WO2013168845A1

WO2013168845A1 - Target for light absorbing layer of thin film solar cell, method for manufacturing same and thin film solar cell

Info

Publication number: WO2013168845A1
Application number: PCT/KR2012/003960
Authority: WO
Inventors: 조용수; 조연화; 연득호
Original assignee: 연세대학교 산학협력단
Priority date: 2012-05-11
Filing date: 2012-05-18
Publication date: 2013-11-14
Also published as: KR20130126170A; KR101418831B1

Abstract

The present invention provides a method for manufacturing a target to be used in depositing a CZTSe(Cu-Zn-Sn—Se)-based light absorbing thin film of a solar cell. The method comprises: (1) a step of preparing Cu, Zn, Sn and Se powder at a mole ratio of 2+α:1+β:1:4; (2) a step of introducing the Cu, Zn, Sn and Se powder and metal balls into a container and stirring the powder to synthesize CZTSe material by mechanical force; (3) a step of pressurizing and firing the synthesized CZTSe material to produce pellets having shapes corresponding to the shape of the target; and (4) a step of performing a heat treatment on the produced pellets to produce a final single CZTSe target. The final single CZTSe target has a composition of Cu(_2+a)Zn(_1+β)SnSe₄ (0≤α<1, 0≤β≤1, where at least one of α and β is larger than zero).

Description

[Specification】

[Name of invention]

Target for light absorption layer of thin film solar cell, manufacturing method thereof and thin film solar cell

[Technical Field]

The present invention relates to the manufacture of a target, and more particularly, a target for use in forming a Cu2ZnSnSe ₂ (CZTSe) based thin film instead of a CuInSe ₂ (CIS) based material commonly used as a light absorbing layer thin film of a thin film solar cell. The target manufacturing method and the said thin-film solar cell.

[Background]

Thin-film solar cells are much thinner than Si wafer-based cells, can form thin films over large areas at lower temperatures, and can be manufactured at lower cost. As the light absorption layer of the thin film solar cell, a thin film made of CIS or CIGS (CuInGaSe ₂ ) material is used. CIS or CIGS series solar cells have been selected as potential candidates to replace Si solar cells due to the high efficiency that is equivalent to that of Si solar cells and the relatively low cost of materials. Recently, despite the promising properties of the CIS or CIGS-based materials, research into a new light-absorbing layer of a thin-film solar cell is being attempted to replace this, in particular, with the expectation that the supply of In elements from mineral resources will be very limited. . Representatively, manufacture of solar cells in which Cu ₂ ZnSnSe ₄ (CZTSe) and Cu ₂ ZnSnS ₄ ) (CZTS) thin films are formed as a light absorption layer has been attempted. Although a solution process may be used to prepare the absorbing layer of the CZTSe solar cell, it is advantageous to use a sputtering method to form an effective and high quality thin film for large area production. In this case, conventionally, the thin film was formed through simultaneous or sequential deposition using two or more individual targets of Cu, Zn, Sn, Se, or a bicomponent compound. In the sputtering method, ᅳ layers of ions are deposited on each target, and a small amount of material is separated from the target by the force, and the separated material is deposited on a desired substrate. Existing methods that are now known to be successful have not escaped the notion of spurring with multiple individual targets. In addition, since a plurality of targets are used instead of a single target, it is difficult to control the composition of the finally formed thin film and to produce a uniform film. In addition, since a large number of targets have to be manufactured, it is expensive and hassle to take a complicated process. The reason why a single target was not successful is that each element generated in the sputtering process is separated by a different amount, thereby maintaining the molar ratio between the desired elements during the deposition process. Because it was difficult.

Detailed description of the invention

[Technical problem]

The present invention is to solve the above-mentioned problems of the prior art, a single target of Cu-Zn-Sn-Se component for forming a light absorption layer thin film of a three thin film solar cell, a method of manufacturing the same, and the light formed using the target An object of the present invention is to provide a thin film solar cell including an absorbing layer.

