JPWO2009144944A1 - Photoelectric conversion device - Google Patents

Abstract

The photoelectric conversion device of the present invention includes a first photoelectric conversion layer having an n-type semiconductor layer and a p-type semiconductor layer, an n-type semiconductor layer and a p-type semiconductor layer, and the first photoelectric conversion layer and the light absorption wavelength. It is sandwiched between a second photoelectric conversion layer having different characteristics, an n-type semiconductor layer of the first photoelectric conversion layer, and a p-type semiconductor layer of the second photoelectric conversion layer. The intermediate layer is a photoelectric conversion device laminated on a substrate. In the first photoelectric conversion layer, the intermediate layer approaches the electron energy level of the n-type semiconductor layer of the first photoelectric conversion layer and the hole energy level of the p-type semiconductor layer of the second photoelectric conversion layer. Metal oxide that changes the electron energy level of the n-type semiconductor layer in the vicinity of the interface with the intermediate layer or the hole energy level of the second photoelectric conversion layer in the vicinity of the interface with the intermediate layer of the p-type semiconductor layer Made of material. For this reason, tunnel conduction between layers is enhanced, and a highly efficient photoelectric conversion device can be realized.

Description

  The present invention relates to a photoelectric conversion device that converts light energy into electrical energy.

  As a photoelectric conversion device that converts light energy into electric energy, a stacked thin film solar cell in which a plurality of thin film photoelectric conversion layers having different light absorption wavelength characteristics are stacked is known. In such a conventional laminated thin film solar cell, for example, a plurality of elements each including a photoelectric conversion layer in which a thin film semiconductor is deposited in the order of a p-type layer, an i-type layer, and an n-type layer on an insulating transparent substrate on which a transparent electrode is formed. A reflective conductive film is formed as a back electrode, and a photovoltaic power is generated by light incidence from the insulating transparent substrate side.

Between each of the plurality of stacked photoelectric conversion elements, a conductive layer is inserted in order to transfer charges between the elements without delay. In this layer, a material having an optical characteristic of reflecting or transmitting light in a specific wavelength region is used. For example, Patent Document 1 discloses that ZnO, ITO, or SnO ₂ is used as a material for the intermediate layer.

JP 2006-120747 A

Conventionally, a translucent conductive film such as ZnO, ITO, or SnO ₂ is used in order to achieve both translucency and carrier conductivity. However, even when a conductive film made of these materials is used, if the current generated by the photoelectric conversion layer is high, the flowing current is limited by the resistance of the intermediate layer, which may reduce the light conversion efficiency of the photoelectric conversion device. .

  The present invention has been made in view of such circumstances, and provides a highly efficient photoelectric conversion device by improving conductivity between photoelectric conversion layers located on both sides of an intermediate layer in a stacked photoelectric conversion device. Objective.

  The photoelectric conversion device of the present invention includes a first photoelectric conversion layer having an n-type semiconductor layer and a p-type semiconductor layer, an n-type semiconductor layer and a p-type semiconductor layer, and the first photoelectric conversion layer and the light absorption wavelength. The second photoelectric conversion layer having different characteristics, the n-type semiconductor layer of the first photoelectric conversion layer, and the p-type semiconductor layer of the second photoelectric conversion layer are sandwiched between the second photoelectric conversion layer and the second photoelectric conversion layer. A photoelectric conversion device in which a light-transmitting intermediate layer whose main component in contact with the p-type semiconductor layer of the photoelectric conversion layer is aluminum oxide was stacked on a substrate was obtained.

  In addition, the photoelectric conversion device of the present invention includes a first photoelectric conversion layer having an n-type semiconductor layer and a p-type semiconductor layer, an n-type semiconductor layer and a p-type semiconductor layer, and the first photoelectric conversion layer and the light. The second photoelectric conversion layer having different absorption wavelength characteristics, the n-type semiconductor layer of the first photoelectric conversion layer, and the p-type semiconductor layer of the second photoelectric conversion layer have tunnel conductivity, and A photoelectric conversion in which an n-type semiconductor layer of the first photoelectric conversion layer and a translucent intermediate layer whose main component is hafnium oxide in contact with the p-type semiconductor layer of the second photoelectric conversion layer are stacked on the substrate Device.

