JP5744312B2 - Complex compound, raw material for forming semiconductor layer, method for producing semiconductor layer, and method for producing photoelectric conversion device - Google Patents

Description

  The present invention relates to a raw material for forming a semiconductor layer used for forming a semiconductor layer containing a complex compound comprising an IB group element, an IV-B group element and a VI-B group element, and an I-II-IV-VI group compound, The present invention relates to a method for producing a semiconductor layer containing an I-II-IV-VI group compound and a method for producing a photoelectric conversion element using the same.

Silicon or a compound semiconductor is used as the light absorption layer of the solar cell. Compound semiconductors include III-V group compounds such as GaAs, II-VI group compounds such as CdS and CdTe, I-III-VI group compounds such as CuInGaSe ₂ (CIGS), and Cu ₂ ZnSnS ₄ (CZTS). There are Group I-II-IV-VI compounds.

  Of these, chalcogenide-based compounds have a large light absorption coefficient, so the light absorption layer can be made thinner and high conversion efficiency has been obtained. Therefore, they are attracting attention as next-generation solar cells that replace conventional silicon. ing. Among them, the I-II-IV-VI group compounds are particularly attracting attention because they do not contain rare elements such as indium and gallium.

  For example, Non-patent Document 1 (Takeshi Kobayashi et al., “Investigation of Cu2ZnSnS4-Based Thin Film Solar Cells Using Abundant Materials”, Japanese Journal of Applied Physics , vol.44, No.1B, 2005, pp.783-787) and Non-Patent Document 2 (TK Todorov, et al., Advanced Energy Materials 22, E-156-E159 (2010)).

In Non-Patent Document 1, production of CZTS in which an Sn / Cu / ZnS laminated precursor is formed on SLG (soda lime glass) using an electron beam evaporation method, and the precursor is sulfided in a 5% H ₂ S + N ₂ atmosphere. A method is disclosed.

  Non-Patent Document 2 discloses a method for producing CZTS using a solution in which metal chalcogenide is dissolved in hydrazine.

  However, the manufacturing method of Non-Patent Document 1 has a problem in that the manufacturing cost is high because a vacuum process is used. Further, in the production method of Non-Patent Document 2, hydrazine used as a solvent is extremely toxic to the human body, and there is a risk that harmful gases such as ammonia may be generated when dissolving metal chalcogenides. Therefore, there is a problem that it is difficult to make a mass production because measures such as providing a special device are required.

  Therefore, an object of the present invention is to produce a semiconductor layer containing a I-II-IV-VI group compound by a simple method.

  The complex compound according to one embodiment of the present invention is represented by the structural formula (1).

In Structural Formula (1), M ¹ represents Cu . M ² represents Sn . R ^{1 to} R ³ each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted heterocyclic group . X ^{1 to} X ³ each independently represent S or Se . L ¹ and L ² each independently represents a ligand. Here, L ¹ and L ² may be linked to form a saturated or unsaturated ring.

The raw material for forming a semiconductor layer according to an embodiment of the present invention includes the complex compound and a II-B group compound in which the II-B group element is Zn .

  A method for producing a semiconductor layer according to an embodiment of the present invention includes a step of forming a film using the semiconductor layer forming raw material, and a semiconductor layer containing the I-II-IV-VI group compound by heating the film. The process to make.

  A method for manufacturing a photoelectric conversion device according to an embodiment of the present invention includes: a step of manufacturing a first semiconductor layer by the method for manufacturing a semiconductor layer; and a method of electrically connecting to the first semiconductor layer. Forming a second semiconductor layer having a conductivity type different from that of the first semiconductor layer.

  According to the present invention, a semiconductor layer can be easily manufactured.

It is a perspective view which shows an example of embodiment of a photoelectric conversion apparatus. It is sectional drawing of the photoelectric conversion apparatus of FIG.

  Refer to the drawings for a complex compound according to an embodiment of the present invention, a raw material for forming a semiconductor layer according to an embodiment, a method for manufacturing a semiconductor layer according to an embodiment, and a method for manufacturing a photoelectric conversion device according to an embodiment. The details will be described.

(1. Configuration of complex compound)
The complex compound according to one embodiment of the present invention is represented by the structural formula (1) (hereinafter, the complex compound represented by the structural formula (1) is also referred to as a first complex compound).

Note that in Structural Formula (1), M ¹ represents Cu among Group IB elements (also referred to as Group 11 elements). M ² represents Sn among group IV-B elements (also referred to as group 14 elements). R ^{1 to} R ³ each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted heterocyclic group . X ^{1 to} X ³ each independently represent S or Se among the chalcogen elements. L ¹ and L ² each independently represents a ligand. L ¹ and L ² may be linked to form a saturated or unsaturated ring.

The chalcogen element refers to S, Se, or Te among VI-B group elements (also referred to as group 16 elements). The chalcogen elements X ^{1 to} X ³ and the organic groups R ^{1 to} R ³ constitute an organic chalcogen compound represented by R ¹ X ¹ , R ² X ² and R ³ X ³ . The organic chalcogen compound is an organic compound to which a chalcogen element is bonded, and examples thereof include thiol, sulfide, disulfide, selenol, selenide, diselenide, tellurol, telluride, and ditelluride.

