JP6132387B2 - Semiconductor nanoparticles, semiconductor nanoparticle-supporting electrode, and method for producing semiconductor nanoparticles - Google Patents

Description

  The present invention relates to a semiconductor nanoparticle, a semiconductor nanoparticle-supporting electrode, and a method for producing a semiconductor nanoparticle.

Various materials are being searched for with the aim of creating high-efficiency solar cells. In recent years, it has been reported that a high-efficiency solar cell can be produced using a chalcopyrite semiconductor such as CuInSe ₂ (CIS), which is a compound semiconductor, and has attracted attention as a next-generation solar cell that replaces a silicon solar cell. For example, Patent Document 1 proposes a method for producing high-quality chalcopyrite nanoparticles. Although the use of chalcopyrite nanoparticles is expected to make it easier to fabricate photoelectric conversion devices, etc., since it contains In, a rare element, there is concern about a stable supply in the future, and the search for alternative materials continues. It has been.

Ag ₈ SnS ₆ is drawing attention as a semiconductor that does not contain rare metals or highly toxic elements (Non-patent Documents 1-3). For example, in Non-Patent Document 1, Ag ₈ SnS ₆ is obtained by placing a mixture of S, SnCl ₂ and AgNO _{3 in} an autoclave, sealing the autoclave, heating at 180 ° C. for 14 hours, and then naturally cooling to room temperature. It has gained. The average particle size of this Ag ₈ SnS ₆ is about 60 nm.

JP 2008-192542 A

Materials Research Bulletin, vol. 36 (2001), p2649-2656 Crystal Growth Design, vol.12 (2012), p3458-3464 Materials Research Bulletin, vol. 38 (2003), p823-830

However, Ag ₈ SnS ₆ having an even smaller average particle diameter has not been known so far.

The present invention has been made in order to solve such problems, and is a semiconductor nanoparticle mainly composed of Ag ₈ SnZ ₆ (Z is S or Se), and has an average particle size much higher than that of the conventional one. The main purpose is to provide small things.

In order to achieve the above-mentioned object, the present inventors put Ag (S ₂ CNEt ₂ ) and Sn (S ₂ CNEt ₂ ) in oleylamine with heating and stirring, and precipitate the precipitate from the resulting suspension. It was recovered and the precipitate was dissolved in hexane. As a result, it was found that a solution of semiconductor nanoparticles having an average particle size of 20 nm or less was obtained, and the present invention was completed.

That is, the semiconductor nanoparticles of the present invention are particles mainly composed of Ag ₈ SnZ ₆ (where Z is S or Se), and have a particle size of 20 nm or less.

  The semiconductor nanoparticle carrying electrode of the present invention is obtained by carrying the above-mentioned semiconductor nanoparticles on a porous metal oxide electrode carrier.

  The first production method of the semiconductor nanoparticles of the present invention is a method in which an Ag complex having a ligand having Z (where Z is S or Se) as a coordination element and an Sn complex having the ligand are made of metal. It was put in an alkylamine or alkenylamine having a hydrocarbon group having 4 to 20 carbon atoms so that the molar ratio of the source was Ag: Sn = 8: x (x = 1 to 8), and the temperature was 150 to 350 ° C. The mixture is heated and stirred, and the precipitate is recovered from the obtained suspension, and the precipitate is dissolved in an organic solvent to obtain a solution of semiconductor nanoparticles.

  The second method for producing the semiconductor nanoparticles of the present invention is to prepare an Ag salt, an Sn salt, and thiourea or selenourea in a molar ratio of Ag: Sn: S (or Se) = 8: x: y (where x = 1-8, y = 1-60) so as to be placed in an alkylamine or alkenylamine having a hydrocarbon group having 4 to 20 carbon atoms, heated and stirred at 150 to 350 ° C., and the resulting suspension The precipitate is recovered from the liquid, and the precipitate is dissolved in an organic solvent to obtain a semiconductor nanoparticle solution.

