Fine fluorescent-material particles, process for producing fine fluorescent-material particles, thin fluorescent-material film, wavelength conversion film, wavelength conversion device, and solar cell

Abstract

A luminescent substance particle includes BaSnO.sub.3:Zn having a perovskite-type structure, a content of Zn (zinc) being more than 0.0% by mass and less than 8.0% by mass. Alternatively, a luminescent substance particle includes BaSnO.sub.3:Mg having a perovskite-type structure, a content of Mg (magnesium) being more than 0.0% by mass and less than 0.1% by mass.

Claims

1. A luminescent substance particle comprising BaSnO.sub.3:Mg having a perovskite-type structure, wherein a content of Mg (magnesium) is more than 0.0% by mass and less than 0.1% by mass, and wherein the luminescent substance particle has a particle diameter of 100 nm or less.

2. The luminescent substance particle according to claim 1, wherein the luminescent substance particle exhibits an internal quantum efficiency of more than 50%.

3. A method for producing the luminescent substance particle according to claim 1, comprising a reaction step of carrying out a reaction of a Ba (barium) source, a Sn (stannum) source, and a Mg (magnesium) source to obtain the luminescent substance particle, wherein amounts of Ba, Sn, and Mg are controlled in a manner that the amounts of Sn and Ba are equivalent to each other by mole, and the amount of Mg is more than 0.000% by mole and less than 1.198% by mole per 100% by mole of Sn in the Sn source.

4. A luminescent substance film comprising the luminescent substance particle according to claim 1.

5. A wavelength conversion film for converting a light in an ultraviolet region to a light in an infrared region, comprising a luminescent substance particle comprising BaSnO.sub.3:Mg having a perovskite-type structure, wherein a content of Mg (magnesium) is more than 0.0% by mass and less than 0.1% by mass.

6. A wavelength conversion device comprising: a substrate; and the wavelength conversion film according to claim 5 formed on the substrate.

7. The wavelength conversion device according to claim 6, wherein the substrate is a flexible resin sheet or a composite sheet containing a resin and an inorganic material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a view for illustrating a crystal structure of luminescent substance particles produced by methods for a luminescent substance particle according to first and second embodiments of the present invention;

(2) FIG. 2 is a cross-sectional view of a luminescent substance film according to an embodiment of the present invention formed on a substrate;

(3) FIG. 3 is a cross-sectional view of a wavelength conversion film according to an embodiment of the present invention formed on a quartz glass;

(4) FIG. 4 is a flow chart of an example of a method for producing the wavelength conversion film;

(5) FIG. 5 is a cross-sectional view of a wavelength conversion device according to an embodiment of the present invention;

(6) FIG. 6 is a cross-sectional view of a main portion of a solar battery according to an embodiment of the present invention;

(7) FIG. 7A is an XRD pattern of a luminescent substance particle of Sample 1, and FIG. 7B is a photograph of a microstructure of the luminescent substance particle of Sample 1 taken by a TEM (transmission electron microscope) (hereinafter referred to simply as the TEM microstructure);

(8) FIG. 8A is a graph showing results of Samples 4 to 8, the x-axis representing added Zn amount (% by mole) per 1 mol of material, and the y-axis representing Zn content (% by mass), and FIG. 8B is a graph showing results of Samples 11 to 16, the x-axis representing added Mg amount (% by mole) per 1 mol of material, and the y-axis representing Mg content (% by mass);

(9) FIG. 9 is a fluorescence spectrum of the luminescent substance particle of Sample 1;

(10) FIG. 10 is a graph showing change of internal quantum efficiency with respect to Zn concentration (Zn content);

(11) FIG. 11 is a graph showing change of internal quantum efficiency with respect to Mg concentration (Mg content); and

(12) FIG. 12 is a cross-sectional view of a main portion of a solar battery according to Comparative Example 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(13) Several embodiments of a luminescent substance particle and a production method of the luminescent substance particle will be described below with reference to FIGS. 1 to 12. It should be noted that, in this description, a numeric range of A to B includes both the numeric values A and B as the lower limit and upper limit values.

(14) (Luminescent Substance Particle)

(15) A luminescent substance particle according to a first embodiment (hereinafter referred to as the first luminescent substance particle) has BaSnO.sub.3:Zn having a perovskite-type structure, and contains more than 0.0% by mass and less than 8.0% by mass of Zn (zinc). Therefore, the first luminescent substance particle can exhibit an internal quantum efficiency of more than 50%, and thus can act to improve a power generation efficiency of a solar battery or the like and to reduce a production cost.

(16) The Zn content is preferably not less than 0.005% by mass and not more than 3.000% by mass, and more preferably not less than 0.01% by mass and not more than 1.30% by mass.

