KR20190000339A - Thin-Film Solar Cell Module Structure and Method for Producing the Same - Google Patents

Abstract

Provided is a thin-film solar cell module structure in which photoelectric conversion efficiency, productivity, and functionality are improved. The thin-film solar cell module structure includes: a transparent substrate; a first rear electrode stacked on the transparent substrate and having transparency; a second rear electrode stacked on the first rear electrode and including a metal nitride layer; a light absorption layer stacked on the second rear electrode and including metal chalcogenide; and a transparent electrode stacked on the light absorption layer, wherein at least a portion of a first stack structure including the first rear electrode and the second rear electrode is separated in a first direction perpendicular to a stacking direction of the first stack structure, at least a portion of a second stack structure including the second rear electrode and the light absorption layer is separated in the first direction, and at least a portion of a third stack structure including the second rear electrode, the light absorption layer, and the transparent electrode is separated in the first direction.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a thin film solar cell module,

 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film solar cell module structure and a manufacturing method thereof, and more particularly, to a thin film solar cell module structure for improving the performance of a thin film solar cell by applying a substrate- And a module structure.

The present invention is a research project carried out with the support of MOTIE and Korea Institute of Energy & Evaluation (KETEP) (project assignment number: 20153030013060).

The applications of photovoltaic modules include not only conventional solar power plants for large-scale electricity production, but also building-integrated photovoltaic modules (BIPV) using urban buildings, VIPVs for transportation such as automobiles and buses, , And electronic devices (DIPV) that require portability. Among them, the building integrated solar module (BIPV) is divided into the method applied to the roof, the wall, and the window of the building. The window type solar module applied to the building window requires a certain amount of light transmission for mining.

The amorphous thin film Si solar cell secures translucency by removing the light absorbing layer by laser scribing, and the crystalline Si wafer solar cell is responding to the market demand by securing the translucency by using a gap where the cell is not applied.

However, the amorphous thin-film Si solar cell has a very low base efficiency of 11% and a very low conversion efficiency of less than 5% considering the additional losses associated with cell-to-module (CTM) Therefore, it is difficult to expect substantial photovoltaic output. In addition, since the crystalline Si cell can not impart its own light-transmitting property, it is difficult to use it as a light-emitting window due to the nature of the building design, which is very important for aesthetics. Further, such a light projecting type solar module is required to perform various functions (color modulation, etc.) of lighting for the inhabitants of the room, so that it is required to add a function that can take an esthetic part into consideration.

Cu (In _1-x , Ga _x ) (Se, S) ₂ (CIGS) and Cu ₂ ZnSn (Se, S) ₄ (CZTS), etc. Se and S thin film solar cells are formed by depositing molybdenum (Mo) as a back electrode on a glass substrate or a metal substrate and a polymer substrate, and then forming a CIGS thin film (or CZTS thin film) And a CdS thin film (or ZnS, In ₂ S ₃ ), intrinsic ZnO (or ZnMgO) and a transparent conductive oxide (TCO) electrode are sequentially deposited as an n-type window layer. Such CIGS or CZTS solar cells can be reduced in production cost by thinning compared with conventional silicon solar cells and can achieve a photoelectric conversion efficiency as high as 20% or more, which is considered as a strong candidate for the next generation solar cell market.

FIG. 1 shows a single integrated module structure of a CIGS light absorbing layer-based thin film solar cell using a conventional Mo back electrode. One of the advantages of manufacturing the module of the thin film solar cell is that it is possible to monolithic integration with the structure as shown in FIG. The thin film solar cell module separates each unit cell through the first patterning (P1) of the Mo back electrode, the second patterning (P2) after the CIGS / CdS / i-ZnO deposition and the third patterning (P3) ), And the adjacent cells are serially connected through the TCO / Mo connection of the second patterning (P2) region. FIG. 1 shows a structure in which three cells are connected in series as a part of the structure of the entire module. The single integrated solar module is constructed by repeating the structure of FIG. 1 in a serial connection manner.

FIG. 2 schematically shows a manufacturing process for forming a conventional CIGS thin film solar cell module structure. First, a molybdenum (Mo) rear electrode is deposited on a substrate and electrically insulated through a first patterning (P1) using a laser scriber. A light absorption layer, a CdS buffer layer, and an i-ZnO layer are deposited thereon, and then a rear electrode surface is exposed through a second patterning (P2) using a mechanical scriber. After the transparent electrode layer is deposited, the adjacent cells are electrically insulated through the third patterning (P3) using a mechanical processor. At this time, in the second patterning (P2) region, the upper electrode TCO layer and the rear electrode Mo contact each other to complete the series connection between adjacent cells.

In the case of machining used in the second patterning (P2) and the third patterning (P3), the equipment cost is somewhat less than the laser scriber. However, except for this point, productivity problems such as increase of defective rate occur due to the change of scribing width and quality due to abrasion of the machining tip during manufacturing of the module, and frequent tip replacement for solving this problem is a manufacturing process unit . In addition, since patterning by machining is very difficult to reduce the line width to a certain level or less, the power generation amount of the module is reduced by increasing the photovoltaic incapable area (the "dead zone" portion in FIG.

In order to solve this problem, it is necessary to develop a technique for applying a laser scriber to the second patterning (P2) and the third patterning (P3). Unlike the first patterning (P1) in which the thin film surface incidence method is possible, the second patterning (P2) and the third patterning (P3) make the laser incident from the transparent window layer, In order to reduce the damage, heat transfer must be suppressed by Mo back electrode by laser heating. For this, there arises a problem that an expensive laser such as a tens of picosecond (ps) pulsed laser or a femtosecond (fs) pulse laser should be applied.

Also, the reaction product of the Mo surface, which may occur during the removal of the CIGS thin film by laser heating, increases the TCO / Mo interface resistance of the second patterning (P2) region, thereby increasing the series resistance of the module. In addition, debris or the like generated during the scribing process causes shunting between cells or causes nonuniform characteristics in the subsequent thin film deposition.

As one of the methods for solving the above problems, Japanese Laid-Open Patent Publication No. 10- 2016-0050929 discloses a technique in which a substrate incident laser is applied to a substrate / TCO / Mo / CIGS / CdS / TCO laminated structure P1, P2, P3 processing technology and thin film solar module structure. However, the technique proposed in the above-mentioned patent publication tends to damage the TCO rear electrode during the peeling of the CIGS light absorbing layer through laser heating on the TCO / Mo or TCO / CIGS interface, so that P2 and P3 It is difficult to realize a small line width of 50 탆 or less in processing. If the TCO backside electrode is damaged, the series resistance of the photovoltaic module is increased, thereby deteriorating the photovoltaic efficiency. Therefore, there is a need for a cell structure technique or a laser processing technique for securing excellent laser processing performance so as to realize a smaller line width and minimize damage to the rear electrode.

In order to separate the CIGS light absorbing layer and the subsequent thin film (processing P2 and P3) through the laser processing of the substrate rear face incidence system as described above, the rear electrode adjacent to the substrate is transparent to the laser light so that the rear electrode / CIGS interface To be capable of direct heating. However, in the conventional rear electrode structure in which the Mo back electrode is located adjacent to the substrate, Mo damage can not be avoided when the laser is applied to the back surface of the substrate. Therefore, It is difficult to apply.