  According to the semiconductor nanoparticles of the present invention, good photoelectrochemical properties can be obtained. In particular, a semiconductor nanoparticle-supporting electrode in which the semiconductor nanoparticles are supported on a porous metal oxide carrier exhibits a photosensitizing action, and is expected to be used for a photosensitized solar cell. In addition, according to the first and second methods for producing semiconductor nanoparticles of the present invention, the semiconductor nanoparticles described above can be produced relatively easily, and the temperature of the semiconductor nanoparticles can be adjusted by adjusting the temperature during heating. The average particle size can be controlled within a range of 20 nm or less.

The schematic diagram of a semiconductor nanoparticle solution. XRD patterns of Comparative Examples 1 and 2 and Examples 1 to 4. Absorption spectra of Comparative Examples 1 and 2 and Examples 1 to 4. The graph showing the relationship between Sn preparation ratio x of the comparative examples 1 and 2 and Examples 1-4, and the ratio of a metal atom. TEM images of Ag ₈ SnS ₆ nanoparticles of Example 1-4. The graph showing the relationship between Sn preparation ratio x of Examples 1-4 and a particle size. The XRD pattern of Examples 5-8 and Example 2. FIG. The absorption spectrum of Examples 5-8 and Example 2. FIG. The graph showing the relationship between the reaction temperature of Examples 5-8 and Example 2, and the ratio of a metal atom. TEM images of Ag ₈ SnS ₆ nanoparticles of Examples 5 to 8 and Example 2. The graph showing the relationship between the reaction temperature of Examples 5-8 and Example 2, and a particle size. The diffuse reflection spectrum of the electrode of Example 9. The diffuse reflection spectrum of the electrode of Example 10. The current-potential curve at the time of light irradiation and darkness in Example 9. The electric current-potential curve at the time of light irradiation of Example 10 and darkness. The graph showing the relationship between the wavelength of Examples 9 and 10 and IPCE. The XRD pattern of the nanoparticles of Example 11. Absorption spectrum of Example 11. TEM image of nanoparticles of Example 11. Particle size distribution of Example 11.

The semiconductor nanoparticles of the present invention are particles mainly composed of Ag ₈ SnZ ₆ (where Z is S or Se), and have a particle size of 20 nm or less.

In the semiconductor nanoparticles of the present invention, the surface of particles mainly composed of Ag ₈ SnZ ₆ is preferably modified with an alkylamine or alkenylamine having a hydrocarbon group having 4 to 20 carbon atoms. Examples of the alkylamine having a hydrocarbon group having 4 to 20 carbon atoms include n-butylamine, isobutylamine, n-pentylamine, n-hexylamine, octylamine, decylamine, dodecylamine, hexadecylamine and octadecylamine. Can be mentioned. Moreover, oleylamine etc. are mentioned as an alkenylamine which has a C4-C20 hydrocarbon group. These amines can be bonded to the particle surface, and examples of the bonding mode include chemical bonds such as a covalent bond, an ionic bond, a coordinate bond, a hydrogen bond, and a van der Waals bond.

  In order to efficiently absorb near-infrared light from visible light, the semiconductor nanoparticles of the present invention preferably have an absorption edge on the long wavelength side of the absorption spectrum of 800 nm or more, more than visible light in sunlight. It is preferable to absorb near infrared light having a long wavelength. In this case, it is expected that the performance is improved when the electrode carrying the semiconductor nanoparticles is incorporated into a solar cell.

The semiconductor nanoparticle carrying electrode of the present invention is obtained by carrying the above-mentioned semiconductor nanoparticles on a porous metal oxide electrode carrier. Examples of the metal oxide include ZnO, TiO ₂ , WO ₃ , SnO ₂ , In ₂ O ₃ , Al ₂ O _{3 and the} like, and the metal oxide has various particle shapes such as a spherical shape and a rod shape. Can be used. A porous metal oxide electrode carrier can be obtained by fixing these metal oxide particles on an electrode substrate such as an FTO substrate. The loading of the semiconductor nanoparticles on the electrode carrier may be performed by repeating the operation of dipping the porous metal oxide electrode carrier a plurality of times in the semiconductor nanoparticle solution in which the semiconductor nanoparticles are dissolved in an organic solvent. Good. Alternatively, the operation of dipping once in the semiconductor nanoparticle solution and then once dipping in the cross-linking agent solution may be repeated a plurality of times. Examples of the crosslinking agent include ethylenediamine (EDA) and ethanedithiol. By using such a crosslinking agent, since the semiconductor nanoparticles are crosslinked, the semiconductor nanoparticles can be firmly fixed to the nanorods.

