JP2003078156A - Thin film solar battery and light converging/reflecting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin film solar battery capable of raising a power generating efficiency by effectively utilizing a fluorescence radiated at random even when the fluorescence is radiated at random, and to provide a light converging/ reflecting element. SOLUTION: An incident light 14 is converged to a circular pinhole group 12 of a reflection layer 11 by a hemispherical light converging lens group 13 of the light converging/reflecting element 100. The light incident from the group 12 is converted into alight of a wavelength region capable of being photoelectrically converted through a transparent substrate 10 having fluorescent characteristics. This light is multiple-reflected between a reflection layer 2 of the element 100 and the layer 11 of the light converging/reflecting element 200. Accordingly, a light quantity irradiated to a photoelectric conversion layer 6 is increased to raise a power generating efficiency.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, as a thin film solar cell, a thin film polycrystalline Si solar cell which performs photoelectric conversion by a pn junction, or a pi
There is an amorphous Si solar cell that performs photoelectric conversion by n-junction.

In the thin film polycrystalline Si solar cell, as shown in FIG. 14, an electrode metal layer 142 having a light reflecting effect and a single conductive type impurity are highly doped on a substrate 141 which also serves as a support. Polycrystalline Si thin film semiconductor layer 14
3, a polycrystalline Si thin film semiconductor layer 144 slightly doped with the same conductivity type impurities as the polycrystalline Si thin film semiconductor layer 143, the polycrystalline Si thin film semiconductor layers 143, 144
A polycrystalline Si thin film semiconductor layer 145 doped with an impurity of a conductivity type opposite to that of the above, a current collecting electrode 146 for taking out an electric current, and an antireflection layer 147 for taking in light efficiently. There is. The polycrystalline Si thin film semiconductor layer 143 doped with the impurities at a high concentration serves to improve the electrical connection between the electrode metal layer 142 and the polycrystalline Si thin film semiconductor layer 144 slightly doped with the impurities.

The amorphous Si solar cell shown in FIG.
As shown in FIG. 3, an electrode metal layer 152 having a light reflection effect, an n layer 153 made of an amorphous semiconductor doped with an n-type impurity, and an intrinsic semiconductor made of an amorphous semiconductor are formed on a substrate 151 which also serves as a support. I layer 154, a p layer 155 made of an amorphous semiconductor doped with a p-type impurity, a collector electrode 156 for taking out a current, and an antireflection layer 157 for taking in light efficiently. Has been done.

In order to improve power generation efficiency, a tandem structure thin film solar cell in which a pn junction made of a polycrystalline semiconductor shown in FIG. 14 and a pin junction made of an amorphous semiconductor shown in FIG. 15 are laminated is proposed. ing.

Further, for the purpose of further improving the power generation efficiency of such a thin film solar cell, as shown in FIG. 16, a transparent material 161 having a fluorescent property is disposed on the light incident side of the solar cell shown in FIG. However, in the pin junction, studies are underway to convert light having a wavelength that does not contribute to photoelectric conversion into light 165 that has a wavelength that contributes to photoelectric conversion.

[0007]

In the thin film solar cell shown in FIGS. 14 and 15, the antireflection layers 147 and 157 are provided on the light incident surface for the purpose of suppressing surface reflection as much as possible. It is difficult to set to zero. Further, the antireflection layers 147 and 157 generally have wavelength dependence, and there is a problem that surface reflection increases due to deviation of the light wavelength from the design wavelength center. In a tandem structure thin-film solar cell that uses light of a relatively wide wavelength for photoelectric conversion, the adverse effect is
It will be even bigger. For example, a pn junction made of a polycrystalline Si semiconductor has a wavelength of 450 to 1000 n.
m light is used for photoelectric conversion, and in a pin junction made of an amorphous Si semiconductor, light having a wavelength of 450 to 700 nm is used for photoelectric conversion. Further, in order to extract the electric current, the collector electrodes 146 and 156 provided on the light incident side are
This will surely bring about a decrease in power generation efficiency.

Further, the polycrystalline Si semiconductor layer 144 which absorbs light to generate electric charge and generates electric power needs to have a sufficient film thickness to absorb incident light. The mileage increases, and the current that can be extracted to the outside decreases. In addition, the polycrystalline Si semiconductor layer 144
The increase in the film thickness of (3) leads to an increase in manufacturing time and an increase in the amount of material used, which makes cost reduction difficult.

