JP2004356626A - Polymer thin film having interlaminated structure, and photoelectric element and solar cell using the film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molecular system using an organic polymer thin-film, which performs a series of processes of photoabsorption, electron transport (electron reception), and hole transport (electron donating) without requiring complicated synthesis or operation. <P>SOLUTION: The polymer thin film comprises a multilayer thin-film having at least one set of alternative absorption-films of a cation polymer and/or an anion polymer introduced at least partially with a photosensitization group, and has gradient in the highest occupied electronic level or the lowest unoccupied electronic level of each layer of the multilayer thin-film including the alternative absorption-films. A photoelectric element and a solar cell are prepared using the thin film. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a polymer thin film having an alternately laminated structure, a photoelectric device using the same, and a solar cell, and more particularly to a polymer thin film having a photoelectric conversion function.

  Generally, methods for forming a thin film on a substrate are roughly classified into two types: a dry method and a wet method. As the former method, methods such as vacuum deposition, sputtering, and molecular beam epitaxy are known as typical methods. These film forming methods are excellent in controllability of the film thickness, but are unsuitable for thinning the organic material because they require high temperature and high vacuum. Further, there is a problem that it is difficult to form a film over a large area, and the production cost rises. On the other hand, as the latter method, a solution casting method, a spin coating method, a Langmuir-Blodgett method and the like are known as typical methods. All of these processes are performed at normal temperature and normal pressure, but the solution casting method and the spin coating method have a problem that the controllability of the film thickness is lacking. In addition, it is difficult to increase the area by the spin coating method. The Langmuir-Blodgett method is excellent in controllability of the film thickness, but has another problem that the material that can be handled is limited and the strength of the thin film is lacking. As described above, each of the existing film forming methods has advantages and disadvantages, and the film forming method is appropriately used in consideration of the use and cost of the film.

  In recent years, a solution containing positive charged particles and a solution containing negative charged particles are prepared, and the substrate is alternately immersed in these solutions to form a layer based on the positive charged particles and a negative charged particle on the substrate surface. In the early 1990s, an alternate adsorption method (Layer-by-Layer Electrostatic Self-Assembly Process) for alternately forming layers based on the method was proposed. The alternate adsorption method is a film formation method belonging to the category of a wet method in which a substrate is immersed in a water tank, and is suitable for thinning an organic material as compared with a dry method because a high temperature is not used. Further, vacuum equipment required by the dry method is not required. Therefore, even when a large-area film is manufactured, relatively low-cost equipment is sufficient.

  In 1992, Decher et al. Invented an alternate adsorption method utilizing electrostatic attraction. This alternate adsorption method is a method that focuses on using alternate adsorption (Layer-by-Layer Electrostatic Self-Assembly) to produce a composite organic thin film. Since (Non-Patent Document 1 below), it has become known that not only synthetic polymers but also various materials such as biological materials, inorganic substances, and metal particles become laminated thin films.

Subsequently, electron transfer and energy transfer between the layers of the polymer electrolyte carrying the dye have been reported (Non-Patent Document 2 below), and redox due to electron transfer of the fullerene laminated film on the ITO electrode has been reported ( The following non-patent document 3). The present inventors have also reported the redox behavior of a ruthenium complex or a ferrocene group laminated on an electrode. Therefore, it is a known technique to produce a laminate in which a photo- or electronic functional group is introduced as a single component in a polymer laminated film or a laminate having two different functional groups in the polymer laminated film using the alternate adsorption method.
The details of the method for producing such an alternate adsorption film are disclosed in, for example, Patent Document 1 below.

  On the other hand, in order to realize a highly efficient photoelectric conversion film in an organic system, it is necessary to create a molecular system that performs a series of processes of light absorption, photoinduced electron transfer, charge separation, and charge transport. For this reason, a molecular system having a nanometer-scale arrangement has been proposed using the SAM method (Self Assembled Monolayer) or the LB method. However, the SAM method and LB method require too complicated synthesis or operation to arrange the various functional groups responsible for each process at the nanoscale according to their functions, so that a system that can be put to practical use is realized. It was difficult to do.

International Publication WO00 / 13806 Decher.G, Hong.J.D.J.Schmit: Thin Solid Films, 210/211, p.831 (1992) Mallouk: J. Am. Chem. Soc., 121, 3435 (1999) Han, Langmuir, 16, 6777 (2000) P. Bertrand, A. Jonas, A. Laschewsky, R. Legras, Macromol. Rapid Commun., 21, 319-348 (2000) Kazuyuki Horie, Akio Taniguchi, Handbook of Organic Materials for Optical and Electronic Functions, Asakura Publishing (1995)

In order to promote the use of the multilayered organic polymer thin film as a useful photoelectric device, each layer of light absorption, electron transport (electron acceptance), and hole transport (electron donation) having an internal potential gradient is complicated. The challenge is to establish a series of processes that can be formed without the need for synthesis or manipulation.
In addition, when the photoelectric element is formed by the above-described conventional thin film forming method, the dye or the electronic functional group constituting each of the above-described layers aggregates or crystallizes, thereby causing a change in potential, causing excitons, holes, There is a problem that the transfer characteristics of electrons and the like deteriorate.

  Furthermore, in recent years, as conditions for performing photoelectric conversion of a photoelectric element with high efficiency, the inventors have to set the optimum thickness of the light absorption layer constituting the photoelectric element in an extremely thin range of 1 nm to 30 nm. I found that. Furthermore, the inventors have come to the opinion that since the photoelectric conversion characteristics fluctuate sensitively to the diffusion length of excitons, the thickness of the light absorbing layer should be formed with precise control.

However, in the conventional methods such as the vacuum evaporation method, the solution casting method, and the spin coating method, the light absorption layer disposed between the hole transport layer and the electron transport layer has a thickness within the above range. It could not be formed with high dimensional accuracy and stably fixed. That is, when the light absorbing layer is formed by the above-described conventional method, there is a problem that each functional group of the light absorbing layer diffuses into the adjacent layers (hole transport layer and electron transport layer) due to heating or passage of time. .
As described above, since the photoelectric element formed by the conventional thin film forming method cannot obtain a constant film thickness, there is a large variation in photoelectric conversion characteristics, and furthermore, there is a problem of durability that easily deteriorates with time. I was

  The present inventors have conducted intensive studies, and as a result, accumulated three or more types of functional base layers including electrodes over two or more multilayers on an electrode substrate such as ITO or a metal thin film using an alternate adsorption method, and obtained a potential. The inventors have found that a useful device can be produced by forming a gradient on these electrodes or in a thin film, and systematically and efficiently performing desired electron transfer, charge separation and subsequent charge transport, and arrived at the present invention. .

  That is, first, the present invention is an invention of a polymer thin film, and comprises a multilayer thin film having at least one layer of an alternately adsorbed film of a cationic polymer and / or an anionic polymer having a photosensitizing group introduced into at least a part thereof. In addition, the highest occupied molecular orbital level or the lowest unoccupied molecular orbital level of each layer of the multilayer thin film including the alternating adsorption film has a gradient.

  Second, the present invention is an invention of a photoelectric device, the first structure of which includes a first electrode layer, a hole transporting (electron donating) layer, a light absorbing layer, an electron transporting (electron accepting) layer, and a 2. A photoelectric device comprising the two electrode layers, wherein the hole transport layer is formed of a cationic polymer and an anionic polymer into which an electron donating group is introduced, or an anionic polymer and a cationic polymer into which an electron donating group is introduced. An alternating adsorption film, wherein the alternate adsorption film has a multilayer structure comprising at least one pair of the cationic polymer layer and the anionic polymer layer, and the first electrode layer, the hole transport (electron donating) layer, And the highest occupied electron level of the light absorbing layer is improved as approaching the first electrode layer.

  The second structure of the photoelectric device of the present invention is a photoelectric device comprising a first electrode layer, a hole transporting (electron donating) layer, a light absorbing layer, an electron transporting (electron accepting) layer, and a second electrode layer. The electron transport layer comprises an alternately adsorbed film of a cationic polymer and an anionic polymer into which an electron accepting group is introduced, or an anionic polymer and a cationic polymer into which an electron accepting group is introduced. Has a multilayer structure comprising at least one set of the cationic polymer and the anionic polymer, and the light absorbing layer, the electron transporting (electron accepting) layer, and the second electrode layer have a minimum vacancy level of It is characterized in that it decreases as it approaches the second electrode layer.

