JP6028238B2 - Semiconductor fine particle film, diode, photoelectric conversion element, and manufacturing method thereof - Google Patents

Description

The present invention relates to an improvement of a semiconductor fine particle film using silicon fine particles, a diode and a photoelectric conversion element using the same, and a method for producing them.

As a conventional silicon photoelectric conversion element, a silicon amorphous photoelectric conversion element formed on the surface of a glass substrate using a plasma CVD method, a silicon crystal or a polysilicon crystal is cut and processed into a plate shape, and then impurities are diffused. A silicon crystal photoelectric conversion element or the like is known (see, for example, Patent Document 1).

However, since the conventional silicon amorphous photoelectric conversion element uses an expensive vacuum device, there is a drawback in that the manufacturing cost increases. In addition, the silicon crystal photoelectric conversion element has a drawback in that the manufacturing cost increases because a large amount of high-purity silicon crystal or polysilicon crystal is used.

In view of the above problems, the present inventor has provided a large-area photoelectric conversion element and a method for manufacturing the same that can significantly reduce costs compared to conventional amorphous photoelectric conversion elements and silicon crystal photoelectric conversion elements while using silicon. As an object, n-type silicon fine particles covered with an organic film containing a first reactive functional group covalently bonded to the surface and n-type covered with an organic film containing a second reactive functional group covalently bonded to the surface A step of mixing silicon fine particles in an organic solvent to form a paste, and applying the paste to the surface of the substrate; an organic film containing p-type silicon fine particles covered with an organic film; and a second reactive functional group covalently bonded to the surface The p-type silicon fine particles covered in step 1 are mixed in an organic solvent to produce a paste, the step of applying to the substrate surface, and the step of curing n. p-type silicon fine particle layer on the silicon particle layer and the surface is covered with an organic thin film covalently bonded proposed a photoelectric conversion device and a manufacturing method thereof are laminated (e.g., see Patent Document 2).

JP-A-10-247629 JP 2007-173516 A

However, in the photoelectric conversion element described in Patent Document 2 and the method for manufacturing the photoelectric conversion element, when a diode having excellent junction characteristics is to be manufactured, when p-type or n-type silicon fine particles having a particle size of 10 nm are used, the atoms constituting the fine particles as the number is reduced to about ¹⁰⁶ or so, there is a case where control of the impurity atom concentration is difficult. That is, in order to reduce the impurity atom concentration in the p-type or n-type silicon fine particle layer to about 10 ¹² to 10 ¹⁷ cm ⁻³ , the impurity atoms (boron, phosphorus, and silicon atoms at a ratio of 1 per 10 ⁶ to 10 ¹¹ silicon atoms. In particular, when p-type or n-type silicon fine particles having a particle size of about 10 nm are used, the number of impurity atoms per fine particle is 1 or less. Moreover, it becomes very difficult to control the impurity atom concentration.

The present invention has been made in view of such circumstances, and does not impair the original function of silicon fine particles, has a uniform thickness at the particle size level, can be manufactured at low cost, and can easily control the impurity atom concentration. An object of the present invention is to provide an n-type silicon fine particle film, a diode and a photoelectric conversion element having the same, and a cheap and simple manufacturing method thereof.

The first aspect of the present invention that meets the above-described object is that two or more types of silicon fine particles having different impurity atom concentrations covered with a monomolecular film have an average impurity atom concentration of 10 ¹⁰ to 10 ²⁰ cm ^−3. The film-like structure is formed by the two or more types of silicon fine particles that are uniformly mixed and the two or more types of silicon fine particles are mixed with each other through the monomolecular film. The above problem is solved by providing a semiconductor fine particle film.

In the present invention, the term “silicon fine particles” is used as a general term when referring to two or more kinds of mixed silicon fine particles as a whole or when referring to one specific fine particle regardless of the impurity atom concentration or the like.

In the semiconductor fine particle film according to the first aspect of the present invention, the bonding of the two or more types of silicon fine particles bonded to each other via the monomolecular film is preferably molecular crosslinking .

In the semiconductor fine particle film according to the first aspect of the present invention, the two or more types of silicon fine particles may be a combination of pure silicon fine particles and p-type silicon fine particles or n-type silicon fine particles.

In the semiconductor fine particle film according to the first aspect of the present invention, the mixture of the two or more types of silicon fine particles may contain silicon fine particles having different particle diameters.

In the semiconductor fine particle film according to the first aspect of the present invention, the silicon fine particles preferably have a particle diameter of 10 to 5 μm.

In the semiconductor fine particle film according to the first aspect of the present invention, the surface of the silicon fine particle has a first reactive functional group and is chemically bonded via a Si—O— bond, A first coating covering a part, or a second reactive functional group that reacts with the first functional group to form a chemical bond, and is chemically bonded via a Si-O- bond; A second film covering at least a part of the surface is formed, and the first reactive functional group and the second reactive functional group existing on different silicon fine particles react with each other. The molecular bridge may be formed by chemical bonding.

In the above case, the chemical bond formed by the reaction between the first reactive functional group and the second reactive functional group was formed by the reaction between an amino group or imino group and an epoxy group. Any of an N—CH ₂ CH (OH) bond and an NH—CONH bond formed by a reaction between an amino group or an imino group and an isocyanate group may be used.

In the semiconductor fine particle film according to the first aspect of the present invention, the surface of the silicon fine particle has a fourth reactive functional group, chemically bonded via a Si—O— bond, and at least the surface of the silicon fine particle film. A fourth coating film partially covering the fourth reactive functional group of the fourth coating chemically bonded to one of the silicon microparticles, and silicon microparticles other than the one silicon microparticle Through a cross-linking agent having a plurality of cross-linking reactive groups that form a chemical bond by reacting with the reactive functional group by heat and the fourth reactive functional group of the fourth film chemically bonded to And may be formed by chemical bonding.

In the above case, the chemical bond formed by the reaction between the fourth reactive functional group and the crosslinking reactive group is an N-CH ₂ CH (formed by the reaction between an amino group or imino group and an epoxy group. OH) bond and NH-CONH bond formed by reaction of amino group or imino group with isocyanate group.

According to a second aspect of the present invention, there is provided a method for producing a semiconductor fine particle film according to the first aspect of the present invention, the first film having a first reactive functional group and a halosilyl group or an alkoxysilyl group. Two or more kinds of silicon fine particles having different impurity atom concentrations are used as compounds, and the average concentration of impurity atoms is 10 ¹⁰ to 10 ²⁰ cm ⁻³ (wherein the preferable impurity concentration of the coating film is 10 ¹¹ to 10 ¹⁸ / cm ^3. More preferably, it is about 10 ¹² to 10 ¹⁷ / cm ³ , but it may be adjusted as necessary. The same shall apply hereinafter)), and the halosilyl group or A Si—O— bond is formed between the alkoxysilyl group and the surface functional group of the silicon fine particle, and the first film formed by the first film compound has a small surface. A first reactive silicon fine particle mixture partially covered, a second reactive functional group that reacts with the first reactive functional group by heat to form a chemical bond, and A second film compound having a halosilyl group or an alkoxysilyl group is brought into contact with the silicon fine particle mixture to form a Si—O— bond between the halosilyl group or alkoxysilyl group and the surface functional group of the silicon fine particle. Manufacturing a second reactive silicon fine particle mixture having at least part of its surface covered with a second film formed by the second film compound, the first reactive silicon fine particle mixture, and the first A step of producing a paste by mixing the reactive silicon fine particle mixture of 2 in an organic solvent, and a paste containing the first and second reactive silicon fine particle mixture A step of applying to the surface of the base material; and a step of forming a chemical bond by a reaction between the first reactive functional group and the second reactive functional group, and curing the coating film of the paste. The above-mentioned problems are solved by providing a method for producing a semiconductor fine particle film characterized by the above.

In the method for producing a semiconductor fine particle film according to the second aspect of the present invention, after the first and second coatings are formed, the first and second reactive silicon fine particle mixtures are washed with a solvent, and the excess It is preferable to further have a step of removing the first and second film compounds.