Further, as shown in FIG. 16, a transparent glass substrate in which fluorescent particles or phosphorescent fluorescent particles 162 are dispersed can be used as the transparent material 161 having fluorescent characteristics. The fluorescent particles or the phosphorescent fluorescent particles 162 are
When the light having a wavelength that contributes to photoelectric conversion included in the incident light 163 is not transmissive, the light having a wavelength that contributes to photoelectric conversion included in the incident light 163 is scattered and scattered light 1
64. This scattered light 164 does not reach the pin junction, the amount of light 166 having a wavelength that contributes to photoelectric conversion is reduced, and the expected improvement in power generation efficiency cannot be realized. In addition, the fluorescent particles or the phosphorescent fluorescent particles 1 contained therein
Light 165 having a wavelength that contributes to photoelectric conversion emitted from 62
Is radiated in a random direction, and about half of the light having a wavelength that contributes to photoelectric conversion is radiated in the direction opposite to the pin junction, 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 pin junction, which does not lead to improvement in power generation efficiency.

In such a situation, the fluorescent material 16 shown in FIG.
1 is used, p composed of the polycrystalline semiconductor shown in FIG.
Also in the case of thin film solar cells with n-junctions,
The same applies to the tandem structure thin-film solar cell in which the pn junction formed of the polycrystalline Si semiconductor shown in FIG. 14 and the pin junction formed of the amorphous Si semiconductor shown in FIG. 15 are laminated.

Therefore, an object of the present invention is to prevent the amount of light incident on the photoelectric conversion layer from being reduced even if there is surface-reflected light, and even if fluorescence is randomly emitted, this random emission is performed. Another object of the present invention is to provide a thin-film solar cell and a condensing reflective element that can effectively use the fluorescent light to increase power generation efficiency.

[0013]

In order to solve the above-mentioned problems, the thin-film solar cell of the present invention comprises a thin-film solar cell element having a photoelectric conversion layer, and a group of light transmission holes on a transparent substrate having fluorescent characteristics. The thin film solar cell element has a light-reflecting layer and a light-collecting element in which a condensing lens group for condensing incident light is sequentially provided on the light-transmitting hole group. The transparent substrate sides of the elements are opposed to each other, and a condensing reflection element is attached to the thin film solar cell element.

According to the above arrangement, the incident light is condensed in the light transmitting hole of the reflecting layer by the condenser lens group of the condenser reflecting element. Then, the light from the light transmitting hole is incident on a transparent substrate having a fluorescent property, is converted into light in a wavelength range that can be used for photoelectric conversion by the transparent substrate having the fluorescent property, and is randomly emitted and scattered. To be done. Radiation by the transparent substrate having this fluorescent property, light scattered and converted to light in the wavelength range that can be used for photoelectric conversion, the reflection layer of the condensing reflection element, and the photoelectric conversion layer of the thin film solar cell element Multiple reflections occur between. Therefore, the incident light is condensed by the condensing lens and passed through the light transmitting hole to effectively use the light passing through the light transmitting hole, and the transparent substrate having a fluorescent property is used for photoelectric conversion. The point where light in the wavelength range that cannot be converted is converted into light in the wavelength range that can be used for photoelectric conversion, the point where light is multiply reflected between the photoelectric conversion layer and the reflective layer and is irradiated to the photoelectric conversion layer, and the multiple reflection And, by the synergistic effect with the point that light in the wavelength range that cannot be used for photoelectric conversion due to the transparent substrate having fluorescent properties becomes light in the wavelength range that can be used for photoelectric conversion and is applied to the photoelectric conversion layer, the photoelectric conversion layer is irradiated. The amount of light in the wavelength range that contributes to the photoelectric conversion is significantly increased, resulting in extremely high power generation efficiency.

In one embodiment, the transparent substrate is fluorescent glass.

In the above-mentioned embodiment, since the fluorescent glass is used as the transparent substrate, the transparent substrate can easily have the fluorescent characteristic.

Further, in one embodiment, the transparent substrate 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 thin-film solar cell element includes a reflective layer located on the side opposite to the light incident surface with respect to the photoelectric conversion layer.

According to the above embodiment, since the photoelectric conversion layer is located between the reflection layer of the thin film solar cell element and the incident surface, the reflection layer of the solar cell element and the reflection of the condensing reflection element are reflected. Light is multiple-reflected between the reflective layer of the solar cell element and the reflective layer of the condensing reflective element with the photoelectric conversion layer and the transparent substrate having the fluorescent property interposed between the layers. 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.

Further, in one embodiment, the light transmitting hole of the condenser / reflector is a circular pinhole, and the condenser lens is a hemispherical condenser lens.

According to the above-mentioned embodiment, the incident light is efficiently condensed on the circular pinhole by the hemispherical condenser lens. Therefore, power generation efficiency can be increased.

Further, in one embodiment, the light transmission hole of the condenser reflection element is a linear slit, and the condenser lens is a cylindrical condenser lens.

According to the above-described embodiment, the incident light is efficiently condensed on the linear slit by the cylindrical condenser lens. Therefore, power generation efficiency can be increased.

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

In the above-mentioned embodiment, since the condenser lens is made of the ultraviolet curing 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.

Further, in one embodiment, the thin film solar cell element and the condensing reflection element are mechanically fixed via a spacer.