Further, organic groups represented as R ¹ to R ^3, from the viewpoint of easy synthesis, may be employed having a carbon number of 1 to 8.

The ligands represented as L ¹ and L ² are compounds that function as Lewis bases. Examples of such a ligand include a heterocyclic compound, a phosphine compound, and an amine compound.

  The first complex compound is used as a raw material for producing the semiconductor layer. As described later, the first complex compound can be used together with a II-B group compound (also referred to as a group 12 element) to produce a semiconductor layer containing a I-II-IV-VI group compound by a simple method. it can. In other words, since the IB group element, the IV-B group element, and the VI-B group element (chalcogen element) are close to each other in one complex molecule, the reactivity between these elements is high. As a result, the semiconductor layer is favorably generated.

(2. Structure of raw material for semiconductor layer formation)
The semiconductor layer forming raw material contains the first complex compound and the II-B group compound. The II-B group compound is a compound containing Zn among the II-B group elements, and various compounds such as an organic complex of the II-B group element can be used.

  The raw material for forming a semiconductor layer may contain a solvent in addition to the first complex compound and the II-B group compound in order to facilitate the formation of a film as a precursor of the semiconductor layer, and other additives. May be included.

  As the solvent used for the semiconductor layer forming raw material, a solvent capable of dissolving the first complex compound is used, and examples thereof include toluene, pyridine, xylene, acetone and the like. As described above, the semiconductor layer forming raw material is not a special solvent such as hydrazine as the solvent, and a general-purpose organic solvent can be adopted, so that no special equipment for treating the solvent is required in the manufacturing process of the semiconductor layer. The manufacturing process can be simplified.

  By heating the film of the raw material for forming a semiconductor layer as described above, a group I-B element, a group IV-B element and a group VI-B element (chalcogen element) and a group II-B in the first complex compound The II-B group element in a compound reacts satisfactorily, and a semiconductor layer containing an I-II-IV-VI group compound is formed satisfactorily.

  Further, from the viewpoint of high reactivity with the first complex compound and better formation of the I-II-IV-VI group compound, the II-B group compound has a structural formula in the raw material for forming the semiconductor layer. It may be contained as a second complex compound represented by (2).

In Structural Formula (2), M ³ represents Zn among the II-B group elements. R ^{4 to} R ⁷ each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted heterocyclic group . Also ^represents S or Se to X 4 to X ⁷ are each independently. Y ^{n +} represents an n-valent cation when n is a natural number.

The chalcogen elements X ^{4 to} X ⁷ and the organic groups R ^{4 to} R ⁷ constitute an organic chalcogen compound represented by R ⁴ X ⁴ , R ⁵ X ⁵ , R ⁶ X ⁶ and R ⁷ X ⁷ . . As the organic chalcogen compounds R ⁴ X ^{4 to} R ⁷ X ⁷ , various compounds as mentioned in the organic chalcogen compounds R ¹ X ^{1 to} R ³ X ³ can be used.

The organic group represented as R ⁴ to R ⁷ are, from the standpoint of ease synthesis, may be employed having a carbon number of 1 to 8.

  In such a second complex compound, the II-B group element and the VI-B group element (chalcogen element) are close to each other in one complex molecule, and bind to the first complex compound with high affinity. Therefore, not only the reactivity of the II-B group element and the VI-B group element (chalcogen element) in the second complex compound is high, but also the IB group element between the first complex compound and the second complex compound. , II-B group element, IV-B group element and VI-B group element (chalcogen element) are highly reactive. As a result, the I-II-IV-VI group compound is likely to be formed better.

  Further, from the viewpoint of easily controlling the molar ratio of the group I-B element, the group II-B element, the group IV-B element, and the group VI-B element (chalcogen element), the raw material for forming the semiconductor layer May further contain a third complex compound represented by the structural formula (3) in addition to the first complex compound and the II-B group compound.

In Structural Formula (3), M ⁴ and M ⁵ each represent Cu . R ⁸ and R ⁹ each independently represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted heterocyclic group . Also represents S or Se ^{X 8} and ^{X 9} each independently. L ^{3 to} L ⁶ each independently represent a ligand. Two or more of L ^{3 to} L ⁶ may be linked to form a saturated or unsaturated ring.

Incidentally, a chalcogen element ^X 8 to X ⁹ and an organic group ^R 8 to R ^{9 constitute} an organic chalcogen compound represented by R 8 ^{X 8} and ^R 9 ^{X 9.} As the organic chalcogen compounds R ⁸ X ⁸ and R ⁹ X ⁹ , various compounds as exemplified in the organic chalcogen compounds R ¹ X ^{1 to} R ³ X ³ can be used. Moreover, the ligand represented as L < ³ > -L < ⁶ > is a compound which functions as a Lewis base. As such a ligand, various compounds as exemplified in the ligands L ¹ and L ² can be used.

The organic group represented as R ⁸ to R ^9, from the viewpoint of easy synthesis, may be employed having a carbon number of 1 to 8.

