JP2014127578A - Semiconductor film, method for manufacturing semiconductor film, solar cell, light emitting diode, thin film transistor and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor film capable of achieving high light current value and suppressing film peeling.SOLUTION: A semiconductor film has an aggregate of semiconductor quantum dots containing metal atom; and a ligand coordinated to the semiconductor quantum dot and selected from a group consisting of a tertiary amine having three or more, in total, of one kind or more functional group selected from SH, NHand OH, and its derivative.

Description

  The present invention relates to a semiconductor film, a semiconductor film manufacturing method, a solar cell, a light emitting diode, a thin film transistor, and an electronic device.

  In recent years, research on high-efficiency solar cells called third-generation solar cells has been actively conducted. Among them, a solar cell using colloidal quantum dots has been reported to have improved quantum efficiency due to, for example, a multi-exciton generation effect, and has attracted attention (for example, see Non-Patent Document 1). However, in a solar cell using colloidal quantum dots (also referred to as a quantum dot solar cell), the conversion efficiency is about 7% at the maximum, and further improvement in conversion efficiency is required.

In such a quantum dot solar cell, since a semiconductor film made of an assembly of quantum dots serves as a photoelectric conversion layer, research on the semiconductor film itself made of an assembly of quantum dots has been actively conducted.
For example, semiconductor nanoparticles using a relatively long ligand having 6 or more hydrocarbon groups are disclosed (for example, see Patent Document 1).
As a technique for improving the characteristics of a semiconductor film made up of an assembly of quantum dots, the ligand molecules bonded to the quantum dots (for example, about 2 nm to 10 nm) are replaced with shorter ligand molecules, and the It has been reported that conductivity is improved (for example, see Non-Patent Document 2). In Non-Patent Document 2, by replacing the oleic acid (molecular chain length of about 2 nm to 3 nm) around the PbSe quantum dots with ethanedithiol (molecular chain length of 1 nm or less), the quantum dots become close to each other and the electrical conductivity is increased. It has been reported to improve.

Japanese Patent No. 4425470

S. Geyer et al., "Charge transport in mixed CdSe and CdTe colloidal nanofilms", Physical Review B (2010). J. et al. M.M. By Luther et al. “Structural, Optical, and Electrical Properties of Self-Assembled Films of PbSe Nanocyclics Treated with 1, 2-Ethanidiol”, ACS Nano (2008)

  However, since the semiconductor film described in Patent Document 1 has a large ligand and insufficient proximity between the semiconductor quantum dots, the photoelectric conversion characteristics are not excellent. In addition, even when butylamine used in Non-Patent Document 1 or ethanedithiol used in Non-Patent Document 2 is used as a ligand, for example, according to Non-Patent Document 1, several hundreds at the maximum. Only a photocurrent value of about nA can be obtained. Further, when ethanedithiol is used as a ligand, the semiconductor film is likely to be peeled off.

An object of the present invention is to provide a semiconductor film in which a high photocurrent value is obtained and film peeling is suppressed, and a method for manufacturing the semiconductor film, and an object thereof is to solve the problem.
It is another object of the present invention to provide a solar cell, a light-emitting diode, a thin film transistor, and an electronic device in which high photocurrent values are obtained and film peeling is suppressed.

In order to achieve the above object, the following invention is provided.
<1> an assembly of semiconductor quantum dots containing metal atoms;
At least one ligand selected from the group consisting of tertiary amines coordinated to semiconductor quantum dots and having a total of three or more functional groups selected from SH, NH ₂ and OH, and derivatives thereof; ,
A semiconductor film.
<2> The semiconductor film according to <1>, wherein the ligand is represented by the following general formula (A).

(In formula (A), X ¹ , X ² and X ³ each independently represent SH, NH ₂ or OH, and p, q and r each independently represent an integer of 1 or more and 4 or less.)
<3> The semiconductor film according to <2>, further including a substituent having 10 or less atoms in at least one of (CH ₂ ) p, (CH ₂ ) q, and (CH ₂ ) r in the general formula (A). .
<4> The semiconductor film according to <3>, wherein the substituent has 7 or less atoms.
<5> The semiconductor film according to <2>, wherein (CH ₂ ) p, (CH ₂ ) q, and (CH ₂ ) r in the general formula (A) are all unsubstituted.
<6> The semiconductor film according to <1> to <5>, wherein the ligand is tris (2-aminoethyl) amine or a derivative thereof.
<7> The semiconductor film according to <2> to <6>, wherein the ligand is represented by the general formula (A) and is tripod-type coordinated to the metal atom in the semiconductor quantum dot.
<8> The semiconductor film according to any one of <1> to <7>, wherein the semiconductor quantum dots include at least one selected from PbS, PbSe, InN, InAs, InSb, and InP.
<9> The semiconductor film according to any one of <1> to <8>, wherein the semiconductor quantum dot has an average particle diameter of 2 nm to 15 nm.
<10> The semiconductor film according to <8> or <9>, wherein the semiconductor quantum dot contains PbS.
<11> A semiconductor quantum dot dispersion containing a semiconductor quantum dot containing a metal atom, a first ligand coordinated to the semiconductor quantum dot, and a first solvent is applied to the substrate. A semiconductor quantum dot assembly forming process for forming the assembly;
A second amine which is a tertiary amine having a molecular chain length shorter than that of the first ligand and having a total of three or more functional groups selected from SH, NH ₂ and OH, or a derivative thereof; A ligand solution containing a ligand and a second solvent is applied to an assembly of semiconductor quantum dots, and the first ligand coordinated to the semiconductor quantum dots is defined as the second ligand. A ligand exchange step to exchange with
The manufacturing method of the semiconductor film which has this.
<12> The method for producing a semiconductor film according to <11>, wherein the second ligand is represented by the following general formula (A).

