JP2011198848A - Photoelectric converter and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric converter capable of improving conductivity between two photoelectric conversion layers across an intermediate layer, and a method of manufacturing the photoelectric converter.SOLUTION: The photoelectric converter includes: a first photoelectric conversion layer having an n-type semiconductor layer and a p-type semiconductor layer; a second photoelectric conversion layer with light absorption wavelength characteristics differing from those of the first photoelectric conversion layer and having an n-type semiconductor layer and a p-type semiconductor layer; and the intermediate layer interposed between the n-type semiconductor layer of the first photoelectric conversion layer and the p-type semiconductor layer of the second photoelectric conversion layer. The intermediate layer has an electrical double layer where molecules are oriented so that a region of positive charge in the molecule is directed toward the n-type semiconductor layer in the first photoelectric conversion layer and a region of negative charge in the molecule is directed toward the p-type semiconductor layer in the second photoelectric conversion layer.

Description

  The present invention relates to a photoelectric conversion device and a method for manufacturing the photoelectric conversion device.

  As a photoelectric conversion device that converts light energy into electrical 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 laminated thin film solar cell, a photoelectric conversion layer in which a p-type layer, an i-type layer, and an n-type layer, which are thin film semiconductors, are sequentially deposited on an insulating transparent substrate on which a transparent electrode is formed. A plurality of layers are stacked, and a reflective conductive film is formed thereon as a back electrode. This laminated thin-film solar cell generates a photovoltaic force by light incident on a plurality of photoelectric conversion layers from the insulating transparent substrate side.

  Patent Document 1 describes a configuration in which a transparent intermediate layer is arranged between an amorphous silicon solar cell (top cell) and a crystalline silicon solar cell (bottom cell) in a thin film silicon laminated solar cell. Yes. The transparent intermediate layer reflects sunlight in a spectral region used for power generation in the amorphous silicon solar cell (top cell) and re-enters the amorphous silicon solar cell (top cell). Thereby, according to patent document 1, it is supposed that the power generation efficiency in an amorphous silicon solar cell (top cell) can be improved.

  Patent Document 2 describes that in a tandem photoelectric conversion element, a connection layer that connects a front cell and a back cell is formed of an organic compound that has an electron transporting property and is coordinated with a cyano group (CN). ing. Thus, according to Patent Document 2, since a function of generating holes in the connection layer can be provided, it is possible to perform bonding with a small barrier between the front cell and the back cell.

JP 2006-120747 A JP 2008-117798 A

Patent Document 1 discloses that ZnO, ITO, or SnO ₂ is used as a material for the transparent intermediate layer. This transparent intermediate layer is sandwiched between an n-type silicon layer in an amorphous silicon solar cell (top cell) and a p-type silicon layer in a crystalline silicon solar cell (bottom cell).

  The transparent intermediate layer described in Patent Document 1 is considered to be an n-type semiconductor in order to achieve both translucency and carrier conductivity. When the transparent intermediate layer is an n-type semiconductor, even if the contact resistance with the n-type silicon layer can be lowered, the contact resistance with the p-type silicon layer on the opposite side becomes a pn reverse junction, thus reducing the contact resistance. Is difficult. Thereby, the electrical conductivity between the amorphous silicon solar cell and the crystalline silicon solar cell (two photoelectric conversion layers) arranged with the transparent intermediate layer interposed therebetween is lowered. In particular, when the current generated by an amorphous silicon solar cell or a crystalline silicon solar cell is high, the current flowing is limited by the resistance of the portion that becomes the pn reverse junction, and the thin film silicon laminated solar cell (photoelectric conversion) The light conversion efficiency of the device is significantly reduced.

  In the technique of Patent Document 2, the connection layer is sandwiched between the hole block layer (n-type organic semiconductor) in the front cell and the hole transport layer (p-type organic semiconductor) in the back cell. In addition, since the connection layer has an electron transport material as a basic skeleton, it has high affinity with an n-type organic semiconductor in contact with the connection layer. However, Patent Document 2 does not describe the affinity with the p-type organic semiconductor in contact with the connection layer. Patent Document 2 does not describe the orientation of each molecule in the connection layer.

