TWI502754B - Thin film type solar cell and manufacturing method thereof - Google Patents

Description

Thin film type solar cell and manufacturing method thereof

The present invention relates to a thin film type solar cell, and more particularly to a thin film type solar cell having a large light transmitting area, which can be used as a substitute for a glass window in a building.

A solar cell having semiconductor characteristics is used to convert light energy into electrical energy.

The structure and principle of a conventional solar cell will be briefly explained below. The solar cell is formed in a PN-junction structure where a positive (P) type semiconductor forms a junction with a negative (N) type semiconductor. When a solar ray is incident on a solar cell having a PN-junction structure, holes (+) and electrons (-) are generated in the semiconductor due to solar ray energy. With the electric field generated by the PN-junction region, the hole (+) drifts toward the P-type semiconductor, and the electron (-) drifts toward the N-type semiconductor, thereby generating electric energy with the appearance of the potential.

Solar cells can be roughly classified into wafer type solar cells and thin film type solar cells.

A wafer type solar cell uses a wafer made of a semiconductor material such as germanium. At the same time, a thin film type solar cell was produced by forming a thin film type semiconductor on a glass substrate.

Regarding efficiency issues, wafer type solar cells are superior to thin film type solar cells. However, in the example of a wafer type solar cell, it is difficult to achieve a thin thickness because of the difficulty in realizing the manufacturing process. In addition, wafer type solar cells use expensive semiconductor substrates, thereby increasing their manufacturing costs. For wafer type solar cells, where it is difficult to obtain a light transmitting region, a wafer type solar cell cannot be used as a substitute for a glass window in a building.

Meanwhile, although a thin film type solar cell is inferior to a wafer type solar cell in terms of efficiency, a thin film type solar cell has an advantage that, for example, a thin profile can be realized and a low-priced material can be used. Therefore, the thin film type solar cell is suitable for mass production. In addition, since this thin film type solar cell can easily obtain a light transmitting region, a thin film type solar cell can be used as a substitute for a glass window in a building.

A thin film type solar cell of the prior art will be described below with reference to the accompanying drawings.

The "Fig. 1" is a perspective view of a thin film type solar cell of the prior art.

As shown in FIG. 1, a thin film type solar cell of the prior art includes a substrate 10, a plurality of front electrodes 20, a semiconductor layer 30, and a transparent conductive layer 40. At this time, a plurality of front electrodes 20 are formed on the substrate 10 at regular intervals, and then the semiconductor layer 30 and the transparent conductive layer 40 are sequentially formed on the plurality of front electrodes 20. Further, each contact portion 35 and each separation channel 55 are formed in the semiconductor layer 30 and the transparent conductive layer 40. Then, a plurality of rear electrodes 50 are formed on the transparent conductive layer 40. Each of the rear electrodes 50 is electrically connected to the front electrode 20 via the contact portion 35, and a plurality of rear electrodes 50 are formed in accordance with a fixed interval of each separation passage 55, and the separation passage 55 is placed between the rear electrodes 50.

However, when used as a substitute for a glazing in a building, a conventional film type solar cell has the following disadvantages.

In order to use a thin film type solar cell as a substitute for a glazing in a building, it is necessary to obtain a light transmitting region of any size in a thin film type solar cell. Since the thin film type solar cell of the prior art includes the use of the transparent metal front electrode 20 and the use of the opaque metal after the electrode 50, the light transmitting region is limited to the separation channel 55 placed between each of the rear electrodes 50. Therefore, the limited light transmission area in the conventional film type solar cell cannot ensure a wide visible range.

In order to widen the light transmitting region, the width of the separation passage 55 placed between each of the rear electrodes 50 is increased. This approach may cause problems with reduced battery efficiency and increased process time. That is, if the width of the separation passage 55 is increased, the effective area for generating the battery power is reduced by the width increase of the separation passage 55, thereby reducing the battery efficiency. Further, the separation passage 55 is formed by a laser scribing process, whereby the laser scribing process must be repeated to increase the width of the separation passage 55, resulting in a problem that the processing time is too long.

Accordingly, it is an object of the present invention to provide a thin film type solar cell and a method of fabricating the same that substantially obviate one or more of the problems caused by the limitations and disadvantages of the prior art.

An aspect of the present invention provides a thin film type solar cell and a method of fabricating the same that can ensure a wide transparent region without reducing battery efficiency and increasing process time, thereby being used as a substitute for a glazing in a building.

Other advantages, objects, and features of the invention will be set forth in part in the description which follows, It is understood or can be derived from the practice of the invention. The objectives and other advantages of the invention will be realized and attained by the <RTIgt;

In order to obtain these and other features of the present invention, the present invention is embodied and broadly described. A thin film type solar cell comprises: a substrate; a plurality of front electrodes disposed on the substrate at a fixed interval; and a plurality of semiconductor layers therebetween Each of the inserted or separated channels is inserted as a fixed interval, a plurality of semiconductor layers are located on the plurality of front electrodes; and a plurality of rear electrodes are inserted, each of the separate channels being inserted as a fixed interval, and each of the rear electrodes is electrically connected The front electrode, wherein each of the rear electrodes is patterned such that the predetermined portion of the rear electrode includes a light transmitting portion.

