KR20110093046A - Silicon thin film solar cell and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A thin silicon film solar battery and a manufacturing method thereof are provided to adjust the amount of oxygen atoms included in the intrinsic semiconductor layer of a second photoelectric converting unit, thereby balancing the amount of currents in each photoelectric conversion unit. CONSTITUTION: A photoelectric conversion unit includes a first photoelectric conversion unit(130), a second photoelectric conversion unit(140), and a third photoelectric conversion unit. The second photoelectric conversion unit includes a p-type doping layer(141), an intrinsic semiconductor layer(142), and an n-doped layer(143). The p-type doping layer and the n-doped layer are made of one of hydrogenated microcrystalline silicon or hydrogenated microcrystalline silicon oxide. The intrinsic semiconductor layer is made of hydrogenated microcrystalline silicon oxide.

Description

Silicon thin film solar cell and its manufacturing method {SILICON THIN FILM SOLAR CELL AND MANUFACTURING METHOD THEREOF}

The present invention relates to a silicon thin film solar cell, and more particularly, to a multi-junction silicon thin film solar cell having a junction of triple junction or more, and a manufacturing method thereof.

Solar cells use the sun, which is an almost unlimited energy source, as an energy source, generate little pollutants in the power generation process, have a long life span of more than 20 years, and have a high ripple effect in related industries. It is attracting much attention, and as a result, many countries are fostering solar cells as the next generation major industries.

Currently, more than 90% of solar cells are manufactured and sold based on single crystal or polycrystalline silicon wafers (Si wafer), and thin-film silicon-based solar cells are manufactured and sold on a small scale.

The biggest problem of solar cells is that the cost of power generation is very high compared to other energy sources. Therefore, in order to meet the demand for clean energy in the future, the cost of power generation must be drastically reduced.

However, at present, so-called bulk silicon solar cells based on monocrystalline or polycrystalline silicon wafers require at least 150 µm in thickness, so a large part of the cost is accounted for by material costs, that is, silicon raw materials. The possibility of lowering costs is not easy because it cannot keep up with the rapidly increasing demand.

On the contrary, since the thin film type solar cell has a thickness of 2 μm or less, the amount of raw materials used is very small compared to the bulk type solar cell, thereby significantly reducing the material cost. Therefore, it has a great advantage compared to bulk solar cells in terms of power generation cost. However, thin-film solar cells have about half the power generation performance as compared to bulk solar cells.

In general, when expressing the efficiency of solar cells, the amount of power that can be obtained at 100 ㎽ / ㎠ light amount is expressed in%. The efficiency of bulk solar cells is 12% to 20%, but the efficiency of thin film solar cells is 8% to 9 About%. Therefore, the efficiency of thin film solar cells is lower than that of bulk solar cells.

The most basic model of a thin film solar cell has a single junction type structure. Herein, the single junction thin film solar cell includes an intrinsic layer for absorbing light, a p-type doped layer disposed on the upper and lower portions of the intrinsic semiconductor layer to form an internal electric field for photo-generated charge separation, and The photoelectric conversion unit including the n-type doped layer refers to a solar cell formed on a substrate.

However, the single junction thin film solar cell has a low efficiency. Therefore, in order to increase efficiency, a double junction (tandem or double junction) type in which two photoelectric conversion parts are stacked and a triple junction type thin film solar cell in which three photoelectric conversion parts are stacked are being developed.

The double-junction and triple-junction thin-film solar cells are formed of various kinds of materials having different band gaps (Eg) to form intrinsic semiconductor layers for light absorption of different photoelectric conversion portions, thereby extending the light absorption spectrum band. It is configured to improve the efficiency by increasing the open voltage (Voc).

Among the triple-junction thin film solar cells, the intrinsic semiconductor layer of the first photoelectric conversion portion in which sunlight is absorbed first is a semiconductor material having a high optical bandgap (eg, amorphous silicon (a-)). Si)), and the intrinsic semiconductor layer of the second photoelectric conversion portion positioned on the first photoelectric conversion portion may be a semiconductor material having a low optical band gap (for example, amorphous silicon germanium (a-SiGe) or microcrystalline silicon (μc). (Si)), and the intrinsic semiconductor layer of the third photoelectric conversion unit positioned on the second photoelectric conversion unit is amorphous silicon germanium or finer having a higher germanium (Ge) content than the material forming the intrinsic semiconductor layer of the second photoelectric conversion unit. It is known to form crystalline silicon germanium (μc-Si (Ge)).