  This invention is made | formed in view of the above, Comprising: It aims at obtaining the manufacturing method of the photoelectric conversion apparatus which can improve the electroconductivity between the two photoelectric conversion layers which pinch | interpose an intermediate | middle layer, and a photoelectric conversion apparatus. .

  In order to solve the above-described problems and achieve the object, a photoelectric conversion device according to one aspect of the present invention includes a first photoelectric conversion layer having an n-type semiconductor layer and a p-type semiconductor layer, and the first photoelectric conversion layer. The conversion layer and the light absorption wavelength characteristic are different, the second photoelectric conversion layer having an n-type semiconductor layer and a p-type semiconductor layer, the n-type semiconductor layer in the first photoelectric conversion layer, and the second photoelectric conversion layer an intermediate layer sandwiched between p-type semiconductor layers, the intermediate layer having an electric double layer, and a positive charge site in the molecule facing the n-type semiconductor layer side in the first photoelectric conversion layer The molecule is oriented so that the negatively charged portion in the molecule faces the p-type semiconductor layer side of the second photoelectric conversion layer.

  According to the present invention, the electron energy level of the n-type semiconductor layer in the first photoelectric conversion layer and the hole energy level of the p-type semiconductor layer in the second photoelectric conversion layer approach each other in the vicinity of the intermediate layer. Between the p-type semiconductor layer and the n-type semiconductor layer in the first photoelectric conversion layer becomes easier to flow through the intermediate layer. That is, the conductivity between the two photoelectric conversion layers sandwiching the intermediate layer can be improved.

1 is a cross-sectional view illustrating a schematic configuration of a photoelectric conversion apparatus according to Embodiment 1. FIG. FIG. 2 is a schematic diagram showing a state in the middle of forming the intermediate layer in the first embodiment. FIG. 3 is a diagram showing energy bands of the intermediate layer and the semiconductor layers bonded to both sides thereof in the first embodiment. FIG. 4 is a diagram showing energy bands of the intermediate layer and the semiconductor layers bonded to both sides thereof in the comparative example.

  Embodiments of a photoelectric conversion device according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
A schematic configuration of the photoelectric conversion device according to Embodiment 1 will be described with reference to FIG. 1 is a cross-sectional view illustrating a schematic configuration of a photoelectric conversion apparatus according to Embodiment 1. FIG.

  In the photoelectric conversion device 1, a transparent electrode 3, a photoelectric conversion layer (first photoelectric conversion layer) 4, an intermediate layer 5, a photoelectric conversion layer (second photoelectric conversion layer) 6, and a back electrode 7 are sequentially stacked on a substrate 2. Has been. An undercoat layer 8 such as Si oxide may be provided on the substrate 2, that is, between the substrate 2 and the transparent electrode 3, as an impurity blocking layer, if necessary.

  The board | substrate 2 is formed with the transparent substance (for example, glass) which has insulation. The transparent electrode 3 is disposed on the substrate 2. The transparent electrode 3 has a surface texture structure that is fine irregularities on its surface.

  The photoelectric conversion layer 4 and the photoelectric conversion layer 6 are both mainly composed of Si, but have different crystal structures. The photoelectric conversion layer 4 is made of, for example, amorphous Si. The photoelectric conversion layer 6 is made of, for example, microcrystalline Si. The photoelectric conversion layer 4 and the photoelectric conversion layer 6 have different band gaps due to differences in their crystal structures, and thus have different light absorption wavelength characteristics. The photoelectric conversion layer 4 absorbs light in the first wavelength region out of the received light, and generates (generates electric power) electric charges corresponding to the light in the first wavelength region. The photoelectric conversion layer 6 absorbs light in the second wavelength region out of the received light, and generates (generates electric power) electric charges corresponding to the light in the second wavelength region.

