KR20210111400A - Solar cell - Google Patents

Abstract

A solar cell is disclosed. The solar cell includes a substrate including a first conductivity type region and a second conductivity type region forming a p-n junction with the first conductivity type region; an aluminum oxide layer formed on at least one surface of the substrate; and an electrode connected to the first conductive region or the second conductive region through the aluminum oxide layer. The electrode includes conductive powder and predetermined glass frit.

Description

solar cell {SOLAR CELL}

The present invention relates to a solar cell, and more particularly, to a solar cell capable of implementing low contact resistance and excellent conversion efficiency by forming an electrode including a predetermined glass frit on a passivation layer including an aluminum oxide layer. it's about

Solar cells generate electrical energy by using the photoelectric effect of a p-n junction that converts photons of sunlight into electricity. In a solar cell, a front electrode and a rear electrode are respectively formed on the upper and lower surfaces of a semiconductor wafer or substrate on which a p-n junction is formed. In a solar cell, a photoelectric effect of a p-n junction is induced by sunlight incident on a semiconductor wafer, and electrons generated therefrom provide a current flowing to the outside through an electrode. The electrode of such a solar cell may be formed on the wafer surface by applying, patterning, and firing a paste composition for an electrode.

Conventionally developed solar cell electrode compositions have limitations in increasing solar cell conversion efficiency by lowering contact resistance. Recently, a technology of forming an aluminum oxide layer on the front surface to improve production processability and solar cell conversion efficiency has been developed.

Background art of the present invention is disclosed in Japanese Patent Application Laid-Open No. 2015-144162 and the like.

An object of the present invention is to provide a solar cell including an aluminum oxide layer having low contact resistance and excellent conversion efficiency.

1. According to one aspect, a solar cell is provided. The solar cell may include: a substrate including a first conductivity type region and a second conductivity type region forming a p-n junction with the first conductivity type region; an aluminum oxide layer formed on at least one surface of the substrate; and an electrode connected to the first conductive region or the second conductive region through the aluminum oxide layer. The electrode includes a conductive powder and a glass frit, and the glass frit has a total mole % of lead (Pb), tellurium (Te) and lithium (Li) of 50 to 95 mole %, and calcium (Ca ) and a lead-tellurium-lithium-calcium-silicon-oxide (Pb-Te-Li-Ca-Si-O)-based glass frit having a molar ratio of 1:0.005 to 10 of silicon (Si) may be included.

2. In 1 above, the Pb-Te-Li-Ca-Si-O-based glass frit may contain lead (Pb) oxide in an amount of 0.1 to 60 mol%.

3. In 1 or 2, the Pb-Te-Li-Ca-Si-O-based glass frit may contain tellurium (Te) oxide in an amount of 15 to 70 mol%.

4. In any one of 1 to 3, the Pb-Te-Li-Ca-Si-O-based glass frit may contain lithium (Li) oxide in an amount of 0.1 to 35 mol%.

5. In any one of 1 to 4, the Pb-Te-Li-Ca-Si-O-based glass frit may contain calcium (Ca) oxide in an amount of 0.1 to 15 mol%.

6. In any one of 1 to 5, the Pb-Te-Li-Ca-Si-O-based glass frit may include silicon (Si) oxide in an amount of 0.1 to 30 mol%.

7. The Pb-Te-Li-Ca-Si-O-based glass frit according to any one of 1 to 6 above, wherein the bismuth (Bi), zinc (Zn), sodium (Na), phosphorus (P), germanium (Ge) ), gallium (Ga), silver (Ag), iron (Fe), tungsten (W), magnesium (Mg), molybdenum (Mo), cesium (Cs), niobium (Nb), strontium (Sr), titanium (Ti) ), tin (Sn), indium (In), vanadium (V), barium (Ba), nickel (Ni), copper (Cu), potassium (K), arsenic (As), selenium (Se), cobalt (Co) ), zirconium (Zr), manganese (Mn), aluminum (Al), thallium (Tl), tantalum (Ta), cerium (Ce), and may further include one or more elements of boron (B).

8. In any one of 1 to 7 above, the Pb-Te-Li-Ca-Si-O-based glass frit may further include aluminum (Al) oxide in an amount greater than 0 to 5 mol%.