In addition, when the TCO is disposed adjacent to the substrate and used as a back electrode, diffusion of impurities (Na, K) from the substrate and diffusion of impurities (In, Sn, O) from the TCO in the high temperature deposition process for forming a CIGS light absorption layer The characteristics of the CIGS light absorbing layer may be deteriorated. In order to prevent this, introduction of a functional layer capable of preventing impurity diffusion without deterioration of electrode performance is required on the TCO rear electrode.

US 2013-0168797 A1 US 2013-0014800 A1 Korean Patent Publication No. 10-2016-0050929

 T. Nakada, "Microstructural and diffusion properties of CIGS thin film solar cells fabricated using transparent conducting oxide back contacts", Thin solid films, v.480-481 (2005) p.419-425   H. Simchi, et al., &Quot; Structure and interface chemistry of MoO3 back contacts in CIGS thin film solar cells ", J. Appl. Phys., V. 115 (2014) p. 033514   C. W Jeon, et al., "Controlled Formation of MoSe2 by MoNx thin film as a diffusion barrier against Se during selenization annealing for CIGS solar cell", Journal of Alloys and Compounds, v.644 (2015) p.317

Accordingly, it is an object of the present invention to provide a module structure of a thin film solar cell having improved photoelectric conversion efficiency, productivity, and functionality.

Another object of the present invention is to provide a thin film solar cell module capable of improving the patterning performance and quality of a light absorbing layer of a substrate incident laser system and improving the price, productivity and precision of a scribing process, And to provide a method of manufacturing the structure.

A module structure of a thin film solar cell according to an aspect of the present invention includes:

A transparent substrate;

A first rear electrode stacked on the transparent substrate and having transparency;

A second rear electrode stacked on the first rear electrode, the second rear electrode including a metal nitride layer;

A light absorbing layer stacked on the second rear electrode and including a metal chalcogenide; And

And a transparent electrode laminated on the light absorption layer,

At least a part of the first lamination structure including the first back electrode and the second back electrode is separated in a first direction perpendicular to the lamination direction of the first lamination structure,

At least a part of the second laminated structure including the second rear electrode and the light absorbing layer is divided in the first direction,

At least a part of the third laminated structure including the second rear electrode, the light absorbing layer and the transparent electrode is separated in the first direction.

In one embodiment, the modular structure of the thin film solar cell further comprises an auxiliary layer disposed between the photoabsorption layer and the transparent electrode, wherein the second lamination structure comprises the second back electrode, the light absorbing layer, And the third laminated structure may include the second rear electrode, the light absorbing layer, the auxiliary layer, and the transparent electrode.

In one embodiment, the auxiliary layer may comprise at least one of a buffer layer or a high-resistance window layer.

In one embodiment, the first back electrode and the transparent electrode may be connected in series at the separated portion of the second lamination structure.

In one embodiment, the first back electrode may include a material having a light absorption of 20% or less and a resistivity of 1 x 10 < ^-2 & gt ^; OMEGA .cm or less in the visible light or near infrared ray band.

In one embodiment, the first rear electrode comprises a transparent conducting oxide (TCO) comprising at least one selected from the group consisting of an oxide of indium (In), an oxide of zinc (Zn), and an oxide of tin (Sn) A nanowire layer and a TCO, and a transparent electrode in which a carbon material containing at least one of graphene and carbon nanotube is dispersed.

In one embodiment, the metal nitride layer may comprise a metal nitride represented by the following Formula 1:

≪ Formula 1 >

M _x (C _y N _1-y ) _{1 -x}

In Formula 1, 0.4? X? 0.9, 0? Y? 0.1,

M is at least one selected from tungsten (W), molybdenum (Mo), tantalum (Ta) and titanium (Ti).

In one embodiment, the thickness of the first back electrode is between 100 and 2000 nm, and the thickness of the second back electrode is between 1 and 200 nm.

In one embodiment, the modular structure of the thin film solar cell may further comprise an interfacial adhesion layer disposed between the first and second backside electrodes.

In one embodiment, the interfacial adhesion layer may comprise at least one selected from Mo, W, Ta, chromium (Cr), nickel (Ni) and Ti.

In one embodiment, the thickness of the interfacial adhesion layer may be between 1 and 50 nm.

In one embodiment, the modular structure of the thin film solar cell may further comprise an ohmic contact layer disposed between the second back electrode and the light absorbing layer.

In one embodiment, the ohmic contact layer may comprise at least one selected from Mo, gold (Au), an oxide of Mo, an oxide of W, an oxide of Ni, ITO, and FTO.

In one embodiment, the thickness of the ohmic contact layer may be between 1 and 50 nm.

In one embodiment, the light absorbing layer is selected from one or more selected from among copper (Cu) or silver (Ag), indium (In), gallium (Ga), aluminum (Al), zinc (Zn), and tin One or more selected from the group consisting of selenium (Se) and sulfur (S).

According to another aspect of the present invention, there is provided a method of manufacturing a thin film solar cell module structure,

Depositing and stacking a first rear electrode having transparency on the first surface of the transparent substrate;

Depositing and stacking a second rear electrode comprising a metal nitride layer on the first rear electrode;

Performing a first laser scribing to separate a first laminate structure including the first back electrode and the second back electrode;

Depositing and laminating a light absorbing layer including a metal chalcogenide on the second rear electrode;

Performing a second laser scribing by irradiating a laser onto a second surface of the transparent substrate facing the first surface to separate a second laminated structure including the second back electrode and the light absorbing layer;

Depositing and stacking a transparent electrode on the light absorbing layer; And

And performing a third laser scribing by irradiating a laser onto the second surface of the transparent substrate to separate a third laminated structure including the second rear electrode, the light absorbing layer, and the transparent electrode do.

In one embodiment, the metal nitride layer may comprise a metal nitride represented by the following Formula 1:

≪ Formula 1 >

M _x (C _y N _1-y ) _{1 -x}

In Formula 1, 0.4? X? 0.9, 0? Y? 0.1,

M is at least one selected from tungsten (W), molybdenum (Mo), tantalum (Ta) and titanium (Ti).

In one embodiment, performing the second laser scribing and performing the third laser scribing may use the second back electrode as a sacrificial layer. The second back electrode is characterized by being susceptible to thermal shock at very high heating rates, for example, above 1 x 10 ⁸ 캜 / s, and may include materials with an electrical resistivity of less than or equal to 1 x 10 ^-2 Ω · cm.

In one embodiment, the first to third laser scribing may be performed by a pulsed laser scriber with a pulse width of 0.005 to 50 nanoseconds (ns).

In one embodiment, the pulsed laser scriber can perform laser scribing with a laser intensity of 0.45 W or less.

In one embodiment, the light absorbing layer may be deposited at a temperature of 400 to 580 캜.

In one embodiment, the method of fabricating the thin film solar cell module structure may include the steps of depositing and depositing a transparent electrode on the light absorbing layer,

Depositing and stacking an auxiliary layer on the light absorbing layer; And

And depositing and depositing a transparent electrode on the auxiliary layer,

The second laminate structure may include the second back electrode, the light absorbing layer, and the auxiliary layer, and the third laminate structure may include the second back electrode, the light absorbing layer, the auxiliary layer, and the transparent electrode. have.