According to another aspect of the invention, a method of fabricating a thin film type solar cell includes: forming a plurality of front electrodes on a substrate at a fixed interval; forming a semiconductor layer on an entire surface of the substrate including the plurality of front electrodes; and removing the semiconductor layer through the clear a predetermined portion forming a plurality of contact portions and a separation channel; and patterning a plurality of rear electrodes according to a fixed interval of each separation channel interposed therebetween, wherein each of the rear electrodes is electrically connected to the front electrode through the contact portion, and each of the rear electrodes The light transmitting portion is included to increase the light transmitting region.

According to another aspect of the invention, a method of fabricating a thin film type solar cell includes: forming a plurality of front electrodes on a substrate at regular intervals; forming a semiconductor layer on an entire surface of a substrate including a plurality of front electrodes; and removing a semiconductor layer The predetermined portion forms a plurality of contact portions; the plurality of rear electrodes are patterned according to a fixed interval of each separation channel interposed therebetween, wherein each rear electrode is electrically connected to the front electrode through the contact portion, and each of the rear electrodes includes a light transmitting portion Thereby, the light transmitting region is increased; and when the back electrode is used as a mask, the semiconductor layer is removed from the light transmitting portion and the separating channel.

It is to be understood that the foregoing general description of the invention and the claims

Preferred embodiments of the present invention will now be described in detail in conjunction with the drawings. The same reference numbers are used in the drawings to refer to the same or like parts.

Hereinafter, a thin film type solar cell of the present invention and a method of manufacturing the same will be described with reference to the accompanying drawings.

<Thin film type solar cell>

Fig. 2 is a perspective view showing a thin film type solar cell according to an embodiment of the present invention. Figure 3A is a cross-sectional view taken along line AA of Figure 2, and Figure 3B is a cross-sectional view taken along line BB of Figure 2, and Figure 3C shows It is a sectional view of CC along "Fig. 2".

As shown in FIG. 2, FIG. 3A, FIG. 3B, and FIG. 3C, the thin film solar cell of the embodiment of the present invention includes a substrate 100, a plurality of front electrodes 200, and a semiconductor layer 300. The transparent conductive layer 400 and a plurality of back electrodes 500.

The substrate 100 is formed of glass or transparent plastic.

A plurality of front electrodes 200 are formed on the substrate 100 according to a fixed interval, wherein the front electrode 200 is made of a transparent conductive material such as zinc oxide, boron-doped zinc oxide (ZnO: B), aluminum-doped zinc oxide (ZnO: Al), It is made of tin oxide (SnO2), fluorine-doped tin dioxide (SnO2:F) or indium tin oxide (ITO). The front electrode 200 corresponds to the incident surface of the sun ray. In this regard, it is important for the front electrode to absorb solar rays to the maximum extent to transmit solar radiation to the interior of the solar cell. To this end, the front electrode 200 contains an irregular structure. If the electrode 200 is formed before the irregular structure, the solar radiation reflectance on the solar cell is lowered due to the scattering of the sun rays, and the solar ray absorption ratio in the solar cell is increased, thereby improving the battery efficiency.

A plurality of semiconductor layers 300 are formed over the front electrode 200, wherein a plurality of semiconductor layers 300 are placed at a fixed interval of each of the contact portions 350 or each separation channel 550 interposed therebetween. The semiconductor layer 300 is made of a germanium-based semiconductor material in which the semiconductor layer 300 forms a PIN structure, where a P-type semiconductor layer, an I-type semiconductor layer, and an N-type semiconductor layer are sequentially deposited. In the semiconductor layer 300 having the PIN structure, a depletion region is generated in the I-type semiconductor layer by the P-type semiconductor layer and the N-type semiconductor layer, whereby an electric field occurs therein. Therefore, electrons and holes generated by the solar rays are drifted by the electric field, and the drifting electrons and holes are collected in the N-type semiconductor layer and the P-type semiconductor layer, respectively. If the semiconductor layer 300 having the PIN structure is formed, first, a P-type semiconductor layer is formed on the front electrode 200, and then an I-type and N-type semiconductor layer are preferably formed thereon. This is because the drift mobility of the hole is smaller than the drift mobility of the electron. In order to maximize the collection efficiency of the incident light, a P-type semiconductor layer is provided adjacent to the light incident surface.

As is apparent from the expanded portion of "Fig. 2", the semiconductor layer 300 is formed in a tandem structure in which the first semiconductor layer 310, the buffer layer 320, and the second semiconductor layer 330 are sequentially deposited.

The first semiconductor layer 310 and the second semiconductor layer 330 each form a PIN structure, where a P-type semiconductor layer, an I-type semiconductor layer, and an N-type semiconductor layer are sequentially deposited.

The first semiconductor layer 310 forms a PIN structure of an amorphous semiconductor material, and the second semiconductor layer 330 forms a PIN structure of a microcrystalline semiconductor material.

An amorphous semiconductor material is characterized by absorbing light of a short wavelength, and the microcrystalline semiconductor material is characterized by absorbing light of a long wavelength. The mixing of the amorphous semiconductor material with the microcrystalline semiconductor material enhances the light absorption efficiency, but is not limited to this type of mixing. That is, the first semiconductor layer 310 is formed of an amorphous semiconductor/germanium material or a microcrystalline semiconductor material, and the second semiconductor layer 330 is formed of an amorphous semiconductor material or an amorphous semiconductor/germanium material.

The buffer layer 320 is interposed between the first semiconductor layer 310 and the second semiconductor layer 330, wherein the buffer layer 320 can smooth the drift of electrons and holes by tunnel junctions. The buffer layer 320 is made of a transparent material such as zinc oxide.