According to the above-described embodiment, since the light converging and reflecting element is mechanically fixed to the thin film solar cell element via the spacer, the light converging and reflecting element can be simply attached to the thin film solar cell element. Can be installed. Further, the thin-film solar cell element and the light-collecting and reflecting element can be easily separated and replaced with each other. Further, the thin film solar cell element can be protected by the light converging and reflecting element to improve the reliability of the thin film solar cell.

Further, in one embodiment, the thin film solar cell element and the light collecting and reflecting element are fixed by a transparent adhesive.

According to the above embodiment, since the light collecting and reflecting element is fixed to the thin film solar cell element with a transparent adhesive, the light collecting and reflecting element can be easily and firmly fixed to the thin film solar cell element. It is possible to obtain a highly reliable thin film solar cell having excellent environment resistance. Moreover, since a transparent adhesive is used, no light loss occurs.

In the converging / reflecting element of the present invention, a reflective layer having a group of light transmitting holes and a condenser lens group for condensing incident light on the group of light transmitting holes are formed on a transparent substrate having a fluorescent property. It is characterized by being provided.

When the condensing reflection element having the above-mentioned structure is attached to the conventional thin film solar cell, the thin film solar cell of the present invention can be constructed, and the power generation efficiency of the conventional thin film solar cell can be easily improved. it can.

[0033]

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 is a schematic cross-sectional view of the thin film solar cell of this embodiment, and FIG. 2 is a plan view of the thin film solar cell as seen from the light incident side.

The thin film solar cell element comprises a thin film solar cell element 100 and a condensing reflection element 200.

The thin-film solar cell element 100 has an electrode metal layer 2 having a light reflection effect as an example of a reflection layer and a-Si: H, a-SiGe: on a substrate 1 also serving as a support.
N or an n-type impurity-doped amorphous semiconductor layer 3 made of an amorphous semiconductor such as H or a-SiC: H;
The i layer 4 that is an amorphous intrinsic semiconductor layer, the p layer 5 that is a p-type impurity-doped amorphous semiconductor layer, the comb-shaped collector electrode 7 for taking out an electric current, and the transparent material such as SnO2, ITO, or ZnO. The conductive layer 8 is laminated in this order. The n layer 3 and i
The layer 4 and the p layer 5 form an example of the photoelectric conversion layer 6.

On the other hand, in the condensing reflection element 200, the reflective layer 11 having the circular pinhole group 12 as an example of the transmission hole group and the circular pinhole group 12 are provided on the transparent substrate 10 having the fluorescent property. A hemispherical condenser lens group 13 for condensing the incident light 14 is sequentially formed.

As the transparent substrate 10 having the above-mentioned fluorescent property, it is possible to use commercially available fluorescent glass, for example, fluorescent glass such as "Lumirus G9" manufactured by Sumita Optical Glass Co., Ltd. Further, as shown in FIG. 3, a transparent glass substrate 10 in which fluorescent particles or luminous fluorescent particles 16 are dispersed.
It is also possible to use.

The center of each of the hemispherical condenser lenses 13 is made to substantially overlap with the center of the circular pinhole 12 of the reflection layer 11, and the incident light 14 is caused by the hemispherical condenser lenses 13. Circular pinhole 12 of reflective layer 11
It is designed to collect light efficiently.

As shown in FIG. 2, the hemispherical condenser lens group 13 allows the transparent substrate 1 to capture as much of the incident light 14 on the condenser reflection element 200 as possible.
They are arranged on top of each other in a close-packed state. That is, a row composed of a plurality of hemispherical condensing lenses 13 arranged in the lateral direction is adjacent to each other in the upper and lower rows, and the arrangement pitch of the hemispherical condensing lenses 13 is shifted by a half pitch to form one hemispherical condensing lens. Six hemispherical condensing lenses 13 are arranged in contact with the circumference of 13.

When the thin-film solar cell having the above structure is irradiated with light such as sunlight, the incident light 14 is reflected by the hemispherical condensing lens group 13 of the condensing reflecting element 200 as shown in FIG. The light is focused on the circular pinhole group 12 formed above, passes through the transparent substrate 10 having a fluorescent property, and then enters the thin film solar cell element 100. Light incident on the thin-film solar cell element 100 passes through the transparent conductive layer 8 and the amorphous semiconductor layers 5, 4 and 3 and is reflected by the electrode metal layer 2 as a reflection layer, and again the amorphous semiconductor. Pass through layers 3, 4, and 5. Thereby, the light utilization efficiency in the photoelectric conversion layer 6 including the amorphous semiconductor layers 3, 4, and 5 is improved.
Further, the light reflected on the surfaces of the transparent dielectric layer 8, the collector electrode 7, and the amorphous semiconductor layer 5 is also reflected by the reflective layer 11 of the condensing reflective element 200, and the amorphous semiconductor is again provided. Pass through layers 5, 4, and 3. In this way, the light incident from the circular pinhole group 12 is multiply reflected between the reflective layer 11 and the thin-film solar cell element 9, whereby a higher light absorption efficiency is realized.