In one embodiment, the auxiliary layer may comprise at least one of a buffer layer or a high-resistance window layer.

According to the manufacturing method and the module structure of the thin film solar cell module structure, when the conventional molybdenum (Mo) is applied to the rear electrode, since the rear electrode using Mo is opaque to the laser light, , There was no way to remove only the CIGS light absorbing layer, the buffer layer and the transparent window layer formed thereon while preserving the Mo back electrode upon laser scribing, but the transparent material having excellent light transmittance to the rear electrode layer The present invention can be applied to a surface adjacent to a substrate, and a substrate-entering laser system can be applied to a scribing process for modularizing a thin film solar cell.

Further, when a metal nitride layer is introduced between the rear electrode (hereinafter, referred to as "transparent electrode") to which the transparent material is applied and the light absorption layer, the metal nitride layer is formed by rapid thermal expansion in a pulse laser incidence environment heated at 1000 ° C. for several tens of nanoseconds Due to the thermal shock, the metal nitride layer is peeled off, thereby facilitating the interface separation between the first rear electrode and the light absorption layer. Accordingly, when the CIGS (Copper-Indium-Gallium-Selenide) thin-film photovoltaic module is manufactured, the separation of the light absorption layer is facilitated, and the laser intensity required for processing can be lowered. As a result, thermal diffusion to the first rear electrode using a transparent conductive oxide (TCO) can be minimized, so that the selective processability of only the light absorbing layer can be improved.

It is also necessary to use expensive lasers such as picosecond (ps) and femtosecond (fs) pulsed lasers to prevent thermal diffusion to the periphery caused by high heat accumulation since the optical absorption layer can be removed with only a relatively low temperature heating none. Therefore, CIGS solar cell modules can be fabricated using low-cost nanosecond (ns) pulsed laser scriers, which can lower manufacturing costs.

In addition, the use of the double-layer rear electrode of the transparent electrode / metal nitride layer can reduce the interference effect (for example, reaction product formation, incomplete junction formation, etc.) with the transparent material caused by CIGS deposition, It is possible to produce a high efficiency solar cell module. Further, by controlling the composition and structure of the metal nitride layer, the fill factor (FF) of the solar cell can be increased by lowering the electrical resistivity of the rear electrode compared with the case of using only the transparent rear electrode.

In addition, the introduced metal nitride layer can effectively prevent impurity diffusion from the substrate or the transparent rear electrode in the light absorption layer deposition process. Thus, the quality of the light absorbing layer can be improved and the photoelectric conversion efficiency can be increased.

In addition, when only a transparent oxide material is used as a back electrode, charge blocking due to a reaction formation (Ga ₂ O ₃ ) between a transparent rear electrode and a light absorption layer formed at a high temperature deposition temperature (550 ° C) Lt; / RTI > Therefore, in order to suppress such Ga ₂ O ₃ formation, it is necessary to apply a low-temperature CIGS deposition process at 500 ° C. or lower. However, when a metal nitride layer is introduced, since a reaction product is not generated, a high-temperature process step of 550 ° C or more can be performed, thereby widening the cell manufacturing process window for high efficiency.

In addition, when the thin film solar cell module structure according to the present invention is applied, when the light absorbing layer is processed by a laser of the incident incidence type (P4 scribing) to ensure transparency, the sacrificial layer of the second rear electrode composed of the metal nitride layer As a result, laser processing performance is improved. Also, as shown in FIG. 1, in comparison with the case of applying a substrate-incidence laser processing method to a conventional CIGS thin-film solar module composed of only Mo back electrodes, when the TCO proposed in the present technology is used as a part of a back electrode The laser processability is significantly improved.

Furthermore, when this technology is applied to a window type solar module, reflected light interference phenomenon occurs due to the indoor light source on the transparent material layer / metal nitride layer, the glass substrate / transparent material layer, do. By controlling the distance between each interface constituting the rear electrode and the material characteristics of the metal nitride layer and the interface adhesive layer, it is possible to control the reflected light interference effect, so that the window type solar module is expected to have excellent aesthetic effect .

1 is a schematic diagram of a single integrated thin film solar cell module to which a conventional Mo back electrode is applied.
2 is a schematic view illustrating a manufacturing process of the conventional thin film solar cell module of FIG.
3 is a schematic view of a thin film solar cell module structure having a multilayered rear electrode composed of a transparent electrode and a metal nitride layer according to an embodiment of the present invention.
4 is a schematic view of a concept of laser scribing according to second through third patterning in the thin film solar cell module of FIG.
5 is a schematic view illustrating a manufacturing process of the thin film solar cell module of FIG.
6 is a schematic diagram of a CIGS thin film solar cell structure including a tungsten nitride (WN) thin film according to an embodiment of the present invention in a rear electrode structure.
7 is a SEM photograph showing the phenomenon of the photoabsorption peeling found in a solar cell including a WN thin film as a back electrode structure.
FIG. 8 is a graph showing the current-voltage characteristics of the CIGS thin film solar cell of Example 1 and Comparative Examples 1 to 3. FIG.
9 (a) is an SEM photograph of the microstructure of a CIGS thin film of a cell to which a 450 DEG C CIGS thin film process using a Mo back electrode according to Comparative Example 1 is applied.
9 (b) is a SEM photograph of the microstructure of a CIGS thin film of a cell to which a 450 < 0 > C CIGS thin film process using a back electrode according to Example 1 is applied.
10 is an optical microscope (OM) and SEM photographs of a CIGS light absorption layer processing result in a substrate-incident ns pulse laser (beam size 50 탆, 0.24 W) in an SLG / ITO / CIGS cell.
11 is OM and SEM photographs of a CIGS light absorption layer processing result of a ns pulse laser (beam size 40 탆, 0.11 W) in a SLG / ITO / CIGS cell.
12 is OM and SEM photographs of CIGS light absorbing layer processing results of a ns-pulse laser (beam size 26 탆, 0.05 W) on a SLG / ITO / CIGS cell.
13 is an OM photograph of a CIGS light absorption layer subjected to a ns pulse laser application in a SLG / ITO / Mo / CIGS cell by laser intensity.
FIG. 14 is an OM photograph of a CIGS light absorption layer according to laser intensity applied to a substrate-incident ns pulse laser in an SLG / ITO / WN / Mo / CIGS cell according to an embodiment of the present invention.

The following detailed description of the invention refers to the accompanying drawings, which illustrate, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with an embodiment. It is also to be understood that the position or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly explained. In the drawings, like reference numerals refer to the same or similar functions throughout the several views.

Hereinafter, a module structure of a thin film solar cell according to one embodiment and a method of manufacturing the same will be described in detail with reference to the drawings.

According to an aspect of the present invention, a module structure of the thin film solar cell includes a transparent substrate; A first rear electrode stacked on the transparent substrate and having transparency; A second rear electrode stacked on the first rear electrode, the second rear electrode including a metal nitride layer; A light absorbing layer stacked on the second rear electrode and including a metal chalcogenide; And a transparent electrode laminated on the light absorption layer, wherein at least a part of the first lamination structure including the first rear electrode and the second rear electrode is formed so as to be perpendicular to the lamination direction of the first lamination structure At least a part of the second lamination structure including the second rear electrode and the light absorbing layer is separated in the first direction, and the second rear electrode, the light absorbing layer, and the transparent electrode are separated in the first direction, At least a portion of the third stacked structure including the first stack is separated in the first direction.