In the triple junction type thin film solar cell having such a configuration, among the components of the solar light incident through the substrate, mainly light having a short wavelength is absorbed by the intrinsic semiconductor layer of the first photoelectric conversion part, and sunlight having a wavelength that is not absorbed by the first photoelectric conversion part. The component is absorbed in the intrinsic semiconductor layer of the second photoelectric converter and the third photoelectric converter.

However, each of the intrinsic semiconductor layers of the first to third photoelectric conversion portions is a triple junction solar cell made of a-Si / a-SiGe / μc-Si and a-Si / μc-Si / μc-Si. Comparing the quantum efficiency (QE: quantum efficiency) of the triple junction solar cell made up, the current of the second photovoltaic conversion part of the intrinsic semiconductor layer made of a-SiGe is made of the first semiconductor layer made of μc-Si. Since there is a limit to increase the efficiency because the element type is often limited to the current of the 3 photoelectric conversion section to limit the second photoelectric conversion section, the latter solar cell has a second photoelectric conversion section and a third photoelectric conversion section. Since the negative intrinsic semiconductor layers are all made of μc-Si, sufficient current can be produced in the second photoelectric conversion unit, so the latter solar cell has an element structure that is advantageous in improving efficiency in terms of current.

However, in terms of open voltage (Voc), the former solar cell has a total open voltage of 1.0 V in the first photoelectric converter, 0.75 V in the second photoelectric converter, and 0.5 V in the third photoelectric converter. An open voltage of 2.25V can be obtained. However, in the latter solar cell, since the open voltage of the first and third photoelectric converters is the same as the former solar cell, the open voltage of the second photoelectric converter is 0.5V and the total open voltage is 2.0V. The solar cell has an advantageous device structure.

That is, since the former solar cell has a device structure that is difficult to further increase efficiency in terms of current and the latter solar cell, it is easy for both the former and the latter solar cells to achieve efficiency of 13.5% or more. Not.

The technical problem to be achieved by the present invention is to provide a silicon thin film solar cell with improved efficiency made of a multi-junction of triple junction or more.

Another object of the present invention is to provide a method of manufacturing a multi-junction silicon thin film solar cell.

Silicon thin film solar cell according to an embodiment of the present invention, the substrate to which sunlight is incident; And a first electrode, at least three photoelectric conversion parts, and a second electrode positioned on the substrate, wherein the at least three photoelectric conversion parts are sequentially positioned on the first electrode; A photoelectric conversion unit and a third photoelectric conversion unit, wherein the second photoelectric conversion unit includes a p-type doping layer, an intrinsic semiconductor layer, and an n-type doping layer, and the p-type doping layer and the n-type doping layer are hydrogenated fine crystals. It is composed of any one selected from silicon (μc-Si: H) or hydrogenated microcrystalline silicon oxide (μc-SiOx: H), and the intrinsic semiconductor layer is hydrogenated microcrystalline silicon oxide (μc-SiOx: H). Is made of.

The oxygen content in the intrinsic semiconductor layer of the second photoelectric converter is 1% to 15%, and the crystallinity of the intrinsic semiconductor layer of the second photoelectric converter is 15% to 50%.

The intrinsic semiconductor layer of the first photoelectric conversion unit may be made of hydrogenated amorphous silicon (a-Si: H), and the intrinsic semiconductor layer of the third photoelectric conversion unit may be hydrogenated microcrystalline silicon (μc-Si: H) or hydrogenated fine particles. It may be made of crystalline silicon germanium (μc-SiGe: H). At least one intermediate reflective layer may be positioned between the first to third photoelectric conversion units.

A silicon thin film solar cell having such a configuration may include forming a first photoelectric conversion unit on a surface of a substrate on which a first electrode is formed; Forming a second photoelectric converter on the first photoelectric converter; And forming a third photoelectric converter on the second photoelectric converter, wherein forming the second photoelectric converter includes hydrogenated microcrystalline silicon (μc-Si: H) or hydrogenated microcrystalline silicon oxide (μc). Forming a p-type doped layer with any one of -SiOx: H); Forming an intrinsic semiconductor layer from hydrogenated microcrystalline silicon oxide (μc-SiOx: H); And forming an n-type doped layer with any one material selected from hydrogenated microcrystalline silicon (μc-Si: H) or hydrogenated microcrystalline silicon oxide (μc-SiOx: H). It can manufacture by a method.

The forming of the first photoelectric conversion unit may include forming an intrinsic semiconductor layer on the first electrode with hydrogenated amorphous silicon (a-Si: H), and the forming of the third photoelectric conversion unit may include hydrogenated fine particles. Forming an intrinsic semiconductor layer over the second photoelectric conversion portion with crystalline silicon (μc-Si: H) or forming an intrinsic semiconductor layer over the second photoelectric conversion portion with hydrogenated fine crystalline silicon germanium (μc-SiGe: H) It may include.