  The semiconductor nanoparticle-supporting electrode of the present invention preferably has an absorption edge on the long wavelength side of the IPCE spectrum of 800 nm or more, and preferably responds by irradiating near infrared light from visible light. In this case, since near-infrared light having a wavelength longer than that of visible light is absorbed in sunlight, it is expected that the performance is improved when the semiconductor nanoparticle-supporting electrode is incorporated in a solar cell.

The first production method of the semiconductor nanoparticles of the present invention is a method in which an Ag complex having a ligand having Z (where Z is S or Se) as a coordination element and an Sn complex having the ligand are made of metal. It is placed in an alkylamine or alkenylamine having a hydrocarbon group having 4 to 20 carbon atoms so that the molar ratio of the source is Ag: Sn = 8: x (where x = 1 to 8), and 150 to 350 The mixture is heated and stirred at 0 ° C., and the precipitate is recovered from the obtained suspension, and the precipitate is dissolved in an organic solvent to obtain a solution of semiconductor nanoparticles. According to this production method, particles having Ag ₈ SnZ ₆ (where Z is S or Se) as a main component and having a particle size of 20 nm or less can be obtained relatively easily.

  In the first method for producing semiconductor nanoparticles of the present invention, the ligand is preferably a ligand having S as a coordination element. Examples of such ligands include β-dithiones such as 2,4-pentanedithione; dithiols such as 1,2-bis (trifluoromethyl) ethylene-1,2-dithiol; and diethyldithiocarbamic acid. And dialkyldithiocarbamic acid. Of these, dialkyldithiocarbamic acid is preferred.

The second method for producing the semiconductor nanoparticles of the present invention is to prepare an Ag salt, an Sn salt, and thiourea or selenourea in a molar ratio of Ag: Sn: S (or Se) = 8: x: y (where x = 1-8, y = 1-60) so as to be placed in an alkylamine or alkenylamine having a hydrocarbon group having 4 to 20 carbon atoms, heated and stirred at 150 to 350 ° C., and the resulting suspension The precipitate is recovered from the liquid, and the precipitate is dissolved in an organic solvent to obtain a semiconductor nanoparticle solution. Also by this production method, particles having Ag ₈ SnZ ₆ (where Z is S or Se) as a main component and having a particle size of 20 nm or less can be obtained relatively easily.

  In the 1st and 2nd manufacturing method of the semiconductor nanoparticle of this invention, since it is already demonstrated about the alkylamine or alkenylamine which has a C4-C20 hydrocarbon group, the description is abbreviate | omitted here. What is necessary is just to set reaction temperature suitably in the range of 150-350 degreeC. In this range, the lower the temperature, the smaller the average particle size, and the higher the temperature, the larger the average particle size, but the average particle size never exceeds 20 nm. In addition, the reaction time may be appropriately set depending on the simple substance used, the kind of the compound, and the reaction temperature, but it is usually preferable to set in the range of several seconds to several hours, and in the range of 1 to 60 minutes. More preferred. In addition, when semiconductor nanoparticles are obtained by dissolving the precipitate collected from the suspension obtained after heating and stirring in an organic solvent, it is preferable to use, for example, chloroform, toluene, hexane, n-butanol and the like as the organic solvent. Alternatively, the precipitate recovered from the suspension may be washed with a lower alcohol (for example, methanol or ethanol) and then dissolved in the above organic solvent, and the precipitate may be separated to obtain a semiconductor nanoparticle solution.