(In formula (A), X ¹ , X ² and X ³ each independently represent SH, NH ₂ or OH, and p, q and r each independently represent an integer of 1 or more and 4 or less.)
<13> The semiconductor film according to <12>, further having a substituent having 10 or less atoms in at least one of (CH ₂ ) p, (CH ₂ ) q, and (CH ₂ ) r in the general formula (A). Manufacturing method.
<14> The method for producing a semiconductor film according to <13>, wherein the substituent has 7 or less atoms.
<15> The method for producing a semiconductor film according to <12>, wherein (CH ₂ ) p, (CH ₂ ) q, and (CH ₂ ) r in the general formula (A) are all unsubstituted.
<16> The method for producing a semiconductor film according to any one of <11> to <15>, wherein the second ligand is tris (2-aminoethyl) amine or a derivative thereof.
<17> The second ligand is represented by the general formula (A), and any one of <12> to <16> is a ligand that is tripodically coordinated to a metal atom in the semiconductor quantum dot. A method for producing a semiconductor film according to claim 1.
<18> The semiconductor film manufacturing method according to any one of <11> to <17>, wherein the semiconductor quantum dots include at least one selected from PbS, PbSe, InN, InAs, InSb, and InP.
<19> The method for producing a semiconductor film according to any one of <11> to <18>, wherein the semiconductor quantum dots have an average particle diameter of 2 nm to 15 nm.
<20> The method for producing a semiconductor film according to <18> or <19>, wherein the semiconductor quantum dots contain PbS.
<21> A solar cell comprising the semiconductor film according to any one of <1> to <10>.
<22> A light emitting diode comprising the semiconductor film according to any one of <1> to <10>.
<23> A thin film transistor comprising the semiconductor film according to any one of <1> to <10>.
<24> An electronic device comprising the semiconductor film according to any one of <1> to <10>.

ADVANTAGE OF THE INVENTION According to this invention, a high photocurrent value is obtained and the semiconductor film with which film | membrane peeling is suppressed and its manufacturing method are provided.
In addition, according to the present invention, there are provided a solar cell, a light emitting diode, a thin film transistor, and an electronic device that can obtain a high photocurrent value and suppress film peeling.

It is the schematic which shows an example of a structure of the pn junction type solar cell to which the semiconductor film of this invention is applied. It is the schematic which shows the comb-type electrode substrate used in the Example. It is the schematic which shows the method of irradiating a monochromatic light to the semiconductor film (device for evaluation) produced in the Example.

  Hereinafter, the present invention will be described in detail.

<Semiconductor film>
The semiconductor film of the present invention has an aggregate of semiconductor quantum dots containing metal atoms and a coordinate with the semiconductor quantum dots, and has a total of three or more functional groups selected from SH, NH ₂ and OH. And at least one ligand selected from the group consisting of a secondary amine and derivatives thereof (hereinafter sometimes referred to as “specific ligand”).
In the semiconductor film of the present invention, the coordination functional group SH, NH ₂ , or OH is coordinated with the metal atom of the quantum dot in a tripod shape (tridentate) or more, thereby dangling on the surface of the quantum dot. By strongly compensating for dangling bonds and increasing the degree of proximity between quantum dots, it is considered that film peeling is suppressed and a semiconductor film having high electrical conductivity is obtained.

  A semiconductor quantum dot is a semiconductor particle including a metal atom, and is a nano-sized particle having a particle size of several nanometers to several tens of nanometers.

Although the details of the method for producing a semiconductor film of the present invention will be described later, the semiconductor film of the present invention is, for example, an assembly of semiconductor quantum dots coordinated with a first ligand as a specific ligand. A second amine which is a tertiary amine having a molecular chain length shorter than that of the first ligand and having a total of three or more functional groups selected from SH, NH ₂ and OH, or a derivative thereof; It can be obtained by adding a ligand.
Hereinafter, details of each element constituting the semiconductor film of the present invention will be described.

[Specific ligand]
The specific ligand coordinated to the semiconductor quantum dot in the semiconductor film of the present invention is a group consisting of a tertiary amine having a total of three or more functional groups selected from SH, NH ₂ and OH, and derivatives thereof. It is a more selected ligand.
Moreover, it is preferable to have OH among SH, NH ₂ and OH contained in the specific ligand from the viewpoint of miscibility with an alcohol solvent and adhesion to a quartz substrate.
Specifically, the specific ligand is preferably a ligand represented by the following general formula (A).

In formula (A), X ¹ , X ² and X ³ each independently represent SH, NH ₂ or OH, and p, q and r each independently represent an integer of 1 or more and 4 or less.

When the specific ligand has the molecular structure as described above, the terminal SH, NH ₂ , and OH groups coordinate with a metal atom having a dangling bond on the surface of the quantum dot, thereby forming a tripodal multidentate configuration. The metal complex is easily formed. Therefore, the complex stability constant logβ between the ligand and the metal atom is likely to increase, the binding force between the metal atom and the ligand is increased, and the distance between the quantum dots is likely to be close, resulting in high electrical conductivity. It is thought that it becomes easy to obtain.

From the viewpoint of the proximity of the quantum dots, the number of carbon atoms in the alkylene group represented by (CH ₂ ) p, (CH ₂ ) q and (CH ₂ ) r is preferably 3 or less and more preferably 2 or less. In addition, at least one of (CH ₂ ) p, (CH ₂ ) q and (CH ₂ ) r may further have a substituent having 10 or less atoms, and when there is a substituent, The number of atoms is preferably 7 or less, and (CH ₂ ) p, (CH ₂ ) q and (CH ₂ ) r are more preferably all free of substituents.
When the complex stability constant log β of the specific ligand and the metal atom is 8 or more, the coordination power is particularly enhanced, and it can be expected that the electrical conductivity characteristics are improved by reducing the dangling bonds and the proximity of the quantum dots.

In the general formula (A), the substituent having 10 or less atoms that may be present in the alkylene group represented by (CH ₂ ) p, (CH ₂ ) q, and (CH ₂ ) r includes 1 to 1 carbon atoms. 3 alkyl groups [methyl group, ethyl group, propyl group, and isopropyl group], alkenyl groups having 2 to 3 carbon atoms [ethenyl group and propenyl group], alkynyl groups having 2 to 4 carbon atoms [ethynyl group, propynyl group, etc. ], A cyclopropyl group, an alkoxy group having 1 to 2 carbon atoms [methoxy group and ethoxy group], an acyl group having 2 to 3 carbon atoms [acetyl group and propionyl group], an alkoxycarbonyl group having 2 to 3 carbon atoms [methoxy group] Carbonyl group and ethoxycarbonyl group], C2-acyloxy group [acetyloxy group], C2-acylamino group [acetylamino group], C1-C3 hydroxy group. Alkyl group [hydroxymethyl group, hydroxyethyl group, hydroxypropyl group], an aldehyde group [-COH], hydroxy group [-OH], a carboxy group [-COOH], a sulfo group [-SO ₃ H], phospho group [- OPO _{(OH) 2],} amino [-NH _2], carbamoyl group [-CONH _2], a cyano group [-CN], an isocyanate group [-N = C = O], a thiol group [-SH], a nitro group [—NO ₂ ], nitroxy group [—ONO ₂ ], isothiocyanate group [—NCS], cyanate group [—OCN], thiocyanate group [—SCN], acetoxy group [OCOCH ₃ ], acetamide group [NHCOCH ₃ ], Formyl group [—CHO], formyloxy group [—OCHO], formamide group [—NHCHO], sulfamino group [—NH O ₃ H], sulfino group [-SO ₂ H] sulfamoyl group _[-SO 2 NH _2], a phosphono group _[-PO 3 _{H 2],} acetyl group [-COCH _3], a halogen atom [fluorine, chlorine , Bromine atoms, etc.], alkali metal atoms [lithium atoms, sodium atoms, potassium atoms, etc.] and the like.

