JP2003078151A - Thin film solar cell - Google Patents

Abstract

(57) Abstract: Even if fluorescence is randomly emitted using a transparent substrate having fluorescence characteristics, the power generation efficiency can be increased by effectively utilizing the randomly emitted fluorescence. To provide thin-film solar cells. SOLUTION: Incident light 10 is focused on a circular pinhole group 9 of a second reflection layer 8 by a hemispherical lens group 11. The light incident from the group of circular pinholes 9 through the transparent substrate 1 having the fluorescent property and the light radiated and scattered by the transparent substrate 1 having the fluorescent property and converted into light in a wavelength range usable for photoelectric conversion. Light is multiply reflected between the first reflection layer 7, the second reflection layer 8, and the photoelectric conversion layer 5. Therefore, light in the wavelength range where photoelectric conversion can be performed is generated by the photoelectric conversion layer 5.
And the power generation efficiency is increased.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a thin film solar cell.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 10, a thin film solar cell includes a comb-shaped collector electrode 102 made of Al or Ag having high conductivity and an S-type collector electrode 102 on a transparent insulating substrate 101 such as glass.
A transparent conductive film 103 made of nO ₂ , ITO, ZnO, or the like is formed, and a-Si: H or a-SiG is formed thereon.
a p-layer 104, which is a p-type impurity-doped semiconductor layer, made of an amorphous semiconductor such as e: H or a-SiC: H.
A photoelectric conversion layer 107 is formed by stacking an i layer 105 which is an intrinsic semiconductor and an n layer 106 which is an n-type impurity doped layer in this order, and a transparent conductive film for effectively utilizing reflected light from the back surface on the photoelectric conversion layer 107. 108, Al and A having a relatively high reflectance
The back electrode 109 made of g is laminated.

In order to improve power generation efficiency, a tandem structure thin film solar cell has been proposed as shown in FIG. The tandem structure thin-film solar cell has a p-layer 104 and an i-layer 1.
05, the photoelectric conversion layers 107, 107, 107 having different band gaps and composed of the n-layer 106 are laminated, and photoelectric conversion of light having different wavelengths is performed in each photoelectric conversion layer 107 to thereby obtain a total open circuit voltage. To increase the power generation efficiency.

Further, for the purpose of further improving the power generation efficiency of such a thin-film solar cell, as shown in FIG. 12, a transparent substrate 111 having a fluorescent property mixed with fluorescent particles or phosphorescent fluorescent particles 110 is used. Photoelectric conversion layer 10
7, a study is underway to convert light of a wavelength that does not contribute to photoelectric conversion of incident light 112 into light 113 of a wavelength that contributes to photoelectric conversion.

[0005]

In the solar cell using the transparent substrate 111 having the fluorescent property shown in FIG. 12, the contained fluorescent particles or the phosphorescent fluorescent particles 110 contribute to the photoelectric conversion contained in the incident light 112. Light having a wavelength that contributes to photoelectric conversion contained in the incident light 112 is scattered by the scattered light 114.
Becomes This scattered light 114 does not reach the photoelectric conversion layer 107, and the amount of light 115 having a wavelength that contributes to photoelectric conversion is reduced, so that expected improvement in power generation efficiency cannot be realized. In addition, the fluorescent particles or the phosphorescent fluorescent particles 1 contained therein
Light having a wavelength that contributes to photoelectric conversion converted by 10
The direction in which 3 is emitted is random, and approximately half of the light having a wavelength that contributes to photoelectric conversion is emitted in the direction opposite to the photoelectric conversion layer 107, which does not lead to improvement in power generation efficiency.

Although not shown, even in the case of using a fluorescent glass that does not use a particulate fluorescent material, the direction in which fluorescence is emitted becomes random, and similarly, about half of the light having a wavelength that contributes to photoelectric conversion is It is emitted in the direction opposite to the photoelectric conversion layer, which does not lead to improvement in power generation efficiency.