1. Ag ₈ SnS ₆ nanoparticles (1) Synthesis of Sn (S ₂ CNEt ₂ ) ₄ complex 50 cm ^{3 of} 0.30 moldm ⁻³ sodium N, N-diethyldithiocarbamate trihydrate ethanol solution was prepared (referred to as solution A). . 50 cm ^{3 of} 0.05 moldm ⁻³ tin (IV) chloride pentahydrate ethanol solution was prepared (referred to as solution B). While stirring in a water bath at 30 ° C., solution B was slowly added to solution A and stirred for 30 minutes. The precipitate was collected by centrifugation, washed 5 times with water and twice with ethanol. After drying, the precipitate was dissolved in chloroform, and the precipitate was removed by centrifugation. Chloroform was removed with an evaporator and dried to obtain Sn (S ₂ CNEt ₂ ) ₄ .

(2) Synthesis and characteristics of Ag ₈ SnS ₆ nanoparticles -Part 1
With respect to 0.12 mmol of commercially available Ag (S ₂ CNEt ₂ ), Sn (S ₂ CNEt ₂ ) ₄ is used in a molar ratio of a metal source of Ag: Sn = 8: x (x = 0 (Comparative Example 1), 0). .5 (Comparative Example 2), 1 (Example 1), 2 (Example 2), 4 (Example 3), 8 (Example 4)), oleylamine 3.0 cm ³ , micro stirrer At the same time, it was put into a test tube, and the inside of the test tube was filled with nitrogen gas. The test tube was set on a hot stirrer, heated and stirred at 300 ° C. for 5 minutes, and then air-cooled to room temperature to obtain a thermal decomposition product (suspension) of the complex. About 5 cm ³ of ethanol was added to this suspension, and the precipitate was collected by centrifugation. The obtained precipitate was washed twice with ethanol, dispersed in 3 cm ³ of hexane, and separated by centrifugation to obtain a hexane solution of oleylamine-modified Ag ₈ SnS ₆ nanoparticles. A schematic diagram at this time is shown in FIG.

The XRD patterns of Comparative Examples 1 and 2 and Examples 1 to 4 are shown in FIG. 2, the absorption spectrum is shown in FIG. 3, and the graph showing the relationship between the Sn charging ratio x and the ratio of metal atoms is shown in FIG. From the XRD pattern of FIG. 2, when the value of x is 1 or more (Examples 1 to 4), the obtained particles showed a diffraction pattern attributed to orthorhombic Ag ₈ SnS ₆ . On the other hand, the XRD pattern of the particles produced at x = 0 (Comparative Example 1) well matched the diffraction pattern of Ag ₂ S. The particles produced at x = 0.5 (Comparative Example 2) showed diffraction patterns derived from both Ag ₈ SnS ₆ and Ag ₂ S, and it was found that a mixture of these was formed. The absorption spectrum shown in FIG. 3 was the same curve for particles having an x value of 1 or more (Examples 1 to 4), and the absorption edge wavelength on the long wavelength side was 920 nm. When the band gap of the obtained particles was estimated from the absorption edge wavelength, it was 1.35 eV, which was in good agreement with the value reported for bulk Ag ₈ SnS ₆ (1.28-1.43 eV). In FIG. 4, in any particle having an x value of 1 or more (Examples 1 to 4), the content ratio of Ag and Sn in the particle is the theoretical ratio of Ag ₈ SnS ₆ (Ag: Sn = 0.89: 0). .11). From the above results, it was found that Ag ₈ SnS ₆ can be produced by setting the value of x to 1 or more.

TEM images of Ag ₈ SnS ₆ nanoparticles of Examples 1 to 4 are shown in FIG. 5, and a graph showing the relationship between the Sn charging ratio x and the particle diameter is shown in FIG. From the TEM image of FIG. 5, it was found that the obtained particles were spherical nanoparticles. When the particle size and its distribution were determined (FIG. 6), the average particle size of Ag ₈ SnS ₆ nanoparticles increased from 7.5 nm (standard deviation: 2.1 nm) to 15 when x = 1 was increased to x = 8. It was found to increase to 4 nm (standard deviation: 3.1 nm). The standard deviation is indicated by the error bar in FIG. 6, and it can be seen that all are 30% or less of the average particle size, and nanoparticles having a relatively narrow particle size distribution are generated. Table 1 summarizes the synthesis conditions and characteristics of Comparative Examples 1 and 2 and Examples 1 to 4.