  In the present invention, the specific ligand is preferably either tris (2-aminoethyl) amine or a tris (2-aminoethyl) amine derivative. In the case of any of the above ligands, a higher photocurrent can be obtained as compared with the case where a conventional ethanedithiol is used as a ligand.

[A collection of semiconductor quantum dots containing metal atoms]
The semiconductor film of the present invention has an aggregate of semiconductor quantum dots. Moreover, the semiconductor quantum dot has at least one kind of metal atom.
The aggregate of semiconductor quantum dots refers to a form in which a large number (for example, 100 or more per 1 μm ² square) of semiconductor quantum dots are arranged close to each other.
The “semiconductor” in the present invention means that the specific resistance value is 10 ⁻² Ωcm or more and 10 ⁸ Ωcm or less.

The semiconductor quantum dot is a semiconductor particle having a metal atom. In the present invention, the metal atom includes a semimetal atom typified by Si atom.
Examples of the semiconductor quantum dot material constituting the semiconductor quantum dot include a general semiconductor crystal [a) a group IV semiconductor, b) a compound semiconductor of group IV-IV, group III-V, or group II-VI, c) II. Compound semiconductor composed of a combination of three or more of Group, Group III, Group IV, Group V, and Group VI elements) (particles of 0.5 nm to less than 100 nm). Specific examples include semiconductor materials having a relatively narrow band gap such as PbS, PbSe, InN, InAs, Ge, InAs, InGaAs, CuInS, CuInSe, CuInGaSe, InSb, Si, and InP.
The semiconductor quantum dot should just contain at least 1 type of semiconductor quantum dot material.

  The semiconductor quantum dot material preferably has a bulk band gap of 1.5 eV or less. By using such a semiconductor material having a relatively narrow band gap, high conversion efficiency can be realized when the semiconductor film of the present invention is used, for example, in a photoelectric conversion layer of a solar cell.

  The semiconductor quantum dot may have a core-shell structure in which a semiconductor quantum dot material is a nucleus (core) and the semiconductor quantum dot material is covered with a coating compound. Examples of the coating compound include ZnS, ZnSe, ZnTe, ZnCdS, and the like.

  Among the above, the semiconductor quantum dot material is preferably PbS or PbSe from the viewpoint of easy synthesis of the semiconductor quantum dots. It is also desirable to use InN from the viewpoint that the environmental load is small.

Furthermore, when the semiconductor film of the present invention is applied to a solar cell application, the semiconductor quantum dot may have a narrower band gap in view of enhancement of photoelectric conversion efficiency due to a multi-exciton generation effect called a multi-exciton generation effect. preferable. Specifically, it is desirable that it is 1.0 eV or less.
From the viewpoint of narrowing the band gap and enhancing the multi-exciton generation effect, the semiconductor quantum dot material is preferably PbS, PbSe, or InSb.

The average particle size of the semiconductor quantum dots is desirably 2 nm to 15 nm. In addition, the average particle diameter of a semiconductor quantum dot means the average particle diameter of ten semiconductor quantum dots. A transmission electron microscope may be used to measure the particle size of the semiconductor quantum dots.
In general, semiconductor quantum dots include particles of various sizes from several nm to several tens of nm. In the semiconductor quantum dot, when the average particle diameter of the quantum dot is reduced to a size equal to or less than the Bohr radius of the underlying electron, a phenomenon occurs in which the band gap of the semiconductor quantum dot changes due to the quantum size effect. For example, it is said that II-VI semiconductors have a relatively large Bohr radius, and PbS has a diameter of about 18 nm. InP, which is a III-V group semiconductor, is said to have a Bohr radius of about 10 nm to 14 nm.
Therefore, for example, if the average particle size of the semiconductor quantum dots is 15 nm or less, the band gap can be controlled by the quantum size effect.

In particular, when the semiconductor film of the present invention is applied to a solar cell, it is important to adjust the band gap to an optimum value by the quantum size effect regardless of the semiconductor quantum dot material. However, since the band gap increases as the average particle size of the semiconductor quantum dots decreases, a larger change in the band gap can be expected if the average particle size of the semiconductor quantum dots is 10 nm or less. Even if the semiconductor quantum dot is a narrow gap semiconductor as a result, it is easy to adjust the band gap optimal for the spectrum of sunlight. Therefore, the size of the quantum dot is more preferably 10 nm or less. Further, when the average particle size of the semiconductor quantum dots is small and the quantum confinement is remarkable, there is an advantage that the enhancement of the multi-exciton generation effect can be expected.
On the other hand, the average particle diameter of the semiconductor quantum dots is preferably 2 nm or more. By setting the average particle diameter of the semiconductor quantum dots to 2 nm or more, the effect of quantum confinement does not become too strong, and the band gap can be easily set to the optimum value. Further, by setting the average particle diameter of the semiconductor quantum dots to 2 nm or more, it is possible to easily control the crystal growth of the semiconductor quantum dots in the synthesis of the semiconductor quantum dots.

  The thickness of the semiconductor film of the present invention is not particularly limited, but is preferably 10 nm or more and more preferably 50 nm or more from the viewpoint of obtaining high electrical conductivity. In addition, the thickness of the semiconductor film is preferably 300 nm or less from the viewpoint of excessive carrier concentration and ease of manufacture.

<Semiconductor film manufacturing method>
The method for producing the semiconductor film of the present invention is not particularly limited, but the semiconductor film of the present invention described below is from the viewpoint of reducing the interval between the semiconductor quantum dots and arranging the semiconductor quantum dots densely. It is preferable to manufacture by this manufacturing method.

In the method for producing a semiconductor film of the present invention, a semiconductor quantum dot dispersion containing a semiconductor quantum dot containing a metal atom, a first ligand coordinated to the semiconductor quantum dot, and a first solvent is formed on a substrate. A semiconductor quantum dot assembly forming step of forming an assembly of semiconductor quantum dots by applying, and one or more types selected from SH, NH ₂ and OH having a molecular chain length shorter than that of the first ligand A semiconductor solution is formed by applying a second ligand, which is a tertiary amine having a total of three or more functional groups, or a derivative thereof, and a ligand solution containing a second solvent to an assembly of semiconductor quantum dots. A ligand exchange step of exchanging the first ligand coordinated to the quantum dot with the second ligand.