Another object of the present invention includes a target of Cu—Zn—Sn-Se component and a method for manufacturing the same, the light absorbing layer formed using the target, having a composition which does not form a secondary phase when forming a thin film despite a single target. It is an object to provide a thin film solar cell.

[Technical solution] ^■ ·

In order to achieve the above object, according to the present invention, there is provided a target manufacturing method for use in depositing a CZTSe (Cu—Zn—Sn-Se) based light absorbing layer thin film of a solar cell. The method comprises the steps of (1) preparing Cu, Zn, Sn and Se powders at a molar ratio of 2 + α: 1 + β: 1: 4, and (2) preparing the Cu, Zn, Sn and Se powders and metal balls. Putting into a container and stirring, synthesizing the CZTSe material by mechanical force, (3) pressing and firing the synthesized CZTSe material into pellets of a shape corresponding to the target shape, and (4) Heat-treating the prepared pellets to produce a final CZTSe single target, wherein the final CZTSe single target is Cu _{(2 +} a) Zn (i + p) SnSe ₄ (0 ≦ α <1, 0 < β <1, wherein at least one of a and β is larger than 0). In one embodiment, a and β may be 0 ≦ α ≦ 0.5, 0 ≦ β ≦ 0.5, provided that at least one of a and β is greater than 0, preferably a and β are both to be. In one embodiment, the synthesis of the CZTSe material in the step (2) can be carried out at room temperature and pressure. In one embodiment, in the step (4), the heat treatment may be performed at a silver and atmospheric pressure of about 300 ° C. In one embodiment, the Ge powder in step (1) is further added to the molar ratio of Sn: Ge = lx: x, and the CZTGeSe single target is prepared through the steps (2) to (4). In addition, the CZTGeSe single target is characterized by having a composition of Ciu c Znu + i ^ S — _x Ge _x Se ₄ (0 <x <l). According to another aspect of the invention, there is provided a single target for use in depositing a CZTSe (Cu—Zn—Sn—Se) based light absorbing layer thin film of a solar cell, wherein the single target is Cu _{(2 + a)} Zn _{( 1 +} P) SnSe ₄ (0 <α <1, 0 <β <1, wherein at least one of α and β is larger than 0). In one embodiment, α and β may be 0 ≦ α ≦ 0.5 and 0 <β ≦ 0 · 5, provided that at least one of α and β is greater than zero. In one embodiment, the single target further comprises Ge, and the Ge-containing CZTSe single target is characterized in that the composition of Cu ^ + c Znd + Sn-x Ge x Se ^ CK l). According to another aspect of the invention, providing a substrate, forming a lower electrode on the substrate, and forming a CZTSe (Cu-Zn-Sn—Se) based light absorbing layer thin film on the lower electrode And forming a buffer layer to reduce a band gap energy difference on the light absorbing layer thin film, and forming a metal grid and an upper electrode on the buffer layer, wherein the CZTSe-based light absorbing layer thin film includes: Provided is a solar cell comprising a composition of Cu _{(2 + a)} Zn ₍ i _{+ P)} SnSe4 (0 ≦ α <1, 0 <β <1, wherein at least one of a and β is greater than 0) do. In one embodiment, the light absorbing layer thin film is CZTSe single having a composition of Cu ^ + cZn _d + SnS (0 <α <1, 0 <β ≤ 1. At least one of α and β is greater than 0) The target can be formed by sputtering. In one embodiment, the CZTSe single target comprises (1) preparing Cu, Zn, Sn and Se powders at a molar ratio of 2 + α: 1 + β: 1: 4, and (2) the Cu, Zn, Sn and Se powder and a metal ball in a container and stirring, synthesizing the CZTSe material by mechanical force, (3) pressurized and calcined the synthesized CZTSe material pellets shaped to the target shape The step of preparing to, and (4) can be prepared through the step of heat-treating the prepared pellets to produce a final CZTSe single target. In one embodiment, a and β may be 0 ≦ α <0.5, 0 <β <0.5, provided that at least one of a and β increases greater than zero. In one embodiment, the synthesis of the CZTSe material in the step (2) can be carried out at room temperature and pressure. In one embodiment, the heat treatment in the step (4) may be carried out at a temperature and atmospheric pressure of about 30CTC.