  In such a third complex compound, the IB group element and the VI-B group element (chalcogen element) are close to each other in one complex molecule, and bind to the first complex compound with high affinity. Therefore, not only the reactivity of the IB group element and the VI-B group element (chalcogen element) in the third complex compound is high, but also the IB group between the first complex compound and the second complex compound. The reactivity of the element, II-B group element, IV-B group element and VI-B group element (chalcogen element) is increased. As a result, the I-II-IV-VI group compound can be formed satisfactorily and the composition adjustment is facilitated by adding the IB group element in the state of the third complex compound.

  In particular, when the semiconductor layer forming raw material includes the first complex compound, the second complex compound, and the third complex compound, a group IB element, a group II-B element, a group IV-B element, The molar ratio with the VI-B group element (chalcogen element) can be arbitrarily controlled, and a semiconductor layer having a desired composition can be produced favorably. Further, such a semiconductor layer forming raw material is in a state in which the first complex compound, the second complex compound, and the third complex compound are bonded with high affinity to each other in the semiconductor layer forming raw material. Therefore, when forming a film using the semiconductor layer forming raw material, it is possible to form a film in which the respective raw material elements are uniformly dispersed and close to each other without phase separation. As a result, when this film is heated, the raw material elements react well with each other, and the I-II-IV-VI group compound semiconductor layer can be formed satisfactorily.

  Moreover, the 4th complex compound represented by Structural formula (4) may be used as another example of the said II-B group compound.

In Structural Formula (4), M ⁶ and M ⁸ each represent Cu . M ⁷ represents Zn . R ^{10 to} R ¹³ each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted heterocyclic group . Also represents S or Se to X ¹⁰ to X ¹³ each independently. L < ⁷ > -L < ¹⁰ > represents a ligand each independently. L ^{7 to} L ¹⁰ may be linked to form a saturated or unsaturated ring.

Note that the chalcogen element ^X 10 ^{to X 13} and an organic group ^R 10 ^{to R 13,} constitute the organic chalcogen compound represented by ^{R 10 X 10, R 11 X} 11, R 12 X 12 and ^R 13 ^{X 13} . As the organic chalcogen compounds R ¹⁰ X ^{10 to} R ¹³ X ¹³ , various compounds such as those mentioned for the organic chalcogen compounds R ¹ X ^{1 to} R ³ X ³ can be used.

The organic group represented as R ¹⁰ to R ^13, from the viewpoint of easy synthesis, may be employed having a carbon number of 1 to 8.

^Moreover, ligands represented as L 7 ^{~L 10} is a compound which functions as a Lewis base. As such a ligand, various compounds as exemplified in the ligands L ¹ and L ² can be used.

  In such a fourth complex compound, a group I-B element, a group II-B element, and a group VI-B element (chalcogen element) are close to each other in one complex molecule, and the first complex compound and each other Bind with high affinity. Therefore, not only the reactivity of the IB group element, the II-B group element, and the VI-B group element (chalcogen element) in the fourth complex compound is high, but also between the first complex compound and the fourth complex compound. The reactivity of the IB group element, II-B group element, IV-B group element, and VI-B group element (chalcogen element) is increased. As a result, the I-II-IV-VI group compound is likely to be formed better.

  The semiconductor layer forming raw material may further contain at least one of the second complex compound and the third complex compound in addition to the first complex compound and the fourth complex compound. Thereby, the molar ratio of the IB group element, the II-B group element, the IV-B group element, and the VI-B group element (chalcogen element) can be easily controlled.

  The production steps of the first complex compound, the second complex compound, the third complex compound, and the fourth complex compound as described above will be described below.

(3. Preparation method of each complex compound)
<< 3-1. Method for producing first complex compound >>
The first complex compound can be prepared as follows. First, complex A and complex B are prepared. Then, using this complex A and complex B, a first complex compound is prepared.

<Preparation of complex A>
Complex A is a Lewis basic ligand having a higher coordination power than that of a metal complex in which an arbitrary ligand (eg acetonitrile) is coordinated to a group IB element. Replaced with a ligand. For example, when the group I-B element is M ^I , the arbitrary ligand is Q, the arbitrary anion is Z, and the Lewis basic ligand is L, the complex A is [L ₂ M ^I Q ₂ ] ⁺ Z ⁻ .

  As such a Lewis base, a heterocyclic compound, a phosphine compound, and an amine compound can be used.

  Examples of the heterocyclic compound include pyridine, quinoline, pyrazole, imidazole, oxazole, thiazole, benzimidazole, benzoxazole, benzothiazole, triazine, pyrimidine, pyrazine, piperidine, piperazine, morpholine which may have a substituent. Thiophene, furan, triazole, triazine, acridine and the like. From the viewpoint of increasing the reactivity with the complex B, pyridine, quinoline, imidazole, benzimidazole, or triazine may be used as the heterocyclic compound.

