JP3064658B2 - Solar cell and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar cell using a ZnSe-MnSe solid solution thin film as a light transmitting window layer and a method for manufacturing the same.

[0002]

2. Description of the Related Art High efficiency and low cost of solar cells have become major issues. Above all, thin-film solar cells, which can be easily enlarged, can be significantly reduced in cost, and therefore, it is strongly desired to improve the energy conversion efficiency. As such thin film solar cells, those using compound semiconductor (II-VI or I-III-VI ₂ ) thin films are being widely developed. The structure of a solar cell using a compound semiconductor thin film includes an n-type CdS-based semiconductor layer as a window layer having a wide band gap and transmitting light, and a Cd as an absorption layer having a narrow band gap and absorbing light.
Heterojunction formed by laminating a p-type semiconductor layer, such as Te system or CuInSe ₂ system is used. As a structure, for example, an n-type CdS layer and a p-type CdTe layer are formed on a glass substrate provided with ITO (Indium Tin Oxide) by a vapor deposition method, and finally a metal electrode is provided to obtain a solar cell. Alternatively, screen printing and firing on a glass substrate
A solar cell is obtained by providing a type CdS layer, then a p-type CdTe layer by screen printing and baking, and finally a metal or carbon electrode layer. Instead of CdS, a semiconductor having a wider band gap, such as CdS-ZnS solid solution or ZnSe
It is known that the use of a thin film is very effective in increasing the amount of transmitted light and increasing the conversion efficiency.

[0003]

As described above, the use of the window layer made of a low-resistance semiconductor thin film having a wide band gap is effective for improving the conversion efficiency. However, even in the case of the CdS-ZnS solid solution thin film, the ZnS composition ratio can be improved. Becomes higher, the resistance becomes higher, which may lower the conversion efficiency. It is desired to use a low-resistance n-type semiconductor thin film having a wide band gap.

[0004]

Means for Solving the Problems A structure in which a transparent conductive layer, a window layer of an n-type semiconductor, a light absorbing layer of a p-type semiconductor, and an electrode layer are laminated on a light-transmitting substrate, or a substrate provided with an electrode layer Alternatively, in a solar cell having a configuration in which a light absorbing layer of a p-type semiconductor, a window layer of an n-type semiconductor, and a transparent conductive layer are laminated on a metal substrate having electrode properties, the window layer of the n-type semiconductor has a composition ratio of MnSe. Is mainly composed of a ZnSe-MnSe solid solution of 10 mol% or more.

[0005]

According to the structure of the solar cell of the present invention, the band gap of the ZnSe-MnSe solid solution used as the window layer is wider than that of CdS, so that the amount of light transmitted through the window layer increases, so that the light absorption layer of the p-type semiconductor is increased. As a result, the efficiency of the solar cell is improved. The ZnSe and M of the present invention
According to the simultaneous evaporation by two sources of n, or the simultaneous evaporation of ZnSe and MnSe, or the direct deposition of a solid solution or a mixture of ZnSe and MnSe, a ZnSe-MnSe solid solution thin film having a wide band gap can be formed by an inexpensive evaporation apparatus. It can be easily obtained and is effective for high efficiency.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below.

As shown in FIG. 1, the structure of the solar cell of this embodiment is mainly composed of a transparent conductive layer 2 and a ZnSe-MnSe solid solution having a composition ratio of MnSe of 10 mol% or more on a transparent substrate 1. The window layer 3 of the n-type semiconductor, the light absorbing layer 4 of the p-type semiconductor, and the electrode layer 5 are laminated, and a more desirable composition ratio of MnSe is 50 mol% or more.

As a manufacturing method, ZnSe and Mn are simultaneously deposited on a transparent substrate provided with a transparent conductive layer to form an n-type semiconductor window layer mainly composed of a ZnSe-MnSe solid solution thin film. Forming a light absorbing layer of a p-type semiconductor thereon,
Further, an electrode layer is formed thereon. Alternatively, ZnSe and MnSe may be simultaneously deposited to form an n-type semiconductor window layer mainly composed of a ZnSe-MnSe solid solution thin film. Alternatively, a solid solution or a mixture of ZnSe and MnSe may be deposited to form a window layer of an n-type semiconductor mainly composed of a ZnSe-MnSe solid solution thin film.