A third structure of the photoelectric device of the present invention is a photoelectric device including a first electrode layer, a hole transport (electron donating) layer, a light absorbing layer, an electron transport (electron accepting) layer, and a second electrode layer. The hole transport layer is composed of an alternately adsorbed film of a cationic polymer and an anionic polymer having an electron donating group introduced therein, or an anionic polymer and a cationic polymer having an electron donating group introduced therein, and the electron transporting layer. The transport layer comprises an alternately adsorbed film of a cationic polymer and an anionic polymer having an electron-accepting group introduced therein, or an anionic polymer and a cationic polymer having an electron-accepting group introduced therein. Is a multilayer structure composed of at least one set of the cationic polymer and the anionic polymer, and the first electrode layer, the hole transport (electron donating) layer, and the light absorption layer. The highest occupied electron in the layer And the lowest vacancy level of the light absorbing layer, the electron transporting (electron accepting) layer, and the second electrode layer is closer to the second electrode layer. Characterized by the following:

  A fourth structure of the photoelectric device of the present invention is a photoelectric device comprising a first electrode layer, a light absorbing layer, an electron transport (electron accepting) layer, and a second electrode layer, wherein the electron transport layer is an electron transport layer. An alternately adsorbing film of a cationic polymer and an anionic polymer into which an accepting group is introduced, or an anionic polymer and a cationic polymer into which an electron accepting group is introduced, wherein the alternately adsorbing film comprises at least one set of the cationic polymer And the above-described anionic polymer, and the lowest vacancy level of the light absorbing layer, the electron transporting (electron accepting) layer, and the second electrode layer decreases as approaching the second electrode layer. It is characterized by doing.

  A fifth structure of the photoelectric device according to the present invention is a photoelectric device comprising a first electrode layer, a hole transport (electron donating) layer, a light absorbing layer, and a second electrode layer, wherein the hole transport layer Comprises an alternately adsorbed film of a cationic polymer and an anionic polymer into which an electron donating group is introduced, or an anionic polymer and an anionic polymer into which an electron donating group is introduced, wherein the alternately adsorbed film has at least one layer of the cation. The first electrode layer, the hole transport (electron donating) layer, and the highest occupied electron level of the light absorption layer are a multilayer structure composed of a polymer and the anion polymer. It is characterized in that it is improved as it approaches.

  Here, in the photoelectric device having the second to fifth structures, the light absorbing layer may be made of a cationic polymer and an anionic polymer having a photosensitizing group introduced, or an anionic polymer and a cationic polymer having a photosensitizing group introduced therein. The alternate adsorption film may have a multilayer structure composed of at least one set of the cationic polymer and the anionic polymer.

In the photoelectric device of the present invention, the first electrode layer can also serve as a hole transport layer. Further, the second electrode layer can also serve as the electron transport layer.
In the photoelectric device of the present invention, a ruthenium complex-based compound having a high extinction coefficient and excellent light resistance as a photosensitizing group is preferably exemplified. Preferred examples of the electron donating group include thiophene compounds and ferrocene compounds. Further, a fullerene derivative is preferably exemplified as the electron accepting group.

  Third, the present invention is a solar cell invention, which is configured using the photoelectric element of the second invention and has a function of converting sunlight into electric power.

ADVANTAGE OF THE INVENTION According to this invention, the multilayer thin film which consists of a multilayer thin film which has at least one layer of the alternating adsorption film of the cationic polymer and / or the anionic polymer which introduce | transduced the photosensitizing group in at least one part, and contains this alternate adsorption film By using a polymer thin film with a gradient in the highest occupied molecular orbital level or the lowest unoccupied molecular orbital level in each layer, light absorption and electron transport (electron acceptance) can be performed without complicated synthesis or manipulation. A molecular system that performs a series of hole transport (electron donation) processes can be constructed.
Furthermore, if each layer (a hole transport layer, a light absorption layer, an electron transport layer, etc.) of the multilayer thin film is formed by the alternate adsorption method, each of these layers can be configured as a thin film whose thickness is controlled on the order of nanometers. . This makes it possible to form a film by precisely controlling the thickness of each layer constituting the photoelectric element so that the photoelectric conversion efficiency is maximized, and to maximize the performance of the photoelectric element.
Further, each layer formed by the alternate adsorption method is fixed in a chemically physically stable state without interfering with an adjacent layer. This makes it possible to obtain a stable photoelectric element of low quality with little deterioration over time even after long-term use.

First, with reference to FIG. 12, the configuration of the photoelectric device of the present invention will be described by way of example. FIG. 12 is a conceptual diagram showing a type in which at least the light absorbing layer of the photoelectric device of the present invention is formed by the alternate adsorption method.
In the description of the photoelectric device according to the present invention, in particular, the case where the light absorption layer is formed by the alternate adsorption method is taken up, as described above, in the photoelectric conversion characteristics of the photoelectric device. This is because the control of the film thickness is particularly important for the performance of the photoelectric device.
Therefore, even if not described in the drawings, it should be understood that the case where any one layer except the light absorbing layer is formed by the alternate adsorption method is also included in the category to be protected in the present invention. is there.
In FIG. 12, in the case where reference numerals are appended with a suffix, for example, as indicated by reference numerals 50 ₁ and 50 ₂ , the individual elements shown in the drawings are respectively specified and indicated. when a description omitted subscripts, those containing omitted index (code 50 _1, 50 _2, 50 ₃ ...) and that the generically refers to.

In the drawings, a layer with a spiral pattern indicates a layer formed by an alternate adsorption method described later. That is, the hole transport layer P (P ₄ , P ₅ , P ₇ , P ₁₁ , P ₁₂ , P ₁₄ ) formed by the alternate adsorption method has an electron donating group (first electron donating group) introduced. A layer comprising an alternating adsorption film of a cationic polymer and an anionic polymer, or an anionic polymer having introduced an electron donating group and a cationic polymer, wherein the alternating adsorption film comprises at least one pair of the cationic polymer layer and the anionic polymer It has a multilayer structure composed of layers. Note that the electron donating group has a property that a functional group tends to push out (donate) an electron from its own side.

The light absorbing layer A (A _{1 to} A ₁₄ ) formed by the alternate adsorption method is composed of a cationic polymer and an anionic polymer having a photosensitizing group introduced therein, or a cationic polymer and an anionic polymer having a photosensitizing group introduced therein. It is composed of an alternating adsorption film of a polymer, and the alternate adsorption film has a multilayer structure composed of at least one set of the cationic polymer layer and the anionic polymer layer. The photosensitizing group has a property of being activated when light energy is absorbed.

The electron transport layer N (N ₆ , N ₇ , N ₈ , N ₁₃ , N ₁₄ ) formed by the alternating adsorption method is composed of a cationic polymer and an anionic polymer having an electron-accepting group introduced, or an electron-accepting polymer. The layer comprises an alternately adsorbed film of an anionic polymer and a cationic polymer into which a group is introduced, and the alternately adsorbed film has a multilayer structure composed of at least one pair of the cationic polymer layer and the anionic polymer layer. Note that the electron-accepting group has a property of trying to attract (accept) an electron to its own side.

Here, the light absorbing layer A absorbs light energy.
The hole transport layer P has a function of transferring holes generated by light absorption to an adjacent electrode (the first electrode layer 51) by the electron donating group donating an electron. Such a function is performed if the highest occupied electron level of the electrode layer 51, the hole transport layer P, and the light absorption layer A is configured to be improved as approaching the first electrode layer 51. .

  The electron transport layer N has a function of transferring electrons generated by light absorption to an adjacent electrode (second electrode layer 52) by receiving an electron accepting group. Such a function is executed if the lowest vacancy level of the transport layer N and the second electrode layer 52 is configured to decrease as approaching the second electrode layer 52.

  The electron donating layer E is disposed at the interface between the hole transporting layer P and the light absorbing layer A, and has a higher electron donating property than the first electron donating group of the hole transporting layer P. It is composed of a functional group.

Note that the photoelectric element 50 ₁ in FIG. 12 (1) has a configuration corresponding to claim 13. 12 photoelectric element 50 ₂ (2) has a configuration corresponding to claim 14. 12 photoelectric device 50 ₃ (3) has a configuration corresponding to claim 15. The photoelectric elements 50 ₄ and 50 ₅ of FIGS. 12 (4) and 12 (5) have a configuration corresponding to claim 16. 12 (6) The photoelectric element 50 _{6-50 8} to (8) has a configuration corresponding to claim 17. 12 (9) The photoelectric element 50 _{9-50 14} - (14) has a configuration corresponding to claim 18 and 19.

