KR101821392B1 - Thin film Solar cell - Google Patents

Abstract

The present invention relates to a thin film solar cell.
An example of a thin film solar cell according to the present invention includes a substrate; A first electrode disposed on the substrate; A second electrode disposed on the first electrode; And a photoelectric conversion section disposed between the first electrode and the second electrode and having at least one photoelectric conversion layer including a p-type semiconductor layer, an i-type semiconductor layer, and an n-type semiconductor layer, Type semiconductor layer of the semiconductor layer includes a first doping layer, a second doping layer, and a third doping layer, wherein the first doping layer includes amorphous silicon (a-Si), the second doping layer Microcrystalline silicon (mc-Si), and the third doping layer comprises microcrystalline silicon oxide (mc-SiO).

Description

Thin film solar cell {

The present invention relates to a thin film solar cell.

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

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

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

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

An example of a thin film solar cell according to the present invention includes a substrate; A first electrode disposed on the substrate; A second electrode disposed on the first electrode; And a photoelectric conversion section disposed between the first electrode and the second electrode and having at least one photoelectric conversion layer including a p-type semiconductor layer, an i-type semiconductor layer, and an n-type semiconductor layer, Type semiconductor layer of the semiconductor layer includes a first doping layer, a second doping layer, and a third doping layer, wherein the first doping layer includes amorphous silicon (a-Si), the second doping layer Microcrystalline silicon (mc-Si), and the third doping layer comprises microcrystalline silicon oxide (mc-SiO).

Here, the thickness of the first doping layer may be smaller than the thickness of the second doping layer and the third doping layer, and the thickness of the third doping layer may be equal to or greater than the thickness of the second doping layer.

In addition, the crystallinity of the second doping layer and the third doping layer may be 5% or more, and the content of oxygen (O) in the third doping layer may be between 45 at% and 65 at%.

The p-type semiconductor layer, the i-type semiconductor layer, and the n-type semiconductor layer included in the photoelectric conversion layer may be arranged in this order from the first electrode.

Here, the first doping layer, the second doping layer, and the third doping layer may be arranged in order from the i-type semiconductor layer of the photoelectric conversion layer.

The photoelectric conversion unit may include a first photoelectric conversion layer disposed between the first electrode and the second electrode, and the i-type semiconductor layer of the first photoelectric conversion layer may include amorphous silicon (a-Si).

Further, between the third doping layer and the second electrode, a back reflection layer may be further provided for reflecting the incident light toward the i-type semiconductor layer.

When the photoelectric conversion portion includes the first photoelectric conversion layer and the second photoelectric conversion layer which are arranged in order from the first electrode, the p-type semiconductor layer and the i-type semiconductor layer in the pin-type semiconductor layer of the first photoelectric conversion layer Type semiconductor layer of the first photoelectric conversion layer includes amorphous silicon material (a-Si), the pin-type semiconductor layer of the second photoelectric conversion layer includes a microcrystalline silicon material (mc-Si) Layer, a second doping layer, and a third doping layer.

In this case, an intermediate reflection layer for reflecting the incident light toward the i-type semiconductor layer of the first photoelectric conversion layer is further disposed between the third doped layer of the first photoelectric conversion layer and the p-type semiconductor layer of the second photoelectric conversion layer And the intermediate reflective layer may comprise at least one of aluminum-zinc-oxide (AZO) or boron-zinc-oxide (BZO).

In addition, a second doping layer may be further disposed between the third doped layer of the first photoelectric conversion layer and the p-type semiconductor layer of the second photoelectric conversion layer.

When the photoelectric conversion portion includes the first photoelectric conversion layer, the second photoelectric conversion layer, and the third photoelectric conversion layer arranged in order from the first electrode, the pinned semiconductor layer of the first photoelectric conversion layer is made of amorphous silicon material (a-Si), and the p-type semiconductor layer and the i-type semiconductor layer of the pin-type semiconductor layer of the second photoelectric conversion layer include amorphous silicon material (a-Si) The semiconductor layer may include a microcrystalline silicon material (mc-Si), and the n-type semiconductor layer of the second photoelectric conversion layer may include a first doping layer, a second doping layer, and a third doping layer.

In such a case, a first intermediate reflective layer for reflecting the incident light toward the i-type semiconductor layer of the first photoelectric conversion layer is formed between the n-th-doped layer of the first photoelectric conversion layer and the p-type semiconductor layer of the second photoelectric conversion layer And the first intermediate reflective layer may include at least one of aluminum-zinc-oxide (AZO) or boron-zinc-oxide (BZO) Type semiconductor layer of the second photoelectric conversion layer is further disposed between the third doped layer and the p-type semiconductor layer of the third photoelectric conversion layer, and the second intermediate reflective layer is formed of aluminum zinc And may include at least one of aluminum-zinc-oxide (AZO) or boron-zinc-oxide (BZO).

It is also possible that a second doping layer is further disposed between the third doped layer of the second photoelectric conversion layer and the p-type semiconductor layer of the third photoelectric conversion layer.

The photoelectric conversion portion includes a first photoelectric conversion layer, a second photoelectric conversion layer, and a third photoelectric conversion layer which are arranged in order from the first electrode, and the p-type semiconductor layer And the i-type semiconductor layer includes an amorphous silicon material (a-Si), the pin-type semiconductor layer of the second photoelectric conversion layer includes a microcrystalline silicon material (mc-Si) The semiconductor layer may include a microcrystalline silicon material (mc-Si), and the n-type semiconductor layer of the first photoelectric conversion layer may include a first doping layer, a second doping layer, and a third doping layer.

In the thin film solar cell according to the present invention, any one of the n-type semiconductor layers included in the photoelectric conversion layer includes the first doping layer, the second doping layer, and the third doping layer, And the conversion efficiency is improved.

