JP2019021887A - Electron transport layer and method for producing electron transport layer - Google Patents

Abstract

An electron transporting material which can be oriented near parallel to a substrate and has high transparency, and a method for forming an electron transporting layer are provided.
SOLUTION: After dissolving a predetermined substituent in an imide group of a benzoisoquinoline derivative such as naphthalenediimide in an organic solvent and applying the solution to a substrate, for example, annealing is performed to convert the substituent. Thus, an electron transport layer containing a benzoisoquinoline derivative can be obtained.
[Selection figure] None

Description

  The present invention basically relates to an electron transport layer in which the orientation of an electron transport material is controlled, and a method for forming an electron transport layer. The present invention further relates to a solar cell or an organic EL device including an electron transport layer having controlled orientation.

  Japanese Patent Application Laid-Open No. 2017-59668 (Patent Document 1) describes a benzothiazole compound and an organic thin film solar cell. When the benzothiazole compound described in Patent Document 1 is used as an electron transport material, it is oriented in a random direction with respect to the substrate. For this reason, the electron transport layer containing this compound does not have high electron transport ability. Moreover, this compound has a color scheme peculiar to thiazole compounds, and is not highly transparent.

  International Publication WO2017-104792 pamphlet (Patent Document 2) describes a perovskite solar cell. The electron transport layer is a layer constituting a perovskite solar cell.

JP 2017-59668 A International Publication WO2017-104792 Pamphlet

  An object of the present invention is to provide an electron transporting layer that can orient an electron transporting material near parallel to a substrate and has high transparency, and a method for forming an electron transporting layer.

  The present invention is basically an embodiment in which an electron transport layer can be formed in a controlled state so as to have a parallel orientation with respect to a substrate if it is a predetermined benzoisoquinoline derivative or a predetermined naphthalenediimide derivative. Based on the findings by In particular, in the present invention, a substituent is introduced into a nitrogen atom constituting the above derivative to apply a coating solution in a state where the solubility of the above derivative is enhanced to the substrate, and a desubstitution treatment (deprotection treatment) is performed. Therefore, it is based on the knowledge that an electron transport layer excellent in orientation and transparency can be obtained.

  The present invention provides an electron transport layer comprising a benzoisoquinoline derivative represented by the formula (I).

In the formula (I), X ¹ and X ² may be the same or different and each represents O, S, Se, or Te.
Y ¹ is a hydrogen atom, a methyl group, a fluorine atom, or a chlorine atom.
R ^{1 to} R ⁴ may be the same or different and are a hydrogen atom, a C _{1 to} C ₆ alkyl group, a C _{1 to} C ₆ alkoxy group, a cyano group, a nitro group, a fluorine atom, or a chlorine atom,
R ¹ and R ² and R ³ and R ⁴ may be substituted with a halogen atom, a C _{1 to} C ₆ alkyl group, or a C _{1 to} C ₆ alkoxy group together with the bonded atoms. C ₃ -C ₁₂ cycloalkyl group, C ₆ -C ₁₄ aryl group, C ₈ -C ₁₄ aralkyl group, C ₃ -C ₁₂ heterocycloalkyl group, C ₆ -C ₁₄ heteroaryl group, C ₃ -C ₁₂ heterocycloalkyl _group, C 6 _{-C 14} heteroaryl _group, a C 8 _{-C 14} heteroaralkyl group, or _C 3 _{-C 14} heterocyclyl group.
R ¹¹ and R ^{12, which} may be the same or different, are a hydrogen atom, a methyl group, a methoxy group, a cyano group, a nitro group, a fluorine atom, or a chlorine atom, or bonded atoms and those atoms, respectively. Together with the intervening atoms, it constitutes any group selected from group A below.

Group A

In the formulas (Ia) to (Im),
X ³ and X ⁴ may be the same or different and represent O, S, Se, or Te.
X ¹¹ represents O or S.
Y ² is a hydrogen atom, a methyl group, a fluorine atom, or a chlorine atom.
R ¹³ and R ¹⁴ may be the same or different and are a hydrogen atom, a methyl group, a methoxy group, a cyano group, a nitro group, a fluorine atom, or a chlorine atom.

A preferred example of the electron transporting layer is that in which the benzoisoquinoline derivative represented by the formula (I) is a naphthalenediimide derivative represented by the formula (II).