(17) A luminescent substance particle according to a second embodiment (hereinafter referred to as the second luminescent substance particle) has BaSnO.sub.3:Mg having a perovskite-type structure, and contains more than 0.0% by mass and less than 0.1% by mass of Mg (magnesium). Therefore, the second luminescent substance particle can exhibit an internal quantum efficiency of more than 50%, and thus can act to improve a power generation efficiency of a solar battery or the like and to reduce a production cost.

(18) The Mg content is preferably not less than 0.0005% by mass and not more than 0.0300% by mass, and more preferably not less than 0.001% by mass and not more than 0.010% by mass.

(19) The luminescent substance particles have a perovskite-type crystal structure shown in FIG. 1. In the crystal structure, the Ba (barium) atoms are located at the corner positions, the Sn (stannum) atom is located at the body center position, and the O (oxygen) atoms are located at the face center positions around the body center Sn. Zn or Mg may be incorporated into the perovskite-type crystal structure at either a substitutional site or interstitial site.

(20) A method for producing the first and second luminescent substance particles contains the step of carrying out a reaction of a Ba (barium) source and a Sn (stannum) source.

(21) In production of the first luminescent substance particle, it is preferred that the amounts of Ba, Sn, and Zn are controlled in such a manner that the amounts of Sn and Ba are equivalent to each other by mole and the amount of Zn is more than 0.000% by mole and less than 40.262% by mole per 100% by mole of Sn in the Sn source. The Zn amount is more preferably not less than 0.025% by mole and not more than 15.098% by mole, further preferably not less than 0.050% by mole and not more than 6.543% by mole, per 100% by mole of Sn in the Sn source.

(22) In production of the second luminescent substance particle, it is preferred that the amounts of Ba, Sn, and Mg are controlled in such a manner that the amounts of Sn and Ba are equivalent to each other by mole and the amount of Mg is more than 0.000% by mole and less than 1.198% by mole per 100% by mole of Sn in the Sn source. The Mg amount is more preferably not less than 0.006% by mole and not more than 0.359% by mole, further preferably not less than 0.012% by mole and not more than 0.120% by mole, per 100% by mole of Sn in the Sn source.

(23) In the method for producing the first and second luminescent substance particles, for example, a plasma synthesis process, a microwave hydrothermal synthesis process, a supercritical hydrothermal synthesis process using a titanium alloy container, a spray pyrolysis synthesis process, or the like may be performed in the step of carrying out the reaction.

(24) In the plasma synthesis process, a BaCO.sub.3 powder is used as the Ba source, and a SnO.sub.2 powder is used as the Sn source, in such a manner that the amount of Sn is equivalent to the amount of Ba by mole. The sources and ethanol are added into an agate mortar, and the sources are ground and mixed until the mixture loses fluidity due to evaporation of the ethanol. Then, the resultant is dried by a dryer or the like to thereby obtain a mixture powder as a starting material for the plasma synthesis. The mixture powder is introduced into a plasma chamber at a high temperature to thereby produce a BaSnO.sub.3 particle powder.

(25) In the microwave hydrothermal synthesis process, Ba(OH).sub.2 is used as the Ba source, and a SnO.sub.2 sol is used as the Sn source. The sources and an appropriate amount of water are added together with a stirrer chip made of TEFLON (trademark) into a pressure-resistant resin container having an inner coating of TEFLON (trademark), and the container is sealed. The inside of the container is heated to 270 C. by irradiating with a microwave at a maximum output of 600 W while stirring the mixture liquid in the container. The mixture liquid is maintained in the hydrothermal state for at least 10 hours to thereby obtain an aqueous solution containing BaSnO.sub.3 particles dispersed. The aqueous solution is subjected to a centrifugation treatment, the supernatant is removed, pure water is added to the resultant, and this is subjected to the centrifugation treatment again. The water addition and the centrifugation treatment are repeated, and the resultant is dried by a dryer to thereby obtain a BaSnO.sub.3 particle powder. The Ba source and the Sn source are not limited to the above compounds, and may be selected from chlorides, nitric acid compounds, and the like.

(26) In the supercritical hydrothermal synthesis process using the titanium alloy container, Ba(OH).sub.2 is used as the Ba source, and a SnO.sub.2 sol is used as the Sn source. The sources and an appropriate amount of water are added into a pressure-resistant container made of a titanium alloy, and the container is sealed. The mixture is heated to 400 C. by a dryer or the like, and is maintained in the supercritical hydrothermal state for at least 1 hour, to thereby obtain an aqueous solution containing BaSnO.sub.3 particles dispersed. The aqueous solution is subjected to a centrifugation treatment, the supernatant is removed, pure water is added to the resultant, and this is subjected to the centrifugation treatment again. The water addition and the centrifugation treatment are repeated, and the resultant is dried by a dryer to thereby obtain a BaSnO.sub.3 particle powder. The Ba source and the Sn source are not limited to the above compounds, and may be selected from chlorides, nitric acid compounds, and the like.