  The photoelectric conversion device 1 according to Embodiment 1 is a device that converts light incident mainly from the substrate 2 side into electricity using a transparent substrate 2. That is, the photoelectric conversion layer 4 and the intermediate layer 5 are arranged on the light incident side with respect to the photoelectric conversion layer 6. The power generation element of the photoelectric conversion layer 4 and the power generation element of the photoelectric conversion layer 6 are connected in series in the stacking direction, and the current (charge) generated in each photoelectric conversion layer is taken out from the transparent electrode 3 and the back electrode 7. It is a configuration. Such a photoelectric conversion device can be used as a tandem solar cell.

  In a tandem solar cell, a photoelectric conversion layer having a large band gap that mainly absorbs light of a short wavelength and converts it into electric energy is disposed on the light incident side, and is disposed on the back side (on the opposite side to the light incident side). A photoelectric conversion layer having a small band gap that absorbs light having a longer wavelength than the former and converts it into electrical energy is disposed.

  In the photoelectric conversion layer 4, a p-type semiconductor layer 4a, an i-type semiconductor layer 4b, an n-type semiconductor layer 4c, and an n-type semiconductor layer 4d are stacked in this order from the substrate 2 side. The p-type semiconductor layer 4a is formed of a semiconductor (for example, amorphous SiC) containing a p-type impurity such as boron. The i-type semiconductor layer 4b is formed of an intrinsic semiconductor (for example, amorphous Si). The n-type semiconductor layers 4c and 4d are formed of a semiconductor (for example, amorphous Si) containing an n-type impurity such as phosphorus or arsenic. Note that an i-type semiconductor layer (eg, formed of amorphous SiC) may be further inserted between the p-type semiconductor layer 4a and the i-type semiconductor layer 4b.

  In the photoelectric conversion layer 6, a p-type semiconductor layer 6d, a p-type semiconductor layer 6a, an i-type semiconductor layer 6b, and an n-type semiconductor layer 6c are stacked in this order from the substrate 2 side. The p-type semiconductor layers 6d and 6a are formed of a semiconductor (for example, microcrystalline Si) containing a p-type impurity such as boron. The i-type semiconductor layer 6b is formed of an intrinsic semiconductor (for example, microcrystalline Si). The n-type semiconductor layer 6c is formed of a semiconductor (for example, microcrystalline Si) containing an n-type impurity such as phosphorus or arsenic.

  The back electrode 7 can be formed of a metal having a high reflectance such as Al or an Al alloy, for example. Ag may be used instead of Al. When the back electrode 7 is formed of a material having excellent reflection performance, light transmitted through the photoelectric conversion layer 6 is reflected again by the back electrode 7 toward the photoelectric conversion layer 6 and is photoelectrically converted by the photoelectric conversion layer 6. Conversion efficiency is improved. In order to effectively reflect light in the wavelength region (second wavelength region) to be photoelectrically converted, a transparent conductive layer 11 such as ZnO having appropriate optical characteristics between the back electrode 7 and the n-type semiconductor layer 6c. May be inserted.

  The intermediate layer 5 is a layer sandwiched between the photoelectric conversion layer 4 and the photoelectric conversion layer 6. That is, the intermediate layer 5 is sandwiched between the n-type semiconductor layer 4 d in the photoelectric conversion layer (first photoelectric conversion layer) 4 and the p-type semiconductor layer 6 d in the photoelectric conversion layer (second photoelectric conversion layer) 6. The intermediate layer 5 transmits light that has not been absorbed by the photoelectric conversion layer 4 (light other than the first wavelength region in the received light) to the photoelectric conversion layer 6 side, and at the same time, the intermediate layer 5 includes the photoelectric conversion layer 4. And the photoelectric conversion layer 6 are electrically connected.

  The intermediate layer 5 transmits light in the wavelength region (second wavelength region) absorbed by the photoelectric conversion layer 6, while the light in the wavelength region (first wavelength region) absorbed by the photoelectric conversion layer 4 is converted to the photoelectric conversion layer 4. When the optical characteristic which reflects to the side is provided, the light which passed the photoelectric converting layer 4 will inject into the photoelectric converting layer 4 again, and will be photoelectrically converted, and conversion efficiency will improve. That is, the intermediate layer 5 has a light-transmitting property at least in the light wavelength region (second wavelength region) absorbed by the photoelectric conversion layer (second photoelectric conversion layer) 6 and is absorbed by the photoelectric conversion layer 4. Reflective performance in (first wavelength region).

