KR20130049997A - Thin film solar cell - Google Patents

Thin film solar cell Download PDF

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KR20130049997A
KR20130049997A KR1020110115100A KR20110115100A KR20130049997A KR 20130049997 A KR20130049997 A KR 20130049997A KR 1020110115100 A KR1020110115100 A KR 1020110115100A KR 20110115100 A KR20110115100 A KR 20110115100A KR 20130049997 A KR20130049997 A KR 20130049997A
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solar cell
thin film
film solar
micro lenses
electrode layer
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KR1020110115100A
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Korean (ko)
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KR101784440B1 (en
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김수현
이홍철
정진원
안세원
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엘지전자 주식회사
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/02—Details
    • H01L31/0224—Electrodes
    • H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
    • H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/042—PV modules or arrays of single PV cells
    • H01L31/0445—PV modules or arrays of single PV cells including thin film solar cells, e.g. single thin film a-Si, CIS or CdTe solar cells
    • H01L31/046—PV modules composed of a plurality of thin film solar cells deposited on the same substrate
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
    • H01L31/054—Optical elements directly associated or integrated with the PV cell, e.g. light-reflecting means or light-concentrating means
    • H01L31/0543—Optical elements directly associated or integrated with the PV cell, e.g. light-reflecting means or light-concentrating means comprising light concentrating means of the refractive type, e.g. lenses
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/52—PV systems with concentrators

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  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Electromagnetism (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Photovoltaic Devices (AREA)
  • Sustainable Energy (AREA)

Abstract

PURPOSE: A thin film solar cell is provided to improve photoelectric conversion efficiency by including a plurality of microlenses in a second electrode. CONSTITUTION: A first electrode(110) is arranged on a substrate. A second electrode(130) is arranged on the upper side of the first electrode. A photoelectric conversion unit is arranged between the first electrode and the second electrode and converts light into electricity by receiving the light. The second electrode includes a plurality of microlenses(135). [Reference numerals] (AA,BB) Light

Description

Thin Film Solar Cells {THIN FILM SOLAR CELL}

The present invention relates to a thin film solar cell.

Recently, as energy resources such as oil and coal are expected to be depleted, interest in alternative energy to replace them is increasing, and solar cells that produce electric energy from solar energy are attracting attention.

Typical solar cells have a semiconductor portion that forms a p-n junction by different conductive types, such as p-type and n-type, and electrodes connected to semiconductor portions of different conductivity types, respectively.

When light is incident on the solar cell, a plurality of electron-hole pairs are generated in the semiconductor, and the generated electron-hole pairs are separated into electrons and holes, which are electric charges, and the electrons move toward the n-type semiconductor portion, and the holes are p-type. Move toward the semiconductor portion. The transferred electrons and holes are collected by the different electrodes connected to the p-type semiconductor portion and the n-type semiconductor portion, respectively, and the electrodes are connected by a wire to obtain electric power.

An object of the present invention is to provide a thin film solar cell with improved efficiency.

One example of a thin film solar cell according to the present invention includes a substrate; A first electrode disposed on the substrate; A second electrode disposed on the first electrode; And a photoelectric conversion unit disposed between the first electrode and the second electrode and configured to receive light and convert light into electricity. The second electrode includes a plurality of micro lenses.

Here, the second electrode includes a transparent electrode layer containing a light transmissive conductive material and a metal electrode layer containing a light transmissive conductive material, and the plurality of micro lenses are positioned between the transparent electrode layer and the metal electrode layer, and the light transmissive vision May comprise a conductive material. The transparent electrode layer may contact the photoelectric converter, and the metal electrode layer may contact the transparent electrode layer and the plurality of micro lenses.

Here, the plurality of micro lenses may include a resin-based material. For example, the resin-based material may include at least one of a polymer or a monomer-based carbon polymer, a monomer, or glycerin.

In addition, the plurality of micro lenses may include a first surface in contact with the transparent electrode layer and a second surface in contact with the metal electrode layer, the second surface may include a curved surface, and the first surface may include a plurality of irregularities.

Also, in the plurality of micro lenses, the thickness of the edge portion may be smaller than the thickness of the central portion.

In addition, the first electrode may include a plurality of irregularities, the diameter of at least one of the plurality of micro lenses may be greater than a distance between protrusions of the irregularities included in the first electrode, and the maximum thickness of at least one of the plurality of micro lenses. May be greater than the protruding height of the unevenness included in the first electrode.

For example, the diameter of each of the plurality of micro lenses may be between 1 μm and 15 μm, and the ratio of the maximum thickness of each of the plurality of lenses to the diameter of each of the plurality of micro lenses may be between 1: 0.2 and 0.5.

In addition, the ratio of the total area occupied by the first surfaces of the plurality of microlenses to the total area of the transparent electrode layer may be 1: 0.25 to 0.75.

In addition, two micro lenses positioned in different adjacent rows among the plurality of micro lenses may be positioned in the same column or in different columns.

In addition, the plurality of micro lenses may include a first lens formed with a first diameter and a second lens formed with a second diameter smaller than the first diameter, and the second lens may be positioned between the first lenses.