The semiconductor layer 300 is formed in a triple structure instead of the series structure. In the example of the three-layer structure, each buffer layer is interposed between each of the first, second, and third semiconductor layers included in the semiconductor layer 300.

A plurality of transparent conductive layers 400 are formed over the semiconductor layer 300, wherein the transparent conductive layer 400 is provided with the same pattern type as the semiconductor layer 300. That is, a plurality of transparent conductive layers 400 are formed at a fixed interval of each contact portion 350 or each separation channel 550 interposed therebetween. The transparent conductive layer 400 is made of a transparent conductive material such as zinc oxide, boron-doped zinc oxide, aluminum-doped zinc oxide, zinc hydroxide doped or silver. The transparent conductive layer 400 can be omitted. However, in order to improve battery efficiency, forming the transparent conductive layer 400 is preferable to omitting the transparent conductive layer 400. This is because the transparent conductive layer 400 enables the solar rays penetrating the semiconductor layer 300 to be diffused at all angles, whereby the solar rays are reflected on the rear electrode 500 and then incident on the semiconductor layer 300 again, thereby improving battery efficiency.

A plurality of contact portions 350 and separation channels 550 are formed by removing predetermined portions of the semiconductor layer 300 and the transparent conductive layer 400. Therefore, the plurality of contact portions 350 and the separation passage 550 are formed at fixed intervals.

Each of the rear electrodes 500 is electrically connected to the front electrode 200 through the contact portion 350, wherein a plurality of rear electrodes 500 are formed at a fixed interval of each of the separation passages 550 interposed therebetween. The rear electrode 500 is made of a metal material such as silver, aluminum, silver + molybdenum, silver + nickel or silver + copper.

Then, a plurality of light transmitting portions 570 are patterned at designated portions of the respective rear electrodes 500. The light transmitting portion 570 corresponds to a portion of the back electrode 500 that is free of metal material. The transparent conductive layer 400 is exposed by the light transmitting portion 570, so that the semiconductor layer 300, the front electrode 200, and the substrate 100 sequentially placed under the exposed transparent conductive layer 400 can transmit solar rays. Finally, the solar rays incident on the substrate 100 from the bottom side of the substrate 100 are transferred by the light transmitting portion 570, whereby the size of the light transmitting region of the solar cell can be increased. If the transparent conductive layer 400 is not formed on the semiconductor layer 300, the semiconductor layer 300 is exposed by the light transmitting portion 570.

As shown in "Fig. 2", the light transmitting portion 570 can form a straight line pattern, but is not limited to such a pattern. The light transmitting portion 570 in the rear electrode 500 may form various patterns. The "4A" and "4B" drawings are a series of plan views showing various patterns of the light transmitting portion 570 of the present invention shown in the "Fig. 2" plan view. As shown in "FIG. 4A", the light transmitting portion 570 can form a curved pattern. As shown in "FIG. 4B", the light transmitting portion 570 can form a letter-shaped pattern. Although not shown in the drawings, the light transmitting portion 570 may also form a pattern of symbol shapes, and may change its shape as necessary.

In the example of the thin film type solar cell of the embodiment of the present invention, the sun ray can penetrate the light transmitting portion 570 and the separation channel 550, and the light transmitting portion 570 can penetrate the sun ray as compared with the prior art, thereby increasing More light transmissive areas. Therefore, the thin film type solar cell of the present invention can obtain a sufficient visual range for use as a substitute for the glazing. In particular, by adjusting the overall size of the light transmitting portion 570, the light transmitting region of the solar cell can be determined. The visual range can be changed as needed. Further, the light transmitting portion 570 forming the letter shape pattern or the symbol shape pattern can also achieve an advertising effect.

Fig. 5 is a perspective view showing a thin film type solar cell according to another embodiment of the present invention. Figure 6A is a cross-sectional view taken along line AA of Figure 5, and Figure 6B is a cross-sectional view taken along line BB of Figure 5, and Figure 6C shows the figure. It is a sectional view of CC along "5th". The transparent conductive layer 540 placed under the exposed transparent conductive layer 400 and the transparent conductive layer 400 exposed by the semiconductor layer 300 are removed from the thin film solar cell of "Fig. 2", and the invention shown in Fig. 5 can be manufactured. In another embodiment of the thin film type solar cell, the thin film type solar cell of "Fig. 5" can further enhance light transmission efficiency. The thin film type solar cell of "Fig. 5" is the same as the thin film type solar cell of "Fig. 2" except for the structure of the light transmitting portion 570. Therefore, the same reference numerals are used in the drawings to indicate the same or similar components of the foregoing embodiments, and the detailed explanation of the same or similar components is omitted.

As shown in FIG. 5, FIG. 6A, FIG. 6B, and FIG. 6C, the thin film solar cell according to another embodiment of the present invention includes a light transmitting portion 570 in the rear electrode 500. Then, the front electrode 200 is exposed by the light transmitting portion 570. Therefore, when the solar ray incident on the substrate 100 from the lower side of the substrate 100 is transmitted by the light transmitting portion 570, the solar ray penetrates only the substrate 100 and the front electrode 200. Therefore, compared with the thin film type solar cell of "Fig. 2", the thin film type solar cell of "Fig. 5" can increase the light transmission efficiency.