(27) In the spray pyrolysis synthesis process, BaCl.sub.2 is used as the Ba source, and SnCl.sub.2 is used as the Sn source, in such a manner that the amount of Sn is equivalent to the amount of Ba by mole. The sources are dissolved in water to prepare an aqueous solution of a starting material. The aqueous solution is sprayed and introduced into a reaction container at a high temperature to thereby produce a BaSnO.sub.3 particle powder. The Ba source and the Sn source are not limited to the above compounds, and may be selected from hydroxides, nitric acid compounds, and the like.

(28) In the spray pyrolysis synthesis process, a salt-assisted spray pyrolysis synthesis may be carried out. The salt-assisted spray pyrolysis synthesis is characterized by the following steps. An inorganic compound of an element other than the elements for the target material particle is dissolved in a solution containing the sources, and this solution is subjected to the spray pyrolysis to thereby prepare an agglomerated particle. The structure of the agglomerated particle is such that a primary particle containing the elements for the target material is located inside the inorganic compound. Then, the inorganic compound is separated from the agglomerated particle to thereby produce the primary particle.

(29) The composition of the luminescent substance particle may be measured by an energy dispersive X-ray analyzer. The crystal structure of the luminescent substance particle may be measured by a powder X-ray diffractometer (XRD). The particle diameter of the luminescent substance particle may be measured by observation using an electron microscope such as a transmission electron microscope (TEM).

(30) In this embodiment, the particle diameter of the luminescent substance particle is preferably 100 nm or less although it may be of the order of micrometers.

(31) The particle diameter of the luminescent substance particle may be measured by observation using an electron microscope such as a transmission electron microscope (TEM). The particle diameter of the luminescent substance particle is the diameter of the particle that is not subjected to a secondary treatment such as a grinding treatment or a classification treatment. The average particle diameter may be the average of the particle diameters of the luminescent substance particles contained in the observation area of the electron microscope.

(32) (Luminescent Substance Film)

(33) A luminescent substance film 50 shown in FIG. 2 according to an embodiment of the present invention contains the above described luminescent substance particle of the embodiment. The method for forming the luminescent substance film 50 is not particularly limited and may be appropriately selected depending on the intended use, as long as the luminescent substance film 50 contains the luminescent substance particle of the above embodiment. For example, the luminescent substance film 50 may be produced by a common method such as a spray method or a dipping method. In FIG. 2, the luminescent substance film 50 is formed on a substrate 52.

(34) (Wavelength Conversion Film)

(35) As shown in FIG. 3, a wavelength conversion film 54 according to an embodiment of the present invention contains the above described luminescent substance particle of the embodiment, and acts to convert a light 56 in the ultraviolet region to a light 58 in the infrared region. The wavelength conversion film 54 is formed, e.g., on a surface of a quartz glass 60.

(36) The wavelength conversion film 54 may be produced as follows. Thus, the luminescent substance particles are dispersed in a liquid phase, and application of the dispersion is performed to thereby produce the wavelength conversion film 54.

(37) More specifically, in Step S1 of FIG. 4, an ethanol solution is added into a container containing a powder of the luminescent substance particle. In Step S2, the luminescent substance particle powder in the container is ultrasonic-dispersed.

(38) Then, in Step S3, a polysiloxane oligomer-containing coating material, such as GLASCA HP7003 (trade name) available from JSR Corporation, is added to the container. The polysiloxane oligomer-containing coating material is a solution containing a polysiloxane oligomer derived from an alkoxysilane. The solution is applied and dried to thereby form a strong transparent coating having a main skeleton of a siloxane bond network structure (SiO).sub.n.

(39) In Step S4, the luminescent substance particle powder in the container is ultrasonic-dispersed to prepare a film-forming slurry. In Step S5, the film-forming slurry is applied to the surface of the quartz glass 60 or the like. For example, the surface is spin-coated with the film-forming slurry.

(40) In Step S6, the film-forming slurry applied to the quartz glass 60 is dried at ordinary temperature. By such drying, the liquid phase is hardened while incorporating the luminescent substance particle therein. Consequently, a strong wavelength conversion film 54 thus-obtained has the main skeleton of the siloxane bond network structure (SiO).sub.n as described above.

(41) (Wavelength Conversion Device)

(42) As shown in FIG. 5, a wavelength conversion device 70 according to an embodiment of the present invention has a substrate 72, and further has the above-described wavelength conversion film 54 formed on one main surface of the substrate 72. As the substrate 72, the above quartz glass 60, a soda glass for a solar battery, etc. may be used.

(43) Alternatively, for example, as the substrate 72, a flexible transparent resin sheet, a composite sheet containing a resin and an inorganic material, or the like may be used. In this case, the substrate 72 is preferably a transparent film.