1 is a view for explaining an example of a thin film solar cell according to the present invention.
2 is a view for explaining a first example of a double junction solar cell or pinpin structure according to the present invention.
FIG. 3 is a view for explaining the efficiency of the thin film solar cell shown in FIG. 2. FIG.
4 is a view for explaining a second example of a double junction solar cell or pinpin structure according to the present invention.
5 is a view for explaining a first example of a triple junction solar cell or pinpinpin structure according to the present invention.
6 is a view for explaining the efficiency of the thin film solar cell shown in FIG.
FIG. 7 is a view for explaining a second example of a triple junction solar cell or pinpinpin structure according to the present invention.
8 is a view for explaining a third example of a triple junction solar cell or pinpinpin structure according to the present invention.
9 is a view for explaining a fourth example of a triple junction solar cell or pinpinpin structure according to the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

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

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

As shown in FIG. 1, an example of a thin film solar cell according to the present invention includes a substrate 100, a first electrode 110, a photoelectric conversion unit (PV), and a second electrode 140.

Here, the substrate 100 can provide a space in which other functional layers can be disposed. In addition, the substrate 100 may be made of a substantially transparent nonconductive material, such as glass or plastic, so that the incident light can reach the photoelectric conversion unit PV more effectively.

The first electrode 110 is disposed under the substrate 100 and contains a substantially light-transmitting conductive material, for example, a transparent conductive oxide (TCO), in order to increase the transmittance of the incident light. In addition, the first electrode 110 may have a resistivity range of about 10 -2 Ω · cm to 10 11 Ω · cm. The first electrode 110 may be electrically connected to the photoelectric conversion unit PV. Accordingly, the first electrode 110 can collect and output one of the carriers generated by the incident light, for example, holes.

In addition, a plurality of irregularities having a pyramidal structure may be formed on the lower surface of the first electrode 110. That is, the first electrode 110 has a texturing surface. By texturing the surface of the first electrode 110 as described above, it is possible to reduce the reflection of the incident light and increase the light absorption rate, thereby improving the efficiency of the solar cell.

The second electrode 140 is disposed below the first electrode 110 and is disposed under the photoelectric conversion unit PV. In order to increase the recovery efficiency of the power generated by the photoelectric conversion unit PV, a metal material having excellent electrical conductivity . In addition, the second electrode 140 is electrically connected to the photoelectric conversion unit PV, and can collect and output one of the carriers generated by the incident light, for example, electrons.

The second electrode 140 may include at least one of silver (Ag) and aluminum (Al) having good electrical conductivity. The second electrode 140 may be a single layer or a multilayer.

In this case, the light is incident on the opposite side of the substrate 100, that is, the second electrode 140. In this case, the second electrode 140, And the first electrode 110 is formed of a metal material.

The photoelectric conversion unit PV is disposed between the first electrode 110 and the second electrode 140 and functions to convert light incident from the outside through the incident surface of the substrate 100 into electricity.

Such a photoelectric conversion portion PV may include at least one photoelectric conversion layer including a p-type semiconductor layer p, an i-type semiconductor layer i and an n-type semiconductor layer n.

1, when the photoelectric conversion layer is one, the photoelectric conversion layer is formed by stacking the p-type semiconductor layer p, the i-type semiconductor layer i and the n-type semiconductor layer n one by one .

In the case where the number of the photoelectric conversion layers is two, two photoelectric conversion layers may be included in each of the p-type semiconductor layer p, the i-type semiconductor layer i and the n-type semiconductor layer n. three p-type semiconductor layers p, i-type semiconductor layers i and n-type semiconductor layers n, respectively.

In FIG. 1, one photoelectric conversion layer is described as an example, and a case where two or three photoelectric conversion layers are described will be described later with reference to FIG. 2. FIG.

Thus, the p-type semiconductor layer p, the intrinsic (i-type) semiconductor layer i, and the n-type semiconductor layer n included in the photoelectric conversion layer are formed from the first electrode 110 to the p- , An intrinsic (i-type) semiconductor layer (i), and an n-type semiconductor layer (n).

Although the structure of the photoelectric conversion part PV is shown as a pin structure from the first electrode 110 in FIG. 1, the structure of the photoelectric conversion part PV is changed from the first electrode 110 to the nip structure It is also possible. However, for convenience of description, the structure of the photoelectric conversion portion PV is a p-i-n structure from the incident side will be described below as an example.

In the photoelectric conversion portion PV, the p-type semiconductor layer p is doped with a first type impurity such as boron (B, Baron), gallium (Ga), indium (In) ) Or the like can be used.

The n-type semiconductor layer n may be formed by doping a source gas containing silicon with impurities of a second type opposite to the first type such as phosphorus (P), arsenic (As), antimony (Sb) It can be formed using a gas containing an impurity.

The intrinsic (i) semiconductor layer (i) is disposed between the p-type semiconductor layer (p) and the n-type semiconductor layer (n) to reduce the recombination rate of carriers and absorb light. The i-type semiconductor layer (i) absorbs incident light and can generate carriers such as electrons and holes.

The i-type semiconductor layer i may be amorphous silicon containing carbon (C), or crystalline silicon containing carbon (C), and may be made of microcrystalline silicon (mc-SiC) containing carbon .

When the i-type semiconductor layer (i) contains carbon (C), the energy band gap can be made larger and the open-circuit voltage (Voc) can be improved.

The pin semiconductor layer p, i, n of the photoelectric conversion part PV may be formed by chemical vapor deposition (CVD) such as plasma enhanced chemical vapor deposition (PECVD) have.

1, a doping layer such as a p-type semiconductor layer p and an n-type semiconductor layer n of the photoelectric conversion portion PV is formed by a p-type semiconductor layer (i) Can be formed.

As shown in FIG. 1, a rear reflective layer 130 may be further included between the photoelectric conversion unit PV and the second electrode 140.

The rear reflective layer 130 is disposed between the photoelectric conversion unit PV and the second electrode 140 and reflects the light not absorbed by the photoelectric conversion unit PV to the photoelectric conversion unit PV do. That is, as shown in FIG. 1, the non-absorbed light from the photoelectric conversion unit PV is reflected toward the photoelectric conversion unit PV to increase the light absorption rate of the photoelectric conversion unit PV.

