KR101719705B1 - Schottky solar cell and method for manufacturing the same - Google Patents

Schottky solar cell and method for manufacturing the same Download PDF

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KR101719705B1
KR101719705B1 KR1020100051096A KR20100051096A KR101719705B1 KR 101719705 B1 KR101719705 B1 KR 101719705B1 KR 1020100051096 A KR1020100051096 A KR 1020100051096A KR 20100051096 A KR20100051096 A KR 20100051096A KR 101719705 B1 KR101719705 B1 KR 101719705B1
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nanostructures
substrate
conductor
conductive layer
providing
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KR1020100051096A
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KR20110131588A (en
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이정호
지상원
엄한돈
박광태
정진영
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한양대학교 산학협력단
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    • 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
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    • Y02E10/50—Photovoltaic [PV] energy

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Abstract

The present invention relates to a Schottky solar cell and a manufacturing method thereof. The Schottky solar cell comprises i) a substrate, ii) a plurality of first nanostructures located on the substrate and extending in a direction crossing the plate surface of the substrate, iii) a plurality of first nanostructures And iv) an oxide layer provided on at least one surface selected from the group consisting of a surface of the first nanostructures and a surface of the second nanostructures, and v) a conductive layer provided on the oxide layer do. The first nanostructures and the second nanostructures each include a semiconductor material, and the average width of the cross section of the first nanostructure, which is one of the plurality of first nanostructures, in a direction parallel to the surface of the substrate, The second nanostructure of one of the two nanostructures is smaller than the average width of the cross section cut in a direction parallel to the surface of the substrate.

Description

[0001] SCHOTTKY SOLAR CELL AND METHOD FOR MANUFACTURING THE SAME [0002]

The present invention relates to a Schottky solar cell and a manufacturing method thereof. More particularly, the present invention relates to a solar cell using a schottky junction and a method of manufacturing the same.

In recent years, research and development of clean energy has been actively carried out due to resource depletion and rising resource prices. Examples of clean energy include solar energy, wind energy, and tidal energy. In particular, research and development of solar cells have been continuously carried out in order to utilize solar energy efficiently.

Solar cells are devices that convert solar light energy into electrical energy. When sunlight is irradiated on a solar cell, electrons and holes are generated inside the solar cell. The generated electrons and holes move to the P and N poles included in the solar cell, and all the positions are generated between the P and N poles, and the current flows.

And to provide a large-area Schottky solar cell which can be manufactured at low cost and at low cost. It is also intended to provide a method for manufacturing the above-described Schottky solar cell.

A Schottky solar cell according to an embodiment of the present invention includes a substrate, ii) a plurality of first nanostructures disposed on the substrate and extending in a direction intersecting the surface of the substrate and spaced apart from each other, iii) , A plurality of second nanostructures spaced apart from the plurality of first nanostructures, iv) an oxide film provided on at least one surface selected from the group consisting of surfaces of the first nanostructures and surfaces of the second nanostructures, and v ) Oxide film. The first nanostructures and the second nanostructures each include a semiconductor material, and the average width of the cross section of the first nanostructure, which is one of the plurality of first nanostructures, in a direction parallel to the surface of the substrate, The second nanostructure of one of the two nanostructures is smaller than the average width of the cross section cut in a direction parallel to the surface of the substrate.

The Schottky solar cell according to an embodiment of the present invention may further include a reflective film provided on the conductive layer, and the reflective film may include one or more metals selected from the group consisting of copper and gold. The conductive layer may comprise nickel. The Schottky solar cell according to an embodiment of the present invention further includes a transparent conductive layer provided under the substrate, wherein the light transmittance of the transparent conductive layer is larger than the light transmittance of the conductive layer, To the conductive layer. The light transmittance of the transparent conductive layer may be 90% to 99% greater than the light transmittance of the conductive layer.

The oxide film may include SiO 2 , and the thickness of the oxide film may be 1 nm to 2 nm. The Schottky solar cell according to an embodiment of the present invention may further include a semiconductor layer provided between the substrate and the transparent conductive layer.

The upper portion of the second nanostructure may comprise i) an upper surface directly contacting the conductive layer, and ii) an upper surface connected to the upper surface, surrounding the edge of the upper surface and in direct contact with the oxide film. The second nanostructures may have a wall shape and the upper surface may be substantially parallel to the plate surface of the substrate.

The substrate, the plurality of first nanostructures, and the plurality of second nanostructures may be integrally formed. The average height of the plurality of second nanostructures may be greater than the average height of the plurality of first nanostructures.