According to a third aspect of the present invention, there is provided a method for producing a semiconductor fine particle film according to the first aspect of the present invention, the first film having a first reactive functional group and a halosilyl group or alkoxysilyl group, respectively. The compound is brought into contact with each of two or more kinds of silicon fine particles having different impurity atom concentrations to form Si—O— bonds between the halosilyl group or alkoxysilyl group and the surface functional groups of the silicon fine particles, and A step of producing two or more kinds of first reactive silicon fine particles having at least a part of the surface covered with a first film formed by one film compound, and the first reactive functional group and heat. A second reactive functional group that reacts to form a chemical bond and a second film compound each having a halosilyl group or an alkoxysilyl group are added to each of the two or more types of silicon fine particles. At least one surface of the second coating film formed by the second film compound. The Si—O— bond is formed between the halosilyl group or alkoxysilyl group and the surface functional group of the silicon fine particles. A step of producing two or more types of second reactive silicon fine particles covered with a portion, the two or more types of first reactive silicon fine particles and the two or more types of second reactive silicon fine particles, A step of producing a paste containing a mixture of reactive silicon fine particles by uniformly mixing in an organic solvent so that the average concentration of impurity atoms is 10 ¹⁰ to 10 ²⁰ cm ^−3, and applying the paste to the substrate surface And a step of forming a chemical bond by a reaction between the first reactive functional group and the second reactive functional group and curing the coating film of the paste. The above-mentioned problems are solved by providing a method for producing a semiconductor fine particle film.

In the method for producing a semiconductor fine particle film according to the third aspect of the present invention, after the first and second coatings are formed, the two or more types of the first and second reactive silicon fine particles are respectively washed with a solvent. It is preferable that the method further includes a step of removing excess first and second film compounds.

In the method for producing a semiconductor fine particle film according to the second and third aspects of the present invention, one or both of the first and second reactive functional groups are previously formed on the surface of the base material before applying the paste. A third reactive functional group to be reacted and a third film compound each having a halosilyl group or an alkoxysilyl group are brought into contact with each other, and Si—O is interposed between the halosilyl group or alkoxysilyl group and the surface functional group of the substrate. -It is preferable to further have the process of manufacturing the reactive base material in which the bond was formed and at least one part of the surface was covered with the 3rd film which the said 3rd film | membrane compound forms.

In the method for producing a semiconductor fine particle film according to the second and third aspects of the present invention, after the formation of the third film, the surface of the reactive substrate is washed with a solvent, and the excess third film compound It is preferable to further include a step of removing.

A fourth aspect of the present invention is a method for producing a semiconductor fine particle film according to the first aspect of the present invention , wherein the fourth film has a fourth reactive functional group and a halosilyl group or an alkoxysilyl group, respectively. The compound is brought into contact with a silicon fine particle mixture in which two or more kinds of silicon fine particles having different impurity atom concentrations are uniformly mixed so that the average concentration of impurity atoms is 10 ¹⁰ to 10 ²⁰ cm ^−3, and the halosilyl group or alkoxy Si—O— bonds are formed between the silyl group, the pure silicon fine particles, and the surface functional groups of the p-type or n-type silicon fine particles, and at least a part of the surface is covered with the coating formed by the fourth film compound. Reacting the fourth reactive silicon fine particle mixture, the fourth reactive silicon fine particle mixture, and the fourth reactive functional group with heat. A step of producing a paste by mixing a crosslinking agent having a plurality of crosslinking reactive groups that form a chemical bond in an organic solvent, and a paste containing the fourth reactive silicon fine particle mixture and the crosslinking agent as a base material A semiconductor fine particle comprising: a step of applying to a surface; and a step of forming a chemical bond by a reaction between the fourth reactive functional group and the cross-linking reactive group to cure the paste coating film. The above-mentioned problems are solved by providing a method for producing a film.

In the method for producing a semiconductor fine particle film according to the fourth aspect of the present invention, after the formation of the fourth film, the fourth reactive silicon fine particle mixture is washed with a solvent, and the excess fourth film compound is removed. It is preferable to further have the process of removing.

A fifth aspect of the present invention is a method for manufacturing a semiconductor fine particle film according to the first aspect of the present invention, wherein the fourth film has a fourth reactive functional group and a halosilyl group or an alkoxysilyl group, respectively. A compound is brought into contact with each of two or more kinds of silicon fine particles having different impurity atom concentrations, and Si-- between the halosilyl group or alkoxysilyl group, the pure silicon fine particles, and the surface functional groups of the p-type or n-type silicon fine particles. A step of producing two or more types of fourth reactive silicon fine particles in which at least part of the surface is covered with a film formed by the fourth film compound by forming an O-bond; 4 reactive silicon fine particles and a cross-linking agent having a plurality of cross-linking reactive groups that react with the fourth reactive functional group by heat to form a chemical bond are mixed in an organic solvent. A chemical bond is formed by the reaction of the fourth reactive functional group and the crosslinking reactive group, and the coating film of the paste is cured. The above-mentioned problems are solved by providing a method for producing a semiconductor fine particle film characterized by comprising a step of:

In the method for manufacturing a semiconductor fine particle film according to the fifth aspect of the present invention, after the formation of the fourth film, the two or more types of fourth reactive silicon fine particles are washed with a solvent, and the extra fourth It is preferable to further include a step of removing the membrane compound.

In the method for producing a semiconductor fine particle film according to the fourth and fifth aspects of the present invention, the halosilyl group or alkoxysilyl group is obtained by bringing the fourth film compound into contact with the surface of the substrate before applying the paste in advance. A reactive base material in which at least a part of the surface is covered with a fourth film formed by the fourth film compound by forming a Si—O— bond between a group and a surface functional group of the base material It is preferable to further have a manufacturing step.

In the method for producing a semiconductor fine particle film according to the fourth and fifth aspects of the present invention, after forming the fourth film on the surface of the reactive substrate, the surface of the reactive substrate is washed with a solvent, It is preferable to further include a step of removing excess unreacted fourth film compound.

In the method for producing a semiconductor fine particle film according to the second and third aspects of the present invention, the reaction between the first reactive functional group and the second reactive functional group, or the first reactivity. A chemical bond formed by the reaction of the functional group of the second reactive functional group with an N-CH ₂ CH (OH) bond formed by the reaction of an amino group or imino group with an epoxy group, and It may be any NH—CONH bond formed by the reaction of an amino group or imino group with an isocyanate group.

In the method for producing a semiconductor fine particle film according to the fourth and fifth aspects of the present invention, the chemical bond formed by the reaction between the fourth reactive functional group and the crosslinking reactive group is an amino group or an imino group. N—CH ₂ CH (OH) bond formed by the reaction of the epoxy group with the epoxy group and NH—CONH bond formed by the reaction of the amino group or imino group with the isocyanate group may be used.

In the method for producing a semiconductor fine particle film according to the second to fifth aspects of the present invention, the two or more types of silicon fine particles are a combination of pure silicon fine particles and p-type silicon fine particles or n-type silicon fine particles, or p-type. A combination of silicon fine particles and n-type silicon fine particles may be used.

In the method for producing a semiconductor fine particle film according to the second to fifth aspects of the present invention , the silicon fine particles preferably have a particle size of 10 nm to 5 μm.

In the method for producing a semiconductor fine particle film according to the second to fifth aspects of the present invention, the mixture of two or more types of silicon fine particles may contain silicon fine particles having different particle diameters.

A sixth aspect of the present invention was coated with two or more different n-type silicon microparticles or coated pure silicon particles and a monomolecular film with a monomolecular film, impurity atom concentration, which is coated with a monomolecular film n -type silicon particles, the average concentration of the impurity atoms are uniformly mixed such that ¹⁰ 10 ~10 ²⁰ cm ^-3, mixed with state, the monomolecular film laminated membrane-like structures attached at a molecular cross-linked to each other via And an n-type semiconductor layer coated with a monomolecular film and two or more types of p-type silicon fine particles having different impurity atom concentrations, or a pure silicon fine particle coated with a monomolecular film and a p-type coated with a monomolecular film A laminated film in which silicon fine particles are uniformly mixed so as to have an average concentration of impurity atoms of 10 ¹⁰ to 10 ²⁰ cm ^−3, and in a mixed state, are bonded to each other through molecular bridges via the monomolecular film. The above problem is solved by providing a diode characterized in that a p-type semiconductor layer having a planar structure is laminated on a base material.

In the diode according to the sixth aspect of the present invention, it is preferable that the two or more types of silicon fine particles have a particle size of 10 nm to 5 μm.

In the diode according to the sixth aspect of the present invention, the mixture of two or more kinds of silicon fine particles may contain silicon fine particles having different particle diameters.

In the diode according to the sixth aspect of the present invention, the molecular bridge includes a first reactive functional group of the first coating chemically bonded to one of the silicon fine particles, and silicon fine particles other than the silicon fine particles. It may be formed by reacting and chemically bonding with a second reactive functional group that reacts with the first functional group of the second chemically bonded film to form a chemical bond.

In the above case, the chemical bond formed by the reaction between the first reactive functional group and the second reactive functional group was formed by the reaction between an amino group or imino group and an epoxy group. Any of an N—CH ₂ CH (OH) bond and an NH—CONH bond formed by a reaction between an amino group or an imino group and an isocyanate group may be used.