Here, the first diameter may be between 1.5 times and 2.5 times the second diameter.

In addition, the photoelectric conversion unit may have at least one p-i-n structure including a P-type semiconductor layer, an intrinsic (i) semiconductor layer, and an n-type semiconductor layer.

In addition, the transparent electrode layer includes zinc oxide (ZnOx), tin oxide (SnOx), indium oxide (InOx), silicon oxide (SiOx), boron zinc oxide (ZnO: B, BZO) and aluminum zinc oxide (ZnO: Al, AZO). It may include at least one of the materials.

In addition, the thickness of the transparent electrode layer may be between 50nm ~ 1.5㎛.

In the solar cell according to the present invention, since the second electrode includes a plurality of micro lenses, internal reflection is effectively caused by the micro lenses. Therefore, there is an effect of further improving the photoelectric conversion efficiency of the photoelectric conversion section.

1 is a view for explaining an example of a thin film solar cell according to the present invention.
2A to 2C are views for explaining an example in which the lenses of the thin film solar cell according to the present invention are arranged on the transparent electrode layer.
FIG. 3 is a view for explaining an example in which the photoelectric conversion unit PV of the solar cell module according to the present invention includes a double junction solar cell or a pinpin structure.
4 is a view for explaining an example when the solar cell module according to the present invention includes a triple junction solar cell or a pinpinpin structure.
5A to 5E are diagrams for explaining an example of the method for manufacturing a thin film solar cell according to the present invention.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

In the drawings, the thickness is enlarged to clearly represent the layers and regions. When a layer, film, region, plate, or the like is referred to as being "on" another portion, it includes not only the case directly above another portion but also the case where there is another portion in between. Conversely, when a part is "directly over" another part, it means that there is no other part in the middle. In addition, when a part is formed “overall” on another part, it means that it is not only formed on the entire surface (or front) of the other part but also on the edge part.

1 is a view for explaining an example of a thin film solar cell according to the present invention.

As shown in FIG. 1, an example of a thin film solar cell according to the present invention includes a substrate 100, a first electrode 110, a photoelectric conversion unit PV, a second electrode 130, and a second electrode. 130 includes a plurality of micro lenses 135 spaced apart from each other.

As illustrated in FIG. 1, the structure of the photoelectric conversion unit PV becomes a p-i-n structure from the incident surface, but the structure of the photoelectric conversion unit PV may be an n-i-p structure from the incident surface. However, hereinafter, the structure of the photoelectric conversion unit PV becomes a p-i-n structure from the incident surface for convenience of explanation.

Here, the substrate 100 may be made of a substantially transparent non-conductive material, for example, glass or plastic material, in order to allow the incident light to reach the photoelectric conversion part PV more effectively.

The first electrode 110 is disposed on the substrate 100 and contains a substantially transparent conductive material to increase the transmittance of incident light.

For example, the conductive material forming the first electrode 110 may be formed of indium tin oxide (ITO), tin oxide (SnO 2, etc.), AgO, ZnO- () having high light transmittance and high electrical conductivity. Ga 2 O 3 or Al 2 O 3 ), fluorine tin oxide (FTO), boron zinc oxide (ZnO: B, BZO) and aluminum zinc oxide (ZnO: Al, AZO) .

The first electrode 110 may be electrically connected to the photoelectric conversion unit PV. Accordingly, the first electrode 110 may collect and output one of the carriers generated by the incident light, for example, holes.

In addition, a plurality of irregularities having a random pyramid structure may be formed on the upper surface of the first electrode 110. That is, the first electrode 110 has a texturing surface.

As such, when the surface of the first electrode 110 is textured, the reflection of incident light can be reduced and the absorption of light can be increased, thereby improving the efficiency of the solar cell.

Next, the second electrode 130 is spaced above the first electrode 110 and disposed above the photovoltaic unit PV, and has an electrical conductivity to increase recovery efficiency of power generated by the photovoltaic unit PV. It may comprise an excellent metal material.

In addition, the second electrode 130 may collect and output one of the carriers generated by the incident light, for example, electrons, which are electrically connected to the photoelectric conversion unit PV.

The second electrode 130 includes a transparent electrode layer 131 and a metal electrode layer 135. The transparent electrode layer 131 is positioned between the photoelectric conversion part PV and the metal electrode layer 135 to minimize contact resistance between the photoelectric conversion part PV and the metal electrode layer 135, and the metal electrode layer 135. ) Collects carriers generated in the photoelectric conversion unit PV through the transparent electrode layer 131. In some cases, the transparent electrode layer 131 may be omitted.

As described above, the second electrode 130 includes a plurality of micro lenses 135. The plurality of micro lenses 135 include a light transmissive non-conductive material, and function to reflect and scatter incident light. A detailed description thereof will be described later.

Next, the photoelectric conversion unit PV is disposed between the first electrode 110 and the second electrode 130 to convert light incident from the outside through the incident surface of the substrate 100 into electricity.