  Examples of the phosphine compound include triphenylphosphine, propyldiphenylphosphine, tert-butyldiphenylphosphine, 1-butyldiphenylphosphine, 1-hexyldiphenylphosphine, cyclohexyldiphenylphosphine, dicyclohexylphenylphosphine, tricyclohexylphosphine, trimethylphosphine, tri ( 2-furyl) phosphine, tri (3-furyl) phosphine, tri (2-pyridyl) phosphine, tri (3-pyridyl) phosphine, tri (4-pyridyl) phosphine, 2-furyldiphenylphosphine, 3-furyldiphenylphosphine, Examples include 2-pyridyldiphenylphosphine, 3-pyridyldiphenylphosphine, 4-pyridyldiphenylphosphine, and the like. From the viewpoint of increasing the reactivity with the complex B, as the phosphine compound, triphenylphosphine, tricyclohexylphosphine, trimethylphosphine, tri (2-furyl) phosphine, tri (3-furyl) phosphine, tri (2-pyridyl) phosphine , Tri (3-pyridyl) phosphine, tri (4-pyridyl) phosphine, 2-furyldiphenylphosphine, 3-furyldiphenylphosphine, 2-pyridyldiphenylphosphine, 3-pyridyldiphenylphosphine, 4-pyridyldiphenylphosphine Good. In particular, triphenylphosphine has good handleability. In addition, the phenyl group, cyclohexyl group, furyl group, and pyridyl group of the phosphine compound illustrated here may have a substituent.

  Examples of the amine compound include triphenylamine, diphenylamine, propyldiphenylamine, tert-butyldiphenylamine, n-butyldiphenylamine, n-hexyldiphenylamine, cyclohexyldiphenylamine, dicyclohexylphenylamine, tricyclohexylamine, trimethylamine, and dimethylamine. . From the viewpoint of increasing the reactivity with the complex B, triphenylamine, diphenylamine, tricyclohexylamine, trimethylamine, or dimethylamine may be used as the amine compound. In addition, the phenyl group and cyclohexyl group of the amine compound illustrated here may have a substituent.

Complex A can be prepared, for example, as shown in Reaction Formula (1). When the group I-B element is M ^I , an arbitrary ligand is Q, and Z is an arbitrary anion, the group I-B complex [M ^I Q ₄ ] ⁺ Z ⁻ is converted into, for example, acetonitrile, acetone Dissolve in a solvent such as methanol, ethanol, isopropanol. Then, by dissolving the Lewis base L in this solution, a part of the ligand of the group IB complex is substituted with the Lewis base, and [L ₂ M ^I Q ₂ ] ⁺ Z ⁻ is generated as the complex A. .

Specific examples of preparation of Complex A are shown below. A metal complex such as Cu (CH ₃ CN) ₄ .PF ₆ is dissolved in a solvent such as acetonitrile as a group IB complex. Then, P (C ₆ H ₅ ) ₃ is dissolved as a Lewis base L in this solution, whereby complex A is generated as {P (C ₆ H ₅ ) ₃ } ₂ Cu (CH ₃ CN) ₂ .PF ₆ . .

<Preparation of complex B>
Complex B is a complex compound in which an organic chalcogen compound is coordinated to an IV-B group element. Examples of such an organic chalcogen compound include thiol, selenol, tellurol, and the like in which a chalcogen element is bonded to an organic compound such as acrylic, aryl, alkyl, vinyl, perfluoro, and carbamate. Complex B, for example, a Group IV-B element and M ^IV, a salt of an organic chalcogen compound Y (RX) (R is an organic compound, X is chalcogen element, Y is any cation) The complex B can be represented as Y [M ^IV (XR) ₃ ].

Complex B can be prepared, for example, as shown in Reaction Formula (2). Group IV-B element M salt of ^IV M ^IV Z ₂ (e.g., including a metal oxide or SnCl _2, etc. of metal chlorides SnO etc.), and salts of organic chalcogen compound YXR (e.g., Na _(SC 6 _{H 5} ) And the like) in a solvent such as methanol, ethanol, propanol, etc., to produce Y [M ^IV (XR) ₃ ] as complex B.

Specific examples of preparation of Complex B are shown below. By dissolving SnCl ₂ as a salt of the IV-B group element M ^IV and Na (SC ₆ H ₅ ) as a salt of the organic chalcogen compound in a solvent such as methanol, they react to form Na ⁺ [ Sn (SC ₆ H ₅ ) ₃ ] ⁻ is produced.

<Preparation of first complex compound using complex A and complex B>
By mixing the solution of the complex A and the solution of the complex B produced as described above, the complex A and the complex B react to contain a group IB element, a group IV-B element, and a chalcogen element. This produces a precipitate containing the first complex compound represented by the structural formula (5). The temperature at which the complex A and the complex B are reacted is, for example, 0 to 30 ° C., and the reaction time is, for example, 1 to 5 hours. The precipitate containing the first complex compound may be washed using a technique such as centrifugation or filtration in order to remove impurities such as Na and Cl. In addition, Ph shown by Structural formula (5) etc. is a phenyl group.

<< 3-2. Method for producing second complex compound >>
The second complex compound can be prepared, for example, as shown below. First, an organic chalcogen compound and a Lewis base are dissolved in a solvent. And a 2nd complex compound produces | generates by melt | dissolving a II-B group element in this solution directly in the state of a simple substance or an alloy. The produced second complex compound can be isolated as a precipitate by dropping a nonpolar organic solvent such as petroleum ether, hexane, or toluene into the above solution.

  As the organic chalcogen compound used for the second complex compound, the compounds shown for the organic chalcogen compound used for the first complex compound can be used. Note that the organic chalcogen compound used in the first complex compound and the organic chalcogen compound used in the second complex compound may be the same or different.

  The Lewis base used for the production of the second complex compound functions as a cation of the second complex compound. As such a Lewis base, ammonia, an amine compound, or the like can be used.