The refractive index of the rear reflective layer 130 at the interface with the photoelectric conversion unit PV may be lower than the refractive index at the interface with the rear electrode 140.

The rear reflection layer 130 may include any one of aluminum zinc oxide (ZnOx: Al), boron zinc oxide (ZnOx: B), and silicon oxide (SiOx).

The refractive index and electrical conductivity of the rear reflective layer 130 can be controlled by controlling the oxygen content of each material.

For example, when the rear reflective layer 130 includes aluminum zinc oxide (ZnOx: Al), the refractive index of the rear reflective layer 130 is the same as that of the front electrode 110, As shown in FIG.

As described above, the light reflected from the rear reflective layer 130 is absorbed by the photoelectric conversion unit PV, and some light is transmitted from the front electrode 110 to the photoelectric conversion unit PV ) Direction. The reflection between the front electrode 110 and the rear reflective layer 130 occurs several times at about 10 to 15 times so that the light is trapped.

In this way, the light absorptance of the photoelectric conversion unit PV can be increased, and thus the photoelectric conversion efficiency of the solar cell can be further improved.

In this structure, when light is incident on the p-type semiconductor layer (p), the p-type semiconductor layer (p) and the n-type semiconductor layer (n) having a relatively high doping concentration inside the i- A depletion is formed, whereby an electric field can be formed. Due to the photovoltaic effect, electrons and holes generated in the i-type semiconductor layer i, which is a light absorption layer, are separated by the contact potential difference and are moved in different directions. For example, the holes may move toward the front electrode 110 through the p-type semiconductor layer p and electrons may move toward the rear electrode 140 through the n-type semiconductor layer n. Power can be produced in this way.

On the other hand, only one n-type semiconductor layer (n) among the n-type semiconductor layers (n) included in the at least one photoelectric conversion layer includes the first doping layer n1, the second doping layer n2, (n3).

For example, as shown in FIG. 1, when there is one photoelectric conversion layer included in the photoelectric conversion portion PV, the n-type semiconductor layer n included in one photoelectric conversion layer may be a first doping layer n1, a second doping layer n2, and a third doping layer n3.

In the case where a plurality of photoelectric conversion layers are included in the photoelectric conversion portion PV, any one of the n-type semiconductor layers n included in the plurality of photoelectric conversion layers is formed in the first doped layer type semiconductor layer n1 may include a first doping layer n1, a second doping layer n2 and a third doping layer n3, and the remaining n-type semiconductor layer n may include a first doping layer n1, a second doping layer n2, And may not include the third doping layer n3. This will be described with reference to FIG.

Here, in FIG. 1, the case where one photoelectric conversion layer included in the photoelectric conversion portion PV is described is described as an example.

Here, the first doping layer n1, the second doping layer n2, and the third doping layer n3 may be arranged in order from the i-type semiconductor layer i.

More specifically, the first doping layer n1 is formed in contact with the i-type semiconductor layer i of the photoelectric conversion portion PV, and the second doping layer n2 is formed under the first doping layer n1 1 doped layer n1 and the third doped layer n3 may be formed in contact with the second doped layer n2 under the second doped layer n2.

The first doping layer n1 includes an amorphous silicon material (a-Si), the second doping layer n2 includes a microcrystalline silicon material (mc-Si), the third doping layer n3 ) Comprises a microcrystalline silicon material (mc-SiOx) containing oxygen (O).

When the i-type semiconductor layer i disposed on the first doping layer n1 includes an amorphous silicon material (a-Si) as shown in Fig. 1, the first doping layer n1 is made of amorphous silicon (A-Si), and it is possible to prevent the band gap from being abruptly changed and distorted.

More specifically, when the i-type semiconductor layer (i) contains an amorphous silicon material (a-Si), the first doping layer n1 of the amorphous silicon material (a- ) Is formed in contact with the i-type semiconductor layer (i), the photoelectric conversion layer of the pin structure may be distorted in the band gap due to the bonding of the dissimilar materials.

In such a case, the characteristics of the short-circuit current Jsc and the open-circuit voltage Voc may be degraded due to band gap distortion, which may be one of the factors that deteriorates the efficiency of the solar cell.

However, as in the present invention, when the first doping layer n1 includes an amorphous silicon material (a-Si), it is possible to prevent the band gap from being distorted.

Further, the second doping layer n2 and the third doping layer n3 include a microcrystalline silicon material (mc-Si), which can further improve the electrical conductivity characteristics of the n-type semiconductor layer (n).

That is, as described above, when the n-type semiconductor layer n is formed only of the amorphous silicon material (a-Si) in order to prevent the band gap from being distorted, banding of the band gap bending distortion can be prevented. However, the n-type semiconductor layer n can prevent the carrier from moving due to the low electrical conductivity, and the short-circuit current Jsc can be reduced.

However, when the second doping layer n2 formed in contact with the first doping layer n1 includes a microcrystalline silicon material (mc-Si) as in the present invention, the electrical conductivity characteristics can be further improved.

For example, in the case of the first doping layer n1 including the amorphous silicon material (a-Si), the electrical conductivity is very low, about 10 ^-8 S / cm2 to ^10-5 S / the second doped layer n2 and the third doped layer n3 including mc-Si are relatively higher than the first doped layer n1 with an electrical conductivity of 10 < ^-1 > S / It is possible to prevent the short circuit current Jsc from being reduced due to the layer n.

The photoelectric conversion portion PV includes two or more photoelectric conversion layers, and the photoelectric conversion layer including the amorphous silicon material (a-Si) and the microcrystalline silicon material (mc-Si) The second doping layer n2 including the microcrystalline silicon material mc-Si and the third doping layer n3 may be formed of the photoelectric conversion layer containing the amorphous silicon material (a-Si) It is possible to further improve the interfacial bonding properties of the two photoelectric conversion layers between the photoelectric conversion layers including the crystalline silicon material (mc-Si).

For this purpose, the degree of crystallization of the second doping layer n2 and the third doping layer n3 may be 5% or more in order to secure a minimum electrical conductivity characteristic.