According to this feature, the hydrogenated microcrystalline silicon oxide forming the intrinsic semiconductor layer of the second photoelectric conversion portion has a lower bandgap than amorphous silicon germanium in terms of short-circuit current density, thereby increasing short-circuit current density and hydrogenating in terms of open voltage. Since the microcrystalline silicon oxide has a higher band gap than the microcrystalline silicon, the open voltage can be increased. Therefore, the efficiency of a silicon thin film solar cell can be improved.

In addition, when the content of oxygen atoms contained in the intrinsic semiconductor layer of the second photoelectric conversion unit is adjusted to a suitable band gap made of microcrystalline silicon oxide doped with both the intermediate reflective layer and the rear reflective layer, the thickness of each reflective layer is optimized to optimize each photoelectric conversion. A high efficiency solar cell can be realized by balancing the current flowing through the negative.

1 is a partial cross-sectional view of a triple junction type silicon thin film solar cell according to a first embodiment of the present invention.
2 is a table showing efficiency and characteristic values of the triple junction type silicon thin film solar cell according to the first embodiment of the present invention.
3 is a partial cross-sectional view of a triple junction type silicon thin film solar cell according to a second embodiment of the present invention.
4 is a partial cross-sectional view of a triple junction type silicon thin film solar cell according to a third embodiment of the present invention.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted for simplicity of explanation, and like reference numerals designate like parts throughout the specification.

In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. When a layer, film, region, plate, or the like is referred to as being "on" another portion, it includes not only the case directly above another portion but also the case where there is another portion in between. On the contrary, when a part is "just above" another part, there is no other part in the middle.

An embodiment of the present invention will now be described with reference to the accompanying drawings.

1 is a schematic view of a silicon thin film solar cell according to a first embodiment of the present invention, and is a partial cross-sectional view of a triple junction solar cell. However, the present invention described below is applicable to a silicon thin film solar cell having four or more photoelectric conversion units.

Referring to FIG. 1, the triple junction type silicon thin film solar cell according to the present exemplary embodiment has a superstrate-type structure in which light is incident through the substrate 110.

In more detail, the triple junction type silicon thin film solar cell includes a substrate 110 made of glass or transparent plastic, a transparent conductive oxide (TCO) 120 positioned on the substrate 110, and a transparent electrode ( The first photoelectric converter 130 positioned on the 120, the second photoelectric converter 140 positioned on the first photoelectric converter 130, and the third photoelectric converter 140 positioned on the second photoelectric converter 140. 150 and a rear electrode 170 positioned on the third photoelectric converter 150. In this case, the transparent electrode 120 is a first electrode and the rear electrode 170 is a second electrode.

The conductive transparent electrode 120 is formed on the entire surface of the substrate 110 and is electrically connected to the first photoelectric converter 130. Therefore, the conductive transparent electrode 120 collects and outputs one of the carriers generated by light, for example, holes. The conductive transparent electrode 120 may also function as an antireflection film.

The upper surface of the conductive transparent electrode 120 is formed of a texturing surface having a plurality of irregularities (not shown) having a random pyramid structure. As such, when the surface of the conductive transparent electrode 120 is formed as a texturing surface, the light reflectivity of the conductive transparent electrode is reduced to increase light absorption, thereby improving efficiency of the solar cell. At this time, the height of the irregularities formed may be about 1 ㎛ to 10 ㎛.

The conductive transparent electrode 120 requires a high light transmittance and a high electrical conductivity so that most of the light passes and the electricity can flow well. The conductive transparent electrode 120 may be formed of indium tin oxide (ITO), tin oxide (SnO _2, etc.), AgO, ZnO- (Ga ₂ O ₃ or Al ₂ O ₃ ), and fluorine tin oxide (fluorine tin oxide). tin oxide: FTO) and mixtures thereof. The resistivity range of the conductive transparent electrode 120 may be about 10 ⁻² Ω-cm to 10 ⁻¹¹ Ω-cm.

The first photoelectric converter 130 may be formed of an amorphous silicon cell using hydrogenated amorphous silicon (a-Si: H), and has an optical band gap of about 1.7 eV, and may include near ultraviolet light, violet light, blue light, and the like. It mainly absorbs light of the same short wavelength band.

The first photoelectric conversion unit 130 is a first p-type doped layer 131, a first intrinsic semiconductor layer 132, and a first conductive semiconductor layer sequentially stacked on the conductive transparent electrode 120. And a first n-type doped layer 133, which is a semiconductor layer of a second conductivity type opposite to the first conductivity type.