The "fifth diagram" indicates that the front electrode 200 is exposed by the light transmitting portion 570 by removing the transparent conductive layer 400 placed in the light transmitting portion 570 and the semiconductor layer 300 placed thereunder, but is not limited thereto. Only the transparent conductive layer 400 placed in the light transmitting portion 570 is removed, and the semiconductor layer 300 can be exposed by the light transmitting portion 570.

<Method of Manufacturing Thin Film Solar Cell>

"7A", "7B", "7C" and "7D" are series of perspective views of a method for manufacturing a thin film type solar cell according to an embodiment of the present invention, relating to "Fig. 2" A method of manufacturing a thin film type solar cell.

First, as shown in "FIG. 7A", a plurality of front electrodes 200 are formed on the substrate 100 at regular intervals.

The forming process of the plurality of front electrodes 200 is composed of the following steps, and zinc oxide and boron-doped zinc oxide are formed on the entire surface of the substrate 100 by sputtering or metal organic chemical vapor deposition (MOCVD). a transparent conductive layer doped with aluminum zinc oxide, tin dioxide, fluorine-doped tin dioxide or indium tin oxide (ITO), and a predetermined portion of the transparent conductive layer removed by laser scribing.

The front electrode 200 corresponds to the incident surface of the sun ray. In this regard, it is important for the front electrode 200 to absorb solar rays to the maximum extent to transmit solar rays to the interior of the solar cell. To this end, the front electrode 200 includes an irregular surface fabricated by a texturing process. The surface of the material layer is provided with an irregular surface, that is, a ruthenium structure, which is an etching process using a photolithography process, an anisotropic etching process using a chemical solution, or a mechanical scribe process. The trench formation process.

Then, as shown in "FIG. 7B", the semiconductor layer 300 and the transparent conductive layer 400 are sequentially formed on the entire surface of the substrate 100.

The semiconductor layer 300 is made of a germanium-based semiconductor material, and the semiconductor layer 300 is formed into a PIN structure or a NIP structure by plasma chemical vapor deposition.

Although not shown in the drawing, as shown in the expanded portion of "Fig. 2", the semiconductor layer 300 may be formed in a series structure by sequentially depositing the first semiconductor layer 310, the buffer layer 320, and the second semiconductor layer 330.

The transparent conductive layer 400 may be made of a transparent conductive material such as zinc oxide, boron-doped zinc oxide, aluminum-doped zinc oxide or silver by sputtering or metal organic chemical vapor deposition. The transparent conductive layer 400 can also be omitted.

As shown in "FIG. 7C", a plurality of contact portions 350 and separation channels 550 are formed by removing predetermined portions of the semiconductor layer 300 and the transparent conductive layer 400. The formation process of the contact portion 350 and the separation channel 550 can be accomplished by laser scoring. The separation passage 550 is formed after the contact portion 350 is formed, the contact portion 350 is formed after the separation passage 550 is formed, or the contact portion 350 and the separation passage 550 are simultaneously formed.

In particular, the contact portion 350 and the separation channel 550 can be simultaneously formed by a laser beam irradiation process, which will be explained below in conjunction with "Fig. 8".

Fig. 8 is a schematic view showing a laser scribing apparatus according to an embodiment of the present invention. As shown in FIG. 8, the laser scribing apparatus of the embodiment of the present invention provides a laser oscillator 600, a first mirror 610, a second mirror 630, a first lens 650, and a second lens 670. When the laser oscillator 600 emits a laser beam, the emitted laser beam is incident on the first mirror 610. In this case, half of the incident laser beam passes through the first mirror 610, and the other half of the incident laser beam is reflected on the first mirror 610. Therefore, the laser beam penetrating the first mirror 610 is applied to the target object via the first lens 650, and the laser beam reflected on the first mirror 610 is passed through the second lens 670 after penetrating the second mirror 630. Apply to the target object. At this time, the second mirror 630 completely reflects the incident laser beam.

Finally, the laser beam emitted by one of the laser oscillators 600 is divided into two different directions of laser beams, that is, two different directions of laser beams can simultaneously form the contact portion 350 and the separation channel 550.

After the formation of the contact portion 350 and the separation channel 550, an additional process may be provided for cleaning the remaining residue in the contact portion 350 and the separation channel 550, as will be described in detail below.

When the contact portion 350 and the separation channel 550 are formed by a laser scribing method, residues containing the semiconductor material may remain in the contact portion 350 and the separation channel 550. This residue causes an increase in contact resistance between the electrodes, thereby reducing battery efficiency. In order to avoid an increase in the contact resistance between the electrodes, after the formation process of the contact portion 350 and the separation channel 550, the cleaning process of the residue remaining in the contact portion 350 and the separation channel 550 is additionally completed.

The residue removal process can be accomplished by a dry etch process or a wet etch process.

The dry etching process can be performed by a reactive ion etching process, a normal piezoelectric slurry process, or a remote plasma process. The dry etching process uses at least one of a fluorine-containing etching gas such as nitrogen trifluoride (NF3) or sulfur hexafluoride (SF6) and a chlorine-containing etching gas such as hydrogen chloride (HCl) or chlorine (Cl2), or may be used in an increase. A gas mixture obtained by an inert gas such as argon (Ar), nitrogen (N2) or compressed dry air (CDA) to the aforementioned fluorine- or chlorine-containing etching gas.