The photoelectric conversion part PV may include a pin structure, that is, a p-type semiconductor layer 120p, an intrinsic (i-type) semiconductor layer 120i, and an n-type semiconductor layer 120n from an incident surface of the substrate 100. Can be.

Here, the p-type semiconductor layer 120p may be formed by using a gas containing impurities of trivalent elements such as boron, gallium, indium, etc. in the source gas containing silicon (Si).

The intrinsic (i) semiconductor layer can reduce the recombination rate of the carrier and absorb light. The intrinsic semiconductor layer 120i may absorb incident light and generate carriers such as electrons and holes.

The intrinsic semiconductor layer 120i may include amorphous silicon (a-si) or microcrystalline silicon (mc-Si) material.

The n-type semiconductor layer 120n may be formed by using a gas containing impurity of pentavalent element, such as phosphorus (P), arsenic (As), and antimony (Sb), in the source gas containing silicon.

The photoelectric conversion unit PV may be formed by chemical vapor deposition (CVD), such as plasma enhanced chemical vapor deposition (PECVD).

In addition, as illustrated in FIG. 1, a doping layer such as the p-type semiconductor layer 120p and the n-type semiconductor layer 120n of the photoelectric conversion unit PV has a pn junction between the intrinsic semiconductor layer 120i. Can be formed.

In this structure, when light is incident toward the p-type semiconductor layer 120p, the depletion is caused by the p-type semiconductor layer 120p and the n-type semiconductor layer 120n having a relatively high doping concentration inside the intrinsic semiconductor layer 120i. (depletion) is formed, and thus an electric field can be formed. Due to the photovoltaic effect, electrons and holes generated in the intrinsic semiconductor layer 120i as the light absorbing layer are separated by the contact potential difference and moved in different directions. For example, holes may move toward the first electrode 110 through the p-type semiconductor layer 120p, and electrons may move toward the second electrode 130 through the n-type semiconductor layer 120n. Power can be produced in this way.

Meanwhile, the plurality of micro lenses 135 included in the second electrode 130 will be described in more detail as follows.

As shown in FIG. 1, the second electrode 130 further includes a plurality of micro lenses 135 arranged to be spaced apart from each other and including a light-transmissive non-conductive material, and the plurality of micro lenses 135 are transparent. It may be located between the electrode layer 131 and the metal electrode layer 135. It is also possible to form a plurality of micro lenses between the substrate 100 and the first electrode 110, in this case, Since the first electrode and the photoelectric conversion part must be deposited afterwards, thermal deformation of the microlens occurs due to heat generated during the deposition process of the first electrode and the photoelectric conversion part, and impurities inside the device are caused by out-gasing. Penetration causes the device to deteriorate.

In addition, in order to prevent a crack from occurring inside the device due to the microlens and a leakage current, a limitation in designing the shape (size and thickness, etc.) of the microlens is large.

In addition, when the microlens is formed of a polymer-based material, the crystallinity of the first electrode is decreased when the first electrode is formed, so that the conductivity of the first electrode is lowered, and the characteristics of the first electrode are due to impurity penetration from the microlens. There is a problem such as fluctuation.

In order to solve the above problems, in the present invention, the plurality of micro lenses 135 is positioned between the transparent electrode layer 131 and the metal electrode layer 135.

That is, when the plurality of micro lenses 135 are positioned between the transparent electrode layer 131 and the metal electrode layer 135, the micro lenses 135 are deposited after depositing the first electrode 110 and the photoelectric conversion unit PV. As a result, deterioration of the device due to a high temperature process can be prevented, and since the crack is not generated inside the device, the shape of the microlens can be formed by various methods, and the conductivity of the first electrode can be prevented from being lowered.

In addition, the effect of more efficiently reflecting and scattering light in the medium and long wavelength bands of 700 nm or more transmitted through the photoelectric conversion unit PV can be obtained.

Here, the transparent electrode layer 131 may be in contact with the photoelectric conversion unit PV and include an uneven surface as shown in FIG. 1, and may include a light-transmitting conductive material through which light is transmitted. In addition, the metal electrode layer 135 may be in contact with the transparent electrode layer 131 and the plurality of micro lenses 135, and may include an optically transmissive conductive material that does not transmit light.

As illustrated in FIG. 1, the plurality of micro lenses 135 reflect light incident through the photoelectric conversion part PV back into the photoelectric conversion part PV, so that the incident light is scattered. There is an effect of expanding the optical path in the conversion unit PV.

Accordingly, the light absorption rate of the photoelectric conversion part PV may be further improved to improve the photoelectric conversion efficiency of the photoelectric conversion part PV.

The transparent electrode layer 131 may be formed of indium tin oxide (ITO), tin oxide (SnO 2, etc.), AgO, ZnO (Ga 2 O 3 or Al 2 O 3 ) , fluorine tin oxide (fluorine tin) oxide: FTO), silicon oxide (SiOx), boron zinc oxide (ZnO: B, BZO) and aluminum zinc oxide (ZnO: Al, AZO) may include at least one, and may be formed in a single layer or multiple layers. .

The thickness of the transparent electrode layer 131 is preferably formed between 50 nm and 1.5 μm in consideration of the contact area with the metal electrode layer 135 and the series resistance of the device.