  In general, semiconductor quantum dots dispersed in a solution generally have a relatively long molecular chain length ligand (first ligand). As a method of exchanging the ligand of the semiconductor quantum dot, after forming a film by coating a dispersion on a substrate while having a ligand molecule having a long molecular chain length, the ligand to be exchanged (second ligand) There is a method in which the ligand exchange treatment proceeds in a film state by applying a solution containing) or immersing the substrate in the solution. When such a method is used, the semiconductor film can be formed in a state where the quantum dots are not aggregated because the liquid state has a very long molecular chain.

In general, higher bonding strength is more efficient in replacing conventional long molecular chain ligands, and higher electrical conductivity can be obtained. In addition, when the semiconductor quantum dot material is changed, the specific ligand described above may change the value of the complex stability constant logβ, which is the ease of modification of the ligand molecule to the quantum dot. As the ligand (specific ligand), a material having a relatively short molecular chain length and easily coordinated can be applied to various quantum dot materials.
In principle, it is difficult to exchange 100% of all ligands, and sufficient characteristics can be obtained without exchanging all ligands. It is sufficient that the specific ligand is modified.

  In the method for producing a semiconductor film of the present invention, the semiconductor quantum dot assembly forming step and the ligand exchange step may be repeated, and further, a dispersion drying step for drying the semiconductor quantum dot dispersion, a ligand solution A solution drying step for drying the substrate, a washing step for washing the semiconductor quantum dot aggregate on the substrate, and the like. By repeating the semiconductor quantum dot assembly forming step and the ligand exchange step, the semiconductor films are stacked, and a semiconductor film having an arbitrary film thickness can be obtained.

  In the method for producing a semiconductor film of the present invention, a semiconductor quantum dot aggregate is formed on a substrate by applying a semiconductor quantum dot dispersion on the substrate in the semiconductor quantum dot aggregate formation step. At this time, since the semiconductor quantum dots are dispersed in the first solvent by the first ligand having a molecular chain length longer than that of the second ligand, the semiconductor quantum dots are less likely to be in an aggregated bulk shape. . Therefore, by applying the semiconductor quantum dot dispersion liquid onto the substrate, the semiconductor quantum dot aggregate can be configured so that the semiconductor quantum dots are arranged one by one.

Next, the first ligand coordinated to the semiconductor quantum dot and the second coordination by applying a solution of the specific ligand to the aggregate of semiconductor quantum dots by the ligand exchange step Ligand exchange with the child is performed. Here, the second ligand has a molecular chain length shorter than that of the first ligand, and has a total of three or more functional groups selected from SH, NH ₂ and OH. It is a tertiary amine or a derivative thereof, and is the specific ligand described above.
By ligand exchange, SH, NH ₂ and OH constituting the specific ligand are coordinated to the metal atom of the semiconductor quantum dot.

By the ligand exchange step, instead of the first ligand, the semiconductor quantum dot is configured with a second ligand (specific ligand) having a molecular chain length shorter than that of the first ligand. Since SH, NH ₂ , and OH that are coordinated to form coordinate bonds with the semiconductor quantum dots, it is considered that the semiconductor quantum dots are easily brought close to each other. When the semiconductor quantum dots are brought close to each other, it is considered that the electrical conductivity of the aggregate of semiconductor quantum dots is increased and a semiconductor film having a high photocurrent value can be obtained.
Furthermore, since it takes a tripod-type multidentate bonding mode, the proximity of quantum dots becomes extremely large, and as a result, the aggregate of semiconductor quantum dots becomes a strong semiconductor film and is unlikely to peel off from the substrate. It is done.
Hereinafter, each step will be specifically described.

[Semiconductor quantum dot assembly formation process]
In the semiconductor quantum dot assembly forming step, a semiconductor quantum dot dispersion liquid containing a semiconductor quantum dot, a first ligand coordinated to the semiconductor quantum dot, and a first solvent is applied on the substrate to form the semiconductor quantum dot To form an aggregate.
The semiconductor quantum dot dispersion liquid may be applied to the substrate surface, or may be applied to another layer provided on the substrate.
Examples of other layers provided on the substrate include an adhesive layer and a transparent conductive layer for improving the adhesion between the substrate and the assembly of semiconductor quantum dots.

-Semiconductor quantum dot dispersion-
The semiconductor quantum dot dispersion liquid contains a semiconductor quantum dot having a metal atom, a first ligand, and a first solvent.
The semiconductor quantum dot dispersion liquid may further contain other components as long as the effects of the present invention are not impaired.

(Semiconductor quantum dots)
The details of the semiconductor quantum dots containing metal atoms in the semiconductor quantum dot dispersion liquid are as described above, and the preferred embodiments are also the same.
In addition, the content of the semiconductor quantum dots in the semiconductor quantum dot dispersion liquid is preferably 1 mg / ml to 100 mg / ml, and more preferably 5 mg / ml to 40 mg / ml.
When the content of the semiconductor quantum dots in the semiconductor quantum dot dispersion liquid is 1 mg / ml or more, the semiconductor quantum dot density on the substrate is increased, and a good film is easily obtained. On the other hand, when the content of the semiconductor quantum dots is 100 mg / ml or less, the film thickness of the film obtained when the semiconductor quantum dot dispersion liquid is applied once is hardly increased. Therefore, the ligand exchange of the 1st ligand coordinated to the semiconductor quantum dot in a film | membrane can fully be performed.

(First ligand)
The first ligand contained in the semiconductor quantum dot dispersion liquid functions as a ligand coordinated to the semiconductor quantum dot and has a molecular structure that is likely to cause steric hindrance, and the semiconductor quantum in the first solvent. It also serves as a dispersant for dispersing dots.
The first ligand has a longer molecular chain length than the second ligand. The length of the molecular chain is determined by the length of the main chain when there is a branched structure in the molecule. As described above, the second ligand (specific ligand) is a tertiary amine having at least three kinds of functional groups selected from SH, NH ₂ and OH in total or a derivative thereof. Yes, it is not suitable as a ligand for dispersing semiconductor quantum dots in an organic solvent system. Here, “dispersion” refers to a state where there is no sedimentation or turbidity of particles.

From the viewpoint of improving the dispersion of the semiconductor quantum dots, the first ligand is preferably a ligand having at least 6 carbon atoms in the main chain, and a ligand having 10 or more carbon atoms in the main chain. Is more desirable.
Specifically, the first ligand may be either a saturated compound or an unsaturated compound. Decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, oleic acid, erucic acid, oleylamine , Dodecylamine, dodecanethiol, 1,2-hexadecanethiol, trioctylphosphine oxide, cetrimonium bromide and the like.
The first ligand is preferably one that hardly remains in the film when the semiconductor film is formed.
Among the above, the first ligand is preferably at least one of oleic acid and oleylamine, from the viewpoint of making the semiconductor quantum dots have dispersion stability and hardly remaining in the semiconductor film.