In formula (II), X ^{1 to} X ⁴ may be the same or different and represent O, S, Se, or Te.
Y ¹ and Y ² may be the same or different and are a hydrogen atom, a methyl group, a fluorine atom, or a chlorine atom.
R ^{1 to} R ⁴ may be the same or different and are a hydrogen atom, a methyl group, a methoxy group, a cyano group, a nitro group, a fluorine atom, or a chlorine atom,
R ¹ and R ² and R ³ and R ⁴ may be substituted with a halogen atom, a C _{1 to} C ₆ alkyl group, or a C _{1 to} C ₆ alkoxy group together with the bonded atoms. C ₃ -C ₁₂ cycloalkyl group, C ₆ -C ₁₄ aryl group, C ₈ -C ₁₄ aralkyl group, C ₃ -C ₁₂ heterocycloalkyl group, C ₆ -C ₁₄ heteroaryl group, C ₃ -C ₁₂ heterocycloalkyl _group, C 6 _{-C 14} heteroaryl _group, a C 8 _{-C 14} heteroaralkyl group, or _C 3 _{-C 14} heterocyclyl group.

A preferable example of the electron transport layer is a compound in which the benzoisoquinoline derivative represented by the formula (I) is represented by the formula (III).

  The present invention also provides a solar cell including the above-described compound or electron transport layer.

  The present invention also provides an organic electroluminescence device including the above-described compound or electron transport layer.

Next, the present invention provides a method for manufacturing an electron transport layer.
This method includes a solution coating step and a substituent removal step.
The solution application step is a step of applying a solution containing a benzoisoquinoline derivative represented by the formula (I ′) to a substrate to form a coating film.
The substituent removal step is a step for modifying the benzoisoquinoline derivative represented by the formula (I ′) to the benzoisoquinoline derivative represented by the formula (I) after the solution coating step.

In the formula (I) and the formula (I ′), X ¹ and X ² may be the same or different and represent O, S, Se, or Te.
Y ¹ is a hydrogen atom, a methyl group, a fluorine atom, or a chlorine atom.
R ¹ to R ^4, which may be the same or different, a hydrogen _atom, C 1 -C ₆ alkyl _group, C 1 -C6 alkoxy group, a cyano group, a nitro group, a fluorine atom, or a chlorine atom,
R ¹ and R ² and R ³ and R ⁴ may be substituted with a halogen atom, a C _{1 to} C ₆ alkyl group, or a C _{1 to} C ₆ alkoxy group together with the bonded atoms. A good 3-10 membered cyclyl group, 5-10 membered aryl group, 3-10 membered heterocyclyl group or 5-10 membered heteroaryl group is shown.
R ¹¹ and R ¹² may be the same or different and are a hydrogen atom, a methyl group, a methoxy group, a cyano group, a nitro group, a fluorine atom, or a chlorine atom, or bonded atoms and Together with the intervening atoms, it constitutes any group selected from group A.
PG ¹ represents tert-butoxycarbonyl group, 2,2,2-trichloroethoxycarbonyl group, methoxycarbonyl group, ethoxycarbonyl group; benzyloxycarbonyl group, paramethoxybenzyloxycarbonyl group, para (or ortho) nitrobenzyloxycarbonyl Group: benzyl group, 4-methoxybenzyl group, triphenylmethyl group; formyl group, acetyl group; benzoyl group; 2,4-dinitrobenzenesulfonyl group, or orthonitrobenzenesulfonyl group.

  In this method, the substituent removal step may include an acid contact step in which an acid is brought into contact with the coating film, and a step of bringing the coating film to 100 ° C. or more and 200 ° C. or less.

The present invention also provides a method for manufacturing a solar cell. This method includes a step of forming an electron transport layer on a substrate using the method for manufacturing an electron transport layer described above,
Forming a light absorption layer on the electron transport layer;
Forming a hole transport layer on the light absorption layer;
Forming an electrode on the hole transport layer.

  In the present invention, by using a predetermined benzoisoquinoline derivative or a predetermined naphthalenediimide derivative as an electron transporting material, the electron transporting material can be oriented near parallel to the substrate, and the electron transporting layer having high transparency can be used. , A method for forming an electron transport layer can be provided.