In the thin film solar cell of the present invention, the photoelectric conversion layer 6 is sandwiched between the reflective layer 11 of the condensing reflective element 200 and the reflective layer 2 of the thin film solar cell element 100 to reflect the condensing reflective element 200. Since multiple reflection is realized between the layer 11 and the reflective layer 2 of the thin-film solar cell element 100, incident light is sufficiently absorbed even when the amorphous semiconductor layers 3, 4, 5 are thinned. In addition, the traveling distance of electric charge is short, and the current that can be taken out to the outside can be increased.

Further, in the thin-film solar cell of the present embodiment, the transparent substrate 10 having the fluorescence characteristic of the condensing reflection element 200 allows the light in the wavelength region not used for photoelectric conversion in the photoelectric conversion layer 6 to be converted into photoelectric conversion. Since the light is converted into light in the used wavelength range, the power generation efficiency can be further increased.

The transparent substrate 10 having the above-mentioned fluorescent property will be described in more detail assuming that it is a transparent substrate 10 in which fluorescent particles or phosphorescent fluorescent particles 16 are dispersed as shown in FIG. Circular pinhole group 1 of the condensing reflection element 200
The light incident from 2 reflects the reflection layer 11 and the thin film solar cell element 1
00 and between the reflective layer 11 and the reflective layer 2 are not multiple-reflected and are not wastefully emitted to the outside, and the amount of light with which the photoelectric conversion layer 6 is irradiated is increased. Board 1
Since the fluorescent particles or the phosphorescent fluorescent particles 16 dispersed in 0 convert light in the wavelength range not used for photoelectric conversion into light in the wavelength range available for photoelectric conversion, the power generation efficiency of this thin film solar cell becomes extremely high. .

When the photoelectric conversion layer 6 is composed of a pin junction made of an amorphous Si semiconductor as described above,
The wavelength range of light used for photoelectric conversion (hereinafter referred to as photosensitive wavelength range) is 450 to 650 nm, and light outside this photosensitive wavelength range is consumed as heat without being used for photoelectric conversion.

Here, as shown in FIG. 3, the transparent substrate 10
When the fluorescent particles or the phosphorescent fluorescent particles 16 are dispersed in the above, light having a wavelength other than the above-mentioned photosensitive wavelength range is absorbed by the fluorescent particles or the phosphorescent fluorescent particles 16 and is exposed from the fluorescent particles or the phosphorescent fluorescent particles 16. By radiating light in the wavelength range, light having a wavelength other than the above-mentioned photosensitive wavelength range is converted into light in the photosensitive wavelength range, and power generation efficiency can be improved.

For example, the fluorescent particles 16 have a particle size of 5 to 2
By using 0 μm Y ₂ O ₂ S: Eu, Mg, Ti phosphorescent fluorescent particles, it is possible to absorb light with a wavelength of 200 to 450 nm and emit light with a wavelength of 625 nm. Further, by using oxyfluoride-based crystallized glass containing Er ³⁺ ions, it is possible to absorb light having a wavelength of around 800 nm and emit light having a wavelength of 550 to 660 nm.

As fluorescent materials other than these, a rare earth element europium (Eu) and dysprosium (D) are added to a compound consisting of strontium oxide and aluminum oxide.
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 the conventional thin film solar cell, as shown in FIG. 16, scattered light 164 scattered by fluorescent particles or phosphorescent fluorescent particles 162 and light emitted from the fluorescent particles or phosphorescent fluorescent particles 162. Part of 165 is
Although it did not enter the photoelectric conversion layers (pin junctions) 153, 154 and 155, it caused a decrease in power generation efficiency.
According to the present embodiment shown in FIGS. 1 and 3, the scattered light 17 scattered by the fluorescent particles or the phosphorescent fluorescent particles 16 and the light 18 emitted from the fluorescent particles or the phosphorescent fluorescent particles 16 are the reflective layer. The photoelectric conversion layer 6 is reflected by 11
Incident on. In this way, scattered light 17 and emitted light 1
8 is multiple reflection between the reflective layer 11 of the condensing reflective element 200 and the thin film solar cell element 100, and between the reflective layer 11 of the condensing reflective element 200 and the reflective layer 2 of the thin film solar cell element 100. By doing so, high power generation efficiency can be realized.

In FIG. 1 and FIG. 3, the case where an amorphous Si semiconductor layer as shown in FIG. 15 is used as a thin film solar cell element is explained, but polycrystalline Si as shown in FIG. 14 is used. Even in the case of a thin film solar cell element using a semiconductor layer, and a thin film solar cell element having a tandem structure using both a polycrystalline Si semiconductor layer and an amorphous Si semiconductor layer, similar multiple reflection is realized, The light absorption efficiency of the photoelectric conversion layer can be increased.