  The mixing ratio of the organic chalcogen compound and the Lewis base in producing the second complex compound may be, for example, 0.01 to 2.5 times the Lewis base in terms of molar ratio.

  Specific examples of the production of the second complex compound are shown below. First, thiophenol as an organic chalcogen compound and aniline as a Lewis base are mixed. And after dissolving metal zinc as a II-B group element in this mixed solution, the 2nd complex compound represented by Structural formula (6) is precipitated by adding nonpolar organic solvents, such as hexane. Arises as

<< 3-3. Method for producing third complex compound >>
The third complex compound can be produced using the complex A produced by the same method as the synthesis of the first complex compound and the salt of the organic chalcogen compound.

  As the organic chalcogen compound used for the third complex compound, a compound shown by the organic chalcogen compound used for the first complex compound can be used. Note that the organic chalcogen compound used in the first complex compound and the organic chalcogen compound used in the third complex compound may be the same or different.

Specific examples of the production of the third complex compound are shown below. {P (C ₆ H ₅ ) ₃ } ₂ Cu (CH ₃ CN) ₂ .PF ₆ as complex A used in the preparation of the first complex compound, and Na (SC ₆ H ₅ ) as a salt of the organic chalcogen compound Are mixed in an equimolar amount of a solvent such as methanol, ethanol, propanol or the like to form a third complex compound represented by the structural formula (7).

<< 3-4. Method for preparing fourth complex compound >>
The fourth complex compound can be prepared using the complex A and the second complex compound. By mixing the complex A and the second complex compound in a solvent, the complex A and the second complex compound react to form a fourth complex compound.

Specific examples of the production of the fourth complex compound are shown below. The complex A includes {P (C ₆ H ₅ ) ₃ } ₂ Cu (CH ₃ CN) ₂ .PF ₆ and the second complex compound represented by the structural formula (6), and the second complex compound is complex A. The fourth complex compound represented by the structural formula (8) is produced by mixing in a solvent such as methanol, ethanol, propanol or the like so as to have a ½ molar amount of

(4. Manufacturing method of semiconductor layer)
A method for manufacturing a semiconductor layer using the semiconductor layer forming raw material as described above will be described below. First, a film as a precursor of a semiconductor layer is formed on the surface of a semiconductor layer formation target (hereinafter, the semiconductor layer formation target is simply referred to as a target) using the semiconductor layer forming raw material. The film can be formed, for example, by applying a semiconductor layer forming raw material liquefied using a solvent or the like to the surface of an object using a spin coater, screen printing, dipping, spraying, a die coater, or the like and drying. This drying may be performed in a reducing atmosphere. The temperature at the time of drying is 50-300 degreeC, for example.

  And the said membrane | film | coat can be heat-processed and the semiconductor layer of thickness 1-2.5 micrometers can be produced. The heat treatment may be performed in a non-oxidizing gas atmosphere in order to prevent oxidation and form a good semiconductor layer. Examples of the non-oxidizing gas atmosphere in the heat treatment include a nitrogen atmosphere, a forming gas atmosphere, and a hydrogen atmosphere. The heat treatment temperature is, for example, 400 ° C to 600 ° C.

  By the above semiconductor layer manufacturing method, a semiconductor layer containing an I-II-IV-VI group compound can be satisfactorily manufactured. That is, the film produced using the semiconductor layer forming raw material is formed in the first complex compound in which the IB group element, the IV-B group element, and the VI-B group element (chalcogen element) are one molecule. Because they are close to each other, they are more reactive. Therefore, the I-II-IV-VI group compound is formed satisfactorily.

  In addition, although the said film | membrane can react using the VI-B group element (chalcogen element) contained in the 1st complex compound as a raw material, and can form the semiconductor layer containing a chalcogen element, separately to the raw material for semiconductor layer formation, A chalcogen element may be included as a chalcogen compound. Further, a chalcogen element may be included in the atmosphere during the heat treatment of the film. By such a method, a chalcogen element that tends to be deficient due to evaporation or the like can be sufficiently supplied, and a semiconductor layer having a desired I-II-IV-VI group compound can be formed.

(5. Configuration of photoelectric conversion device)
FIG. 1 is a perspective view showing an example of an embodiment of a photoelectric conversion device manufactured using a method for manufacturing a semiconductor layer according to an embodiment of the present invention and a method for manufacturing a photoelectric conversion device according to an embodiment of the present invention. FIG. 2 is a sectional view thereof. The photoelectric conversion device 11 includes a substrate 1, a first electrode layer 2, a first semiconductor layer 3, a second semiconductor layer 4, and a second electrode layer 5. In the present embodiment, an example in which the first semiconductor layer 3 is a light absorption layer and the second semiconductor layer 4 is a buffer layer bonded to the first semiconductor layer 3 is not limited to this. The second semiconductor layer 4 may be a light absorption layer.

