KR20210017480A - A method of controlling the size of crystal grains in the CZTSSe light absorbing layer - Google Patents

Abstract

In manufacturing a CZTSSe light absorption layer, provided is a method of adjusting the size of a crystal grain in a CZTSSe light absorption layer by adjusting the amount of Se being in contact with a Cu precursor, a Zn precursor, and a Sn precursor. According to the method of adjusting the size of the crystal grain in the CZTSSe light absorption layer provided in one aspect of the present invention, the crystal grain is formed with a large size at a low temperature, the efficiency of the CZTSSe light absorption layer is improved by appropriately adjusting the size of the crystal grain, and it is unnecessary to additionally supply a precursor source during an annealing process.

Description

A method of controlling the size of crystal grains in the CZTSSe light absorbing layer

It relates to a method of controlling the size of crystal grains in the CZTSSe light absorption layer.

Kesterite (Cu ₂ ZnSn(S _1-x Se _x ) ₄ , CZTSSe) solar cell, a solar technology that is harmless to the earth, is one of the most promising technologies. However, unlike CIGS, CZTSSe shows very low efficiency compared to theoretical efficiency. Although effective techniques for CIGS have been applied to CZTSSe, it is reported that the efficiency of CZTSSe is difficult to improve due to several factors such as small defect formation energy and the presence of secondary phases and voids. These problems make it difficult to manage the photogenerated carrier.

For efficient carrier management in the CZTSSe layer, a method may be devised to reduce the number of recombination sites by increasing the grain boundary or reducing the grain size. In general, control of grain boundaries is a major concern for polycrystalline thin film solar cells. The light absorbing layer composed of small grains degrades device performance due to vertical current flow through multiple grain boundaries. Current and voltage losses can be caused by non-radiative recombination of electrons and holes and scattering at grain boundaries. Therefore, various methods have been attempted to increase the grain size for carrier management.

In general, as the annealing temperature and time increase, the grain size increases. However, in this case, since CZTSSe is decomposed by Mo and the thickness of MoSSe increases, efficiency will decrease. Therefore, there is a need for a method of increasing the grain growth rate at a low temperature in a short time while suppressing the growth of MoSSe.

An object of the present invention is to provide a method of controlling the size of crystal grains in the CZTSSe light absorbing layer.

In order to achieve the above object, in one aspect of the present invention

In preparing the CZTSSe light absorption layer,

A method of controlling the size of crystal grains in the CZTSSe light absorption layer by controlling the amount of Se in contact with the Cu precursor, the Zn precursor, and the Sn precursor is provided.

In addition, in another aspect of the present invention

There is provided a method for manufacturing a CZTSSe light absorbing layer including a sulfidation-selenization step using a method of adjusting the size of crystal grains in the CZTSSe light absorbing layer.

In addition, in another aspect of the present invention

A CZTSSe light absorbing layer manufactured by the above manufacturing method is provided.

Furthermore, in another aspect of the present invention

A solar cell including the light absorption layer is provided.

The method of controlling the size of crystal grains in the CZTSSe light absorption layer provided in one aspect of the present invention has the effect of increasing the size of the crystal grains at low temperature, and improves the efficiency of the CZTSSe light absorption layer by appropriately adjusting the size of the crystal grains. There is an effect that can be achieved, and there is an advantage that there is no need to additionally supply a precursor source during an annealing process.