9. The electrode according to any one of 1 to 8 above, wherein the electrode may be prepared from a composition for forming a solar cell electrode including a conductive powder, a glass frit, and an organic vehicle.

10. In 9 above, the composition comprises 60 to 95 wt% of the conductive powder; 0.1 to 20% by weight of the glass frit; and 1 to 30% by weight of the organic vehicle; may include.

The present invention has the effect of providing a solar cell including an aluminum oxide layer having low contact resistance and excellent conversion efficiency.

1 to 3 schematically show a solar cell according to an embodiment of the present invention.

In this specification, the singular expression includes the plural expression unless the context clearly dictates otherwise.

Like reference numerals refer to like elements throughout. In addition, in describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

When the positional relationship of two parts is described as 'on', 'on', 'on', 'beside', etc., between the two parts unless 'directly' or 'directly' is used. One or more other parts may be located in

In describing the drawings, positional relationships such as 'upper', 'upper surface', 'lower', 'lower surface', etc. are only described with reference to the drawings, and do not represent absolute positional relationships. That is, the positions of 'upper' and 'lower' or 'upper surface' and 'lower surface' may be changed according to the observed position.

In this specification, terms such as include or have means that the features or components described in the specification are present, and the possibility that one or more other features or components may be added is not excluded in advance.

The terms first, second, etc. used herein may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

In interpreting the components, it is interpreted as including an error range even if there is no separate explicit description.

In the present specification, in "a to b" representing a numerical range, "to" is defined as ≥a and ≤b.

A solar cell according to one aspect includes a substrate, an aluminum oxide layer formed on at least one surface of the substrate, and an electrode connected to the substrate through the aluminum oxide layer, the electrode comprising a conductive powder and a predetermined glass frit can do.

The substrate has a first conductivity type region (eg, n-layer or p-layer) and a second conductivity-type region (eg, p-layer or n-layer) as an emitter forming a pn junction with the first conductivity-type region (eg, p-layer or n-layer). may include. The first conductivity type region may be formed by doping the first conductivity type impurity, and the second conductivity type region may be formed by doping the second conductivity type impurity. The thickness of the substrate may be, for example, 100 to 300 μm, but is not limited thereto.

An aluminum oxide layer may be formed as a passivation layer on at least one surface of the substrate. Such an aluminum oxide layer may improve an open circuit voltage and a short circuit current by improving passivation characteristics by fixed charge and hydrogen passivation. The thickness of the aluminum oxide layer may be, for example, 0.5 to 20 nm, but is not limited thereto.

An electrode including a conductive powder and a predetermined glass frit may be formed on the aluminum oxide layer.

The conductive powder may include, for example, one or more metal powders of silver (Ag), gold (Au), platinum (Pt), palladium (Pd), aluminum (Al), and nickel (Ni), but is not limited thereto. it is not According to one embodiment, the conductive powder may include silver powder.

The particle shape of the conductive powder is not particularly limited, and particles of various shapes, for example, particles having a spherical, plate-like or amorphous shape may be used.

The conductive powder may be a powder having a particle size of a nano size or a micro size, for example, a conductive powder having a size of several tens to hundreds of nanometers, or a conductive powder having a size of several to several tens of micrometers. In addition, as the conductive powder, two or more conductive powders having different sizes may be mixed and used.

The average particle diameter (D ₅₀ ) of the conductive powder may be 0.1 to 10 μm, for example, 0.5 to 5 μm. In the above range, the contact resistance and the series resistance may be lowered. The average particle diameter (D ₅₀ ) may be measured using a 1064LD model manufactured by CILAS, after ultrasonically dispersing the conductive powder in isopropyl alcohol (IPA) at 25° C. for 3 minutes.

The glass frit is for generating crystal grains of the conductive powder in the first or second conductive type region by etching the passivation layer and melting the conductive powder during the firing process of the composition for forming a solar cell electrode. In addition, the glass frit improves adhesion between the conductive powder and the wafer and softens during sintering to induce the effect of lowering the sintering temperature.