(3) Synthesis and characteristics of Ag ₈ SnS ₆ nanoparticles -Part 2
As described above. According to the synthesis method of (2), the Sn charging ratio was fixed at x = 2, and the reaction temperature was 150 ° C. (Example 5), 200 ° C. (Example 6), 250 ° C. (Example 7), 300 ° C. Example 2), nanoparticles were synthesized at 350 ° C. (Example 8). FIG. 7 shows the XRD pattern of the obtained particles, FIG. 8 shows the absorption spectrum, and FIG. 9 shows a graph showing the relationship between the reaction temperature and the ratio of metal atoms. From the XRD pattern of FIG. 7, the obtained particles showed only a diffraction pattern attributed to orthorhombic Ag ₈ SnS _{6 under} any conditions. The absorption spectrum shown in FIG. 8 was the same when the reaction temperature was 150 to 350 ° C., and the absorption wavelength on the long wavelength side was about 920 nm. Also from Figure 9, the content of Ag and Sn in the reaction temperature were obtained at 150 to 350 ° C. particles may coincide with the theoretical ratio of _{Ag 8 SnS 6, Ag 8 SnS} 6 nanoparticles are generated I understood it. From these facts, it can be seen that Ag ₈ SnS ₆ nanoparticles can be synthesized without generating impurities such as Ag ₂ S at a reaction temperature of 150 ° C. or higher.

TEM images of the Ag ₈ SnS ₆ nanoparticles of Examples 5 to 8 and Example 2 are shown in FIG. 10, and a graph showing the relationship between the reaction temperature and the particle size is shown in FIG. FIG. 11 shows that the average particle size increases from 6.8 nm to 13 nm as the reaction temperature increases from 150 ° C. to 350 ° C. Moreover, although the standard deviation is shown by the error bar in FIG. 11, it is found that all are 30% or less of the average particle diameter, and nanoparticles having a relatively narrow distribution are generated. Table 2 summarizes the synthesis conditions and characteristics of Examples 5 to 8 and Example 2.

From the above, the particle size of the Ag ₈ SnS ₆ nanoparticles is set to _6. by appropriately setting the synthesis conditions so that the Sn charging ratio x is 1 or more and the reaction temperature is in the range of 150 ° C. to 350 ° C. It can be seen that it can be freely controlled in the range of 8 to 15.4 nm.

(4) Fabrication of nanoparticle-supported ZnO nanorod electrode (Ag ₈ SnS ₆ / ZnO NR) ZnO nanorods (rod length: 3.6 μm) are oriented almost perpendicularly to the fluorine-doped tin oxide (FTO) substrate and densely packed A supported ZnO nanorod substrate (ZnO NR substrate) was prepared according to a previous report (RSC Adv., Vol. 2, p552-559 (2012)). The Ag ₈ SnS ₆ nanoparticles used were prepared under the conditions that the Sn charging ratio x = 2 and the reaction temperature was 200 ° C., and the absorbance at a wavelength of 500 nm was 1.5 (optical path length 0.1 cm). Ag ₈ SnS ₆ nanoparticles were dissolved in hexane. The Ag ₈ SnS ₆ nanoparticles were supported on the ZnO NR substrate by dip coating. The ZnO NR substrate was immersed in an Ag ₈ SnS ₆ hexane solution for 10 seconds. Subsequently, the substrate was taken out from the Ag ₈ SnS ₆ nanoparticle solution and dried by blowing dry air. By repeating this dip coating 10 times, Ag ₈ SnS ₆ nanoparticles were densely supported on the ZnO NR substrate. The obtained substrate was heated under reduced pressure at 200 ° C. for 10 minutes to produce an Ag ₈ SnS ₆ nanoparticle-supported ZnO nanorod electrode (Ag ₈ SnS ₆ / ZnO NR, Example 9).