1 shows a FESEM image of a CZTSSe light absorbing layer according to an embodiment of the present invention. FIG. 1A shows a surface, FIG. 1B shows a cross section, and FIG. 1C shows an enlarged view of the cross section.
2 is a diagram showing an FESEM image and a schematic diagram in an annealing process of a CZTSSe light absorbing layer according to an embodiment of the present invention,
2a, 2b, and 2c are schematic diagrams showing the FESEM image of the surface, the FESEM image of the cross section, and the Cu-Sn alloy distribution at 400°C, respectively,
2d, 2e, and 2f are schematic diagrams showing the FESEM image of the surface, the FESEM image of the cross section, and grain size distribution at 480°C, respectively,
2G and 2H show FESEM images before and after etching after the sulfidation-selenization process is completed, respectively.
FIG. 3A is a schematic diagram showing annealing conditions in an annealing process of a CZTSSe light absorbing layer according to an embodiment of the present invention, FIG. 3B is a central part, FIG. 3C is an intermediate position, and FIG. 3D is an FESEM image at an edge.
4 is a schematic diagram showing the growth of liquid-assisted crystal grains in the CZTSSe light absorbing layer according to an embodiment of the present invention,
4A to 4B are schematic diagrams showing the dissolution and growth of crystal grains, and FIGS. 4C to 4E are schematic diagrams showing the final microstructure according to the fraction of L-CTSSe,
4F is a schematic diagram showing the shape of crystal grains under liquid conditions,
Figure 4g is a schematic diagram showing the nucleation of crystal grains,
4H is a graph showing the grain growth rate according to the reaction control.
5 shows an FESEM image of a CZTSSe light absorbing layer in a Zn-poor condition according to an embodiment of the present invention, and FIGS. 5A and 5B show images showing a surface and a cross section, respectively.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by an expert skilled in the art to which the present invention belongs. In general, the nomenclature used in this specification is well known and commonly used in the art.

In one aspect of the present invention

In preparing the CZTSSe light absorption layer,

A method of controlling the size of crystal grains in the CZTSSe light absorption layer by controlling the amount of Se in contact with the Cu precursor, the Zn precursor, and the Sn precursor is provided.

Hereinafter, a method of controlling the size of crystal grains in the CZTSSe light absorbing layer provided in one aspect of the present invention will be described in detail.

The method of controlling the size of crystal grains in the CZTSSe light absorbing layer provided in an aspect of the present invention is performed by adjusting the amount of Se.

Specifically, as the amount of Se increases, the size of the crystal grains may increase, and when the amount of Se is small, the size of the crystal grains may decrease.

The method of controlling the size of the crystal grains in the CZTSSe light absorbing layer may be achieved by adjusting the fraction of the liquid phase in the CZTSSe light absorbing layer.

The liquid phase may be one or more liquid phases selected from the group consisting of Cu-Sn-Se and Cu-Sn-SSe.

Specifically, as the amount of Se increases, the amount of the Cu-Sn-Se or Cu-Sn-SSe liquid phase may increase, and as a result, the size of the crystal grains may increase through liquid-assisted growth.

Control of the amount of Se may be performed by adjusting the content of Se in the precursor, the amount and direction of supply of Se in the sulfidation-selenization process, and the arrangement of Se.

The method of controlling the size of crystal grains in the CZTSSe light absorbing layer provided in an aspect of the present invention is performed by contacting Se with a Cu precursor, a Zn precursor, and a Sn precursor.

The Cu precursor, Zn precursor and Sn precursor may be pure metal or metal sulfide.

The Se may be supplied in a solid or gaseous form.

The Cu precursor, Zn precursor, and Sn precursor may be disposed in the order of Cu/Sn/Zn/substrate or Sn/Cu/Zn/substrate.

The method of controlling the size of crystal grains in the CZTSSe light absorbing layer provided in one aspect of the present invention may be performed by further adjusting the content of Zn.

Specifically, when the content of Zn is small, the amount of the Cu-Sn-Se or Cu-Sn-SSe liquid phase may increase, and as a result, the size of the crystal grains may increase through liquid-assisted growth.

Control of the content of Zn may control the amount of Zn in the precursor, the amount of volatilization according to temperature, and the arrangement of Zn.

The method for controlling the size of crystal grains in the CZTSSe light absorption layer provided in one aspect of the present invention is, specifically, a principle of forming a liquid Cu-Sn-Se or Cu-Sn-SSe, thereby causing a liquid auxiliary crystal grain growth therefrom. .