As described above, the crystallinity of the second doping layer n2 and the third doping layer n3 is set to 5% or more because the electrical conductivity characteristics change greatly depending on the degree of crystallinity.

Specifically, as the crystallinity increases, the electrical conductivity characteristics increase exponentially. Therefore, it is preferable that the degree of crystallization of the second doping layer n2 and the third doping layer n3 is 5% or more so that the n-type semiconductor layer n has the minimum electrical conductivity.

In addition, the third doping layer n3 may include a microcrystalline silicon material (mc-SiO) containing oxygen.

Here, Si: O2 having two oxygen (O) atoms bonded to one silicon (Si) atom can be completely removed from the silicon (Si) It can not be used because it is nonconductor.

Since the third doping layer n3 contains oxygen O in the microcrystalline silicon material mc-Si, the refractive index of the third doping layer n3 is lower than that of the first doping layer n1 including the amorphous silicon material a-Si . For example, the refractive index of the third doping layer n3 may be between 1.5 and 2.5, thereby minimizing the light absorptance in the third doping layer n3 and increasing the reflectance relatively, Light is reflected by the i-type semiconductor layer (i), and the light absorption rate of the i-type semiconductor layer (i) can be further increased.

Thus, the third doping layer n3 has the effect of further increasing the short circuit current Jsc of the solar cell.

Here, the content of oxygen (O) contained in the third doping layer n3 affects the electrical conductivity and reflectance of the third doping layer n3.

Therefore, it is important to maximize the reflectivity of the third doping layer (n3) within a range in which the electrical conductivity characteristic of the third doping layer (n3) is not degraded.

In consideration of this, the content of oxygen (O) in the third doping layer (n3) may be between 45 at% and 65 at%.

Here, the oxygen (O) content of the third doping layer n3 is made to be 45 at% or more in order to secure the reflectance of the third doping layer n3 to the minimum, and that of the third doping layer n3 The oxygen (O) content is set to 65 at% or less in order to secure the reflectance of the third doped layer (n3) to a maximum extent within a range in which the electrical conductivity of the third doped layer (n3) is not degraded.

In addition, the thickness of the first doping layer n1 may be smaller than the thickness of the second doping layer n2 and the third doping layer n3.

This is because the first doping layer n1 functions to prevent the band gap characteristic of the photoelectric conversion layer formed in the pin structure from being distorted as described above, the thickness of the first doping layer n1 may be set to a value smaller than the thickness of the second doping layer n1 since the thickness of the second doping layer n2 is relatively low as compared with the thickness of the second doping layer n2 and the third doping layer n3. The thickness of the layer (n2) and the thickness of the third doping layer (n3).

In addition, the thickness of the third doping layer n3 may be equal to or greater than the thickness of the second doping layer n2.

For example, the thickness of the first doping layer n1 may be between 2.5 nm and 15 nm within a range smaller than the thicknesses of the second doping layer n2 and the third doping layer n3, the thickness of the second doping layer n2 may be between 10 nm and 30 nm and the thickness of the third doping layer n3 may be between 20 nm and 100 nm within a range larger than the thickness of the third doping layer n1.

As described above, the n-type semiconductor layer n of the photoelectric conversion layer according to the present invention includes the first doping layer n1, the second doping layer n2, and the third doping layer n3, ) And the open-circuit voltage (Voc) can be further improved, and the photoelectric conversion efficiency of the solar cell can be further improved.

Such a solar cell according to the present invention can further enhance its effect when a plurality of photoelectric conversion layers are provided.

For example, the case where one photoelectric conversion layer of the photoelectric conversion part PV is one has been described as an example, but a case where there are plural photoelectric conversion layers will be described as an example.

FIG. 2 is a view for explaining a first example of a double junction solar cell or a p-i-n-p-i-n structure according to the present invention.

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

As shown in FIG. 2, the thin film solar cell may include a first photoelectric conversion layer PV1 and a second photoelectric conversion layer PV2 arranged in order from the first electrode 110.

2, the thin film solar cell includes a first p-type semiconductor layer PV1-p, a first i-type semiconductor layer PV1-i, and a second p-type semiconductor layer PV1-p corresponding to the first photoelectric conversion layer PV1 from the first electrode 110, And the first n-type semiconductor layer PV1-n are sequentially stacked on the first photoelectric conversion layer PV2-p and the second p-type semiconductor layer PV2-p corresponding to the second photoelectric conversion layer PV2, -i and the second n-type semiconductor layer PV2-n may be sequentially stacked.

The first i-type semiconductor layer PV1-i can mainly absorb light in a short wavelength band to generate electrons and holes. In addition, the second i-type semiconductor layer (PV2-i) can mainly absorb light in a long wavelength band to generate electrons and holes.

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

In addition, the thickness of the second i-type semiconductor layer PV2-i may be thicker than the thickness of the first i-type semiconductor layer PV1-i to sufficiently absorb light in the long wavelength band.

2, the first p-type semiconductor layer PV1-p and the first i-type semiconductor layer PV1-i of the first photoelectric conversion layer PV1 are formed of amorphous silicon and the second p-type semiconductor layer PV2-p and the second i-type semiconductor layer PV2-i of the second photoelectric conversion layer PV2 may include microcrystalline silicon (mc-Si) ).

The solar cell having the double junction structure shown in Fig. 2 absorbs light of a short wavelength band in the first i-type semiconductor layer PV1-i to exert a photoelectric effect, and the second i-type semiconductor layer PV2- When the second i-type semiconductor layer PV2-i contains microcrystalline silicon (mc-SiC) as described above, a larger amount of long wavelength band (mc-SiC) The light can be absorbed and the efficiency of the solar cell can be improved.

On the other hand, in the solar cell having such a double junction structure, only the first n-type semiconductor layer (PV1-n) of the first photoelectric conversion layer (PV1), as shown in Fig. 2, The second n-type semiconductor layer (PV2-n) of the second photoelectric conversion layer PV2 includes a doping layer PV1-n1, a second doping layer PV1-n2 and a third doping layer PV1- ) May include the same microcrystalline silicon material (mc-Si) as the second i-type semiconductor layer (i) of the second photoelectric conversion layer PV2.