In the diode according to the sixth aspect of the present invention, the molecular cross-linking is a reactive third functional group of a coating chemically bonded to one of two or more types of silicon fine particles, and the one or more types of two or more types of silicon. A cross-linking agent having the reactive functional group of the coating chemically bonded to two or more types of silicon fine particles other than the fine particles, and a plurality of cross-linking reactive groups that react with the reactive functional group by heat to form a chemical bond. It may be formed by chemical bonding via.

In the above case, the chemical bond formed by the reaction between the third reactive functional group and the crosslinking reactive group is an N-CH ₂ CH (formed by the reaction between an amino group or imino group and an epoxy group. OH) bond and NH-CONH bond formed by reaction of amino group or imino group with isocyanate group.

A seventh aspect of the present invention solves the above problem by providing a photoelectric conversion element including a diode according to the sixth aspect of the present invention.

In the photoelectric conversion element according to the seventh aspect of the present invention, the photoelectric conversion element may be a solar cell or a photosensor.

According to an eighth aspect of the present invention, an average concentration of impurity atoms is 10 ¹⁰ to 10 ²⁰ cm ⁻³ on a transparent substrate by any one of the methods according to the second to fifth aspects of the present invention. A step of forming an n-type semiconductor layer having a laminated film structure in which a plurality of uniformly mixed pure silicon fine particles and a plurality of n-type silicon fine particles are chemically bonded to each other through molecular crosslinking; A plurality of pure silicon fine particles uniformly mixed on the n-type silicon fine particle layer so as to have an average concentration of impurity atoms of 10 ¹⁰ to 10 ²⁰ cm ⁻³ by any one of the methods according to the fifth aspect; And a step of forming a p-type semiconductor layer having a laminated film structure in which a plurality of p-type silicon fine particles are chemically bonded to each other through molecular crosslinking. The above-mentioned problem is solved more.

According to a ninth aspect of the present invention, there is provided a method for manufacturing a photoelectric conversion element including the method for manufacturing a diode according to the eighth aspect of the present invention.

In the method for manufacturing a photoelectric conversion element according to the ninth aspect of the present invention, the photoelectric conversion element may be a solar cell or a photosensor.

As described above, according to the present invention, by using a combination of a plurality of silicon fine particles having different impurity concentrations, the semiconductor fine particle film capable of easily controlling the impurity atom concentration and film thickness and excellent bonding characteristics using the same. A high-performance photoelectric conversion element, a semiconductor fine particle film that can be manufactured inexpensively and simply, and a method for manufacturing a photoelectric conversion element using the same are provided. Furthermore, the manufacture of the semiconductor fine particle film and the photoelectric conversion element of the present invention does not require expensive vacuum equipment, and can be easily manufactured from a fine shape to a large area using a wet method.

It is explanatory drawing which represented typically the cross-sectional structure of the semiconductor fine particle film which concerns on 1st embodiment of this invention. In the manufacturing method of the semiconductor fine particle film, in order to explain the process of manufacturing the epoxidized silicon fine particles, it is a schematic diagram enlarged to the molecular level, (a) is a cross-sectional structure of the silicon fine particles before the reaction, (b) is an epoxy Each represents a cross-sectional structure of an epoxidized silicon fine particle on which a monomolecular film containing a group is formed. It is explanatory drawing which represented typically the cross-sectional structure of the semiconductor fine particle film which concerns on 2nd embodiment of this invention. It is explanatory drawing which represented typically the cross-section of the solar cell which concerns on 3rd embodiment of this invention.

In the semiconductor fine particle film of the present invention, two or more types of silicon fine particles having different impurity atom concentrations are uniformly mixed so that the average concentration of impurity atoms is 10 ¹⁰ to 10 ²⁰ cm ^−3. A chemically bonded film-like structure is formed. Hereinafter, semiconductor fine particle films according to the first to fourth embodiments, which are different in the mode of formation of the molecular bridge and the manufacturing method, will be described with reference to the drawings. In each of the following embodiments, a case will be described in which pure silicon fine particles and n-type silicon fine particles are used in combination as two or more types of silicon fine particles having different impurity atom concentrations.

The method for producing a semiconductor fine particle film includes a method in which a reactive silicon fine particle mixture is pasted, applied onto a substrate, and a coating film is cured to laminate a plurality of layers at once, and a reactive silicon fine particle mixture dispersion It is roughly classified into a method of laminating one layer at a time by applying and bonding to the surface of the substrate and washing away and removing the excess reactive silicon fine particle mixture. Further, from the viewpoint of a method for forming molecular crosslinks, a method using two kinds of coatings including one of two reactive functional groups to be paired, one reactive functional group, and two or more crosslinkable reactive groups It is roughly classified into a method using a combination with a crosslinking agent.

As shown in FIGS. 1 and 2, in the n-type silicon fine particle film (an example of a semiconductor fine particle film) 10 according to the first embodiment of the present invention, the surface of the silicon fine particle has an epoxy group (first A monomolecular film of an alkoxysilane compound having an epoxy group, which is chemically bonded via an Si—O— bond and covers at least a part of the surface thereof (first example of a reactive functional group). 16), or an amino group (an example of a second reactive functional group) that reacts with an epoxy group to form a bond, and is chemically bonded via a Si—O— bond. A monomolecular film (an example of a second film) of an alkoxysilane compound having an amino group (not shown) is formed so as to cover at least a part of the film. Among these silicon fine particles, there are epoxy groups present on the epoxidized pure silicon fine particles 11 and the epoxidized n-type silicon fine particles 11a and amino groups present on the aminated silicon fine particles 12 and the aminated n-type silicon fine particles 12a. By reacting and chemically bonding, an N—CH ₂ CH (OH) bond (an example of molecular cross-linking) is formed, and a film-like structure in which silicon fine particles are chemically bonded to each other through this bond is formed. Yes.

The surface of the reactive base material 13 on which the n-type silicon fine particle film 10 is formed has an epoxy group or an amino group (an example of a third reactive functional group), and chemically reacts via Si—O— bonds. A monomolecular film (an example of a third coating film) of an alkoxysilane compound having an epoxy group or an amino group, which is bonded and covers at least a part of the surface thereof, is formed, and epoxidized pure silicon fine particles 11 and epoxidized N—CH ₂ CH (OH) bond (an example of molecular cross-linking) between an epoxy group present on the n-type silicon fine particle 11a or an amino group present on the aminated silicon fine particle 12 and the aminated n-type silicon fine particle 12a ) And the n-type silicon fine particle film 10 and the base material are firmly bonded.

The n-type silicon fine particle film 10 is manufactured by a method including the following steps [1] to [6].
[1] Pure silicon fine particles and n-type silicon in which an alkoxysilane compound having an epoxy group (an example of a first film compound) is uniformly mixed so that an average concentration of impurity atoms is 10 ¹⁰ to 10 ²⁰ cm ⁻³ Contact with a mixture of fine particles (an example of a silicon fine particle mixture: hereinafter, sometimes simply abbreviated as “silicon fine particle mixture”), and an alkoxysilyl group and a hydroxyl group on the surface of the silicon fine particle (an example of a surface functional group) 15 A mixture of epoxidized pure silicon fine particles 11 and epoxidized n-type silicon fine particles 11a in which at least part of the surface is covered with a monomolecular film 16 of an alkoxysilane compound having an epoxy group, with Si—O— bonds formed between them. (Example of first reactive silicon fine particle mixture: hereinafter referred to as “epoxidized silicon fine particle mixture”) (2) A step of producing an alkoxysilane compound having an amino group (an example of the second film compound) is brought into contact with the silicon fine particle mixture, and Si between the alkoxysilyl group and the hydroxyl group 15 on the surface of the silicon fine particle is obtained. A mixture of aminated pure silicon fine particles 12 and aminated n-type silicon fine particles 12a (second reaction) in which —O— bonds are formed and at least a part of the surface is covered with a monomolecular film of an alkoxysilane compound having an amino group Example of reactive silicon fine particle mixture: hereinafter referred to as “aminated silicon fine particle mixture” in some cases.) [3] Third reactive functional group that reacts with epoxy group or amino group on substrate surface An alkoxysilane compound (an example of a third film compound) having a contact is brought into contact with Si between the alkoxysilyl group and the surface functional group of the substrate. Step [4] Epoxidized silicon for forming a reactive substrate 13 in which —O— bond is formed and at least a part of the surface is covered with a monomolecular film of the third film compound (an example of the third film) A step of producing a paste by mixing the fine particle mixture and the aminated silicon fine particle mixture in an organic solvent [5] A step of applying a paste containing the epoxidized silicon fine particle mixture and the aminated silicon fine particle mixture to the surface of the reactive substrate 13 [6] A step of forming an N—CH ₂ CH (OH) bond by a reaction between an epoxy group and an amino group, and curing the coating film of the paste.