FIG. 1 is a graph instead of a drawing showing the results of thermogravimetry in the examples. FIG. 2 is a graph replaced with a drawing showing ultraviolet-visible absorption characteristics in the examples. FIG. 3 is a graph instead of a drawing showing measurement results by polarized infrared polygonal incidence spectroscopy in the examples. The upper part of FIG. 3 shows the spectrum of Boc-protected naphthalene diimide, and the lower part of FIG. 3 shows the spectrum of naphthalene diimide. FIG. 4 shows a study on the angle between the compound and the substrate derived from the measurement result by polarized infrared polygonal incidence spectroscopy. FIG. 5 is a conceptual diagram showing the configuration of the solar cell in the example. FIG. 6 is a graph instead of a drawing showing the current density-voltage characteristics of the perovskite solar cells obtained in the examples.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below, but includes those appropriately modified by those skilled in the art from the following embodiments.

  The present invention relates to an electron transport layer containing a benzoisoquinoline derivative represented by the formula (I) (the compound of the present invention).

In the formula (I), X ¹ and X ² may be the same or different and each represents O, S, Se, or Te.
Y ¹ is a hydrogen atom, a methyl group, a fluorine atom, or a chlorine atom.
R ^{1 to} R ⁴ may be the same or different and are a hydrogen atom, a C _{1 to} C ₆ alkyl group, a C _{1 to} C ₆ alkoxy group, a cyano group, a nitro group, a fluorine atom, or a chlorine atom,
R ¹ and R ² and R ³ and R ⁴ may be substituted with a halogen atom, a C _{1 to} C ₆ alkyl group, or a C _{1 to} C ₆ alkoxy group together with the bonded atoms. C ₃ -C ₁₂ cycloalkyl group, C ₆ -C ₁₄ aryl group, C ₈ -C ₁₄ aralkyl group, C ₃ -C ₁₂ heterocycloalkyl group, C ₆ -C ₁₄ heteroaryl group, C ₃ -C ₁₂ heterocycloalkyl _group, C 6 _{-C 14} heteroaryl _group, a C 8 _{-C 14} heteroaralkyl group, or _C 3 _{-C 14} heterocyclyl group.
R ¹¹ and R ^{12, which} may be the same or different, are a hydrogen atom, a methyl group, a methoxy group, a cyano group, a nitro group, a fluorine atom, or a chlorine atom, or bonded atoms and those atoms, respectively. Together with the intervening atoms, it constitutes any group selected from group A below.

Group A

In the formulas (Ia) to (Im),
X ³ and X ⁴ may be the same or different and represent O, S, Se, or Te.
X ¹¹ represents O or S.
Y ² is a hydrogen atom, a methyl group, a fluorine atom, or a chlorine atom.
R ¹³ and R ¹⁴ may be the same or different and are a hydrogen atom, a methyl group, a methoxy group, a cyano group, a nitro group, a fluorine atom, or a chlorine atom.

In formula (I), preferred examples of X ¹ and X ² are O or S.
A preferred example of Y ¹ is a hydrogen atom.
Preferred examples of R ^{1 to} R ⁴ are a hydrogen atom, a methyl group, an ethyl group, a methoxy group, a cyano group, a nitro group, a fluorine atom, or a chlorine atom, and a hydrogen atom is preferred.
Preferred examples of R ¹¹ and R ¹² constitute any group selected from group A. Among group A, those constituting the group represented by Ia are preferred.
Preferred examples of X ³ and X ⁴ are O or S.
A preferred example of Y ² is a hydrogen atom.

“C ₁ -C ₆ alkyl group” means a straight or branched saturated hydrocarbon group having 1 to 6 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, or an n-butyl group. , Sec-butyl group, tert-butyl group, isobutyl group, n-pentyl group, n-hexyl group, 1-ethylpropyl group, 2,2-dimethylpropyl group, and the like.

“C ₁ -C ₆ alkoxy group” means a linear or branched alkyloxy group having 1 to 6 carbon atoms, such as a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a tert- Examples include butoxy group.

“C ₃ -C ₁₂ cycloalkyl group” means a saturated hydrocarbon ring having 3 to 12 carbon atoms, and is exemplified by a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and the like. In addition to the monocycloalkyl group, a polycycloalkyl group such as a bicycloalkyl group or a tricycloalkyl group is also included. As the bicycloalkyl group, a norbornyl group such as an exo-2-norbornyl group, endo- 2-norbornyl group, 3-pinanyl group, bicyclo [3.1.0] hexyl group, bicyclo [2.2.1] heptyl group, bicyclo [2.2.2] oct-2-yl group, etc. Examples of the alkyl group include an adamantyl group such as a 1-adamantyl group and a 2-adamantyl group.