The glass frit has a total mole % of lead (Pb), tellurium (Te) and lithium (Li) of 50 to 95 mole %, and a mole ratio of calcium (Ca) and silicon (Si) of 1: 0.005 to 10 lead- and a tellurium-lithium-calcium-silicon-oxide (Pb-Te-Li-Ca-Si-O)-based glass frit. Since the aluminum oxide layer is relatively hard, it is difficult to etch the aluminum oxide layer with a conventional glass frit, and as a result, there is a problem in that the contact resistance of the solar cell is increased. However, the above-described Pb-Te-Li-Ca-Si-O-based glass frit contains a predetermined amount of lead, tellurium, lithium, calcium and silicon, so that an appropriate level of Ca-Si-Al ternary reaction during the firing process It is possible to directly etch the aluminum oxide layer by inducing , and as a result, the solar cell can have low contact resistance and excellent conversion efficiency. For example, the total mole % of lead (Pb), tellurium (Te) and lithium (Li) in the Pb-Te-Li-Ca-Si-O-based glass frit is 50 to 95 mol%, for example 60 to 90 mol%, for example, may be 55 to 80 mol%, but is not limited thereto. For example, the molar ratio of calcium (Ca) and silicon (Si) in the Pb-Te-Li-Ca-Si-O-based glass frit is 1: 0.005 to 10, for example 1: 0.05 to 10, another example For example, it may be 1: 0.1 to 8, but is not limited thereto.

According to an exemplary embodiment, the Pb-Te-Li-Ca-Si-O-based glass frit may include lead (Pb) oxide in an amount of 0.1 to 60 mol%. In the above range, the contact resistance may be improved and the conversion efficiency may be excellent. For example, the Pb-Te-Li-Ca-Si-O-based glass frit contains 5 to 50 mol% of lead (Pb) oxide, for example, 10 to 50 mol%, for another example, from 10 to 45 mol%. %, but is not limited thereto.

According to an exemplary embodiment, the Pb-Te-Li-Ca-Si-O-based glass frit may include tellurium (Te) oxide in an amount of 15 to 70 mol%. In the above range, the contact resistance may be improved and the conversion efficiency may be excellent. For example, the Pb-Te-Li-Ca-Si-O-based glass frit contains 15 to 60 mol% of tellurium (Te) oxide, for example 15 to 55 mol%, for another example 15 to 45 mol%. It may be included in mole %, but is not limited thereto.

According to an exemplary embodiment, the Pb-Te-Li-Ca-Si-O-based glass frit may include lithium (Li) oxide in an amount of 0.1 to 35 mol%. In the above range, the contact resistance may be improved and the conversion efficiency may be excellent. For example, the Pb-Te-Li-Ca-Si-O-based glass frit contains 1 to 30 mol% of lithium (Li) oxide, for example 5 to 25 mol%, for another example, 8 to 20 mol% %, but is not limited thereto.

According to one embodiment, the Pb-Te-Li-Ca-Si-O-based glass frit may include calcium (Ca) oxide in an amount of 0.1 to 15 mol%. In the above range, the contact resistance may be improved and the conversion efficiency may be excellent. For example, the Pb-Te-Li-Ca-Si-O-based glass frit contains 0.1 to 10 mol% of calcium (Ca) oxide, for example 0.1 to 8 mol%, for another example, 0.2 to 6 mol% %, but is not limited thereto.

According to one embodiment, the Pb-Te-Li-Ca-Si-O-based glass frit may include 0.1 to 30 mol% of silicon (Si) oxide. In the above range, the contact resistance may be improved and the conversion efficiency may be excellent. For example, the Pb-Te-Li-Ca-Si-O-based glass frit contains 0.1 to 20 mol% of silicon (Si) oxide, for example 0.5 to 15 mol%, for another example, 1 to 10 mol% %, but is not limited thereto.

According to one embodiment, the Pb-Te-Li-Ca-Si-O-based glass frit is bismuth (Bi), zinc (Zn), sodium (Na), phosphorus (P), germanium (Ge), gallium (Ga) , silver (Ag), iron (Fe), tungsten (W), magnesium (Mg), molybdenum (Mo), cesium (Cs), niobium (Nb), strontium (Sr), titanium (Ti), tin (Sn) , indium (In), vanadium (V), barium (Ba), nickel (Ni), copper (Cu), potassium (K), arsenic (As), selenium (Se), cobalt (Co), zirconium (Zr) , manganese (Mn), aluminum (Al), thallium (Tl), tantalum (Ta), cerium (Ce), and may further include one or more of boron (B). For example, a Pb-Te-Li-Ca-Si-O-based glass frit contains greater than 0 to 5 mole % (eg 0.1 to 5 mole %, other such as 0.1 to 3 mole %) aluminum (Al) oxide. %), and in this case, it is possible to prevent the glass frit from excessively etching the aluminum oxide layer, but is not limited thereto.