In one embodiment, the Ge powder in step (1) is further added to the molar ratio of Sn: Ge = lx: x to prepare a CZTGeSe single target through the steps of (2) to (4) Further comprising, the CZTGeSe single target is characterized in that having a composition of Cu + coZrm + Sm-xGexSe O x ^). In one embodiment, after forming the light absorbing layer thin film, after heat treatment with additional Se pellets and then heat treatment in the H ₂ S / N ₂ atmosphere or after forming the light absorbing layer thin film, H ₂ Heat treatment in an S / N ₂ atmosphere may further include the step of including sulfur in the light absorbing layer thin film. In one embodiment, the sulfur may be included in the thin film by substituting Se of the light absorbing layer thin film after the heat treatment. According to another aspect of the present invention, a substrate, a lower electrode formed on the substrate, a CZTSe (Cu ᅳ Zn-Sn-Se) based light absorbing layer thin film formed on the lower electrode, and formed on the light absorbing layer thin film A buffer layer, which serves to alleviate the band gap energy difference, and an upper electrode and a metal grid sequentially formed on the buffer layer, wherein the CZTSe-based light absorbing layer thin film is formed of Cu ( _{2 +} a) Zn (i ₊ i3) SnSe4 ( 0 <α <1, 0 <β <1, provided that at least one of a and β is greater than 0). In one embodiment, the light absorbing layer thin film is Cu ( _{2 +} a) Zn (i ₊ p) Sn Se ₄ (0≤α <1, 0 <β <1, provided that at least one of a and β is greater than 0) It can be formed by sputtering a CZTSe single target having a composition of greater than, preferably a and β are 0≤α≤0.5, 0≤β≤0.5 (where at least one of a and β is greater than 0) . In one embodiment, the light absorbing layer thin film further comprises Ge, wherein the CZTSe light absorbing thin film containing Ge is Cu ₍ 2 _{+ a} ) Zn ₍ i _{+ P)} S — _x Ge _x Se 4 (0 <x It is characterized by having a composition of <l). In one embodiment, the light absorbing layer thin film may be further heat-treated in the H ₂ S / N ₂ atmosphere.

Advantageous Effects According to the target manufacturing method according to the invention, the solar cell is used as a light absorption layer

As a target for forming a CZTSe series thin film, a single target is provided instead of each individual target. Therefore, as compared with the case of forming a thin film by sputtering individual targets, the composition of the thin film can be more easily controlled, the process can be simplified, and the cost can be reduced. In addition, the single target of the present invention can be provided in a low-cost process hard, does not require high pressure or high vacuum required in the manufacture of a general target, it can be expected to further reduce the cost.

[Brief Description of Drawings]

1 is a view showing the optical properties of the CZTSe thin film prepared by sputtering the CZTSe target prepared according to an embodiment of the present invention.

2 is a micrograph showing the microstructure of a thin film when the Zn content of the CZTSe tablet is changed.

FIG. 3 is a graph showing XRD diffraction patterns and atomic ratio measurement results of CZTSe thin films including various contents of Zn.

4 is a view showing the shape according to the heat treatment temperature of the CZTSe thin film formed by increasing the Cu content of the CZTSe target to 2.5.

FIG. 5 is a view illustrating I V characteristics of a Cu ^ Z .sSnS thin film solar cell formed according to an exemplary embodiment of the present invention.

6 is a micrograph of a CZTGeSe thin film solar cell formed by including Ge according to one embodiment of the present invention.

7 is a view showing the microstructure change of the thin film as the content of Ge increases. 8 is a view showing the optical properties of the CZTGeSe thin film.

9 is a view showing the optical properties of the CZTSSe thin film.