Hereinafter, each process will be described in more detail.
[1] Production of Epoxidized Silicon Fine Particle Mixture As shown in FIG. 2, the epoxidized silicon fine particle mixture undergoes a condensation reaction between an alkoxysilane compound containing an epoxy group, an alkoxysilyl group, and a hydroxyl group 15 on the surface of the silicon fine particle. It is produced by bringing silicon fine particles into contact with an alkoxysilane compound in a reaction solution containing a condensation catalyst for promotion and a non-aqueous organic solvent.

The particle size of silicon fine particles (pure silicon fine particles and n-type silicon fine particles) used for the production of the epoxidized silicon fine particle mixture is preferably 10 to 5 μm. When the particle diameter of the silicon fine particles is less than 10 nm, the volume fraction of the monomolecular film having an epoxy group or amino group in the n-type silicon fine particle film 10 becomes too large, and the electrical characteristics may be deteriorated. On the other hand, if the particle size of the silicon fine particles exceeds 5 μm, the porosity in the n-type silicon fine particle film 10 increases, so that there is a possibility that the electrical characteristics also deteriorate. In addition, when a fine silicon fine particle pattern for a device is formed by printing, the cut of the pattern becomes worse.

The mixture of silicon fine particles may contain silicon fine particles having different particle diameters. In this case, the pure silicon fine particles and the n-type silicon fine particles may have different particle sizes, or the pure silicon fine particles and the n-type silicon fine particles may be a mixture of silicon fine particles having different particle sizes. For example, when n-type silicon fine particles having a particle diameter smaller than that of pure silicon fine particles are used, when the two are uniformly mixed, the former voids can be distributed so as to fill the latter, and the spatial distribution of impurity atoms is uniform. Can be improved.

In terms of the filling rate, in the case of using a mixture of two kinds of fine particles, the filling rate can be maximized by setting the ratio of 3 fine particles having a small particle size to fine particles 7 having a large particle size. Although there is a paper, it is not necessary to use two kinds of Si fine particles for practical purposes.

The mixing ratio of the pure silicon fine particles and the n-type silicon fine particles is not particularly limited, and is appropriately determined according to the desired average concentration of impurity atoms, the particle diameter of the silicon fine particles, and the like. The mixing ratio of the pure silicon fine particles and the n-type silicon fine particles is preferably, for example, 100: 1 to 1,000,000: 1. If the ratio of the n-type silicon fine particles is too high, it is necessary to keep the number of impurity atoms per n-type silicon fine particle low, and it may be difficult to control the impurity atom concentration. On the other hand, if the proportion of the n-type silicon fine particles is too low, the distance between impurity atoms (phosphorus, etc.) that play a role in free electrons becomes too large, which may deteriorate the electron transfer characteristics.

In addition, the preferable impurity concentration made into the target of a coating film is about 10 < ¹¹ > -10 < ¹⁸ > / cm < ³ >, More preferably, it is about 10 < ¹² > -10 < ¹⁷ > / cm < ³ >.

The reaction liquid used for the production of the epoxidized silicon fine particle mixture includes an alkoxysilane compound containing an epoxy group, a condensation catalyst for accelerating the condensation reaction between the alkoxysilyl group and the hydroxyl group 15 on the surface of the silicon fine particle, and a non-aqueous system. It is prepared by mixing with an organic solvent.

The alkoxysilane compound containing an epoxy group has a functional group containing an epoxy group (oxirane ring) and an alkoxysilyl group at both ends of the linear alkylene group, and is represented by the following general formula (Formula 1). An alkoxysilane compound is preferable.

In the above formula, E represents a functional group containing an epoxy group, m represents an integer of 3 to 20, and R represents an alkyl group having 1 to 4 carbon atoms.

As an example of the alkoxysilane compound which has an epoxy group which can be used for manufacture of the epoxidized silicon fine particles 11 and 11a, the compounds shown in the following (11) to (22) may be mentioned.

(11) (CH ₂ OCH) CH ₂ O (CH ₂ ) ₃ Si (OCH ₃ ) ₃
(12) (CH ₂ OCH) CH ₂ O (CH ₂ ) ₇ Si (OCH ₃ ) ₃
(13) (CH ₂ OCH) CH ₂ O (CH ₂ ) ₁₁ Si (OCH ₃ ) ₃
(14) (CH ₂ CHOCH (CH ₂ ) ₂ ) CH (CH ₂ ) ₂ Si (OCH ₃ ) ₃
(15) (CH ₂ CHOCH (CH ₂ ) ₂ ) CH (CH ₂ ) ₄ Si (OCH ₃ ) _{3
(16) (CH 2 CHOCH (} CH 2) 2) CH (CH 2) 6 Si (OCH 3) 3
_{(17) (CH 2 OCH)} CH 2 O (CH 2) 3 Si (OC 2 H 5) 3
_{(18) (CH 2 OCH)} CH 2 O (CH 2) 7 Si (OC 2 H 5) 3
(19) (CH ₂ OCH) CH ₂ O (CH ₂ ) ₁₁ Si (OC ₂ H ₅ ) _{3
(20) (CH 2 CHOCH (} CH 2) 2) CH (CH 2) 2 Si (OC 2 H 5) 3
_{(21) (CH 2 CHOCH (} CH 2) 2) CH (CH 2) 4 Si (OC 2 H 5) 3
_{(22) (CH 2 CHOCH (} CH 2) 2) CH (CH 2) 6 Si (OC 2 H 5) 3

Here, the (CH ₂ OCH) CH ₂ O— group represents a functional group (glycidyloxy group) represented by Chemical Formula ₂ , and the (CH ₂ CHOCH (CH ₂ ) ₂ ) CH— group is represented by Chemical Formula 3. Represents a functional group (3,4-epoxycyclohexyl group).

As the condensation catalyst, metal salts such as carboxylic acid metal salts, carboxylic acid ester metal salts, carboxylic acid metal salt polymers, carboxylic acid metal salt chelates, titanate esters and titanate ester chelates can be used. By using such a catalyst, it is possible to react only an alkoxysilyl group at room temperature without causing a ring-opening reaction of the epoxy group.
The addition amount of the condensation catalyst is preferably 0.2 to 5% by mass of the alkoxysilane compound, and more preferably 0.5 to 1% by mass.

Specific examples of carboxylic acid metal salts include stannous acetate, dibutyltin dilaurate, dibutyltin dioctate, dibutyltin diacetate, dioctyltin dilaurate, dioctyltin dioctate, dioctyltin diacetate, stannous dioctanoate, naphthenic acid Lead, cobalt naphthenate, and iron 2-ethylhexenoate.

Specific examples of the carboxylic acid ester metal salt include dioctyltin bisoctylthioglycolate ester salt and dioctyltin maleate ester salt.
Specific examples of the carboxylic acid metal salt polymer include dibutyltin maleate polymer and dimethyltin mercaptopropionate polymer.
Specific examples of the carboxylic acid metal salt chelate include dibutyltin bisacetylacetate and dioctyltin bisacetyllaurate.

Specific examples of the titanate ester include tetrabutyl titanate and tetranonyl titanate.
Specific examples of titanate chelates include bis (acetylacetonyl) dipropyl titanate.

When the silicon fine particle mixture is immersed in the reaction solution and reacted in air at room temperature, the alkoxysilyl group and the hydroxyl group 15 on the surface of the silicon fine particle undergo a condensation reaction, resulting in a structure as shown in Chemical Formula 4 below. A monomolecular film 16 of an alkoxysilane compound having an epoxy group is generated. The three single bonds extending from the oxygen atom are bonded to the surface of the silicon fine particle or the silicon (Si) atom of the adjacent silane compound, and at least one of them is bonded to the silicon atom on the surface of the silicon fine particle. Yes.

Since the alkoxysilyl group decomposes in the presence of moisture, the reaction is preferably performed in air with a relative humidity of 45% or less. When any of the above metal salts is used as the condensation catalyst, the time required for completion of the condensation reaction is about 2 hours.

When one or more compounds selected from the group consisting of ketimine compounds, organic acids, aldimine compounds, enamine compounds, oxazolidine compounds, and aminoalkylalkoxysilane compounds are used as the condensation catalyst instead of the above metal salts, Time can be shortened to about 1/2 to 2/3.

Alternatively, when these compounds are used as a co-catalyst and mixed with the above-described metal salt (mass ratio 1: 9 to 9: 1 can be used, preferably around 1: 1), the reaction time is further shortened. it can.

For example, when the epoxidized silicon fine particles 11 and 11a are produced by using H3 of Japan Epoxy Resin Co., which is a ketimine compound instead of dibutyltin oxide as the condensation catalyst, and other conditions are the same, the epoxidized silicon fine particles 11, The reaction time can be shortened to about 1 hour without impairing the quality of 11a.