The shape and size of the glass frit are not particularly limited. For example, the shape of the glass frit may be spherical or irregular, and the average particle diameter (D ₅₀ ) of the glass frit may be 0.1 to 10 μm. The average particle diameter (D ₅₀ ) may be measured using a 1064LD model manufactured by CILAS after ultrasonically dispersing the glass frit in isopropyl alcohol (IPA) at 25° C. for 3 minutes.

Glass frits may be prepared from the elements and/or element oxides described above using conventional methods. For example, after mixing the above-described elements and/or element oxides using a ball mill or a planetary mill, the mixed composition is melted at 800 to 1,300°C, and 25°C After quenching in the , the obtained result can be obtained by pulverizing by a disk mill, a planetary mill, or the like.

The electrode may be formed from a composition for forming a solar cell electrode including a conductive powder, a glass frit, and an organic vehicle. For example, it may be formed by mixing a conductive powder, a glass frit, and an organic vehicle to form a composition for forming a solar cell electrode, coating it on an aluminum oxide layer, and then sintering. Since the conductive powder and the glass frit have been described above, a detailed description thereof will be omitted.

The organic vehicle imparts viscosity and rheological properties suitable for printing to the composition through mechanical mixing with the inorganic component of the composition for forming a solar cell electrode.

As the organic vehicle, an organic vehicle typically used in a composition for forming a solar cell electrode may be used, and may include a binder resin, a solvent, and the like.

As the binder resin, an acrylate-based resin or a cellulose-based resin may be used. For example, ethyl cellulose may be used as the binder resin. In another example, as the binder resin, ethyl hydroxyethyl cellulose, nitrocellulose, a mixture of ethyl cellulose and phenol resin, alkyd resin, phenol-based resin, acrylic acid ester-based resin, xylene-based resin, polybutene-based resin, polyester-based resin , urea-based resin, melamine-based resin, vinyl acetate-based resin, wood rosin, or polymethacrylate of alcohol may be used.

Examples of the solvent include hexane, toluene, ethyl cellosolve, cyclohexanone, butyl cellosolve, butyl carbitol (diethylene glycol monobutyl ether), dibutyl carbitol (diethylene glycol dibutyl ether), butyl carbitol acetate (diethylene glycol monobutyl ether acetate), propylene glycol monomethyl ether, hexylene glycol, terpineol, methyl ethyl ketone, benzyl alcohol, gamma butyrolactone, ethyl lactate or 2,2; 4-trimethyl-1,3-pentanediol monoisobutyrate (eg, Texanol) and the like may be used alone or in combination.

The amount of the conductive powder, glass frit and organic vehicle to be used is not particularly limited. The conductive powder, for example, may be included in an amount of 60 to 95% by weight, for example, 70 to 90% by weight of the total weight of the composition for forming a solar cell electrode, and the conversion efficiency of the solar cell is excellent in the above range and the paste is smoothly formed. may be made, but is not limited thereto. The glass frit, for example, may be included in an amount of 0.1 to 20% by weight, for example, 0.1 to 10% by weight of the total weight of the composition for forming a solar cell electrode, and pn junction stability can be secured under various sheet resistances in the above range, It is possible to minimize the resistance and ultimately improve the efficiency of the solar cell, but is not limited thereto. The organic vehicle may be included, for example, in an amount of 1 to 30% by weight, for example, 3 to 20% by weight of the total weight of the composition for forming a solar cell electrode, and sufficient adhesive strength and excellent printability can be ensured in the above range. However, the present invention is not limited thereto.