In the thin-film solar cell of this embodiment, as shown in FIG. 2, hemispherical lens groups 13 are arranged on the transparent substrate 10 via the reflection layer 11 so as to be in the closest packed state. Therefore, the area 15 where the incident light 14 is reflected by the reflective layer 11 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.

In the thin-film solar cell of the above-described embodiment, the hemispherical condenser lens groups 13 are arranged on the transparent substrate 10 so as to be in a close-packed state, and the region 15 where the incident light 14 is reflected by the reflective layer 11 is arranged. Is minimized and a large amount of light is condensed and passed through the circular pinhole group 12, and the light that is condensed by the hemispherical condenser lens 13 and has passed through the circular pinhole 12 is reflected by the reflection layer 11. In that the light is effectively used without being missed, and that the transparent substrate 10 having a fluorescent property converts light in a wavelength range that cannot be used for photoelectric conversion into light in a wavelength range that can be used for photoelectric conversion. Between the reflective layer 11 of the element 200 and the thin film solar cell element 100, and between the reflective layer 11 of the condensing reflective element 200 and the reflective element 2 of the thin film solar cell element 100, multiple reflection is performed to form the photoelectric conversion layer 6. For synergistic effect with irradiation point I, since the amount of light contributing wavelength region to the photoelectric conversion irradiated to the photoelectric conversion layer 6 is increased significantly, a very high power generation efficiency.

[0054]

Example 1 According to the process shown in FIGS. 4 to 10,
The reflective condensing element 100 of the thin-film solar cell of Example 1 was created.

First, as shown in FIG. 4, as a transparent substrate 10 having a fluorescent property, Y ₂ O ₂ S: Eu, having a diameter of 5 μm,
A reflective layer 11 made of Al _0.95 Ti _0.05 having a film thickness of 100 nm is formed on a transparent glass substrate 10 in which Mg and Ti phosphorescent fluorescent particles 16 (see FIG. 3) are dispersed in a volume ratio of about 20%. It was formed by sputtering. Although glass is used as the transparent substrate material in the first embodiment, cost reduction can be realized by using a transparent resin substrate such as a polycarbonate resin. Also, A
Although the lTi sputtered film is used as the reflection layer 11, any metal film having a high reflectance may be used.
A metal film of g, Au, Ti, or the like, and an alloy film composed of these metals can be used. In addition, the reflective film 11
The film thickness is preferably 40 nm or more at which light is almost completely reflected. However, if the reflective film 11 becomes too thick, it will cause an increase in film forming time and an increase in material cost.
It is preferably 150 nm or less.

Next, as shown in FIG. 5, the photoresist pattern 2 in which the photoresist in the region 19 corresponding to the circular pinhole group 12 is removed by the photoprocess.
0 was formed on the reflective layer 11. The diameter of the region 19 in the photoresist pattern 20 corresponding to the circular pinhole group 12 was 0.5 mm. Here, the photoresist pattern 20 is formed by the photo process, but the cost can be reduced by forming the resin pattern corresponding to the photoresist pattern 20 by using the screen printing technique.

Then, as shown in FIG. 6, the reflective layer 11 was wet-etched using dilute nitric acid using the photoresist pattern 20 as a mask to form a circular pinhole group 12.

Next, as shown in FIG. 7, the photoresist pattern 20 is removed by using an acetone solvent that does not erode the transparent glass substrate 10 and the AlTi reflective layer 11, and the reflective layer 11 having the circular pinhole group 12 is formed. A transparent glass substrate 10 having a fluorescent property is formed.

Next, as shown in FIG. 8, a transparent glass stamper 22 having a recess 21 corresponding to the hemispherical condenser lens group 13 is filled with an uncured ultraviolet curable resin 23, and each hemispherical collector is filled. After aligning so that the center position of the optical lens group 13 and the center position of the circular pinhole 12 coincide with each other, as shown in FIG.
2 and the transparent glass substrate 10 are brought into close contact with each other, the ultraviolet light 24 is irradiated through the transparent glass stamper 22 to cure the ultraviolet curable resin 23, and then the transparent glass stamper 22 is peeled off. By doing so, as shown in FIG. 10, the condensing reflecting element 200 including the hemispherical condensing lens group 13 and the reflecting layer 11 having the circular pinhole group 12 is completed.
The diameter of the hemispherical condenser lens 13 according to the first embodiment is 5 mm, and as shown in FIG.