  Since the intermediate layer 5 must transmit carriers (charges and currents) between the two photoelectric conversion layers (photoelectric conversion layer 4 and photoelectric conversion layer 6) sandwiching the layer without delay, carrier conductivity (conductivity) It is essential to have When carrier conduction is hindered between the two photoelectric conversion layers (the photoelectric conversion layer 4 and the photoelectric conversion layer 6), the effective connection resistance between the photoelectric conversion layers is increased, and the fill factor (FF) of the solar cell is increased. As a result, the power generation efficiency (photoelectric conversion efficiency) decreases. Therefore, the intermediate layer 5 must satisfy both the translucency in the predetermined wavelength region (second wavelength region) and the carrier conductivity between the two photoelectric conversion layers (the photoelectric conversion layer 4 and the photoelectric conversion layer 6). .

  In the first embodiment, the structure of the intermediate layer 5 is an electric double layer made of molecules having an electric dipole. That is, the intermediate layer 5 is formed of molecules having an electric dipole. The intermediate layer 5 has a positive charge site in the molecule facing the n-type semiconductor layer 4d side in the photoelectric conversion layer (first photoelectric conversion layer) 4 and a negative charge site in the molecule is the photoelectric conversion layer (second photoelectric layer). The molecules are oriented so as to face the p-type semiconductor layer 6d side in the conversion layer 6). Further, the intermediate layer 5 has translucency.

  Next, a method for manufacturing the photoelectric conversion device 1 according to Embodiment 1 will be described with reference to FIGS. FIG. 2 is a schematic diagram showing a state in the middle of forming the intermediate layer in the first embodiment.

  In the first step, the (undercoat layer 8) transparent electrode 3, p-type semiconductor layer 4 a, i-type semiconductor layer 4 b, n-type semiconductor layer 4 c, and n-type semiconductor layer 4 d are sequentially formed on the substrate 2. To do. Thereby, the photoelectric conversion layer (first photoelectric conversion layer) 4 including the n-type semiconductor layer 4c and the p-type semiconductor layer 4a is formed.

In the second step, the position to be sandwiched between the n-type semiconductor layer 4d in the photoelectric conversion layer (first photoelectric conversion layer) 4 and the p-type semiconductor layer 6d in the photoelectric conversion layer (second photoelectric conversion layer) 6, that is, photoelectric An intermediate layer 5 having an electric double layer is formed on the conversion layer (first photoelectric conversion layer) 4. The intermediate layer 5 is made of, for example, trifluoride alkylsilane (FAS3 [3,3,3-trifluoropropyl-trimethylsilane, CF ₃ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ ]) by self-contact in a gas phase. It was organized and formed as a monolayer. The intermediate layer 5 can also be formed by a dipping method in a solution or a vacuum deposition method.

  Here, the photoelectric conversion layer 4 is formed of, for example, amorphous Si in the order of p-i-n so that light incident on the substrate 2 through the transparent electrode 3 enters from the p-type semiconductor layer 4a side. Yes. For this reason, the intermediate layer 5 is formed on the n-type semiconductor layer 4 d in the photoelectric conversion layer 4. The intermediate layer 5 is formed on the surface of the sample taken out of the film forming apparatus after forming the n-type semiconductor layer 4d with, for example, amorphous Si (the surface of the n-type semiconductor layer 4d). The container containing the sample and the sample were sealed in a sealed container, and the entire sample was heated to about 150 ° C. and held for 3 hours to form a fluoroalkylsilane film as the intermediate layer 5 by self-assembly. As shown in FIG. 2, the formation by self-organization means that the silane portion (positively charged portion) has a fluorine portion (negatively charged portion) on the n-type semiconductor layer 4d side (formed with amorphous Si, for example). This means that a monomolecular layer is formed by orienting the portion to the outside (the side opposite to the n-type semiconductor layer 4d side). In other words, the directions of the electric dipole moment 402 by the electric dipole are aligned. That is, as shown in FIG. 2, the intermediate layer 5 is formed of a monomolecular layer in which a plurality of molecules 401 aligned in the direction of electric dipoles (electric dipole moment 402) are two-dimensionally arranged.