In addition to the above components, the composition for forming a solar cell electrode contains a dispersant, a thixotropic agent, a plasticizer, a viscosity stabilizer, an antifoaming agent, a pigment, a UV stabilizer, an antioxidant, a coupling agent, etc. as necessary to improve flow characteristics, process characteristics and stability. It may further include alone or two or more types. These may be included in an amount of 0.1 to 5% by weight based on the total weight of the composition for forming a solar cell electrode, but the content may be changed as needed.

The above-described solar cell may include, but is not limited to, a solar cell having a passivated emitter solar cell (PEC), a passivated emitter and rear cell (PERC), or a passivated emitter real locally diffused (PERL) structure.

1 schematically shows a solar cell according to an embodiment of the present invention.

Referring to FIG. 1 , the solar cell 100 includes a first conductivity type region 112 that is a p-layer (or n-layer) and a second conductivity-type region 111 that is an n-layer (or p-layer) as an emitter. A substrate 110 may be provided.

The upper surface of the substrate 110 is the front portion of the solar cell 100 . The upper surface of the substrate 110 includes an aluminum oxide layer 130 , and a second conductive region 111 passing through the aluminum oxide layer 130 . The front electrode 121 connected to ) is formed. The front electrode 121 may include the conductive powder and the Pb-Te-Li-Ca-Si-O-based glass frit described above.

A lower surface of the substrate 110 is a rear surface of the solar cell 100 , and a rear electrode 122 is formed on the lower surface of the substrate 110 .

According to one embodiment, between the second conductive region 111 and the aluminum oxide layer 130, on the upper surface of the aluminum oxide layer 130, or on both, a passivation layer (not shown) except for the aluminum oxide layer, For example, a silicon oxide layer, a silicon nitride layer and/or a silicon nitride oxide layer may be additionally formed, and the stacking order thereof is not particularly limited. For example, the silicon oxide layer/silicon nitride layer/aluminum oxide layer 130 may be sequentially stacked on the upper surface of the second conductive region 111 , but the present invention is not limited thereto.

According to one embodiment, the aluminum oxide layer 130 may have a texturing structure. According to another embodiment, when it further includes a silicon oxide layer, a silicon nitride layer and/or a silicon nitride oxide layer, an aluminum oxide layer 130, and one of a silicon oxide layer, a silicon nitride layer and/or a silicon nitride oxide layer. The species or more may have a texturing structure.

2 schematically shows a solar cell according to another embodiment of the present invention.

Referring to FIG. 2 , the solar cell 200 includes a first conductivity type region 212 that is a p-layer (or n-layer) and a second conductivity-type region 211 that is an n-layer (or p-layer) as an emitter. A substrate 210 is provided, a front electrode 221 is formed on an upper surface of the substrate 210 , and a lower surface of the substrate 210 passes through an aluminum oxide layer 230 and an aluminum oxide layer 230 . Thus, a rear electrode 222 connected to the first conductive region 212 is formed. The rear electrode 222 may include conductive powder and the above-described Pb-Te-Li-Ca-Si-O-based glass frit.

According to one embodiment, between the first conductive region 212 and the aluminum oxide layer 230, on the lower surface of the aluminum oxide layer 230, or on both, a passivation layer (not shown) except for the aluminum oxide layer; For example, a silicon oxide layer, a silicon nitride layer, and/or a silicon nitride oxide layer may be additionally formed, and the stacking order thereof is not particularly limited, and they may optionally have a texturing structure.

3 schematically shows a solar cell according to another embodiment of the present invention.

Referring to FIG. 3 , the solar cell 300 includes a first conductivity type region 312 that is a p-layer (or n-layer) and a second conductivity-type region 311 that is an n-layer (or p-layer) as an emitter. A substrate 310 is provided, and the upper surface of the substrate 310 includes an aluminum oxide layer 330 , and a front electrode 321 passing through the aluminum oxide layer 330 and connected to the second conductive region 311 . The lower surface of the substrate 310 includes an aluminum oxide layer 330 , and a rear electrode 322 penetrating through the aluminum oxide layer 330 and connected to the first conductive region 312 . Each of the front electrode 321 and the rear electrode 322 may include the conductive powder and the Pb-Te-Li-Ca-Si-O-based glass frit described above.