  The content of the first ligand in the semiconductor quantum dot dispersion is desirably 10 mmol / l to 200 mmol / l with respect to the total volume of the semiconductor quantum dot dispersion.

(First solvent)
The first solvent contained in the semiconductor quantum dot dispersion liquid is not particularly limited, but is preferably a solvent that hardly dissolves the semiconductor quantum dots and easily dissolves the first ligand. The first solvent is preferably an organic solvent, and specific examples include alkanes [n-hexane, n-octane, etc.], benzene, toluene and the like.
Only 1 type may be sufficient as a 1st solvent and the mixed solvent which mixed 2 or more types may be sufficient as it.

Among the above, the first solvent is preferably a solvent that hardly remains in the formed semiconductor film. If the solvent has a relatively low boiling point, the content of residual organic substances can be suppressed when the semiconductor film is finally obtained.
Furthermore, those with good wettability to the substrate are naturally preferable. For example, when coating on a glass substrate, alkanes such as hexane and octane are more preferable.

  The content of the first solvent in the semiconductor quantum dot dispersion is preferably 90% by mass to 98% by mass with respect to the total mass of the semiconductor quantum dot dispersion.

-Board-
The semiconductor quantum dot dispersion is applied on the substrate.
There is no restriction | limiting in particular about the shape of a board | substrate, a structure, a magnitude | size, It can select suitably according to the objective. The structure of the substrate may be a single layer structure or a laminated structure. As the substrate, for example, a substrate made of glass, an inorganic material such as YSZ (Yttria-Stabilized Zirconia), a resin, a resin composite material, or the like can be used. Among these, a substrate made of a resin or a resin composite material is preferable from the viewpoint of light weight and flexibility.

  The resins include polybutylene terephthalate, polyethylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polystyrene, polycarbonate, polysulfone, polyethersulfone, polyarylate, allyl diglycol carbonate, polyamide, polyimide, polyamideimide, polyetherimide, poly Fluorine resins such as benzazole, polyphenylene sulfide, polycycloolefin, norbornene resin, polychlorotrifluoroethylene, liquid crystal polymer, acrylic resin, epoxy resin, silicone resin, ionomer resin, cyanate resin, crosslinked fumaric acid diester, cyclic polyolefin, aromatic Synthetic resins such as aromatic ethers, maleimide-olefins, cellulose, episulfide compounds, etc.

  As a composite material of an inorganic material and a resin, a composite plastic material of a resin and the following inorganic material can be given. That is, composite plastic material of resin and silicon oxide particles, composite plastic material of resin and metal nanoparticles, composite plastic material of resin and inorganic oxide nanoparticles, composite plastic material of resin and inorganic nitride nanoparticles, Composite plastic material of resin and carbon fiber, Composite plastic material of resin and carbon nanotube, Composite plastic material of resin and glass ferrule, Composite plastic material of resin and glass fiber, Composite plastic material of resin and glass bead , Composite plastic material of resin and clay mineral, composite plastic material of resin and particles having mica derivative crystal structure, laminated plastic material having at least one bonding interface between resin and thin glass, inorganic layer and organic By laminating layers alternately, at least once Like composite materials having a barrier property having a bonding interface is.

  Using a stainless steel substrate or a metal multilayer substrate in which stainless steel and a dissimilar metal are laminated, an aluminum substrate, or an aluminum substrate with an oxide film whose surface insulation is improved by subjecting the surface to oxidation treatment (for example, anodization treatment). Also good.

A substrate made of resin or resin composite material (resin substrate or resin composite material substrate) is excellent in heat resistance, dimensional stability, solvent resistance, electrical insulation, workability, low air permeability, low moisture absorption, etc. It is preferable. The resin substrate and the resin composite material substrate may include a gas barrier layer for preventing permeation of moisture, oxygen, etc., an undercoat layer for improving the flatness of the resin substrate and the adhesion to the lower electrode, and the like. Good.
In addition, a lower electrode, an insulating film, or the like may be provided on the substrate. In that case, a semiconductor quantum dot dispersion liquid is applied to the lower electrode or the insulating film on the substrate.

  Although there is no restriction | limiting in particular in the thickness of a board | substrate, 50 micrometers-1000 micrometers are preferable, and it is more preferable that they are 50 micrometers-500 micrometers. When the thickness of the substrate is 50 μm or more, the flatness of the substrate itself is improved, and when the thickness of the substrate is 1000 μm or less, the flexibility of the substrate itself is improved and the semiconductor film can be used as a flexible semiconductor device. It becomes easier.

The method for applying the semiconductor quantum dot dispersion on the substrate is not particularly limited, and examples thereof include a method of applying the semiconductor quantum dot dispersion on the substrate, a method of immersing the substrate in the semiconductor quantum dot dispersion, and the like.
More specifically, as a method of applying the semiconductor quantum dot dispersion liquid on the substrate, spin coating method, dipping method, ink jet method, dispenser method, screen printing method, letterpress printing method, intaglio printing method, spray coating method, etc. The liquid phase method can be used.
In particular, the inkjet method, the dispenser method, the screen printing method, the relief printing method, and the intaglio printing method can form a coating film at an arbitrary position on the substrate and do not require a patterning step after the film formation. Therefore, the process cost can be reduced.

[Ligand exchange step]
In the ligand exchange step, the assembly of semiconductor quantum dots formed on the substrate by the semiconductor quantum dot assembly formation step has a molecular chain length shorter than that of the first ligand, and SH, NH ₂ and A secondary amine which is a tertiary amine having a total of three or more functional groups selected from OH or a derivative thereof, and a ligand solution containing a second solvent; The first ligand coordinated to the semiconductor quantum dot is exchanged for a second ligand (specific ligand).
When the first ligand is exchanged for a specific ligand, three or more functional groups of SH, NH ₂ and OH constituting the specific ligand are coordinated to the metal atom of the semiconductor quantum dot. To do.

-Ligand solution-
The ligand solution contains at least a second ligand (specific ligand) and a second solvent.
The ligand solution may further contain other components as long as the effects of the present invention are not impaired.

(Second ligand)
The second ligand is the specific ligand described above, and one having a molecular chain length shorter than that of the first ligand is used. The method for determining the length of the molecular chain length of the ligand is as described in the description of the first ligand.
The details of the specific ligand are also as described above.