In one specific example, the module structure of the thin film solar cell further comprises an auxiliary layer disposed between the light absorbing layer and the transparent electrode, and the second lamination structure includes the second back electrode, the light absorbing layer and the auxiliary Layer, and the third laminated structure may include the second rear electrode, the light absorbing layer, the auxiliary layer, and the transparent electrode.

According to another aspect of the present invention, there is provided a method of fabricating a thin film solar cell module, comprising: depositing and laminating a first rear electrode having transparency on a first surface of a transparent substrate; Depositing and stacking a second rear electrode comprising a metal nitride layer on the first rear electrode; Performing a first laser scribing to separate a first laminate structure including the first back electrode and the second back electrode; Depositing and laminating a light absorbing layer including a metal chalcogenide on the second rear electrode; Performing a second laser scribing by irradiating a laser onto a second surface of the transparent substrate facing the first surface to separate a second laminated structure including the second back electrode and the light absorbing layer; Depositing and stacking a transparent electrode on the light absorbing layer; And performing a third laser scribing by irradiating a laser onto a second surface of the transparent substrate to separate a third laminated structure including the second rear electrode, the light absorbing layer, and the transparent electrode; .

In one specific example, the manufacturing method of the thin film solar cell module structure may include depositing and depositing an auxiliary layer on the light absorption layer, instead of depositing and stacking the transparent electrode on the light absorption layer; And depositing and laminating a transparent electrode on the auxiliary layer, wherein the second laminate structure includes the second back electrode, the light absorbing layer, and the auxiliary layer, and the third laminate structure includes the second A back electrode, the light absorption layer, the auxiliary layer, and the transparent electrode.

For example, the auxiliary layer may comprise at least one of a buffer layer or a high-resistance window layer.

As used herein, 'chalcogenide' refers to a material comprising a Group VI element, such as sulfur (S) and / or selenium (Se), and the metal chalcogenide may be, for example, Cu _1-x , Ga _x ) (Se, S) ₂ (CIGS) or Cu ₂ ZnSn (Se, S) ₄ (CZTS), but is not limited thereto.

In the present specification, the first to third laminated structures refer to a layer structure in which respective substrates, electrodes, or layers forming the thin film solar cell module structure of the present invention are combined with each other. Will be more clearly understood and understood.

FIG. 3 schematically shows a structure of a thin film solar cell module capable of transmitting a substrate incident laser having a multilayered rear electrode composed of an electrode and a metal nitride layer having excellent light transmittance according to an embodiment of the present invention, and FIG. 4 3 schematically illustrates the concept of laser scribing according to the second to third patterning in the thin film solar cell module of FIG. 3, and FIG. 5 schematically shows a manufacturing process of the thin film solar cell module of FIG.

Referring to FIG. 3, a thin film solar cell 1 according to an embodiment of the present invention includes a transparent substrate 10; A first rear electrode (30) stacked on the transparent substrate (10) and having transparency; A second rear electrode (35) stacked on the first rear electrode (30) and including a metal nitride layer; A light absorbing layer (40) stacked on the second rear electrode (35) and including a metal chalcogenide; A transparent electrode 70 laminated on the light absorbing layer 40; And has a monolithic integrated module structure including a buffer layer 50 and a high-resistance window layer 60 disposed between the light absorbing layer 40 and the transparent electrode 70.

In the thin film solar cell 1, at least a part of the first laminated structure 20a including the first rear electrode 30 and the second back electrode 35 is formed in the lamination direction of the first laminated structure 20a Including the second rear electrode 35, the light absorbing layer 40, the buffer layer 50, and the high-resistance window layer 60, which are separated in a first direction (X direction) perpendicular to the first direction (Y direction) At least a part of the laminated structure 20b is separated in the first direction (X direction), and the second back electrode 35, the light absorbing layer 40, the buffer layer 50, the high resistance window layer 60, At least a part of the third lamination structure 20c including the electrode 70 is separated in the first direction (X direction).

For example, the first rear electrode 30 and the second rear electrode 35 may be combined to form a multi-layer rear electrode.

At this time, the first rear electrode 30 and the transparent electrode 70 may be connected in series at the separated portion of the second laminated structure 20b.

4, in the present invention, in order to form a structure in which a plurality of separated cells of the thin film solar cell 1 are connected in series, when patterning to remove a part of the laminated layers including the light absorbing layer, (10). That is, the laser is incident on the second surface of the transparent substrate 10, which is opposite to the first surface, rather than the first surface of the transparent substrate 10 on which the transparent electrodes and the like are integrated as in the prior art, do. At this time, the second rear electrode 35 is used as a sacrificial layer for efficient processing of the light absorbing layer at the time of the second laser scribing P2 and the third laser scribing P3.

For example, in order to form the thin film solar cell 1, the first lamination structure 20a including the first and second back electrodes 30 and 35 is formed in a first direction (X direction) A first laser scribing P1 for separating the first layered structure 20a and the second layered structure 20b in parallel to each other, a second backside electrode 35, a light absorbing layer 40, a buffer layer 50 A second laser scribing part P2 for separating the second stack structure 20b including the high resistance window layer 60 in the first direction (X direction) and the second laser scribing part P2 for separating the second rear surface part 35, A third laser for separating the third laminated structure 20c including the light absorbing layer 40, the buffer layer 50, the high-resistance window layer 60 and the transparent electrode 70 in the first direction (X direction) Scribing (P3) can be performed.

When the laser scribing is performed as described above, the laser beam is not absorbed by the transparent substrate 10 during one or more of the first to third laser scribing (P1, P2, P3) If a laser of a wavelength that can be absorbed is incident on the transparent substrate 10 side, the material to be removed can be peeled off at the interface due to stress concentration due to abrupt thermal expansion without melting, so scribing is possible with a small energy.

In addition, since the incidence direction of the laser and the direction of removing debris are completely distinguished, problems such as re-adsorption of debris do not occur. Furthermore, since it is not necessary to undergo a melting process, the incident energy is low and thermal diffusion to the surrounding material is not a big problem, it is not necessary to use a pulse laser of a picosecond (ps) or less. Therefore, there is an advantage that a relatively low-cost nanosecond (ns) laser can be applied.

In the conventional CIGS solar cell module, since the molybdenum (Mo) rear electrode typically used is opaque to the laser beam, the Mo back electrode is preserved during the second and third scribing by applying the substrate incident laser system There is no method for removing only the CIGS light absorption layer, the buffer layer and the transparent window layer formed on the substrate. On the other hand, when a transparent material transparent to laser light is applied to the rear electrode, the electrical resistivity is higher than that of metal, thereby increasing the series resistance of the solar cell module. To overcome this problem, There is a restriction that the cell width must be designed very small.