Next, this embodiment will be described more specifically. On a glass substrate provided with a transparent conductive layer ITO, Zn
By simultaneous vapor deposition of Se and Mn, the molar ratio of ZnSe to MnSe is 5: 5, and a solid solution film Zn _0.5 Mn _0.5 having a total thickness of 0.5 μm.
Se is formed. In is added to this film. That is, Z
On the n _0.5 Mn _0.5 Se film, 1% of In is vapor-deposited, and N ₂
The mixture is heated at 400 ° C. for 30 minutes in a gas and diffused for effective addition of In. On the n-type semiconductor window layer formed by removing the surface by an etching method of about 100 °, a p-type semiconductor light absorption layer mainly composed of CdTe having a thickness of 5 μm is formed by vapor deposition, and an Au electrode is formed thereon. For comparison, the window layer was changed to the same Zn layer as before.
The characteristics of the solar cell were also examined in the same manner as described above except that 1% of In was added to Se, that is, a ZnSe deposited film.
The characteristics of these solar cells with respect to irradiation light of AM 1.5 (84 mW / cm ² ) are shown in Table 1 (present invention and conventional type).
Also, a solid solution film Zn _{0.2 in which} the molar ratio of ZnSe to MnSe is 2: 8.
A solar cell was formed in the same manner as described above except that Mn _0.8 Se was used. The results are also shown in Table 1 (Invention 2). V _OC (V) is the release voltage, J _SC (mA / cm ² ) is the closing current, η
(%) Indicates the conversion efficiency, and FF indicates the fill factor.

[0010]

[Table 1]

As can be seen from Table 1, the characteristics of the solar cell obtained by the structure of the present invention are far superior to those of the solar cell obtained by the conventional structure. This is because the ZnSe-MnSe solid solution film of the solar cell of the present invention is different from the ZnSe-MnSe solid solution film of the conventional solar cell.
This is because the spectral transmittance is higher than that of the CdS film.

A solar cell having a ZnSe-MnSe solid solution film obtained by simultaneous deposition of ZnSe and Mn has excellent characteristics. The addition of In increases light transmittance and electrical conductivity. Solid solution ZnSe- with other composition ratio of ZnSe and MnSe
Similar effects can be obtained by using MnSe or by using Al or Ga instead of In. This solid solution thin film can be obtained by depositing MnSe by an electron beam method by simultaneous deposition of ZnSe and MnSe, or by depositing a solid solution or a mixture of ZnSe-MnSe by a sputtering method.

Next, a second embodiment of the present invention will be described. As shown in FIG. 2, the composition of the solar cell according to the present embodiment is such that the p-type semiconductor light absorbing layer 7 and the composition ratio of MnSe are 10 mol on a substrate provided with an electrode layer or a metal substrate 6 having electrode properties. % Or more of the n-type semiconductor window layer 8 and the transparent conductive layer 9 mainly composed of a ZnSe-MnSe solid solution, and the composition ratio of MnSe is more preferably 50 mol% or more.

As a manufacturing method, a light absorbing layer of a p-type semiconductor is formed on a substrate provided with an electrode layer or a metal substrate having electrode properties, and ZnSe and Mn are simultaneously deposited thereon to form a ZnSe- An n-type semiconductor window layer mainly composed of a MnSe solid solution thin film is formed, and a transparent conductive layer is further formed thereon. Further, ZnSe and MnSe are simultaneously deposited to form Zn
A window layer of an n-type semiconductor mainly composed of a Se-MnSe solid solution thin film can also be formed. Alternatively, a solid solution or a mixture of ZnSe and MnSe may be deposited to form a window layer of an n-type semiconductor mainly composed of a ZnSe-MnSe solid solution thin film.

Next, this embodiment will be described more specifically. On a glass substrate provided with a Pt electrode layer, a 5 μm-thick p-type semiconductor light absorbing layer mainly composed of CdTe is formed by vapor deposition,
This surface is removed by an etching method of about 100 °, and a solid solution film Zn _0.5 Mn having a molar ratio of ZnSe and MnSe of 5: 5 and a total thickness of 0.5 μm is formed by simultaneous deposition of ZnSe and Mn.
Form _0.5 Se. In is added to this film. That is, 1% of In is vapor-deposited on the Zn _0.5 Mn _0.5 Se film, and heated at 400 ° C. for 30 minutes in N ₂ gas to be diffused and effective addition of In is performed. On the n-type semiconductor window layer thus formed, a transparent electrode layer ITO is formed. For comparison, the characteristics of a solar cell in which 1% of In was added to a conventional ZnSe, that is, a ZnSe vapor deposited film as a window layer, and other than that described above were also examined. AM1.5 (84mW / cm) of these solar cells
^The characteristics for the irradiation light of ² ) are shown in Table 2 (present invention 3 and conventional type). The molar ratio of ZnSe and MnSe is 2: 8 except for using the solid solution film Zn _0.2 Mn _0.8 Se of the also formed solar cell in the same manner described above. The results are also shown in Table 1 (Invention 4). V _OC (V) is the release voltage, J _SC (mA / c
m ² ) is the closing current, η (%) is the conversion efficiency, and FF is the fill factor.