  When alcohol is used as the second solvent contained in the ligand solution, the second ligand preferably has a hydroxy group (OH) in the molecule. When the second ligand has a hydroxy group in the molecular structure, miscibility with the alcohol can be increased, and ligand exchange can be performed efficiently.

  The content of the second ligand in the ligand solution is preferably 5 mmol / l to 200 mmol / l, more preferably 10 mmol to 100 mmol / l, based on the total volume of the ligand solution. .

(Second solvent)
The second solvent contained in the ligand solution is not particularly limited, but is preferably a solvent that easily dissolves the second ligand.
Such a solvent is preferably an organic solvent having a high dielectric constant, and examples thereof include ethanol, acetone, methanol, acetonitrile, dimethylformamide, dimethyl sulfoxide, butanol, and propanol.
Only 1 type may be sufficient as a 2nd solvent, and the mixed solvent which mixed 2 or more types may be sufficient as it.

Among the above, the second solvent is preferably a solvent that hardly remains in the formed semiconductor film. From the viewpoint of easy drying and easy removal by washing, alcohol or alkane having a low boiling point is preferable, and methanol, ethanol, n-hexane, or n-octane is more preferable.
In addition, the second solvent is preferably not mixed with the first solvent. For example, when an alkane such as hexane or octane is used as the first solvent, the second solvent is methanol or acetone. It is preferable to use a polar solvent such as
In addition, content of the 2nd solvent in a ligand solution is the remainder which deducted content of the specific ligand from the ligand solution total mass.

  The method for applying the ligand solution to the aggregate of semiconductor quantum dots is the same as the method for applying the semiconductor quantum dot dispersion on the substrate, and the preferred embodiment is also the same.

The semiconductor quantum dot assembly forming step and the ligand exchange step may be repeated. By repeating the semiconductor quantum dot assembly formation step and the ligand exchange step, the electrical conductivity of the semiconductor film having an assembly of semiconductor quantum dots coordinated with a specific ligand is increased, and the thickness of the semiconductor film is increased. Can be thickened.
The semiconductor quantum dot assembly formation step and the ligand exchange step may be repeated separately, but the ligand exchange step is performed after the semiconductor quantum dot assembly formation step is performed. It is preferable to repeat the cycle. By repeating the set of the semiconductor quantum dot assembly forming step and the ligand exchange step, unevenness of ligand exchange can be easily suppressed.
In addition, when performing a semiconductor quantum dot aggregate formation process and a ligand exchange process repeatedly, it is preferable to fully dry a film | membrane for every cycle.

It is expected that the photocurrent value of the semiconductor film increases as the exchange rate of the semiconductor quantum dot aggregate to the second ligand in the ligand exchange increases.
In addition, it is sufficient that the ligand exchange between the first ligand and the second ligand (specific ligand) of the semiconductor quantum dot is performed in at least a part of the semiconductor quantum dot assembly. , 100% (number) may not replace the specific ligand.

[Washing process]
Furthermore, the manufacturing method of the semiconductor film of this invention may have the washing | cleaning process of wash | cleaning the semiconductor quantum dot aggregate | assembly on a board | substrate.
By having the washing step, excess ligands and ligands desorbed from the semiconductor quantum dots can be removed. Further, the remaining solvent and other impurities can be removed. The cleaning of the semiconductor quantum dot aggregate is performed by pouring at least one of the first solvent and the second solvent on the semiconductor quantum dot aggregate, or by removing the substrate on which the semiconductor quantum dot aggregate or the semiconductor film is formed. What is necessary is just to immerse in at least one of 1 solvent and 2nd solvent.
The cleaning by the cleaning process may be performed after the semiconductor quantum dot assembly forming process or may be performed after the ligand exchange process. Moreover, you may carry out after the repetition of the set of a semiconductor quantum dot aggregate formation process and a ligand exchange process.

[Drying process]
The manufacturing method of the semiconductor film of this invention may have a drying process.
The drying step may be a dispersion drying step for drying the solvent remaining in the semiconductor quantum dot assembly after the semiconductor quantum dot assembly forming step, or the ligand solution may be replaced with a ligand solution after the ligand exchange step. It may be a solution drying step for drying. Moreover, the comprehensive process performed after the repetition of the set of a semiconductor quantum dot aggregate formation process and a ligand exchange process may be sufficient.

A semiconductor film is manufactured on the substrate through the steps described above.
The obtained semiconductor film has extremely high proximity between semiconductor quantum dots, high electrical conductivity, and a high photocurrent value. In addition, since the specific ligand has a high complex stability constant, the semiconductor film of the present invention composed of the semiconductor quantum dots and the specific ligand has stable coordination bonds, excellent film strength, Peeling is also suppressed.

<Electronic device>
Although the use of the semiconductor film of the present invention is not limited, the semiconductor film of the present invention has photoelectric conversion characteristics and hardly peels off, and thus can be suitably applied to various electronic devices having a semiconductor film or a photoelectric conversion film. .
Specifically, the semiconductor film of the present invention includes a photoelectric conversion film of a solar cell, a light emitting diode (LED), a semiconductor layer (active layer) of a thin film transistor, a photoelectric conversion film of an indirect radiation imaging apparatus, and a visible to infrared region. It can be suitably applied to a photodetector or the like.

<Solar cell>
A solar cell will be described as an example of an electronic device including the semiconductor film of the present invention or the semiconductor film manufactured by the method of manufacturing a semiconductor film of the present invention.
For example, a pn junction solar cell can be obtained by using a semiconductor film device having a pn junction including a p-type semiconductor layer including the semiconductor film of the present invention and an n-type semiconductor layer.
As a more specific embodiment of the pn junction solar cell, for example, a p-type semiconductor layer and an n-type semiconductor layer are provided adjacent to each other on a transparent conductive film formed on a transparent substrate. A form in which a metal electrode is formed on the n-type semiconductor layer can be mentioned.

An example of a pn junction solar cell will be described with reference to FIG.
FIG. 1 shows a schematic cross-sectional view of a pn junction solar cell 100 according to an embodiment of the present invention. A pn junction solar cell 100 includes a transparent substrate 10, a transparent conductive film 12 provided on the transparent substrate 10, a p-type semiconductor layer 14 formed of the semiconductor film of the present invention on the transparent conductive film 12, and p An n-type semiconductor layer 16 and a metal electrode 18 provided on the n-type semiconductor layer 16 are stacked on the type semiconductor layer 14.
When the p-type semiconductor layer 14 and the n-type semiconductor layer 16 are laminated adjacent to each other, a pn junction solar cell can be obtained.