Best Mode for Invention and Implementation

Hereinafter, with reference to the accompanying drawings will be described a preferred embodiment of the present invention. In the following description, descriptions of generally known configurations such as solar cells are omitted. Even if this description is omitted, those skilled in the art will be able to easily understand the features of the present invention through the following description. The present inventors studied a process of manufacturing a CZTSe-based solar cell, a light absorbing layer, that is, a CZTSe thin film, which is a core layer of a solar cell, by a method different from the conventional method. According to the conventional method, a CZTSe thin film is formed on a predetermined substrate by sputtering simultaneously or sequentially a material constituting the CZTSe thin film, that is, Cu, Zn, Sn, Se, or a two-component compound. However, this method is, as described above, the composition of the thin film finally formed It is difficult to control the cost and the complexity of the process makes it difficult to manufacture a low-cost thin film. In order to solve this problem, the present inventors have attempted to manufacture a single target consisting of Cu, Zn, Sn, and Se instead of individual targets. Specifically, first, each material that will constitute the CZTSe thin film, that is, Cu, Zn, Sn, Se material (powder) is prepared according to a predetermined molar ratio (for example, 2: 1: 1: 4), and then zirconia It was placed in a vessel with a ball and stirred with a strong force (ball milling). In this process, as the Cu, Zn, Sn, Se materials are continuously divided by the collision with the ball, the surface area becomes wider, and CZTSe material mixing is possible without applying a large force. This mixing process was performed at room temperature and atmospheric pressure. Subsequently, the inventors manufactured the CZTSe target using the CZTSe material made according to the above procedure. That is, the target used for sputtering is in the form of a hard disk, and the CZTSe material produced according to the above process is still in powder form. In order to produce such a powder-like material in a hard target form, high silver and high vacuum are required, but in this case, there is a problem in that the manufacturing cost increases. The inventors have found that hard CZTSe targets can be produced without high temperature and high vacuum processes. That is, the synthesized CZTSe material is further pressurized and fired through a press to prepare a pellet, and then pellets are heat-treated at 300 ° C. for 1 hour at atmospheric pressure in a nitrogen atmosphere. CZTSe target was produced by the process. This is because the melting point of Se is about 217 ^° C, and the heat treatment process Se of about 300 ^° C is melted, and it is thought to be connected between the particles of the CZTSe material. In addition, in the case of the CuSe phase, since it can be synthesized at about 250 ^° C., it is thought that a phase is formed in the sintering process and eventually a hard target is formed. The inventors formed a CZTSe thin film (i2ZnSnSe4) on a predetermined substrate through a PVD process using the CZTSe target prepared by the above process (i2ZnSnSe4), and measured the optical properties of the thin film. The results are shown in FIG. As shown in FIG. 1, the optical properties of the transmittance, photon energy vs ahv, and photoluminescence intensity according to wavelength of the CZTSe thin film are substantially the same as those of the CZTSe thin film formed according to the conventional method. Confirmed. That is, it was confirmed that the CZTSe thin film can be formed as a light absorption layer on a predetermined substrate by using the CZTSe single target prepared according to the present invention. On the other hand, the present inventors produced a target by changing the amount of zinc (Zn) of the CZTSe target, and then observed the properties of the thin film by forming a CZTSe thin film using each target. The results are shown in FIG. 2 shows micrographs of thin films of the composition Cu ₂ Zn _x SnSe ₄ (x = l, 1.5, 2). The picture on the left is a cross-sectional picture of the deposited CZTSe thin film formed at 10 mTor ^ 2 mTorr, respectively, and the picture on the right shows a cross-sectional picture after annealing heat treatment of the thin film at 50 (55 (rc for about 30 minutes). As can be seen from Fig. 2, as the amount of Zn increases, the thinner the film becomes and the grain size becomes larger, that is, the more preferable thin film properties are shown. The XRD