The reactive ion etching process and the normal piezoelectric slurry process may use a fluorine-containing etching gas such as sulfur hexafluoride (SF6), nitrogen trifluoride (NF3), sulfur hexafluoride + nitrogen trifluoride (SF6+NF3), Carbon tetrafluoride (CF4), hexafluoroethane (C2F6), perfluoropropane (C3F8), hexafluorobutadiene (C4F6), octafluorocyclopentene (C5F8), hexafluorobenzene (C6F6) or trifluoro At least one of chlorine (ClF3) and a chlorine-containing etching gas such as chlorine (Cl2), Cl3, ruthenium tetrachloride (SiCl4), chloroform (CHCl3) or hydrogen chloride (HCl). For example, a reactive ion etching process uses a sulfur hexafluoride (SF6) etching gas to remove residues from the generated plasma. The normal piezoelectric slurry process uses nitrogen trifluoride (NF3), sulfur hexafluoride (SF6) or six. The sulfur fluoride + nitrogen trifluoride (SF6 + NF3) etching gas removes the residue by the generated normal piezoelectric slurry.

In particular, the reactive ion etching process uses a gas obtained by adding an inert gas such as argon gas or nitrogen gas to the foregoing etching gas, and the normal piezoelectric slurry process uses a large amount of compressed dry air corresponding to an inexpensive inert gas by adding the aforementioned etching gas ( CDA) or a gas mixture obtained from nitrogen.

The remote plasma process uses ions and radicals to remove residues, wherein an etch gas using nitrogen trifluoride is passed through the plasma to produce ions and free radicals.

The wet etching process uses an etchant to remove residues, wherein the etchant comprises from an alkaline solution such as sodium hydroxide (NaOH), potassium hydroxide (KOH), hydrochloric acid (HCl), nitric acid (NHO3), sulfuric acid (H2SO4), phosphorous acid ( At least one etching material selected from the group consisting of H3PO3), hydrogen peroxide (H2O2), and oxalic acid (C2H2O4).

The transparent conductive layer 400 serves as a mask during the aforementioned etching process. If the transparent conductive layer 400 is omitted, other masks are used during the etching process.

As shown in "Fig. 7D", the rear electrode 500 is patterned to complete the thin film type solar cell of "Fig. 2".

Each of the rear electrodes 500 is electrically connected to the front electrode 200 through the contact portion 350, wherein a plurality of rear electrodes 500 are formed at a fixed interval of each of the separation passages 550 interposed therebetween. In the rear electrode 500, a light transmitting portion 570 is present to increase the light transmitting region.

A plurality of back electrodes 500 can be simultaneously formed by one printing process. That is, by screen printing process, inkjet printing process, gravure printing process, gravure offset printing process, reverse offset printing process , a flexo printing process or a microcontact printing process, the plurality of back electrodes 500 may use a metal paste such as silver, aluminum, silver + molybdenum (Ag+Mo), silver+nickel or silver+ Copper is patterned.

If the back electrode 500 is patterned by a printing method, the process can be simplified and the problem of substrate contamination can be reduced as compared with the patterning method using the laser scribing process. In the case of using a printing method, the number of completions of the cleaning process can be reduced, thereby avoiding contamination of the substrate.

"9A", "9B", "9C", "9D" and "9E" are series of perspectives for manufacturing a thin film solar cell according to another embodiment of the present invention. The figure is a manufacturing method of the thin film type solar cell of "figure 5".

In the example of the thin film type solar cell manufactured by the above-described methods explained in "7A", "7B", "7C" and "7D", the transparent conductive layer 400 is provided by the light transmitting portion 570. It is exposed (if the transparent conductive layer 400 is not formed, the semiconductor layer 300 is exposed by the light transmitting portion 570). However, the thin film type solar cell manufactured by the following methods to be explained in conjunction with "9A", "9B", "9C", "9D" and "9E" is additionally removed. The semiconductor layer 300 and the transparent conductive layer 400 exposed by the light transmitting portion 570 can achieve higher light transmission efficiency. Explanations of the same or similar components as the foregoing embodiments will be omitted below.

First, as shown in "FIG. 9A", a plurality of front electrodes 200 are formed on the substrate 100 at regular intervals.

Then, as shown in "FIG. 9B", the semiconductor layer 300 and the transparent conductive layer 400 are sequentially formed on the entire surface of the substrate 100. The transparent conductive layer 400 can be omitted.

As shown in FIG. 9C, a plurality of contact portions 350 and separation channels 550 are formed by removing predetermined portions of the semiconductor layer 300 and the transparent conductive layer 400.

After the formation process of the contact portion 350 and the separation passage 550, there may be other processes for clearing the remaining residue in the contact portion 350 and the separation passage 550. The residue removal process can be completed by the dry etching process or the wet etching process described above.

As shown in "FIG. 9D", a plurality of rear electrodes 500 are patterned in accordance with a fixed interval of each of the separation passages 550 interposed therebetween, and each of the rear electrodes 500 is electrically connected to the front electrode 200 through the contact portion 350. In order to enhance the light transmitting region, the rear electrode 500 is provided with a light transmitting portion 570.

Next, as shown in the "figure 9E", the thin film type solar cell shown in "figure 5" is completed by removing the transparent conductive layer 400 exposed by the light transmitting portion 570 and the semiconductor layer 300 placed thereunder.