As the transparent substrate 10, the same material as the substrate used in the method for producing a semiconductor film of the present invention can be used as long as it is transparent. Specifically, a glass substrate, a resin substrate, etc. are mentioned.
Examples of the transparent conductive film 12 include films made of In ₂ O ₃ : Sn (ITO), SnO ₂ : Sb, SnO ₂ : F, ZnO: Al, ZnO: F, CdSnO _{4, and the} like.

As described above, the semiconductor film of the present invention is used for the p-type semiconductor layer 14.
The n-type semiconductor layer 16 is preferably a metal oxide. Specific examples include metal oxides containing at least one of Ti, Zn, Sn, and In, and more specific examples include TiO ₂ , ZnO, SnO ₂ , and IGZO. The n-type semiconductor layer is preferably formed by a wet method (also referred to as a liquid phase method) in the same manner as the p-type semiconductor layer from the viewpoint of manufacturing cost.
As the metal electrode 18, Pt, Al, Cu, Ti, Ni, or the like can be used.

  Examples will be described below, but the present invention is not limited to these examples.

<Fabrication of semiconductor film device>
[Preparation of Semiconductor Quantum Dot Dispersion 1]
First, a PbS particle dispersion in which PbS particles were dispersed in toluene was prepared. As the PbS particle dispersion, PbS core Evidot (nominal particle size 3.3 nm, 20 mg / ml, solvent toluene) manufactured by Evident Technology was used.
Next, 2 ml of the PbS particle dispersion was taken into the centrifuge tube, 38 μl of oleic acid was added, and then 20 ml of toluene was added to dilute the concentration of the dispersion. Thereafter, ultrasonic dispersion was performed on the PbS particle dispersion, and the PbS particle dispersion was thoroughly stirred. Next, 40 ml of ethanol was added to the PbS particle dispersion, followed by ultrasonic dispersion, and centrifugation was performed at 10,000 rpm, 10 minutes, and 3 ° C. After discarding the supernatant in the centrifuge tube, 20 ml of octane was added to the centrifuge tube and subjected to ultrasonic dispersion to disperse the precipitated quantum dots well in octane. The obtained dispersion was concentrated using a rotary evaporator (35 hpa, 40 ° C.), and as a result, about 4 ml of semiconductor quantum dot dispersion 1 (octane solvent) having a concentration of about 10 mg / ml was obtained.
When the particle size of the PbS particles contained in the semiconductor quantum dot dispersion 1 was measured with a STEM (Scanning Transmission Electron Microscope) and analyzed with image confirmation software, the average particle size was 3.2 nm. .

[Preparation of Semiconductor Quantum Dot Dispersion 2]
First, InP particles were synthesized, and an octane dispersion of InP particles coordinated with oleylamine was prepared.

-Preparation of octane dispersion of oleylamine modified InP particles-
In a glove box under a N ₂ gas atmosphere, put 30 ml of 1-octadecene, 1.81 ml of oleylamine, 0.60 g of anhydrous indium chloride, 0.49 ml of trisdimethylaminophosphine, and a magnetic stirring bar in a three-necked round bottom flask. It was. Next, the three-necked round bottom flask was taken out from the glove box in a state of being sealed with a stopper with a three-way valve, and set in an aluminum block thermostat with a magnetic stirrer. Thereafter, the three-way valve was operated, N ₂ gas was passed through the flask, and heating of the aluminum block thermostatic bath was started while the mixture was vigorously stirred with a magnetic stirring bar. The temperature of the aluminum block thermostat was raised to 150 ° C. in about 30 minutes and held there for 5 hours. Thereafter, the heating was stopped, and the three-necked round bottom flask was cooled to room temperature using a blower fan.

The product was taken out from the three-necked round bottom flask, and unreacted products and by-products were removed by centrifugation using a centrifuge. The product (InP particles) was purified using ultra-dehydrated toluene as a good solvent and dehydrated ethanol as a poor solvent. Specifically, the process of dissolving the product in a good solvent, redispersing the dissolved InP particles in a poor solvent, and centrifuging the resulting InP particle dispersion was repeated. An ultrasonic cleaner was used for redispersion. After repeated centrifugation of the InP particle dispersion, dehydrated ethanol remaining in the InP particle dispersion was removed by distillation under reduced pressure using a rotary evaporator. Finally, an octane dispersion (semiconductor quantum dot dispersion 2) having an oleylamine-modified InP particle concentration of 1 mg / ml in which the extracted InP particles were dispersed in octane was obtained.
When the obtained InP particles were observed with a STEM, the average particle diameter was about 4 nm.

(Preparation of ligand solution)
1 mmol of the compound shown in the “exchange ligand” column of Table 1 was separated and dissolved in 10 ml of methanol to prepare a ligand solution having a concentration of 0.1 mol / l. In order to promote the dissolution of the ligand in the ligand solution, ultrasonic irradiation was performed so that the ligand remained as little as possible.

〔substrate〕
As the substrate, a substrate having 65 pairs of comb-shaped platinum electrodes shown in FIG. 2 on a quartz glass was prepared. As the comb-type platinum electrode, a comb-type electrode (model number 012126, electrode interval 5 μm) manufactured by BAS was used.

[Manufacture of semiconductor films]
(1) Semiconductor quantum dot aggregate formation process The prepared semiconductor quantum dot dispersion liquid 1 was dropped on a substrate and spin-coated at 2500 rpm to obtain a semiconductor quantum dot aggregate film.

(2) Ligand exchange step Further, a methanol solution [ligand solution] of the ligands shown in Table 1 is dropped on the semiconductor quantum dot assembly film, and then spin-coated at 2500 rpm to form the semiconductor film. Obtained.

(3) Cleaning process 1
Next, only methanol, which is a solvent for the ligand solution, was dropped on the semiconductor film and spin-coated.

(4) Cleaning process 2
Furthermore, only the octane solvent was dropped on the semiconductor film after the cleaning in the cleaning step 1 and spin-coated.

By repeating the series of steps (1) to (4) for 15 cycles, a semiconductor film having a thickness of 100 nm made of an assembly of PbS quantum dots and subjected to ligand exchange was obtained.
As described above, a semiconductor film device having a semiconductor film on a substrate was produced.

  The exchange ligands contained in the ligand solutions used in Examples and Comparative Examples are as shown in Table 1. In the column of “p, q, r” in Table 1, when one numerical value is described, it means that p, q, and r are all the same number in the general formula (A).

  In the semiconductor quantum dot assembly forming step, only the quantum dot dispersion liquid 1 (PbS) was changed to the quantum dot dispersion liquid 2 (InP) to obtain a semiconductor quantum dot assembly film made of InP quantum dots.

<Evaluation of semiconductor film>
Various evaluation was performed about the semiconductor film of the obtained semiconductor film device.