  In the photoelectric conversion device of the present invention, the translucent intermediate layer whose main component in contact with the p-type semiconductor layer of the second photoelectric conversion layer is aluminum oxide, or the n-type semiconductor layer of the first photoelectric conversion layer and the first Since the main component in contact with the p-type semiconductor layer of the two photoelectric conversion layers has a translucent intermediate layer whose hafnium oxide is the electron energy of the n-type semiconductor layer of the first photoelectric conversion layer at the interface with the intermediate layer The level and the hole energy level of the p-type semiconductor layer of the second photoelectric conversion layer approach each other, and tunnel conduction between layers is enhanced. As a result of the enhancement of tunnel conduction, the conductivity between the first photoelectric conversion layer and the second photoelectric conversion layer is improved, and a highly efficient photoelectric conversion device can be realized.

It is sectional drawing which shows a part of cross section of the photoelectric conversion apparatus of Embodiment 1 of this invention. It is an energy conceptual diagram of the intermediate | middle layer of this invention, and the semiconductor layer joined to the both sides. It is sectional drawing which shows a part of cross section of the photoelectric conversion apparatus of Embodiment 2 of this invention. It is sectional drawing which shows a part of cross section of the photoelectric conversion apparatus of Embodiment 3 of this invention. It is sectional drawing which shows a part of cross section of the photoelectric conversion apparatus of Embodiment 4 of this invention. It is sectional drawing which shows a part of cross section of the photoelectric conversion apparatus of Embodiment 5 of this invention. It is sectional drawing which shows a part of cross section of the photoelectric conversion apparatus of Embodiment 6 of this invention.

  1 photoelectric conversion device, 2 substrate, 3 transparent electrode, 4 amorphous Si photoelectric conversion layer, 4a p-type amorphous SiC semiconductor layer, 4b i-type amorphous Si semiconductor layer, 4c n-type amorphous Si semiconductor layer 4d n-type amorphous Si semiconductor layer, 5 intermediate layer, 5a Si oxide layer, 5b aluminum oxide layer, 6 microcrystalline Si photoelectric conversion layer, 6a p-type microcrystalline Si semiconductor layer, 6b i-type microcrystalline Si semiconductor layer , 6c n-type microcrystalline Si semiconductor layer, 6d p-type microcrystalline Si semiconductor layer, 7 back electrode, 8 undercoat, 11 transparent conductive layer, 301, 304 intermediate layer, 302 n-type semiconductor layer, 303 p-type semiconductor layer.

<Embodiment 1>
FIG. 1 is a cross-sectional view illustrating a part of a cross section of the photoelectric conversion device according to the first embodiment. The photoelectric conversion device 1 is an insulating and transparent substrate 2, a transparent electrode 3 having a surface texture structure that is fine irregularities thereon, an amorphous Si photoelectric conversion layer 4, an intermediate layer 5, a microcrystalline Si photoelectric conversion The layer 6 and the back electrode 7 are provided in order. An Si oxide undercoat 8 as shown may be applied on the substrate 2 as an impurity blocking layer as required.

  Both the amorphous Si photoelectric conversion layer 4 and the microcrystalline Si photoelectric conversion layer 6 are mainly composed of Si, but have different band gaps depending on the crystal structure, and thus have different light absorption wavelength characteristics. The photoelectric conversion device 1 of the first embodiment is a device that converts light incident mainly from the substrate side into electricity using a transparent substrate 2. The power generation element of the amorphous Si photoelectric conversion layer 4 and the power generation element of the microcrystalline Si photoelectric conversion layer 6 are connected in series in the stacking direction, and the current generated in each photoelectric conversion layer is transferred to the transparent electrode 3 and the back electrode 7. It is the structure taken out from. Such a photoelectric conversion device is known as a tandem solar cell. In tandem solar cells, in general, a photoelectric conversion layer with a large band gap that absorbs light with a short wavelength on the light incident side and converts it into electrical energy, and a light with a wavelength longer than the former on the back side. A photoelectric conversion layer having a small band gap for conversion into electric energy is disposed. As the photoelectric conversion layer having different light absorption wavelength characteristics, materials having different crystallization rates from the amorphous Si layer and the microcrystalline Si layer are used in the first embodiment, but layers having different element compositions may be used. For example, the photoelectric conversion layer may be adjusted to have different light absorption wavelength characteristics by changing the ratio of Ge or C added to the Si semiconductor layer to adjust the band gap. In addition, three or more photoelectric conversion layers may be stacked. In that case, it is good also as a structure which has two or more so that an intermediate | middle layer may exist between each photoelectric converting layer. Alternatively, the stacking order from the substrate may be reversed, and light may be incident from the film surface side opposite to the substrate. When light is incident from the film surface side, the substrate does not have to be transparent.

