JP2983117B2 - Manufacturing method of thin film solar cell - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a thin-film solar cell for converting light energy such as sunlight into electric energy by bonding using a chalcopyrite-type ternary semiconductor compound thin film.

[0002]

2. Description of the Related Art I-III-VI_TwoTribe chalcopyrite type 3
Original compound thin film, especially CuInSe_Two, CuInS _Two, AgInSe_Two, Ag
InS_TwoHas an optical gap in the range of 1.0 to 1.8 eV,
It is expected to be used as a photoelectric conversion element. In recent years, these
Of thin film solar cell devices
It is gaining more attention as a material. Below this kind of solar cell
For forming chalcopyrite-type ternary compound thin film at low temperature
About the method, CuInSe_TwoThe conventional technology is explained with an example
I do.

[0003] As a method for forming a CuInSe ₂ thin film, a ternary simultaneous vapor deposition method, a selenization method, and the like are known. In the selenization method, a Cu / In laminated film is formed on a substrate at room temperature. In Se diluted with Ar at a substrate temperature of 400 to 550 ° C., for example, 3 to 15
This is a method of forming a CuInSe ₂ thin film having a large particle size of about 3 μm by treating in a gas containing% H ₂ Se for several hours. When the group VI element is S, the treatment is performed in an S atmosphere.

[0004]

During the treatment in the H ₂ Se in the above-mentioned selenization method, Se gas infiltrates on the surface of the substrate, and a Se compound such as a Se compound MoSe ₂ is generated on the Mo electrode layer on the substrate surface. This Se compound has high resistance, and the form factor (F
F). In addition, Se enters the Cu / In laminated film and reacts to cause a volume expansion, and the adhesive force at the interface between the substrate and the CuInSe ₂ thin film is weakened.

[0005] Next, a Cu-In-Se mixed film is formed in the same manner as above using H ₂
When treated in Se, the problem of the substrate / CuInSe ₂ thin film interface does not occur, but the CuInSe ₂ thin film is formed at a relatively low temperature because it starts to react with Se in the film in the process of raising the temperature, and the grain size is about 1 μm.
It did not grow up to about μm, and the efficiency of the manufactured solar cell was low. An object of the present invention is to provide a method for manufacturing a thin-film solar cell having a chalcopyrite-type compound thin film having a large particle diameter formed without forming a group VI element compound on a substrate surface.

[0006]

According to the present invention, there is provided a method of manufacturing a thin-film solar cell having a group I-III-VI chalcopyrite-type ternary compound thin film on a substrate according to the present invention. Periodic table group I element, group III element,
And forming an initial film containing a Group VI element on an electrode on the substrate, and subsequently forming a mixed film of a Group I element and a Group III element without performing a treatment in a Group VI element atmosphere;
Next, by treating in a group VI element atmosphere, the laminated initial film and the mixed film are integrated into an I-III-
It is to be formed with a group VI thin film. VI contained in the initial film
It is effective that the amount of the group element is equal to or less than the sum of the amount of the group I element and the amount of the group III element. Further, the initial film may be a laminated film or a mixed film of each element. Further, it is effective that the substrate temperature during the initial film formation is 400 ° C. or less.

[0007]

By including a Group VI element near the substrate in the initial film, volume expansion near the substrate due to invading gaseous Group VI element is prevented, and I Since the -III-VI group ₂ compound is formed, the formation of the group VI compound on the substrate surface is suppressed. Then, suppressing the substrate temperature to 400 ° C. or less during the formation of the initial film increases the effect of suppressing volume expansion near the substrate and generation of compounds. Also III
Since the group III elements are present only in the vicinity of the substrate, the surface of the formed film reacts with the gaseous group VI elements at a high substrate temperature to obtain I-II.
A group I-VI compound is formed, and the particle size can be increased.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention in producing a CuInSe ₂ thin film solar cell will be described. 1 (a) to 1 (d) show a manufacturing process of a CuInSe ₂ thin film solar cell according to one embodiment of the present invention, in which Mo, Cr, etc. are sputtered on a glass substrate 1 [FIG. 1 (a)]. Lower electrode 2 having a thickness of about 1 μm
[FIG. 2B], a Cu—In—Se mixed film 3 is formed at a substrate temperature of 200 ° C. by a ternary simultaneous vapor deposition method. At this time, for example, control is performed so that Se / (Cu + In) = 1 or less with Cu / In = 0.95. Further, the Cu-In-Se film 3 is formed only in the vicinity of the substrate. For example, Cu corresponding to a Cu film having a thickness of about 0.2 μm is evaporated, and In corresponding to an In film having a thickness of about 0.465 μm is formed. When evaporating, the shutter of the Se evaporation source is closed when Cu corresponding to a thickness of 0.1 μm or less is evaporated,
Thereafter, a Cu-In mixed film 4 is formed [FIG. Then, an atmosphere containing Se, for example, H ₂ Se diluted with Ar
When treated in a gas containing about 15% at a substrate temperature of about 400 ° C. for about 1 hour, it reacts with Se thermally decomposed from H ₂ Se.
A CuInSe ₂ thin film 5 is formed [FIG.