1. Electrical conductivity The electrical conductivity of the semiconductor film was evaluated by using a semiconductor parameter analyzer for the produced semiconductor film device.
First, the voltage applied to the electrode was swept between −5 to 5 V without irradiating the semiconductor film device with light, and the IV characteristics in the dark state were obtained. The current value with a +5 V bias applied was adopted as the dark current value Id.
Next, to evaluate the photocurrent values while irradiating monochromatic light (irradiation intensity 10 ¹³ photons) to the semiconductor film device. Note that the apparatus shown in FIG. 3 was used to irradiate the semiconductor film device with monochromatic light. The wavelength of the monochromatic light was systematically changed between 280 nm and 700 nm. The increase in current from the dark current when irradiating light with a wavelength of 280 nm was taken as the photocurrent value Ip.
The evaluation results are shown in Tables 1 and 2.

2. Film peeling from substrate For the semiconductor film devices of Examples and Comparative Examples, the film peeling of the semiconductor film was evaluated by visual observation. Tables 1 and 2 show the presence or absence of film peeling.

As shown in Table 1, by modifying the ligand molecule represented by the general formula (A) to PbS by ligand exchange, a high photocurrent value is obtained for the ethanedithiol-modified semiconductor film (Comparative Example 4). It was found that dark current can be obtained. In addition, the ethanedithiol-modified semiconductor film showed remarkable film peeling with the naked eye, whereas the ligand molecules of the examples did not show film peeling and achieved high roughness.
Also, in the case of ethylenediamine, which is also an amine type (Comparative Example 5), it was found that both the photocurrent value and the dark current are significantly reduced. Therefore, this result suggests that good electrical conductivity characteristics cannot be obtained in the case of a diamine having a plurality of amine groups. It is considered that logβ is not so high as a factor, and ligand coordination is not progressing much. Therefore, it seems that oleic acid remains as a ligand molecule and inhibits carrier transport between quantum dots.
Further, when CTAB (cetyltrimethylammonium bromide) which is quaternary ammonium was used (Comparative Example 6), high electrical conductivity was not obtained.
It has been shown that high photocurrent and electrical conductivity can be realized by producing a semiconductor film in which a specific ligand is modified on a semiconductor quantum dot as described above.

  In addition, from the example in which the quantum dot material shown in Table 2 is InP, the quantum dot film in which the specific ligand of the present invention is coordinated also in the InP system has higher electrical conductivity than the comparative example. It can be seen that the knowledge obtained in the present invention can be applied even if the quantum dot material is changed.

14 p-type semiconductor layer 16 n-type semiconductor layer 100 pn junction solar cell

Claims (24)

An assembly of semiconductor quantum dots containing metal atoms;
At least one ligand selected from the group consisting of tertiary amines coordinated to the semiconductor quantum dots and having a total of three or more functional groups selected from SH, NH ₂ and OH, and derivatives thereof When,
A semiconductor film. The semiconductor film according to claim 1, wherein the ligand is represented by the following general formula (A).

(In formula (A), X ¹ , X ² and X ³ each independently represent SH, NH ₂ or OH, and p, q and r each independently represent an integer of 1 or more and 4 or less.) The semiconductor film according to claim 2, further comprising a substituent having 10 or less atoms in at least one of (CH ₂ ) p, (CH ₂ ) q, and (CH ₂ ) r in the general formula (A).   The semiconductor film according to claim 3, wherein the substituent has 7 or less atoms. The semiconductor film according to claim 2, wherein (CH ₂ ) p, (CH ₂ ) q, and (CH ₂ ) r in the general formula (A) are all unsubstituted.   The semiconductor film according to claim 1, wherein the ligand is tris (2-aminoethyl) amine or a derivative thereof.   The said ligand is represented by the said general formula (A), The tripod type coordination is carried out with respect to the metal atom in the said semiconductor quantum dot. Semiconductor film.   The semiconductor film according to claim 1, wherein the semiconductor quantum dot includes at least one selected from PbS, PbSe, InN, InAs, InSb, and InP.   The semiconductor film according to claim 1, wherein the semiconductor quantum dots have an average particle size of 2 nm or more and 15 nm or less.   The semiconductor film according to claim 8, wherein the semiconductor quantum dot includes PbS. An assembly of semiconductor quantum dots by applying a semiconductor quantum dot dispersion containing a semiconductor quantum dot containing a metal atom, a first ligand coordinated to the semiconductor quantum dot, and a first solvent on a substrate Forming a semiconductor quantum dot assembly to form
A tertiary amine having a molecular chain length shorter than that of the first ligand and having a total of three or more functional groups selected from SH, NH ₂ and OH, or a derivative thereof; And the first ligand that is coordinated to the semiconductor quantum dot by applying the ligand solution containing the ligand and the second solvent to the assembly of the semiconductor quantum dots. A ligand exchange step for exchanging the two ligands;
The manufacturing method of the semiconductor film which has this. The method for producing a semiconductor film according to claim 11, wherein the second ligand is represented by the following general formula (A).

(In formula (A), X ¹ , X ² and X ³ each independently represent SH, NH ₂ or OH, and p, q and r each independently represent an integer of 1 or more and 4 or less.) Formula in (A) _(CH 2) p, _(CH 2) production of q and _(CH 2) at least one of r, the semiconductor film of claim 12 further comprising the atomic number 10 following substituents Method.   The method for manufacturing a semiconductor film according to claim 13, wherein the substituent has 7 or less atoms. The method for producing a semiconductor film according to claim 12, wherein (CH ₂ ) p, (CH ₂ ) q, and (CH ₂ ) r in the general formula (A) are all unsubstituted.   The method for producing a semiconductor film according to any one of claims 11 to 15, wherein the second ligand is tris (2-aminoethyl) amine or a derivative thereof.   The said 2nd ligand is a ligand which is represented by the said general formula (A), and is a tripod type coordination with respect to the metal atom in the said semiconductor quantum dot. A method for producing a semiconductor film according to claim 1.   18. The method of manufacturing a semiconductor film according to claim 11, wherein the semiconductor quantum dots include at least one selected from PbS, PbSe, InN, InAs, InSb, and InP.   The method of manufacturing a semiconductor film according to claim 11, wherein the semiconductor quantum dots have an average particle diameter of 2 nm or more and 15 nm or less.   The method of manufacturing a semiconductor film according to claim 18, wherein the semiconductor quantum dots contain PbS.   A solar cell provided with the semiconductor film of any one of Claims 1-10.   A light emitting diode provided with the semiconductor film of any one of Claims 1-10.   A thin-film transistor provided with the semiconductor film of any one of Claims 1-10.   An electronic device provided with the semiconductor film of any one of Claims 1-10.