Further, as a condensation catalyst, a mixture of H3 and dibutyltin bisacetylacetonate (Japan 1: 1) is used as a condensation catalyst, and the other conditions are the same, and the epoxidized silicon fine particles 11 and 11a are produced. The reaction time can be shortened to about 20 minutes.

The ketimine compound that can be used here is not particularly limited, and examples thereof include 2,5,8-triaza-1,8-nonadiene, 3,11-dimethyl-4,7,10-triaza- 3,10-tridecadiene, 2,10-dimethyl-3,6,9-triaza-2,9-undecadiene, 2,4,12,14-tetramethyl-5,8,11-triaza-4,11-penta Decadiene, 2,4,15,17-tetramethyl-5,8,11,14-tetraaza-4,14-octadecadiene, 2,4,20,22-tetramethyl-5,12,19-triaza -4,19-trieicosadiene and the like.

Further, the organic acid that can be used is not particularly limited, and examples thereof include formic acid, acetic acid, propionic acid, butyric acid, malonic acid, and the like. Since the ring is opened, the addition amount is preferably 0.2 to 0.5% of the alkoxysilane compound.

For the preparation of the reaction solution, an organic chlorine solvent, a hydrocarbon solvent, a fluorocarbon solvent, a silicone solvent, and a mixed solvent thereof can be used. In order to prevent hydrolysis of the alkoxysilane compound, it is preferable to remove water from the desiccant or the solvent used by distillation. Moreover, it is preferable that the boiling point of a solvent is 50-250 degreeC.

Specific usable solvents include non-aqueous petroleum naphtha, solvent naphtha, petroleum ether, petroleum benzine, isoparaffin, normal paraffin, decalin, industrial gasoline, nonane, decane, kerosene, dimethyl silicone, phenyl silicone, and alkyl-modified silicone. , Polyether silicone, dimethylformamide and the like.
Furthermore, alcohol solvents such as methanol, ethanol, propanol, or a mixture thereof can also be used.

Fluorocarbon solvents that can be used include fluorocarbon solvents, Fluorinert (manufactured by 3M, USA), Afludo (manufactured by Asahi Glass Co., Ltd.), and the like. In addition, these may be used individually by 1 type and may mix 2 or more types as long as it mixes well. Furthermore, an organic chlorine solvent such as dichloromethane or chloroform may be added.

The preferable density | concentration of the alkoxysilane compound in a reaction liquid is 0.5-3 mass%.

After the reaction, the surface is covered with a monomolecular film 16 of an alkoxysilane compound having an epoxy group by washing with a solvent and removing excess alkoxysilane compound and condensation catalyst remaining on the surface as unreacted substances. 11 and 11a are obtained. Either continuous processing or batch processing may be used for cleaning. Separation of the cleaning solvent from the epoxidized silicon fine particles 11 and 11a can be performed using any known method such as filtration, decantation, and centrifugation. A schematic view of the cross-sectional structure of the epoxidized silicon fine particles 11 and 11a produced in this way is shown in FIG.

As the cleaning solvent, any solvent that can dissolve the alkoxysilane compound can be used, but dichloromethane, chloroform, N-methylpyrrolidone, etc. that are inexpensive, have high solubility, and can be easily removed by air drying are preferable. .

After the reaction, when the produced epoxidized silicon fine particles 11 and 11a are left in the air without being washed with a solvent, a part of the alkoxysilane compound remaining on the surface is hydrolyzed by moisture in the air, and the produced silanol group Causes a condensation reaction with an alkoxysilyl group. As a result, an ultrathin polymer film made of polysiloxane is formed on the surfaces of the epoxidized silicon fine particles 11 and 11a. Although this polymer film is not fixed to the surface of the epoxidized silicon fine particles 11 and 11a by a covalent bond, it contains an epoxy group. Therefore, the polymer film has a monomolecular film 16 of an alkoxysilane compound having an epoxy group with respect to an amino group. Similar reactivity. For this reason, even if the cleaning is not performed, the subsequent manufacturing process of the n-type silicon fine particle film 10 is not particularly hindered.

[2] Production of Aminated Silicon Fine Particle Mixture The aminated silicon fine particle mixture has an amino group and an alkoxysilyl group at both ends of a linear alkylene group as an alkoxysilane compound, respectively. It can be produced in the same manner as the above-mentioned epoxidized silicon fine particle mixture except that an alkoxysilane compound represented by

In the above formula, m represents an integer of 3 to 20, and R represents an alkyl group having 1 to 4 carbon atoms. The epoxy group may be protected with a protecting group in order to avoid side reactions with the alkoxysilyl group. The protecting group is preferably one that can be easily removed by hydrolysis or the like, and examples thereof include a ketimine derivative produced by the reaction between a ketone and an amino group.
The amino group may be a secondary amine other than the primary amine shown in Chemical Formula 5, and an alkoxysilane compound containing a functional group having an imino group such as a pyrrole group or an imidazole group may be used instead of the amino group. Can do.
In this case, examples of the alkoxysilane compound having an amino group that can be used include the compounds shown in the following (31) to (38).

(31) H ₂ N (CH ₂ ) ₃ Si (OCH ₃ ) ₃
(32) H ₂ N (CH ₂ ) ₅ Si (OCH ₃ ) ₃
(33) H ₂ N (CH ₂ ) ₇ Si (OCH ₃ ) ₃
(34) H ₂ N (CH ₂ ) ₉ Si (OCH ₃ ) ₃
(35) H ₂ N (CH ₂ ) ₅ Si (OC ₂ H ₅ ) ₃
(36) H ₂ N (CH ₂ ) ₅ Si (OC ₂ H ₅ ) _{3
(37) H 2 N (CH} 2) 7 Si (OC 2 H 5) 3
(38) H ₂ N (CH ₂ ) ₉ Si (OC ₂ H ₅ ) ₃

Among condensation catalysts, a compound containing a tin (Sn) salt reacts with an amino group contained in an alkoxysilane derivative to generate a precipitate, and thus cannot be used as a condensation catalyst. Therefore, when using an alkoxysilane compound having an amino group, except for a carboxylic acid tin salt, a carboxylic acid ester tin salt, a carboxylic acid tin salt polymer, and a carboxylic acid tin salt chelate, a compound similar to the reaction solution alone or Two or more types can be mixed and used as a condensation catalyst.

The types of cocatalysts that can be used and combinations thereof, the types of solvents, alkoxysilane compounds, condensation catalysts, and cocatalyst concentrations, reaction conditions, and reaction times are the same as in the production of the epoxidized silicon fine particles 11 and 11a. Therefore, detailed description is omitted here.

[3] Production of Reactive Substrate An alkoxysilane compound having an epoxy group or an amino group, which is the same as the alkoxysilane compound used in the production of the epoxidized silicon fine particle mixture and aminated silicon fine particle mixture, is brought into contact with the surface of the substrate. Then, a reactive substrate 13 whose surface is covered with a monomolecular film of an alkoxysilane compound is manufactured.

There are no particular restrictions on the size, shape, and thickness of the substrate, and any surface functional group can be used as long as it has a functional group that can react with an alkoxysilyl group to form a covalent bond. Can be used. As a base material used for photoelectric conversion elements such as solar cells and photosensors, a transparent base material having translucency such as glass may be used, and a conductive film such as ITO is formed on the surface as a transparent electrode. It may be. A metal such as aluminum or a synthetic resin such as polycarbonate can also be used.

When the surface of the base material has an active hydrogen group such as a hydroxyl group or an amino group, an alkoxysilane compound can be used as the second film compound as in the case of glass. Specific examples of such a substrate include metals such as aluminum, ceramics, and the like.
When a synthetic resin is used as the base material, an alkoxysilane compound may be used by performing a treatment such as grafting a compound having an active hydrogen group by plasma treatment or the like.

Types of alkoxysilane compounds, condensation catalysts, types of cocatalysts and combinations thereof that can be used for the production of the reactive substrate 13, types of solvents, concentrations of alkoxysilane compounds, condensation catalysts, and cocatalysts, reaction conditions, and Since the reaction time is the same as in the case of producing the epoxidized silicon fine particle mixture, the description thereof is omitted. In addition, an alkoxysilane compound having an epoxy group and an alkoxysilane compound having an amino group are mixed and used so as to be able to react with both the epoxidized silicon fine particles 11 and 11a and the aminated silicon fine particles 12 and 12a. A mixed monomolecular film may be formed.

After the reaction, the substrate is washed with a solvent, and the excess alkoxysilane compound and the condensation catalyst remaining on the surface as unreacted substances are removed to obtain the reactive substrate 13 whose surface is covered with a monomolecular film of the alkoxysilane compound. As the cleaning solvent, the same cleaning solvent as in the production of the epoxidized silicon fine particle mixture can be used.