In addition, the metal electrode layer 135 may be formed of at least one of silver (Ag) or aluminum (Al) having good electrical conductivity, and may be formed of a single layer or a multilayer. In addition, the plurality of micro lenses 135 may be formed at a low temperature. It may include at least one of a polymer or monomer-based carbon polymer or monomer or glycerin capable of a printing process.

As illustrated in FIG. 1, the plurality of micro lenses 135 may include a first surface 135F1 in contact with the transparent electrode layer 131 and a second surface 135F2 in contact with the metal electrode layer 135. .

Here, the first surface 135F1 of the lens 135 includes an unevenness corresponding to the uneven surface of the transparent electrode layer 131, and the second surface 135F2 includes a curved surface and has an edge portion of the lens 135. Since the thickness is smaller than the thickness of the central portion of the lens 135, the second surface 135F2 may be convex from the first surface 135F1, and may have the shape of the concave lens 135 with respect to the direction in which light is incident. . Accordingly, as shown in FIG. 1, light passing through the photoelectric conversion part PV is incident into the photoelectric conversion part PV while reflecting and scattering by the inclined plane of the second surface of the microlens 135. do.

The diameter or width W135 of at least one of the plurality of microlenses 135 may be greater than the interval W110 between protrusions of the unevenness included in the first electrode 110, and the plurality of microlenses 135 The at least one maximum thickness H135 may be greater than the protrusion height H110 of the unevenness included in the first electrode 110.

Accordingly, the plurality of micro lenses 135 reflects light having a medium wavelength or long wavelength band of 700 nm or more from the light passing through the photoelectric conversion part PV back into the photoelectric conversion part PV, so that incident light is scattered. Therefore, there is an effect of expanding the optical path in the photoelectric conversion unit PV.

Thereby, the photoelectric conversion efficiency of a thin film solar cell can be improved further.

More specifically, the size of the unevenness of the first electrode 110 formed on the interface with the photoelectric conversion part PV is mostly less than 1 μm, that is, the interval W110 between the protrusions of the unevenness is 1 μm or less, Unevenness | corrugation whose protrusion height H110 is 1 micrometer or less is formed.

The unevenness of the first electrode 110 having such a size causes scattering with respect to light of 400 nm to 700 nm among the light of 400 nm to 1100 nm incident on the thin film solar cell, and thus, within the photoelectric conversion part PV. Although the optical path can be increased to absorb the light well, the roughness of the unevenness is too small for the remaining 700 nm to 1100 nm, so that the light is not scattered and the photoelectric conversion unit (PV) is used as it is. ) Is transmitted.

In this case, the light of 700 nm to 1100 nm has a relatively short optical path, and thus the amount of light absorbed in the photoelectric conversion unit PV is significantly reduced, thereby reducing the photoelectric conversion efficiency of the thin film solar cell.

However, like the thin film solar cell according to the present invention, the second electrode 130 includes a plurality of micro lenses 135 including a light transmissive material, and the diameter or width of at least one of the plurality of micro lenses 135. Medium and long wavelength light of 700 nm to 1100 nm when W135 and the maximum thickness H135 are larger than the unevenness included in the first electrode 110 to increase the roughness of the second electrode 130. Also, reflection and scattering can be caused to occur well, and the light absorption rate in the photoelectric conversion unit PV can be further increased.

The diameter or width W135 of each of the plurality of micro lenses 135 may be, for example, between 1 μm and 15 μm.

In addition, the ratio of the maximum thickness H135 of each of the microlenses 135 to the width W135 of the microlens 135 may be 1: 0.2 to 0.5. The scattering of light in the microlens 135, and the portion of the photoelectric converter PV that increases the light path of the light is a curved inclined surface included in the second surface 135F2 of the microlens 135. This is because the maximum thickness H135 of each of the microlenses 135 for properly forming the curved inclined surface is between 0.2 and 0.5 times the width W135 of the microlens 135.

More specifically, the reason why the maximum thickness H135 of the microlens 135 is greater than 1: 0.2 compared to the width or diameter W135 of the microlens 135 is to obtain a minimum light scattering effect. The reason why it is 0.5 or less is to prevent the amount of light absorbed from the microlens 135 itself may be relatively large when the maximum thickness of the microlens is excessively thick.

Here, the maximum thickness H135 of the microlens 135 refers to the thickness of the thickest portion of one microlens 135.

Until now, as illustrated in FIG. 1, an example of a thin film solar cell including a plurality of micro lenses 135 inside the second electrode 130 has been described. Hereinafter, the metal electrode layer 135 is removed. When looking at the rear surface of the thin film solar cell, how the plurality of lenses 135 are arranged on the transparent electrode layer 131 will be described.

2A to 2C are views for explaining an example in which the lenses of the thin film solar cell according to the present invention are arranged on the transparent electrode layer.

2A to 2C illustrate an example in which a plurality of micro lenses 135 are arranged on the transparent electrode layer 131, but are not necessarily limited thereto.