A Schottky solar cell according to another embodiment of the present invention comprises: i) a first conductor, ii) a semiconductor layer located on the first conductor, iii) a semiconductor layer located on the semiconductor layer and extending in a direction crossing the plate surface of the semiconductor layer A plurality of nanostructures spaced apart from each other, iv) an oxide film provided on the plurality of nanostructures, v) a second conductor covering the oxide film, and vi) a cover layer covering the second conductor. The light transmittance of the first conductor is greater than the light transmittance of the second conductor and the average width of one or more of the plurality of nanostructures becomes smaller as the distance from the first conductor is increased.

The light transmittance of the first conductor may be 90% to 99% greater than the light transmittance of the second conductor. The substrate and the plurality of nanostructures may be integrally formed. The second conductor may comprise nickel.

A method of manufacturing a Schottky solar cell according to an embodiment of the present invention includes the steps of: i) providing a base material; ii) etching the base material to provide a substrate, a plurality of first nanostructures, and a plurality of second nanostructures , iii) providing an oxide film on at least one surface selected from the group consisting of a surface of a plurality of first nanostructures and a surface of a plurality of second nanostructures, and iv) a plurality of first nanostructures and a plurality of second nanostructures And providing a conductive layer over the nanostructures. In the step of providing the substrate, the plurality of first nanostructures, and the plurality of second nanostructures, the first nanostructure of one of the plurality of first nanostructures is divided into an average width of the cross section cut in a direction parallel to the plate surface of the substrate Is smaller than the average width of the cross section of the second nanostructure of one of the plurality of second nanostructures in the direction parallel to the plate surface of the substrate.

A method of manufacturing a Schottky solar cell according to an embodiment of the present invention may further comprise the steps of: i) providing a semiconductor layer under the substrate; and ii) providing a transparent conductive layer under the semiconductor layer . The method of manufacturing a Schottky solar cell according to an embodiment of the present invention may further include providing a reflective layer on the conductive layer, and the reflective layer may include at least one metal selected from the group consisting of copper and gold. In the step of providing the conductive layer, the conductive layer may comprise nickel.

A method of manufacturing a Schottky solar cell according to an embodiment of the present invention includes the steps of i) providing a resin layer between a plurality of first nanostructures and a plurality of second nanostructures after providing an oxide film, ii) Removing the oxide film on the upper surface of the stratum and the plurality of second nanostructures to externally expose the upper surface of the at least one second nanostructure of the plurality of second nanostructures, and iii) removing the resin layer . In providing the plurality of first nanostructures and the plurality of second nanostructures, the average height of the plurality of second nanostructures may be greater than the average height of the plurality of first nanostructures.

A method of manufacturing a Schottky solar cell according to another embodiment of the present invention includes the steps of: i) providing a substrate and a plurality of mutually spaced nanostructures located on the substrate, ii) providing an oxide film on the plurality of nanostructures, iii) Iv) providing a cover layer covering the conductor, v) separating the substrate, vi) providing a semiconductor layer under the plurality of nanostructures, and vii) ) Providing a further conductor having a light transmittance below the light transmittance of the conductor below the semiconductor layer.

In providing the conductor, the light transmittance of the conductor may be 90% to 99% greater than the light transmittance of the other conductor. In the step of providing a plurality of nanostructures spaced apart from each other on the substrate and the substrate, at least one of the nanostructures of the plurality of nanostructures may be provided with a gradually decreasing width from the first conductor.

A solar cell having excellent photoelectric conversion efficiency can be manufactured by using a Schottky phenomenon. Further, since the solar cell is manufactured by separating the resin fixing layer from the substrate, the substrate can be recycled. In addition, the solar cell can be easily manufactured using the electroless etching method.

1 is a schematic cross-sectional view of a solar cell according to a first embodiment of the present invention.
2 is a schematic flow chart showing a method of manufacturing the solar cell of FIG.
FIGS. 3 to 13 are views showing the manufacturing method of the solar cell of FIG. 1 in order.
14 is a schematic cross-sectional view of a solar cell according to a second embodiment of the present invention.
15 is a schematic cross-sectional view of a solar cell according to a third embodiment of the present invention.
16 is a schematic flowchart showing a manufacturing method of the solar cell of FIG.
17 to 23 are views showing the manufacturing method of the solar cell of FIG. 15 in order.

If any part is referred to as being "on" another part, it may be directly on the other part or may be accompanied by another part therebetween. In contrast, when referring to a part being "directly above" another part, no other part is interposed therebetween.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms as used herein include plural forms as long as the phrases do not expressly express the opposite meaning thereto. Means that a particular feature, region, integer, step, operation, element and / or component is specified, and that other specific features, regions, integers, steps, operations, elements, components, and / And the like.

Terms representing relative space, such as "below "," above ", and the like, may be used to more easily describe the relationship to another portion of a portion shown in the figures. These terms are intended to include other meanings or acts of the apparatus in use, as well as intended meanings in the drawings. For example, when inverting a device in the figures, certain parts that are described as being "below" other parts are described as being "above " other parts. Thus, an exemplary term "below" includes both up and down directions. The device can be rotated 90 degrees or rotated at different angles, and the term indicating the relative space is interpreted accordingly.

Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Commonly used predefined terms are further interpreted as having a meaning consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or very formal meanings unless defined otherwise.

The Schottky solar cell used below means a solar cell using a Schottky junction. The Schottky junction signifies a junction of a semiconductor and a structure in rapid contact. In the Schottky junction, a current flows in the forward direction, but no current flows in the reverse direction. Therefore, the Schottky solar cell is interpreted to include all of the solar cells using the above-described principle.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out 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.

1 shows a schematic cross-sectional structure of a solar cell 100 according to a first embodiment of the present invention. The cross-sectional structure of the solar cell 100 of FIG. 1 is merely for illustrating the present invention, and the present invention is not limited thereto. Therefore, the cross-sectional structure of the solar cell 100 can be modified into another form.

1, a solar cell 100 includes a substrate 10, a plurality of nanostructures 20, an oxide film 30, a conductive layer 40, and a reflective film 42. [ In addition, the solar cell 100 may further include other necessary elements. For example, the solar cell 100 further includes a semiconductor layer 50 and a transparent conductive layer 44 formed under the substrate 10. The semiconductor layer 50 is located between the substrate 10 and the transparent conductive layer 44. The photoelectric conversion efficiency of the solar cell 100 can be increased by doping the semiconductor layer 50 with a high concentration of n-type to improve the transport efficiency of holes.

1, the plurality of nanostructures 20 includes first nanostructures 201 and second nanostructures 203. The space between the first nanostructures 201 and the second nanostructures 203 may be filled with a conductor or the like capable of emptying or blocking light. As shown by the arrows in Fig. 1, since light is incident from below, the light utilization efficiency can be maximized by totally reflecting the light using the reflective film 42. [ Although not shown in FIG. 1, the reflection film 42 is connected to the outside to supply power to the passive elements.

As shown in FIG. 1, the solar cell 100 includes first nanostructures 201 and second nanostructures 203 having different structures from each other. Here, although the second nanostructures 203 are integrally connected to each other, the second nanostructures 203 may be divided into a plurality of second nanostructures 203. Further, the second nanostructure 203 may be regarded as one. Accordingly, the solar cell 100 has a combination of the advantages of the first nanostructures 201 and the second nanostructures 203. For example, the first nanostructures 201 have a conical shape and the second nanostructures 203 have a wall shape. Therefore, the durability of the solar cell 100 can be increased by increasing the photoelectric conversion efficiency by using the first nanostructures 201 and supporting the solar cell 100 through the second nanostructures 203. As a result, the solar cell 100 having excellent efficiency and durability can be manufactured.

As shown in FIG. 1, the first nanostructures 201 and the second nanostructures 203 are formed integrally with the substrate 10. For example, the first nanostructures 201, the second nanostructures 203, and the substrate 10 can all be made of n-type silicon. Thus, the first nanostructures 201, the second nanostructures 203, and the substrate 10 form a conformal doping concentration gradient with the semiconductor layer 50. As a result, the photoelectric conversion efficiency of the solar cell 100 can be greatly increased by lowering the energy band gap.

On the other hand, a plurality of nanostructures 20, an oxide film 30, and a conductive layer 40 may be sequentially formed to maximize a space charge region (SCR). Here, as the conductive layer 40, Schottky metal is used. As the Schottky metal, a compound including nickel can be used. For example, polycrystalline NiSi 2 produced by metal induced crystallization due to mutual reaction with a plurality of nanostructures 20 made of a silicon material can be used as the material of the conductive layer 40. The current density J sc of the solar cell 100 can be increased by increasing the impurity region through the conductive layer 40.

The open-circuit voltage (V oc ) can be increased by using the oxide film (30). That is, the potential difference between the both ends of the solar cell 100 when light is received in a state where the circuit is opened can be increased. The oxide film 30 is made of a material containing SiO 2 or the like. Here, the thickness of the oxide film 30 may be 1 nm to 2 nm. When the thickness of the oxide film 30 is too small, it is difficult to increase the open-circuit voltage of the solar cell 100. In addition, when the thickness of the oxide film 30 is too large, it is difficult for holes or electrons to smoothly pass through the oxide film 30. Therefore, the thickness of the oxide film 30 can be adjusted within the above-mentioned range, so that tunneling of holes or electrons can be performed if necessary.

The oxide film 30 prevents a large number of charges present on the surface of the nanostructures 20 from recombining and disappearing. That is, the oxide layer 30 passivates the nanostructures 20 to allow the holes or electrons generated in the nanostructures 20 to be transmitted to the conductive layer 40 without being lost. For this, the oxide film 30 can be tunneled.