  The amorphous Si photoelectric conversion layer 4 is a layer in which a p-type amorphous SiC semiconductor layer 4a, an i-type amorphous Si semiconductor layer 4b, and an n-type amorphous Si semiconductor layer 4c are stacked in this order from the substrate side. Has been. Further, an i-type amorphous SiC semiconductor layer may be inserted between the p-type amorphous SiC semiconductor layer 4a and the i-type amorphous Si semiconductor layer 4b. The microcrystalline Si photoelectric conversion layer 6 is composed of a layer in which a p-type microcrystalline Si semiconductor layer 6a, an i-type microcrystalline Si semiconductor layer 6b, and an n-type microcrystalline Si semiconductor layer 6c are stacked in this order from the substrate side. .

  For the back electrode 7, for example, a metal having high reflectivity such as Al or Al alloy is used. Ag may be used instead of Al. When the back electrode 7 having excellent reflection performance is used, the light transmitted through the microcrystalline Si photoelectric conversion layer 6 is reflected again by the back electrode 7 toward the microcrystalline Si photoelectric conversion layer 6 and is photoelectrically converted, thereby improving the conversion efficiency. To do. A transparent conductive layer 11 such as ZnO having appropriate optical characteristics is provided between the back electrode 7 and the n-type microcrystalline Si semiconductor layer 6c as shown in FIG. It may be inserted.

  The intermediate layer 5 is a layer sandwiched between the amorphous Si photoelectric conversion layer 4 and the microcrystalline Si photoelectric conversion layer 6. The intermediate layer 5 transmits light that has not been absorbed by the amorphous Si photoelectric conversion layer 4 to the microcrystalline Si photoelectric conversion layer 6 side. Conduct electricity between them. The intermediate layer 5 transmits light in the wavelength region absorbed by the microcrystalline Si photoelectric conversion layer 6, while the light in the wavelength region absorbed by the amorphous Si photoelectric conversion layer 4 transmits the light in the amorphous Si photoelectric conversion layer 4 side. If the optical characteristic is reflected, the light passing through the amorphous Si photoelectric conversion layer 4 passes through the amorphous Si photoelectric conversion layer 4 again and undergoes photoelectric conversion, so that the conversion efficiency is improved.

  Since the intermediate layer 5 has to transmit carriers between photoelectric conversion layers bonded to both sides of the layer without any delay, carrier conductivity is essential. When carrier conduction is hindered between the photoelectric conversion layers, the effective inter-element connection resistance is increased, and the fill factor (FF) of the solar cell is decreased, resulting in a decrease in power generation efficiency. Therefore, the intermediate layer must satisfy both the transmittance and the carrier conductivity.

In the first embodiment, the structure of the intermediate layer 5 is mainly composed of an oxide Si layer 5a on the amorphous Si photoelectric conversion layer 4 side and an aluminum oxide such as Al ₂ O ₃ on the opposite microcrystalline Si photoelectric conversion layer 6 side. It was set as the 2 layer structure used as the aluminum oxide layer 5b contained in a component. The layer 5b may be a layer having oxygen vacancies, such as AlO _x (X-1 to 1.5). The Si oxide layer 5a and the aluminum oxide layer 5b can be formed by sputtering or CVD. Impurities such as phosphorus and boron may be added to the oxidized Si layer 5a. Further, it may be a layer formed by oxidizing the surface of the amorphous Si photoelectric conversion layer by exposure to an atmosphere of strong oxidizing ozone gas or active oxygen. A metal other than Al may be added to the aluminum oxide layer 5b as long as it mainly contains Al as a metal element. Further, elements such as Si, phosphorus, and boron may be included. The aluminum oxide layer 5b may be formed by once forming metal aluminum on the oxidized Si layer 5a and then oxidizing it. A ZnO layer or a hafnium oxide compound (HfO ₂ ) layer may be used instead of the Si oxide layer 5a.