In the present invention, even if a transparent material is applied to the first rear electrode 30, the diffusion of the impurity and the interfacial reaction from the SLG / ITO are suppressed due to the presence of the second rear electrode 35 including the metal nitride, It is possible to suppress the deterioration of the efficiency due to the replacement of the rear electrode regardless of the temperature.

In addition, by substituting the first rear electrode 30 with a transparent electrode having excellent light transmittance and concentrating the laser light absorption on the second rear electrode 35 including the metal nitride by applying a laser with a wavelength band that allows transmission, It may cause peeling of the electrode / CIGS interface.

Among the thin film solar cells 1, the transparent substrate 10 is characterized by having a light transmittance of 90% or more in a visible light or near infrared ray band (wavelength band of about 450 to about 1100 nm), and soda lime glass, polyimide, can do. When a glass substrate is used as the transparent substrate 10, a visible to near infrared wavelength laser (for example, about 1064 nm, about 532 nm) which is not absorbed by the glass substrate can be used.

In this case, when the visible light region wavelength (about 532 nm) is applied during the second and third laser scribing P2 and P3, the light passes through the first rear electrode 30, Heat is concentrated on the surface of the light absorbing layer 40 adjacent to the first back electrode 30 and the interface between the first rear electrode 30 and the light absorbing layer 40 due to the rapid thermal expansion of the second rear electrode 35, Peeling can be easily induced. Further, in the case of the region where the second laser scribing P2 is performed, the interfacial adhesion layer 33 and the ohmic contact layer 36 can be removed together during laser scribing, The effect on the efficiency of the thin film solar cell module is very small.

In one specific example, the first rear electrode may include a material having a light absorption of 20% or less and a specific resistance of 1 x 10 < ^-2 & gt ^; OMEGA .cm or less in the visible light or near infrared region. Also, the first rear electrode may be formed to a thickness within the range of 100 to 2000 nm, and the second rear electrode may be formed to a thickness within the range of 1 to 200 nm, preferably 5 to 50 nm, But is not limited thereto. If the thickness of the second rear electrode is too thick, the peeling of the thin film may be intensified during or after the CIGS thin film deposition process by the subsequent process.

The first rear electrode may include a transparent conductive oxide (TCO) including at least one selected from the group consisting of indium (In), zinc (Zn), and tin (Sn) And a transparent electrode having a carbon material dispersed therein, the transparent electrode including at least one of graphene and carbon nanotubes, but not limited to, a visible light and a visible light, Any substance can be used as long as it has low absorption in the near-infrared band.

The oxide of indium may be, for example, indium tin oxide (ITO), the oxide of zinc may be, for example, ZnO, and the oxide of tin may be, for example, fluorine tin oxide (FTO).

The multi-layered transparent electrode means a transparent electrode composed of a TCO / metal layer (or nanowire layer) / TCO, and between the TCO and the metal layer, or between the metal layer and the TCO, . The metal layer may comprise, for example, one of Mo, W, Ta, Cr, Ni and Ti.

For example, when the TCO is used as the first back electrode, light absorption at a wavelength band of visible light (about 532 nm wavelength) is very small, while light absorption at a near infrared or infrared wavelength band (about 1064 nm) is considerably high.

Therefore, in the first laser scribing P1, a laser of a wavelength band (for example, 532 nm) of visible light as well as a laser of a near infrared to infrared wavelength band (for example, 1064 nm) The TCO should be maintained and the laser of the visible light wavelength band (for example, 532 nm) should be applied at the time of the second laser scribing (P2) and the third laser scribing (P3) For example, a CIGS layer) and layers or electrodes stacked on the light absorption layer. In other words, there is a problem in that the optical wavelength that can be selectively absorbed in each layer must be considered for laser processing, which results in poor processability.

However, in the case of the thin-film solar cell module structure in which the metal nitride layer is introduced as in the present invention, by using the characteristic of the metal nitride layer capable of combining various elements, it is possible to obtain a near- 1064 nm) laser can be applied. In other words, when the rear electrode structure including the metal nitride layer is applied as compared with the conventional TCO / CIGS cell structure, the laser wavelength range that can be selected for the scribing process is widened, It is not necessary to apply different laser processing, and laser processing is easier.

In one specific example, the second back electrode may comprise a material which is susceptible to thermal shock at a very high heating rate, for example 1 x 10 ⁸ 캜 / s, and whose electrical resistivity is less than or equal to 1 × 10 ^-2 Ω · cm have.

The second rear electrode may include a conductive ceramic material having a low resistance to thermal shock when heated at a high speed.

The second rear electrode may be formed of a single layer or multiple layers including at least one of the metal nitrides represented by Formula 1. For example, the metal nitride layer may be formed by mixing two or more metals among W, Mo, Ta, and Ti, but is not limited thereto. For example, some of the nitrogen (N) in the metal nitride may be substituted with carbon (C), but the present invention is not limited thereto. For example, the metal nitride layer may include at least one selected from WN _x , MoN _x , TiN _x , and TaN _x (0.4? _X ? 0.9), but is not limited thereto.

When the second back electrode is comprised of multiple layers, it may be a periodic alternation of the metal nitride layer or a periodic alternation of the metal nitride layer and the metal layer pair. Here, the metal layer may include tungsten (W), molybdenum (Mo), tantalum (Ta), and titanium (Ti).

An interfacial adhesion layer 33 for enhancing the interfacial adhesion between two layers can be introduced between the first back electrode 30 and the second back electrode 35. The interfacial adhesion layer may include at least one of Mo, W, Ta, Cr, Ni, and Ti, but is not limited thereto and may be adjusted to a thickness of about 1 to about 50 nm, preferably about 5 to 20 nm . If the thickness of the interfacial adhesion layer is too thin outside the above range, the function as the interfacial adhesion layer becomes weak. On the other hand, if the thickness is excessively large, the laser processability may be adversely affected.

In one specific example, the light absorption layer is formed of one or more selected from among copper (Cu) or silver (Ag), indium (In), gallium (Ga), aluminum (Al), zinc (Zn) One or more selected, and one or more selected from selenium (Se) or sulfur (S).

A hole having a high work function is formed between the light absorbing layer 40 and the second back electrode 35 so that hole injection into the light absorbing layer 40 as a p- A contact layer 36 can be introduced.

The ohmic contact layer 36 may be stable at about 400 to 600 占 폚, and the work function may be at least about 5 eV. The ohmic contact layer may comprise an interface control material and may include one or more of Mo, gold (Au), an oxide of Mo, an oxide of W, an oxide of Ni, SnO: In (ITO) And the thickness may be adjusted from about 1 to about 50 nm, preferably from about 5 to 20 nm. If the thickness of the ohmic contact layer is too small, the peeling phenomenon of the CIGS thin film becomes excessive, the laser processability may be lowered, and the photoelectric conversion efficiency may be reduced.

On the other hand, in the case of a TCO material having no known absorption of visible light, the electrical resistivity is higher than that of metal. For example, in the case of ITO having the highest conductivity among the TCO materials, the resistivity is about 1 × 10 ^-4 Ω · cm, which is about 10 times higher than about 1 × 10 ^-5 Ω · cm of the conventional Mo back electrode. This high resistance increases the series resistance of the solar cell module together with the series resistance by the TCO layer used as the window layer. To overcome this, it is necessary to increase the thickness of the back electrode material or to make the cell width very small There was a restriction to be done.