Two micro lenses 135 positioned in different adjacent rows among the micro lenses 135 may be located in the same column or in different columns.

For example, as shown in FIG. 2A, two micro lenses 135a and 135b positioned in different adjacent rows 135D1 and 135D2 may be arranged in a grid form by being located in the same column 135H1. As shown in FIG. 2B, two lenses 135a and 135b located in adjacent different rows 135D1 and 135D2 may be located in different columns 135H1 and 135H2.

In addition, the plurality of microlenses 135 according to the present invention may have a first microlens 135R1 having a first width in diameter and a second microlens 135R2 having a second width smaller in diameter than the first microlens 135R1. It may include. Here, the first width may be formed between 1.5 and 2.5 times the second width.

In this case, as shown in FIG. 2C, the second micro lens 135R2 may be located between the first micro lenses 135R1. Alternatively, the first microlens 135R1 and the second microlens 135R2 may be alternately arranged with the first microlens 135R1 and the second microlens 135R2 in a lattice form as described with reference to FIG. 2A. It may be.

In this case, the first microlens 135R1 having a relatively large first width reflects and scatters light of a long wavelength band, and the second microlens 135R2 having a second width having a relatively small diameter It reflects and scatters light in short wavelength band. By varying the width of the lens 135 as described above, light in the medium wavelength band and the long wavelength band of 700 nm or more can be reflected and scattered more precisely, thereby further improving the photoelectric conversion efficiency of the thin film solar cell. Can be.

1 and 2A to 2C, the ratio of the area occupied by the first surface 135F1 of the microlens 135 in contact with the transparent electrode layer 131 to the total area of the transparent electrode layer 131 is 1. : May be between 0.25 and 0.75.

Here, the ratio of the area occupied by the first surface 135F1 of the microlens 135 to the total area of the transparent electrode layer 131 to be greater than or equal to 1: 0.25 is the medium wavelength and the long wavelength of 700 nm or more due to the microlens 135. This is to secure the reflection and scattering effect of the least.

In addition, the ratio of the area occupied by the first surface 135F1 of the microlens 135 to the total area of the transparent electrode layer 131 to be less than or equal to 1: 0.75 indicates that the microlens 135 includes a nonconductive material. In consideration of this, the contact resistance between the transparent electrode layer 131 and the metal electrode layer 135 is at least secured.

In more detail, the transparent electrode layer 131 and the metal electrode layer 135 contain a conductive material, and the microlens 135 includes a nonconductive material. In this case, when the area occupied by the plurality of micro lenses 135 positioned between the transparent electrode layer 131 and the metal electrode layer 135 increases, the contact resistance between the transparent electrode layer 131 and the metal electrode layer 135 is relatively increased. Can be high.

Therefore, even if the area occupied by the plurality of microlenses 135 increases, the ratio of the area occupied by the first surface 135F1 of the microlens 135 to the total area of the transparent electrode layer 131 as in the present invention is 1: 0.75. When it is less than or equal to the electrical resistance when the carrier collected in the transparent electrode layer 131 moves to the metal electrode layer 135 can be minimized.

So far, the present invention has been described as an example in which each cell of the solar cell module is a single junction module. Alternatively, the present invention is similarly applied to the case where each cell of the solar cell module is a double junction solar cell or a triple junction solar cell. Can be applied.

FIG. 3 is a view for explaining an example in which the photoelectric conversion unit PV of the solar cell module according to the present invention includes a double junction solar cell or a p-i-n-p-i-n structure.

Hereinafter, descriptions of parts overlapping with those described in detail above will be omitted.

As illustrated in FIG. 3, the photoelectric conversion unit PV of the double junction solar cell may include a first photoelectric conversion unit PV1 and a second photoelectric conversion unit PV2.

As shown in FIG. 3, the double junction solar cell has a first p-type semiconductor layer PV1-p, a first i-type semiconductor layer PV1-i, a first n-type semiconductor layer PV1-n, The second p-type semiconductor layer PV2-p, the second i-type semiconductor layer PV2-i, and the second n-type semiconductor layer PV2-n may be sequentially stacked.

The first i-type semiconductor layer PV1-i can mainly absorb light in a short wavelength band to generate electrons and holes.

In addition, the second i-type semiconductor layer PV2-i mainly absorbs light having a longer wavelength band than the short wavelength band to generate electrons and holes.

As described above, a solar cell having a double junction structure can have high efficiency because it absorbs light in a short wavelength band and a long wavelength band to generate a carrier.

In addition, in the thin film solar cell as illustrated in FIG. 3, the first i-type semiconductor layer PV1-i of the first photoelectric conversion unit PV1 includes an amorphous silicon material a-Si, and a second photovoltaic cell. The second i-type semiconductor layer PV2-i of the converter PV2 may include an amorphous silicon material (a-SiGe) containing a germanium material.

In such a double junction solar cell, the plurality of micro lenses 135 as described above with reference to FIGS. 1 and 2A to 2C are included in the second electrode 130, and the plurality of micro lenses 135 are illustrated in FIG. 1. And the same as described in Figures 2a to 2c.