  In the intermediate layer 5, current flows between the amorphous Si photoelectric conversion layer 4 and the microcrystalline Si photoelectric conversion layer 6 mainly by tunnel conduction and carrier recombination. The Si oxide layer 5a and the aluminum oxide layer 5b constituting the intermediate layer 5 of the first embodiment are basically insulating materials, but a tunnel current flows by making them sufficiently thin. For example, the thickness may be about 1 to 10 nm. Moreover, it is desirable that the Si oxide layer 5a and the aluminum oxide layer 5b constituting the intermediate layer 5 are continuous films. However, it is only necessary to cover the respective interfaces. It may be a film having

  Next, the operation of such an intermediate layer 5 will be described. In the photoelectric conversion device configured as described above, positive charges are held in the Si oxide layer 5a of the intermediate layer 5, and negative charges are held in the aluminum oxide layer 5b. It is known that an oxide film such as Si oxide tends to be positively charged. On the other hand, aluminum oxide is known to have a tendency to hold negative charges, unlike an oxide film such as Si oxide. For example, the trend is described in the document Journal of Applied Physics, Volume 102, 054513 (page 3, line 13). Therefore, electrons are present near the interface between the n-type amorphous Si semiconductor layer 4c and the oxidized Si layer 5a in the amorphous Si photoelectric conversion layer 4 in contact with the oxidized Si layer 5a. Holes are accumulated in the vicinity of the interface between the type microcrystalline Si semiconductor layer 6a and the aluminum oxide layer 5b. This reduces the difference between the conduction band energy of the n-type amorphous Si semiconductor layer 4c in the amorphous Si photoelectric conversion layer and the valence band energy of the p-type microcrystalline Si semiconductor layer 6a in the microcrystalline Si photoelectric conversion layer. This improves the efficiency of tunnel conduction and carrier recombination between the photoelectric elements.

FIG. 2 is an energy conceptual diagram of the conduction band and valence band of the intermediate layer 5 and the n-type semiconductor layer and the p-type semiconductor layer bonded to both sides thereof. 2A is a conceptual diagram in the case of using a conventional material such as ZnO, ITO, or SnO ₂ , and FIG. 2B is a conceptual diagram in the case of the first embodiment. The dotted line in the figure indicates the Fermi level. In the conventional case (a), the conduction band energy (Ec, n), valence band energy (Ev, n) of the n-type semiconductor layer 302 located on both sides of the intermediate layer 301, and the conduction band energy of the p-type semiconductor layer 303. The energy level of (Ec, p) and valence band energy (Ev, p) does not change even in the vicinity of the intermediate layer 5. On the other hand, in (b) of the first embodiment, the p-type microcrystalline Si semiconductor layer 6a side is the aluminum oxide layer 5b, and the n-type amorphous Si semiconductor layer 4c is a dielectric layer such as the Si oxide layer 5a. As a result, the inclination of the energy level of the n-type semiconductor layer and the p-type semiconductor layer changes in the vicinity of the interface with the intermediate layer 304 due to the difference in charge and hole accumulation tendency of each layer, and the n-type semiconductor layer 302 is changed. The conduction band energy (Ec, n) of the p-type semiconductor layer 303 approaches that of the conduction band energy (Ec, n). That is, the respective energy levels change so that the electron energy level of the n-type semiconductor layer and the hole energy level of the p-type semiconductor layer approach each other in the vicinity of the interface between the junction layers of the semiconductor layers and the intermediate layer. Thus, when the energy gap between the n-type conduction band and the p-type layer valence band is small, tunnel conduction between layers is enhanced, carrier recombination is enhanced, and current flows easily.

  As described above, in the first embodiment, as the intermediate layer 5, the side in contact with the interface with the p-type microcrystalline Si semiconductor layer 6a is the aluminum oxide layer 5b, and the interface with the n-type amorphous Si semiconductor layer 4c. By making the contact side a dielectric layer such as the oxidized Si layer 5a, the electron energy level of the n-type semiconductor layer and the hole energy level of the p-type semiconductor layer are close to each other. A tunnel current easily flows between the crystalline Si semiconductor layer 4c, and as a result, the efficiency of the photoelectric conversion device is improved.

If the p-type microcrystalline Si semiconductor layer 6a side is a layer 5b containing aluminum oxide as a main component, the n-type amorphous Si semiconductor layer 4c is composed of ZnO and hafnium oxide compounds (HfO) instead of the Si oxide layer 5a. Similar effects can be obtained by using a dielectric material such as ₂ ). The intermediate layer 5 has two layers of the aluminum oxide compound layer 5b and the Si oxide layer 5a. However, the intermediate layer 5 may have a gradient composition structure in which the composition sequentially changes from the aluminum oxide compound to the Si oxide in the thickness direction. .

