn(O, S), atomic layers of Zn, S, Zn, and O may be repeatedly stacked by atomic layer deposition. In this case, the molar ratio of O:S in the buffer layer may be 3:1 to 10:1.

The band gap energy of the buffer layer is preferably 3.2 eV to 3.6 eV, more preferably 3.25 eV to 3.55 eV, but is not limited thereto. When the buffer layer contains only the composition of ZnO, the bandgap energy is 3.2 eV, and when the buffer layer contains only the composition of ZnS, the bandgap energy is 3.6 eV. The above range by adjusting the molar ratio of O:S in the buffer layer May have a bandgap energy of

The thickness of the buffer layer is preferably 3 nm to 100 nm, more preferably 3 nm to 50 nm, but is not limited thereto. At this time, when the thickness of the buffer layer is less than the above range, the buffer layer is not formed uniformly, so that a portion in contact with the front electrode layer and the light absorbing layer is generated, thereby reducing the photoelectric conversion efficiency, and the thickness of the buffer layer exceeds the above range. In this case, there is a problem in that the transmittance of the buffer layer decreases and the amount of light entering the light absorption layer decreases, thereby reducing the light conversion efficiency. In particular, by forming the buffer layer to have a thickness of 50 nm or less, there is an effect of improving throughput and a capacity-up during a manufacturing process.

(e): The front electrode layer formation

The front electrode layer is formed on the buffer layer, and the front electrode layer is a window layer that forms a pn junction with the light absorbing layer, and is made of ZnO, aluminum (Al) or alumina (Al ₂ O ₃ ) by sputtering or the like. It may be formed of doped ZnO, ITO, or the like.

The front electrode layer may have a double structure in which an n-type ZnO thin film having excellent electro-optical properties or an indium tin oxide (ITO) thin film is deposited on an i-type ZnO thin film.

The thickness of the i-type ZnO thin film is preferably 10 nm to 70 nm, more preferably 40 nm to 50 nm, but is not limited thereto. In addition, the thickness of the n-type ZnO thin film or ITO (Indium Tin Oxide) thin film is preferably 250 nm to 1000 nm, more preferably 500 nm to 1000 nm, but is not limited thereto.

At this time, since the i-type ZnO thin film functions as a transparent electrode on the front surface of the solar cell, it has high light transmittance and good electrical conductivity, and is preferably formed of an undoped ZnO thin film. In addition, the n-type ZnO thin film deposited on the i-type ZnO thin film has a low resistance value by doping ZnO with aluminum (Al) or alumina (Al ₂ O ₃ ), and the production cost compared to the ITO (Indium Tin Oxide) thin film. It is low and has an economic advantage.

The solar cell according to the present invention treats the surface of the oxide film of the light-absorbing layer formed by exposing the light-absorbing layer before forming the buffer layer by atomic layer deposition, so that the thickness of the surface-treated light-absorbing layer oxide film is 10 nm or less, preferably 3 nm or less. It can be maintained as, defects in the light absorption layer can be prevented, and Na diffusion into the buffer layer can be prevented, thereby improving the performance of the solar cell, thereby increasing the photoelectric conversion efficiency of the solar cell.

Hereinafter, a preferred embodiment is presented to aid the understanding of the present invention. However, the following examples are provided for easier understanding of the present invention, and the contents of the present invention are not limited by the following examples.

[ Example ]

Example One

The Mo-based alloy prepared on a sodalime glass substrate was coated by DC sputtering to form a 0.5 μm rear electrode layer. After depositing Cu, In, Ga, and Se precursors on the rear electrode layer by DC sputtering, heat treatment was performed at 550° C. for 30 to 60 minutes in a Se atmosphere to form a light absorbing layer containing a CIGS-based compound of 2 μm. Thereafter, the light-absorbing layer is exposed to the outside air to form a light-absorbing layer oxide film, and the surface of the light-absorbing layer oxide film is 50 × 50 × 50 ㎣ ~ 1000 × 1000 × 1000 ㎣ volume of the cleaning gas of the chamber consisting of NH ₃ flow 50 ~ It was supplied under conditions of 1000 sccm, flow time 1-60 minutes and treated at 80-160°C (50 x 50 x 50 mm3 volume chamber: flow volume 50 sccm, flow time 1 minute /1000 x 1000 x 1000 mm 3 volume chamber: flow volume 1000 sccm , Flow time 60 minutes). A 40 nm Zn(O, S) buffer layer was formed on the light absorption layer oxide film by atomic layer deposition, and then coated by RF sputtering to form a 50 nm i-type ZnO thin film and 1000 nm n-type ZnO thin film to form a front electrode layer. The cell was finally prepared.

Example 2

It was the same as in Example 1, except that the cleaning gas of the chamber made of ClF ₃ was supplied under the conditions of a flow amount of 50 to 1000 sccm and a flow time of 1 to 60 minutes.

Example 3

It was the same as in Example 1, except that the cleaning gas of the chamber consisting of F ₂ was supplied under the conditions of a flow amount of 50 to 1000 sccm and a flow time of 1 to 60 minutes.