The transparent conductive layer 400 placed in the light transmitting portion 570 and the semiconductor layer 300 placed thereunder are removed together, and the "electrode layer" is the front electrode 200 exposed by the light transmitting portion 570, but is not limited thereto. Alternatively, only the transparent conductive layer 400 placed in the light transmitting portion 570 is removed, and the semiconductor layer 300 is exposed by the light transmitting portion 570.

The cleaning process of the transparent conductive layer 400 and the semiconductor layer 300 exposed by the transparent portion 570 can be completed by a dry etching process. In this case, the transparent conductive layer 400 and the semiconductor layer 300 can be simultaneously removed by controlling the etching gas. On the other hand, the etching gas can be applied twice, whereby the transparent conductive layer 400 is first removed, and then the semiconductor layer 300 is removed.

The etching gas for removing the transparent conductive layer 400 may use at least one of methane (CH4), ethane (C2H6), boron trichloride (BCl3), chlorine (Cl2), argon (Ar), and hydrogen (H2).

The etching gas for removing the semiconductor layer 300 is a fluorine-containing gas, a chlorine-containing gas, or a mixture thereof. At this time, the fluorine-containing gas may be at least one of hexafluoroethane (C2F6), sulfur hexafluoride (SF6), carbon tetrafluoride (CF4), and octafluorocyclobutane (C4F8), and a chlorine-containing gas may be used. At least one of chlorine gas, boron trichloride (BCl3), and antimony tetrachloride (SiCl4).

After the transparent conductive layer 400 and the semiconductor layer 300 are removed by a dry etching process, the substrate 100 from which the transparent conductive layer 400 and the semiconductor layer 300 are removed is processed through a drying process in an oven maintained at a temperature of about 80 to 150 °C. The drying process can be omitted.

After the rear electrode 500 is used as a mask, the cleaning process of the transparent conductive layer 400 and the semiconductor layer 300 exposed by the transparent portion 570 can be completed through a wet etching process.

As shown in FIG. 10A, the wet etching process is completed by immersing the substrate 100 into the predetermined etchant 700 stored in the etching bath 710. As shown in FIG. 10B, the wet etching process is completed by spraying the predetermined etchant 700 onto the substrate 100 using the nozzle 720. In particular, the substrate 100 is transferred using the roller 730, and the method of spraying the etchant 700 onto the substrate 100 as explained in FIG. 10B enables a continuous etching process.

An advantage of the wet etching method compared to a general dry etching method is that the manufacturing cost can be reduced and the yield can be improved by the rapid processing wet etching method.

In order to achieve these advantages of the wet etching process, it is important to meet the optimum conditions of the wet etching process. Through repeated tests, the optimal conditions for the wet etch process can be summarized as follows. In detail, the optimum conditions for the wet etch process are the optimum composition of the etchant, the optimum temperature of the etchant, and the optimum etch processing time period.

First, the optimum composition of the etchant will be explained below. The etchant comprises from sodium hydroxide (NaOH), potassium hydroxide (KOH), hydrochloric acid (HCl), nitric acid (NHO3), sulfuric acid (H2SO4), phosphorous acid (H3PO3), hydrogen peroxide (H2O2), and oxalic acid (C2H2O4). Preferably, at least one of the etching materials selected from the group consisting of. Further, the etching material is diluted with water, whereby an aqueous solution of the etching material can be used as an etchant (if the etching material is in a solid state, the etching material in a solid state is inevitably diluted with water). In this case, the weight ratio of the etching material to water is in the range of 0.1:9.9 to 9.9:0.1. The weight ratio of the etching material to the water is preferably in the range of 1:9 to 9:1.

If the weight ratio of the etching material to water is less than 0.1:9.9 (for example, 0.01:9.99), the etching process is not smooth and the etching processing time period is increased. Meanwhile, if the weight ratio of the etching material to water is more than 9.9:0.1 (for example, 9.99:0.01), it is difficult to dissolve the powdery etching material in water.

The optimum temperature of the etchant and the optimum etching processing time period will be explained below. First, it is preferred that the etchant is preferably maintained at a temperature of from 20 to 200 °C. The etchant is preferably kept at a temperature of 50 to 100 ° C more preferably. If the etching temperature is kept below 20 ° C, the etching process may be unsatisfactory and the etching process time period may be too long. Meanwhile, if the etchant temperature is maintained above 200 ° C, it is difficult to control the degree of etching due to the faster etching progress, resulting in a problem of over etching.

Referring to FIG. 11 , in the case where the rear electrode 500 is used as a mask, the transparent conductive layer 400 and the semiconductor layer 300 are removed from the light transmitting portion 570, and the current electrode 200 is exposed by the light transmitting portion 570 due to The rapid etching process results in an excessive etching range, so that the transparent conductive layer 400 and the semiconductor layer 300 are excessively etched. In addition, the back electrode 500 may also fall off.

The optimum etching treatment time period is preferably about 30 seconds to 10 minutes. Further, the optimum etching treatment time period is preferably from about 2 minutes to 5 minutes. If the etching treatment time period is less than 30 seconds, there is insufficient time to complete the desired etching degree, thereby not increasing the light transmitting region. Meanwhile, if the etching treatment time period is more than 10 minutes, it is understood that the transparent conductive layer 400 and the semiconductor layer 300 are excessively etched, and the rear electrode 500 is peeled off in conjunction with the explanation of "11th".