In such a situation, in any of the solar cells shown in FIGS. 10 and 11, a transparent substrate 111 having a fluorescent characteristic shown in FIG. 12 is used instead of the transparent insulating substrate 101 such as glass. It occurs when there is.

[0008] Therefore, an object of the present invention is to use a transparent substrate having a fluorescent property and to emit fluorescent light randomly.
An object of the present invention is to provide a thin-film solar cell capable of enhancing power generation efficiency by effectively utilizing this randomly emitted fluorescence.

[0009]

In order to solve the above problems, a thin film solar cell of the present invention comprises a transparent substrate having fluorescent characteristics, a photoelectric conversion layer located on one surface side of the transparent substrate, and It is characterized in that it is provided on the other surface of the transparent substrate and is provided with a reflecting layer having a group of light transmitting holes and a condenser lens group for condensing incident light into the group of light transmitting holes.

According to the above construction, the incident light is condensed by the condenser lens group in the light transmitting hole of the reflecting layer. Then, the light incident through the transparent substrate having the fluorescent property from the light transmission hole, and the light emitted by the transparent substrate having the fluorescent property, scattered and converted into light in the wavelength range that can be used for photoelectric conversion, Multiple reflection occurs between the photoelectric conversion layer and the reflective layer. Therefore, the point where the incident light is efficiently condensed to the light transmitting hole by the condensing lens, and the light in the wavelength range that cannot be used for photoelectric conversion by the transparent substrate having the fluorescent property becomes the light in the wavelength range that can be used for photoelectric conversion. By the synergistic effect of the point to be converted and the point that light in the wavelength range available for this photoelectric conversion is multiply reflected between the photoelectric conversion layer and the reflective layer, it contributes to the photoelectric conversion applied to the photoelectric conversion layer. The amount of light in the wavelength range is remarkably increased, and the power generation efficiency can be made extremely high.

In one embodiment, the transparent substrate having the above-mentioned fluorescent property is a transparent substrate in which fluorescent particles or phosphorescent fluorescent particles are dispersed.

In the above-mentioned embodiment, since the fluorescent particles or the phosphorescent fluorescent particles are dispersed on the transparent substrate, it is possible to easily
The transparent substrate can have fluorescent properties. In particular, when using phosphorescent fluorescent particles, the energy of light is stored,
After that, since fluorescence is emitted, power can be generated even at night when the thin film solar cell is not irradiated with light.

In one embodiment, the condenser lens is a hemispherical lens, the light transmission hole is a circular pinhole, and the condensing position of the hemispherical lens is the circle provided on the reflection layer. Make sure that the center of the shape pinhole matches
The hemispherical lens group is mounted on the reflective layer.

According to the above-mentioned embodiment, the hemispherical lens group is mounted on the reflective layer so that the condensing position of the hemispherical lens substantially coincides with the center of the circular pinhole of the reflective layer. Therefore, the incident light is efficiently focused on the center of the circular pinhole by the hemispherical lens. Therefore, power generation efficiency can be increased.

In one embodiment, the condenser lens is a cylindrical lens, the light transmission hole is a linear slit, and the condensing position of the cylindrical lens is the linear shape provided on the reflection layer. The cylindrical lens group is mounted on the reflective layer so as to substantially coincide with the center line of the slit.

According to the above-mentioned embodiment, the cylindrical lens group is mounted on the reflective layer so that the condensing position of the cylindrical lens substantially coincides with the center line of the linear slit of the reflective layer. Therefore, the incident light is efficiently condensed on the center line of the linear slit by the cylindrical lens. Therefore,
Power generation efficiency can be increased.

In one embodiment, a reflective layer is provided on the opposite side of the photoelectric conversion layer from the transparent substrate side.

According to the above-described embodiment, the light which is condensed by the condenser lens group and passes through the light transmission hole of the reflection layer and the transparent substrate, and the wavelength range which can be used for photoelectric conversion by the transparent substrate having the fluorescent property. The light converted into the light is multiple-reflected between the reflection layer provided on the transparent substrate and the reflection layer on the side opposite to the transparent substrate side of the photoelectric conversion layer. Therefore, the amount of light in the wavelength region that contributes to photoelectric conversion applied to the photoelectric conversion layer is significantly increased, and the power generation efficiency can be extremely increased.