  Thus, due to the reactivity of the fluorinated alkylsilane and Si (n-type semiconductor layer 4d), the silane portion is on the Si side (n-type semiconductor layer 4d side) and the fluorine portion is on the surface side (p-type semiconductor to be formed). Oriented to the layer 6d side). As a result, an electric double layer is formed in which the substrate side (n-type semiconductor layer 4d side) is a positively charged layer and the surface side (p-type semiconductor layer 6d side to be formed) is a negatively charged layer.

As the fluorinated alkylsilane, for example, FAS3 [3,3,3-trifluoropropyloxysilane, CF ₃ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ ] containing 3 atoms of fluorine in one molecule is most preferable. Even molecules with a large molecular weight containing a large amount of fluorine are possible. However, in this case, since the film thickness is increased and the conductivity of the intermediate layer is impaired, it is preferable to keep the thickness at about 1 nm. The fluorine at this time is about 15 atoms and is FAS15 [CF ₃ (CH ₂ ) ₂ Si (OCH ₃ ) ₃ ]. That is, in the intermediate layer 5, the photoelectric conversion layer 4 is disposed on the light incident side with respect to the intermediate layer 5, the p-type semiconductor layer 4a is disposed on the light incident side in the photoelectric conversion layer 4, and the n-type semiconductor layers 4c and 4d are formed. When arranged on the side opposite to the light incident side, a group of substances consisting of (3 + 2n) fluoroalkylsilane [CF ₃ (CH ₂ ) ₂ (CF ₂ ) _n Si (OCH ₃ ) ₃ ; n = 0 to 6] It may be formed of a substance selected from

  In the third step, a p-type semiconductor layer 6d, a p-type semiconductor layer 6a, an i-type semiconductor layer 6b, and an n-type semiconductor layer 6c are sequentially formed on the intermediate layer 5. Thereby, the photoelectric conversion layer (second photoelectric conversion layer) 6 including the n-type semiconductor layer 6c and the p-type semiconductor layers 6d and 6a is formed.

  Then, a back electrode 7 (transparent conductive layer 11) is formed on the photoelectric conversion layer 6 in order. Thereby, the photoelectric conversion apparatus 1 shown in FIG. 1 is obtained.

  Next, how the conductivity between the two photoelectric conversion layers (the photoelectric conversion layer 4 and the photoelectric conversion layer 6) is improved by the intermediate layer 5 in Embodiment 1 will be described with reference to FIG. . FIG. 3 is a diagram showing energy bands of the intermediate layer and the semiconductor layers bonded to both sides thereof in the first embodiment.

  3 shows an intermediate layer 306 (an intermediate layer shown in FIG. 1) between an n-type semiconductor layer 302 (an n-type semiconductor layer 4d shown in FIG. 1) and a p-type semiconductor layer 303 (a p-type semiconductor layer 6d shown in FIG. 1). Layer 5) is sandwiched. In the intermediate layer (molecular film composed of an electric double layer) 306, there is a state where the negative charge holding portion 304 is located on the n-type semiconductor layer 302 side and the positive charge holding portion 305 is located on the p-type semiconductor layer 303 side. It is shown in the figure. The dotted line in FIG. 3 indicates the Fermi level Ef.