The inventors of the present application have confirmed that this problem can be solved by improving the electrical conductivity of the metal nitride or increasing the conductivity of the ohmic contact layer in the second rear electrode including the metal nitride.

4, since the second back electrode 35 and the ohmic contact layer 36 are removed during laser scribing, the region where the second laser scribing P2 is performed and the region where the second laser scribing P2 is performed, The electric resistance of the region where the ice P3 is performed increases. However, since the scribing widths of the second to third laser scribing lines are as small as about 10 占 퐉 to 200 占 퐉, the resistance increase due to the removal of the conductive layer in the corresponding region is limited. In addition, the region where the second laser scribing P2 is performed can be minimized through the deposition of the transparent electrode 70, and the region P3 can be minimized by adjusting the scribing width.

Meanwhile, FIG. 5 schematically shows a manufacturing method of the thin film solar cell module structure of FIG.

The method of fabricating the thin film solar cell module structure includes depositing and laminating a first rear electrode 30 having transparency on a first surface 10a of a transparent substrate 10; Depositing and stacking a second rear electrode (35) including a metal nitride layer on the first rear electrode (30); Performing a first laser scribing (P1) to separate a first stack structure (20a) comprising the first back electrode (30) and a second back electrode (35); Depositing and laminating a light absorbing layer (40) including a metal chalcogenide on the second rear electrode (35); Depositing and stacking a buffer layer (50) and a high-resistance window layer (60) on the light absorption layer; In order to separate the second laminate structure 20b including the second rear electrode 35, the light absorbing layer 40, the buffer layer 50 and the high-resistance window layer 60, the transparent substrate 10 And performing a second laser scribing (P2) by making a laser incident on a second surface (10b) facing the first surface (10a) of the first surface (10a); Depositing and depositing a transparent electrode (70) on the high-resistance window layer (60); And the third stack structure 20c including the second back electrode 35, the light absorbing layer 40, the buffer layer 50, the high-resistance window layer 60, and the transparent electrode 70 are separated , And performing a third laser scribing (P3) by making a laser incident on a second surface (10b) of the transparent substrate (10).

For example, the first rear electrode 30 and the second rear electrode 35 may form a double layer rear electrode 30, 35.

As in FIG. 5 (b), the first layered structure 20a of the double layered backside electrodes 30, 35 is separated or patterned by the first laser scribing P1, (20a).

At this time, the laser can be applied to both the incidence of the substrate (solid line) or the incidence of the thin film on the opposite side (dotted line). However, when a laser beam of a wavelength that can be absorbed by the double layer backside electrodes 30 and 35 to be simultaneously removed is incident on the transparent substrate 10 side without being absorbed by the transparent substrate 10, stress due to abrupt thermal expansion Since it can be peeled from the interface by concentration, scribing is possible with a small energy. Accordingly, the first laminated structure 20a is separated at regular intervals in the first direction (X direction).

Referring to FIG. 5 (c), after the scribing process of the double layer rear electrodes 30 and 35, the light absorption layer 40 is deposited and deposited. Also, one or more layers of the buffer layer 50 and the high-resistance window layer 60 may be deposited on the light absorption layer 40 to be deposited. Thereafter, a second laser scribing step P2 for separating the second laminated structure 20b is performed. Similarly, in the same manner as in the first laser scribing step, the laser enters the second surface 10b of the transparent substrate 10 in a solid line manner to perform a scribing process.

The second laser scribing (P2) process may be performed in a region adjacent to the region where the first laser scribing (P1) process has been performed. Accordingly, the second laminated structure 20b is separated in parallel with the P1 working line in the region adjacent to the isolation region (P1 region) of the first laminated structure 20a. At this time, since the second rear electrode 35 is used as a sacrifice layer, it can be removed together.

Referring to FIG. 5D, the transparent electrode 70 is deposited, and the first rear electrode 30 and the transparent electrode 70 in the region (P2 region) where the second laser scribing process is performed 70). This completes the serial connection between adjacent cells. Thereafter, a laser is incident on the second surface 10b of the transparent substrate 10 to perform a third laser scribing process. At this time, the second back electrode 35 is used as a sacrifice layer, and a portion of the third stack structure 20c is removed together.

Referring to FIG. 5 (e), as a result, adjacent cells are electrically insulated and separated.

In the case of the above-mentioned thin film solar module, the application of the additional fourth laser scribing (P4) process after modularization is easy, and the light transmittance can be freely adjusted. Further, it is easy to adjust the line width and the interval, so that the function as a skylight window can be performed without visual discomfort. At this time, the incidence of the laser during the fourth laser scribing (P4) may be parallel to the first to third laser scribing (P1, P2, P3) or may be vertical. It is advantageous to apply the fourth laser scribing P4 perpendicularly to the existing first to third laser scribing P1, P2, P3 in order to avoid greater deterioration than the inevitable photocurrent reduction for increasing the light transmittance will be. Further, in addition to the above-mentioned through-type straight line, it is possible to realize patterns of various shapes such as a circle. Through the design of the fourth laser scribing (P4), it is possible to add various types of patterns or pictures to the window type BIPV.

In the case of the transparent material / metal nitride layer double-layered backside electrodes 30 and 35 formed on the glass substrate as described above, reflection interference due to the room illumination of the transparent material / metal nitride layer interface, the transparent material / glass substrate interface, It is possible to implement various colors in the window type BIPV module from the viewpoint of the resident. Further, the color adjustment function of the in-house occupant's time can be added by controlling the material and the characteristics of the interface adhesive layer introduced into the interface of the transparent material / metal nitride layer.

Hereinafter, the effects of the present invention will be described in detail through experiments.

First, we compared the effect on the cell efficiency when the Mo thin film widely used as the back electrode in the conventional CIGS solar cell was replaced with ITO.

FIG. 6 schematically shows a CIGS thin film solar cell structure including a tungsten nitride (WN) thin film according to an embodiment of the present invention in a rear electrode structure.

Generally, a problem that arises when ITO is applied to the back electrode of a CIGS solar cell is that the formation of the n-type Ga ₂ O ₃ reaction layer which forms a high interface barrier of the ITO / CIGS interface and the formation of the Mo metal Is an increase in series resistance due to a relatively high specific resistance relative to the electrode. Therefore, the CIGS light absorbing layer was deposited at a low temperature of about 450 캜 to suppress the Ga ₂ O ₃ reaction layer formation.

For example, CdS with a thickness of about 50 nm is deposited by chemical bath deposition (CBD), and then a high resistance ZnO (about 50 nm thick) and Al-doped ZnO (AZO) 500 nm thick).

In order to enhance the ohmic contact property between the ITO rear electrode and the CIGS light absorbing layer of 200 nm thickness, a back electrode structure (Comparative Example 3) in which a 30 nm thick Mo thin film was added, and an ITO thin film and Mo The back electrode structure (Example 1) in which tungsten nitride (W _x N _1-x , where x is about 0.5) was added as a sacrificial layer to a thickness of 30 nm between the thin films was compared.