On the other hand, as the material of the reflective film 42, a metal containing Cu or Au can be used. For example, a Cu / Al alloy is used as the material of the reflective film 42. The reflective film 42 transmits the electromotive force generated from the conductive layer 40 to an external passive element to drive the passive element. In addition, since the reflective film 42 is formed of an opaque material, loss of light incident from the lower portion of the solar cell 100 can be minimized. As a result, the light absorption rate of the solar cell 100 can be maximized. Here, the light transmittance of the reflective film 42 may be substantially 0%.

In contrast, since the transparent conductive layer 44 must transmit light, a transparent material such as ITO (indium tin oxide) can be used. For example, the light transmittance of the transparent conductive layer 44 may be 90% or more and less than 100%. When the light transmittance of the transparent conductive layer 44 is too low, the transparent conductive layer 44 blocks light and the light absorption rate of the solar cell 100 is lowered. On the other hand, it is difficult to obtain a material having a light transmittance of 100%.

Therefore, the light transmittance of the transparent conductive layer 44 is larger than that of the reflective film 42. For example, the light transmittance of the transparent conductive layer 44 may be 90% to 99% greater than the light transmittance of the reflective film 42. When the difference between the light transmittance of the transparent conductive layer 44 and the light transmittance of the reflective film 42 is too small, the light absorptivity of the solar cell 100 is greatly lowered. In addition, it is difficult for the difference in the light transmittance of the reflective film 42 and the light transmittance of the conductive layer 44 to exceed 99%. Therefore, the difference between the light transmittance of the transparent conductive layer 44 and the light transmittance of the reflective film 42 is maintained within the above-described range. Although not shown in Fig. 1, the transparent conductive layer 44 is connected to the lead electrode 93 (shown in Fig. 15) and the lead wiring 97 (shown in Fig. 15) To an external passive element (not shown).

The width w201 of the first nanostructure 201 gradually decreases from the transparent conductive layer 44 to the conductive layer 40. [ That is, the width w201 of the first nanostructure 201 has a conical shape gradually decreasing along the + z-axis direction. Therefore, the amount of light incident on the first nanostructure 201 can be maximized through the conical lower surface having a larger area than the top of the cone. As a result, the light utilization efficiency of the solar cell 100 can be increased.

On the other hand, as shown in FIG. 1, the upper portion 2031 of the second nanostructure 203 includes a top surface 2031a and an upper side 2031b. Here, since the oxide layer 30 is not present on the upper surface 2031a, the upper surface 2031a directly contacts the conductive layer 40. [ That is, the upper portion 2031 of the second nanostructure 203 is in contact with the conductive layer 40. The upper surface 2031a is substantially parallel to the plate surface 101 of the substrate 10. That is, both the plate surface 101 and the upper surface 2031a of the substrate 10 are located on the xy plane.

The upper side surface 2031b is connected to the upper surface 2031a and surrounds the edge of the upper surface 2031a. Unlike the upper surface 2031a, the upper side 2031b directly contacts the oxide film 30. [ By using the structure of the second nanostructure 203, the power generated by the nanostructure 20 can be quickly transmitted to the outside. That is, the power is generated through the first nanostructure 201 having a larger number than the second nanostructure 203, and then the upper part 2031 of the second nanostructure 203 in direct contact with the conductive layer 40 The power can be quickly supplied to the outside. As a result, the photoelectric conversion efficiency of the solar cell 100 can be greatly increased.

FIG. 2 schematically shows a flowchart of the manufacturing process of the solar cell 100 of FIG. 1, and FIGS. 3 to 13 are views schematically showing steps of the manufacturing process of the solar cell 100 of FIG. Hereinafter, the manufacturing process of the solar cell 100 will be described in order with reference to FIG. 2 and FIG. 3 to FIG.

First, in step S10 of FIG. 2, a base material 12 (shown in FIG. 3) is provided. The base material 12 may be n-type silicon, and the n-type silicon may have a specific crystal orientation. The manufacturing cost of the solar cell can be reduced by using the base material 12 made of a relatively low-cost material, and the solar cell can be made large-sized.

Next, in step S20 of FIG. 2, a mask layer 90 (shown in FIG. 4) provided with openings 901 on the base material 12 is provided. A photoresist layer (not shown) is formed on the base material 12 and then exposed and etched in a predetermined pattern to form openings 901 in the mask layer 90. As shown in Fig. 4, a plurality of openings 901 are formed.

In step S30 of FIG. 2, nanometer-sized metal particles 92 are provided on the base material 12 exposed through the opening 901. Namely, as shown in FIG. 5, nano metal particles 92 such as silver can be deposited on the base material 12. That is, after putting the base material 12 into the chamber (not shown), the nano metal particles 92 can be deposited on the base material 12 in a physical manner. In addition, silver can be deposited by electroless deposition by supporting the base material 12 in an AgNO 3 + HF solution.