"12A", "12B", "12C", "12D" and "12E" are series of perspectives for manufacturing a thin film solar cell according to another embodiment of the present invention. The figure is a manufacturing method of the thin film type solar cell of "figure 5". The explanation of the same or similar components of the foregoing embodiments is omitted below.

First, as shown in "Fig. 12A", a plurality of front electrodes 200 are formed on the substrate 100 at regular intervals.

Then, as shown in "FIG. 12B", the semiconductor layer 300 and the transparent conductive layer 400 are sequentially formed on the entire surface of the substrate 100. The transparent conductive layer 400 can be omitted.

As shown in FIG. 12C, a plurality of contact portions 350 are formed by removing the predetermined portions of the semiconductor layer 300 and the transparent conductive layer 400. The forming process of the contact portion 350 can be completed by a laser scoring method.

In another embodiment of the present invention, when the contact portion 350 is formed in the semiconductor layer 300 and the transparent conductive layer 400, a separation channel is not formed (refer to "550" of Fig. 9C). Therefore, the forming process of the separation passage 550 is omitted, thereby reducing the number of uses of the laser scribing device and simplifying the process.

After the formation process of the contact portion 350, other processes may exist for cleaning the remaining residue in the contact portion 350. The residue removal process can be completed by the dry etching process or the wet etching process described above.

As shown in "Fig. 12D", the rear electrode 500 is patterned in accordance with a fixed interval of each separation channel 550 interposed therebetween, wherein each rear electrode is electrically connected to the front electrode 200 through the contact portion 350. In order to increase the light transmitting area, the rear electrode 500 is provided with a light transmitting portion 570.

As shown in FIG. 12E, in the case where the rear electrode 500 is used as a mask, the transparent conductive layer 400 placed in the light transmitting portion 570 and the semiconductor layer 300 placed thereunder are removed together, whereby the front electrode 200 is transparent The light portion 570 is exposed. Since the rear electrode 500 is used as a mask, the transparent conductive layer 400 located in the separation channel 550 and the semiconductor layer 300 located thereunder are removed, so that the front electrode 200 is exposed by the separation channel 550. Therefore, the film type solar cell of "Fig. 5" is completed.

The cleaning process of the transparent conductive layer 400 and the semiconductor layer 300 underneath is completed by the dry etching process or the wet etching process described above.

Therefore, the thin film type solar cell of the present invention and the method of manufacturing the same have the following advantages.

In the thin film type solar cell of the present invention, the light transmitting portion is patterned in the rear electrode, whereby the solar rays are transmitted through the light transmitting portion. The light-transmissive region obtained by the thin-film type solar cell of the present invention can obtain a sufficient visible range as a substitute for a glazing as compared with a conventional film-type solar cell.

In the thin film type solar cell of the present invention, the back electrode is patterned in various aspects using a printing process. Compared with the prior art method of using the laser scribing process, the method of the present invention can achieve process simplification by using a printing process, and can also avoid contamination of the substrate. Since the back electrode is patterned by the printing method, the entire size of the light transmitting portion can be easily controlled. Therefore, if necessary, the visible range can be appropriately controlled by changing the light transmitting portion of the solar cell to a desired range.

By removing the transparent conductive layer and the semiconductor layer, the front electrode is exposed by the light transmitting portion, and when the solar ray incident from the lower side of the substrate to the substrate penetrates the light transmitting portion, only the substrate and the front electrode are penetrated, thereby realizing the sun ray High light transmittance.

Although the present invention has been disclosed above in the foregoing embodiments, it is not intended to limit the invention. It is within the scope of the invention to be modified and modified without departing from the spirit and scope of the invention. Please refer to the attached patent application for the scope of protection defined by the present invention.

10. . . Substrate

20. . . Front electrode

30. . . Semiconductor layer

35. . . Contact

40. . . Transparent conductive layer

50. . . Rear electrode

55. . . Separation channel

100. . . Substrate

200. . . Front electrode

300. . . Semiconductor layer

310. . . First semiconductor layer

320. . . The buffer layer

330. . . Second semiconductor layer

350. . . Contact

400. . . Transparent conductive layer

500. . . Rear electrode

550. . . Separation channel

570. . . Translucent part

600. . . Laser oscillator

610. . . First mirror

630. . . Second mirror

650. . . First lens

670. . . Second lens

700. . . Etchant

710. . . Etch tank

720. . . nozzle

730. . . Wheel

Figure 1 is a perspective view of a conventional thin film type solar cell;

2 is a perspective view of a thin film type solar cell according to an embodiment of the present invention;

Fig. 3A is a cross-sectional view taken along line AA shown in Fig. 2, Fig. 3B is a cross-sectional view taken along line BB shown in Fig. 2, and Fig. 3C is shown in Fig. 2 a cross-sectional view of CC;

4A and 4B are a series of plan views of various patterns of the light transmitting portion of the present invention;

Figure 5 is a perspective view showing a thin film type solar cell according to another embodiment of the present invention;

Fig. 6A is a cross-sectional view taken along line AA shown in Fig. 5, Fig. 6B is a cross-sectional view taken along line BB shown in Fig. 5, and Fig. 6C is shown in Fig. 5 a cross-sectional view of CC;

7A to 7D are a series of perspective views showing a method of manufacturing a thin film type solar cell according to an embodiment of the present invention;

Figure 8 is a schematic view of a laser scoring apparatus according to an embodiment of the present invention;

9A to 9E are perspective views showing a series of manufacturing methods of a thin film type solar cell according to another embodiment of the present invention;

10A and 10B are schematic views showing a wet etching method according to various embodiments of the present invention;

Figure 11 is a cross-sectional view of the over-etching that occurs during the wet etch process;

12A to 12E are perspective views showing a series of manufacturing methods of a thin film type solar cell according to another embodiment of the present invention.