According to one embodiment, between the second conductive region 311 and the aluminum oxide layer 330 , on the upper surface of the aluminum oxide layer 330 , and between the first conductive region 312 and the aluminum oxide layer 330 . In and/or on the lower surface of the aluminum oxide layer 330, a passivation layer (not shown) excluding the aluminum oxide layer, for example, a silicon oxide layer, a silicon nitride layer and/or a silicon nitride oxide layer may be additionally formed. and their stacking order is not particularly limited, and they may optionally have a texturing structure.

The above-described solar cell may be manufactured by printing and firing a composition for forming a solar cell electrode on a substrate having an aluminum oxide layer formed on at least one surface to form a rear electrode and a front electrode. For example, after the composition for forming a solar cell electrode is printed and applied to the rear surface of the wafer, it is dried at 200 to 400° C. for 10 to 60 seconds to perform a pre-preparation step for the rear electrode. In addition, the composition for forming a solar cell electrode may be printed on the front surface of the wafer and dried to perform a pre-preparation step for the front electrode. Thereafter, a firing process of firing at 400 to 950° C. for 30 to 210 seconds may be performed to form the front electrode and the rear electrode.

Hereinafter, a solar cell according to an embodiment of the present invention will be described in more detail by way of example. However, this is presented as a preferred example of the present invention, and it cannot be construed as limiting the present invention in any sense.

Example

Example 1

After sufficiently dissolving 2 parts by weight of ethyl cellulose (STD4, Dow chemical) as a binder resin at 60° C. with 6.5 parts by weight of terpinol (Nippon Terpine) as a solvent, spherical silver powder (4-8F, Dowa) having an average particle diameter of 2.0 μm Company) 90 parts by weight, 1.5 parts by weight of the glass frit A of Table 1 below having an average particle diameter of 1.0 μm, mixed evenly, and mixed and dispersed with a 3-roll kneader to prepare a composition for forming a solar cell electrode.

After texturing on the entire surface of the wafer (boron-doped p-type wafer) _{, an n+ layer is formed with POCl 3} , and aluminum paste is printed on the back side of the monocrystalline wafer on which an aluminum oxide layer is formed. dried for 30 seconds. Thereafter, the prepared composition for forming a solar cell electrode was screen-printed on the entire surface of the wafer and dried at 300° C. for 30 seconds. The cell formed by the above process was fired at 940° C. for 70 seconds using a belt-type firing furnace to prepare a solar cell.

Examples 2 to 5 and Comparative Examples 1 to 3

A solar cell was manufactured in the same manner as in Example 1, except that glass frits B to H of Table 1 were used instead of glass frit A.

glass frit PbO
(mole%) TeO ₂
(mole%) Li ₂ O
(mole%) CaO
(mole%) SiO ₂
(mole%) Al ₂ O ₃
(mole%) Ca: Si
(molar ratio) Pb + Te + Li
(mole%) Example 1 A 26.27 52.30 13.83 5.78 1.82 - 1: 0.31 92.40 Example 2 B 24.30 47.24 17.55 4.16 6.75 - 1:1.62 89.09 Example 3 C 17.23 37.31 21.34 4.95 19.17 - 1: 3.87 75.88 Example 4 D 28.74 42.34 15.62 1.61 11.69 - 1: 7.27 86.70 Example 5 E 25.82 51.42 13.60 5.69 1.79 1.68 1: 0.31 90.84 Comparative Example 1 F 23.67 34.87 16.48 1.32 23.66 - 1:17.87 75.02 Comparative Example 2 G 22.08 39.96 8.41 29.44 0.11 - 1: 0.003 70.45 Comparative Example 3 H 23.33 58.00 14.78 2.92 0.97 - 1: 0.33 96.11

Evaluation Example: Electrical Characteristics

Short-circuit current (Isc, unit: A), open-circuit voltage (Voc, unit: mV), series resistance using solar cell efficiency measuring equipment (Halm, Fortix tech) for the solar cells prepared in Examples and Comparative Examples (Rs, unit: Ω), conversion efficiency (Eff, unit: %), and Fill Factor (FF, unit: %) were measured, and the results are shown in Table 2 below.