Next, in step S40 of FIG. 2, the base material 12 is etched to provide the substrate 10, the first nanostructures 201, and the second nanostructures 203. That is, as shown in Fig. 6, the base material 12 is electroless-etched according to the induction of the nano-metal particles 92 (shown in Fig. 5). The base material 12 can be supported on the HF + H 2 O 2 solution and etched. In this case, the nano metal particles 92 (shown in FIG. 5) are guided and the underlying base material 12 is etched to have a constant shape. Here, the remaining nano metal particles 92 (shown in Fig. 5) can be removed by supporting the base material 12 on nitric acid. As a result, as shown in FIG. 6, the substrate 10 and the nanostructures 20 can be integrally formed. The second nanostructures 203 of the nanostructures 20 are formed under the mask layer 90 (shown in FIG. 5).

When the base material 12 is etched again with potassium hydroxide solution, conical second nanostructures 203 are formed, and the mask layer 90 is removed. As the base material 12 is etched by the potassium hydroxide solution, the first nanostructures 201 agglomerated by the van der Waals force are easily separated from each other. And the upper ends of the first nanostructures 201 are deformed to be pointed. As a result, the first nanostructures 201 and the second nanostructures 203 having the shape shown in FIG. 6 can be provided. Here, the first nanostructures 201 are formed between the nano-metal particles 90 (shown in FIG. 5).

6, the average width aw201 of the cross section of the first nanostructure 201 cut in the direction parallel to the plate surface 101 of the substrate 10, that is, in the xy plane direction is larger than the average width aw201 of the second nanostructure 203 Is smaller than the average width aw203 of the section cut in the direction parallel to the plate surface 101 of the substrate 10. [ Here, the width is interpreted to include the diameter. The width of the second nanostructure 203 is thicker than that of the first nanostructure 201 to ensure durability of the solar cell 100 (shown in FIG. 1).

Next, in step S50 of FIG. 2, the oxide film 30 is provided on the surface of the plurality of first nanostructures 201 or on the surface of the plurality of second nanostructures 203. The oxide film 30 (shown in FIG. 7) can be manufactured by dry-oxidizing the plurality of first nanostructures 201 and the plurality of second nanostructures 203. The oxide film 30 functions as an insulating layer. An oxide film (30) comprises a SiO 2.

Next, in step S60 of FIG. 2, a resin layer 80 is provided between the plurality of first nanostructures 201 and the plurality of second nanostructures 203. The resin layer 80 (shown in FIG. 8) can be formed by spin-coating a material such as PDMS (polydimethylsiloxane). 8, a plurality of first nanostructures 201 and a plurality of second nanostructures 203 are embedded in the resin layer 80. As shown in FIG.

In step S70 of FIG. 2, the upper surface 801 (shown in FIG. 8) of the resin layer 80 and the oxide film 30 (shown in FIG. 8) on the second nanostructures 203 are removed. 8) of the resin layer 80 because the resin layer 80 is removed to such an extent that the oxide film 30 on the second nanostructures 203 is removed. Can be removed to the bottom. For example, the oxide film 30 on the second nanostructures 203 can be removed through a chemical mechanical polishing (CMP) process or the like. In this case, the average height h203 of the second nanostructure 203 is made larger than the average height h201 of the first nanostructure 201 so that the oxide film of the first nanostructure 201 is not removed. Therefore, only the oxide film 30 on the second nanostructures 203 is removed.

Next, in step S80 of FIG. 2, the resin layer 80 (shown in FIG. 10) is removed by a method such as etching. Therefore, as shown in Fig. 10, the upper surface 2031a of the second nanostructure 203 is exposed to the outside. Therefore, the power generated by the second nanostructure 203 can be efficiently supplied to the outside. That is, although power is generated in all of the first nanostructures 201 and the plurality of second nanostructures 203, the number of the first nanostructures 201 is different from the number of the second nanostructures 201 203, so that power is mainly generated in the plurality of first nanostructures 201, and power generated mainly in the second nanostructures 203 is supplied to the outside.

2, a conductive layer 40 is provided on the first nanostructure 201 and the second nanostructure 203 in step S90. (Shown in FIG. 11), that is, the conductive layer 40 is provided on the oxide film 30. Nickel and the like are electrolessly plated and amorphous Si is deposited by physical vapor deposition (PECVD). The conductive layer 40 can be made of a Ni 2 Si thin film layer by metal induced crystallization. On the other hand, since the upper surface 2031a of the second nanostructure 203 is exposed to the outside, it is in direct contact with the conductive layer 40.