(44) (Solar Battery)

(45) As shown in FIG. 6, a main portion of a solar battery 80 according to an embodiment of the present invention has a plurality of power generation cells 82 arranged in a plane, a sealing layer 84 formed so as to cover the power generation cells 82, a glass 86 formed on the sealing layer 84, and the wavelength conversion film 54 formed on a front surface of the glass 86.

(46) For example, the sealing layer 84 may be composed of a light-transmitting sealant resin such as a polyethylene-polyvinyl acetate copolymer (EVA). The sealing layer 84 preferably has a light transmittance of 80% or more in a wavelength region of 200 to 800 nm. The glass 86 is a protection glass, and generally uses a soda glass.

(47) In another example of the solar battery 80 (not shown), the wavelength conversion film 54 may be formed on a front surface or a rear surface of at least one component of the solar battery 80. Alternatively, the wavelength conversion device 70 may be disposed between a plurality of components of the solar battery 80 or on a light incident surface of the solar battery 80.

(48) In general, the wavelength conversion film 54 or the wavelength conversion device 70 may be located between the power generation cells 82 and the solar light incident surface. Incidentally, the glass 86 (the protection glass, generally containing the soda glass) and the sealing layer (containing a resin such as EVA) absorb a part of an ultraviolet light. Therefore, it is more preferred that the wavelength conversion film 54 is arranged closer to the solar light incident surface.

(49) As described above, in Japanese Laid-Open Patent Publication No. 2013-004806, the wavelength conversion layer contains an organic material. Thus, the document gives a suggestion that it is not preferable to form the wavelength conversion layer on the outermost surface exposed to external air. In this embodiment, since the wavelength conversion film 54 is composed of the inorganic material, the wavelength conversion film 54 can be disposed on the outermost surface. Thus, in the present invention, the formation position of the wavelength conversion film 54 or the wavelength conversion device 70 can be arbitrarily selected, and the design flexibility can be increased. In this regard, in Japanese Laid-Open Patent Publication No. 2013-004806, an ultraviolet-transmittable quartz glass is used as a protection glass. However, the quartz glass is highly costly, and therefore cannot be actually used in a solar battery.

EXAMPLES

First Example

(50) XRD patterns of luminescent substance particles of Samples 1 to 16 were evaluated. Furthermore, light emission intensities of the luminescent substance particles of Samples 1 to 16 were evaluated in the fluorescence spectra. Each fluorescence spectrum was obtained by emitting lights with various excitation wavelengths to the luminescent substance particle thereof. Furthermore, effects of Zn or Mg addition on internal quantum efficiency were evaluated.

(51) (Sample 1)

(52) A BaCO.sub.3 powder (BAH07XB available from Kojundo Chemical Lab. Co., Ltd.) was used as a Ba source, and a SnO.sub.2 powder (SNO06PB available from Kojundo Chemical Lab. Co., Ltd.) was used as a Sn source. The Ba source and the Sn source were reacted by a plasma synthesis process to thereby produce the luminescent substance particle of Sample 1. In the production of the luminescent substance particle of Sample 1, 0.010% by mole of Zn was added to 100% by mole of Sn in the Sn source. The Zn cation addition was carried out in the plasma synthesis process as follows. Zn(NO.sub.3).sub.2.6H.sub.2O (ZNH09XAG available from Kojundo Chemical Lab. Co., Ltd.) was added to and dissolved in ethanol, and the BaCO.sub.3 powder and the SnO.sub.2 powder were ground and mixed in the ethanol solution as described above, while the Zn amount per 100% by mole of Sn in the Sn source is controlled to be a specified mole ratio.

(53) (Sample 2)

(54) The luminescent substance particle of Sample 2 was produced in the same manner as Sample 1 except that 0.020% by mole of Zn was added to 100% by mole of Sn in the Sn source.

(55) (Sample 3)

(56) The luminescent substance particle of Sample 3 was produced in the same manner as Sample 1 except that 0.040% by mole of Zn was added to 100% by mole of Sn in the Sn source.

(57) (Sample 4)

(58) The luminescent substance particle of Sample 4 was produced in the same manner as Sample 1 except that 0.200% by mole of Zn was added to 100% by mole of Sn in the Sn source.

(59) (Sample 5)

(60) The luminescent substance particle of Sample 5 was produced in the same manner as Sample 1 except that 1.000% by mole of Zn was added to 100% by mole of Sn in the Sn source.

(61) (Sample 6)

(62) The luminescent substance particle of Sample 6 was produced in the same manner as Sample 1 except that 4.000% by mole of Zn was added to 100% by mole of Sn in the Sn source.

(63) (Sample 7)

(64) The luminescent substance particle of Sample 7 was produced in the same manner as Sample 1 except that 20.000% by mole of Zn was added to 100% by mole of Sn in the Sn source.