diffraction pattern and atomic ratio of the thin film stones were measured, and the results are shown in FIG. 3 (The thin film is formed on a Mo-coated glass substrate, which is a substrate commonly used in thin film solar cells. As shown in Fig. 3, when Zn is included in the molar ratio of CZTSe thin film deposition 1, it can be seen that a second phase, SnS¾, is prominent. Increases with decreasing the amount of the second phase such as SnSe _2, and particularly in the case of 2Zn, second phase atda not observed. In particular, as can be observed in the right figure, in the thin film relative As the Zn amount is increased It can be seen that the ratio of Zn also increases, and in the case of 1.5Zn, it exhibits almost stoichiometric atomic ratio, and thus a preferable thin film composition, so when constructing a CZTSe target, the content range of Zn is different from other elements. The molar ratio is included in the range of 1 <Ζη≤2, preferably in the range of 1 <.η <1.5, on the other hand, the inventors added a Cu content in the CZTSe single target to observe a change in its properties. Figure 4 is a micrograph showing a form of a thin film according to a CZTSe thin film formed by adding a 2.5 mole ratio _{_{_{(Cu 2. 5 Zni. 5}}} SnSe 4) the silver foil film annealing heat treatment Cu. samples of both the CZTSe This appeared, showed little signs on MoS¾, SnSe _2, SnSe, ZnSe and the like of the second phase was not observed. On the other hand, in the case of annealing heat treated samples at 530 ° C, it can be seen that the microstructure and electrical properties are improved, which means that the heat treatment temperature makes a certain contribution to the properties of the thin film. In addition, although not specifically illustrated, as the amount of Cu added increases, the microstructure of the thin film showed a dense structure. In addition, when Cu is included in a molar ratio of ₂ , a second phase such as SnSe ₂ , SnSe, ZnSe is observed, and when it is included in a molar ratio of 3, a second phase such as some CuSe is observed (not shown). However, for 2.5Cu, no second phase was observed. That is, similarly to Zn, Cu was further included to form a thin film of a preferred composition with respect to the second phase. Therefore, Cu is included in the range of 2 <Cu <3, and preferably in the range of 2 <Cu≤2.5 in molar ratio with respect to other elements. As described above, the present inventors manufactured the CZTSe single target, unlike the conventional art, to form the light absorbing layer thin film material of the solar cell. In addition, the second phase is prevented from forming and With respect to the microstructure, etc., a composition capable of obtaining a desirable structure was found as described above. That is, the chemical composition of the CZTSe single target prepared according to the present invention may be represented by Cu _{(2 + a)} Zna + p) SnSe4, and the range of a is 0 <α <1, preferably 0 <a≤0.5. And the range of β is 0 <β≤1, preferably 0 <β≤0.5. That is, as described above, when a is 0, a second phase such as SnSe2 and SnSe is formed in a CZTSe thin film deposition to be formed later, and when a is 1, a second phase of CuSe is weakly formed, so that 0 <α It is preferable that it is <1, and especially when a is 0.5, since no second phase is formed in the thin film to be formed later, it is preferable that 0 <a≤0.5. In relation to Zn, when β is 0, many SnSe 2 and second SnSe phases are formed, and when β is 1, since such low 12 phases are not formed at all, the range of 0 <β ≤ 1 is good, and the stoichiometric atomic ratio From the standpoint of 0, the range of 0 <β≤ (λ5 is preferable. In particular, when α and β are both 0.5, as described below, the best results are obtained with respect to the efficiency of the solar cell. In the composition range, α and β may be 0 as long as a and β do not become zero at the same time, ie, in Fig. 3, Cu has a fixed molar ratio of 2 (ie a is 0). In addition, the Zn content is measured by changing the content of Zn, and the content of Zn is measured by changing the Cu content while fixing the content of Zn. Cu _{(2 + a)} Zna + i3) SnSe ₄ , and more precisely 0≤α <1 ᅳ 0≤β≤1 (where at least one of a and β is greater than 0), and the preferred ranges are 0≤α≤0.5, 0≤β≤0.5 (where a and at least one of β increase is greater than zero). On the other hand, the inventors formed a solar cell light absorbing layer using the CZTSe single target of the various compositions, to manufacture a solar cell ᅳ Specifically, after depositing a Mo layer, a lower electrode on the glass substrate by the sputtering method, the