  1 and 2, the photoelectric conversion device 11 is formed by arranging a plurality of photoelectric conversion cells 10 side by side. The photoelectric conversion cell 10 includes a third electrode layer 6 provided on the substrate 1 side of the first semiconductor layer 3 so as to be separated from the first electrode layer 2. The second electrode layer 5 and the third electrode layer 6 are electrically connected by the connection conductor 7 provided in the first semiconductor layer 3. 1 and 2, the third electrode layer 6 is obtained by extending the first electrode layer 2 of the adjacent photoelectric conversion cell 10. With this configuration, adjacent photoelectric conversion cells 10 are connected in series. In one photoelectric conversion cell 10, the connection conductor 7 is provided so as to penetrate the first semiconductor layer 3 and the second semiconductor layer 4, and the first electrode layer 2 and the second electrode layer are provided. The first semiconductor layer 3 and the second semiconductor layer 4 sandwiched between 5 and 5 perform photoelectric conversion.

  The substrate 1 is for supporting the photoelectric conversion cell 10. Examples of the material used for the substrate 1 include glass, ceramics, resin, and metal.

  The first electrode layer 2 and the third electrode layer 6 are made of a conductor such as Mo, Al, Ti, or Au, and are formed on the substrate 1 by a sputtering method or a vapor deposition method.

The first semiconductor layer 3 is a semiconductor layer mainly containing an I-II-IV-VI group compound. An I-II-IV-VI group compound is a compound semiconductor of an IB group element, an II-B group element, an IV-B group element, and a VI-B group element. Examples of the I-II-IV-VI group compound include Cu ₂ ZnSnS ₄ (also referred to as CZTS) and Cu ₂ ZnSnS _4-x Se _x (also referred to as CZTSSe. Note that x is a number greater than 0 and smaller than 4. And Cu ₂ ZnSnSe ₄ (also referred to as CZTSe). Since such an I-II-IV-VI group compound has a large light absorption coefficient, an effective electromotive force can be obtained even when used as a thin layer of 10 μm or less.

  The first semiconductor layer 3 can be produced using the semiconductor layer manufacturing method according to the embodiment of the present invention described above. That is, a substrate 1 having a first electrode layer 2 provided on the surface is prepared, and a film is formed on the first electrode layer 2 using a semiconductor layer forming raw material. And the 1st semiconductor layer 3 containing an I-II-IV-VI group compound can be formed by heat-processing this membrane | film | coat.

  In the photoelectric conversion cell 10, a second semiconductor layer 4 having a conductivity type different from that of the first semiconductor layer 3 is formed on the first semiconductor layer 3 with a thickness of, for example, 10 to 200 nm. The first semiconductor layer 3 and the second semiconductor layer 4 have different conductivity types, one being n-type and the other being p-type, and these are pn-junctioned. The first semiconductor layer 3 may be p-type and the second semiconductor layer 4 may be n-type, or the reverse relationship may be used. Note that the pn junction by the first semiconductor layer 3 and the second semiconductor layer 4 is not limited to the one in which the first semiconductor layer 3 and the second semiconductor layer 4 are directly joined. For example, another semiconductor layer having the same conductivity type as that of the first semiconductor layer 3 or another semiconductor layer having the same conductivity type as that of the second semiconductor layer 4 may be further provided therebetween. Further, a pin junction having an i-type semiconductor layer may be provided between the first semiconductor layer 3 and the second semiconductor layer 4.

The first semiconductor layer 3 and the second semiconductor layer 4 may be homojunctions or heterojunctions. In the case of a heterojunction, the second semiconductor layer 4 includes CdS, ZnS, ZnO, In ₂ Se ₃ , In (OH, S), (Zn, In) (Se, OH), and (Zn, Mg). O etc. are mentioned, For example, it forms with a thickness of 10-200 nm by the chemical bath deposition (CBD) method etc. In (OH, S) refers to a compound mainly composed of In, OH, and S. (Zn, In) (Se, OH) refers to a compound mainly composed of Zn, In, Se, and OH. (Zn, Mg) O refers to a compound mainly composed of Zn, Mg and O.

  The second electrode layer 5 is a 0.05 to 3 μm transparent conductive film such as ITO or ZnO. The second electrode layer 5 is formed by sputtering, vapor deposition, chemical vapor deposition (CVD), or the like. The second electrode layer 5 is a layer having a resistivity lower than that of the second semiconductor layer 4, and is for taking out charges generated in the first semiconductor layer 3. From the viewpoint of taking out charges well, the resistivity of the second electrode layer 5 may be less than 1 Ω · cm and the sheet resistance may be 50 Ω / □ or less.

  The photoelectric conversion device 11 is formed by arranging a plurality of photoelectric conversion cells 10 and electrically connecting them. In order to easily connect adjacent photoelectric conversion cells 10 in series, as shown in FIGS. 1 and 2, the photoelectric conversion cell 10 is connected to the first electrode layer 2 on the substrate 1 side of the first semiconductor layer 3. A third electrode layer 6 is provided so as to be spaced apart. The second electrode layer 5 and the third electrode layer 6 are electrically connected by the connection conductor 7 provided in the first semiconductor layer 3.

  In FIG. 1, the connection conductor 7 is formed by filling a conductor such as a conductive paste in a groove that penetrates the first semiconductor layer 3, the second semiconductor layer 4, and the second electrode layer 5. . The connection conductor 7 is not limited to this, and may be formed by extending the second electrode layer 5.