(65) (Sample 8)

(66) The luminescent substance particle of Sample 8 was produced in the same manner as Sample 1 except that 40.000% by mole of Zn was added to 100% by mole of Sn in the Sn source.

(67) (Sample 9)

(68) A Ba source and a Sn source were reacted by a plasma synthesis process to thereby produce the luminescent substance particle of Sample 9. In the production of the luminescent substance particle of Sample 9, 0.002% by mole of Mg was added to 100% by mole of Sn in the Sn source. The Mg cation addition was carried out in the plasma synthesis process as follows. Mg(NO.sub.3).sub.2.6H.sub.2O (MGH12XB available from Kojundo Chemical Lab. Co., Ltd.) was added to and dissolved in ethanol, and the BaCO.sub.3 powder and the SnO.sub.2 powder were ground and mixed in the ethanol solution as described above, while the Mg amount per 100% by mole of Sn in the Sn source is controlled to be a specified mole ratio.

(69) (Sample 10)

(70) The luminescent substance particle of Sample 10 was produced in the same manner as Sample 9 except that 0.005% by mole of Mg was added to 100% by mole of Sn in the Sn source.

(71) (Sample 11)

(72) The luminescent substance particle of Sample 11 was produced in the same manner as Sample 9 except that 0.010% by mole of Mg was added to 100% by mole of Sn in the Sn source.

(73) (Sample 12)

(74) The luminescent substance particle of Sample 12 was produced in the same manner as Sample 9 except that 0.040% by mole of Mg was added to 100% by mole of Sn in the Sn source.

(75) (Sample 13)

(76) The luminescent substance particle of Sample 13 was produced in the same manner as Sample 9 except that 0.064% by mole of Mg was added to 100% by mole of Sn in the Sn source.

(77) (Sample 14)

(78) The luminescent substance particle of Sample 14 was produced in the same manner as Sample 9 except that 0.200% by mole of Mg was added to 100% by mole of Sn in the Sn source.

(79) (Sample 15)

(80) The luminescent substance particle of Sample 15 was produced in the same manner as Sample 9 except that 0.500% by mole of Mg was added to 100% by mole of Sn in the Sn source.

(81) (Sample 16)

(82) The luminescent substance particle of Sample 16 was produced in the same manner as Sample 9 except that 3.000% by mole of Mg was added to 100% by mole of Sn in the Sn source.

(83) The details, the Zn and Mg contents, and the internal quantum efficiencies of Samples 1 to 16 are shown in Tables 1 and 2.

(84) TABLE-US-00001 TABLE 1 Added Zn amount per 100% by mole of Sn in Sn Internal quantum source Zn content efficiency (% by mole) (% by mass) (%) Sample 1 0.010 0.002 52 Sample 2 0.020 0.004 54 Sample 3 0.040 0.008 59 Sample 4 0.200 0.030 65 Sample 5 1.000 0.180 66 Sample 6 4.000 0.800 62 Sample 7 20.000 4.230 53 Sample 8 40.000 8.050 49

(85) TABLE-US-00002 TABLE 2 Added Mg amount per 100% by mole of Sn in Sn Internal quantum source Mg content efficiency (% by mole) (% by mass) (%) Sample 9 0.002 0.0002 51 Sample 10 0.005 0.0004 53 Sample 11 0.010 0.0010 59 Sample 12 0.040 0.0020 62 Sample 13 0.064 0.0060 61 Sample 14 0.200 0.0150 58 Sample 15 0.500 0.0460 52 Sample 16 3.000 0.2500 49
<Evaluation: XRD Pattern and TEM Microstructure>
(Sample 1)

(86) A typical XRD pattern of the luminescent substance particle of Sample 1 is shown in FIG. 7A. The XRD pattern is approximately equal to that of the cubic crystal BaSnO.sub.3. A TEM microstructure of the luminescent substance particle of Sample 1 is shown in FIG. 7B. As evident from FIG. 7B, it was confirmed that the luminescent substance particles having particle diameters of about 10 to 40 nm were formed.

(87) (Samples 2 to 16)

(88) XRD patterns and TEM microstructures of Samples 2 to 16 were similar to those of Sample 1 (FIGS. 7A and 7B).

(89) <Evaluation: Zn Content>

(90) The Zn contents of Samples 1 to 3 were lower than the detection limit of the FP method using fluorescent X-ray spectra. Therefore, the Zn contents were estimated as follows. As shown in FIG. 8A, the data of Samples 4 to 8 were plotted on an x-y graph. The x-axis represents added Zn amount (% by mole) per 1 mol of Sn in the Sn source, and the y-axis represents Zn content (% by mass). A line equation (y=0.2033x, R.sup.2=0.9993) was obtained from the plotted data by a least-square method, and the Zn contents corresponding to the added Zn amounts of Samples 1 to 3 were determined using the line equation (R.sup.2: coefficient of determination that indicates the goodness of fit of the line equation for the data of Samples 4 to 8).