[0009] CuInSe ₂ thin film 5 formed by this method
Is a film having good adhesion at the interface with the lower electrode 2 on the substrate 1 and a particle size of about 3 μm, which is larger than about 1 μm of the CuInSe ₂ thin film obtained from the conventional Cu—In—Se mixed film. was gotten. In addition, lines 21 and 22 in FIG.
CuInSe ₂ thin film 5 obtained by the conventional method containing no Cu
5 shows the open-circuit voltage V _OC and the conversion efficiency E _ff of the solar cell prototyped using FIG. The solar cell using the CuInSe ₂ thin film of this method showed good characteristics with high open-circuit voltage and high conversion efficiency of 12% or more.

[0010] As another method, for a Cu / In laminated film, Se is simultaneously formed at the time of Cu formation, and about 1/100 of the film thickness of Cu.
After stopping the supply of Se in about 2, Cu is formed to a specified thickness, and then
In may be formed. Line 23, 24 in FIG. 2, a solar cell using the CuInSe ₂ thin film thus obtained, simply open the solar cell using the CuInSe ₂ thin film obtained by the conventional method selenide a Cu / In stacked film The voltage and the conversion efficiency are shown in comparison. In addition, AgInSe ₂ is made of CuInS ₂ , AgInS
_The same effect can be obtained when the film _{2 is formed} by a sulfuration method.

[0011]

[Effect of the Invention] I-III containing a group VI element only near the substrate
By heat-treating the element laminated film and the mixed film in an atmosphere containing Se, volume expansion near the substrate can be prevented, and the I-III-VI group ₂ compound is early formed only in the vicinity of the substrate during the temperature rise process. Therefore, generation of the group VI element compound can be suppressed. In addition, since the group VI element is present only in the vicinity of the substrate, the film surface can be grown to a large particle size by a reaction with a gaseous group VI element, for example, Se thermally decomposed from H ₂ Se, thereby increasing the efficiency of the solar cell. Can be improved.

[Brief description of the drawings]

FIG. 1 illustrates a CuInSe ₂ film forming process according to an embodiment of the present invention.
Sectional views shown in the order of (a) to (d)

FIG. 2 shows an example of the present invention and a film formed by a conventional method.
CuInSe comparison diagram of characteristics of the solar cell with _two films

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Lower electrode 3 Cu-In-Se mixed film 4 Cu-In mixed film 5 CuInSe ₂ film

Claims (5)

(57) [Claims] 1. A method for manufacturing a thin-film solar cell having a group I-III-VI chalcopyrite-type ternary compound thin film on a substrate, comprising a group I element, a group III element, and a group VI of the periodic table.
After forming an initial film containing a group III element on the electrode on the substrate, V
Without performing treatment in a Group I element atmosphere,
Forming a mixed film of a group III element and a group III element;
A method for producing a thin-film solar cell, comprising: forming a laminated initial film and a mixed film into an integrated group I-III-VI thin film by treating in a group I element atmosphere. 2. The method according to claim 1, wherein the amount of the group VI element contained in the initial film is equal to or less than the sum of the amount of the group I element and the amount of the group III element. 3. The method according to claim 1, wherein the initial film is a laminated film of each element. 4. The method according to claim 1, wherein the initial film is a mixed film of each element. 5. The method according to claim 1, wherein the substrate temperature at the time of forming the initial film is 400 ° C. or lower.