In one embodiment, the condenser lens is made of an ultraviolet curable resin.

In the above-described embodiment, since the condenser lens is made of the ultraviolet curable resin, the 2P method (photopolymerization method: Photo) is used.
It is possible to collectively form the condenser lens group by a simple method such as Polymerization), and it is possible to realize the cost reduction of the thin film solar cell.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a thin film solar cell according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a schematic cross-sectional view of the thin-film solar cell of this embodiment.

In the thin film solar cell, the comb-shaped collector electrode 3, the transparent conductive film 4, the photoelectric conversion layer 5, the transparent conductive film are formed on one surface of the transparent substrate 1 in which the fluorescent particles or the phosphorescent fluorescent particles 2 are dispersed. 6 and the first reflective layer 7 are sequentially laminated. Further, on the other surface of the transparent substrate 1, a second reflective layer 8 having a circular pinhole group 9 as an example of a light transmitting hole group, and an incident light 10 is collected in the circular pinhole group 9. A hemispherical lens group 11 is formed as an example of a condenser lens group arranged to emit light.

The center of each hemispherical lens 11 of the hemispherical lens group 11 is made to substantially overlap with the center of the circular pinhole 9 of the circular pinhole group 9 of the second reflecting layer 8, and this hemisphere is formed. The incident light is efficiently condensed on the circular pinhole 9 of the second reflective layer 8 by the lens 11.

Further, in the hemispherical lens group 11, as shown in FIG. 2, hemispherical lenses 11, 11, 11 ,. That is, the hemispherical lens group 11 includes a plurality of hemispherical lenses 11 arranged in the lateral direction.
Is a hemispherical lens 1 in the upper and lower rows that are adjacent to each other.
The arrangement pitch of 1 is shifted by a half pitch, and has an arrangement structure in a close-packed state in which six hemispherical lenses 11 are in contact with each one hemispherical lens 11. Thus, the reflection area 14
To minimize light utilization efficiency and increase power generation efficiency.

When the thin-film solar cell shown in FIG. 1 is irradiated with light such as sunlight, incident light 10 is transmitted through a hemispherical lens group 11 to a circular pinhole group 9 formed on the second reflective layer 8. The light is condensed to the transparent substrate 1, the transparent conductive film 4, the photoelectric conversion layer 5, and the transparent conductive film 6 in which the fluorescent particles or the phosphorescent fluorescent particles 2 are dispersed, and is reflected by the first reflective layer 7. . The light reflected by the first reflective layer 7 passes through the transparent conductive film 6, enters the photoelectric conversion layer 5 again, and is transmitted. The transmitted light passes through the transparent conductive film 4, is reflected by the second reflective layer 8, and enters the photoelectric conversion layer 5 again. In addition, the light reflected by the photoelectric conversion layer 5 also becomes
The light is reflected by the reflective layer 8 and is incident on the photoelectric conversion layer 5 again. In this way, the light incident from the circular pinhole group 9 is multiply reflected between the first reflective layer 7, the second reflective layer 8, and the photoelectric conversion layer 5, so that the incident light 1
The photoelectric conversion layer 5 is efficiently irradiated with 0, and the photoelectric conversion layer 5
The power generation efficiency can be increased. Similarly, the light reflected by the comb-shaped current collecting electrode 3 is also reflected by the second reflective layer 8 and is incident on the photoelectric conversion layer 5 again, so that the power generation efficiency can be increased.

In the present embodiment, the fluorescent particles or the phosphorescent fluorescent particles 2 dispersed in the transparent substrate 1 convert light in a wavelength range not used for photoelectric conversion into light in a wavelength range available for photoelectric conversion. As a result, the power generation efficiency can be further increased.

For example, a pin made of an amorphous Si semiconductor
When the photoelectric conversion layer 5 is configured by bonding, the wavelength range of light used for photoelectric conversion (hereinafter, referred to as photosensitive wavelength range) is
The wavelength is 450 to 650 nm, and light outside the photosensitive wavelength range is consumed as heat without being used for photoelectric conversion.