In this way, the efficiency of the solar cell can be further improved.

More specifically, as described above, the first doping layer PV1-n1 includes an amorphous silicon material (a-Si), the second doping layer PV1-n2 includes a microcrystalline silicon material (mc-Si ), And the third doping layer (PV1-n3) comprises a microcrystalline silicon oxide material (mc-SiOx).

In this case, the first doping layer PV1-n1 is formed in contact with the first i-type semiconductor layer i including the amorphous silicon material (a-Si) which is the same material as the first doping layer PV1-n1 The distortion of the band gap can be prevented in the first photoelectric conversion layer PV1 and the characteristics of the shortcircuit current Jsc and the open circuit voltage Voc can be further improved.

In addition, since the second doping layer PV1-n2 includes the microcrystalline silicon material (mc-Si), the electrical characteristics of the n-type semiconductor layer n can be further improved and the first doping layer PV1- n1) of the amorphous silicon material (a-Si) can be compensated to improve the electric conductivity. Therefore, the short-circuit current (Jsc) of the solar cell can be further improved.

In addition, the third doping layer PV1-n3 includes a microcrystalline silicon oxide material (mc-SiOx), and the refractive index can be significantly lowered than the first doping layer PV1-n1. Accordingly, incident light can be reflected by the first i-type semiconductor layer (i), and the light absorption rate of the first i-type semiconductor layer (i) can be further increased.

The second doping layer PV1-n2 including the microcrystalline silicon material mc-Si and the third doping layer PV1-n3 may be formed of a first photoelectric conversion layer containing amorphous silicon material (a-Si) It is possible to further improve the interfacial bonding property between the first photoelectric conversion layer PV1 including the microcrystalline silicon material (mc-Si) and the second photoelectric conversion layer PV2 including the microcrystalline silicon material (mc-Si).

The thin film solar cell having the double junction structure shown in FIG. 2 has a thickness of the first doping layer PV1-n1, the second doping layer PV1-n2 and the third doping layer PV1-n3 described above with reference to FIG. The oxygen content of the second doping layer PV1-n2, the crystallinity of the second doping layer PV1-n2, and the crystallinity of the third doping layer PV1-n3 may be applied as they are. The detailed description thereof is already described with reference to FIG. 1, so that further explanation is omitted.

FIG. 3 is a view for explaining the efficiency of the thin film solar cell shown in FIG. 2. FIG.

In FIG. 3, case 1 is a measurement value of the thin film solar cell of the present invention having the double junction structure shown in FIG. 2. In the thin film solar cell having the double junction structure of FIG. 2, (PV1-n1) are omitted.

3, an example of the thin film solar cell according to the present invention is different from the first comparative example in which the first doping layer PV1-n1 is omitted. The open-circuit voltage Voc, the short-circuit current Jsc, It can be seen that both the factor FF and the photoelectric conversion efficiency Eff are further improved.

As described above, the thin-film solar cell according to the present invention is more excellent in the open-circuit voltage (Voc) and the short-circuit current (Jsc) than the first comparative example, the first doping layer PV1-n1 for preventing gap distortion.

In addition, in the thin film solar cell having the double junction structure as described above, the first n-type doping layer of the first photoelectric conversion layer PV1 is formed of the first doping layer PV1-n1, the second doping layer PV1-n2, The third doped layer PV1-n3 of the first photoelectric conversion layer PV1 and the second photoelectric conversion layer PV2 of the first doped layer PV1-n3 are sequentially formed. A second doping layer PV1-n2 including a microcrystalline silicon material (mc-Si) may be further disposed between the second p-type semiconductor layers PV2-p.

The third doping layer PV1-n3 is formed by further disposing a second doping layer PV1-n2 including a microcrystalline silicon material (mc-Si) below the third doping layer PV1-n3, The oxygen of the third doping layer PV1-n3 is diffused into the second p-type semiconductor layer PV2-p of the second photoelectric conversion layer PV2 while the light reflection effect of the second p-type semiconductor layer PV2- It is possible to prevent the layer (p) from being contaminated.

Accordingly, the influence of the band gap of the second photoelectric conversion layer PV2 can be minimized.

In addition, the thin film solar cell having the double junction structure as described above may further include an intermediate reflective layer 120 between the first photoelectric conversion layer PV1 and the second photoelectric conversion layer PV2.

For example, FIG. 4 illustrates a second example of a double junction solar cell or a p-i-n-p-i-n structure according to the present invention.

The remaining portions of the thin film solar cell except for the intermediate reflection layer 120 in FIG. 4 are the same as those of the thin film solar cell shown in FIG. 2, so the description of the remaining portions will be omitted.

4, the thin film solar cell according to the present invention includes a third doped layer PV1-n3 of the first photoelectric conversion layer PV1 and a p-type semiconductor layer PV2 of the second photoelectric conversion layer PV2 p) of the first photoelectric conversion layer PV1 toward the i-type semiconductor layer PV1-i of the first photoelectric conversion layer PV1.

The material of the intermediate reflection layer 120 may include at least one of aluminum-zinc-oxide (AZO) and boron-zinc-oxide (BZO).

Accordingly, the third doping layer PV1-n3 including the microcrystalline silicon oxide material (mc-SiOx) may be formed of aluminum-zinc-oxide (AZO) or boron-zinc-oxide (BZO) The intermediate reflective layer 120 may include at least one of the intermediate reflective layer 120 and the intermediate reflective layer 120.

The intermediate reflection layer 120 is further formed between the third doped layer PV1-n3 of the first photoelectric conversion layer PV1 and the p-type semiconductor layer PV2-p of the second photoelectric conversion layer PV2 , The reflectivity of incident light can be further increased, and the light absorption rate of the first i-type semiconductor layer (PV1-i) can be further increased. Therefore, the photoelectric conversion efficiency of the entire photoelectric conversion portion PV can be further increased.

5 is a diagram illustrating a first example of a triple junction solar cell or a p-i-n-p-i-n-p-i-n structure according to the present invention.