Therefore, a detailed description of the plurality of microlenses 135 applied in the double junction solar cell is the same as described with reference to FIGS. 1 and 2A to 2C, and thus will be omitted.

As described above, even in the dual junction thin film solar cell in which the plurality of micro lenses 135 are included in the second electrode 130, the plurality of micro lenses 135 more efficiently reflect light of medium and long wavelength bands of 700 nm or more. Scattering can further improve the efficiency of the thin film solar cell.

4 is a diagram for explaining an example in which the solar cell module according to the present invention includes a triple junction solar cell or a p-i-n-p-i-n-p-i-n structure.

Hereinafter, the description of the parts overlapping with those described in detail above will be omitted.

As shown in FIG. 4, the photoelectric conversion unit PV of the thin film solar cell includes the first photoelectric conversion unit PV1, the second photoelectric conversion unit PV2, and the third photoelectric conversion unit from the incident surface of the substrate 100. PV3 may be arranged in sequence.

Here, the first photoelectric conversion unit PV1, the second photoelectric conversion unit PV2, and the third photoelectric conversion unit PV3 may be formed in a pin structure, and thus, the first p-type semiconductor layer may be formed from the substrate 100. PV1-p), first intrinsic semiconductor layer PV1-i, first n-type semiconductor layer PV1-n, second p-type semiconductor layer PV2-p, second intrinsic semiconductor layer PV2-i , The second n-type semiconductor layer PV2-n, the third p-type semiconductor layer PV3-p, the third intrinsic semiconductor layer PV3-i, and the third n-type semiconductor layer PV3-p are disposed in this order. Can be.

The first intrinsic semiconductor layer PV1-i, the second intrinsic semiconductor layer PV2-i, and the third intrinsic semiconductor layer PV3-i may be implemented in various ways.

In FIG. 4, as a first example, the first intrinsic semiconductor layer PV1-i includes an amorphous silicon (a-Si) material, and the second intrinsic semiconductor layer PV2-i includes an amorphous material containing germanium (Ge) material. The third intrinsic semiconductor layer PV3-i includes a silicon (a-SiGe) material, and the third intrinsic semiconductor layer PV3-i includes a microcrystal silicon (μc-SiGe) material containing a germanium (Ge) material.

Here, the germanium (Ge) material may be doped with impurities as well as the second intrinsic semiconductor layer PV2-i and the third intrinsic semiconductor layer PV3-i.

Here, the content ratio of germanium (Ge) included in the third intrinsic semiconductor layer PV3-i may be greater than the content ratio of germanium (Ge) included in the second intrinsic semiconductor layer PV2-i. This is because the band gap becomes smaller as the content ratio of germanium (Ge) increases. As the bandgap decreases, it is advantageous to absorb light having a long wavelength.

Therefore, the content of germanium (Ge) included in the third intrinsic semiconductor layer PV3-i is greater than the content ratio of germanium (Ge) included in the second intrinsic semiconductor layer PV2-i. In the semiconductor layer PV3-i, light having a long wavelength may be absorbed more efficiently.

Alternatively, as a second example, the first intrinsic semiconductor layer PV1-i may include an amorphous silicon (a-Si) material, and the second intrinsic semiconductor layer PV2-i and the third intrinsic semiconductor layer ( PV3-i) may include a microcrystalline silicon (μc-Si) material. Here, the band gap of the third intrinsic semiconductor layer PV3-i may be lowered by allowing the germanium (Ge) material to be doped with impurities only in the third intrinsic semiconductor layer PV3-i.

Hereinafter, as shown in FIG. 4, the first example, that is, the first intrinsic semiconductor layer PV1-i and the second intrinsic semiconductor layer PV2-i includes an amorphous silicon (a-Si) material. The ternary semiconductor layer PV3-i includes a microcrystal silicon (μc-Si) material, and the second intrinsic semiconductor layer PV2-i and the third intrinsic semiconductor layer PV3-i are germanium together. It explains on the premise that it contains (Ge) substance.

Here, the first photoelectric conversion unit PV1 may generate power by absorbing light of a short wavelength band, and the second photoelectric conversion unit PV2 may generate power by absorbing light of an intermediate band between a short wavelength band and a long wavelength band. The third photoelectric conversion unit PV3 may generate light by absorbing light having a long wavelength band.

Here, the thickness of the third intrinsic semiconductor layer PV3-i is thicker than the thickness of the second intrinsic semiconductor layer PV2-i, and the thickness of the second intrinsic semiconductor layer PV2-i is the first intrinsic semiconductor layer PV1. thicker than -i).

For example, the first intrinsic semiconductor layer PV1-i may be formed to a thickness of 100 to 150 nm, the second intrinsic semiconductor layer PV2-i may be formed to a thickness of 150 to 300 nm, and the third intrinsic The semiconductor layer PV3-i may be formed to a thickness of 1.5 μm to 4 μm.

This is to further improve the light absorption of the long wavelength band in the third intrinsic semiconductor layer PV3-i.

As described above, in the case of the triple junction solar cell as illustrated in FIG. 4, power generation efficiency may be high because light of a wider band may be absorbed.