Here, as shown in FIG. 1, when the fluorescent particles or the phosphorescent fluorescent particles 2 are dispersed in the transparent substrate 1,
Light having a wavelength other than the photosensitive wavelength range is absorbed by the fluorescent particles or the phosphorescent fluorescent particles 2 and the light in the photosensitive wavelength range is emitted from the fluorescent particles or the phosphorescent fluorescent particles 2. The light of the wavelength is converted into the light of the photosensitive wavelength range, and the power generation efficiency can be improved.

For example, Y ₂ O ₂ S having a particle size of 5 to 20 μm:
By using the phosphorescent fluorescent particles of Eu, Mg, and Ti, light having a wavelength of 200 to 450 nm is absorbed to obtain 625
It is possible to emit light with a wavelength of nm. Also,
By using oxyfluoride-based crystallized glass containing Er ³⁺ ions, it is possible to absorb light having a wavelength near 800 nm and emit light having a wavelength of 550 to 660 nm.

As fluorescent materials other than the above, compounds containing strontium oxide and aluminum oxide are added to the rare earth elements europium (Eu) and dysprosium (D).
y) added SrAl ₂ O ₄ : Eu, Dy and Sr ₄
Al ₁₄ O ₂₅ : Eu, Dy and CaAl ₂ O ₄ : E
It is possible to use fluorescent materials such as u, Dy and ZnS: Cu.

In a conventional thin-film solar cell, as shown in FIG. 12, scattered light 112 scattered by fluorescent particles or phosphorescent fluorescent particles 110 and light emitted from fluorescent particles or phosphorescent fluorescent particles 110. Part of 113
Although it did not enter the photoelectric conversion layer 107, which caused a decrease in power generation efficiency, according to the present embodiment shown in FIG. 1, the scattered light 12 scattered by the fluorescent particles or the phosphorescent fluorescent particles 2 is used. , And fluorescent particles or phosphorescent fluorescent particles 2
The light 13 emitted from is reflected by the second reflective layer 8 and enters the photoelectric conversion layer 5. In this way, the scattered light 12 and the emitted light 13 are multiply reflected by the first reflective layer 7, the photoelectric conversion layer 5, and the second reflective layer 8,
High power generation efficiency can be realized.

Further, in the thin-film solar cell of this embodiment, as shown in FIG. 2, since the hemispherical lens group 11 is arranged on the transparent substrate 1 so as to be in a close-packed state, the incident light 10 is The area 14 reflected by the reflective layer 8 is minimized, and the power generation efficiency is increased.

Although the power generation efficiency is low, the hemispherical lenses (not shown) are regularly arranged vertically and horizontally in the same phase, and four hemispherical lenses are in contact with one hemispherical lens. You may make it a physical arrangement structure.

[0035]

Example 1 A thin film solar cell according to the embodiment shown in FIG. 1 was produced according to the process shown in FIGS.

First, as shown in FIG. 3, a comb-shaped collector electrode 3 was formed on a glass substrate 1 made of fluorescent glass (Lumirus G9) manufactured by Sumita Optical Glass Co., Ltd., and then the film thickness was 30 nm.
Of SnO ₂ transparent conductive layer 4 was formed by reactive sputtering. Here, Lumiras G9 is 200-400n
It is a fluorescent glass that absorbs light having a wavelength of m and emits light having a wavelength of 540 nm.