  Moreover, the collector electrode 8 may be provided on the 2nd electrode layer 5 like FIG. 1, FIG. The collecting electrode 8 is for reducing the electric resistance of the second electrode layer 5. By providing the current collecting electrode 8 on the second electrode layer 5, the thickness of the second electrode layer 5 is reduced to increase the light transmittance, and the current generated in the first semiconductor layer 3 is efficiently generated. It is taken out. As a result, the power generation efficiency of the photoelectric conversion device 11 is increased.

  For example, as shown in FIG. 1, the collector electrode 8 is formed in a linear shape from one end of the photoelectric conversion cell 10 to the connection conductor 7. As a result, the electric charge generated by the photoelectric conversion of the first semiconductor layer 3 is collected by the current collecting electrode 8 through the second electrode layer 5, and is excellent in the adjacent photoelectric conversion cell 10 through the connection conductor 7. Communicated.

  The width of the current collecting electrode 8 can be set to 50 to 400 μm from the viewpoint of reducing light shielding to the first semiconductor layer 3 and having good conductivity. The current collecting electrode 8 may have a plurality of branched portions.

  The collector electrode 8 is formed, for example, by printing a metal paste in which a metal powder such as Ag is dispersed in a resin binder or the like in a pattern and curing it.

  It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

<Synthesis of first complex compound>
As the first complex compound, (Ph ₃ P) ₂ Cu (SPh) ₂ Sn (SPh) represented by the structural formula (5) was synthesized.

  All of the following operations were performed in a glove box sufficiently substituted with dry nitrogen. First, a 300 ml Meyer flask was prepared, and 10 mmol of tetrakis acetonitrile copper (I) tetrafluoroborate as a metal complex of a group IB element and 30 mmol of triphenylphosphine as a Lewis base were weighed. Further, 100 ml of dehydrated methanol was added, and the mixture was stirred with a magnetic stirrer at room temperature for 3 hours (this solution is referred to as reaction solution 1).

  A 1000 ml Meyer flask was prepared, 30 mmol of sodium methoxide was weighed, 500 ml of dehydrated methanol was added, and the mixture was stirred with a magnetic stirrer until completely dissolved. To this solution, 30 mmol of phenylthiol was added and stirred for 15 minutes, then 10 mmol of tin (II) chloride (anhydrous) was added, and the mixture was further stirred for 1 hour (this solution is referred to as reaction solution 2).

  The reaction solution 1 was added dropwise to the Meyer flask containing the reaction solution 2 and further stirred for 2 hours. The produced yellow precipitate was collected by filtration, washed with dehydrated methanol, and then dried under reduced pressure to obtain the desired product. The yield was 90%.

<Synthesis of second complex compound>
(NH ₄ ) ₂ Zn (SPh) ₄ shown in the structural formula (6) was synthesized as the second complex compound.

  All of the following operations were performed in a glove box sufficiently substituted with dry nitrogen. A 30 ml Meyer flask equipped with a reflux condenser was prepared, and a mixed solution was prepared by mixing 50 mmol of aniline as a Lewis base and 60 mmol of phenylthiol as an organic chalcogen compound, and then at room temperature for 1 hour with a magnetic stirrer. Stir. 10 mmol of zinc was added to the mixture and stirred at 70 ° C. for 12 hours. After allowing to cool to room temperature, the reaction solution was slowly added dropwise to a 300 ml Meyer flask containing 150 ml of n-hexane. The obtained precipitate was collected by filtration, washed with n-hexane, and then dried under reduced pressure to obtain the desired product. The yield was 70%.

<Synthesis of the third complex compound>
(Ph ₃ P) ₂ Cu (SPh) ₂ Cu (PPh ₃ ) shown in the structural formula (7) was synthesized as the first complex compound.

  All of the following operations were performed in a glove box sufficiently substituted with dry nitrogen. First, a 300 ml Meyer flask was prepared, and 10 mmol of tetrakis acetonitrile copper (I) tetrafluoroborate as a metal complex of a group IB element and 30 mmol of triphenylphosphine as a Lewis base were weighed. Further, 100 ml of dehydrated methanol was added, and the mixture was stirred with a magnetic stirrer at room temperature for 3 hours (this solution is referred to as reaction solution 3).

  A 300 ml Meyer flask was prepared, 10 mmol of sodium methoxide was weighed, 200 ml of dehydrated methanol was added, and the mixture was stirred with a magnetic stirrer until completely dissolved. To this solution, 10 mmol of phenylthiol was added and stirred for 1 hour (this solution is referred to as reaction solution 4).

  The reaction solution 3 was dropped into a Meyer flask containing the reaction solution 4, and the mixture was further stirred for 2 hours. The produced yellow precipitate was collected by filtration, washed with dehydrated methanol, and then dried under reduced pressure to obtain the desired product. The yield was 95%.

<Preparation of raw material for semiconductor layer formation>
All of the following operations were performed in a glove box sufficiently substituted with dry nitrogen. (Ph ₃ P) ₂ Cu (SPh) ₂ Sn (SPh) 7.46 g, (NH ₄ ) ₂ Zn (SPh) ₄ 1.05 g, and (Ph ₃ P) ₂ Cu (SPh) ₂ Cu (PPh ₃ ) was weighed 2.75 g each and dissolved in 16.9 g of commercially available dehydrated pyridine (water content <50 ppm) to prepare a liquid semiconductor layer forming raw material.