Here, suppose that the intermediate layer 1301 is formed of ZnO, ITO, or SnO ₂ as shown in FIG. In this case, the intermediate layer 1307 itself is an n-type semiconductor. Then, the conduction band energy (Ec, n), valence band energy (Ev, n) of the n-type semiconductor layer 1302 located on both sides of the intermediate layer 1307, the conduction band energy (Ec, p) of the p-type semiconductor layer 1303, The energy level of the valence band energy (Ev, p) does not change in the vicinity of the intermediate layer 1301. That is, in the vicinity of the intermediate layer 1301, the conduction band energy (Ec, n) of the n-type semiconductor layer 302 and the conduction band energy (Ec, p) of the p-type semiconductor layer 303 are at the same level. In the vicinity of the intermediate layer 1301, the valence band energy (Ev, n) of the n-type semiconductor layer 1302 and the valence band energy (Ev, p) of the p-type semiconductor layer 1303 are at the same level. Thereby, it is difficult to cause tunnel conduction between the p-type semiconductor layer 1303 and the n-type semiconductor layer 1302.

  In contrast, in the first embodiment, as shown in FIG. 3, in the intermediate layer 306 (intermediate layer 5 shown in FIG. 1), on the n-type semiconductor layer 302 (n-type semiconductor layer 4d shown in FIG. 1) side. The negative charge holding portion 304 (negative charge layer) is disposed on the positive charge holding portion 305 (positive charge layer) and the p-type semiconductor layer 303 (p-type semiconductor layer 6d shown in FIG. 1). Thereby, in the vicinity of the intermediate layer 5, that is, in the vicinity of the interface between the positive charge holding unit 305 and the negative charge holding unit 304 due to the difference in accumulation tendency between holes (positive charge) and electrons (negative charge) of each layer. The slopes of the energy levels of the n-type semiconductor layer 302 and the p-type semiconductor layer 303 change. As a result, the conduction band energy (Ec, n) of the n-type semiconductor layer 302 and the valence band energy (Ev, p) of the p-type semiconductor layer 303 are close to each other.

  That is, the energy level of each of the n-type semiconductor layer 302 and the hole energy level of the n-type semiconductor layer 302 is changed in the vicinity of the interface between the positive charge holding unit 305 and the negative charge holding unit 304 so as to approach each other. Yes. Thus, when the energy gap between the n-type conduction band and the p-type 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, the electron energy level of the n-type semiconductor layer 302 and the hole energy level of the p-type semiconductor layer 303 approach each other in the vicinity of the intermediate layer 306, and the p-type semiconductor layer 6a and the n-type semiconductor are in contact with each other. It becomes easy for a tunnel current to flow between the layers 4c through the intermediate layer 5 (to facilitate charge tunneling). That is, the conductivity between the two photoelectric conversion layers 4 and 6 sandwiching the intermediate layer 5 can be improved. As a result, the photoelectric conversion efficiency of the photoelectric conversion device 1 is improved. Moreover, since the intermediate layer 5 can be formed as a monomolecular film by self-organization, the manufacturing cost of the photoelectric conversion device 1 can be reduced.

  Also, suppose that a fixed charge in the insulating film is used to control the potential. In this case, if the insulating film thickness is reduced to increase the tunnel current, the electric charge is reduced and the potential control effect is reduced. It is difficult to control the potential while maintaining conductivity.

  On the other hand, according to the first embodiment, the electric double layer of the positive charge holding unit 305 and the negative charge holding unit 304 is formed in the intermediate layer 5 to control the potential. The current can be increased.

  Note that, as the photoelectric conversion layer having different light absorption wavelength characteristics, materials having different crystallization ratios in the photoelectric conversion layer 4 and the photoelectric conversion layer 6 are used in Embodiment 1, but layers having different elemental compositions may be used. For example, the photoelectric conversion layer 4 and the photoelectric conversion layer 6 are adjusted such that the ratio of Ge or C added to the Si semiconductor layer is changed and the band gap is adjusted so that the light absorption wavelength characteristics are different between the stacked photoelectric conversion layers. May be. Further, in the photoelectric conversion device 1, three or more photoelectric conversion layers may be stacked. In that case, it is good also as a structure which has the intermediate | middle layer 5 distribute | arranged between each photoelectric converting layer, and two or more.

  Moreover, the order of lamination | stacking of each layer in the photoelectric conversion apparatus 1 is not limited above. That is, in the photoelectric conversion device 1, the order of stacking from the substrate 2 may be reversed, and light may be incident from the film surface side opposite to the substrate 2. When light is incident from the film surface side, the substrate 2 does not have to be transparent.