After the reaction, when the generated reactive base material 13 is left in the air without washing with a solvent, a part of the alkoxysilane compound remaining on the surface is hydrolyzed by moisture in the air, and the generated silanol group is converted to alkoxy. Causes a condensation reaction with a silyl group. As a result, an ultrathin polymer film made of polysiloxane is formed on the surface of the reactive substrate 13. Although this polymer film is not fixed to the surface of the reactive substrate 13 by a covalent bond, it contains an epoxy group or an amino group, so that the following manufacturing process is particularly hindered without cleaning. There is no.

[4] Production of paste A paste is produced by mixing the epoxidized silicon fine particle mixture and the aminated silicon fine particle mixture produced in the steps [1] and [2], respectively, in an organic solvent. The amount of the solvent used for the production of the paste is appropriately determined depending on the particle size of the silicon fine particles, the film thickness of the n-type silicon fine particle film 10 to be produced, etc. Is preferably about 5 to 300 Pa · s, more specifically 10 to 50% by weight of the silicon fine particles. The epoxidized silicon fine particle mixture, the aminated silicon fine particle mixture, and the solvent can be mixed by any means such as a stirring spring and a hand mixer.

[5] Application of paste The paste can be applied to the surface of the reactive substrate 13 by any method such as an ink jet method, a doctor blade method, a spin coating method, or a spray method. The film thickness of the coating film to be formed can be appropriately controlled by the viscosity of the paste, the solvent content, the particle size of the silicon fine particles used as a raw material, the number of coatings, and the like.

[6] Curing of coating film Next, the coating film is heated, and the coating film is cured by bond formation between epoxy groups and amino groups on the silicon microparticles and the reactive substrate 13 to produce the n-type silicon microparticle film 10.
The heating temperature is preferably 50 to 200 ° C. If the heating temperature is less than 50 ° C, it takes a long time for the crosslinking reaction to proceed. If the heating temperature exceeds 200 ° C, the crosslinking reaction proceeds rapidly on the surface of the coating film, and the confined solvent is less likely to volatilize. The uniform n-type silicon fine particle film 10 cannot be obtained.

Although the reactive base material 13 is used in the present embodiment, a base material on which no monomolecular film of an alkoxysilane compound is formed may be used directly.

The bond used for forming the molecular bridge may be any of a covalent bond, an ionic bond, a coordinate bond, and a bond due to intermolecular force. However, the strength and paste of the formed n-type silicon fine particle film 10 In consideration of the ease of forming the coating film, a covalent bond formed by heating or irradiation with energy rays such as light is preferable after the coating film is formed.
As a specific example of the covalent bond formed by heating, in addition to the N—CH ₂ CH (OH) bond formed by a reaction between an epoxy group and an amino group or an imino group, it is formed by a reaction between an isocyanate group and an amino group. NH-CONH bond may be used.

Specific examples of the covalent bond formed by light irradiation include a covalent bond formed by a photodimerization reaction of a cinnamoyl group or a chalconyl group.

Next, a semiconductor fine particle film according to a second embodiment of the present invention will be described.
As shown in FIG. 3, the n-type silicon fine particle film 20 according to the second embodiment of the present invention includes an alkoxysilane compound having an epoxy group (an example of a fourth reactive functional group) at one end of the molecule ( A mixture of epoxidized pure silicon fine particles 31 and epoxidized n-type silicon fine particles 31a (at least part of the surface of which is coated with a monomolecular film (an example of a fourth film) formed by an example of a fourth film compound) An example of a fourth reactive silicon fine particle mixture) and 2-methylimidazole (an example of a second cross-linking agent), and the epoxidized silicon fine particles 31 and 31a include an epoxy group and an amino group of 2-methylimidazole. And is formed and cured via a bond formed by reaction with an imino group (an example of a crosslinking reactive group).

The n-type silicon fine particle film 20 is manufactured by a method including the following steps [1] to [5].
[1] An alkoxysilane compound having an epoxy group (an example of a fourth film compound) is brought into contact with a silicon fine particle mixture to form a Si—O— bond between the alkoxysilyl group and the hydroxyl group on the surface of the silicon fine particle. , A mixture of epoxidized pure silicon fine particles 21 and epoxidized n-type silicon fine particles 21a, the surface of which is at least partially covered with a monomolecular film of an alkoxysilane compound having an epoxy group (an example of a fourth reactive silicon fine particle mixture: Hereinafter, the step [2] of producing a paste by mixing the epoxidized silicon fine particle mixture and 2-methylimidazole in an organic solvent [3]. ] An alkoxysilane compound having an epoxy group (an example of a fourth film compound) is brought into contact with the substrate surface. , A Si—O— bond is formed between the alkoxysilyl group and the surface functional group of the base material, and at least a part of the surface is a monomolecular film (an example of the fourth film) of an alkoxysilane compound having an epoxy group. Step [4] for manufacturing the coated reactive base material 23 [4] Step for applying a paste containing the epoxidized silicon fine particle mixture and 2-methylimidazole to the surface of the reactive base material [5] Epoxy group and amino group or A process of forming a N—CH ₂ CH (OH) bond by reaction with an imino group (an example of a crosslinking reactive group) and curing a coating film of a paste.

Hereinafter, each process will be described in more detail.
[1] Production of Epoxidized Silicon Fine Particles As for the production of the epoxidized silicon fine particles 21, the epoxidized silicon fine particles 11 and 11a are produced in the production of the n-type silicon fine particle film 10 according to the first embodiment of the present invention. Detailed description is omitted.

[2] Production of Paste The epoxidized silicon fine particle mixture produced as described above and 2-methylimidazole are mixed in an organic solvent to produce a paste. 2-methylimidazole has an amino group (> NH) and an imino group (= N-) which react with an epoxy group at the 1-position and 3-position, respectively, and a crosslinking reaction as shown in the following chemical formula 6 To form a chemical bond.

The addition amount of 2-methylimidazole needs to be controlled depending on the size of the silicon fine particles, but is preferably 0.5 to 15% by weight of the epoxidized silicon fine particle mixture. If the amount of 2-methylimidazole added is extremely small compared to the number of epoxy groups on the surface of the epoxidized silicon fine particle mixture, the mechanical strength of the resulting n-type silicon fine particle film 20 will be low. Since it exceeds the requirement of 2-methylimidazole required for the reaction, it is not economical.

Regarding the type and amount of the organic solvent used in the manufacture of the paste, the stirring method, etc., the paste containing the epoxidized silicon fine particles 11 and 11a in the production of the n-type silicon fine particle film 10 according to the first embodiment of the present invention is used. Since it is the same as in the case of manufacturing, detailed description is omitted.

In the present embodiment, 2-methylimidazole is used as a crosslinking agent, but any imidazole derivative represented by the following chemical formula 7 can be used. Alternatively, an imidazole-metal complex or triazole may be used.

Specific examples of the imidazole derivative represented by Chemical formula 7 include those shown in the following (41) to (48).
(41) 2-methylimidazole (R ₂ = Me, R ₄ = R ₅ = H)
(42) 2-undecyl imidazole _{(R 2 = C 11 H 23} , R 4 = R 5 = H)
(43) 2-pentadecyl-imidazole _{(R 2 = C 15 H 31} , R 4 = R 5 = H)
(44) 2-methyl-4-ethylimidazole _{(R 2 = Me, R 4} = Et, R 5 = H)
(45) 2-Phenylimidazole (R ₂ = Ph, R ₄ = R ₅ = H)
(46) 2-phenyl-4-ethylimidazole _{(R 2 = Ph, R 4} = Et, R 5 = H)
(47) 2-phenyl-4-methyl-5-hydroxymethylimidazole _{(R 2 = Ph, R 4} = Me, R 5 = CH 2 OH)
(48) 2-Phenyl-4,5-bis (hydroxymethyl) imidazole (R ₂ = Ph, R ₄ = R ₅ = CH ₂ OH)
Me, Et, and Ph represent a methyl group, an ethyl group, and a phenyl group, respectively.

Further, acid anhydrides such as phthalic anhydride and maleic anhydride used as a curing agent for epoxy resins, phenol derivatives such as dicyandiamide and novolac, and compounds such as triazole may be used as the second crosslinking agent. In this case, an imidazole derivative may be used as a catalyst in order to accelerate the crosslinking reaction.

In this embodiment, the case of using a film compound having an epoxy group is described. However, in the case of using a film compound having an amino group or an imino group, 2 or 3 or more epoxy groups are used as a cross-linking reactive group. Or a coupling agent having two or more isocyanate groups. Specific examples of the compound having an isocyanate group include hexamethylene-1,6-diisocyanate, toluene-2,6-diisocyanate, and toluene-2,4-diisocyanate.
The addition amount of these diisocyanate compounds is preferably 5 to 15% by weight of the epoxidized silicon fine particles as in the case of 2-methylimidazole. In this case, examples of the solvent that can be used for the production of the film precursor include aromatic organic solvents such as xylene.
Moreover, as a crosslinking agent, the compound which has 2 or 3 or more epoxy groups, such as ethylene glycol diglycidyl ether, can also be used.