present invention After forming the CZTSe thin film (light absorbing layer) presented in the above, a CdS layer serving as a buffer layer to alleviate the band gap energy difference was deposited by the CBE Chemical bath deposition method. The intrinsic ZnO layer was deposited by a thin sputtering method to prevent energization with the upper electrode, and the Al-doped ZnO layer, which is the upper electrode, was deposited using the sputtering method. A1 (metal grid), a patterned metal electrode on top, was deposited by thermal evaporation to produce a solar cell having an active area of 0.2 cm ² (glass / Mo / CZTSe / CdS / iZnO / Al— ZnO / Al). The light absorbing layer was deposited using a single target of various compositions, and the CZTSe thin film formed using Cu ^ Z .sSnSe single target showed the best quality after annealing. Such as Cu ₂ . ₅ Zm. IV characteristics of the ₅ SnSe ₄ thin film solar cell were measured, and the results and related parameters are shown in FIG. 5. As shown in FIG. 5, an effect of about 4.16% was obtained, and Cu _2.5 Zni. _In the case of ₅ SnSe4 thin films, the grain size is large and the composition is optimized, which is considered to have high efficiency as described above. The maximum efficiency gained from CZTSe thin film solar cells formed by the simple sputtering method reported to date is about 3.2%. In this case, the target used was a metal target consisting of each element, and after depositing a metal precursor layer to form a CZTSe thin film through the selenization process. Even when comparing the effect obtained by the present invention with the conventional one, the effect of about 30% was improved. In addition, the present inventors examined whether the CZTSe single target including Ge can be prepared. That is, Ge is an element that increases the band gap energy, and exhibits desirable characteristics when included in thin film deposition. The CZTSe material has a bandgap energy of about 0.9 eV, which is lacking in visible light absorption that can yield the highest efficiency. According to one embodiment of the present invention, by forming a CZTSe single target containing Ge to form a thin film, it is possible to improve the bandgap energy to more than 1 eV through which the light absorption layer ideal for absorbing visible light can be manufactured In other words, it was possible to prepare a single target by including Ge in the same manner as described above, in which Ge was found to be substituted by Sn, and the CZTSe target containing Ge was Cu ₍₂₊ _a). Zn ₍ i _{+ P)} can be represented by the general formula of Sni- _x Ge _x Se 4 (0 <x <l). FIG. 6 shows a microscope (TEM) of a CZTGeSe thin film solar cell formed using a CZTSe target containing Ge in FIG. 6. ) Showed a photo. As shown, it can be seen that the CZTGeSe thin film is clearly formed. Meanwhile, the microstructure of the thin film according to the Ge content is shown in FIG. 7. As can be seen from Figure 7, it can be seen that as the content of Ge increases, the growth of grain is improved. In addition, it was confirmed that as the Ge content was increased, the intensity of the CZTSe (112) peak was reduced and shifted to a greater intensity (see FIG. 8). Only the shift of the (112) peak was observed without any other secondary phases, suggesting that Ge was a good substitute for Sn in the CZTSe material. In addition, the decrease in the intensity of the peak was observed in the CZTSe thin film containing a certain amount of Ge, a large amount of Ge seems to have an adverse effect on the improvement of crystallinity. In addition, the optical band gap energy calculated by the photon energy vs ahv curve was 0.93 eV (0 Ge) and 0.96 eV (0.3 Ge), respectively. That is, it was confirmed that the band gap energy of the thin film was increased by adding Ge. The inventors further studied the means to increase the band gap energy of the thin film. That is, similarly to Ge, S is an element that increases the band gap energy, and examined whether or not it exhibits desirable characteristics when included in the thin film. Specifically, after sputtering using the CZTSe target configured as described above to form a thin film, heat treatment with additional Se pellets (Se sample), sputtering using a CZTSe target to form a thin film, and then additional Se after the heat treatment with the pellets were heat-treated again in H _₂ S / N ₂ atmosphere (Se / S samples), and then by sputtering using a target CZTSe form a thin film to a heat treatment in the atmosphere _2. eu SN (H ₂ S sample). Various properties were measured for each sample, and the results are shown in FIG. 9.