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

5, in the thin film solar cell, the first photoelectric conversion layer PV1, the second photoelectric conversion layer PV2, and the third photoelectric conversion layer PV3 are sequentially arranged from the first electrode 110 .

The first photoelectric conversion layer PV1 is disposed closest to the first electrode 110 and the second photoelectric conversion layer PV2 is disposed closer to the first electrode 110 than the first photoelectric conversion portion PV. And the third photoelectric conversion layer PV3 is farther from the first electrode 110 than the second photoelectric conversion portion PV.

Each of the first photoelectric conversion layer PV1, the second photoelectric conversion layer PV2 and the third photoelectric conversion layer PV3 may be formed in a pin structure. The first p-type semiconductor layer (PV1-p), the first i-type semiconductor layer (PV1-i), the first n-type semiconductor layer (PV1- The second n-type semiconductor layer PV2-i, the second n-type semiconductor layer PV2-n, the third p-type semiconductor layer PV3-p, the third i-type semiconductor layer PV3- n may be arranged in this order.

The first p-type semiconductor layer PV1-p and the first i-type semiconductor layer PV1-i in the pin-shaped semiconductor layer of the first photoelectric conversion layer PV1 include an amorphous silicon material (a-Si) And the second p-type semiconductor layer (PV2-p) and the second i-type semiconductor layer (PV2-i) in the pin-shaped semiconductor layer of the second photoelectric conversion layer PV2 include an amorphous silicon material (a-Si) And the third p-type semiconductor layer PV3-p and the third i-type semiconductor layer PV3-i in the pin-shaped semiconductor layer of the third photoelectric conversion layer PV3 are made of a microcrystalline silicon material (mc-Si) And the second i-type semiconductor layer PV2-i of the second photoelectric conversion layer PV2 may further contain germanium (Ge).

In this case, the first i-type semiconductor layer PV1-i has the highest energy band gap and mainly absorbs light of a short wavelength, and the second i-type semiconductor layer PV2-i is made of amorphous silicon (a-Si) I-type semiconductor layer (PV3-i) because it contains germanium (Ge) and has an energy band gap lower than that of the first i-type semiconductor layer (PV1-i) Is composed of microcrystalline silicon (mc-Si), and thus has the lowest energy bandgap, so that light of long wavelength band is mainly absorbed.

Accordingly, the triple junction solar cell effectively absorbs light of a wider wavelength band than the double junction solar cell, and thus the photoelectric conversion efficiency is further improved.

The thickness of the third i-type semiconductor layer PV3-i is greater than the thickness of the second i-type semiconductor layer PV2-i, and the thickness of the second i- It may be thicker than the thickness of the semiconductor layer PV1-i. This is to further improve the light absorptance in the long wavelength band in the third i-type semiconductor layer (PV3-i).

As described above, in the case of the triple junction solar cell as shown in FIG. 5, since it can absorb light of a broader band, the power production efficiency can be high.

5, the first n-type semiconductor layer PV1-n of the first photoelectric conversion layer PV1 is connected to the first i-type semiconductor layer PV1-n of the first photoelectric conversion layer PV1 in the solar cell having the triple junction structure, The third n-type semiconductor layer n of the third photoelectric conversion layer PV3 includes the third i-type semiconductor layer n of the third photoelectric conversion layer PV3 and the amorphous silicon material (a-Si) And the second n-type semiconductor layer PV2-n of the second photoelectric conversion layer PV2 comprises the same microcrystalline silicon material (mc-Si) as the first doped layer PV2 -n1), a second doping layer (PV2-n2), and a third doping layer (PV2-n3).

In such a case, the characteristics of the short-circuit current (Jsc) and the open-circuit voltage (Voc) of the thin film solar cell can be further improved, and the photoelectric conversion efficiency can be further improved.

Detailed description thereof will be omitted because they are the same as those already described in Figs. 1 and 2 above.

In addition, the thin film solar cell having the triple junction structure shown in FIG. 3 has a structure in which the first doping layer PV2-n1, the second doping layer PV2-n2, and the third doping layer PV2- The oxygen content of the second doping layer PV2-n2, the crystallinity of the second doping layer PV2-n2 and the crystallinity of the third doping layer PV2-n3 can be applied as they are. The detailed description thereof is already described with reference to FIG. 1, so that further explanation is omitted.

6 is a view for explaining the efficiency of the thin film solar cell shown in FIG.

6 is a measurement of the thin film solar cell of the present invention having the triple junction structure shown in FIG. 5, and Comparative Example 2 is a value of the third doped layer of the thin film solar cell having the triple junction structure shown in FIG. (PV2-n3) is omitted.

6, the short-circuit current Jsc of the thin film solar cell according to the present invention is much higher than that of the comparative example 2 in which the third doping layer PV2-n3 is omitted, ) And the photoelectric conversion efficiency (Eff) are both further improved.

This is because the third thin film solar cell according to the present invention has a third doping layer (PV2-n3) having a light reflection function as compared with the second comparative example, as compared with the second comparative example.

More specifically, in the case of Comparative Example 1 in which the second n-type semiconductor layer PV2-n of the second photoelectric conversion layer PV2 does not include the third doping layer PV2-n3, the light reflection function is relatively low, It can be seen that the short-circuit current amount QE_Jsc of the second photoelectric conversion layer PV2 is 6.8 mA / cm2 relatively smaller than the short-circuit current amount QE_Jsc of the first photoelectric conversion layer PV1 or the second photoelectric conversion layer PV2 have.

Thus, in the thin film solar cell having a triple junction structure, three photoelectric conversion layers PV1, PV2, and PV3 are connected in the same manner as that connected in series, so that three photoelectric conversion layers PV1 and PV2 , And PV3, the amount of current of the photoelectric conversion layer that is lowest is determined as the value of the short circuit current Jsc of the photoelectric conversion unit PV, as shown in FIG. 6, when the short-circuit current of any one of the photoelectric conversion layers is relatively low.

In such a case, the thin film solar cell is reduced in both the fill factor (F.F) and the photoelectric conversion efficiency (Eff) due to the low short-circuit current (Jsc) value.