Next, p, which is a p-type impurity-doped semiconductor layer, is formed.
Layer, i layer that is an intrinsic semiconductor, and n-type impurity-doped layer
The photoelectric conversion layer 5 formed by stacking n layers in this order is SnO._Two
Plasma CVD (chemical vapor deposition) device on the transparent conductive layer 4
Formed by chemical vapor deposition. Each semiconductor layer is
SiH respectively_FourGas / H_TwoGas / CH_FourGas B _Two
H₆Film thickness of 15 nm grown by vapor phase growth using mixed gas of gases
A-SiC: H p-layer, SiH_FourGas / H_TwoGas mixture
Vapor-grown a-S with a thickness of 200 nm
i: i layer of H, SiH_FourGas / H_TwoGas / PH_ThreeOf gas
Vapor-grown a-S with a film thickness of 15 nm using mixed gas
i: H n layer. After forming the photoelectric conversion layer 5,
SnO with a film thickness of 30 nm_TwoReactive sputtering of transparent conductive layer 6
It is formed by a ring and is made of Al with a thickness of 100 nm.
A first reflective layer 7 consisting of
It was Here, the first reflective layer 7 also serves as a collector electrode.
Be done.

Next, as shown in FIG. 4, the first reflective layer 7
A Ta protective film 15 having a film thickness of 20 nm is formed thereon by sputtering, and the Ta protective film 15 is formed on the other surface of the fluorescent glass substrate 1 with a film thickness of 1 nm.
The second reflective layer 8 made of Al having a thickness of 00 nm is formed by sputtering.

Next, as shown in FIG. 5, the second reflective layer 8 is wet-etched with diluted nitric acid using a photoresist mask (not shown). A circular pinhole group 9 is formed. The diameter of the formed pinhole 9 was 0.5 mm.

Next, as shown in FIG. 6, a transparent glass stamper 1 having a recess 16 corresponding to a hemispherical lens group is formed.
7 is filled with the uncured ultraviolet curable resin 18, and the condensing position of each hemispherical lens 11 and the circular pinhole 9
7, the transparent glass stamper 17 and the fluorescent glass substrate 1 are brought into close contact with each other, and the ultraviolet curable resin 18 is irradiated with the ultraviolet light 19 through the transparent glass stamper 17. Then, after curing the ultraviolet curable resin 18, the transparent glass stamper 17 is peeled off, so that the hemispherical lens group 11 is easily formed at once. Thus, the thin film solar cell is completed. The hemispherical lens 11 of the thin-film solar cell of Example 1 manufactured here is shown in FIG.
As shown in FIG. 7, the condenser lens group 9 is arranged in the closest packed state. The diameter of the hemispherical lens 11 is 10 mm.
The lens surface was spherical with the center position of the pinhole 9 as the center.

For comparison, a conventional thin film solar cell shown in FIG. 12 was similarly prepared as Comparative Example 1. Here, SnO is used to maximize the photoelectric conversion efficiency in the conventional thin film solar cell due to the antireflection effect of the transparent conductive layer 2.
₂ The film thickness of the transparent conductive layer was 100 nm.

For the thin film solar cell of Example 1 and the thin film solar cell of Comparative Example 1 produced according to the above method, AM
When the IV characteristic was measured by irradiating light of 100 mW / cm ^{2 with} a 1.5 simulator, the thin film solar cell of Example 1 had an open circuit voltage of about 25% as compared with the thin film solar cell of Comparative Example 1. It was confirmed that the short circuit current was about 9% larger. Therefore, it was found that the thin film solar cell of Example 1 had a photoelectric conversion efficiency of about 36% higher than that of the thin film solar cell of Comparative Example 1.

[0043]

[Example 2] The thin-film solar cell of Example 2 was used as a transparent substrate in transparent glass with a particle size of 10μ manufactured by Nemoto Special Glass Co., Ltd.
The phosphorescent glass in which m of the phosphorescent fluorescent particles (G300) was dispersed at a weight ratio of 20% was used. Then, in the same manner as in Example 1, the thin-film solar cell of Example 2 was created.

Further, in the structure of the conventional thin film solar cell shown in FIG. 12, a thin film solar cell using a transparent substrate made of phosphorescent glass of Example 2 was manufactured as Comparative Example 2.

For the thin film solar cell of Example 2 and the thin film solar cell of Comparative Example 2 produced according to the above method, AM
When the IV characteristics were measured by irradiating light of 100 mW / cm ^{2 with} a 1.5 simulator, the thin film solar cell of Example 2 had an open circuit voltage of about 55% as compared with the thin film solar cell of Comparative Example 2. It was confirmed that the short circuit current was about 25% larger. Therefore, it was found that the thin film solar cell of Example 2 had a photoelectric conversion efficiency of about 94% higher than that of the thin film solar cell of Comparative Example 2.