<Production of photoelectric conversion device>
A coating film was formed on the first electrode layer 2 made of Mo of the soda lime glass substrate 1 by using the above-mentioned raw material for forming a semiconductor layer by a doctor blade method. The coating film was formed by applying a semiconductor layer forming raw material to the first electrode layer 2 using nitrogen gas as a carrier gas in a glove box. After coating, the sample was dried at 110 ° C. on a hot plate for 5 minutes to form a film.

  After film formation, heat treatment was performed in a hydrogen gas atmosphere. The heat treatment is performed by rapidly raising the temperature to 525 ° C. in 5 minutes and holding it at 525 ° C. for 1 hour, and then naturally cooling the first semiconductor layer 3 made of a compound semiconductor thin film having a thickness of 1.5 μm. Produced.

From the X-ray diffraction result of the first semiconductor layer 3, it was found that the obtained first semiconductor layer 3 was Cu ₂ ZnSnS ₂ .

  Thereafter, cadmium acetate and thiourea were dissolved in aqueous ammonia, and the sample was immersed in the solution to form a second semiconductor layer 4 made of CdS having a thickness of 0.05 μm on the first semiconductor layer 3. Further, an Al-doped zinc oxide film (second electrode layer 5) was formed on the second semiconductor layer 4 by a sputtering method. Finally, an aluminum electrode (extraction electrode) was formed by vapor deposition to produce a photoelectric conversion device 11.

<Evaluation of photoelectric conversion device>
The photoelectric conversion efficiency of this photoelectric conversion device 11 was measured using a steady light solar simulator. Here, the photoelectric conversion efficiency was measured under conditions where the light irradiation intensity on the light receiving surface of the photoelectric conversion device 11 was 100 mW / cm ² and the air mass (AM) was 1.5. The photoelectric conversion efficiency indicates the rate at which sunlight energy is converted into electric energy in the photoelectric conversion device 11. Here, the value of the electric energy output from the photoelectric conversion device 11 is incident on the photoelectric conversion device 11. Divided by the value of the energy of solar light to be multiplied by 100.

  As a result, the photoelectric conversion efficiency of the photoelectric conversion device manufactured as described above was 7.6%, and it was confirmed that the photoelectric conversion device had good characteristics.

  As described above, according to the present invention, it was found that a semiconductor layer containing a I-II-IV-VI group compound can be produced by a simple method without using a vacuum process or toxic hydrazine.

1: Substrate 2: First electrode layer 3: First semiconductor layer (semiconductor layer containing a I-II-IV-VI group compound)
4: Second semiconductor layer 5: Second electrode layer 6: Third electrode layer 7: Connection conductor 8: Current collecting electrode 10: Photoelectric conversion cell 11: Photoelectric conversion device

Claims (7)

A complex compound represented by Structural Formula (1).
(In the formula, M ¹ represents Cu . M ² represents Sn . R ^{1 to} R ³ each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted group. Represents a cycloalkyl group or a substituted or unsubstituted heterocyclic group, X ^{1 to} X ³ each independently represents S or Se, and L ¹ and L ² each independently represent a ligand, where L 1 ¹ and L ² may combine to form a saturated or unsaturated ring.) The raw material for semiconductor layer formation containing the complex compound of Claim 1, and the II-B group compound whose II-B group element is Zn . The raw material for semiconductor layer formation of Claim 2 which contains the said II-B group compound as a 2nd complex compound represented by Structural formula (2).
(Wherein M ³ represents Zn . R ^{4 to} R ⁷ are each independently a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted cycloalkyl group, Represents an unsubstituted heterocyclic group, X ^{4 to} X ⁷ each independently represent S or Se, and Y ^{n +} represents an n-valent cation when n is a natural number. The raw material for forming a semiconductor layer according to claim 2 or 3, further comprising a third complex compound represented by the structural formula (3).
(Wherein M ⁴ and M ⁵ each represent Cu . R ⁸ and R ⁹ each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group, Or a substituted or unsubstituted heterocyclic group, X ⁸ and X ⁹ each independently represent S or Se, and L ^{3 to} L ⁶ each independently represent a ligand, where L ^{3 to} L Two or more of ⁶ may be linked to form a saturated or unsaturated ring.) The raw material for semiconductor layer formation in any one of Claim 2 thru | or 4 which contains the said II-B group compound as a 4th complex compound represented by Structural formula (4).
(In the formula, M ⁶ and M ⁸ each represent Cu . M ⁷ represents Zn . R ^{10 to} R ¹³ each independently represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted group. Alternatively, it represents an unsubstituted cycloalkyl group or a substituted or unsubstituted heterocyclic group, X ^{10 to} X ¹³ each independently represents S or Se, and L ^{7 to} L ¹⁰ each independently represent a ligand. Here, L ^{7 to} L ¹⁰ may be linked to form a saturated or unsaturated ring. Forming a film using the semiconductor layer forming raw material according to any one of claims 2 to 5,
Heating the film to form a semiconductor layer containing a group I-II-IV-VI compound. Producing a first semiconductor layer by the method for producing a semiconductor layer according to claim 6;
And a step of producing a second semiconductor layer having a conductivity type different from that of the first semiconductor layer so as to be electrically connected to the first semiconductor layer. Production method.