However, in the case where the second n-type semiconductor layer PV2-n of the second photoelectric conversion layer PV2 includes the third doping layer PV2-n3 as in the present invention, the second i-type semiconductor layer PV2 -i can be further improved and the amount of short circuit current QE_Jsc of the second photoelectric conversion layer PV2 relatively lower can be further increased and the short circuit current Jsc of the entire photoelectric conversion section PV can be increased. The value can be further improved, and thereby the fill factor (FF) and the photoelectric conversion efficiency (Eff) can be further improved.

5, the second n-type doped layer of the second photoelectric conversion layer PV2 is formed of three doped layers: a first doped layer (PV2-n1), a second doped layer The third doping layer PV2-n3 of the second photoelectric conversion layer PV2 is formed of the second doped layer PV2-n2 and the third doped layer PV2-n3, A second doping layer PV2-n2 including a microcrystalline silicon material (mc-Si) may be further disposed between the third p-type semiconductor layer PV3-p of the third photoelectric conversion layer PV3 .

Thus, the influence of the third photoelectric conversion layer PV3 on the band gap can be minimized.

In addition, the thin film solar cell having the triple junction structure as described above may further include a first intermediate reflective layer 120a between the first photoelectric conversion layer PV1 and the second photoelectric conversion layer PV2, And a second intermediate reflective layer 120b between the layer PV2 and the third photoelectric conversion layer PV3.

FIG. 7 is a view illustrating a triple junction solar cell or a second example of a p-i-n-p-i-n-p-i-n structure according to the present invention.

5, the remaining portion of the thin film solar cell except for the intermediate reflection layer is the same as that of the thin film solar cell shown in FIG. 5, so that the description of the remaining portions will be omitted.

7, in the thin film solar cell according to the present invention, between the n-th-doped layer of the first photoelectric conversion layer PV1 and the p-type semiconductor layer PV2-p of the second photoelectric conversion layer PV2, A first intermediate reflective layer 120a for reflecting the incident light in the direction of the i-type semiconductor layer PV1-i of the first photoelectric conversion layer PV1 is further disposed, Type semiconductor layer PV2 of the second photoelectric conversion layer PV2 is formed between the third p-type semiconductor layer PV3-p of the first photoelectric conversion layer PV2-n3 and the third p-type semiconductor layer PV3-p of the third photoelectric conversion layer PV3, the second intermediate reflective layer 120b may be further disposed.

The first intermediate reflective layer 120a and the second intermediate reflective layer 120b may include at least one of aluminum-zinc-oxide (AZO) or boron-zinc-oxide (BZO) have.

Therefore, the third doped layer PV2-n3 of the second photoelectric conversion layer PV2 including the microcrystalline silicon oxide material (mc-SiOx) is made of aluminum-zinc-oxide (AZO) or boron zinc oxide and a second intermediate reflective layer 120b including at least one of boron-zinc-oxide (BZO).

When the second intermediate reflective layer 120b is further formed between the third doping layer PV2-n3 and the third p-type semiconductor layer PV3-p, the reflectance of incident light can be further increased, The light absorption rate of the 2 i-type semiconductor layer (PV2-i) can be further increased. Therefore, the photoelectric conversion efficiency of the entire photoelectric conversion portion PV can be further increased.

FIG. 8 is a view for explaining a third example of a triple junction solar cell or a p-i-n-p-i-n-p-i-n structure according to the present invention.

In FIG. 8, the remaining parts are the same as those in FIG. 5 except for the changed parts in comparison with FIG. 5, so that a description thereof will be omitted and the changed parts will be mainly described.

8, the photoelectric conversion unit PV includes a first photoelectric conversion layer PV1, a second photoelectric conversion layer PV2, and a second photoelectric conversion layer PV2 arranged in order from the first electrode 110, And the third photoelectric conversion layer PV3. The p-type semiconductor layer PV1-p and the i-type semiconductor layer PV1-i in the pin-shaped semiconductor layer of the first photoelectric conversion layer PV1 are made of an amorphous silicon material the p-type semiconductor layer PV3-p and the i-type semiconductor layer PV3-i in the pin-shaped semiconductor layer of the third photoelectric conversion layer PV3 include the microcrystalline silicon material mc- Si).

8, in the pin-shaped semiconductor layer of the second photoelectric conversion layer PV2, the p-type semiconductor layer PV2-p and the i-type semiconductor layer PV2-i are fine Crystalline silicon material (mc-Si), and the i-type semiconductor layer (PV3-i) of the third photoelectric conversion layer (PV3) may further contain germanium (Ge).

8, the n-type semiconductor layer PV1-n of the first photoelectric conversion layer PV1 includes a first doping layer PV1-n1, a second doping layer PV1-n2, 3 doping layer (PV1-n3)

 The n-type semiconductor layer PV3-n of the second photoelectric conversion layer PV2 and the third photoelectric conversion layer PV3 is connected to the i-type semiconductor layer of the second photoelectric conversion layer PV2 and the third photoelectric conversion layer PV3, (Mc-Si), which is the same as PV2-i (PV2-i, PV3-i).

In addition, in the thin film solar cell having the triple junction structure as described above with reference to FIG. 8, the first n-type doped layer (PV1-n) of the first photoelectric conversion layer PV1 is divided into three doped layers, The first doping layer PV1-n1, the second doping layer PV1-n2, and the third doping layer PV1-n3 are sequentially formed. In addition, A second doping layer PV1-n2 including a microcrystalline silicon material (mc-Si) may be further disposed between the third doping layer PV1-n3 and the second p-type semiconductor layer PV2-p have.

FIG. 9 is a view for explaining a fourth example of a triple junction solar cell or a p-i-n-p-i-n-p-i-n structure according to the present invention.

The remaining portion of the thin film solar cell except for the intermediate reflection layer in FIG. 9 is the same as that of the thin film solar cell shown in FIG. 8, so that the description of the remaining portions will be omitted.