12 (1) (4) (6) The photoelectric element 50 shown in (7) (50 _1, 50 _4, 50 _6, 50 ₇₎ is of a type wherein at least a light-absorbing layer A is formed by the alternate adsorption method Te, the light-absorbing layer a, a hole transport layer P, an electron transport layer thin layer composed of three layers _{N 60 (60 1, 60 4} , 60 6, 60 7) a pair of electrodes (a first electrode layer 51, the second electrode layer 52).
In the photoelectric device 50 ₄ of (4), in addition to the light absorbing layer A ₄ , the hole transport layer P ₄ is further formed by the alternate adsorption method. In the photoelectric element 50 ₆ (6), in addition to the light-absorbing layer A _6, it is further also electron transport layer N ₆ formed by alternate adsorption method. In the photoelectric element 50 ₇ (7), in addition to the light-absorbing layer A _7, it is further hole transport layer P ₇ and the electron transporting layer N ₇ also formed by alternate adsorption method.

Next, FIG. 12 (2) photoelectric device 50 shown in (3) (50 _2, 50 _3), a configuration in which respect the photoelectric element 50 ₁ is omitted electron transport layer N ₁ or the hole transport layer P ₁ respectively ing. The photoelectric device 50 ₅ shown in FIG. 5 has a configuration omitting the electron transporting layer N ₄ to the photoelectric element 50 ₄ shown in (4).
As described above, the photoelectric element 50 (50 ₂ , 50 ₃ , 50 ₅ ) has any of the hole transport layers P ₂ , P ₅ or the electron transport layer N ₃ provided that the light absorption layer A is an essential component. Due to the hole or electron transport action, the photoelectric conversion action of the photoelectric element 50 can be exhibited.

Next, FIG. 12 (9) to the photoelectric element 50 shown in (14) (50 _9, 50 _10, 50 _11, 50 _12, 50 _13, 50 ₁₄₎ includes a photoelectric device 50 described above, respectively (50 _1, 50 ₂ , 50 ₄ , 50 ₅ , 50 ₆ , 50 ₇ ), in which an electron donating layer E is provided at the interface between the hole transporting layer P and the light absorbing layer A. A thin film layer 60 ₉ , 60 ₁₀ , 60 ₁₁ , 60 ₁₂ , 60 ₁₃ , 60 ₁₄ composed of four layers of a transport layer P, an electron donating layer E, and an electron transport layer N) is used as a pair of electrodes (first electrode layer). 51, the second electrode layer 52).
In the drawings, the electron donating layer E is formed by the alternate adsorption method, but the forming method is not limited to this.

By disposing the electron donating layer E in this manner, when the holes generated in the light absorbing layer A are transported to the first electrode layer 51, the electron donating layer E having excellent hole separation characteristics can be obtained. the positive hole hole transport layer P having excellent transport properties becomes possible to function sharing respectively, high efficiency of the photoelectric element 60 (60 _{9-60 14)} is achieved.

Here, the light absorption layer A (A _{1 to} A ₁₄ ) formed by the alternate adsorption method is composed of, for example, a ruthenium complex (a) shown in FIG. The hole transport layer P (P ₄ , P ₅ , P ₇ ) formed by the alternate adsorption method is, for example, a ferrocene-containing polymer (b) shown in FIG. 13 and a poly (3,4-ethylenedioxy). (Thiophene) / poly (4-styrene sulfonate) (PEDOT / PSS) (c). Further, the electron transport layer N (N ₆ , N ₇ , N ₈ , N ₁₃ , N ₁₄ ) formed by the alternate adsorption method is composed of, for example, a fullerene polymer complex (nu) shown in FIG. .

Next, as the hole transport layer P (P ₁ , P ₂ , P ₆ ) formed by a method other than the alternate adsorption method, for example, the first electrode layer 51 (51 ₁ , 51 ₂ , 51 ₆ ) or The ferrocene-containing polymer (b) formed by coating the light absorbing layer A (A ₁ , A ₂ , A ₆ ), and the hole transport layer P (P ₄ , P ₅ and P ₇ ) are, for example, a ferrocene-containing polymer (b) shown in FIG. 13, poly (3,4-ethylenedioxythiophene) / poly (4-styrenesulfonate) (PEDOT / PSS) ( C). (C), polyhexylthiophene (2), poly (2-methoxy-5- (2'-ethylhexyloxy) -1,4-phenylenephenylene) (poly (2-methoxy-5- (2'-ethylhexyloxy) -1,4-phenylenevinylene) (e), liquid crystal-based substance dioctylterthiophene (he), or electrolyte-based iodine / potassium iodide in acetonitrile (g), or light Substances such as sexithiophene (h) and pentacene (h) formed by vapor deposition on the absorption layer A are exemplified.

Next, as the electron transporting layer N (N ₁ , N ₃ , N ₄ , N ₉ , N ₁₁ ) formed by a method other than the alternate adsorption method, for example, the second electrode layer 52 (52 ₁ , 52 ₃₎ , 52 ₄ , 52 ₉ , 52 ₁₁ ) or the light absorbing layer A (A ₁ , A ₃ , A ₄ , A ₉ , A ₁₁ ). / Polystyrene blend film (（), fullerene / polyvinyl naphthalene blend film (ヲ), or hexyloxyphenyl-hexyloxybiphenyloxadiazole (wa), which is a liquid crystal material, or an electrolyte material Methyl viologen (f), or fullerene (yo) formed by vapor deposition on the light absorbing layer A, 8-humanquinoxyline, aluminum salt (ta), or Substance such as the second electrode layer 52 fullerene carboxylic acid formed by the surface decor (Les) and the like.

The above-mentioned fullerene-based electron accepting groups shown in (nu), (le), (ヲ), (yo), and (re) are obtained by using a metal oxide such as SnO ₂ as the second electrode layer 52, Can be adsorbed. When the light absorbing layer A is formed on the electron transporting layer N formed of these fullerene-based electron accepting groups by the alternate adsorption method, the effect of improving the light absorption efficiency is obtained by increasing the contact area at the interface.
When the electron transporting layer N is formed by the fullerene polymer complex (nu) by an alternate adsorption method, it is possible to simultaneously control the thickness of the electron transporting layer N and increase the area of the contact interface with the light absorbing layer A. Becomes possible.

Further, FIG. 12 (9), as shown in - (14), in the photoelectric element 60 that includes an electron donor layer E (60 ₉ to 60 _14), electron-donating also electron donating layer E is than the hole-transporting layer P As shown in FIG. 13, for example, as shown in FIG. 13, the combination of the hole transport layer P and the electron donating layer E is composed of poly (3,4-ethylenedioxythiophene) / poly (4- Styrene sulfonate) (PEDOT / PSS) (c) and ferrocene-containing polymer (b), polyhexylthiophene (2) and ferrocene-containing polymer (b), poly (2-methoxy-5- (2'-ethyl) (Hexyloxy) -1,4-phenylene phenylene) (e) and ferrocene-containing polymer (b), dioctylterthiophene (f) and ferrocene-containing polymer (b), iodine / potassium iodide in acetonitrile ( G) and ferrocene-containing polymer ( ), Sexithiophene (Sexithiophene) (h) ferrocene-containing polymer (B), and a combination of pentacene (Li) ferrocene-containing polymer (b).

Then, one of the first electrode layer 51 and the second electrode layer 52 is formed of a transparent electrode, and specific examples thereof include ITO (indium tin oxide) and SnO ₂ . As the other counter electrode, specifically, Al, Au, Pt, or the like can be given.

  As described above, if at least the light absorption layer A among the layers constituting the photoelectric element 50 is formed by the alternate adsorption method, the light absorption layer A can be formed with a highly accurate film thickness by an extremely simple method. It can be formed as a controlled thin film. It is clear from experimental results that the optimum thickness of the light absorption layer A, which allows the photoelectric element 50 to exhibit its photoelectric conversion characteristics to the maximum, is included in the range of 1 nm to 30 nm. If the thickness of the light absorption layer A is larger than this optimum value, the moving distance of the excitons (pairs of electrons and holes) becomes longer and the excitons are deactivated. Is reduced, resulting in a decrease in photoelectric conversion characteristics. As described above, the photoelectric device 50 having the light absorption layer A formed by the alternate adsorption method exhibits high photoelectric conversion characteristics, is maintained without deteriorating the characteristics, and has a further excellent quality. Can be supplied in large quantities at low cost.

  When all the manufacturing steps are performed by the alternate adsorption method as in the photoelectric device 50 shown in FIGS. 12 (5), (7), (8), (12), and (14), the advantages of the wet process are inexpensive and large. The characteristics that can be produced can be maximized, and the production of the photoelectric element 50 having a larger area can be handled.