In such a triple junction solar cell, a plurality of micro lenses 135 as described above with reference to FIGS. 1 and 2A to 2C are included in the second electrode 130, and the plurality of micro lenses 135 are illustrated in FIG. 1. And the same as described in Figures 2a to 2c.

Therefore, a detailed description of the plurality of microlenses 135 applied to the triple junction solar cell is the same as described with reference to FIGS. 1 and 2A to 2C, and thus the description thereof is omitted.

As described above, even in the triple junction thin film solar cell in which the plurality of micro lenses 135 are included in the second electrode 130, the plurality of micro lenses 135 more efficiently reflect light in the medium and long wavelength bands of 700 nm or more. Scattering can further improve the efficiency of the thin film solar cell.

5A to 5E, a method of manufacturing a thin film solar cell including a plurality of lenses 135 in the second electrode 130 described above will be described.

5A to 5E are diagrams for explaining an example of the method for manufacturing a thin film solar cell according to the present invention.

First, as shown in FIG. 5A, the first electrode 110 is formed on the substrate 100. The first electrode 110 may be a variety of materials such as electroplating, sputtering, evaporation, and low pressure chemical vapor deposition (LPCVD) on the substrate 100. A film forming method can be used.

Thereafter, as illustrated in FIG. 5B, a p-i-n semiconductor layer is sequentially deposited on the first electrode 110 to form a photoelectric conversion unit PV. The photoelectric conversion unit PV may be formed by chemical vapor deposition (CVD), such as plasma enhanced chemical vapor deposition (PECVD).

Thereafter, as illustrated in FIG. 5C, the transparent electrode layer 131 included in the second electrode 130 is formed on the photoelectric conversion part PV. As described above, the transparent electrode layer 131 functions to minimize contact resistance between the photoelectric conversion part PV and the metal electrode layer 135.

The transparent electrode layer 131 is the same as the method of forming the first electrode 110, electroplating, sputtering, evaporation, low pressure chemical vapor deposition (LPCVD) Various film forming methods such as the like may be used.

Thereafter, as illustrated in FIG. 5D, a plurality of micro lenses 135 are formed on the transparent electrode layer 131. As a method of forming the plurality of micro lenses 135, a printing technique may be used at a low temperature, and may be formed in a dot shape. However, the present invention is not limited thereto, and various other methods capable of sticking in the form of dots may be used.

In order to form such a plurality of micro lenses 135, a resin-based material, for example, a paste containing a carbon polymer or glycerin as described above may be used, and the microlens 135 may be controlled by adjusting the viscosity of the paste. The average slope of the curved portion formed on the second surface 135F2 of FIG. For example, when the viscosity of the paste is increased, the average slope of the curved surface formed on the second surface 135F2 of the microlens 135 becomes relatively large, so that the maximum thickness H135 of the lens 135 is relatively large. In contrast, when the viscosity of the paste is lowered, the average slope of the curved surface formed on the second surface 135F2 of the microlens 135 is relatively low, so that the maximum thickness H135 of the microlens 135 is relatively low. Can have a relatively low value.

As described above, according to the present invention, the second electrode 130 includes a plurality of microlenses 135 larger than the size of the unevenness formed in the first electrode 110 to reflect and scatter light in the medium and long wavelength bands of 700 nm or more. Can enhance the effect.

Subsequently, as shown in FIG. 5E, the metal electrode layer 135 is formed on a part of the transparent reflective layer exposed between the second surface 135F2 of the microlens 135 and the microlens 135 to complete the thin film solar cell. You can.

In the thin film solar cell according to the present invention, the microlens 135 larger than the unevenness of the first electrode 110 is included in the second electrode 130, thereby providing the photoelectric conversion part PV during the thin film solar cell manufacturing process. Eliminate possible adverse effects.

For example, when the plurality of micro lenses 135 are formed on the substrate 100 or inside or on the first electrode 110, the lens 135 may be formed when the photoelectric converter PV is formed. A relatively large and steep inclined surface formed by the curved surface of the photoelectric conversion unit PV has a high probability of cracking. In addition, when the lens 135 is formed in the first electrode 110, a high temperature process (for example, the deposition temperature of the first electrode is 300) when the first electrode 110 and the photoelectric conversion unit PV are formed. And the deposition temperature of the photoelectric conversion unit is 150 ° C to 250 ° C. The possibility of the microlens 135 being degraded is very high.

However, when the microlens 135 is formed in the second electrode 130 as described above, the microlens 135 is formed after the photoelectric converter PV is formed, and thus the photoelectric converter PV is formed. There is no possibility that cracks are formed in the inside, and there is no fear that the characteristics of the microlens 135 may be degraded due to the high temperature process during the process of forming the first electrode 110 and the photoelectric conversion unit PV. In addition, since the forming of the metal electrode layer 135 after the forming of the microlens 135 is a low temperature process, the characteristics of the microlens 135 are hardly deteriorated.

In addition, as in the present invention, when the microlens 135 is formed in the second electrode 130, it is not necessary to consider adverse effects on the photoelectric conversion unit PV, so that the width or diameter or the thickness of the microlens 135 may be adjusted. There is an advantage that can be formed freely.