[3] Production of reactive substrate,
Except for using an alkoxysilane compound having an epoxy group as the alkoxysilane compound, it is the same as the production of the reactive substrate 13 in the production of the n-type silicon fine particle film 10 according to the first embodiment of the present invention. Description is omitted.

[4] The steps of applying the paste and [5] curing the coating film are the same as the corresponding steps in the manufacture of the n-type silicon fine particle film 10 according to the first embodiment of the present invention. Detailed explanation is omitted.

In each of the above-described embodiments, epoxidation is performed using a mixture of pure silicon fine particles and n-type silicon fine particles uniformly mixed so that the average concentration of impurity atoms is 10 ¹⁰ to 10 ²⁰ cm ⁻³ as a starting material. Although the n-type silicon fine particle mixture and the aminated n-type silicon fine particle mixture were produced, a mixture of two or more types of n-type silicon fine particles having different impurity atom concentrations may be used.

Alternatively, for each of pure silicon fine particles and n-type silicon fine particles or two or more types of n-type silicon fine particles having different impurity atom concentrations, epoxidized n-type silicon fine particles and aminated n-type silicon are obtained using the same procedure as described above. After each fine particle is produced, the paste may be produced by mixing them at a mixing ratio such that the average concentration of impurity atoms is a desired value within the above-mentioned range.

In the n-type silicon fine particle films 10 and 20 according to the respective embodiments of the present invention, unreacted reactive functional groups (for example, epoxy groups and amino groups) remain in the reactive silicon fine particle mixture located on the surface layer. Therefore, the p-type silicon fine particle film can be laminated thereon by using the same procedure as the above method, and a pn junction can be formed. The semiconductor fine particle film having a pn junction manufactured in this way exhibits diode characteristics such as rectification. Therefore, the present invention also provides a diode and its inexpensive and simple manufacturing method.

In addition, since the film thickness of the n-type and p-type silicon fine particle films can be controlled in the order of nm to μm, and the light transmittance can be secured, the diode provided by the present invention can be applied to various photoelectric conversion elements. In FIG. 4, the schematic diagram of the cross-section of the solar cell 50 which is an example of a photoelectric conversion element is shown. An n-type silicon fine particle film 51 and a p-type silicon fine particle film 52 formed using any one of the above methods are laminated on an ITO substrate 53 which is a transparent electrode on the light incident side. An aluminum electrode 54 is deposited on the p-type silicon fine particle film 52. An antireflection film (not shown) may be provided between the n-type silicon fine particle film 51 and the ITO substrate 53, or between the n-type silicon fine particle film 51 and the p-type silicon fine particle film 52. Alternatively, a structure having a pin junction provided with a pure silicon fine particle film may be used. Further, the n-type silicon fine particle film 51 and the p-type silicon fine particle film 52 do not have to be flat, and may be laminated so as to have a zigzag type cross section.

Hereinafter, although the detail of this invention is demonstrated using an Example, this invention is not limited at all by these Examples.

Example 1: Production of n-type silicon fine particle film [1]
(1) Production of Epoxidized Silicon Fine Particle Mixture Pure silicon fine particles having an average particle diameter of 10 nm and n-type silicon fine particles having an average particle diameter of 10 nm (impurity atom concentration 10 ¹⁹ cm ⁻³ ) are prepared, and the weight ratio is 99.99: 0. It mixed so that it might become 01. The silicon fine particle mixture thus obtained (average concentration of impurity atoms: 10 ¹⁶ cm ⁻³ ) was thoroughly dried.
Here, the preferable impurity concentration targeted for the coating film is about 10 ¹¹ to 10 ¹⁸ / cm ³ , more preferably about 10 ¹² to 10 ¹⁷ / cm ^3. However, if the mixing conditions are adjusted as necessary, Good.

0.99 parts by weight of 3-glycidyloxypropyltrimethoxysilane (Chemical Formula 8) and 0.01 parts by weight of dibutyltin bisacetylacetonate (condensation catalyst) are weighed and dissolved in 100 parts by weight of hexamethyldisiloxane solvent. The reaction solution was prepared.

The silicon fine particle mixture was dispersed in the reaction solution thus obtained and reacted in air (relative humidity 45%) for about 2 hours while stirring.
Thereafter, it was washed with ethanol to remove excess alkoxysilane compound and dibutyltin bisacetylacetonate.

(2) Production of aminated silicon fine particle mixture A silicon fine particle mixture having the average particle diameter of about 10 nm (same as that used in (1)) was prepared and dried well.
0.99 parts by weight of 3-aminopropyltrimethoxysilane (Chemical 9; manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.01 part by weight of acetic acid (condensation catalyst) were weighed and added to 100 parts by weight of a hexamethyldisiloxane solvent. To prepare a reaction solution.

Silicon fine particles were dispersed in the reaction solution thus obtained, and reacted in air (relative humidity 45%) for about 2 hours while stirring.
Thereafter, it was washed with ethanol to remove excess alkoxysilane compound and dibutyltin bisacetylacetonate.

(3) Production of silicon fine particle paste 50 parts by weight of the epoxidized silicon fine particle mixture produced in (1) and 50 parts by weight of the aminated silicon fine particle mixture produced in (2) are mixed, and 40 parts by weight of isopropyl alcohol are mixed therewith. Was added. The obtained mixture was sufficiently mixed to obtain a silicon fine particle paste.

(4) Production of epoxidized glass substrate A glass substrate was prepared, washed well and dried.
0.99 parts by weight of 3-glycidyloxypropyltrimethoxysilane (Chemical Formula 8) and 0.01 parts by weight of dibutyltin bisacetylacetonate (condensation catalyst) were weighed, and 100 parts by weight of hexamethyldisiloxane-dimethylformamide was measured. The reaction solution was prepared by dissolving in a mixed solvent (1: 1 v / v).

The reaction solution was applied to the surface of the glass substrate and reacted in air (relative humidity 45%) for about 2 hours. Thereafter, the mixture was washed with chloroform to remove excess alkoxysilane compound and dibutyltin bisacetylacetonate.

(5) Formation of coating film and formation of n-type silicon fine particle film The silicon fine particle paste produced in (3) is applied on the epoxidized glass substrate produced in (4) to form a coating film having a thickness of 3 μm. did.
After evaporating isopropyl alcohol at room temperature, the glass substrate and the coating film formed thereon were heated at 170 ° C. for 30 minutes to form an n-type silicon fine particle film.

Example 2: Method for producing n-type silicon fine particle film [2]
In the same manner as in Example 1 (1), 100 parts by weight of an epoxidized silicon fine particle mixture produced using an n-type silicon fine particle mixture adjusted to have an average n-type impurity atom concentration of 10 ¹⁷ cm ⁻³ was added to 2- 5 parts by weight of methylimidazole and 40 parts by weight of isopropyl alcohol were added. The obtained mixture was sufficiently mixed to obtain a silicon fine particle paste. The silicon fine particle paste thus produced was applied on the epoxidized glass substrate produced in the same manner as in Example 1 (4) to form a coating film having a thickness of 3 μm.
After evaporating isopropyl alcohol at room temperature, the glass substrate and the coating film formed thereon were heated at 170 ° C. for 30 minutes to form an n-type silicon fine particle film.
The preferable impurity concentration targeted for the coating film is about 10 ¹¹ to 10 ¹⁸ / cm ³ , more preferably about 10 ¹² to 10 ¹⁷ / cm ³ , but the mixing conditions may be adjusted as necessary.

Example 3: Production of n-type silicon fine particle film [3]
5 parts by weight of hexamethylene-1,6-diisocyanate and 40 parts by weight of isopropyl alcohol were added to 100 parts by weight of the aminated silicon fine particle mixture produced in the same manner as (2) of Example 1. The obtained mixture was sufficiently mixed to obtain a silicon fine particle paste. The silicon fine particle paste thus produced was applied on the epoxidized glass substrate produced in the same manner as in Example 1 (4) to form a coating film having a thickness of 3 μm.
After evaporating isopropyl alcohol at room temperature, the glass substrate and the coating film formed thereon were heated at 170 ° C. for 30 minutes to form an n-type silicon fine particle film.

Example 4: Production of n-type silicon fine particle film [4]
Without mixing pure silicon fine particles having an average particle diameter of 10 nm and n-type silicon fine particles having an average particle diameter of 10 nm (impurity atom concentration of 10 ¹⁹ cm ⁻³ ), the same as in (1) and (2) of Example 1 After producing epoxidized pure silicon fine particles, epoxidized n-type silicon fine particles, aminated pure silicon fine particles and aminated n-type silicon fine particles, these were prepared 99.9: 0.1: 99.9: 0.1. An n-type silicon fine particle film was produced by the same procedure as in Example 1 except that the paste was produced using the same procedure as in Example 1 (3).