Next, a reflective film 42 is provided on the conductive layer 40 in step S100 of FIG. The reflection film 42 (shown in Fig. 12) is connected to the outside and functions also as an electrode. Here, the reflective film 42 may be made of an opaque conductive material containing copper (Cu), gold (Au), or the like. Therefore, the reflection film 42 prevents the light incident from the bottom from escaping to the outside. As a result, the energy is converted into electric power while trapping light in the first nanostructure 201 and the second nanostructure 203 continuously.

In step S110 of FIG. 2, a semiconductor layer 50 is provided under the substrate 10. Further, in step S120, the transparent conductive layer 44 is continuously provided under the semiconductor layer 50. [ (Shown in FIG. 13) by depositing a semiconductor layer 50 and a transparent conductive layer 44 on the substrate. A material doped with a high concentration can be used as the material of the semiconductor layer 50. As the material of the transparent conductive layer 44, a material having both excellent light transmittance and conductivity can be used. Since the semiconductor layer 50 forms a doping concentration gradient with the first nanostructures 201 and the second nanostructures 203, the energy band gap can be lowered and efficient photoelectric conversion is possible. Further, the transparent conductive layer 44 can absorb light from the bottom without loss of light. The solar cell 100 having excellent photoelectric conversion efficiency (shown in FIG. 1) can be manufactured through the above-described steps S10 to S120.

Fig. 14 shows a schematic cross-sectional structure of a solar cell 200 according to a second embodiment of the present invention. Since the structure of the solar cell 200 of FIG. 14 is similar to that of the solar cell 100 of FIG. 1, the same reference numerals are used for the same parts, and a detailed description thereof will be omitted.

As shown in FIG. 14, in the solar cell 200, the oxide film 32 can be formed on all the surfaces of the second nanostructures 203. In this case, the surface of the second nanostructures 203 does not directly contact the conductive layer 40. Therefore, the first nanostructure 201 and the second nanostructure 203 are both covered with the oxide film 32. Accordingly, the first nanostructure 201 and the second nanostructure 203 are combined with the oxide film 32 and the conductive layer 40 to efficiently convert light energy into electric energy. Since the oxide film 32 has a low Schottky barrier of 0.74 eV or less, it absorbs infrared rays to increase the current density.

15 shows a schematic cross-sectional structure of a solar cell 300 according to a third embodiment of the present invention. The structure of the solar cell 300 of FIG. 15 is only for illustrating the present invention, and the present invention is not limited thereto. Therefore, the structure can be variously modified. The operation concept of the solar cell 300 of FIG. 15 is similar to the operation concept of the solar cell 100 of FIG. 1, so that a detailed description thereof will be omitted.

15, the solar cell 300 includes nano-structures 233, an oxide film 33, a first conductor 73, a second conductor 75, and a cover layer 83 . In addition, the solar cell 300 includes external electrodes 93 and 95 and a lead wiring 97. The lead wiring 97 is connected to an external passive element to supply power generated by the solar cell 300. [

Since the light is incident from the bottom of the solar cell 300, the first conductor 73 is made of a material that transmits light better than the second conductor 75. That is, the light transmittance of the first conductor (73) is larger than that of the second conductor (75). Here, the light transmittance of the first conductor 73 is 90% to 99% greater than the light transmittance of the second conductor 75. Light can be incident through the first conductor 73 without loss of light by keeping the difference between the light transmittance of the first conductor 73 and the light transmittance of the second conductor 75 within the above-described range. Also, by maximizing the reflection of light through the second conductor 75, the amount of light absorbed by the nanostructures 233 can be maximized.

As shown in FIG. 15, the plurality of nanostructures 233 extend in the direction crossing the plate surface 291 of the semiconductor layer 29, that is, in the + z-axis direction. The plurality of nanostructures 233 are embedded in the second conductor 75. The plurality of nanostructures 233 are arranged apart from each other. The width w233 of the nanostructures 233 is gradually reduced toward the + z-axis direction. Therefore, the nanostructures 233 can absorb a large amount of light through a lower portion having a larger cross-sectional area than the upper portion. That is, the incident light is absorbed into the solar cell 300 by the multiple reflection and the scattering effect. The electrons or holes generated in the nanostructures 233 can be used for carrier collection through the second conductor 75 by tunneling the oxide film 33.

An oxide film 33 is provided on the plurality of nanostructures 233. The plurality of nanostructures 233, the oxide film 33, and the second conductor 75 form a Schottky bond to efficiently convert light energy into electric energy.

As shown in FIG. 15, the cover layer 83 covers the second conductor 75. Since the cover layer 83 is made of a material such as resin, it has a flexible characteristic. Therefore, the solar cell 300 is easily bent and easy to grasp due to the cover layer 83.