  For example, if the intermediate layer 5 is sandwiched between the n-type semiconductor layer 4d in the photoelectric conversion layer (first photoelectric conversion layer) 4 and the p-type semiconductor layer in the photoelectric conversion layer (second photoelectric conversion layer) 6, In the conversion device 1, the transparent electrode 3, the photoelectric conversion layer (second photoelectric conversion layer) 6, the intermediate layer 5, the photoelectric conversion layer (first photoelectric conversion layer) 4, and the back electrode 7 are sequentially stacked on the substrate 2. It may be. In this case, for example, in the photoelectric conversion layer 4, an n-type semiconductor layer 4d, an n-type semiconductor layer 4c, an i-type semiconductor layer 4b, and a p-type semiconductor layer 4a may be stacked in this order from the substrate 2 side. In the photoelectric conversion layer 6, an n-type semiconductor layer 6c, an i-type semiconductor layer 6b, a p-type semiconductor layer 6a, and a p-type semiconductor layer 6d may be stacked in this order from the substrate 2 side.

  In this case, in the first step, on the substrate 2, the (undercoat layer 8) transparent electrode 3, n-type semiconductor layer 6 c, i-type semiconductor layer 6 b, p-type semiconductor layer 6 a, p-type semiconductor layer 6d are formed in order. Thereby, the photoelectric conversion layer (second photoelectric conversion layer) 6 including the n-type semiconductor layer 6c and the p-type semiconductor layers 6d and 6a is formed. In the second step, the position to be sandwiched between the n-type semiconductor layer 4d in the photoelectric conversion layer (first photoelectric conversion layer) 4 and the p-type semiconductor layer 6d in the photoelectric conversion layer (second photoelectric conversion layer) 6, that is, photoelectric On the conversion layer (second photoelectric conversion layer) 6, the intermediate layer 5 is formed of molecules having an electric dipole. In the third step, an n-type semiconductor layer 6c, an i-type semiconductor layer 6b, a p-type semiconductor layer 6a, and a p-type semiconductor layer 6d are sequentially formed on the intermediate layer 5. Thereby, the photoelectric conversion layer (second photoelectric conversion layer) 6 including the n-type semiconductor layer 6c and the p-type semiconductor layers 6d and 6a is formed. Thereby, the intermediate layer 5 sandwiched between the n-type semiconductor layer 4d in the photoelectric conversion layer (first photoelectric conversion layer) 4 and the p-type semiconductor layer in the photoelectric conversion layer (second photoelectric conversion layer) 6 is obtained.

Embodiment 2. FIG.
A photoelectric conversion device 1 according to Embodiment 2 will be described. Below, it demonstrates focusing on a different point from Embodiment 1. FIG.

  In the photoelectric conversion device 1 according to Embodiment 2, the intermediate layer 5 is formed of a material selected from a group of materials made of para-substituted benzene chloride derivatives. That is, in the second step, the intermediate layer 5 was formed as a monomolecular film by being self-assembled by immersing it in dichloromethane containing 1 mmol of p-substituted chlorophenylphosphoryl dichloride for 5 minutes, for example. Further, this was dried at 150 ° C. in a nitrogen gas atmosphere.

  The monomolecular film thus formed has a COCl group (positively charged portion) facing the n-type semiconductor layer 4d side and a Cl group (negatively charged portion) facing the p-type semiconductor layer 6d side. The molecules are oriented. As a result, an electric double layer is formed in which the substrate side (n-type semiconductor layer 4d side) is a positively charged layer and the surface side (p-type semiconductor layer 6d side to be formed) is a negatively charged layer.

  Therefore, also in the second embodiment, in the vicinity of the intermediate layer 306, the electron energy level of the n-type semiconductor layer 302 (n-type semiconductor layer 4d) and the hole energy level of the p-type semiconductor layer 303 (p-type semiconductor layer 6d) And the tunnel current easily flows between the p-type semiconductor layer 6a and the n-type semiconductor layer 4c through the intermediate layer 5 (it becomes easier to conduct charge tunneling).