glass frit isc Voc Rs FF Eff Example 1 A 9.486 643.68 0.001832 80.79 20.65 Example 2 B 9.498 644.25 0.002038 80.50 20.62 Example 3 C 9.501 643.94 0.002022 80.51 20.62 Example 4 D 9.494 644.89 0.00212 80.48 20.63 Example 5 E 9.460 644.74 0.001941 80.66 20.59 Comparative Example 1 F 9.469 643.52 0.002191 80.18 20.45 Comparative Example 2 G 9.468 644.67 0.002346 80.00 20.44 Comparative Example 3 H 9.430 645.31 0.002141 80.38 20.47

As can be seen from Table 2 above, the solar cells of Examples 1 to 5 having the electrode including the glass frit of the present invention on the aluminum oxide layer have lower contact resistance and conversion compared to Comparative Examples 1 to 3, which is not. It can be seen that the efficiency is excellent.

Up to now, the present invention has been looked at mainly with respect to the embodiments. Those of ordinary skill in the art to which the present invention pertains will understand that the present invention can be implemented in modified forms without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments are to be considered in an illustrative rather than a restrictive sense. The scope of the present invention is indicated in the claims rather than the foregoing description, and all differences within the scope equivalent thereto should be construed as being included in the present invention.

100, 200, 300: solar cell
110, 210, 310: substrate
111, 211, 311: second conductive type region
112, 212, 312: first conductive type region
120, 220, 320: electrode
121, 221, 321: front electrode
122, 222, 322: back electrode
130, 230, 330: aluminum oxide layer

Claims (10)

a substrate including a first conductivity type region and a second conductivity type region forming a pn junction with the first conductivity type region;
an aluminum oxide layer formed on at least one surface of the substrate; and
an electrode connected to the first conductive region or the second conductive region through the aluminum oxide layer; A solar cell comprising
The electrode comprises a conductive powder and a glass frit,
In the glass frit, the total mole % of lead (Pb), tellurium (Te) and lithium (Li) is 50 to 95 mole %, and the mole ratio of calcium (Ca) and silicon (Si) is 1: 0.005 to 10 lead. - A solar cell comprising a glass frit based on tellurium-lithium-calcium-silicon-oxide (Pb-Te-Li-Ca-Si-O).
According to claim 1,
The Pb-Te-Li-Ca-Si-O-based glass frit comprises lead (Pb) oxide in an amount of 0.1 to 60 mol%, a solar cell.
According to claim 1,
The Pb-Te-Li-Ca-Si-O-based glass frit comprises 15 to 70 mol% of tellurium (Te) oxide.
According to claim 1,
The Pb-Te-Li-Ca-Si-O-based glass frit comprises lithium (Li) oxide in an amount of 0.1 to 35 mol%, a solar cell.
According to claim 1,
The Pb-Te-Li-Ca-Si-O-based glass frit contains calcium (Ca) oxide in an amount of 0.1 to 15 mol%, a solar cell.
According to claim 1,
The Pb-Te-Li-Ca-Si-O-based glass frit comprises a silicon (Si) oxide in an amount of 0.1 to 30 mol%, a solar cell.
According to claim 1,
The Pb-Te-Li-Ca-Si-O-based glass frit is bismuth (Bi), zinc (Zn), sodium (Na), phosphorus (P), germanium (Ge), gallium (Ga), silver (Ag) , iron (Fe), tungsten (W), magnesium (Mg), molybdenum (Mo), cesium (Cs), niobium (Nb), strontium (Sr), titanium (Ti), tin (Sn), indium (In) , vanadium (V), barium (Ba), nickel (Ni), copper (Cu), potassium (K), arsenic (As), selenium (Se), cobalt (Co), zirconium (Zr), manganese (Mn) , A solar cell further comprising at least one of aluminum (Al), thallium (Tl), tantalum (Ta), cerium (Ce), and boron (B).
According to claim 1,
The Pb-Te-Li-Ca-Si-O-based glass frit further comprises more than 0 to 5 mol% of aluminum (Al) oxide.
According to claim 1,
The electrode is prepared from a composition for forming a solar cell electrode comprising a conductive powder, a glass frit and an organic vehicle.
10. The method of claim 9,
The composition is
60 to 95 wt% of the conductive powder;
0.1 to 20% by weight of the glass frit; and
1 to 30% by weight of the organic vehicle; A solar cell comprising

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