[0016]

[Table 2]

As shown in Table 2, the characteristics of the solar cell obtained by the structure of the present invention are far superior to those of the solar cell obtained by the conventional structure. This is because the ZnSe-MnSe solid solution film of the solar cell of the present invention is different from the ZnSe-MnSe solid solution film of the conventional solar cell.
This is because the spectral transmittance is higher than that of the film.

A solar cell having a ZnSe-MnSe solid solution film obtained by simultaneous deposition of ZnSe and Mn has excellent characteristics. The addition of In increases light transmittance and electrical conductivity. Solid solution ZnSe- with other composition ratio of ZnSe and MnSe
Similar effects can be obtained by using MnSe or by using Al or Ga instead of In. This solid solution thin film can be obtained by depositing MnSe by an electron beam method by simultaneous deposition of ZnSe and MnSe, or by depositing a solid solution or a mixture of ZnSe-MnSe by a sputtering method.

[0019]

According to the present invention, an excellent solar cell having a very high conversion efficiency can be easily obtained. Since this solar cell is formed as a thin film, the cost can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a configuration sectional view of a solar cell according to a first embodiment of the present invention.

FIG. 2 is a configuration sectional view of a solar cell according to a second embodiment of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 translucent substrate 2 transparent conductive layer 3 n-type semiconductor window layer mainly composed of ZnSe-MnSe solid solution 4 p-type semiconductor light absorbing layer 5 electrode layer 6 substrate provided with electrode layer or metal substrate having electrode properties 7 p Type semiconductor light absorption layer 8 n-type semiconductor window layer mainly composed of ZnSe-MnSe solid solution 9 transparent conductive layer

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-63-245963 (JP, A) JP-A-57-26480 (JP, A) Semiconductors and Materials, Chapter 1 (pp. 1-33), W. Giri at et al. , 1988, Academic Press Inc. (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 31/04-31/078

Claims (8)

(57) [Claims] 1. A transparent conductive layer, a window layer of an n-type semiconductor mainly composed of a ZnSe-MnSe solid solution having a composition ratio of MnSe of 10 mol% or more, a light absorbing layer of a p-type semiconductor, and an electrode on a transparent substrate. A solar cell comprising a configuration in which layers are stacked. 2. A light-absorbing layer of a p-type semiconductor on a substrate provided with an electrode layer or a metal substrate having electrode properties, and an n-type mainly composed of a ZnSe-MnSe solid solution having a composition ratio of MnSe of 10 mol% or more. A solar cell comprising a structure in which a window layer of a semiconductor and a transparent conductive layer are laminated. 3. The solar cell according to claim 1, wherein the composition ratio of MnSe is 50 mol% or more. 4. A method according to claim 1, further comprising the step of: forming a Zn layer on the light-transmitting substrate provided with the transparent conductive layer.
A window layer of an n-type semiconductor mainly composed of a ZnSe-MnSe solid solution thin film is formed by a method of simultaneously depositing Se and Mn or ZnSe and MnSe, a light absorbing layer of a p-type semiconductor is further formed thereon, and an electrode is further formed thereon. A method for manufacturing a solar cell, comprising forming a layer. 5. A light absorbing layer of a p-type semiconductor is formed on a substrate provided with an electrode layer or a metal substrate having electrode properties, and ZnSe and Mn, or ZnSe and MnSe are simultaneously deposited thereon to form a ZnSe. -MnSe solid solution thin film n
A method for manufacturing a solar cell, comprising forming a window layer of a mold semiconductor, and further forming a transparent conductive layer thereon. 6. A method for manufacturing a semiconductor device, comprising the steps of: forming a Zn film on a transparent substrate provided with a transparent conductive layer;
A solid solution or a mixture of Se and MnSe is deposited and ZnSe-
A method for manufacturing a solar cell, comprising: forming a window layer of an n-type semiconductor mainly composed of a MnSe solid solution thin film, forming a light absorbing layer of a p-type semiconductor thereon, and forming an electrode layer thereon. 7. A p-type semiconductor light absorbing layer is formed on a substrate provided with an electrode layer or a metal substrate having electrode properties, and a solid solution or a mixture of ZnSe and MnSe is deposited thereon to form ZnSe-MnSe. A method for manufacturing a solar cell, comprising forming an n-type semiconductor window layer mainly composed of a solid solution thin film, and further forming a transparent conductive layer thereon. 8. In the ZnSe-MnSe solid solution thin film, In, G
8. A method according to claim 4, wherein a or Al is added.
A method for manufacturing the solar cell according to the above.