  When a part of the production process of the photoelectric element 50 includes a coating process as a layer forming method other than the alternate adsorption process, not only a water-soluble polymer but also a polymer soluble in an organic solvent is used. Can be applied.

  In addition, when a part of the production process of the photoelectric element 50 includes a formation process by vapor deposition as a layer formation method other than the alternate adsorption method, a high-density functional molecular layer can be manufactured.

  When a part of the production process of the photoelectric element 50 includes a formation process using an electrolyte as a layer formation method other than by the alternate adsorption method, a favorable condition at the interface with the adjacent electrode (the first electrode layer 51) is obtained. A simple joining is realized. Thereby, high efficiency of photoelectric conversion is realized.

  In addition, in the case where a part of the process of forming the photoelectric element 50 includes a liquid crystal forming step as a layer forming method other than the alternate adsorption method, the interface between the adjacent electrode (the second electrode layer 52) and the adjacent electrode (the second electrode layer 52) is formed. In addition to realizing good bonding, a photoelectric element having excellent durability is realized by taking advantage of the property of being non-volatile.

  When a part of the step of forming the photoelectric element 50 includes a formation step using an electrolyte as a layer formation method other than by the alternate adsorption method, a favorable condition at the interface with the adjacent electrode (the second electrode layer 52) is obtained. A simple joining is realized. Thereby, high efficiency of photoelectric conversion is realized.

  In the case where a part of the step of forming the photoelectric element 50 includes a step of forming a layer by electrode modification as a layer forming method other than by the alternate adsorption method, fullerene having a high electron transporting property is formed at a high concentration by a wet process. It will be possible to introduce. The direct adsorption is expected to improve the electron injection efficiency.

  Next, the alternate adsorption method will be described. In the alternate adsorption method, a cationic polymer aqueous solution and an anionic polymer aqueous solution are prepared in separate containers, and a substrate having an initial surface charge is alternately immersed in these containers to have a multilayer structure on the substrate. An alternately adsorbed film that is an ultrathin film can be obtained. For example, a negative charge is given to the surface of the ITO substrate as an initial surface charge. Then, if the ITO substrate whose surface is negatively charged is immersed in a solution containing a cationic polymer, the cationic polymer is adsorbed to the surface by Coulomb force until at least the surface charge is neutralized. Is formed. The surface portion of the ultra-thin film thus formed is positively charged. Then, when this substrate is immersed in a solution containing an anionic polymer, the anionic polymer is adsorbed by Coulomb force, and a single-layer ultrathin film is formed. In this way, by alternately immersing the substrate in the two containers, an ultra-thin layer made of a cationic polymer and an ultra-thin layer made of an anionic polymer could be formed alternately, and a multilayer structure was obtained. A composite thin film can be formed.

FIG. 1 is a conceptual diagram showing a manufacturing principle of a general alternating adsorption film. In FIG. 1, a first tank (2) contains an aqueous solution of a cationic polymer, and a second tank (3) contains an aqueous solution of an anionic polymer. Here, a substrate (1) having a positive or negative initial surface charge on its surface, for example, an ITO substrate is prepared. FIG. 2A is a conceptual diagram showing a state in which the ITO surface is negatively charged by performing the ozone cleaning treatment on the ITO substrate surface. When the negatively charged substrate (1) is put into the first tank (2), the cationic polymer (4) is adsorbed on the surface of the substrate 1 by Coulomb force. An electron-donating group (5) is introduced into the cationic polymer (4). FIG. 2B schematically shows this state. Subsequently, the substrate in the state shown in FIG. 2B is put in the second tank (3). Then, the anionic polymer (6) is adsorbed on the surface of the cationic polymer by Coulomb force. FIG. 2C schematically shows this state. As described above, if the substrate (1) is alternately immersed in the first tank (2) and the second tank (3), the layer composed of the cationic polymer and the layer composed of the anionic polymer are alternately formed. A hole transporting (electron donating) layer having a multilayer structure containing the electron donating group (5) is formed by adsorption. This number of layers can be set freely in one or more layers by the number of adsorption operations.

After the predetermined number of times of alternate adsorption, another type of electron donating group or photosensitizing group (7) is replaced with the cationic polymer (4) into which the electron donating group (5) is introduced. By using the introduced cationic polymer (4), as shown in FIG. 3, an electron donating group (in the hole transporting (electron donating) layer) or in the adjacent light absorbing (photosensitizing) layer is formed. The highest occupied electron level different from 5) can be provided. Here, by appropriately selecting the electron donating group (5) or another kind of electron donating group or photosensitizing group (7) in comparison with the level of ITO, these electron donating groups (5) A structure is formed in which the highest occupied electron level of the group of the photosensitizing group (7) is gradually improved as approaching ITO.
In the above example, the case where the electron-donating group (5) or another type of group (7) is introduced into the cationic polymer has been described, but it is also possible to introduce the electron-donating group (5) into the anionic polymer.

  The repulsion due to the Coulomb force between the segments in the polymer molecule increases or decreases depending on conditions such as the concentration, pH value, and adsorption time of the electrolyte polymer used in the adsorption treatment. It will depend on these conditions. Therefore, depending on the setting of these conditions, it is possible to form a very thin film or a relatively thick film.

As described above, when a certain thickness is reached, the Coulomb force does not act due to electrical neutralization, so adsorption will reach a saturation point, but until reaching this saturation point, the longer the immersion time, the longer the immersion time The film thickness increases.
The thickness of the adsorption layer adsorbed on the surface by one immersion of the substrate can be controlled in the range of 1 nm to several tens nm, although it varies depending on the given conditions. Then, by alternately immersing the cationic polymer solution and the anionic polymer aqueous solution, the number of layers of the adsorption layer is increased, and the total film thickness is reduced from 1 nm to 1 μm in units of the film thickness of one layer. Quantitative control can be performed.

  FIG. 1 shows an example in which two water tanks (2) and (3) are used to explain the principle of the alternate adsorption method. However, in practice, the two water tanks (2) and (3) are used. When a process of alternately immersing the substrates (1) is performed, when the substrate is pulled up from one water tank and put into the other water tank, the liquid in the original water tank adheres to the surface. It will gradually become mixed. Therefore, in practice, it is preferable to prepare a cleaning tank and perform a rinsing bath.

  In the present invention, the anionic polymer and the cationic polymer constituting the alternating adsorption film are not particularly limited. Preferred examples of the anionic polymer include a polymer having a carboxylic acid and a polymer having a sulfonic acid. Specifically, examples of the anionic polymer having a carboxylic acid include polyacrylic acid, polymethyl acrylate, and poly (thiophen-3-acetic acid). Examples of the anionic polymer having sulfonic acid include polystyrenesulfonic acid, polyvinylsulfonic acid, poly-3-methacrylic acid-3-sulfopropyl, polyanilinesulfonic acid, and poly (3-thiophenealkanesulfonic acid).

Preferable examples of the cationic polymer include a polymer having an ammonium group and a polymer having a pyridyl group. Specifically, examples of the cationic polymer having an ammonium group include polyethyleneimine, polyamylamine, and polycholine methacrylate. Examples of the cationic polymer having a pyridyl group include polyvinyl pyridine, polyvinyl ethyl pyridine, and poly (para-methylpyridinium vinylene).
These anionic polymer and cationic polymer are disclosed in detail in Non-Patent Document 4 described above.

  In the present invention, various sensitizing dyes are preferably used as the photosensitizing group introduced into the anionic polymer and / or the cationic polymer. Specifically, as the sensitizing dye, a ruthenium complex-based compound having a high extinction coefficient and high light resistance (see FIG. 13A) is most promising. Various compounds exist in the ruthenium complex depending on the ligand. For example, a tris (2,2'-bipyridine) ruthenium (II) complex, an N3 dye used in a Gretzell cell, a black dye, and the like can be mentioned. Other examples include porphyrin-based dyes and phthalocyanine-based dyes.

In addition, a wide variety of dyes can be used, which is disclosed in detail in Non-Patent Document 5 described above. Specifically, spiro compounds, ferrocene, fluorenone, fulgide, imidazole, perylene, phenazine, phenothiazine, polyene (carotene, maleic acid derivative, pyrazolone, stilbene), azo compounds (dithizone, formazan), quinones (acridone, anthrone, Indantrene, pyrylene dione, biolanthrone), indigo (indirubin, oxyindigo, thioindigo), diphenylmethane, triphenylmethane (fluorane, fluorescein, rhodamine), polymethine (cyanine, pyridinium, pyrylium, quinolinium, rhodamine), acridine, acridinone, carbostyril , Coumarin, diphenylamine, quinacridone, quinophthalone, phenoxazine, phthaloperinone, porphine, chlorophyll Phthalocyanine, crown, squarylium, tetrathiafulvalene, and the like.
The method for introducing these dyes as a photosensitizing group into an anionic polymer and / or a cationic polymer is not particularly limited, and a known method can be used.