Example 5: Preparation of solar cell [1]
A monomolecular film of an alkoxysilane compound having an epoxy group was formed on the surface of the ITO glass plate by the same procedure as (4) of Example 1. An ethanol dispersion of the aminated n-type silicon fine particle mixture produced in the same manner as in Example 1 (2) was applied to the surface of the epoxidized ITO glass plate thus produced and heated at 100 ° C. After the reaction, the mixture was washed with water to remove excess aminated n-type silicon fine particle mixture.
Next, an ethanol dispersion of an epoxidized p-type silicon fine particle mixture produced in the same manner as in Example 1 (1) except that p-type silicon fine particles were used instead of n-type silicon fine particles was further applied and heated at 100 ° C. did. Furthermore, when an aluminum electrode was deposited thereon, a solar cell having a diode structure was obtained.

Example 6: Preparation of solar cell [2]
A monomolecular film of an alkoxysilane compound having an epoxy group was formed on the surface of the ITO glass plate by the same procedure as (4) of Example 1. The paste containing the n-type silicon fine particle mixture produced in the same manner as in Example 2 was applied to the surface of the epoxidized ITO glass plate thus produced, and the resulting coating film was heated at 170 ° C. for 30 minutes.
Next, a paste containing a mixture of p-type silicon fine particles produced in the same manner as in Example 2 was applied except that p-type silicon fine particles were used in place of the n-type silicon fine particles, and the obtained coating film was heated at 170 ° C. for 30 minutes. did. Then, the solar cell was obtained when the aluminum electrode was vapor-deposited on it.

The solar cell can be easily downsized, and a photosensor can be manufactured by the same manufacturing method as described above.

10, 20 n-type silicon fine particle layers 11, 21 Epoxidized pure silicon fine particles 11a, 21a Epoxidized n-type silicon fine particles 12 Aminated pure silicon fine particles 12a Aminated n-type silicon fine particles 13, 23 Reactive substrate 14 Pure silicon fine particles 15 Monomolecular film 50 of alkoxysilane compound having hydroxyl group 16 epoxy group Solar cell 51 n-type silicon fine particle layer 52 p-type silicon fine particle layer 53 ITO electrode 54 Aluminum electrode

Claims (6)

A step of producing a silicon fine particle mixture in which two or more types of silicon fine particles having different impurity atom concentrations are uniformly mixed so that an average concentration of impurity atoms is 10 ¹⁰ to 10 ²⁰ cm ⁻³ ;
A first film compound having a first reactive functional group and a halosilyl group or alkoxysilyl group, respectively, is brought into contact with the mixed silicon fine particle mixture, and the mixed silicon fine particle mixture and the halosilyl group or alkoxysilyl group First reactive silicon fine particles in which at least a part of the surface is covered with a first film formed by the first film compound by forming a Si—O— bond with a surface functional group of the silicon fine particles. Producing a mixture;
Separately, a second reactive functional group that reacts with the first reactive functional group by heat to form a chemical bond and a second film compound each having a halosilyl group or an alkoxysilyl group are the same as described above. Contact with a silicon fine particle mixture to form a Si—O— bond between the halosilyl group or alkoxysilyl group and the surface functional group of the silicon fine particle, and the surface with a second film formed of the second film compound Producing a second reactive silicon particulate mixture that is at least partially covered by:
Mixing the first reactive silicon fine particle mixture and the second reactive silicon fine particle mixture in an organic solvent to produce a paste;
Applying the paste to the substrate surface;
Wherein the reaction of the first reactive functional group and the second reactive functional groups to form chemical bonds, see containing and curing the coating film of the paste, different the impurity atom concentration 2 The method for producing a semiconductor fine particle film, wherein the silicon fine particles of a kind or more include pure silicon fine particles and p-type or n-type silicon fine particles . The first reactive functional group and the first film compound each having a halosilyl group or an alkoxysilyl group are brought into contact with two or more types of silicon fine particles having different impurity atom concentrations, and the halosilyl group or alkoxysilyl group Si—O— bonds are formed with the surface functional groups of the silicon fine particles, and at least a part of the surface is covered with a first film formed by the first film compound. Producing reactive silicon fine particles;
The second reactive functional group that reacts with the first reactive functional group by heat to form a chemical bond and the second film compound each having a halosilyl group or an alkoxysilyl group are used as the two or more types of silicon. Contact with each of the fine particles to form Si—O— bonds between the halosilyl group or alkoxysilyl group and the surface functional groups of the silicon fine particles, and the surface with the second film formed by the second film compound A step of producing two or more kinds of second reactive silicon fine particles covered at least in part,
The two or more types of first reactive silicon fine particles and the two or more types of second reactive silicon fine particles are uniformly mixed with an organic solvent so that an average concentration of impurity atoms is 10 ¹⁰ to 10 ²⁰ cm ^−3. Mixing in to produce a paste comprising a reactive silicon particulate mixture;
Applying the paste to the substrate surface;
Wherein the reaction of the first reactive functional group and the second reactive functional groups to form chemical bonds, see containing and curing the coating film of the paste, different the impurity atom concentration 2 The method for producing a semiconductor fine particle film, wherein the silicon fine particles of a kind or more include pure silicon fine particles and p-type or n-type silicon fine particles . A third reactive functional group that reacts with one or both of the first and second reactive functional groups and a halosilyl group or an alkoxysilyl group on the substrate surface before applying the paste in advance. The film compound is contacted, and a Si—O— bond is formed between the halosilyl group or alkoxysilyl group and the surface functional group of the substrate, and the surface is formed by the third film formed by the third film compound. The method for producing a semiconductor fine particle film according to claim 1, further comprising a step of producing a reactive substrate in which at least a part of the substrate is covered. A step of producing a silicon fine particle mixture in which two or more types of silicon fine particles having different impurity atom concentrations are uniformly mixed so that an average concentration of impurity atoms is 10 ¹⁰ to 10 ²⁰ cm ⁻³ ;
A fourth film compound having a fourth reactive functional group and a halosilyl group or alkoxysilyl group, respectively, is brought into contact with the silicon fine particle mixture, and the surface functional groups of the silicon fine particles mixed with the halosilyl group or alkoxysilyl group. Forming a fourth reactive silicon fine particle mixture in which at least a part of the surface is covered with a film formed by the fourth film compound;
Paste obtained by mixing the fourth reactive silicon fine particle mixture and a crosslinking agent having a plurality of crosslinking reactive groups that react with heat with the fourth reactive functional group to form a chemical bond in an organic solvent. Manufacturing process,
Applying the paste to the substrate surface;
To form a chemical bond by reaction with the crosslinking reactive group and the fourth reactive functional groups, see containing and curing the coating film of the paste, 2 kinds or more of silicon microparticles having the different impurity atom concentration Comprises a pure silicon fine particle and a p-type or n-type silicon fine particle . A fourth film compound having a fourth reactive functional group and a halosilyl group or an alkoxysilyl group, respectively, is contacted separately with two or more silicon fine particles having different impurity concentrations, and the halosilyl group or alkoxysilyl group Two types having different impurity atom concentrations, at least part of the surface of which is formed by forming a Si—O— bond with the surface functional group of each of the silicon fine particles, and covering at least part of the surface with the coating formed by the fourth film compound. A step of producing each of the fourth reactive silicon fine particles,
A fourth reactive silicon fine particle mixture in which two or more types of fourth reactive silicon fine particles having different impurity atom concentrations are uniformly mixed so that an average concentration of impurity atoms is 10 ¹⁰ to 10 ²⁰ cm ⁻³ . Manufacturing process,
Paste obtained by mixing the fourth reactive silicon fine particle mixture and a crosslinking agent having a plurality of crosslinking reactive groups that react with heat with the fourth reactive functional group to form a chemical bond in an organic solvent. Manufacturing process,
Applying the paste to the substrate surface;
To form a chemical bond by reaction with the crosslinking reactive group and the fourth reactive functional groups, see containing and curing the coating film of the paste, 2 kinds or more of silicon microparticles having the different impurity atom concentration Comprises a pure silicon fine particle and a p-type or n-type silicon fine particle . In advance, the fourth film compound is brought into contact with the substrate surface before the paste is applied, and a Si—O— bond is formed between the halosilyl group or alkoxysilyl group and the surface functional group of the substrate. 6. The semiconductor according to claim 4, further comprising a step of manufacturing a reactive base material in which at least a part of the surface is covered with the fourth film formed by the fourth film compound. Manufacturing method of fine particle film.