<Embodiment 2>
FIG. 3 is a cross-sectional view showing a part of a cross section of the photoelectric conversion device according to the second embodiment. The photoelectric conversion device according to the second embodiment basically has the same structure except that the intermediate layer 5 of the photoelectric conversion device according to the first embodiment is a single layer containing aluminum oxide as a main component. .

  Since aluminum oxide tends to hold negative charges, the microcrystalline Si photoelectric conversion layer 6 in contact with the intermediate layer 5 even when the intermediate layer 5 is a single layer composed of an aluminum oxide compound. Holes are accumulated near the interface of the p-type microcrystalline Si semiconductor layer 6a. This changes the inclination of the hole energy level in the vicinity of the interface between the p-type microcrystalline Si semiconductor layer 6a and the intermediate layer 5, and the conduction of the n-type amorphous Si semiconductor layer 4c in the amorphous Si photoelectric conversion layer. The difference between the band energy and the valence band energy of the p-type microcrystalline Si semiconductor layer 6a in the microcrystalline Si photoelectric conversion layer is reduced. As a result, the tunnel conduction between the photoelectric elements and the efficiency of carrier recombination are improved, the effective connection resistance between the photoelectric conversion layers is lowered, and a photoelectric conversion device with high power generation efficiency can be realized. The first embodiment having a two-layer structure is superior in terms of the action of bringing the energy between the photoelectric conversion layers closer, but the manufacturing is easy because the film structure may be one layer.

<Embodiment 3>
FIG. 4 is a cross-sectional view showing a part of a cross section of the photoelectric conversion device according to the third embodiment. The photoelectric conversion device of the present third embodiment basically has the same structure except that the main component of the intermediate layer 5 of the photoelectric conversion device of the second embodiment is made of hafnium oxide instead of aluminum oxide.

  The hafnium oxide of the intermediate layer 5 can be formed by sputtering or CVD. A metal other than hafnium may be added to hafnium oxide. Moreover, it is sufficient to contain a hafnium oxide as a main component. For example, a material such as nitrogen-added hafnium silicate (HfSiON) may be used. Further, it is desirable that the thickness of the intermediate layer 5 be sufficiently thin in order to cause tunnel conduction.

  Such a hafnium oxide is known as a substance that causes the phenomenon of Fermi level pinning at the interface with the Si semiconductor. The Fermi level is usually located near the conduction band in n-type polycrystalline Si and near the valence band in p-type polycrystalline Si. Fermi level pinning is a method in which a hafnium oxide thin film is sandwiched between n-type polycrystalline Si and p-type polycrystalline Si and has a structure in contact with each interface. This is a phenomenon in which polycrystalline Si and p-type polycrystalline Si Fermi levels are attracted to almost the same position as if they were pinned. In the case of the third embodiment, the Fermi level of the n-type amorphous Si semiconductor layer 4c in the amorphous Si photoelectric conversion layer 4 and the p-type microcrystalline Si semiconductor layer in the microcrystalline Si photoelectric conversion layer 6 are used. The energy difference at the Fermi level of 6a approaches 0.2 eV. This improves the efficiency of conduction and carrier recombination between the n-type amorphous Si semiconductor layer 4c in the amorphous Si photoelectric conversion layer and the p-type microcrystalline Si semiconductor layer 6a in the microcrystalline Si photoelectric conversion layer. As a result, the effective connection resistance between the photoelectric elements decreases, and a photoelectric conversion device with high power generation efficiency can be realized.

<Embodiment 4>
FIG. 5 is a cross-sectional view showing a part of the cross section of the photoelectric conversion device according to the fourth embodiment. The photoelectric conversion device according to the fourth embodiment has a carrier density higher than that of the n-type amorphous Si semiconductor layer 4c between the intermediate layer 5 and the n-type amorphous Si semiconductor layer 4c of the photoelectric conversion device according to the first embodiment. By inserting a high n-type amorphous Si semiconductor layer 4d, p-type microcrystalline Si having a carrier density higher than that of the p-type microcrystalline Si semiconductor layer 6a between the intermediate layer 5 and the p-type microcrystalline Si semiconductor layer 6a. The structure is basically the same except that the semiconductor layer 6d is inserted.

  The semiconductor layer in contact with the intermediate layer 5 is depleted near the interface of the intermediate layer due to the influence of the intermediate layer potential. In the depleted region (hereinafter referred to as a depletion layer), the number of carriers contributing to conduction is reduced, and thus the resistance is increased. Therefore, there is a possibility of causing an increase in effective connection resistance. The depletion layer thickness decreases as the carrier concentration of the semiconductor layer increases. Accordingly, it is desirable that the carrier density is high in order to reduce the depletion layer thickness.