Such a liquid phase is involved in grain growth in the entire area within the light absorption layer.

The more Se-rich, the more Cu-poor, the more this liquid is formed.

When the liquid phase is formed, since it is advantageous for material movement, very large crystal grains can be formed, and as a result, the efficiency of the light absorbing layer can be improved.

According to the method of controlling the size of the crystal grains in the CZTSSe light absorbing layer provided in one aspect of the present invention, the average size of the crystal grains of CZTSSe may be 2 µm or more, specifically, 3 µm to 10 µm, and more specifically It may be 4 μm to 8 μm.

Further, since such a process can be performed at a relatively low temperature, the problem of forming a secondary phase on the surface by controlling the decomposition of CZTSSe and the problem of increasing the thickness of MoSSe can be solved.

Furthermore, there is an advantage that there is no need to supply an SnS source during an annealing process to prevent decomposition of CZTSSe.

The Cu-Sn-Se or Cu-Sn-SSe liquid phase is preferably formed so that the CZTSSe crystal grains are sufficiently liquid-assisted to grow, but finally the Cu-Sn-Se or Cu-Sn-SSe liquid phase remains at the grain boundaries of CZTSSe. It is desirable to adjust so as not to.

That is, the Cu-Sn-Se or Cu-Sn-SSe liquid phase can improve the performance of the light absorbing layer by increasing the size of the crystal grains. However, if the liquid phase is formed excessively and finally the liquid phase remains at the grain boundaries of CZTSSe, It is possible to reduce the performance of the absorbing layer.

In another aspect of the present invention

There is provided a method for manufacturing a CZTSSe light absorbing layer including a sulfidation-selenization step using a method of adjusting the size of crystal grains in the CZTSSe light absorbing layer.

Hereinafter, a method of manufacturing a CZTSSe light absorbing layer provided in another aspect of the present invention will be described in detail.

First, a method of manufacturing a CZTSSe light absorption layer provided in another aspect of the present invention may include forming a precursor layer on a substrate.

The substrate may be a hard substrate or a flexible substrate. For example, when a hard material substrate is used as the substrate, a glass plate, a quartz plate, a silicon plate, a synthetic resin plate, a metal plate, or the like may be included. Preferably, a transparent insulating material may be used as the substrate, and specifically, soda lime glass, borosilicate glass, and alkali free glass substrates are also included therein.

Alternatively, in the case of using a substrate made of a flexible material, at least one of a metal or a polymer material may be included, for example, among molybdenum foil, titanium foil, stainless steel (SUS), or polyimide It may include at least one.

Before forming the precursor layer on the substrate, a first electrode may be formed.

The first electrode is molybdenum (Mo), copper (Cu), aluminum (Al), nickel (Ni), tungsten (W), cobalt (Co), titanium (Ti), copper (Cu), gold (Au), or It may include at least one of these alloys. In this case, preferably, the rear electrode may be a molybdenum (Mo) electrode. Molybdenum (Mo) is capable of high electrical conductivity and ohmic bonding with a CZTS-based light absorbing layer, and has excellent heat resistance and interfacial adhesion. The thickness of the back electrode may be 02 μm to 5 μm, and may be formed by a sputtering process.

The precursor layer may include copper (Cu), zinc (Zn), and tin (Sn).

The precursor layer may be formed by at least one of an individual element lamination method or a simultaneous deposition method. The individual element lamination method is a method of sequentially laminating layers containing only one element.