In Example 1, the tungsten nitride (WN) thin film was deposited using a pulsed DC magnetron sputtering method, and a tungsten (W) target having a diameter of 3 inches was formed by using Ar and N ₂ in a volume ratio of 1: 5 (20 kHz, 80% duty cycle) under a pressure of 3 mtorr using a mixed gas. The resultant was sputtered at a substrate temperature of 450 ° C. for 5 minutes. Thus deposited W _x N _{1 -x} specific resistance of the layer was about 1.5 × 10 ^- was determined to be ⁴ Ω · cm.

7 is a SEM photograph showing the phenomenon of the photoabsorption peeling found in a solar cell including a WN thin film as a back electrode structure.

When the tungsten nitride (WN) thin film is applied as a sacrificial layer, the layers above the CIGS thin film tend to be easily peeled off after the cell fabrication, as shown in the SEM photograph of FIG. It is presumed that there is a problem in the interface adhesion between the WN thin film and the underlying ITO layer. Therefore, in order to solve this problem, the Mo layer was deposited to a thickness of 10 nm or less between the ITO and WN thin films in the first embodiment.

Except for using Mo (Comparative Example 1), ITO (Comparative Example 2), ITO / Mo (Comparative Example 3) and ITO / WN / Mo (Example 1) as the back electrode in the CIGS thin film solar battery cell structure The CIGS thin film solar cell was fabricated by charging the rear electrode structure according to Example 1 and Comparative Examples 1 to 3 to each subsequent deposition process at the same time in the same manner as the above-described method of manufacturing the rear electrode structure.

The CIGS thin film solar cell of Example 1 and Comparative Examples 1 to 3 was compared with the cell efficiency factor measured by the current-voltage curve measured under the solar mass standard (air mass 1.5, one sun condition) Respectively.

FIG. 8 is a graph showing the current-voltage characteristics of the CIGS thin film solar cell of Example 1 and Comparative Examples 1 to 3. FIG.

Photoelectric conversion efficiency factor of CIGS thin film solar cell by back electrode structure Rear electrode structure efficiency [%] V _OC [mV] J _SC [mA / cm ² ] FF [%] Comparative Example 1 SLG / SiOx / Mo (500 nm) 16.2 0.640 34.1 74.3 Comparative Example 2 SLG / ITO (200 nm) 13.2 0.609 34.3 62.9 Comparative Example 3 SLG / ITO (200 nm) / Mo (30 nm) 14.1 0.621 33.3 68.1 Example 1 SLG / ITO (200 nm) / WN / Mo (30 nm) 15.2 0.641 33.3 71.0

Referring to FIG. 8 and Table 1, the optical voltage and the FF were significantly lowered in Comparative Example 2 using the ITO rear electrode compared to Comparative Example 1 using the Mo back electrode. This is probably due to the increase in series resistance due to the high sheet resistance of the ITO back electrode, the interface barrier due to reaction products at the ITO / CIGS interface, and the deterioration of the CIGS light absorption layer due to the diffusion of impurities from ITO and the substrate. In Comparative Example 3 using the ITO / Mo structure, it was estimated that the FF and the light voltage were somewhat restored, and the series resistance and the improvement of the interfacial characteristics were improved by adding Mo (30 nm). On the other hand, In the case of Example 1, the optical voltage was increased to the level of Comparative Example 1 using the Mo electrode and FF was greatly improved, so that the introduction of WN contributed substantially to the improvement of photoelectric conversion efficiency. The higher series resistance than the Mo electrode is because the back electrode structure of ITO / WN / Mo is more resistant than Mo single electrode. The remarkable effect of the introduction of WN is that the photovoltage is improved and recovered to the same level as the Mo single electrode. This is presumably because the WN layer effectively blocked impurity diffusion from the bottom (SLG / ITO).

9 (a) is an SEM photograph of a microstructure of a CIGS thin film of a cell to which a 450 DEG C CIGS thin film process using a Mo back electrode according to Comparative Example 1 is applied, FIG. 9 (b) SEM photographs of the microstructure of the CIGS thin film of the cell using the electrode at 450 ℃ CIGS thin film process.

9 (a) and 9 (b), when the WN thin film was introduced as in Example 1, the crystal grains of the CIGS light absorbing layer were generally increased as compared with the Mo back electrode according to Comparative Example 1, This is because Na diffusion is blocked from the sodalime glass substrate and the diffusion rate of CIGS thin film constituent elements is accelerated. As a result, the crystallinity of the CIGS thin film was increased, and the defect density causing the photovoltage loss was greatly reduced.

FIGS. 10 to 12 show results of processing of a CIGS light absorption layer on a substrate-entering nanosecond pulsed laser with different beam sizes for SLG / ITO / CIGS / CdS / i-ZnO / Optical microscope (OM) and electron microscope (SEM) photographs.

When the laser beam size is 50 ㎛, the ITO / CIGS interface separation by laser heating is effective as shown in the optical microscope and electron microscopic observation of FIG. 10, so that CIGS thin film processing is possible while minimizing the damage of ITO. However, as shown in Figs. 11 and 12, as the beam size decreased to 40 탆 and 26 탆, the damage of ITO tended to become extremely severe. As a result, in the ITO / CIGS structure, It was not easy to realize the line width.

FIG. 13 is a graph showing the relationship between the number of nano-sized superlattices of 532 nm and the number of nanowires of a CIGS thin film solar cell (SLG / ITO / Mo / CIGS / CdS / i-ZnO / AZO structure) having SLG / ITO / Mo (30 nm) Experimental results of the CIGS light absorbing layer and the subsequent thin film layers are shown by an optical microscope and are shown by laser intensity. As shown in Fig. 13, in the Mo back electrode structure, relatively high laser intensity is required for processing the light absorbing layer, and in the result of the 0.55 W machining process, the damage of the ITO thin film, it's difficult.

On the other hand, when the WN sacrificial layer is applied, it is possible to fabricate a light absorbing layer with minimized ITO damage. FIG. 14 is an OM photograph of a CIGS light absorption layer according to a laser intensity applied to a substrate using an ns pulse laser method in a SLG / ITO / WN / Mo / CIGS cell according to an embodiment of the present invention.

Comparing the results of FIG. 14 with the results of FIG. 13, it can be seen that not only the light absorption layer can be processed at lower laser intensities, but also the processing conditions capable of CIGS processing without damaging the ITO thin film Could.

As described above, in order to improve the photoelectric conversion efficiency of the single-contact thin-film solar module, it is necessary to reduce the line width of P2 and P3 to about 10 to 20 μm to reduce the dead area of photovoltaic generation, It is necessary to prevent shunting of each cell in the module due to damage and debris such as melting phenomenon of the light absorbing layer and surrounding materials occurring during the process.

To this end, the laser processing technique should be applied to the second and third scribing (P2, P3). Currently, the transparent window layer incidence (opposite side of substrate) method is applied, lt; / RTI > (ps) < RTI ID = 0.0 > level, < / RTI > However, the price of a picosecond (ps) pulse laser or a femtosecond (fs) pulse laser is high, thereby increasing the initial investment cost of the photovoltaic module manufacturing line.