Further, ethylenediamine (EDA) was used as a crosslinking agent, and the supported Ag ₈ SnS ₆ nanoparticles were cross-linked to firmly fix the nanoparticles to the ZnO NR substrate. After dip-coating Ag ₈ SnS ₆ nanoparticles once on a ZnO NR substrate, the substrate was immersed in a 0.1 moldm ⁻³ EDA ethanol solution for 5 seconds, so that the supported Ag ₈ SnS ₆ nanoparticles and ZnO NR, or The Ag ₈ SnS ₆ nanoparticles were crosslinked with EDA. The substrate after the immersion was washed with ethanol to remove excess EDA, and then dried. The operation of supporting the Ag ₈ SnS ₆ nanoparticles on the substrate by dip coating and cross-linking between particles by dipping in an EDA solution was repeated 10 cycles, and then the particles were cross-linked by heating under reduced pressure at 200 ° C. for 10 minutes. An Ag ₈ SnS ₆ nanoparticle-supported ZnO nanorod electrode (EDA-Ag ₈ SnS ₆ / ZnO NR, Example 10) was prepared.

The diffuse reflection spectra of the electrodes of Examples 9 and 10 are shown in FIGS. 12 and 13, respectively. By supporting Ag ₈ SnS ₆ nanoparticles, the value of (100-R) (where R represents reflectance) is increased in the absorption wavelength region of 900 nm or less, compared with the case of ZnO NR alone, and ZnO It was found that the Ag ₈ SnS ₆ nanoparticles supported on the NR effectively absorb light having a wavelength of visible to near infrared. In particular, when the wavelength is 700 nm or less, the value of (100-R) is 90% or more, and it can be seen that Ag ₈ SnS ₆ nanoparticles of an amount sufficient to absorb visible light are supported on the electrode.

(5) Photoelectrochemical measurement of Ag ₈ SnS ₆ / ZnO NR substrate Using Ag / AgCl as a reference electrode, a platinum wire as a counter electrode, and using the electrode of Example 9 or Example 10 as a working electrode, a triode cell was assembled. . An acetonitrile solution containing 0.1 mold ^{3 -3} LiClO ₄ and 0.1 mold ^{3 -3} triethanolamine was used as the electrolyte solution. Triethanolamine was used as a hole trapping agent. As a light source, 300 W Xe lamp light (irradiation light intensity: 200 mWcm ⁻² , irradiation light wavelength> 500 nm) obtained by cutting light having a wavelength of 500 nm or less was used, and a nanoparticle-supporting electrode (electrode area: 0.79 cm ² ) by a potentiostat. The sample was irradiated with light while applying a potential. By sweeping the electrode potential of the nanoparticle-carrying electrode as the working electrode in the negative potential direction, current-potential curves during light irradiation and dark time shown in FIGS. 14 and 15 were obtained. From the graphs at the time of light irradiation in FIGS. 14 and 15, the anode photocurrent was observed when any of the electrodes of Examples 9 and 10 was used, and both electrodes showed characteristics similar to those of the n-type semiconductor.

Moreover, + 0.5Vvs. The nanoparticle-carrying electrode to which a potential of Ag / AgCl was applied was irradiated with monochromatic light through a monochromator, and the ratio of the number of electrons (IPCE) obtained as the photocurrent with respect to the number of incident photons was determined. FIG. 16 shows a graph of the irradiation light wavelength dependency (IPCE spectrum) of IPCE. In FIG. 16, since the rising wavelength of IPCE coincided well with the absorption edge wavelength of the Ag ₈ SnS ₆ nanoparticles used, it can be seen that the Ag ₈ SnS ₆ nanoparticles are effectively acting as a photosensitizer. It is suggested. However, the IPCE greatly differed depending on the presence or absence of the crosslinking agent, and the electrode of Example 9 that did not use the crosslinking agent showed a larger IPCE value at any wavelength. Further, from FIG. 14, the rising potential of the anode photocurrent also varies depending on the presence or absence of the cross-linking agent, and +0.25 Vvs. For the electrode of Example 10 with Ag / AgCl, crosslinker, -0.1 Vvs. Ag / AgCl. These results suggest that the presence of the crosslinking agent EDA greatly changed the photoelectrochemical characteristics of the Ag ₈ SnS ₆ nanoparticle-supported ZnO nanorod electrode.