Further, since the phosphorescent fluorescent particles are used,
Even after the light irradiation by the AM1.5 simulator is stopped, the light emitted from the phosphorescent fluorescent particles causes 1
Power generation could be continued with a power generation efficiency of about 0%.

[0047]

Third Embodiment FIG. 8 shows a thin film solar cell having a tandem structure according to a third embodiment.

In the case of this tandem thin film solar cell,
A plurality of photoelectric conversion layers 5 each having a pin junction in FIG. 1 are laminated, and in FIG.
Three layers are formed: a first photoelectric conversion layer 51 having a junction, a second photoelectric conversion layer 52 having a pin junction, and a third photoelectric conversion layer 53 having a pin junction. Like this, 3
In the case where the photoelectric conversion layers 51, 52, and 53 of the layers are stacked to form the photoelectric conversion layer having the tandem structure, the first reflective layer 7, the second reflective layer 8, and the second reflective layer 8 are formed as in the case of FIG. Between the photoelectric conversion layers 51, 52, 53, the light incident from the pinhole group 9 and the scattered light 12 and the emitted light 13 from the fluorescent particles or the phosphorescent fluorescent particles 2 are multiply reflected, whereby the incident light 10 And scattered light 12 and emitted light 13 are photoelectric conversion layers 51,
The photoelectric conversion layers 51 and 5 are efficiently irradiated to the 52 and 53.
The power generation efficiency of 2, 53 can be increased. Further, since the photoelectric conversion layers 51, 52, 53 are connected in series, the open circuit voltage between the terminals is increased, and the power generation efficiency can be further increased. Further, the band gaps of the respective photoelectric conversion layers 51, 52, 53 are made different,
The wavelength of light absorbed for photoelectric conversion in each photoelectric conversion layer 51, 52, 53 can be shifted so that light over a wide wavelength range can be used for photoelectric conversion more efficiently, and power generation efficiency can be increased. You can

In Example 3, photoelectric conversion layers 51, 5
Other than 2, 53, it was formed in the same manner as in the first embodiment.

The photoelectric conversion layers 51, 52 and 53 are respectively composed of SiH ₄ gas / H ₂ gas / CH ₄ gas / B ₂ H ₆
A film with a film thickness of 10 nm obtained by vapor phase growth using a mixed gas of gases
-SiC: p layer of the H, the SiH ₄ gas · _H vapor grown film thickness 60nm with ₂ gas mixed gas of a-Si: i layer of H, the SiH ₄ gas · _{H 2} gas · PH ₃ gas N of a-Si: H with a film thickness of 10 nm that was vapor-grown using a mixed gas
It has a pin structure composed of layers and was formed by repeatedly performing vapor phase growth by plasma CVD.

For the thin film solar cell of Example 3 having a tandem structure and the thin film solar cell of Example 1 above, AM1.
Irradiate 100 mW / cm ² of light with 5 simulators,
When the IV characteristics were measured, the thin film solar cell of Example 3 had an open circuit voltage of 68 compared to the thin film solar cell of Example 1.
%, And the short-circuit current was reduced by about 19%. That is, it was found that the thin film solar cell of Example 3 had a photoelectric conversion efficiency of about 36% higher than that of the thin film solar cell of Example 1.

In Example 3, photoelectric conversion layers 51, 5
2 and 53 are formed under the same conditions, respectively, but the film thickness of each photoelectric conversion layer is optimized, and further, the type of semiconductor of each photoelectric conversion layer is changed to use light for photoelectric conversion. By shifting the wavelength of, it is possible to realize a higher photoelectric conversion efficiency.