(91) (Samples 1 to 3)

(92) The Zn contents of Samples 1, 2, and 3 determined based on the above line equation were 0.002%, 0.004%, and 0.008% by mass, respectively.

(93) (Sample 4)

(94) Concerning the Zn content of Sample 4, a non-standard semi-quantitative analysis of the obtained fluorescent X-ray spectrum was carried out based on an FP method. As a result, the Zn content of Sample 4 was 0.030% by mass.

(95) (Samples 5 to 8)

(96) Samples 5, 6, 7, and 8 had Zn contents of 0.180%, 0.800%, 4.230%, and 8.050% by mass respectively.

(97) <Evaluation: Mg Content>

(98) Similarly to the Zn contents of Samples 1 and 2, the Mg contents of Samples 9 and 10 were lower than the detection limit of the FP method using fluorescent X-ray spectra. Therefore, the Mg contents were estimated as follows. As shown in FIG. 8B, the data of Samples 11 to 16 were plotted on an x-y graph. The x-axis represents added Mg amount (% by mole) per 1 mol of Sn in the Sn source, and the y-axis represents Mg content (% by mass). A line equation (y=0.0835x, R.sup.2=0.9995) was obtained from the plotted data by a least-square method, and the Mg contents corresponding to the added Mg amounts of Samples 9 and 10 were determined using the line equation (R.sup.2: coefficient of determination that indicates the goodness of fit of the line equation for the data of Samples 11 to 16).

(99) (Samples 9 and 10)

(100) The Mg contents of Samples 9 and 10 determined based on the above line equation were 0.0002% and 0.0004% by mass respectively.

(101) (Sample 11)

(102) Concerning the Mg content of Sample 11, a non-standard semi-quantitative analysis of the obtained fluorescent X-ray spectrum was carried out based on an FP method. As a result, Sample 11 had a Mg content of 0.0010% by mass.

(103) (Samples 12 to 16)

(104) Samples 12, 13, 14, 15, and 16 had Mg contents of 0.0020%, 0.0060%, 0.0150%, 0.0460%, and 0.2500% by mass respectively.

(105) <Evaluation: Internal Quantum Efficiency>

(106) (Sample 1)

(107) An internal quantum efficiency of a specimen of the luminescent substance particle of Sample 1 (a specimen of Sample 1) was measured by using a spectrofluorophotometer (FP-8600 available from JASCO Corporation) and a 60-mm integrating sphere. In the internal quantum efficiency measurement, the specimen of Sample 1 was irradiated with an excitation light having a wavelength of 360 nm.

(108) As shown in FIG. 9, in the internal quantum efficiency measurement, a fluorescence spectrum peak with a center wavelength of approximately 900 nm was observed under the excitation light having the wavelength of 360 nm. The following Samples 2 to 16 exhibited a similar peak.

(109) As a result of the measurement, the specimen of Sample 1 had an internal quantum efficiency of 52%.

(110) (Samples 2 to 8)

(111) The internal quantum efficiencies of the luminescent substance particle specimens of Samples 2 to 8 were measured in the same manner as Sample 1. As a result, as shown in Table 1, Samples 2 to 8 had internal quantum efficiencies of 54%, 59%, 65%, 66%, 62%, 53%, 49%, respectively.

(112) (Samples 9 to 16)

(113) The internal quantum efficiencies of the luminescent substance particle specimens of Samples 9 to 16 were measured in the same manner as Sample 1. As a result, as shown in Table 2, Samples 9 to 16 had internal quantum efficiencies of 51%, 53%, 59%, 62%, 61%, 58%, 52%, 49%, respectively.

(114) <Evaluation: Internal Quantum Efficiency With Respect to Zn Content>

(115) Based on the results of Samples 1 to 8, the internal quantum efficiencies were plotted with respect to the Zn concentrations (Zn contents) to thereby obtain a characteristic curve representing the internal quantum efficiency changes with respect to the Zn concentration. The results are shown in FIG. 10.

(116) The characteristic curve shows the following properties. The internal quantum efficiency was about 50% when the Zn concentration was 0% by mass. The internal quantum efficiency was increased as the Zn concentration was increased, and the internal quantum efficiency had a peak of about 66% when the Zn concentration was about 0.1% by mass. The internal quantum efficiency was lowered as the Zn concentration was further increased, and the internal quantum efficiency was below 50% when the Zn concentration was 8.00% by mass.

(117) As is clear from the results, it is preferred that the Zn content falls within the range shown in Table 3.