On the other hand, the thin film solar cell element 1 shown in FIGS.
00 was produced by a method similar to the conventional method. That is,
Al having a film thickness of 100 nm, which has a light reflection effect to serve as a reflection layer, is formed on the stainless steel substrate 1 which also serves as a support.
After forming the _0.95 Ti _0.05 electrode metal layer 2 by sputtering, the n-type impurity-doped Si semiconductor layer n is formed.
A photoelectric conversion layer 6 in which a layer 3, an i layer 4 that is an intrinsic Si semiconductor, and a p layer 5 that is a p-type impurity Si-doped semiconductor layer are stacked in this order is chemically vapor-phased by a plasma CVD (chemical vapor deposition) apparatus. It was formed by the growth method. Each semiconductor layer was formed by vapor phase growth using a mixed gas of SiH ₄ gas / H ₂ gas / PH ₃ gas. The n-layer 3 of a-Si: H and the SiH ₄ gas / H ₂ gas each having a film thickness of 15 nm were used. 200-nm-thick a-Si: H i layer 4 vapor-grown using a mixed gas, SiH
_A -SiC: H having a film thickness of 15 nm grown by vapor phase growth using a mixed gas of ₄ gas / H ₂ gas / CH ₄ gas / B ₂ H ₆ gas
P layer 5.

Next, the substrate 1 on which the photoelectric conversion layer 6 is formed
Attached to the sputtering device and the shielding mask on the substrate 1
Al _0.95 Ti _0.05 nm thick with an AlTi alloy target attached to the surface of the semiconductor film of
Comb type collector electrode 7 with a width of 0.1 mm and a gap of 5 mm
Was formed.

Next, an In ₂ O ₃ target is used to perform reactive sputtering in an oxygen atmosphere to form an antireflection layer 8 having a film thickness of 65 nm on the photoelectric conversion layer 6 and the comb-shaped current collecting electrode 7. did.

Condensing reflection element 2 manufactured as described above.
00 and the thin film solar cell element 100 are mechanically fixed by a fixing metal fitting 26 through a urethane-based resin spacer 25 having elasticity, as shown in FIG. 11, to complete the thin film solar cell of Example 1. .

Further, the thin film solar cell element 100 to which the reflective condensing element 200 was not attached was used as the thin film solar cell of Comparative Example 1.

For the thin-film solar cell of Example 1 and the thin-film solar cell of Comparative Example 1, the AM1.5 simulator was used.
When the IV characteristic was measured by irradiating with light of 00 mW / cm ² , the thin-film solar cell of Example 1 had an open circuit voltage of about 30% larger than that of the thin-film solar cell of Comparative Example 1 and a short-circuit current. It was confirmed that it was about 35% larger. Therefore, it was found that the thin film solar cell of Example 1 had a photoelectric conversion efficiency of about 76% higher than that of the thin film solar cell of Comparative Example 1 (conventional thin film solar cell).

Although the thin film solar cell in which only one set of the photoelectric conversion layer 6 composed of the pin junction is formed is described in the first embodiment, the light utilization efficiency is improved by the multiple reflection in the present invention. I, which is an intrinsic semiconductor
Even when the layer 4 is thin, it is possible to absorb light sufficiently in the pin junction. Therefore, it is possible to further improve the open circuit voltage by stacking a plurality of sets of photoelectric conversion layers 6 each having a pin junction in which the i layer 4 which is an intrinsic semiconductor is further thinned.

[0067]

Second Embodiment As shown in FIG. 12, the thin film solar cell of the second embodiment has a condensing reflective element 200 manufactured in the first embodiment.
The thin-film solar cell element 100 and the thin-film solar cell element 100 are attached to each other with an acrylic transparent adhesive 27. With such a configuration, the light converging / reflecting element 200 and the thin film solar cell element 100 can be fixed easily and firmly, and a highly reliable thin film solar cell having excellent environmental resistance can be obtained. Further, since the transparent adhesive is used, problems such as loss of light do not occur even if the transparent adhesive sticks out.

The thin film solar cells of Examples 1 and 2 were subjected to an environmental test for 2 months at an ambient temperature of 80 ° C. and a relative humidity of 80%. As a result, in the thin film solar cells of Example 1, urethane was obtained. High-humidity air entered between the light-collecting reflective element 200 and the thin-film solar cell element from the resin-based spacer 25, and the thin-film solar cell element started to corrode, resulting in a 20% decrease in power generation efficiency. On the other hand, it was confirmed that the thin-film solar cell of Example 2 bonded with the acrylic transparent adhesive 22 has excellent environmental resistance without causing a change in appearance or a decrease in power generation efficiency.

[0069]

[Third Embodiment] FIG. 13 is a perspective sectional view of a thin film solar cell according to a third embodiment. The thin-film solar cell of Example 3 includes a thin-film solar cell element 100 and a condensing reflection element 300. The thin-film solar cell element 100 has exactly the same structure as the thin-film solar cell element 100 of the first embodiment, and only the condensing and reflecting element 300 is different from the condensing and reflecting element 200 of the first embodiment.