[0053]

Fourth Embodiment FIG. 9 shows a perspective sectional view of a thin film solar cell according to a fourth embodiment. 9, the same components as those of the thin-film solar cell of Example 1 of FIG. 1 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the first embodiment shown in FIG. 1, the condensing function has the second reflecting layer 8 having the circular pinhole group 9 formed on the transparent substrate 1 and the incident light on the circular pinhole group 9. The thin film solar cell according to the fourth embodiment has a condensing function formed on the transparent substrate 1 and is parallel and evenly spaced. A second reflective layer 21 having a light transmitting slit group 20 composed of a plurality of linear slits 20 arranged in parallel with each other, and a cylindrical lens arranged to condense the incident light 10 on the center line of the linear slit group 20. And the group 22.

Also in this case, as in the first embodiment, the light condensed by the cylindrical lens group 22 and incident from the linear slit group 20 and the fluorescent particles or the phosphorescent fluorescent particles 2 in the transparent substrate 1 (see FIG. Scattered light 12)
(Refer to FIG. 1) and emitted light 13 (see FIG. 1) are multiply reflected between the first reflective layer 7, the second reflective layer 21, and the photoelectric conversion layer 5, so that the incident light 10 and the scattered light are scattered. 12 and synchrotron radiation 1
3 is efficiently irradiated to the photoelectric conversion layer 5, and the photoelectric conversion layer 5
The power generation efficiency can be increased.

The thin film solar cell of Example 3 was manufactured in the same manner as the process of Example 1 shown in FIGS. That is, the second reflective layer 21 is formed on the transparent substrate 8, and a plurality of linear light transmission slit groups 20 having a width of 0.5 mm and arranged in parallel and at equal intervals are formed on the second reflective layer 21. did. Then, a cylindrical lens group 22 arranged to collect the incident light 10 on the light transmission slit group 20 was formed on the second reflective layer 21. The cross-sectional shape of this cylindrical lens 22 was semicircular, and its diameter was 10 mm.

For the thin-film solar cell of Example 4 and the thin-film solar cell of Comparative Example 1, 1 with an AM1.5 simulator.
When the IV characteristics were measured by irradiating with light of 00 mW / cm ² , the thin film solar cell of Example 4 had an open circuit voltage of about 28% higher than that of the thin film solar cell of Comparative Example 1 and a short circuit current. It was confirmed that it was about 10% larger. Therefore, it was found that the thin film solar cell of Example 4 had a photoelectric conversion efficiency of about 39% higher than that of the thin film solar cell of Comparative Example 1.

[0058]

As is apparent from the above, according to the thin film solar cell of the present invention, the light is condensed in the light transmitting hole of the reflecting layer by the condenser lens group and is incident through the transparent substrate having the fluorescent property. The light and the light that is emitted and scattered by the transparent substrate having the fluorescent property and converted into the light in the wavelength range that can be used for photoelectric conversion are multiply reflected between the photoelectric conversion layer and the reflective layer. Therefore, according to the thin-film solar cell of the present invention, the point where the incident light is efficiently condensed to the light transmitting hole by the condenser lens, and the light in the wavelength range that cannot be used for photoelectric conversion due to the transparent substrate having the fluorescent property is generated. Due to the synergistic effect of the point of being converted into light in the wavelength range available for photoelectric conversion and the point of multiple reflection of light in the wavelength range available for photoelectric conversion between the photoelectric conversion layer and the reflecting layer, The light amount of the light in the wavelength range that contributes to the photoelectric conversion applied to the conversion layer is significantly increased, and the power generation efficiency can be made extremely high.

In one embodiment, since the fluorescent particles or the phosphorescent fluorescent particles are dispersed in the transparent substrate, the transparent substrate can easily have the fluorescent characteristic. In particular, when the phosphorescent fluorescent particles are used, the energy of light is stored and the fluorescence is emitted later, so that power generation can be performed even at night when the thin film solar cell is not irradiated with light.

In one embodiment, the hemispherical lens group is mounted on the reflective layer so that the condensing position of the hemispherical lens substantially coincides with the center of the circular pinhole of the reflective layer. With the hemispherical lens, incident light can be efficiently focused on the center of the circular pinhole to increase power generation efficiency.