The first p-type doped layer 131 may be formed by mixing a source gas including silicon (Si) and a gas containing impurities of trivalent elements such as boron, gallium, and indium. In the present exemplary embodiment, the first p-type doped layer 131 is formed of hydrogenated amorphous silicon (a-Si: H), but may be formed of a material other than hydrogenated amorphous silicon.

The first intrinsic semiconductor layer 132 is to reduce the recombination rate of the carrier and absorb light, and carriers such as electrons and holes are mainly generated therein. The first intrinsic semiconductor layer 132 may be formed of hydrogenated amorphous silicon (a-Si: H), and may have a thickness of about 200 nm to 300 nm.

The first n-type doped layer 133 may be formed by mixing a source gas containing silicon with a gas containing impurities of pentavalent elements such as phosphorus (P), arsenic (As), and antimony (Sb). In the present exemplary embodiment, the first p-type doped layer 131 is formed of hydrogenated amorphous silicon (a-Si: H) similarly to the first n-type doped layer 133, but is formed of a material other than hydrogenated amorphous silicon. It is also possible.

The first photoelectric converter 130 may be formed by chemical vapor deposition (CVD), such as plasma enhanced chemical vapor deposition (PECVD).

Doping layers such as the first p-type doping layer 131 and the first n-type doping layer 133 of the first photoelectric conversion unit 130 form a pn junction with the first intrinsic semiconductor layer 132 interposed therebetween. As a result, electrons and holes generated in the first intrinsic semiconductor layer 132 are separated by the contact potential difference and moved in different directions due to the photovoltatic effect. For example, holes move toward the conductive transparent electrode 120 through the first p-type doping layer 131, and electrons move toward the rear electrode 170 through the first n-type doping layer 133.

The second photoelectric converter 140 positioned on the first photoelectric converter 130 is a second p-type doped layer sequentially formed on the first n-type doped layer 133 similarly to the first photoelectric converter 130. 141, a second intrinsic semiconductor layer 142, and a second n-type doped layer 143, which are the same as the first photoelectric converter 130, such as CVD, such as PECVD. It can be formed as.

The second photoelectric converter 140 is to improve the light efficiency of the silicon thin film solar cell by controlling the open voltage and the short-circuit current density. In the present embodiment, the second p-type doped layer 141 and the second intrinsic semiconductor layer are used. Both the 142 and the second n-type doped layer 143 are formed of hydrogenated fine crystal silicon oxide (μc-SiOx: H). However, the second p-type doped layer 141 and the second n-type doped layer 143 may be formed of hydrogenated microcrystalline silicon (μc-Si: H).

The second intrinsic semiconductor layer 142 mainly absorbs light having a long wavelength band applied thereto to generate electrons and holes. In the present embodiment, the second intrinsic semiconductor layer 142 may have a thickness of about 1500 nm to 2000 nm.

Similar to the first photoelectric converter 130, the second p-type and n-type doped layers 141 and 143 of the second photoelectric converter 140 may have a pn junction with the second intrinsic semiconductor layer 142 interposed therebetween. The resulting holes are collected by moving toward the conductive transparent electrode 120 through the second p-type doped layer 141, and the generated electrons are collected through the second n-type doped layer 143. Go to 170 and collect.

At this time, the oxygen content and crystallinity in the second intrinsic semiconductor layer 142 play an important role in controlling the open voltage Voc and the short circuit current density Jsc.

Thus, as a result of the experiments of the present inventors, it was found that the oxygen content in the second intrinsic semiconductor layer 142 is 1% to 15%, which is why when the oxygen content is less than 1%, a band gap increase effect can be obtained. This is because when the oxygen content exceeds 15%, the quality of the thin film is degraded due to an increase in defects and an excessive increase in the band gap.

Also, in the case of crystallinity, it is appropriate to be within a range of 15% to 50% when measuring the crystallinity of the second intrinsic semiconductor layer 142 using Raman spectroscopy.

The third photoelectric converter 150 positioned on the second photoelectric converter 140 may be a microcrystal using hydrogenated microcrystalline silicon (μc-Si: H) or hydrogenated microcrystalline silicon germanium (μc-SiGe: H). As a silicon cell, it mainly absorbs light in the long wavelength band from red to near infrared.

The third photoelectric converter 150 may include a third p-type doped layer 151, a third intrinsic semiconductor layer 152, which are sequentially formed on the first n-type doped layer 143 of the second photoelectric converter 140. And a third n-type doped layer 153, and these layers 151 to 153 may be formed by CVD such as PECVD in the same manner as the first and second photoelectric converters 130 and 140.