  However, when the carrier density of the semiconductor layer is high, light absorption in the semiconductor layer increases. In the photoelectric element, light absorbed by the n-type semiconductor layer and the p-type semiconductor layer does not contribute to current generation. Therefore, from the viewpoint of light absorption, it is desirable that the n-type and p-type semiconductor layers have a low carrier density.

In the fourth embodiment, since the carrier density of the n-type and p-type semiconductor layers is increased only in the vicinity of the intermediate layer, light absorption in the n-type and p-type semiconductor layers can be suppressed as much as possible while suppressing the extension of the depletion layer. It becomes possible. For example, in Si, when the carrier density is about 1E19 / cm ³ , the depletion layer thickness is about 1 nm. Therefore, it is considered that the carrier density of the n-type semiconductor layer 4d and the p-type semiconductor layer 6d is preferably 1E19 / cm ³ or more. . Thereby, an effective connection resistance between the photoelectric elements can be reduced, and a photoelectric conversion device that does not reduce the generated current can be realized.

<Embodiment 5>
FIG. 6 is a cross-sectional view showing a part of the cross section of the photoelectric conversion device of the fifth embodiment. The photoelectric conversion device of the fifth embodiment has a carrier density higher than that of the n-type amorphous Si semiconductor layer 4c between the intermediate layer 5 and the n-type amorphous Si semiconductor layer 4c of the photoelectric conversion device of the second embodiment. By inserting a high n-type amorphous Si semiconductor layer 4d, p-type microcrystalline Si having a carrier density higher than that of the p-type microcrystalline Si semiconductor layer 6a between the intermediate layer 5 and the p-type microcrystalline Si semiconductor layer 6a. The structure is basically the same except that the semiconductor layer 6d is inserted. The intermediate layer 5 is a single layer containing aluminum oxide as a main component.

  As in the fourth embodiment, in the fifth embodiment, the carrier density of the n-type and p-type semiconductor layers is increased only in the vicinity of the intermediate layer, so that light in the n-type and p-type semiconductor layers is suppressed while suppressing the extension of the depletion layer. It is possible to suppress absorption as much as possible. Thereby, an effective connection resistance between the photoelectric elements can be reduced, and a photoelectric conversion device that does not reduce the generated current can be realized.

<Embodiment 6>
FIG. 7 is a cross-sectional view showing a part of a cross section of the photoelectric conversion device according to the sixth embodiment. The photoelectric conversion device of the sixth embodiment has a carrier density higher than that of the n-type amorphous Si semiconductor layer 4c between the intermediate layer 5 and the n-type amorphous Si semiconductor layer 4c of the photoelectric conversion device of the third embodiment. By inserting a high n-type amorphous Si semiconductor layer 4d, p-type microcrystalline Si having a carrier density higher than that of the p-type microcrystalline Si semiconductor layer 6a between the intermediate layer 5 and the p-type microcrystalline Si semiconductor layer 6a. The structure is basically the same except that the semiconductor layer 6d is inserted. The intermediate layer 5 is a layer mainly composed of hafnium oxide.

  As in the fourth embodiment, in the sixth embodiment as well, the carrier density of the n-type and p-type semiconductor layers is increased only in the vicinity of the intermediate layer. It is possible to suppress absorption as much as possible. Thereby, an effective connection resistance between the photoelectric elements can be reduced, and a photoelectric conversion device that does not reduce the generated current can be realized.

  As described in the above embodiments, in the photoelectric conversion device of the present invention, the first photoelectric conversion layer and the second photoelectric conversion layer each having an n-type semiconductor layer and a p-type semiconductor layer and having different light absorption wavelength characteristics from each other. The conversion layer is stacked, and has a light-transmitting intermediate layer between the n-type semiconductor layer of the first photoelectric conversion layer and the p-type semiconductor layer of the second photoelectric conversion layer, and the conversion layer is formed at the interface with the intermediate layer. The middle of the n-type semiconductor layer of the first photoelectric conversion layer so that the electron energy level of the n-type semiconductor layer of the first photoelectric conversion layer and the hole energy level of the p-type semiconductor layer of the second photoelectric conversion layer are close to each other. The electron energy level in the vicinity of the interface with the layer or the hole energy level in the vicinity of the interface with the intermediate layer of the p-type semiconductor layer of the second photoelectric conversion layer changes. For this reason, the effective connection resistance between the n-type semiconductor layer of the first photoelectric conversion layer and the p-type semiconductor layer of the second photoelectric conversion layer sandwiching the intermediate layer is reduced, and the photoelectric conversion device having high power generation efficiency Can be realized. The configuration of the above embodiment is particularly suitable for improving the conversion efficiency of a photoelectric conversion layer made of a semiconductor layer containing Si as a main component.