In one embodiment, the cylindrical lens group is mounted on the reflective layer so that the condensing position of the cylindrical lens substantially coincides with the center line of the linear slit of the reflective layer. With the cylindrical lens, incident light can be efficiently focused on the center line of the linear slit, and the power generation efficiency can be increased.

In one embodiment, the light condensed by the condensing lens group and passing through the transparent substrate through the light transmitting holes of the reflective layer and the wavelength range available for photoelectric conversion by the transparent substrate having the fluorescent property are provided. Since the light converted into light is multiply reflected between the reflective layer provided on the transparent substrate and the reflective layer on the opposite side of the transparent substrate side of the photoelectric conversion layer, the photoelectric conversion layer is irradiated with the light. The amount of light in the wavelength range that contributes to the photoelectric conversion is significantly increased, and the power generation efficiency can be made extremely high.

In one embodiment, since the condenser lens is made of an ultraviolet curable resin, the 2P method (photopolymerization method: Photo Polymer) is used.
It is possible to collectively form the condenser lens group by a simple method such as rization), and it is possible to reduce the cost of the thin-film solar cell.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a thin film solar cell of the present invention.

FIG. 2 is a plan view of a thin film solar cell of the present invention.

FIG. 3 is a cross-sectional view illustrating a method for manufacturing a thin film solar cell of the present invention.

FIG. 4 is a cross-sectional view illustrating a method of manufacturing a thin film solar cell of the present invention.

FIG. 5 is a cross-sectional view illustrating a method for manufacturing a thin film solar cell of the present invention.

FIG. 6 is a cross-sectional view illustrating a method for manufacturing a thin film solar cell of the present invention.

FIG. 7 is a cross-sectional view illustrating a method for manufacturing a thin film solar cell of the present invention.

FIG. 8 is a cross-sectional view of a thin film solar cell of the present invention.

FIG. 9 is a cross-sectional perspective view of the thin film solar cell of the present invention.

FIG. 10 is a cross-sectional view of a conventional thin film solar cell.

FIG. 11 is a cross-sectional view of a conventional thin film solar cell.

FIG. 12 is a cross-sectional view of a conventional thin film solar cell.

[Explanation of symbols]

1 transparent substrate 2 Fluorescent particles or phosphorescent fluorescent particles 3 Comb type collector electrode 4 Transparent conductive film 5 Photoelectric conversion layer 6 Transparent conductive film 7 First reflective layer 8 Second reflective layer 9 Light transmission hole 10 incident light 11 Condensing lens group 12 scattered light 13 Synchrotron radiation

Claims (6)

[Claims] 1. A transparent substrate having a fluorescent property, a photoelectric conversion layer located on one surface side of the transparent substrate, and a reflective layer provided on the other surface of the transparent substrate and having a group of light transmission holes. A thin-film solar cell comprising: the light-transmitting hole group and a condenser lens group that condenses incident light. 2. The thin film solar cell according to claim 1, wherein the transparent substrate having the fluorescent property is a transparent substrate in which fluorescent particles or phosphorescent fluorescent particles are dispersed. 3. The thin-film solar cell according to claim 1, wherein the condenser lens is a hemispherical lens, the light transmission hole is a circular pinhole, and the condensing position of the hemispherical lens is The thin-film solar cell, wherein the hemispherical lens group is mounted on the reflective layer so as to substantially coincide with the center of the circular pinhole provided in the reflective layer. 4. The thin-film solar cell according to claim 1, wherein the condenser lens is a cylindrical lens, the light transmitting hole is a linear slit, and the condensing position of the cylindrical lens is the slit. A thin-film solar cell in which the cylindrical lens group is mounted on the reflective layer so as to substantially coincide with the center line of the linear slit provided in the reflective layer. 5. The thin film solar cell according to claim 1, wherein a reflective layer is provided on the side of the photoelectric conversion layer opposite to the transparent substrate side. . 6. The thin-film solar cell according to claim 1, wherein the condenser lens is made of an ultraviolet curable resin.