In the present embodiment, the third p-type doping layer 151, the third intrinsic semiconductor layer 152, and the third n-type doping layer 153 may be hydrogenated microcrystalline silicon (μc-Si: H) or hydrogenated fine particles. It is formed of crystalline silicon germanium (μc-SiGe: H). However, the third p-type doping layer 151 and the third n-type doping layer 153 may have other than hydrogenated microcrystalline silicon (μc-Si: H) and hydrogenated microcrystalline silicon germanium (μc-SiGe: H). It may also be formed of a material.

The back electrode 170 is positioned on the entire surface of the third photoelectric converter 150 and is electrically connected to the third n-type doping layer 153 of the third photoelectric converter 150. The rear electrode 170 collects and outputs electrons among carriers generated through the p-n junction.

Meanwhile, in order to increase light absorption, the first photoelectric converter 130, the second photoelectric converter 140, and the third photoelectric converter 150 may also be formed to have a textured surface.

Figure 2 shows the efficiency and characteristics of the triple junction type silicon thin film solar cell according to an embodiment of the present invention.

In Fig. 2, Voc refers to the open voltage, Jsc refers to the short-circuit current density, FF refers to the fill factor, and Eff refers to the efficiency.

As shown in FIG. 2, intrinsic semiconductor layers of the first photoelectric conversion unit, the second photoelectric conversion unit, and the third photoelectric conversion unit are each hydrogenated amorphous silicon (a-Si: H) / hydrogenated microcrystalline silicon oxide (μc). The solar cell of Example 1 formed of -SiOx: H) / hydrogenated microcrystalline silicon (μc-Si: H) has a charge factor (FF) of the conventional Example 1 (a-Si: H / a-SiGe: H / μc -Si: H) and conventional example 2 (a-Si: H / μc-Si: H / μc-Si: H). However, the open voltage Voc is lower than that of Conventional Example 1 but higher than that of Conventional Example 2, and the short-circuit current density Jsc is the same as that of Conventional Example 2 but higher than that of Conventional Example 1.

Therefore, the silicon thin film solar cell of Example 1 has the same short-circuit current density as that of Conventional Example 2, but the open circuit voltage is increased to improve the efficiency by about 1% compared to the Conventional Examples 1 and 2.

In addition, intrinsic semiconductor layers of the first photoelectric conversion unit, the second photoelectric conversion unit, and the third photoelectric conversion unit are each hydrogenated amorphous silicon (a-Si: H) / hydrogenated microcrystalline silicon oxide (μc-SiOx: H) / The solar cell of Example 2 formed of hydrogenated microcrystalline silicon germanium (μc-SiGe: H) has a charge factor (FF) of the conventional Example 1 (a-Si: H / a-SiGe: H / μc-Si: H). And Example 2 (a-Si: H / μc-Si: H / μc-Si: H) and Example 1, and the open voltage (Voc) is the same as Example 1, the short-circuit current density (Jsc) Is higher than in Example 1.

Therefore, the silicon thin film solar cell of Example 2 has an increased short-circuit current density compared to Example 1, so that the efficiency is further improved by about 1% for Example 1 and Example 2 and about 1.5% for Example 1.

3 is a partial cross-sectional view of a triple junction type silicon thin film solar cell according to a second exemplary embodiment of the present invention, wherein the intermediate reflective layer 180 is disposed between the second photoelectric converter 140 and the third photoelectric converter 150. ) Has the same configuration as that of the embodiment of FIG. 1 described above.

The intermediate reflective layer 180 reflects the short wavelength solar component toward the second photoelectric converter 140, while the long wavelength solar component passes toward the third photoelectric converter 150. The intermediate reflective layer 180 having such a function may be formed of aluminum oxide zinc oxide (ZnO: Al).

3 illustrates that the intermediate reflective layer 180 is formed between the second photoelectric converter 140 and the third photoelectric converter 150, but the intermediate reflective layer 180 is formed of the first photoelectric converter 130 and the first photoelectric converter 130. 2 between the photoelectric converter 140 or between the first photoelectric converter 130 and the second photoelectric converter 140 and between the second photoelectric converter 140 and the third photoelectric converter 150. It can either be located or both.

4 is a partial cross-sectional view of a silicon thin film solar cell according to a third exemplary embodiment of the present invention, wherein a back reflector 160 is positioned between the third photoelectric converter 150 and the back electrode 170. Except for that, it has the same configuration as the above-described embodiment of FIG.

The rear reflective layer 160 reflects the light passing through the third photoelectric converter 150 toward the third photoelectric converter 150 to improve the operation efficiency of the third photoelectric converter 150. It may be formed of the same material as the reflective layer 180.