The external electrodes 93 and 95 are connected to the first conductor 73 and the second conductor 75 to supply power generated from the solar cell 300 to the outside through the lead wiring 97. For this, the external electrodes 93 and 95 are firmly connected to the first conductor 73 and the second conductor 75 by vapor deposition or the like.

Fig. 16 schematically shows a flow chart of the manufacturing process of the solar cell 300 of Fig. 15, and Figs. 17 to 23 are views schematically showing respective steps of the manufacturing process of the solar cell 300 of Fig. Hereinafter, the manufacturing process of the solar cell 300 will be described in order with reference to FIG. 16 and FIG. 17 to FIG.

First, in step S13 of FIG. 16, a substrate 13 and a plurality of nanostructures 233 are provided. 17). A base material made of a relatively inexpensive material is subjected to electroless induction-etching with metal particles and then etched with a potassium hydroxide solution to produce a substrate 13 and a plurality of nano-structures 233 having a conical shape thereon . Therefore, the substrate 13 and the plurality of nanostructures 233 are integrally formed. Here, the plurality of nanostructures 233 may be made of a material such as p-type silicon. Although only the nanostructures 233 having a conical shape are shown in FIG. 1, the nanostructures having a wall shape may be mixed with each other.

Next, in step S23 of FIG. 16, an oxide film 33 is provided on the nanostructures 23. Next, as shown in FIG. The oxide film 33 (shown in FIG. 18) can be manufactured by dry-oxidizing the plurality of nanostructures 233. The oxide film 33 functions as an insulating layer. The oxide film 33 comprises SiO 2.

In the step S33 of FIG. 16, the conductor 75 covering the oxide film 33 is provided. 19, after the conductor 75 is formed, the external electrode 95 is deposited thereon, and the lead wiring 97 is connected to the external electrode 95. As the material of the conductor 75, a metal such as nickel may be used. The conductor 75 supplies electric power to the outside via the external electrode 95 and also functions as a reflection film. Therefore, the light utilization efficiency in the nanostructure 233 can be maximized.

Next, in step S43, a cover layer 83 covering the conductor 75 is provided. The conductor 75 can be embedded in the cover layer 83 by spin coating a resin such as polydimethylsiloxane (PDMS) (see FIG. 20). Since the cover layer 83 is bent well, the cover layer 83 can be easily gripped.

Next, in step S53 of Fig. 16, the substrate 10 is detached. (Shown in FIG. 21), that is, the cover layer 83 is gripped to detach the substrate 10 from the conductor 75. As a result, the substrate 10 can be separated as indicated by an arrow. Here, the separated substrate 10 can be reused to manufacture another solar cell.

In step S63 of FIG. 16, a semiconductor layer 29 is provided under the plurality of nanostructures 233. (Shown in FIG. 22). Here, as the material of the semiconductor layer, a p + type semiconductor material can be used. As a result, a conformal doping concentration gradient is formed between the semiconductor layer 29, the nanostructure 23, the oxide film 33, and the conductor 75, so that the energy band gap can be minimized. Therefore, the photoelectric conversion efficiency of the solar cell 300 (shown in Fig. 15 and the same hereinafter) can be greatly improved.

Next, in step S73 of FIG. 16, another conductor 73 is provided under the semiconductor layer 29. Next, as shown in FIG. (Shown in FIG. 23). Here, another conductor 73 is made of a light-transmitting conductive material, for example indium tin oxide (ITO). As a result, light is not incident on the lower part of the solar cell 300 but enters the interior of the solar cell 300 without loss. In addition, the external electrode 93 may be deposited on another conductor 73, and the outgoing wiring 97 may be connected to supply external electric energy generated by the solar cell 300. The solar cell 300 having excellent photoelectric conversion efficiency can be manufactured through the above-described steps S13 to S73.

It will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the following claims.

10. Substrate 12. Base material
100, 200, 300. Solar cell 101. Plate
20, 201, 203, 233. Nanostructure 2031. Top
2031a. Top surface 2031b. Upper side
29, 50. Semiconductor layer 30, 33. Oxide film
40, 42, 44. Conductive layer 73, 75. Conductor
80. Resin layer 801. Top surface
83. Cover layer 90. Mask layer
92. Metal nanoparticles 901. Openings
95, 97. Outgoing wiring

Claims (24)