  In a photoelectric conversion device that converts light energy into electrical energy, the conductivity between the photoelectric conversion layers located on both sides of the intermediate layer can be improved, and a highly efficient photoelectric conversion device can be provided.

The photoelectric conversion device of the present invention includes a first photoelectric conversion layer having an n-type semiconductor layer and a p-type semiconductor layer, an n-type semiconductor layer and a p-type semiconductor layer, and the first photoelectric conversion layer and the light absorption wavelength. Tunnel conductivity with a thickness of 1 to 10 nm sandwiched between a second photoelectric conversion layer having different characteristics, an n-type semiconductor layer of the first photoelectric conversion layer, and a p-type semiconductor layer of the second photoelectric conversion layer And a photoelectric conversion device in which a translucent intermediate layer in which the main component in contact with the p-type semiconductor layer of the second photoelectric conversion layer is aluminum oxide holding negative charges is laminated on a substrate. .

In addition, the photoelectric conversion device of the present invention includes a first photoelectric conversion layer having an n-type semiconductor layer and a p-type semiconductor layer, an n-type semiconductor layer and a p-type semiconductor layer, and the first photoelectric conversion layer and the light. Tunnel conduction with a thickness of 1 to 10 nm sandwiched between a second photoelectric conversion layer having different absorption wavelength characteristics, an n-type semiconductor layer of the first photoelectric conversion layer, and a p-type semiconductor layer of the second photoelectric conversion layer And a translucent intermediate layer whose main component contacting the n-type semiconductor layer of the first photoelectric conversion layer and the p-type semiconductor layer of the second photoelectric conversion layer is hafnium oxide. And a photoelectric conversion device stacked on each other.
In addition, the photoelectric conversion device of the present invention includes a first photoelectric conversion layer having an n-type semiconductor layer and a p-type semiconductor layer, an n-type semiconductor layer and a p-type semiconductor layer, and the first photoelectric conversion layer and the light. Tunnel conduction with a thickness of 1 to 10 nm sandwiched between a second photoelectric conversion layer having different absorption wavelength characteristics, an n-type semiconductor layer of the first photoelectric conversion layer, and a p-type semiconductor layer of the second photoelectric conversion layer And the main components in contact with the n-type semiconductor layer of the first photoelectric conversion layer and the p-type semiconductor layer of the second photoelectric conversion layer are Fermi levels of the n-type semiconductor layer, the p-type semiconductor layer, and Fermi A photoelectric conversion device in which an intermediate layer made of a light-transmitting material having a Fermi level pinning phenomenon that draws the level to substantially the same position is laminated on the substrate.

The intermediate layer 5 is a layer sandwiched between the amorphous Si photoelectric conversion layer 4 and the microcrystalline Si photoelectric conversion layer 6. The intermediate layer 5 transmits light not absorbed by the amorphous Si photoelectric conversion layer 4 to the microcrystalline Si photoelectric conversion layer 6 side, and at the same time, passes between the microcrystalline Si photoelectric conversion layer 6 and the microcrystalline Si photoelectric conversion layer 6. Conduct electricity. The intermediate layer 5 transmits light in the wavelength region absorbed by the microcrystalline Si photoelectric conversion layer 6, while the light in the wavelength region absorbed by the amorphous Si photoelectric conversion layer 4 transmits the light in the amorphous Si photoelectric conversion layer 4 side. If the optical characteristic is reflected, the light passing through the amorphous Si photoelectric conversion layer 4 passes through the amorphous Si photoelectric conversion layer 4 again and undergoes photoelectric conversion, so that the conversion efficiency is improved.