Although not specifically illustrated, the rear reflective layer 160 may be used together with the intermediate reflective layer 180.

Hereinafter, a method of manufacturing a silicon thin film solar cell according to an embodiment of the present invention.

In the manufacturing method described below, amorphous silicon (a-Si: H) in which the intrinsic semiconductor layers of the first photoelectric conversion unit 130, the second photoelectric conversion unit 140, and the third photoelectric conversion unit 150 are each hydrogenated. / Embodiment 1 formed of hydrogenated microcrystalline silicon oxide (μc-SiOx: H) / hydrogenated microcrystalline silicon (μc-Si: H), but the intrinsic semiconductor layer of the third photoelectric conversion section 150 The solar cell of Example 2, which is formed of hydrogenated microcrystalline silicon germanium (μc-SiGe: H), can also be prepared by a method similar to the method of manufacturing the solar cell of Example 1.

First, the conductive transparent electrode 120 is formed on a substrate 110 made of a transparent material such as glass or plastic. The conductive transparent electrode 20 may be formed by applying a conductive transparent electrode forming paste on the substrate 110 and then performing heat treatment, or may be formed through a deposition method or a plating method using a sputtering process or the like.

The conductive transparent electrode 120 may be formed of indium tin oxide (ITO), tin oxide (SnO _2, etc.), AgO, ZnO- (Ga ₂ O ₃ or Al ₂ O ₃ ), fluorine tin oxide (fluorine tin) oxide: FTO) and mixtures thereof.

Next, the surface of the conductive transparent electrode 120 is textured to form a plurality of irregularities (not shown) in the conductive transparent electrode 120.

Texturing may consist of immersing the semiconductor substrate 100 for a period of time, for example 15 seconds, in a bath containing, for example, a surface etching solution such as about 0.5% hydrogen chloride (HCl). According to the above process, the surface of the conductive transparent electrode 120 in contact with the etching solution is etched to form irregularities having a random pyramid structure or the like.

In this case, the unevenness is generated by a difference in etching speed according to the crystal direction of the transparent electrode 120. The height of the irregularities to be formed, that is, the height of each pyramid structure varies depending on the concentration of the etching solution, the etching time, and the like, and may be about 1 μm to 10 μm.

Next, the first photoelectric conversion unit 130 is formed by sequentially forming the first p-type doped layer 131, the first intrinsic semiconductor layer 132, and the first n-type doped layer 133 by using CVD such as PECVD. Form.

In this case, the first p-type doping layer 131, the first intrinsic semiconductor layer 132, and the second n-type doping layer 133 are formed by changing the type of impurities in the source gas including silicon (Si). In this case, the source gas used may be a gas such as SiH ₄ , Si ₂ H ₆ , Si ₃ H ₈ , and the like for the plasma formation to decompose the source gas may be H ₂ , He and the like.

The gas for the p-type impurity is mixed with a gas (B ₂ H ₆ ) containing a trivalent element such as boron (B), and the gas for the n-type impurity includes a pentavalent element such as phosphorus (P). The gas (PH ₃ ) to mix.

As an example for forming the first p-type doped layer 131, a mixed gas obtained by adding H ₂ , B ₂ H _6, and CH ₄ to the source gas SiH ₄ is prepared under a pressure of about 0.5 Torr to 1 Torr. PECVD is performed at a radio frequency power of about 20W to 100W. In this case, the temperature of the substrate having the conductive transparent electrode 120 may be about 200 ° C.

In addition, as an example for forming the first intrinsic semiconductor layer 132 made of hydrogenated amorphous silicon (a-Si: H), H ₂ may be mixed with the source gas (SiH ₄ ) to about 0.5 Torr to 1 Torr. Under pressure, PECVD is performed at a high frequency power of about 20 to 50 W. The substrate temperature at this time may also be about 200 ° C.

As an example for forming the first n-type doped layer 133, H ₂ and PH ₃ are mixed with the source gas SiH ₄ to obtain a high frequency power of about 20 to 100 W under a pressure of about 0.5 Torr to 1 Torr. PECVD is performed. At this time, the substrate temperature may be about 200 ℃,

Next, the second p-type doping layer 141, the second intrinsic semiconductor layer 142, and the second n-type doping layer 143 are sequentially formed on the first photoelectric conversion unit 130 to form the second photoelectric conversion unit ( 140).

Similar to the first photoelectric conversion unit 130, the second photoelectric conversion unit 140 changes the type of impurities in the source gas containing silicon (Si) to form the second p-type doped layer 141 and the second intrinsic. The semiconductor layer 142 and the second n-type doped layer 143 may be formed.