(118) TABLE-US-00003 TABLE 3 Range P1 P2 P3 Internal quantum efficiency >50% 55% 60% Zn concentration Lower limit More than 0 0.005 0.010 (% by mass) Upper limit Less than 8.000 3.000 1.300

(119) Thus, when the Zn concentration is within the range P1 of more than 0% by mass and less than 8.000% by mass, the internal quantum efficiency is more than 50%. When the Zn concentration is within the range P2 of not less than 0.005% by mass and not more than 3.000% by mass, the internal quantum efficiency is 55% or more. When the Zn concentration is within the range P3 of not less than 0.010% by mass and not more than 1.300% by mass, the internal quantum efficiency is 60% or more.

(120) Furthermore, the added Zn amounts (feed mole ratios) corresponding to the three threshold values of the Zn concentration were determined using the line equation (y=0.2033x, R.sup.2=0.9993) shown in FIG. 8A. The results are shown in Table 4.

(121) TABLE-US-00004 TABLE 4 Range P1 P2 P3 Internal quantum efficiency >50% 55% 60% Added Zn amount Lower limit More than 0 0.025 0.050 (% by mole) Upper limit Less than 40.262 15.098 6.543
<Evaluation: Internal Quantum Efficiency With Respect to Mg Content>

(122) Based on the results of Samples 9 to 16, the internal quantum efficiencies were plotted with respect to the Mg concentrations (Mg contents) to thereby obtain a characteristic curve representing the internal quantum efficiency changes with respect to the Mg concentration. The results are shown in FIG. 11.

(123) The characteristic curve shows the following properties. The internal quantum efficiency was about 50% when the Mg concentration was 0% by mass. The internal quantum efficiency was increased as the Mg concentration was increased, and the internal quantum efficiency had a peak of about 63% when the Mg concentration was about 0.0035% by mass. The internal quantum efficiency was lowered as the Mg concentration was further increased, and the internal quantum efficiency was below 50% when the Mg concentration was about 0.1% by mass.

(124) As is clear from the results, it is preferred that the Mg concentration is within the range shown in Table 5.

(125) TABLE-US-00005 TABLE 5 Range P4 P5 P6 Internal quantum efficiency >50% 55% 60% Mg concentration Lower limit More than 0 0.0005 0.0010 (% by mass) Upper limit Less than 0.1000 0.0300 0.0100

(126) Thus, when the Mg concentration is within the range P4 of more than 0% by mass and less than 0.1000% by mass, the internal quantum efficiency is more than 50%. When the Mg concentration is within the range P5 of not less than 0.0005% by mass and not more than 0.0300% by mass, the internal quantum efficiency is 55% or more. When the Mg concentration is within the range P6 of not less than 0.0010% by mass and not more than 0.0100% by mass, the internal quantum efficiency is 60% or more.

(127) Furthermore, the added Mg amounts (feed mole ratios) corresponding to the three threshold values of the Mg concentration were determined using the line equation (y=0.0835x, R.sup.2=0.9995) shown in FIG. 8B. The results are shown in Table 6.

(128) TABLE-US-00006 TABLE 6 Range P4 P5 P6 Internal quantum efficiency >50% 55% 60% Added Mg amount Lower limit More than 0 0.006 0.012 (% by mole) Upper limit Less than 1.198 0.359 0.120

Second Example

Solar Battery

(129) Electric power generation amount differences were confirmed between Examples 1 to 10 and Comparative Examples 1 and 2. Furthermore, electric power generation amount increases with respect to Comparative Example 1 were confirmed in Examples 1 to 10 and Comparative Example 2.

Example 1

(130) A solar battery of Example 1 had the same structure as the solar battery 80 shown in FIG. 6. More specifically, the solar battery of Example 1 has a plurality of the power generation cells 82 arranged in a plane, the sealing layer 84 formed so as to cover the power generation cells 82, the glass 86 formed on the sealing layer 84, and the wavelength conversion film 54 formed on a surface of the glass 86. The luminescent substance particle contained in the wavelength conversion film 54 was prepared as follows. A Ba source and a Sn source were reacted by a plasma synthesis process, 0.040% by mole of Zn being added to 100% by mole of Sn in the Sn source in the same manner as Sample 3. The luminescent substance particle had a Zn content of 0.008% by mass (estimate value).

Example 2

(131) A solar battery of Example 2 was produced in the same manner as Example 1 except that the luminescent substance particle in the wavelength conversion film 54 was prepared by adding 1.000% by mole of Zn to 100% by mole of Sn in the Sn source as in Sample 5. The luminescent substance particle had a Zn content of 0.180% by mass.

Example 3

(132) A solar battery of Example 3 was produced in the same manner as Example 1 except that the luminescent substance particle in the wavelength conversion film 54 was prepared by adding 0.040% by mole of Mg to 100% by mole of Sn in the Sn source as in Sample 12. The luminescent substance particle had a Mg content of 0.0020% by mass.