In the first embodiment, the converging / reflecting element 2 is used.
00 denotes a transparent substrate 10 having a fluorescent characteristic, a reflective layer 11 having a circular pinhole group 12 formed on the transparent substrate 10, and incident light 1 to the circular pinhole group 12.
The thin film solar cell of the third embodiment has a transparent substrate 10 having a fluorescent property and the transparent substrate 10 which is transparent. A reflective layer 29 formed on the substrate 10 and having a linear slit group 28 as a light transmission hole, and a cylindrical condenser lens group 30 arranged to condense the incident light 14 on the linear slit group 28. It consists of and.

Also in this case, as in the first embodiment, the light incident from the linear slit group 28 is multiply reflected between the reflective layer 29 of the condensing reflective element 300 and the thin film solar cell element 100. The light utilization efficiency in the photoelectric conversion layer 6 is increased, and the power generation efficiency can be increased.

The condensing reflection element 300 is shown in FIGS.
It is manufactured in the same manner as the process of Example 1 shown in FIG. Then, the light converging / reflecting element 300 and the thin-film solar cell element 100 were attached to each other with an acrylic transparent adhesive (not shown) to manufacture a thin-film solar cell of Example 3.
In the third embodiment, since the condensing reflection element 300 and the thin-film solar cell element 100 are adhered to each other with an acrylic transparent adhesive, they can be easily and firmly fixed to each other and have excellent environmental resistance and reliability. A high thin film solar cell can be obtained. Further, since the transparent adhesive is used, problems such as loss of light do not occur even if the transparent adhesive sticks out.

The thin film solar cell of Example 3 and the thin film solar cell of Comparative Example 1 were irradiated with light of 100 mW / cm ² with an AM1.5 simulator, and the IV characteristics were measured. The thin film solar cell of No. 3 is the above Comparative Example 1
It was confirmed that the open-circuit voltage was about 28% higher and the short-circuit current was about 33% higher than that of the thin-film solar cell. Therefore, it was found that the thin film solar cell of Example 3 had a photoelectric conversion efficiency of about 70% higher than that of the thin film solar cell of Comparative Example 1.

The converging / reflecting element 20 of Examples 1, 2, and 3 above.
0, 300 can be easily used in combination with a conventional thin film solar cell, and can improve the power generation efficiency of the conventional thin film solar cell.

[0075]

As is apparent from the above, according to the thin-film solar cell of the present invention, incident light is condensed by the condenser lens of the condenser reflection element and transmitted through the light transmission hole of the reflection layer. Light in the wavelength range that can be effectively used without allowing the light that has passed through the holes to escape in the reflective layer, and light in the wavelength range that cannot be used for photoelectric conversion due to the transparent substrate having the fluorescent characteristics of the condensing reflection element Can be converted into, and the light can be multiple-reflected between the photoelectric conversion layer and the reflective layer to increase the amount of light applied to the photoelectric conversion layer, and a transparent substrate having fluorescent characteristics and multiple reflection can be used for photoelectric conversion. Since it is possible to irradiate the photoelectric conversion layer with light in a wavelength range that cannot be used for photoelectric conversion and to irradiate the photoelectric conversion layer, it is possible to remarkably increase the amount of light in the wavelength range that contributes to photoelectric conversion that is irradiated on the photoelectric conversion layer. , Extremely high power generation efficiency It is possible.

In one embodiment, since the fluorescent glass is used as the transparent substrate, the transparent substrate can easily have the fluorescent characteristic.

Further, 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.

Further, in one embodiment, the thin-film solar cell element is provided with a reflective layer located on the side opposite to the light incident surface with respect to the photoelectric conversion layer, and the thin film solar cell element includes a reflective layer of the solar cell element and a condensing reflective element. Since a photoelectric conversion layer and a transparent substrate having a fluorescent property are sandwiched between the reflective layer and the reflective layer of the solar cell element and the reflective layer of the condensing reflective element, light is multiply reflected. It is possible to remarkably increase the light amount of the light in the wavelength range that contributes to the photoelectric conversion and irradiate the conversion layer, so that the power generation efficiency can be made extremely high.

Further, in one embodiment, since the light transmission hole of the condenser reflection element is a circular pinhole and the condenser lens is a hemispherical condenser lens, incident light can be efficiently transmitted.
It is possible to increase the power generation efficiency by focusing on the circular pinhole.

Further, in one embodiment, since the light transmission hole of the condenser reflection element is a linear slit and the condenser lens is a cylindrical condenser lens, the incident light can be efficiently reflected by the straight line. It is possible to increase the power generation efficiency by condensing the light into the slits.

In one embodiment, since the condenser lens is made of ultraviolet curable resin, the 2P method (photopolymerization method: Photo
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.

Further, in one embodiment, since the light collecting and reflecting element is mechanically fixed to the thin film solar cell element via the spacer, the light collecting and reflecting element can be easily attached to the thin film solar cell element. You can Further, the thin-film solar cell element and the light-collecting and reflecting element can be easily separated and replaced with each other. Further, the thin film solar cell element can be protected by the light converging and reflecting element to improve the reliability of the thin film solar cell.