The second p-type doped layer 141 may be made of hydrogenated microcrystalline silicon (μc-Si: H) or hydrogenated microcrystalline silicon oxide (μc-SiOx: H).

When the second p-type doped layer 141 is formed of hydrogenated fine crystal silicon oxide (μc-SiOx: H), as an example for forming the second p-type doped layer 141, the source gas (SiH ₄ ) After preparing a mixed gas in which H ₂ , B ₂ H _6, and Co ₂ were added, they were formed by PECVD at a high frequency power of about 20 to 100 W under a pressure of about 0.5 Torr to 1 Torr. In this case, the temperature of the substrate may be about 200 ° C.

In addition, as an example for forming the second intrinsic semiconductor layer 142 formed of hydrogenated microcrystalline silicon oxide (μc-SiOx: H), H ₂ and Co ₂ are mixed with the source gas (SiH ₄ ) to about 0.5. PECVD is performed at a high frequency power of about 20 W to 200 W under a pressure of Torr to 1 Torr. In this case, the substrate temperature may be about 200 ° C.

The second n-type doped layer 143 may be formed of hydrogenated microcrystalline silicon (μc-Si: H) or hydrogenated microcrystalline silicon oxide (μc-SiOx: H).

When the second n-type doped layer 143 is formed of hydrogenated microcrystalline silicon oxide (μc-SiOx: H), as an example for forming the second n-type doped layer 143, source gas (SiH ₄ ) H ₂ and PH ₃ are mixed with each other, and PECVD is performed at a high frequency power of about 20 W to 100 W under a pressure of about 0.5 Torr to 1 Torr. In this case, the substrate temperature may be about 200 ° C.

Next, the third p-type doping layer 151, the third intrinsic semiconductor layer 152, and the third n-type doping layer 153 are sequentially formed on the second photoelectric conversion unit 140 to form the third photoelectric conversion unit 150. ).

As an example for forming the third p-type doped layer 151, a mixed gas obtained by adding H ₂ , B ₂ H _6, and CO ₂ to the source gas SiH ₄ is prepared under a pressure of about 0.5 Torr to 1 Torr. PECVD is performed at a radio frequency power of about 20W to 100W. In this case, the temperature of the substrate 110 may be about 200 ° C.

In addition, as an example for forming the third intrinsic semiconductor layer 152 made of hydrogenated microcrystalline silicon (μc-Si: H), H ₂ is mixed with source gas (SiH ₄ ) to about 0.5 Torr to 1 Torr. Under pressure of PECVD at a high frequency power of about 20 to 50W. The substrate temperature at this time may also be about 200 ° C.

As an example for forming the third n-type doped layer 153, H ₂ and PH ₃ are mixed with the source gas SiH ₄ to obtain a high frequency power of about 20 to 100 W under a pressure of about 0.5 Torr to 1 Torr. PECVD is performed. At this time, the substrate temperature may be about 200 ℃,

When the silicon thin film solar cell includes the rear reflective layer 160, the rear reflective layer 160 is formed of a transparent conductive material such as aluminum oxide zinc oxide (ZnO: Al), and the rear electrode 170 is disposed on the rear reflective layer 160. ) To complete the solar cell.

When the silicon thin film solar cell includes the intermediate reflective layer 180, zinc oxide (ZnO) formed after forming the first photoelectric converter 130 and / or after forming the second photoelectric converter 140. The intermediate reflective layer 180 is formed of a transparent conductive material such as: Al).

The back electrode 170 may be formed of a conductive metal material, and may be formed of various materials according to the formation method thereof. For example, when the back electrode 170 is manufactured by screen printing, one selected from the group consisting of silver (Ag), aluminum (Al), and a combination thereof may be used, and an inkjet or dispensing method may be used. When manufactured with nickel (Ni), silver (Ag) and those selected from the group consisting of a combination thereof may be used.

In addition, when the back electrode 170 is formed by a plating method, one selected from the group consisting of nickel (Ni), copper (Cu), silver (Ag), and a combination thereof may be used. The back electrode 50 may be formed by a deposition method. In the case of forming, aluminum (Al), nickel (Ni), copper (Cu), silver (Ag), titanium (Ti), lead (Pd), chromium (Cr), tungsten (W) and combinations thereof Can be selected from. In addition, when the back electrode 170 is formed by screen printing, a mixture of silver (Ag) and a conductive polymer may be used.