In the present invention, as the hole transporting (electron donating) layer, a layer obtained by introducing an electron donating compound having a low ionization potential as a hole transporting material into an anionic polymer and / or a cationic polymer is preferably used. Preferred examples of the hole transport material include amine compounds, aromatic compounds, and heteroaromatic compounds, including the compounds shown in FIG. Specific examples include thiophene compounds, ferrocene derivatives, carbazole derivatives, pyrrole compounds, aniline compounds, tetrathiafulvalene derivatives, diamine compounds, phthalocyanine compounds, hydrazone compounds, and the like.
Non-Patent Document 5 describes the details of these hole transport materials and their ionization potentials.

In the present invention, the electron transporting (electron accepting) layer is preferably formed by introducing an electron accepting compound having a high electron affinity as an electron transporting material into an anionic polymer and / or a cationic polymer. Preferred examples of the electron transport material include aromatic compounds mainly having an electron withdrawing group, fullerene derivatives, and the like, including the compounds shown in FIG. Specific examples include fullerene derivatives, oxadiazole derivatives, oxazole derivatives, perylene derivatives, naphthalene derivatives, metal complexes, and the like.
Non-Patent Document 5 describes details of these electron transport materials and their electron affinities.

FIG. 4 is a schematic diagram showing the energy levels of the photoelectric device of the present invention. Hereinafter, the operation of the photoelectric device of the present invention will be described with reference to FIG.
FIG. 4 (a) shows a photoelectric structure including a first electrode layer (11), a hole transport layer (12), a light absorption layer (13), an electron transport layer (14), and a second electrode layer (15). Element (10). At least one of these layers is composed of an alternate adsorption film formed by an alternate adsorption method of a cationic polymer and / or anionic polymer in which at least a part of a cationic polymer and / or an anionic polymer is modified with a functional group.

  In addition, the energy levels of the first electrode layer (11), the hole transport layer (12), the light absorption layer (13), the electron transport layer (14), and the second electrode layer (15) have a potential gradient. have. For example, in the first electrode layer (11), the hole transport layer (12), and the light absorption layer (13), the highest occupied electron level increases toward the first electrode layer (11). . Such a potential gradient can be provided by adjusting the chemical structure of the electron donating group introduced into each layer of the alternating adsorption film constituting the hole transport layer (12). In the light absorption layer (13), the electron transport layer (14), and the second electrode layer (15), the lowest vacancy level decreases toward the second electrode layer (15). Such a potential gradient can be achieved by adjusting the chemical structure of the electron-accepting group introduced into each layer of the alternating adsorption film constituting the electron transporting layer (14).

  The light is separated into holes and electrons in the light absorbing layer (13) by the energy of the incident light. The holes move in the hole transport layer (12) and reach the first electrode layer (11). The electrons move in the electron transport layer (14) and reach the second electrode layer (15). As a result, a potential difference occurs between the first electrode layer (11) and the second electrode layer (15). Such smooth movement of holes or electrons is caused by the gradient of the highest occupied electron level between the light absorption layer and the first electrode layer via the hole transport layer or the electron transport layer as described above. This is achieved by the lowest vacancy level gradient between the light absorbing layer and the second electrode layer.

  FIG. 4B shows a photoelectric device (10) including a first electrode layer (11), a light absorption layer (13), an electron transport layer (14), and a second electrode layer (15). At least one of these layers is composed of an alternating adsorption film in which at least a part of a cationic polymer and / or an anionic polymer has a functional group introduced therein, and a cationic polymer and an anionic polymer are formed by an alternate adsorption method. In addition, the energy levels of the first electrode layer (11), the light absorbing layer (13), the electron transport layer (14), and the second electrode layer (15) have a potential gradient. For example, in the first electrode layer (11) and the light absorbing layer (13), the highest occupied electron level of the light absorbing layer (13) is lower than the level of the first electrode layer (11). . In the light absorption layer (13), the electron transport layer (14), and the second electrode layer (15), the lowest vacancy level decreases toward the second electrode layer (15).

  The light is separated into holes and electrons in the light absorbing layer (13) by the energy of the incident light. The holes reach the first electrode layer (11). The electrons move in the electron transport layer (14) and reach the second electrode layer (15). As a result, a potential difference occurs between the first electrode layer (11) and the second electrode layer (15).

  FIG. 4C shows a photoelectric device (10) including a first electrode layer (11), a hole transport layer (12), a light absorbing layer (13), and a second electrode layer (15). At least one of these layers is composed of an alternating adsorption film in which a cationic polymer and / or anionic polymer having a functional group introduced into at least a part of a cationic polymer and / or an anionic polymer is formed by an alternate adsorption method. In addition, the energy levels of the first electrode layer (11), the hole transport layer (12), the light absorbing layer (13), and the second electrode layer (15) have a potential gradient. For example, in the second electrode layer (15) and the light absorbing layer (13), the lowest vacancy level of the light absorbing layer (13) is higher than the level of the second electrode layer (15). Further, in the light absorption layer (13), the hole transport layer (12), and the first electrode layer (11), the highest occupied electron level increases toward the first electrode layer (11). .

The light is separated into holes and electrons in the light absorbing layer (13) by the energy of the incident light. The holes move in the hole transport layer (12) and reach the first electrode layer (11). The electrons reach the second electrode layer (15). As a result, a potential is generated between the first electrode layer (11) and the second electrode layer (15).
Next, an example of a photoelectric conversion device represented by a solar cell will be described.

FIG. 5 is a schematic sectional view showing an example of the photoelectric conversion device according to the present invention. Hereinafter, an example in which the photoelectric conversion device is stacked from the electron transport layer (electron donating layer) will be described, but a structure in which the photoelectric conversion device is stacked from the hole transport layer (electron accepting layer) in reverse order is also possible. A transparent conductive film (22) as a first electrode layer is formed on a glass substrate (21). As this conductive film, a conductive film typified by In ₄ Sn ₃ O ₅ called ITO is generally used. In addition, zinc oxide containing indium or the like can be used. An electron donating layer (23) made of an electron donor is formed on the upper surface of the transparent conductive film. As the electron donor, for example, a copolymer of choline methacrylate chloride and vinylferrocene can be used. First, a thin-film layer in which this copolymer and polyacrylic acid (Poly (acrylic acid)) are repeatedly laminated is formed on the upper surface of the transparent electrode to form an electron donating layer (23). The electron donating layer may be a two-layer film including a single-layer electron donor thin film, or may have a multilayer structure in which a copolymer and poly (acrylic acid) are repeatedly laminated. In this case, if there are many portions where the transparent electrode film (22) and the light absorbing layer (24) are in direct contact, it is considered that the photoelectric conversion efficiency is reduced. Therefore, the exposed portion of the transparent conductive film can be ignored as the electron donor layer. It is desirable to have a multilayer structure to the extent.

As shown in FIG. 6, the light absorbing layer (24) can be multilayered by alternately adsorbing the anionic polymer (31) and the cationic polymer (32). In this case, by forming a multilayer, the amount of photosensitizing group per apparent surface area through which light passes can be increased, and the amount of light absorbed can be increased. An increase in the amount of light absorption can lead to an improvement in photoelectric conversion efficiency. By changing the adsorption conditions and the number of adsorption layers, the entire film thickness is formed in the range of 1 nm to 1 μm. FIG. 6 shows an example in which the light absorbing layer (24) is multi-layered. As the light absorbing layer, an alternately laminated film of a polycation and a polyanion having various dyes in their side chains can be used. This portion is left as it is, for example, a polycation layer (32) and a polyanion layer (31) each having a tris (2,2'-bipyridyl) ruthenium complex derivative in a side chain. Polyacrylic acid (Poly (acrylic acid)) which is alternately laminated can be used.

  FIG. 7 is a schematic diagram showing a photoelectric conversion device having a structure in which a grid wiring (29) is formed under a transparent conductive film (22). FIG. 7A is a sectional view, and FIG. 7B is a top view. Since the transparent conductive film (22) is generally a material having a high electric resistance, the resistance component for transferring electrons to the electron donating layer may be increased and the photoelectric conversion efficiency may be reduced. By forming the grid wiring (29) under the transparent conductive film, it is possible to reduce the moving distance of the electrons moving on the transparent conductive film, and to reduce the electric resistance and increase the photoelectric conversion efficiency. Metal wiring such as copper, silver, solder, aluminum, and gold can be applied to the grid wiring.