The metal precursor may be stacked in the order of Cu/Sn/Zn/first electrode or Sn/Cu/Zn/first electrode on the first electrode in consideration of the composition ratio and uniformity after heat treatment. It is not particularly limited. The precursor layer may be formed by sputtering, chemical vapor deposition (CVD), organic metal chemical vapor deposition (MOCVD), close-spaced sublimation (CSS), spray pyrolysis, and Chemical spraying (Chemical spraying), screen printing (Screeen printing), non-vacuum liquid film formation method, CBD method (Chemical bath deposition), VTD method (Vapor transport deposition), and any one of the electrodeposition (electrodeposition) method Can be formed by

The co-sputtering is a vacuum-based simultaneous deposition method. Copper (Cu), zinc (Zn), and tin (Sn) are simultaneously deposited on the first electrode to form copper (Cu) and zinc (Zn) having a set composition. ) And a precursor layer including tin (Sn) may be formed.

Next, the method of manufacturing the CZTSSe light absorption layer provided in another aspect of the present invention may include the step of sulfiding-selenizing the precursor layer.

The sulfurization-selenization step may be performed by supplying at least one of a gas and an inert gas including at least one of S ₂ , Se ₂ , H ₂ S or H ₂ Se.

Material in which the gas comprises S _2, Se _2, H ₂ may be supplied, including at least one material selected from the group consisting of S or H ₂ Se, or S _2, Se _2, H at least one of the ₂ S or H ₂ Se It may be supplied by mixing and inert gas. The _{S 2, Se 2, H 2} S or H ₂ Se in the mixture if one or more of the at least one gas and an inert gas is mixed supply _{S 2, Se 2, H 2} S or H ₂ Se, at least one gas of The volume ratio of and the inert gas may be 0.01:1 to 1:1. The gas may control the chalcogenization of the precursor layer during the subsequent sulfidation-selenization process, and suppress elemental loss of the precursor. A method of supplying gas into the chamber may be supplied through a quartz tube connected to the chamber.

The sulfidation-selenization step may include heating sulfur or selenium disposed in the chamber to sulfide or selenize the precursor layer.

The sulfur or selenium disposed in the chamber may preferably be in a solid form, and if a gas containing sulfur (S) is supplied in the step of supplying the gas into the chamber, selenium (Se) is preferably disposed in the chamber. If gas containing chalcogen including selenium (Se) is supplied into the chamber, sulfur (S) may preferably be disposed in the chamber.

The step may be carried out at a temperature of 250 ℃ to 500 ℃. Preferably it can be carried out at a temperature of 300 ℃ to 480 ℃. When performed at a temperature of less than 250°C, there is a problem that the light absorbing layer is not sufficiently sulfided-selenized. When performed at a temperature exceeding 500°C, CZTSSe is decomposed by Mo and the thickness of MoSSe increases. There is a problem that the efficiency of the absorption layer may decrease.

The method of manufacturing the CZTSSe light absorbing layer provided in another aspect of the present invention is preferable in that it is possible to grow crystal grains at low temperatures by controlling the fraction of the liquid phase by controlling the amount of Se.

In the method for manufacturing a CZTSSe light absorption layer provided in another aspect of the present invention, the average size of the crystal grains of CZTSSe after the sulfidation-selenization process may be 2 μm or more, specifically 3 μm to 10 μm, and more specifically 4 It may be ㎛ to 8 ㎛.

In the above step, the Cu-Sn-Se or Cu-Sn-SSe liquid phase is preferably formed so that the CZTSSe crystal grains are sufficiently grown in the liquid phase, but finally the Cu-Sn-Se or Cu-Sn-SSe liquid phase after the above step is It is preferable to control so that it does not remain in the grain boundaries of CZTSSe.

That is, the Cu-Sn-Se or Cu-Sn-SSe liquid phase can improve the performance of the light absorbing layer by increasing the size of the crystal grains. However, if the liquid phase is formed excessively and finally the liquid phase remains at the grain boundaries of CZTSSe, It is possible to reduce the performance of the absorbing layer.

In another aspect of the present invention

A CZTSSe light absorbing layer manufactured by the method of manufacturing the light absorbing layer is provided.

In another aspect of the present invention, a solar cell including the light absorbing layer is provided.