Board,
A plurality of first nanostructures located on the substrate and extending in a direction intersecting the surface of the substrate and spaced apart from each other,
A plurality of second nanostructures located on the substrate and spaced apart from the plurality of first nanostructures,
An oxide film provided on at least one surface selected from the group consisting of a surface of the first nanostructures and a surface of the second nanostructures,
The conductive layer provided on the oxide film
/ RTI >
Wherein the first nanostructures and the second nanostructures each include a semiconductor material and the first nanostructure of one of the plurality of first nanostructures has an average width of a cross section cut in a direction parallel to the surface of the substrate Is smaller than the average width of a section of one of the plurality of second nanostructures cut in a direction parallel to the plate surface of the substrate,
The upper portion of the second nano-
An upper surface directly contacting the conductive layer, and
An upper side surface connected to the upper surface and surrounding the edge of the upper surface,
A Schottky solar cell. The method according to claim 1,
And a reflective film provided on the conductive layer, wherein the reflective film comprises at least one metal selected from the group consisting of copper and gold. 3. The method of claim 2,
Wherein the conductive layer comprises nickel. 3. The method of claim 2,
And a transparent conductive layer provided under the substrate, wherein a light transmittance of the transparent conductive layer is larger than a light transmittance of the conductive layer, and a width of the first nanostructures gradually decreases from the transparent conductive layer to the conductive layer Schottky solar cells. 5. The method of claim 4,
Wherein a light transmittance of the transparent conductive layer is 90% to 99% greater than a light transmittance of the conductive layer. The method according to claim 1,
Wherein the oxide film comprises SiO 2 , and the thickness of the oxide film is 1 nm to 2 nm. 5. The method of claim 4,
And a semiconductor layer provided between the substrate and the transparent conductive layer. delete The method according to claim 1,
Wherein the second nanostructures have a wall shape and the upper surface is substantially parallel to the plate surface of the substrate. The method according to claim 1,
Wherein the substrate, the plurality of first nanostructures, and the plurality of second nanostructures are integrally formed. 11. The method of claim 10,
Wherein the average height of the plurality of second nanostructures is greater than the average height of the plurality of first nanostructures. The first conductor
A semiconductor layer positioned over the first conductor,
A plurality of nanostructures located on the semiconductor layer and extending in a direction intersecting the surface of the semiconductor layer and arranged to be spaced apart from each other,
An oxide film provided on the plurality of nanostructures,
A second conductor covering the oxide film, and
The cover layer covering the second conductor
/ RTI >
Wherein a light transmittance of the first conductor is greater than a light transmittance of the second conductor and at least one of the plurality of nanostructures has an average width gradually decreasing from the first conductor, Solar cells. 13. The method of claim 12,
Wherein the light transmittance of the first conductor is 90% to 99% greater than the light transmittance of the second conductor. delete 13. The method of claim 12,
Wherein the second conductor comprises nickel. Providing a base material,
Etching the base material to provide a substrate, a plurality of first nanostructures and a plurality of second nanostructures,
Providing an oxide film on at least one surface selected from the group consisting of a surface of the plurality of first nanostructures and a surface of the plurality of second nanostructures, and
Providing a conductive layer over the plurality of first nanostructures and the plurality of second nanostructures,
Lt; / RTI >
In the step of providing the substrate, the plurality of first nanostructures, and the plurality of second nanostructures, one of the plurality of first nanostructures is cut in a direction parallel to the surface of the substrate, Wherein an average width of one of the plurality of second nanostructures is smaller than an average width of a cross section cut in a direction parallel to the plate surface of the substrate. 17. The method of claim 16,
Providing a semiconductor layer under the substrate, and
Providing a transparent conductive layer under the semiconductor layer
The method comprising the steps of: 17. The method of claim 16,
The method of claim 1, further comprising providing a reflective layer on the conductive layer, wherein the reflective layer comprises at least one metal selected from the group consisting of copper and gold. 19. The method of claim 18,
In the step of providing the conductive layer, the conductive layer includes nickel. 17. The method of claim 16,
Providing a resin layer between the plurality of first nanostructures and the plurality of second nanostructures after providing the oxide film,
Removing the oxide film on the upper surface of the resin layer and the plurality of second nanostructures to externally expose the upper surface of the at least one second nanostructure of the plurality of second nanostructures,
Removing the resin layer
The method comprising the steps of: 21. The method of claim 20,
Wherein a plurality of first nanostructures and a plurality of second nanostructures are provided, wherein an average height of the plurality of second nanostructures is greater than an average height of the plurality of first nanostructures, . Providing a substrate and a plurality of spaced apart nanostructures located on the substrate,
Providing an oxide film on the plurality of nanostructures,
Providing a conductor covering the oxide film,
Providing a cover layer covering the conductor,
Separating the substrate,
Providing a semiconductor layer under the plurality of nanostructures, and
Providing another conductor having a light transmittance lower than the light transmittance of the conductor below the semiconductor layer
≪ / RTI > 23. The method of claim 22,
In the step of providing the conductor, the light transmittance of the conductor is 90% to 99% greater than the light transmittance of the another conductor. 23. The method of claim 22,
Wherein at least one of the nanostructures of the plurality of nanostructures is provided with a Schottky solar cell having a smaller width as the distance from the conductor is smaller, Gt;
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