As can be seen in the left figure of FIG. 9 showing the XRD pattern, all the Se of the samples were replaced with S through the sulfurization as described above, and no additional secondary phase was formed. On the other hand, as shown in the right figure, the band gap energy of the Se sample, the Se / H ₂ S sample, and the H ₂ S sample was 0.97 eV, 1.09 eV, and 1.20 eV, respectively. That is, it was confirmed that the band gap energy of the CZTSSe-based thin film could be increased by sulfur treatment. As mentioned above, although this invention was demonstrated with reference to the preferred embodiment, this invention is not limited to the said embodiment. The above embodiments can be variously modified and modified within the scope of the following claims, which are also within the scope of the present invention. Accordingly, the invention is limited only by the claims and the equivalents thereof.

Claims

[Claim 1] [Claim 1] A target manufacturing method for use in depositing a CZTSe (Cu—Zn ᅳ Sn—Se) based light absorbing layer thin film of a solar cell,

(1) preparing Cu, Zn, Sn and Se powders at a molar ratio of 2 + α: 1 + β: 1: 4,

(2) putting Cu, Zn, Sn, and Se powder and a metal ball into a container to stir to synthesize CZTSe material by mechanical force;

(3) pressurizing and sintering the synthesized CZTSe material to produce pellets shaped to target shapes;

(4) Step of preparing a ^■ Final CZTSe single target to a heat treatment for the pellets prepared above,

Wherein the final CZTSe single target comprises a composition of Cu _{(2 + a)} Zna _{+ (} 3) SnSe4 (0 <α <1, 0 <β <1, wherein at least one of _α and β is greater than 0). Target manufacturing method characterized by having.

[Claim 2]

The method of claim 1, wherein a and β are 0 <α <0.5 and 0 <β <0.5, provided that at least one of a and β is greater than 0.

[Claim 3]

The method of manufacturing a target according to claim 2, wherein a and β are both 0 and 5.

【Claim 4】 ^.

The method according to any one of claims 1 to 3, wherein the synthesis of the CZTSe material in the step (2) is carried out at room temperature and atmospheric pressure.

[Claim 5]

The method according to claim 4, wherein in the step (4), the heat treatment is performed at a degree of silver and atmospheric pressure of about 300 ^° C.

[Claim 6]

The method according to any one of claims 1 to 3, wherein the Ge powder in step (1) is further added in a molar ratio of Sn: Ge = l ᅳ x: x, and the steps of (2) to (4). Further comprising preparing a CZTGeSe single target, wherein the CZTGeSe single target has a composition of Cii ₍ 2 _{+ a)} Zna + Sni-xGexSe ^ CK1).

[Claim 7]

A single target for use in depositing a CZTSe (Cu-Zn-Sn-Se) based light absorbing layer thin film of a solar cell, wherein an additional single target is Cu (2 _{+ a)} Zn ₍₁₊ p) SnSe4 (0 <α < 1, 0 <β <1, provided that at least one of a and β is greater than 0).

[Claim 8]

8. The single target of claim 7, wherein α and β are 0 ≦ α ≦ 0.5 and 0 ≦ β ≦ 0.5, provided that at least one of α and β increases greater than zero.

[Claim 9]

The single target of claim 7, wherein the single target further comprises Ge, and the CZTSe single target including Ge has a composition of Cu + cZnii + i ^ Sni-xGexSeOK l).