The photoelectric conversion device of the present invention includes a first photoelectric conversion layer having an n-type semiconductor layer and a p-type semiconductor layer, an n-type semiconductor layer and a p-type semiconductor layer, and the first photoelectric conversion layer and the light absorption wavelength. Tunnel conductivity with a thickness of 1 to 10 nm sandwiched between a second photoelectric conversion layer having different characteristics, an n-type semiconductor layer of the first photoelectric conversion layer, and a p-type semiconductor layer of the second photoelectric conversion layer which has the second principal component in contact with the p-type semiconductor layer of the photoelectric conversion layer is an oxide of aluminum that holds the negative charges transparent intermediate layer, but is deposited on a substrate, wherein said intermediate layer first A photoelectric conversion device in which the main component in contact with the n-type semiconductor layer of one photoelectric conversion layer is any one of Si oxide, ZnO, and hafnium oxide that holds a positive charge .

If the p-type microcrystalline Si semiconductor layer 6a side is a layer 5b containing aluminum oxide as a main component, the n-type amorphous Si semiconductor layer 4c side is ZnO, a hafnium oxide compound (instead of the Si oxide layer 5a). Similar effects can be obtained by using a dielectric material such as HfO ₂ ). The intermediate layer 5 has two layers of the aluminum oxide compound layer 5b and the Si oxide layer 5a. However, the intermediate layer 5 may have a gradient composition structure in which the composition sequentially changes from the aluminum oxide compound to the Si oxide in the thickness direction. .

Claims (7)

a first photoelectric conversion layer having an n-type semiconductor layer and a p-type semiconductor layer;
a second photoelectric conversion layer having an n-type semiconductor layer and a p-type semiconductor layer and having a light absorption wavelength characteristic different from that of the first photoelectric conversion layer;
It is sandwiched between the n-type semiconductor layer of the first photoelectric conversion layer and the p-type semiconductor layer of the second photoelectric conversion layer, has tunnel conductivity, and is in contact with the p-type semiconductor layer of the second photoelectric conversion layer. A light-transmitting intermediate layer whose main component is aluminum oxide;
Is a photoelectric conversion device laminated on a substrate. 2. The photoelectric conversion device according to claim 1, wherein a main component of the intermediate layer in contact with the n-type semiconductor layer of the first photoelectric conversion layer is any one of Si oxide, ZnO, and hafnium oxide. a first photoelectric conversion layer having an n-type semiconductor layer and a p-type semiconductor layer;
a second photoelectric conversion layer having an n-type semiconductor layer and a p-type semiconductor layer and having a light absorption wavelength characteristic different from that of the first photoelectric conversion layer;
Between the n-type semiconductor layer of the first photoelectric conversion layer and the p-type semiconductor layer of the second photoelectric conversion layer and having tunnel conductivity, the n-type semiconductor layer of the first photoelectric conversion layer and the A translucent intermediate layer whose main component in contact with the p-type semiconductor layer of the second photoelectric conversion layer is hafnium oxide;
Is a photoelectric conversion device laminated on a substrate. The photoelectric conversion device according to claim 1 or 3, wherein the first photoelectric conversion layer and the second photoelectric conversion layer contain Si as a main component. The n-type semiconductor layer of the first photoelectric conversion layer includes a plurality of layers having different impurity concentrations, and the impurity concentration of a layer in contact with the intermediate layer among the plurality of layers is the highest. 3. The photoelectric conversion device according to 3. The p-type semiconductor layer of the second photoelectric conversion layer is composed of a plurality of layers having different impurity concentrations, and the impurity concentration of a layer in contact with the intermediate layer among the plurality of layers is the highest. 3. The photoelectric conversion device according to 3. a first photoelectric conversion layer having an n-type semiconductor layer and a p-type semiconductor layer;
a second photoelectric conversion layer having an n-type semiconductor layer and a p-type semiconductor layer and having a light absorption wavelength characteristic different from that of the first photoelectric conversion layer;
A light-transmitting intermediate layer made of a metal oxide material having tunnel conductivity sandwiched between an n-type semiconductor layer of the first photoelectric conversion layer and a p-type semiconductor layer of the second photoelectric conversion layer; ,
Are stacked on the substrate,
The intermediate layer metal oxide material is arranged so that the electron energy level of the n-type semiconductor layer of the first photoelectric conversion layer approaches the hole energy level of the p-type semiconductor layer of the second photoelectric conversion layer. The electron energy level in the vicinity of the interface between the n-type semiconductor layer of the first photoelectric conversion layer and the intermediate layer or the hole energy level in the vicinity of the interface between the p-type semiconductor layer of the second photoelectric conversion layer and the intermediate layer. A photoelectric conversion device which is a material to be changed.

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