9, the thin film solar cell according to the present invention includes a third doped layer PV1-n3 of the first photoelectric conversion layer PV1 and a second p-type semiconductor layer of the second photoelectric conversion layer PV2, A first intermediate reflective layer 120a 'for reflecting the incident light toward the first i-type semiconductor layer PV1-i of the first photoelectric conversion layer PV1 is further disposed between the second intermediate reflective layer PV1-i and the second intermediate reflective layer 120a' The incident light is introduced between the second n-type semiconductor layer (PV2-n) of the photoelectric conversion layer (PV2) and the third p-type semiconductor layer (PV3-p) of the third photoelectric conversion layer (PV3) The second intermediate reflective layer 120b 'that reflects in the direction of the second i-type semiconductor layer PV2-i of the first intermediate reflective layer PV2 may be further disposed.

Here, the first intermediate reflective layer 120a 'and the second intermediate reflective layer 120b' are made of aluminum-zinc-oxide (AlN), as in the case of the first intermediate reflective layer 120a and the second intermediate reflective layer 120b described in FIG. oxide (AZO) or boron-zinc-oxide (BZO).

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

Claims (17)

Board;
A first electrode disposed on the substrate;
A second electrode disposed on the first electrode; And
And a photoelectric conversion portion disposed between the first electrode and the second electrode and including a first photoelectric conversion layer including a p-type semiconductor layer, an i-type semiconductor layer, and an n-type semiconductor layer,
The p-type semiconductor layer and the i-type semiconductor layer of the first photoelectric conversion layer each contain amorphous silicon (a-Si)
Wherein the n-type semiconductor layer of the first photoelectric conversion layer is a p-
A first doping layer which is in direct contact with the i-type semiconductor layer and contains amorphous silicon (a-Si) which is the same silicon material as the silicon material contained in the i-type semiconductor layer,
A second doping layer in contact with the first doping layer and containing microcrystalline silicon (mc-Si), which is a silicon material different from the silicon material contained in the i-type semiconductor layer and the first doping layer,
(Mc-SiOx) containing microcrystalline silicon and oxygen (O) in direct contact with said second doped layer and being the same silicon material as the silicon material contained in said second doped layer, A thin film solar cell comprising a doped layer. The method according to claim 1,
Wherein the thickness of the first doping layer is smaller than the thickness of the second doping layer and the third doping layer. 3. The method of claim 2,
And the thickness of the third doping layer is equal to or thicker than the thickness of the second doping layer. The method according to claim 1,
Wherein the second doping layer and the third doping layer have a degree of crystallinity of 5% or more, respectively. The method according to claim 1,
And the oxygen (O) content of the third doped layer is between 45 at% and 65 at%. The method according to claim 1,
Wherein the p-type semiconductor layer, the i-type semiconductor layer, and the n-type semiconductor layer included in the first photoelectric conversion layer are arranged in order from the first electrode. The method according to claim 1,
Wherein the first doping layer, the second doping layer, and the third doping layer are disposed in order from the i-type semiconductor layer of the first photoelectric conversion layer. delete The method according to claim 1,
And a backside reflective layer disposed between the third doping layer and the second electrode to reflect the incident light toward the i-type semiconductor layer. The method according to claim 1,
Wherein the photoelectric conversion unit further comprises a second photoelectric conversion layer positioned between the first photoelectric conversion layer and the second electrode,
And the pin-shaped semiconductor layer of the second photoelectric conversion layer comprises microcrystalline silicon (mc-Si). 11. The method of claim 10,
An intermediate reflection layer is formed between the third doped layer of the first photoelectric conversion layer and the p-type semiconductor layer of the second photoelectric conversion layer to reflect the incident light toward the i-type semiconductor layer of the first photoelectric conversion layer Further,
Wherein the intermediate reflective layer comprises at least one of aluminum-zinc-oxide (AZO) or boron-zinc-oxide (BZO). 11. The method of claim 10,
And the second doping layer is further disposed between the third doped layer of the first photoelectric conversion layer and the p-type semiconductor layer of the second photoelectric conversion layer. The method according to claim 1,
Wherein the photoelectric conversion unit further includes a second photoelectric conversion layer disposed between the first photoelectric conversion layer and the first electrode and a third photoelectric conversion layer disposed between the first photoelectric conversion layer and the second electrode,
The p-type semiconductor layer and the i-type semiconductor layer of the pin-type semiconductor layer of the second photoelectric conversion layer include amorphous silicon (a-Si)
Wherein the pin-shaped semiconductor layer of the third photoelectric conversion layer comprises microcrystalline silicon (mc-Si). [14] has been abandoned due to the registration fee. 14. The method of claim 13,
Type semiconductor layer of the second photoelectric conversion layer and the p-type semiconductor layer of the first photoelectric conversion layer in the direction of the i-type semiconductor layer of the second photoelectric conversion layer, A reflective layer is further disposed,
Wherein the first intermediate reflective layer comprises at least one of aluminum-zinc-oxide (AZO) or boron-zinc-oxide (BZO). [Claim 15 is abandoned upon payment of registration fee] 14. The method of claim 13,
Type semiconductor layer of the first photoelectric conversion layer to the i-type semiconductor layer of the first photoelectric conversion layer is formed between the third doped layer of the first photoelectric conversion layer and the p-type semiconductor layer of the third photoelectric conversion layer. A reflective layer is further disposed,
Wherein the second intermediate reflective layer comprises at least one of aluminum-zinc-oxide (AZO) or boron-zinc-oxide (BZO). 14. The method of claim 13,
And the second doping layer is further disposed between the third doped layer of the first photoelectric conversion layer and the p-type semiconductor layer of the third photoelectric conversion layer. The method according to claim 1,
The photoelectric conversion unit further includes a second photoelectric conversion layer positioned between the first photoelectric conversion layer and the second electrode and a third photoelectric conversion layer positioned between the second photoelectric conversion layer and the second electrode,
Wherein the pin-shaped semiconductor layer of the second photoelectric conversion layer includes microcrystalline silicon (mc-Si)
Wherein the pin-shaped semiconductor layer of the third photoelectric conversion layer comprises microcrystalline silicon (mc-Si).

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