  The configuration of the above embodiment is particularly suitable for improving the conversion efficiency of a photoelectric conversion layer composed of a semiconductor layer containing Si as a main component, but it can also be applied to compounds such as compound semiconductors other than Si and organic materials. .

  As described above, the photoelectric conversion device and the method for manufacturing the photoelectric conversion device according to the present invention are useful for stacked thin-film solar cells.

1 Photoelectric conversion device 2 Substrate
3 transparent electrode 4 photoelectric conversion layer 4a p-type semiconductor layer 4b i-type semiconductor layer 4c, 4d n-type semiconductor layer 5 intermediate layer 6 photoelectric conversion layer 6a, 6d p-type semiconductor layer 6b i-type semiconductor layer 6c n-type semiconductor layer 7 back surface Electrode 8 Undercoat layer 11 Transparent conductive layer 302 n-type semiconductor layer 303 p-type semiconductor layer 304 Negative charge holding portion 305 Positive charge holding portion 306 Intermediate layer 401 Molecule 402 Electric dipole moment 1302 n-type semiconductor layer 1303 p-type semiconductor layer 1307 Middle class

Claims (6)

a first photoelectric conversion layer having an n-type semiconductor layer and a p-type semiconductor layer;
A light absorption wavelength characteristic different from that of the first photoelectric conversion layer, a second photoelectric conversion layer having an n-type semiconductor layer and a p-type semiconductor layer;
An intermediate layer sandwiched between an n-type semiconductor layer in the first photoelectric conversion layer and a p-type semiconductor layer in the second photoelectric conversion layer;
With
The intermediate layer has an electric double layer, a positive charge site in the molecule is directed toward the n-type semiconductor layer in the first photoelectric conversion layer, and a negative charge site in the molecule is the second photoelectric conversion. The photoelectric conversion device, wherein the molecules are oriented so as to face the p-type semiconductor layer side of the layer. The first photoelectric conversion layer and the intermediate layer are arranged on the light incident side with respect to the second photoelectric conversion layer,
The photoelectric conversion device according to claim 1, wherein the intermediate layer has translucency at least in a light wavelength region absorbed by the second photoelectric conversion layer. The photoelectric conversion device according to claim 1, wherein the intermediate layer is formed of a monomolecular layer in which a plurality of molecules aligned in the direction of electric dipoles are arranged two-dimensionally. In the intermediate layer, the first photoelectric conversion layer is disposed on a light incident side with respect to the intermediate layer, a p-type semiconductor layer is disposed on a light incident side in the first photoelectric conversion layer, and an n-type semiconductor layer is light incident. Selected from a group of substances consisting of (3 + 2n) fluorinated alkylsilanes [CF ₃ (CH ₂ ) ₂ (CF ₂ ) _n Si (OCH ₃ ) ₃ ; n = 0-6] The photoelectric conversion device according to any one of claims 1 to 3, wherein the photoelectric conversion device is formed of a formed material. The photoelectric conversion device according to any one of claims 1 to 3, wherein the intermediate layer is formed of a material selected from a group of materials made of a para-substituted benzene chloride derivative. forming a first photoelectric conversion layer having an n-type semiconductor layer and a p-type semiconductor layer;
Forming a second photoelectric conversion layer having a light absorption wavelength characteristic different from that of the first photoelectric conversion layer and having an n-type semiconductor layer and a p-type semiconductor layer;
Forming an intermediate layer having an electric double layer at a position to be sandwiched between an n-type semiconductor layer in the first photoelectric conversion layer and a p-type semiconductor layer in the second photoelectric conversion layer;
With
In the step of forming the intermediate layer, the positive charge portion in the molecule is directed to the n-type semiconductor layer side in the first photoelectric conversion layer, and the negative charge portion in the molecule is p in the second photoelectric conversion layer. Self-organization for orienting the molecules so as to face the type semiconductor layer side. A method for manufacturing a photoelectric conversion device, comprising:

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