[Claim 10]

Providing a glass substrate;

Forming a lower electrode on the glass substrate;

Forming a CZTSe (Cu-Zn-Sn-Se) -based light absorbing layer thin film on the lower electrode, forming a buffer layer on the light absorbing layer thin film to reduce a band gap energy difference;

Forming an upper electrode and a metal grid on the buffer layer

Including

The CZTSe based light absorbing thin film Cu ₍₂₊ a) Zn (i ₊ p) the composition of _{SnSe 4 (0 <α <1} , 0 <β <1. However, at least one of a and β is ^"greater than zero), Solar cell manufacturing method characterized by having.

[Claim 11]

The thin film of claim 10, wherein the light absorbing layer thin film is formed by sputtering a CZTSe single target having a composition of Cu + c Znd + SnSe (0 <α <1, 0 <β <1, wherein at least one of a and β is greater than 0). Forming a solar cell, characterized in that formed.

[Claim 12]

The method of claim 11, wherein the CZTSe single target is

(4) heat-treating the prepared pellets to produce a final CZTSe single target

Solar cell manufacturing method characterized in that is manufactured through.

[Claim 13]

The method of claim 10, wherein a and β are 0 ≦ α ≦ 0.5 and 0 ≦ β ≦ 0.5 (where at least one of a and β is greater than 0).

[Claim 14]

The method according to claim 12, wherein the synthesis of the CZTSe material in the step (2) is a solar cell manufacturing method, characterized in that carried out at the phase silver and atmospheric pressure.

[Claim 15]

The method according to claim 14, wherein in the step (4), the heat treatment is performed at a temperature of about 300 ^° C and a high pressure.

[Claim 16]

The method according to claim 14, wherein the Ge powder in the step of (1) is further prepared by adding a molar ratio of Sn: Ge = l—x: x, and the CZTGeSe single target is prepared through the steps of (2) to (4). Further comprising, wherein the single CZTGeSe target has a composition of Cu + c Zna + S -xGexSe ^ CKx ^). ·

[Claim 17]

The method according to any one of claims 10 to 16, wherein after forming the light absorbing layer thin film, heat treatment with additional Se pellets and then heat treatment in H ₂ S / N ₂ atmosphere or the light absorbing layer thin film is formed Thereafter, by heat treatment in an H ₂ S ₂ atmosphere, further comprising the step of including sulfur in the light absorbing layer thin film.

[Claim 18]

The method of claim 17, wherein the sulfur is included in the thin film by substituting Se of the light absorbing layer thin film after the heat treatment.

[Claim 19]

Substrate,

A lower electrode formed on the substrate;

A CZTSe (Cu-Zn-Sn—Se) -based light absorbing layer thin film formed on the upper and lower electrodes, a buffer layer formed on the light absorbing layer thin film to serve to alleviate the band gap energy difference,

An upper electrode and a metal grid sequentially formed on the buffer layer

Including

The CZTSe-based light absorbing layer thin film has a composition of Cu _{(2 + a)} Zn _{(1 + P)} SnSe4 (0 <α <1, 0 <β <1, wherein at least one of a and β is greater than 0). A solar cell characterized by the above-mentioned.

[Claim 20]

The thin film of claim 19, wherein the light absorbing layer thin film is formed by sputtering a CZTSe single target having a composition of Cuu + coZnd + SnSe (0 <α <1, 0 <β <1, wherein at least one of a and β is greater than 0). Solar cell characterized in that. .

[Claim 21] The solar cell according to claim 20, wherein α and β are 0 <α <0.5 and 0 <β <0.5 (where at least one of α and β is greater than 0).

[Claim 22]

The light absorbing layer thin film of claim 19, wherein the light absorbing layer thin film further comprises Ge, and the CZTSe light absorbing thin film containing Ge has a composition of Cuu + c Znn + i ^ Sm-xGexSe ^ l). Solar cell.

[Claim 23]

22. The solar cell of any one of claims 19 to 21, wherein the light absorbing layer thin film is further heat-treated in an H ₂ S / N ₂ atmosphere.