2. Ag ₈ SnSe ₆ nanoparticles (1) Synthesis of Ag ₈ SnSe ₆ nanoparticles 0.12 mmol of silver acetate (I), 0.03 mmol of tin (IV) acetate, molar ratio of selenourea Ag: Sn: Se = 8: 2: 10 ) Was taken into a test tube together with oleylamine 3.0 cm ³ and a micro stir bar, and the inside of the test tube was filled with nitrogen gas. The test tube was set on a hot stirrer, heated and stirred at 250 ° C. for 5 minutes, and then cooled to room temperature to obtain a suspension. About 5 cm ³ of ethanol was added to this suspension, and the precipitate was collected by centrifugation. The resulting precipitate was washed twice with ethanol and then dispersed in 3 cm ³ of hexane. The aggregates and large particles were separated as precipitates by centrifugation to obtain a hexane solution of oleylamine-modified Ag ₈ SnSe ₆ nanoparticles (Example 11).

(2) Features of Ag ₈ SnSe ₆ Nanoparticles FIG. 17 shows the XRD pattern of the nanoparticles of Example 11, and FIG. 18 shows the absorption spectrum. From the XRD pattern of FIG. 17, the nanoparticles of Example 11 showed a diffraction pattern attributed to cubic Ag ₈ SnSe ₆ . Further, from the absorption edge wavelength (1350 nm) of the absorption spectrum of FIG. 18, the band gap of the obtained nanoparticles was estimated to be 0.92 eV. This value is larger than the value (0.83 eV) reported for bulk Ag ₈ SnSe ₆ , suggesting that the quantum size effect is manifested.

A TEM image of the nanoparticles of Example 11 is shown in FIG. 19, and the particle size distribution is shown in FIG. From FIG. 20, it was found that nanoparticles having an average particle diameter of 8.7 nm (standard deviation 2.3 nm) were obtained. Composition analysis by EDX, the composition of the obtained particles Ag: Sn: Se = 52: 7: is 41, the theoretical composition Ag: Sn: Se = 53: 7: 40 and showed good agreement, Ag ₈ It was found that SnSe ₆ nanoparticles were produced.

Claims (7)

Ag ₈ SnZ ₆ (where, Z is S or Se) are particles composed mainly of state, and are the particle size 20nm or less, the surface of the particles composed mainly of the Ag ₈ SNZ ₆ is 4 carbon Semiconductor nanoparticles modified with alkylamines or alkenylamines having 20 hydrocarbon groups . Absorption edge on the longer wavelength side of the absorption spectrum is 800nm or more, the semiconductor nanoparticles according to claim 1. The semiconductor nanoparticle carrying | support electrode which carry | supported the semiconductor nanoparticle of Claim 1 or 2 on the porous metal oxide electrode support | carrier. The semiconductor nanoparticle carrying | support electrode of Claim 3 whose absorption edge of the long wavelength side of an IPCE spectrum is 800 nm or more.   The molar ratio of the metal source is Ag: Sn = 8: x (Z), where Z (where Z is S or Se) and the Ag complex having a ligand having a ligand and the Sn complex having the ligand. However, it is placed in an alkylamine or alkenylamine having a hydrocarbon group having 4 to 20 carbon atoms so that x = 1 to 8), and heated and stirred at 150 to 350 ° C. A method for producing semiconductor nanoparticles, comprising collecting a precipitate and dissolving the precipitate in an organic solvent to obtain a solution of semiconductor nanoparticles. The ligand is a dialkyldithiocarbamic acid;
The manufacturing method of the semiconductor nanoparticle of Claim 5 .   Ag salt, Sn salt, and thiourea or selenourea have a molar ratio of Ag: Sn: S (or Se) = 8: x: y (where x = 1 to 8, y = 1 to 60). Into an alkylamine or alkenylamine having a hydrocarbon group having 4 to 20 carbon atoms, the mixture is heated and stirred at 150 to 350 ° C., and the precipitate is recovered from the resulting suspension, and the precipitate is used as an organic solvent. A method for producing semiconductor nanoparticles, which is obtained by dissolving to obtain a solution of semiconductor nanoparticles.