In the light absorbing layer and solar cell provided in another aspect and another aspect of the present invention, the method for adjusting the size of crystal grains in the CZTSSe light absorbing layer and the method for manufacturing the CZTSSe light absorbing layer described above can be applied, and will be described in duplicate. I don't.

Hereinafter, the present invention will be described in more detail through examples and experimental examples. The scope of the present invention is not limited to specific embodiments, and should be interpreted by the appended claims. In addition, those who have acquired ordinary knowledge in this technical field should understand that many modifications and variations can be made without departing from the scope of the present invention.

<Example 1> Preparation of CZTSSe light absorption layer

600 nm thick Mo layer, 1.8 μm thick CZTSSe light absorbing layer, 50 nm thick CdS buffer layer, 50 nm thick pure ZnO layer, 300 nm thick Al-doped ZnO (AZO) layer on a soda lime glass (SLG) substrate, A 10 nm thick Ni and 2 μm thick Al grid, and a 100 nm thick MgF ₂ layer were formed.

The Mo layer was deposited on the SLG substrate through DC magnetron sputtering using a Mo target of 99.99% purity.

The light-absorbing layer uses 99.99% pure Sn, Cu, and Zn sputtering targets in the stacking order of Sn (275 nm) / Cu (160 nm) / Zn (188 nm) / Mo to deposit the metal precursor for the CZTSSe light-absorbing layer on the Mo layer. Deposited. For the sulfidation-selenization process, all samples were placed in a sample box consisting of a Se boat made of quartz, a sample holder made of SiC coated graphite and a quartz cover plate. Before the annealing began, solid Se (about 250 mg), H ₂ S (diluted with 90 vol% Ar, 250 sccm, about 8 minutes) and Ar gas (2000 sccm, about 8 minutes) were supplied to the RTP chamber. To prevent decomposition of CZTSSe, the annealing process was performed in the RTP chamber at a pressure slightly lower than 1 atmosphere. The sample was heated from room temperature to 300° C. for 560 seconds and then held at 300° C. for 900 seconds. The sample was then heated from 300° C. to 480° C. for 1800 seconds and then held at 480° C. for 600 seconds.

The CdS buffer layer is formed by chemical solution deposition, the pure ZnO layer and the Al-doped ZnO (AZO) layer are formed through sputtering, and the Ni and Al grid and MgF ₂ layer are formed through electron beam evaporation.

<Example 2> Preparation of light absorption layer with reduced Zn content

It was prepared in the same manner as in Example 1, but a light absorbing layer was prepared from a precursor whose Zn content was reduced by 75% compared to Example 1.

<Experimental Example 1>

For Example 1, morphology analysis was performed through FESEM.

As can be seen in FIG. 1A, the size distribution of the grains is bimodal, and grains having a size of 5 μm or more are easily found.

In general, it is difficult to form such large grains below 500°C. For example, when selenization is performed at 550°C for 30 minutes, it is reported that the CZTSe particle size of about 2 μm is formed almost uniformly.

In addition, when CZTSSe grains are selenized at 500° C. for 10 minutes, it is reported that grains of about 1 μm are uniformly formed.

That is, in the case of Example 1, it can be seen that even though the heat treatment was performed at a relatively low temperature of 480°C, the grain size was remarkably increased.

In addition, a liquid phase is observed at the grain boundary of CZTSSe as can be seen in FIG. 1B. The observed liquid phase is predicted to be a Cu-Sn-SSe liquid phase.

2A shows the observed voids and distribution of Cu-Sn alloys in samples annealed at 400°C. In the case of using a pure metal precursor (Sn/Cu/Zn/Mo), an alloy state is formed as shown in Reaction Formula 1 below at a temperature of room temperature to 300°C during the sulfidation-selenization process.

Zn + Sn + Cu → Cu-Sn alloy + Cu-Zn alloy + Sn (Scheme 1)

Thereafter, ZnSSe is formed as shown in Scheme 2 below by a de-zinc reaction and a first reaction at a temperature between 300°C and 400°C.