  The grid wiring may be formed on the transparent conductive film (22). In this case, the surface of the grid wiring may be covered with an insulating layer or the like in order to prevent the grid wiring from directly contacting the electron donating layer (23).

  As the electron accepting layer (25), a material having a high electron accepting ability such as fullerene is preferably used. The electron accepting layer may be a single layer film or a multilayer film as in the case of the electron donating layer.

  The electrode (26) serving as the second electrode layer can be made of aluminum, magnesium, gold, platinum, or the like. Generally, these metal films for electrodes are formed by a vapor deposition method or the like.

  Electricity generated by the photoelectric conversion reaction is taken out to the outside by the conducting wire (28). The conductive wire (28) is connected to the transparent conductive film (22) and the electrode (26) in a structure like a terminal contact (27) using a contact material such as silver paste or solder.

  As described above, the present invention has been described by taking the photoelectric element, particularly the solar cell as an example, but the present invention is not limited to this. The polymer thin film having an alternating laminated structure of the present invention is applied to an element for an optical-electronic circuit such as an optical thin film transistor, an optical memory, an optical sensor, a light emitting diode, a drum film for a copying machine, etc. by utilizing its photoelectric conversion function. Is also possible.

Hereinafter, a production example of the polymer thin film of the present invention will be described.
[Example 1]
Three types of polymers such as a cationic polymer (Fc) having ferrocene as an electron donating compound, a cation polymer (Cz) having carbazole as a photosensitizing compound, and an anionic polymer (PAA) as shown in the following chemical formula 1. An electrolyte was used.

Three layers of Fc / PAA layers were laminated by alternately immersing the hydrophilically treated ITO substrates in a 0.01 M Fc aqueous solution and a PAA aqueous solution. Subsequently, three Cz / PAA layers were stacked by alternately immersing the hydrophilically treated ITO substrates in a 0.01 M Cz aqueous solution and a PAA aqueous solution. A triode was formed using the prepared alternately adsorbed film as a working electrode, Pt as a counter electrode, and Ag / AgCl as a reference electrode. A predetermined concentration of methyl viologen (MV ²⁺ ) was added to the electrolyte as an electron acceptor.

FIG. 8 shows the potential of each functional layer of the produced photoelectrically functional polymer thin film. In this alternately laminated film, a cathode current is generated from ITO to MV ²⁺ due to the photoexcitation of Cz by sequentially giving potential gradients to the respective layers of ITO, Fc, Cz, Cz * and MV ^2+. The membrane structure is designed.

Photocurrent measurement was performed on the manufactured triode. A 500 W xenon lamp was used as a light source, and the light was spectrally irradiated to 300 to 400 nm, which is the absorption band of the sensitizing compound, using various optical filters. The light intensity after the spectroscopy was about 10 mW · cm ⁻² . FIG. 9 shows the measurement results. The lower line is the result of only ITO, and almost no photocurrent was observed. On the other hand, in the photoelectrically functional polymer thin film, generation of a photocurrent indicated by the upper line was observed. A minus sign on the vertical axis indicates a cathode current, and indicates that a photocurrent is generated according to the above-described potential gradient. As described above, it has been demonstrated that by constructing a photoelectric functional polymer thin film having an alternately laminated structure, a photocurrent can be obtained according to a designed potential gradient.

[Example 2]
A similar photocurrent was generated when a ruthenium-containing cationic polymer (Ru) represented by the following chemical formula 2 was used instead of the carbazole cationic polymer (Cz).

[Example 3]
In addition to the above, an alternately laminated photoelectrically functional thin film was constructed using a photoelectrically functional polymer electrolyte represented by the following chemical formula 3, and photocurrent measurement was performed.

Further, the following structure was constructed, and a similar photoelectric conversion effect was obtained.
ITO / PEDOT / Ru
ITO / PEDOT / Ru / C60
ITO / PPV / Ru
ITO / PPV / Ru / C60
FIG. 10 shows the results of photocurrent measurement of a photoelectric device having a layer structure of ITO / PEDOT / Ru / C60 / Al. A 500 W xenon lamp was used as a light source, and monochromatic light of 460 nm was converted by a monochromator. The light intensity after the spectroscopy was about 10 mW cm ^-2 .

[Example 4]
Further, the following structures were manufactured.
As the sensitizing dye, a ruthenium complex having a high light absorption coefficient and high light resistance was used, and an appropriate thickness was set so as to maximize the photosensitizing efficiency. An electron-donating layer and an electron-accepting layer were disposed on both sides of the sensitizing layer in order to efficiently realize charge separation from the sensitizing molecule and suppress charge recombination. In order to obtain a photocurrent, the electron donating layer and the electron accepting layer must also function as a hole transport layer and an electron transport layer, respectively. These layers need to be made as thin as possible because charge transport efficiency decreases as the film thickness increases. However, at least one of the layers needs to have a thickness of 10 nm to 1 μm in order to constitute an element. Since the mobility for electron transport is lower than that for hole transport, the thickness of the electron transport layer was made as thin as possible, and the hole transport layer was designed to be thick. Therefore, since the probability of charge recombination increases with respect to hole transport, it is desirable to use two or more materials for the hole transport layer in order to suppress recombination. A system as shown in FIG. 11 was constructed as a structure satisfying the above requirements, and a similar photoelectric conversion effect was obtained.

[Example 5]
Next, the photoelectric element 50 ₇ forming method shown in FIG. 12 (7) 3-component adsorption system. Here, the hole transport layer P ₇ is made of a ferrocene-containing polymer (b), the light absorption layer A ₇ is made of a ruthenium complex-containing polymer (a), and the electron transport layer N ₇ is made of a fullerene polymer complex (nu). It was decided to be composed.

(Hydrophilic treatment of transparent electrode)
A transparent electrode (first electrode layer 51 ₇ ) such as an ITO substrate is subjected to ultrasonic treatment for 20 minutes using a toluene, acetone or ethanol solution, and then an alkaline piranha solution (distilled water: 30% hydrogen peroxide solution). : 25% concentrated aqueous ammonia = 5: 1: 1) The substrate surface was negatively charged by boiling at 80 ° C for 15 minutes. The substrate surface can also be made hydrophilic by performing UV-ozone treatment for one hour using an ozone cleaner instead of the piranha solution.

(Preparation of photosensitized polycation (Ru) solution)
Choline methacrylate (choline methacrylate) and bipyridyl methacrylate (4- (methacryloylmethyl) -4'-methyl-2,2'-bipyridine) were radically copolymerized in ethanol to obtain a copolymer. After reprecipitation purification using ethanol as a good solvent and acetone as a poor solvent, a polycation having a ruthenium complex in the side chain was synthesized by a ligand exchange reaction with a bis-2,2'-bipyridyldichlororuthenium (II) complex. After complexation, purification was carried out by reprecipitation using ethanol as a good solvent and methylene chloride as a poor solvent. This polymer was dissolved in ultrapure water to obtain a 10 mM aqueous solution (photosensitized polycation).

(Preparation of electron-donating polycation (Fc) solution)
Radical copolymerization of choline methacrylate and vinyl ferrocene in ethanol yielded a polycation having ferrocene in the side chain. After reprecipitation and purification using acetone as a poor solvent and ethanol as a good solvent, washing with acetonitrile was performed. This polymer was dissolved in ultrapure water to obtain a 10 mM aqueous solution (electron-donating polycation).

(Preparation of electron accepting polycation (C60) solution)
4 mg of C ₆₀ C (COOH) ₂ was added to 21 mL of a polyethyleneimine methanol solution (2.326 mM) and stirred. This methanol solution was concentrated to 5 mL using an evaporator, and 45 mL of ultrapure water was added. Ultrasonic treatment was performed for 6 minutes to enhance dispersibility.

(Preparation of polyanion (PAA) solution)
An aqueous solution of sodium hydroxide was added in an appropriate amount to prepare a 35 wt% polyacrylic acid aqueous solution (polyanion) adjusted to pH = 6.5.
(Rinse solution)
The ion-exchanged water was distilled, and ultrapure water was produced through an ultrapure water production apparatus (Barnstead II).