As described above, the thin film solar cell according to the present invention forms a plurality of micro lenses 135 inside the second electrode 130, so that light of medium and long wavelength bands can be more efficiently absorbed by the photoelectric conversion unit PV. The reflection and scattering may be performed, and the structure in which the plurality of micro lenses 135 are formed inside the second electrode 130 may maintain the characteristics of the micro lenses 135 in a manufacturing process. The micro lens 135 may be formed without adversely affecting the photoelectric conversion part PV.

Until now, the photoelectric conversion unit (PV) of the thin film solar cell module has been described as an example of using a silicon (Si) as an example. It may also be applied to other materials, such as CIGS (Copper indium gallium selenide) or cadmium sulfide (CdS), and the photoelectric conversion unit (PV) is a dye molecule, for example, in a porous titanium dioxide (TiO 2 ) Cadmium sulfide (CdS) may contain the adsorbed material, or may include an organic material or a polymer material.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

Claims (20)

Board;
A first electrode disposed on the substrate;
A second electrode disposed on the first electrode; And
And a photoelectric conversion unit disposed between the first electrode and the second electrode and configured to receive light and convert the light into electricity.
The second electrode is a thin film solar cell including a plurality of micro lenses. The method of claim 1,
The second electrode includes a transparent electrode layer containing a light transmissive conductive material and a metal electrode layer containing a light transmissive conductive material,
The plurality of micro lenses are thin film solar cells positioned between the transparent electrode layer and the metal electrode layer, and comprises a light transmissive non-conductive material. The method of claim 2,
The transparent electrode layer is in contact with the photoelectric conversion portion, the metal electrode layer is in contact with the transparent electrode layer and the plurality of micro lenses thin film solar cell. The method of claim 1,
The plurality of micro lenses is a thin film solar cell including a resin-based material. The method of claim 4, wherein
The resin-based material is a thin film solar cell comprising at least one of a polymer or a monomer-based carbon polymer or a monomer or glycerin. The method of claim 2,
The plurality of micro lenses includes a first surface in contact with the transparent electrode layer and a second surface in contact with the metal electrode layer,
The second surface is a thin film solar cell comprising a curved surface. The method according to claim 6,
The thin film solar cell of the first surface of the plurality of micro lenses comprises a plurality of irregularities. The method of claim 1,
The thin film solar cell having a thickness of an edge portion of the plurality of micro lenses is smaller than a thickness of a central portion. The method of claim 1,
The first electrode includes a plurality of irregularities, and the diameter of at least one of the plurality of micro lenses is greater than a distance between protrusions of the irregularities included in the first electrode. The method of claim 1,
The thin film solar cell having a maximum thickness of at least one of the plurality of micro lenses is greater than a protruding height of irregularities included in the first electrode. The method of claim 1,
A thin film solar cell having a diameter of each of the plurality of micro lenses between 1 μm and 15 μm. The method of claim 1,
The ratio of the maximum thickness of each of the plurality of lenses to the diameter of each of the plurality of micro lenses is 1: 1 to 0.2 to 0.5 thin film solar cell. The method according to claim 6,
The thin film solar cell having a ratio of the total area occupied by the first surfaces of the plurality of micro lenses to the total area of the transparent electrode layer is 1: 0.25 to 0.75. The method of claim 1,
2. The thin film solar cell of claim 2, wherein the two micro lenses positioned in adjacent rows of the plurality of micro lenses are positioned in the same column or in different columns. The method of claim 1,
The plurality of micro lenses includes a first lens formed of a first diameter and a second lens formed of a second diameter smaller than the first diameter. The method of claim 15,
The second lens is a thin film solar cell positioned between the first lens. The method of claim 15,
And the first diameter is between 1.5 times and 2.5 times the second diameter. The method of claim 1,
The photoelectric conversion unit is a thin film solar cell, characterized in that at least one pin structure comprising a P-type semiconductor layer, an intrinsic (i) semiconductor layer, and an n-type semiconductor layer. The method of claim 2,
The transparent electrode layer includes zinc oxide (ZnOx), tin oxide (SnOx), indium oxide (InOx), silicon oxide (SiOx), boron zinc oxide (ZnO: B, BZO) and aluminum zinc oxide (ZnO: Al, AZO). Thin film solar cell comprising at least one material. The method of claim 2,
The thin film solar cell having a thickness of the transparent electrode layer is between 50nm ~ 1.5㎛.
KR1020110115100A 2011-11-07 2011-11-07 Thin film solar cell KR101784440B1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20200043199A (en) * 2018-10-17 2020-04-27 삼성에스디아이 주식회사 Composition for forming electrode for solar cell including nanotextured substrate, electrode prepared using the same and solar cell comprising electrode prepared using the same

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20200043199A (en) * 2018-10-17 2020-04-27 삼성에스디아이 주식회사 Composition for forming electrode for solar cell including nanotextured substrate, electrode prepared using the same and solar cell comprising electrode prepared using the same

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