In the above embodiments, the silicon thin film solar cell having the first to third photoelectric conversion units has been described. However, the present invention is applicable to a silicon thin film solar cell having four or more photoelectric conversion parts, when the photoelectric conversion part formed at an intermediate position has the same structure as the second photoelectric conversion part according to the above-described embodiment. For example, in the case of a quad-junction silicon thin film solar cell, the second photoelectric converter and / or the third photoelectric converter may be formed in the same structure as the second photoelectric converter according to the above-described embodiment.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

110: substrate 120: transparent electrode
130: first photoelectric converter 140: second photoelectric converter
150: third photoelectric conversion unit 160: rear reflective layer
170: rear electrode 180: intermediate reflective layer

Claims (16)

A substrate on which sunlight is incident; And
A first electrode, at least three photoelectric conversion parts, and a second electrode sequentially positioned on the substrate
Including,
The at least three photoelectric conversion parts include a first photoelectric conversion part, a second photoelectric conversion part, and a third photoelectric conversion part sequentially positioned on the first electrode,
The second photoelectric conversion unit includes a p-type doping layer, an intrinsic semiconductor layer, and an n-type doping layer, wherein the p-type doping layer and the n-type doping layer are hydrogenated microcrystalline silicon (μc-Si: H) or hydrogenated fine particles. A silicon thin film solar cell made of a material selected from crystalline silicon oxide (μc-SiOx: H), respectively, wherein the intrinsic semiconductor layer is formed of hydrogenated fine crystalline silicon oxide (μc-SiOx: H). In claim 1,
The silicon thin film solar cell having an oxygen content of 1% to 15% in the intrinsic semiconductor layer of the second photoelectric conversion part. In claim 2,
The intrinsic semiconductor layer of the first photoelectric conversion unit is a silicon thin film solar cell made of hydrogenated amorphous silicon (a-Si: H). In claim 2,
The intrinsic semiconductor layer of the third photoelectric conversion unit is a silicon thin film solar cell made of hydrogenated microcrystalline silicon (μc-Si: H). In claim 2,
The intrinsic semiconductor layer of the third photoelectric conversion unit is a silicon thin film solar cell made of hydrogenated microcrystalline silicon germanium (μc-SiGe: H). In claim 2,
At least one intermediate reflective layer is positioned between the first to third photoelectric conversion unit. In claim 1,
The intrinsic semiconductor layer of the second photoelectric conversion part has a crystallinity of 15% to 50%. In claim 7,
The intrinsic semiconductor layer of the first photoelectric conversion unit is a silicon thin film solar cell made of hydrogenated amorphous silicon (a-Si: H). In claim 7,
The intrinsic semiconductor layer of the third photoelectric conversion unit is a silicon thin film solar cell made of hydrogenated microcrystalline silicon (μc-Si: H). In claim 7,
The intrinsic semiconductor layer of the third photoelectric conversion unit is a silicon thin film solar cell made of hydrogenated microcrystalline silicon germanium (μc-SiGe: H). In claim 7,
At least one intermediate reflective layer is positioned between the first to third photoelectric conversion unit. A method of manufacturing a multi-junction solar cell having at least three photoelectric conversion parts,
Forming a first photoelectric converter on one surface of the substrate on which the first electrode is formed;
Forming a second photoelectric converter on the first photoelectric converter; And
Forming a third photoelectric converter on the second photoelectric converter
Including,
Forming the second photoelectric conversion unit,
Forming a p-type doped layer with any one selected from hydrogenated microcrystalline silicon (μc-Si: H) or hydrogenated microcrystalline silicon oxide (μc-SiOx: H);
Forming an intrinsic semiconductor layer from hydrogenated microcrystalline silicon oxide (μc-SiOx: H); And
Forming an n-type doped layer with any one selected from hydrogenated microcrystalline silicon (μc-Si: H) or hydrogenated microcrystalline silicon oxide (μc-SiOx: H)
Method for producing a silicon thin film solar cell comprising a. In claim 12,
Forming the first photoelectric conversion unit,
A method of manufacturing a silicon thin film solar cell comprising forming an intrinsic semiconductor layer over a first electrode with hydrogenated amorphous silicon (a-Si: H). In claim 12,
Forming the third photoelectric conversion unit,
A method of manufacturing a silicon thin film solar cell comprising forming an intrinsic semiconductor on a second photoelectric conversion portion with hydrogenated microcrystalline silicon (μc-Si: H). In claim 12,
Forming the third photoelectric conversion unit,
A method of manufacturing a silicon thin film solar cell comprising forming an intrinsic semiconductor layer on a second photoelectric conversion portion with hydrogenated microcrystalline silicon germanium (μc-SiGe: H). In claim 12,
And forming at least one intermediate reflective layer between the first to third photoelectric conversion parts.

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