(Preparation of alternate adsorption film)
After making the substrate surface hydrophilic, 1) polycation solution (adsorption), 2) drying, 3) ultrapure water (rinsing), 4) drying, 5) polyanion solution (adsorption), 6 A series of adsorption operations consisting of)) drying, 7) ultrapure water (rinse), and 8) drying are repeated a predetermined number of times.
Specifically, 30 mL of each of the polymer electrolyte aqueous solution and ultrapure water were added to 50 (50 mm) weighing bottles, respectively, and placed on a turntable in a predetermined order. The adsorption conditions were immersion time of 5 minutes and rinsing time. The drying time was set at 3 minutes, the drying time was 2 minutes, the temperature was 21-24 ° C., and the humidity was 50-60%, and the substrate was pulled up and down at a rate of 0.6 mm / s using a stepping motor.

  First, the hydrophilically treated ITO substrate was immersed in the Fc solution for 5 minutes, pulled up, dried for 2 minutes, immersed in ultrapure water for 3 minutes, and then dried for 2 minutes. Subsequently, it was immersed in a PAA solution for 5 minutes, pulled up, dried for 2 minutes, immersed in ultrapure water for 3 minutes, and dried for 2 minutes after pulling up. As a result, a pair of Fc and PAA films is formed on the ITO substrate. By repeating this operation n times, n pairs of Fc / PAA films are produced. Hereinafter, this film is referred to as an Fc (electron donating) film.

  Next, the same operation is repeated m times by changing the Fc solution to the Ru solution, whereby m pairs of Ru / PAA films can be produced. Subsequently, the same operation is repeated once while changing the Fc solution to the C60 solution, whereby one pair of C60 / PAA films can be produced. Thus, ITO / Fc (n-membrane) / Ru (m-membrane) / C60 (l-membrane) can be produced. Here, an alternate adsorption film of ITO / Fc / Ru / C60 with n = 4, m = 4, l = 4 was prepared.

(Preparation of Counter Electrode (Second Electrode Layer 52 ₇ ))
Aluminum was vapor-deposited on the alternately adsorbed film as a counter electrode (second electrode layer 52 ₇ ) using a vacuum vapor deposition apparatus. Evaporation was performed at an evaporation speed of 2 nm / s for 50 seconds to obtain an aluminum electrode having a thickness of 100 nm. As a result of the photocurrent measurement, a similar photoelectric conversion effect was obtained.

[Example 6]
Next, a photoelectric device 50 ₄ shown in FIG. 12 (4) shows the case of including a step of forming the electron-transporting layer N by coating. Here, the hole transport layer P ₄ was made of ferrocene (b), and the light absorbing layer A ₄ was made of a ruthenium complex (a), and an ITO / Fc / Ru film was produced by an alternate adsorption method in the same manner as described above. Then, as the electron transport layer N, an orthodichlorobenzene solution (（) in which 0.2 wt% of polystyrene and 0.6 wt% of C60 were dissolved was spin-cast on the substrate.
Then, after vacuum dried in a desiccator, aluminum was obtained a photoelectric element 50 ₄ is deposited by a method of producing the as the counter electrode (the second electrode layer 52 _4). As a result of the photocurrent measurement, a similar photoelectric conversion effect was obtained.

[Example 7]
Next, a photoelectric device 50 ₄ shown in FIG. 12 (4) shows the case where by the electrolyte system comprises a step of forming the electron-transporting layer N.
On the surface of the light absorption layer A (Ru film) of the ITO / Fc / Ru film produced in the same manner as described above, a counter electrode of a platinum net is arranged adjacently. Then, potassium chloride was used as a supporting electrolyte, and an aqueous solution containing methyl viologen as an acceptor molecule was used. As a result of the photocurrent measurement, a similar photoelectric conversion effect was obtained.

[Example 8]
Next, a photoelectric device 50 ₄ shown in FIG. 12 (4) shows the case where due to deposition system comprising the step of forming the electron-transporting layer N.
Was prepared in a similar manner as described above, the C ₆₀ to the surface of the ITO / Fc / Ru film of the light-absorbing layer A (Ru film) was coated by vacuum deposition, which is an electron transporting layer N. Furthermore, to obtain a photoelectric element 50 ₄ aluminum as the second electrode layer 52 on the electron transport layer N was deposited by manufacturing methods described above. As a result of the photocurrent measurement, a similar photoelectric conversion effect was obtained.

[Example 9]
Next, a photoelectric device 50 ₄ shown in FIG. 12 (4) shows the case of including a step of forming the electron-transporting layer N by the liquid crystal system.
A conductive liquid crystal hexyloxyphenyl-hexyloxybiphenyloxadiazole was disposed on the surface of the light absorption layer A (Ru film) of the ITO / Fc / Ru film prepared in the same manner as described above, and this was used as an electron. This is the transport layer N. Furthermore, to obtain a photoelectric element 50 ₄ by placing a platinum plate on the electron transport layer N as a second electrode layer 52. As a result of the photocurrent measurement, a similar photoelectric conversion effect was obtained.

[Example 10]
(Preparation of tin oxide transparent electrode)
The case where SnO ₂ (tin oxide) is used as the transparent electrode will be described. Here, belonging to the types of the photoelectric element 50 ₄ shown in FIG. 12 (4), shows a method for forming a two-component adsorption system +1 component surface decoration system. Here, the electron transporting layer N ₄ is made of fullerene carboxylic acid (C ₆₀ C (COOH) ₂ ) (d).

First, a 15 wt% aqueous colloidal suspension (containing potassium ions as a stabilizer) of SnO ₂ fine particles (安定 15 nm) is cast on the ITO electrode washed by the above method, and dried on a hot plate. The dried substrate is annealed at 400 ° C. for 1 hour using an electric furnace to obtain a SnO ₂ transparent electrode.

(Immobilization of fullerene carboxylic acid C ₆₀ C (COOH) ₂ )
Next, 3-aminopropyltriethoxysilane (3-aminopropyltriethoxysilane) is immobilized on the SnO ₂ transparent electrode by the same method as the above-described silane coupling reaction on the ITO electrode. The substrate was washed with a toluene and acetone solution and then immersed in a bromobenzene solution containing 1 mM C ₆₀ C (COOH) ₂ and 1H-benzotriazol-1-ol (1H-benzotriazol-1-o1), respectively. Then, after cooling to 0 ° C., dicyclohexylcarbodiimide is added, and the mixture is fixed at room temperature with stirring. The amount of C ₆₀ C (COOH) ₂ immobilized can be arbitrarily controlled by changing the immersion time. The immobilization of C ₆₀ C (COOH) ₂ can also be performed directly on the SnO ₂ transparent electrode substrate without using a silane coupling agent.

As described above, although not described, the SnO ₂ transparent electrode (the second electrode layer 52) is decorated with the fullerene carboxylic acid (レ) on the surface of the electron transport layer N _4. were sequentially prepared ₂ / C60 / Ru / Fc film, to obtain a photoelectric element 50 ₄ gold was vapor-deposited as a counter electrode (first electrode layer 51 _4). As a result of the photocurrent measurement, a similar photoelectric conversion effect was obtained.
Although not described, a PEDOT / PSS layer (PEDOT / PSS (c)) having a high hole transporting ability is added by spin coating or alternate adsorption instead of the Fc layer (ferrocene-containing polymer (b)). Then, a structure in which the hole transport layer P is formed is also possible. As shown in the type of FIG. 12 (14), PEDOT / PSS is provided between the Fc layer (electron donating layer E) and an electrode (first electrode layer 51) such as ITO or gold or platinum serving as a positive electrode. It is also possible to increase the hole transport efficiency by inserting a layer.