Example 4

In the same manner as in Example 1, except that the plasma formed by the reaction gas in the chamber consisting of Ar and N ₂ instead of the cleaning gas was supplied under the condition of a flow time of 1 to 60 minutes.

Example 5

It was the same as in Example 1, except that the plasma formed by the reaction gas in the chamber consisting of Ar and N ₂ was additionally supplied under the condition of a flow time of 1 to 60 minutes.

Comparative example One

It was the same as in Example 1, except that the surface treatment of the light-absorbing layer oxide film was not performed at all.

Experimental example

(One) Light absorbing layer Oxide Thickness measurement

The thickness of the light-absorbing layer oxide film surface-treated according to Examples 1 to 5 and the thickness of the light-absorbing layer oxide film that was not surface-treated according to Comparative Example 1 were observed with a bright field transmission electron microscope (BF-TEM), and the results are shown in the following table. It is shown in 1.

division Thickness (nm) Example 1 <3nm Example 2 <3nm Example 3 <3nm Example 4 <3nm Example 5 <3nm Comparative Example 1 15nm

As shown in Table 1, in the case of Examples 1 to 5, it was confirmed that the thickness of the light-absorbing layer oxide film was thinner compared to Comparative Example 1.

(2) Evaluation of solar cell performance and photoelectric conversion efficiency

The open-circuit voltage (V _oc ), short-circuit current density (J _sc ), charging factor (FF), and photoelectric conversion efficiency (η) of the solar cells manufactured according to Examples 1 to 5 and Comparative Example 1 were evaluated, and the result was It is shown in Table 2.

division V _oc
(mV) J _sc
(mA/㎠) FF
(%) η
(%) Example 1 610 35 63 13.5 Example 2 610 35 63 13.5 Example 3 610 35 63 13.5 Example 4 610 35 63 13.5 Example 5 610 35 63 13.5 Comparative Example 1 630 30 35 6.6

As shown in Table 2, in the case of Examples 1 to 5, it was confirmed that the short circuit current density (J _sc ), charging factor (FF), and photoelectric conversion efficiency (η) of the solar cell were all higher than that of Comparative Example 1. .

The above description of the present invention is for illustrative purposes only, and those of ordinary skill in the art to which the present invention pertains will be able to understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not limiting.

Claims (16)

(a) forming a rear electrode layer on the substrate;
(b) forming a light absorption layer on the rear electrode layer;
(c) treating the surface of the oxide layer of the light absorbing layer formed by exposing the light absorbing layer to remove a partial thickness of the oxide layer of the light absorbing layer;
(d) forming a buffer layer on the surface-treated light-absorbing layer oxide film by atomic layer deposition; And
(e) forming a front electrode layer on the buffer layer,
In step (c), the treatment of the surface of the oxide layer of the light absorption layer is performed by supplying at least one of a cleaning gas and a plasma,
The cleaning gas is at least one selected from the group consisting of NH ₃ , ClF ₃ and F ₂ ,
The flow amount of the cleaning gas is 30 sccm to 5000 sccm, the flow time of the cleaning gas is 1 minute to 60 minutes,
The thickness of the light-absorbing layer oxide film surface-treated in step (d) is 3 nm or less,
Solar cell manufacturing method.
The method of claim 1,
In step (b), the light absorbing layer is CuInS ₂ (CIS), CuGaS ₂ (CGS), CuInSe ₂ (CISe), CuGaSe ₂ (CGSe), CuAlSe ₂ (CASe), CuInTe ₂ (CITe), CuGaTe ₂ (CGTe) , Cu(In, Ga)S ₂ (CIGS), Cu(In, Ga)Se ₂ (CIGSe), Cu ₂ ZnSnS ₄ (CZTS) and CdTe containing one or more chalcogenide-based compounds selected from the group consisting of
Solar cell manufacturing method.
delete delete delete delete The method of claim 1,
The plasma is formed by at least one reactive gas selected from the group consisting of Ar, N ₂ , O ₂ , H ₂ O, H ₂ , He, CH ₄ , NH ₃ , CF ₄ , C ₂ H ₂ and C ₃ H ₈
Solar cell manufacturing method.
The method of claim 1,
The plasma flow time is 1 minute to 30 minutes
Solar cell manufacturing method.
The method of claim 1,
In the step (c), the treatment of the surface of the oxide layer of the light absorbing layer is performed at a temperature of 80°C to 160°C.
Solar cell manufacturing method.
The method of claim 1,
Step (c) and step (d) are performed in-situ
Solar cell manufacturing method.
The method of claim 1,
The O content of the light-absorbing layer oxide film surface-treated in step (d) is 5 at% to 50 at%.
Solar cell manufacturing method.
delete The method of claim 1,
In step (d), the buffer layer is a Cd-free buffer layer.
Solar cell manufacturing method.
The method of claim 1,
In the step (d), the buffer layer is that the atomic layers of Zn, S, Zn, and O are repeatedly stacked.
Solar cell manufacturing method.
The method of claim 1,
The band gap energy of the buffer layer in the step (d) is 3.2 eV to 3.6 eV.
Solar cell manufacturing method.
The method of claim 1,
The thickness of the buffer layer in step (d) is 3 nm to 100 nm.
Solar cell manufacturing method.

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