Example 4

(133) A solar battery of Example 4 was produced in the same manner as Example 1 except that the luminescent substance particle in the wavelength conversion film 54 was prepared by adding 0.200% by mole of Mg to 100% by mole of Sn in the Sn source as in Sample 14. The luminescent substance particle had a Mg content of 0.0150% by mass.

Examples 5 and 6

(134) Solar batteries of Examples 5 and 6 were produced in the same manner as Examples 2 and 3 respectively except that the luminescent substance particle in the wavelength conversion film 54 was prepared as follows. A Ba source and a Sn source were reacted by a microwave hydrothermal synthesis process, wherein in Example 5, 1.000% by mole of Zn was added to 100% by mole of Sn in the Sn source, and in Example 6, 0.040% by mole of Mg was added to 100% by mole of Sn in the Sn source.

Examples 7 and 8

(135) Solar batteries of Examples 7 and 8 were produced in the same manner as Examples 2 and 3 respectively except that the luminescent substance particle in the wavelength conversion film 54 was prepared as follows. A Ba source and a Sn source were reacted by a supercritical hydrothermal synthesis process using a titanium alloy container, wherein in Example 7, 1.000% by mole of Zn was added to 100% by mole of Sn in the Sn source, and in Example 8, 0.040% by mole of Mg was added to 100% by mole of Sn in the Sn source.

Examples 9 and 10

(136) Solar batteries of Examples 9 and 10 were produced in the same manner as Examples 2 and 3 respectively except that the luminescent substance particle in the wavelength conversion film 54 was prepared as follows. A Ba source and a Sn source were reacted by a spray pyrolysis synthesis process, wherein in Example 9, 1.000% by mole of Zn was added to 100% by mole of Sn in the Sn source, and in Example 10, 0.040% by mole of Mg was added to 100% by mole of Sn in the Sn source.

Comparative Example 1

(137) As shown in FIG. 12, a solar battery of Comparative Example 1 has a plurality of the power generation cells 82 arranged in a plane, the sealing layer 84 formed on the power generation cells 82, and the glass 86 formed on the sealing layer 84.

Comparative Example 2

(138) A solar battery of Comparative Example 2 was produced in the same manner as Example 1 except that the luminescent substance particle in the wavelength conversion film 54 was prepared without adding Zn or Mg.

(139) (Evaluation)

(140) The details and the power generation amounts (mW/cm.sup.2) of Examples 1 to 10 and Comparative Examples 1 and 2 are shown in Table 7. Furthermore, the output increases (%) of Examples 1 to 10 and Comparative Example 2 are shown in Table 7. For example, the output increase of Example 1 was calculated by the equation: (power generation amount of Example 1power generation amount of Comparative Example 1)/power generation amount of Comparative Example 1.

(141) TABLE-US-00007 TABLE 7 Added element amount Internal Power Luminescent per 100% by mole of quantum generation Output substance particle Additive Sn in Sn source efficiency amount increase production method element (% by mole) (%) (mW/cm.sup.2) (%) Comp. Ex. 1 No luminescent substance particle 12.20 0 No wavelength conversion film Comp. Ex. 2 Plasma Not added 50 13.30 9.0 Ex. 1 Plasma Zn 0.040 59 13.60 11.5 Ex. 2 Plasma Zn 1.000 66 13.80 13.1 Ex. 3 Plasma Mg 0.040 62 13.70 12.3 Ex. 4 Plasma Mg 0.200 58 13.55 11.1 Ex. 5 Microwave Zn 1.000 65 13.75 12.7 hydrothermal Ex. 6 Microwave Mg 0.040 61 13.60 11.5 hydrothermal Ex. 7 Supercritical Zn 1.000 65 13.70 12.3 hydrothermal Ex. 8 Supercritical Mg 0.040 61 13.60 11.5 hydrothermal Ex. 9 Spray pyrolysis Zn 1.000 66 13.75 12.7 Ex. 10 Spray pyrolysis Mg 0.040 62 13.65 11.9

(142) The power generation amounts of Comparative Examples 1 contrast, the power generation amounts of Examples 1 to 10 were larger than those of Comparative Examples 1 and 2. In particular, the solar batteries of Examples 2, 3, and 5 to 10 had internal quantum efficiencies of more than 60% and thus exhibited excellent output increases.

(143) As is also clear from the results of Examples 2, 3, and 5 to 10, for producing the luminescent substance particle, the supercritical hydrothermal synthesis process using the titanium alloy container was preferred, the microwave hydrothermal synthesis process was more preferred, the spray pyrolysis synthesis process was further preferred, and the plasma synthesis process was most preferred.

(144) The luminescent substance particle, the luminescent substance particle production method, the luminescent substance film, the wavelength conversion film, the wavelength conversion device, and the solar battery of the present invention are not limited to the above-described embodiments, and various changes and modifications may be made therein without departing from the scope of the invention.