Cu-Sn alloy + Cu-Zn alloy + S + Se → ZnSSe + Cu-Sn alloy (Scheme 2)

Thereafter, a CTSSe phase is formed at a temperature between 400°C and 440°C (Scheme 3), and a CZTSSe phase is formed at a temperature between 440°C and 480°C.

Cu-Sn alloy + S + Se → CuSSe + SnSSe → CTSSe (Scheme 3)

CTSSe + ZnSSe → CZTSSe (Scheme 4)

In the step corresponding to Scheme 2, as can be seen in FIG. 2A, the voids under the ZnSSe layer and the Cu-Sn alloy are aggregated.

Aggregation of these and Cu-Sn alloys causes local composition differences. Accordingly, Zn-rich and Zn-poor regions may be formed as can be seen in FIGS. 2B and 2C.

The area where the void exists under the ZnSSe layer will be the Zn-rich area, and the area where the Cu-Sn alloy exists under the ZnSSe layer will be the Zn-poor (Cu-Sn rich) area.

Under conditions rich in chalcogen elements, the CZTSSe phase is formed through Equations 3 and 4. Cu and Sn pass through the ZnSSe layer to form Cu-SSe and Sn-SSe phases on the ZnSSe layer, and finally to form Cu-Sn-SSe phases. During this process, Zn-rich and Zn-poor (Cu-Sn rich) regions are formed by the occurrence of composition unevenness during the sulfidation-selenization process according to the pore distribution as described above, of which Zn-poor (Cu-Sn In the rich) region, the CTSSe phase is formed locally. Further, according to the Cu ₂ SnSe ₃ -Se phase diagram, liquid CTSSe (L-CTSSe) is formed under Se-rich conditions of 220°C or higher.

Accordingly, the liquid L-CTSSe remaining at the grain boundary is observed as shown in FIG. 1B.

2G shows the pore distribution of CZTSSe etched in the FESEM image, and FIG. 2H shows the grain size distribution of the CZTSSe surface before etching. Large pores are reported to occur due to preferential reaction of Zn and S/Se and aggregation of Cu-Sn, while small pores are reported to be formed by upward mass transfer of Cu and Sn under the ZnSSe layer.

That is, the large void region is a Zn-rich region, and the small void region is a Zn-poor (Cu-Sn rich) region. As can be seen in Figure 2e, CZTSSe exists on both sides of ZnSSe and can be divided into upper CZTSSe and lower CZTSSe.

As can be seen in FIGS. 2G and 2H, when a large pore is located under the upper CZTSSe, the crystal grain size of the upper CZTSSe is relatively small, and when a small pore is located under the upper CZTSSe, the crystal grain size of the upper CZTSSe is relatively Big.

That is, in the Se-rich condition, L-CTSSe may occur due to non-uniformity in composition, which may help the growth of crystal grains.

<Experimental Example 2>

The morphology of Example 2 was analyzed by FESEM, and is shown in FIG. 5.

As can be seen in FIG. 5, when the Zn on the precursor is decreased, more L-CTSSe is formed and the crystal size is larger than that of Example 1.

<Experimental Example 3>

For Example 1, the Se concentration flux and temperature gradient during the sulfidation-selenization process are shown in FIG. 3A. Since the sample edge of Example 1 is in contact with graphite, the temperature is relatively high, and the amount of volatilization of Zn is relatively large. Therefore, the edge becomes a Zn-poor or Cu-Sn-rich region.

Also, since Se vapor flows from edge to center, the edge position is always exposed to Se. That is, the edge corresponds to the Se-rich area.

It is difficult to find L-CTSSe in the center of the sample (Fig. 3B). In the case of the intermediate position, L-CTSSe begins to be found at the grain boundaries (Fig. 3c).

The edge of the sample is Zn-poor, and L-CTSSe appears as a Se-rich region (Fig. 3D). In addition, it can be seen that almost all of the voids disappear due to the relocation effect of the liquid phase.