In addition, when a laser of a transparent window layer incidence system is used, since the laser is incident in the debris removal direction during scribing, there arises a problem that the debris is fixed to the scribe area. If a relatively inexpensive nanosecond (ns) pulse laser with a pulse width in the range of 1 to 50 ns can be applied to the substrate incidence method, the module efficiency can be improved while minimizing the cost increase of the manufacturing process.

In order to cope with the BIPV market of the light emitting window, the amorphous thin film Si solar cell with the commercialized technology removes the opaque light absorbing layer by the laser scribing process and transmits the light to the area where the light absorbing layer is removed, . On the contrary, the CIGS thin film solar module having the structure of FIG. 1 is excellent in the light absorption ability of the light absorption layer and is difficult to transmit light through the regions P1, P2 and P3 due to absorption or reflection by Mo, which is the rear electrode. As mentioned above, since the photoelectric conversion efficiency of CIGS thin film solar cell is very high among the existing thin film solar cells, securing the light transmittance can secure a great competitive power in the BIPV market.

In this CIGS thin film solar cell, as described in the present invention, by introducing the rear electrode structure including WN, it is possible to process the CIGS light absorption layer having a smaller line width while minimizing damage to the transparent rear electrode.

In addition, P2 processability, which is the biggest problem of scribing process for manufacturing CIGS thin film solar module, can be greatly improved, and the module manufacturing technology can be innovated, and P2 and P3 line width can be reduced to 10 ~ 20 ㎛ , The dead zone area can be greatly reduced. This can significantly improve the performance of solar modules.

In addition, in the case of the above-described light emitting window solar module, it is necessary to be able to control various levels of lighting for residents in the room, and to adjust the color in order to respond to aesthetic factors. Aside from active control of mining and color after completion of the product, it should be possible to produce a variety of products with controlled lighting and color matching the requirements of the customer at the production stage. Accordingly, it is expected that the present invention can reduce the cost of the manufacturing process and secure competitiveness in the BIPV market.

Claims (19)

A transparent substrate;
A first rear electrode stacked on the transparent substrate and having transparency;
A second rear electrode stacked on the first rear electrode, the second rear electrode including a metal nitride layer;
A light absorbing layer stacked on the second rear electrode and including a metal chalcogenide; And
And a transparent electrode laminated on the light absorption layer,
Further comprising an interfacial adhesion layer disposed between the first back electrode and the second back electrode,
Wherein the interfacial adhesion layer comprises at least one selected from the group consisting of Mo, W, chromium (Cr), nickel (Ni) and Ti,
The thickness of the interface adhesion layer is 1 to 50 nm,
At least a part of the first lamination structure including the first back electrode and the second back electrode is separated in a first direction perpendicular to the lamination direction of the first lamination structure,
At least a part of the second laminated structure including the second rear electrode and the light absorbing layer is divided in the first direction,
At least a part of a third laminated structure including the second rear electrode, the light absorbing layer and the transparent electrode is separated in the first direction. The method according to claim 1,
Wherein the first rear electrode and the transparent electrode are connected in series at the separated portion of the second laminated structure. The method according to claim 1,
Wherein the second laminate structure includes the second back electrode, the light absorbing layer, and the auxiliary layer, and the third laminate structure includes the second back surface electrode, the light absorbing layer, and the auxiliary layer, An electrode, the light absorption layer, the auxiliary layer, and the transparent electrode. The method of claim 3,
Wherein the auxiliary layer comprises at least one of a buffer layer or a high resistance window layer. The method according to claim 1,
Wherein the first rear electrode comprises a material having a light absorption of 20% or less and a specific resistance of 1 x 10 < ^-2 & gt ^; OMEGA .cm or less in a visible light or near infrared ray band. The method according to claim 1,
Wherein the first rear electrode comprises a transparent conductive oxide (TCO) comprising at least one selected from the group consisting of indium (In), zinc (Zn), and tin (Sn) And a transparent electrode in which a carbon material is dispersed, wherein the carbon material includes at least one of graphene and carbon nanotubes. The method according to claim 1,
Wherein the metal nitride layer comprises a metal nitride represented by the following Chemical Formula 1:
≪ Formula 1 >
M _x (C _y N _1-y ) _{1 -x}
In Formula 1, 0.4? X? 0.9, 0? Y? 0.1,
M is at least one selected from tungsten (W), molybdenum (Mo), tantalum (Ta) and titanium (Ti). The method according to claim 1,
Wherein a thickness of the first rear electrode is 100 to 2000 nm and a thickness of the second rear electrode is 1 to 200 nm. The method according to claim 1,
Wherein the interfacial adhesion layer has a thickness of 1 to 50 nm. The method according to claim 1,
Further comprising an ohmic contact layer disposed between the second back electrode and the light absorbing layer. 11. The method of claim 10,
Wherein the ohmic contact layer comprises at least one selected from the group consisting of Mo, Au, Mo, W, O, ITO, and FTO. 11. The method of claim 10,
Wherein the ohmic contact layer has a thickness of 1 to 50 nm. The method according to claim 1,
Wherein the light absorbing layer comprises at least one selected from the group consisting of copper (Cu) and silver (Ag), at least one selected from among indium (In), gallium (Ga), aluminum (Al), zinc (Zn), and tin (Se) or sulfur (S). Depositing and stacking a first rear electrode having transparency on the first surface of the transparent substrate;
Depositing and stacking a second rear electrode comprising a metal nitride layer on the first rear electrode;
Performing a first laser scribing to separate a first laminate structure including the first back electrode and the second back electrode;
Depositing and laminating a light absorbing layer including a metal chalcogenide on the second rear electrode;
Performing a second laser scribing by irradiating a laser onto a second surface of the transparent substrate facing the first surface to separate a second laminated structure including the second back electrode and the light absorbing layer;
Depositing and stacking a transparent electrode on the light absorbing layer; And
And performing a third laser scribing by irradiating a laser onto the second surface of the transparent substrate to separate a third laminated structure including the second rear electrode, the light absorbing layer, and the transparent electrode Wherein the thin film solar cell module structure is formed on the substrate. 15. The method of claim 14,
Wherein the metal nitride layer comprises a metal nitride represented by the following Chemical Formula 1:
≪ Formula 1 >
M _x (C _y N _1-y ) _{1 -x}
In Formula 1, 0.4? X? 0.9, 0? Y? 0.1,
M is at least one selected from tungsten (W), molybdenum (Mo), tantalum (Ta) and titanium (Ti). 15. The method of claim 14,
Wherein the step of performing the second laser scribing and the step of performing the third laser scribing use the second back electrode as a sacrificial layer. 15. The method of claim 14,
Wherein the first to third laser scribing is performed by a pulsed laser scriber having a pulse width of 0.005 to 50 nanoseconds (ns). 15. The method of claim 14,
Instead of depositing and depositing a transparent electrode on the light absorbing layer,
Depositing and stacking an auxiliary layer on the light absorbing layer; And
And depositing and depositing a transparent electrode on the auxiliary layer,
Wherein the second laminated structure includes the second back electrode, the light absorbing layer and the auxiliary layer, and the third laminated structure includes the second back electrode, the light absorbing layer, the auxiliary layer, and the transparent electrode. (Method for manufacturing thin film solar cell module structure). 19. The method of claim 18,
Wherein the auxiliary layer comprises at least one of a buffer layer or a high resistance window layer.

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