100. . . Substrate

200. . . Front electrode

300. . . Semiconductor layer

310. . . First semiconductor layer

320. . . The buffer layer

330. . . Second semiconductor layer

350. . . Contact

400. . . Transparent conductive layer

500. . . Rear electrode

550. . . Separation channel

570. . . Translucent part

Claims (13)

A method of manufacturing a thin film type solar cell, comprising: forming a plurality of front electrodes on a substrate according to a fixed interval; forming a semiconductor layer on an entire surface of one of the substrates including the front electrodes; after forming the semiconductor layer, Forming a transparent conductive layer on the semiconductor layer; removing a predetermined portion of the semiconductor layer and the transparent conductive layer to form a plurality of contact portions and separation channels; and printing a plurality of back electrodes according to a fixed interval of each separation channel interposed therebetween Each of the rear electrodes is electrically connected to the front electrode through the contact portion, and each of the rear electrodes includes a light transmitting portion, thereby adding a light transmitting region, wherein the rear electrodes are formed to expose the transparent conductive layer a region in which the light transmitting portion and the separation channel are to be formed; and in a case where the rear electrode is used as a mask, the light transmitting portion and the semiconductor layer and the transparent conductive layer in the separating channel are removed, wherein After the semiconductor layer and the transparent conductive layer are removed, the transparent conductive layer has the same pattern as the semiconductor layer. The method for manufacturing a thin film type solar cell according to claim 1, wherein the process of removing the transparent conductive layer and the semiconductor layer from the transparent portion is completed by a dry etching process. The method for producing a thin film type solar cell according to claim 2, wherein methane (CH ₄ ), ethane (C ₂ H ₆ ), boron trichloride (BCl ₃ ), chlorine (Cl ₂ ), argon is used. At least one of gas (Ar) and hydrogen (H ₂ ), the dry etching process for removing the transparent conductive layer from the light transmitting portion; using at least one gas containing a fluorine-containing gas, a chlorine-containing gas, or a mixture thereof And completing the dry etching process of removing the semiconductor layer from the light transmitting portion. The method of manufacturing a thin film type solar cell according to claim 1, wherein the cleaning process for removing the transparent conductive layer and the semiconductor layer from the light transmitting portion is performed by a wet etching process. The method of manufacturing a thin film type solar cell according to claim 4, wherein the wet etching process is performed using an etchant comprising sodium hydroxide (NaOH), potassium hydroxide (KOH), hydrochloric acid (HCl). And at least selected from the group consisting of nitric acid (NHO ₃ ), sulfuric acid (H ₂ SO ₄ ), phosphorous acid (H ₃ PO ₃ ), hydrogen peroxide (H ₂ O ₂ ), and oxalic acid (C ₂ H ₂ O ₄ ) An etch material. The method of manufacturing a thin film type solar cell according to claim 5, wherein the etchant is maintained at a temperature of 20 to 200 °C. The method of manufacturing a thin film type solar cell according to claim 5, wherein the wet etching process is completed by immersing the substrate into the etchant or spraying the etchant onto the substrate. The method for manufacturing a thin film type solar cell according to claim 1, wherein the laser beam emitted by the laser oscillator is divided into a plurality of laser beams in a plurality of directions, and the contact is completed by using a laser beam irradiation. The forming process of the portion and the separation channel, so that the contact portion and the separation channel are simultaneously formed. The method for manufacturing a thin film type solar cell according to claim 1, further comprising: etching to remove residue from the contact portion and the separation channel after the forming process of the contact portion and the separation channel. The method for fabricating a thin film type solar cell according to claim 1, wherein the forming process of the semiconductor layer is completed by sequentially depositing a first semiconductor layer, a buffer layer and a second semiconductor layer. A method of manufacturing a thin film type solar cell, comprising: forming a plurality of front electrodes on a substrate according to a fixed interval; forming a semiconductor layer on an entire surface of one of the substrates including the plurality of front electrodes; after forming the semiconductor layer, Forming a transparent conductive layer on the semiconductor layer; forming a plurality of contact portions by removing the predetermined portion of the semiconductor layer and the transparent conductive layer; a plurality of rear electrodes are patterned according to a fixed interval of each separation channel interposed therebetween, wherein Each of the rear electrodes is electrically connected to the front electrode through the contact portion, and each of the rear electrodes includes a light transmitting portion, thereby increasing a light transmitting region, wherein the rear electrodes are formed through a printing process to expose the transparent conductive layer. a region where the light transmitting portion and the separation channel are to be formed; and when the back electrode is used as a mask, the semiconductor layer and the transparent conductive layer are removed from the light transmitting portion and the separation channel, wherein the semiconductor layer is removed and The transparency The transparent conductive layer after the conductive layer has the same pattern as the semiconductor layer. The method for manufacturing a thin film type solar cell according to claim 11, further comprising: etching to remove residue from the contact portion after the forming process of the contact portion. The method for fabricating a thin film type solar cell according to claim 11, wherein a first semiconductor layer, a buffer layer and a second semiconductor layer are sequentially deposited to complete the formation process of the semiconductor layer.