It is a conceptual diagram which shows the manufacturing principle of an alternate adsorption film. It is a conceptual diagram which shows the manufacturing process of an alternate adsorption film. It is a conceptual diagram which shows the other structure of an alternate adsorption film. It is a schematic diagram which shows the energy level of the photoelectric element of this invention. It is a cross section showing an example of the photoelectric conversion device by the present invention. FIG. 4 is a schematic sectional view showing another example of the photoelectric conversion device according to the present invention. FIG. 3 is a schematic diagram showing a structure of a photoelectric conversion device having a structure in which a grid wiring 29 is formed under a transparent conductive film 22. FIG. 7A is a sectional view, and FIG. 7B is a top view. The potential of each functional layer of the photoelectric functional polymer thin film is shown. Photocurrent measurement results. Photocurrent measurement results. FIG. 4 is a schematic sectional view showing another example of the photoelectric conversion device according to the present invention. It is a conceptual diagram which shows the type when at least a light absorption layer is formed by the alternate adsorption method among the photoelectric elements in this invention. It is a figure which shows the electronic functional group of each layer which comprises the photoelectric element in this invention exemplarily.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Substrate 2 1st water tank 3 2nd water tank 4 Cationic polymer 5 Electron-donating group 6 Anionic polymer 7 Photosensitizing group 10 Photoelectric element 11 1st electrode layer 12 Hole transport layer 13 Light absorption layer 14 Electron Transport layer 15 Second electrode layer 21 Glass substrate 22 Transparent conductive film 23 Electron donating layer 24 Light absorbing layer 25 Electron accepting layer 26 Electrode 27 Terminal contact 28 Conducting wire 29 Grid line 31 Anionic polymer 32 Cationic polymer 50 (50 ₁ , 50 _2, ...) the photoelectric element 51 (51 _1, 51 _2, ...) the first electrode layer 52 (52 _1, 52 _2, ...) second electrode layer 60 (60 _1, 60 _2, ...) thin layer P (P ₁ , P ₂ ,...) Hole transport layer E (E ₁ , E ₂ ,...) Electron donating layer A (A ₁ , A ₂ ,...) Light absorbing layer N (N ₁ , N ₂ ,...) Electron transport layer

Claims (21)

  A multi-layered thin film having at least one pair of an alternating adsorption film of a cationic polymer and / or an anionic polymer having a photosensitizing group introduced into at least a part thereof, and the highest occupied electron of each layer of the multilayer thin film including the alternating adsorption film A polymer thin film characterized in that the level or the lowest vacancy level has a gradient.   A photoelectric device comprising a first electrode layer, a hole transporting (electron donating) layer, a light absorbing layer, an electron transporting (electron accepting) layer, and a second electrode layer, wherein the hole transporting layer has an electron donating property. A cationic polymer having an introduced group and an anionic polymer, or an alternately adsorbed film of an anionic polymer and a cationic polymer having introduced an electron donating group, wherein the alternately adsorbed film has at least one set of the cationic polymer layer. The first electrode layer, the hole transport (electron donating) layer, and the highest occupied electron level of the light absorbing layer are close to the first electrode layer. The photoelectric element characterized in that the photoelectric element is improved according to the following.   A photoelectric device comprising a first electrode layer, a hole transporting (electron donating) layer, a light absorbing layer, an electron transporting (electron accepting) layer, and a second electrode layer, wherein the electron transporting layer has an electron accepting group. Comprising an alternately adsorbed film of a cation polymer and an anion polymer having introduced thereinto, or an anion polymer and a cation polymer having introduced an electron accepting group, wherein the alternately adsorbed film comprises at least one pair of the cation polymer and the anion. It has a multilayer structure composed of a polymer, and the lowest vacancy levels of the light absorbing layer, the electron transporting (electron accepting) layer, and the second electrode layer decrease as approaching the second electrode layer. An optoelectronic device comprising: A photoelectric device comprising a first electrode layer, a hole transporting (electron donating) layer, a light absorbing layer, an electron transporting (electron accepting) layer, and a second electrode layer, wherein the hole transporting layer has an electron donating property. A cationic polymer having an introduced group and an anionic polymer, or an alternately adsorbed film of an anionic polymer having introduced an electron donating group and a cationic polymer, and wherein the electron transporting layer has a high cation having an electron accepting group. A layer comprising an alternately adsorbed film of a molecule and an anionic polymer, or an anionic polymer and a cationic polymer into which an electron-accepting group is introduced, wherein at least one of the alternately adsorbed films forming the hole transport layer and the electron transport layer is formed. The first electrode layer, the hole transport (electron donating) layer, and the highest occupied electron level of the light absorbing layer are the multilayer structure composed of the set of the cationic polymer and the anionic polymer. Approach the first electrode layer Accordingly, the lowest vacancy level of the light absorbing layer, the electron transporting (electron accepting) layer, and the second electrode layer decreases as approaching the second electrode layer. element.   An optoelectronic device comprising a first electrode layer, a light absorbing layer, an electron transporting (electron accepting) layer, and a second electrode layer, wherein the electron transporting layer has a cationic polymer into which an electron accepting group is introduced and an anion high. Molecule, or an alternately adsorbed film of an anion polymer and a cation polymer into which an electron accepting group is introduced, wherein the alternately adsorbed film has a multilayer structure including at least one set of the cation polymer and the anion polymer, A photoelectric device, wherein the lowest vacancy levels of the light absorbing layer, the electron transporting (electron accepting) layer, and the second electrode layer decrease as approaching the second electrode layer.   An optoelectronic device comprising a first electrode layer, a hole transport (electron donating) layer, a light absorbing layer, and a second electrode layer, wherein the hole transport layer comprises a cationic polymer having an electron donating group introduced therein. An anionic polymer, or an alternately adsorbed film of an anionic polymer and a cationic polymer into which an electron-donating group is introduced, wherein the alternately adsorbed film has a multilayer structure comprising at least one layer of the cationic polymer and the anionic polymer. And the highest occupied electron levels of the first electrode layer, the hole transporting (electron donating) layer, and the light absorbing layer are improved as approaching the first electrode layer. Photoelectric element.   The photoelectric device according to any one of claims 2 to 6, wherein the light-absorbing layer comprises a cationic polymer and an anionic polymer having a photosensitized group introduced therein, or an anionic polymer and a cationic polymer having a photosensitized group introduced therein. Wherein the alternating adsorption film has a multilayer structure comprising at least one pair of the cationic polymer and the anionic polymer.   The photoelectric device according to any one of claims 2, 3, 4, 6, and 7, wherein the first electrode layer also serves as a hole transport layer.   The photoelectric device according to any one of claims 2, 3, 4, 5, and 7, wherein the second electrode layer also serves as an electron transport layer.   The photoelectric device according to claim 7, wherein the photosensitizing group comprises a ruthenium complex compound.   The photoelectric device according to any one of claims 2, 3, 4, 6, 7, 8, 9, and 10, wherein the electron donating group comprises a thiophene compound or a ferrocene compound.   The photoelectric device according to any one of claims 3, 4, 5, 7, 8, 9, 10, and 11, wherein the electron accepting group comprises a fullerene derivative. A photoelectric element having a thin film layer and a first electrode layer and a second electrode layer disposed on both surfaces of the thin film layer,
The thin film layer,
A light absorbing layer that absorbs light energy,
A first electron donating group that donates an electron, thereby transferring a hole generated by the light absorption to the first electrode layer;
An electron transporting layer that transfers electrons generated by the light absorption to the second electrode layer by receiving an electron accepting group,
The light absorbing layer,
An optoelectronic device, wherein a polymer having a photosensitizing group introduced therein is formed by lamination by an alternate adsorption method. A photoelectric element having a thin film layer and a first electrode layer and a second electrode layer disposed on both surfaces of the thin film layer,
The thin film layer,
A light absorbing layer that absorbs light energy,
A hole transport layer that transfers holes generated by the light absorption to the first electrode layer by the first electron donating group donating an electron,
The light absorbing layer,
An optoelectronic device, wherein a polymer having a photosensitizing group introduced therein is formed by lamination by an alternate adsorption method. A photoelectric element having a thin film layer and a first electrode layer and a second electrode layer disposed on both surfaces of the thin film layer,
The thin film layer,
A light absorbing layer that absorbs light energy,
An electron transport layer that delivers electrons generated by the light absorption to the second electrode layer by receiving the electrons by an electron accepting group,
The light absorbing layer,
An optoelectronic device, wherein a polymer having a photosensitizing group introduced therein is formed by lamination by an alternate adsorption method. The photoelectric device according to any one of claims 13 and 14,
The hole transport layer,
A photoelectric device, wherein the polymer having the first electron-donating group introduced therein is formed by stacking by an alternate adsorption method. The photoelectric device according to any one of claims 13, 15, and 16,
The electron transport layer,
A photoelectric device, wherein the polymer having the electron-accepting group introduced therein is formed by lamination by an alternate adsorption method. The photoelectric device according to any one of claims 13, 14, 16, and 17,
An electron donating layer having a second electron donating group having a higher electron donating property than the first electron donating group is provided at an interface between the hole transport layer and the light absorbing layer. Photoelectric element. The photoelectric device according to claim 18,
The photoelectric element, wherein the electron donating layer is formed by laminating polymers into which the second electron donating groups are introduced by an alternate adsorption method. The photoelectric device according to any one of claims 13 to 19,
The light-absorbing layer has a thickness of 1 nm to 30 nm.   A solar cell using the photoelectric device according to any one of claims 2 to 20, having a function of converting light energy into electric energy and extracting it as electric power.