That is, the microstructure in which L-CTSSe surrounds CZTSSe grains may occur in many Zn-poor and Se-rich regions.

Fig. 4 shows a liquid-assisted crystal grain growth mechanism that can occur when a liquid is present. 4A to 4E show schematic diagrams of liquid-assisted grain growth. In the grain growth stage, when L-CTSSe coexists with CZTSSe grains, mass transfer that increases the CZTSSe grain size can easily occur through the liquid phase, so the growth rate of CZTSSe grains may increase even in a low-temperature process. If the amount of L-CTSSe is small, the L-CTSSe residue can be removed by sufficient reaction with ZnSSe as shown in FIG. 4C, and if the amount of L-CTSSe is large, the residue remains at the grain boundaries, and the grains are rearranged. Accordingly, the void may disappear (Fig. 3D)

4F shows the CZTSSe facet grain shape at the center and edge of the sample due to abnormal liquid-assisted grain growth.

In the case of abnormal grain growth, as shown in Figs. 4G and 4H, specific facets appearing through reaction control are observed. In general, a planar facet has a low surface energy due to a low dangling bond density, and a critical radius for stable nucleation is larger than a surface having a large surface energy. When the newly formed nucleus is smaller than the critical radius, the nucleus disappears because it is unstable, and when the nucleus is larger than the critical radius, it stabilizes and contributes to growth.

In the direction A of FIG. 4F, the initial grain growth rate is relatively high due to the relatively large surface energy. Therefore, grain growth can easily occur due to a small critical radius (r ^* _A ) for nucleation.

On the other hand, since the surface B of FIG. 4F has a small surface energy and thus has a large critical radius (r ^* _B ) for stable nucleation, formation of nuclei is not easy. However, after stable nucleation is formed on the B facet, it corresponds to the reaction-controlled grain growth in FIG. 4G, so that the rate of grain growth along the facet is very fast due to rapid charging at the kink site and the step site.

Claims (11)

In preparing the CZTSSe light absorption layer,
A method of controlling the size of crystal grains in the CZTSSe light absorption layer by controlling the amount of Se in contact with the Cu precursor, the Zn precursor, and the Sn precursor.
The method of claim 1,
The method of controlling the size of the crystal grains in the CZTSSe light absorption layer, characterized in that the control of the size of the crystal grains is achieved by adjusting the fraction of the liquid phase in the CZTSSe light absorption layer.
The method of claim 2,
The liquid phase is at least one liquid phase selected from the group consisting of Cu-Sn-Se and Cu-Sn-SSe. Method for controlling the size of crystal grains in the CZTSSe light absorption layer.
The method of claim 1,
The Cu precursor, the Zn precursor, and the Sn precursor are pure metals or metal sulfides, wherein the size of crystal grains in the CZTSSe light absorption layer is controlled.
The method of claim 1,
The method of controlling the size of crystal grains in the CZTSSe light absorption layer, characterized in that the Se is supplied in a solid or gaseous form.
The method of claim 1,
The Cu precursor, the Zn precursor, and the Sn precursor are arranged in the order of Cu/Sn/Zn/substrate or Sn/Cu/Zn/substrate. The method of controlling the size of crystal grains in the CZTSSe light absorption layer.
The method of claim 1,
A method of controlling the size of crystal grains in the CZTSSe light absorbing layer, wherein the content of Zn in the light absorbing layer is further controlled.
A method of manufacturing a CZTSSe light absorbing layer comprising a sulfidation-selenization step using the method of controlling the size of crystal grains in the CZTSSe light absorbing layer of claim 1.
The method of claim 8,
The sulfidation-selenization step is a CZTSSe light absorption layer manufacturing method, characterized in that carried out at a temperature of 250 ℃ to 500 ℃.
The CZTSSe light absorption layer manufactured by the manufacturing method of claim 8.
A solar cell comprising the light absorption layer of claim 10.

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