Further, in one embodiment, since the light collecting and reflecting element is fixed to the thin film solar cell element by the transparent adhesive, the light collecting and reflecting element can be easily and firmly fixed to the thin film solar cell element, and It is possible to obtain a highly reliable thin film solar cell having excellent environmental properties.

The condensing / reflecting element of the present invention comprises, on a transparent substrate having a fluorescent property, a reflecting layer having a group of light transmitting holes, and a group of condensing lenses for condensing incident light to the group of light transmitting holes in order. Since it is provided, when the present condensing reflective element is attached to the conventional thin film solar cell, the power generation efficiency of the conventional thin film solar cell can be easily improved.

[Brief description of drawings]

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

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

FIG. 3 is a cross-sectional view illustrating a function of fluorescent particles of the thin film solar cell.

FIG. 4 is a diagram showing a method for manufacturing the condensing reflective element of the thin-film solar cell of Example 1 of the present invention.

FIG. 5 is a diagram showing a method for manufacturing the condensing reflective element of the thin-film solar cell of Example 1 of the present invention.

FIG. 6 is a diagram showing a method for manufacturing the condensing reflective element of the thin-film solar cell of Example 1 of the present invention.

FIG. 7 is a diagram showing a method for manufacturing the condensing reflective element of the thin-film solar cell of Example 1 of the present invention.

FIG. 8 is a diagram showing a method for manufacturing the condensing reflective element of the thin-film solar cell of Example 1 of the present invention.

FIG. 9 is a diagram showing a method for manufacturing the condensing reflective element of the thin-film solar cell of Example 1 of the present invention.

FIG. 10 is a diagram showing a method for manufacturing the condensing reflective element of the thin-film solar cell of Example 1 of the present invention.

FIG. 11 is a cross-sectional view of the thin-film solar cell of Example 1 of the present invention.

FIG. 12 is a cross-sectional view of a thin film solar cell according to a second embodiment of the present invention.

FIG. 13 is a cross-sectional perspective view of a thin film solar cell of Example 3 of the present invention.

FIG. 14 is a cross-sectional view of a conventional thin film solar cell.

FIG. 15 is a cross-sectional view of a conventional thin film solar cell.

FIG. 16 is a cross-sectional view of a conventional thin film solar cell.

[Explanation of symbols]

1 substrate 2 electrode metal layer 3,4,5 Amorphous Si semiconductor layer 6 Photoelectric conversion layer 10 Transparent substrate having fluorescent characteristics 11,29 Reflective layer 12 circular pinholes 13 hemispherical condenser lens 16 Fluorescent particles or phosphorescent fluorescent particles 23 UV curable resin 25 spacer 26 Fixing bracket 27 Transparent adhesive 28 Linear slit 30 Cylindrical condensing lens 100 thin film solar cell element 200,300 Condensing reflection element

Claims (10)

[Claims] 1. A thin-film solar cell element having a photoelectric conversion layer, a reflective layer having a group of light transmitting holes on a transparent substrate having a fluorescent property, and a condenser lens for collecting incident light on the group of light transmitting holes. And a transparent condensing element of the thin-film solar cell element facing the light incident surface of the thin-film solar cell element. Is attached to the thin film solar cell. 2. The thin film solar cell according to claim 1, wherein the transparent substrate is fluorescent glass. 3. The thin film solar cell according to claim 1, wherein the transparent substrate is a transparent substrate in which fluorescent particles or phosphorescent fluorescent particles are dispersed. 4. The thin-film solar cell according to claim 1, wherein the thin-film solar cell element includes a reflective layer located on the side opposite to the light incident surface with respect to the photoelectric conversion layer. A thin film solar cell characterized by the above. 5. The thin-film solar cell according to claim 1, wherein the light transmitting hole of the condensing reflecting element is a circular pinhole, and the condensing lens is a hemispherical collector. A thin-film solar cell, which is a light lens. 6. The thin-film solar cell according to claim 1, wherein the light transmission hole of the condensing reflection element is a linear slit.
A thin-film solar cell, wherein the condenser lens is a cylindrical condenser lens. 7. The thin film solar cell according to claim 1, wherein the condenser lens is made of an ultraviolet curable resin. 8. The thin-film solar cell according to claim 1, wherein the thin-film solar cell element and the condensing reflection element are mechanically fixed via a spacer. Characteristic thin film solar cell. 9. The thin-film solar cell according to claim 1, wherein the thin-film solar cell element and the condensing reflective element are fixed by a transparent adhesive. Thin film solar cell. 10. A transparent substrate having a fluorescent property, on which a reflective layer having a group of light transmitting holes and a group of condenser lenses for condensing incident light to the group of light transmitting holes are sequentially provided. A condensing reflection element.