The “C ₆ -C ₁₄ aryl group” means an aryl group having 6 to 14 carbon atoms, and examples thereof include a phenyl group, a naphthyl group, an anthryl group, and a phenanthryl group.

The “C ₈ -C ₁₄ aralkyl group” means an alkyl group having 8 to 14 carbon atoms in which one of alkyl hydrogen atoms is replaced by an aryl group.

The “C ₃ -C ₁₂ heterocycloalkyl group” is a C ₃ -C ₁₂ in which one or more carbon atoms constituting the cyclo ring are substituted by an atom selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom. Means a cycloalkyl group;

The “C ₆ -C ₁₄ heteroaryl group” is a C ₆ -C ₁₄ aryl group in which one or more carbon atoms constituting aryl are substituted by an atom selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom. Means. Examples of heteroaryl are furan, benzofuran, thiophene, benzothiophene, pyrrole, pyridine, pyrimidine, pyridazine, pyrazine, quinoline, isoquinoline, phthalazine, benzo-1,2,5-thiadiazole, benzothiazole, indole, benzotriazole, benzo Dioxolane, benzodioxane, benzimidazole, carbazole and quinazoline.

The “C ₈ -C ₁₄ heteroaralkyl group” means an alkyl group having 8 to 14 carbon atoms in which one of the alkyl hydrogen atoms is replaced by a heteroaryl group.

  “Heterocyclyl” is a monocyclic or bicyclic 3 to 10 membered saturated or unsaturated heterocyclic ring containing 1 to 3 atoms selected from the group consisting of a nitrogen atom, an oxygen atom and a sulfur atom Meaning aziridinyl, azetidinyl, pyrrolidinyl, morpholinyl, pyrrolyl, furyl, thienyl, pyrazolyl, imidazolyl, oxazolyl, isothiazolyl, pyranyl, pyridyl, pyridazinyl, pyrimidinyl Group, pyrazinyl group, benzimidazolyl group, benzoxazolyl group, quinolyl group, pyrrolinyl group, imidazolinyl group, pyrazolinyl group, dihydropyridyl group, tetrahydropyridyl group and the like. A heterocyclyl group may include a heterocycloalkyl group and a heteroaryl group.

In the benzoisoquinoline derivative represented by the formula (I), an electron withdrawing group is bonded to the ring. For this reason, the LUMO (lowest unoccupied orbital) energy ranking of this derivative is lowered, and as a result, it becomes easier to receive electrons and becomes a good acceptor. From such a viewpoint, a preferable example of X ¹ and X ² is O, and in this case, a carbonyl group is bonded to the ring. From this point of view, R ^{1 to} R ⁴ may be a cyano group, a nitro group, a fluorine atom, or a chlorine atom, but considering the size of the molecule, R ^{1 to} R ⁴ are hydrogen atoms. Also good.

  The benzoisoquinoline derivative represented by the formula (I) is excellent in transparency. Further, as shown in Examples described later, the benzoisoquinoline derivative represented by the formula (I) exhibits an orientation that is not perpendicular to the substrate (an orientation that is nearly parallel to the substrate). This means that the electron transport layer containing this compound is excellent in electron transfer in the direction perpendicular to the substrate. For this reason, the electron transport layer containing the compound represented by the formula (I) has various advantages in practical use, such as being able to reduce the film thickness.

A preferred example of the electron transporting layer is that in which the benzoisoquinoline derivative represented by the formula (I) is a naphthalenediimide derivative represented by the formula (II). In the following, in the formula (I), the group A constitutes a group represented by Ia.

In formula (II), X ^{1 to} X ⁴ may be the same or different and represent O, S, Se, or Te.
Y ¹ and Y ² may be the same or different and are a hydrogen atom, a methyl group, a fluorine atom, or a chlorine atom.
R ^{1 to} R ⁴ may be the same or different and are a hydrogen atom, a methyl group, a methoxy group, a cyano group, a nitro group, a fluorine atom, or a chlorine atom,
R ¹ and R ² and R ³ and R ⁴ may be substituted with a halogen atom, a C _{1 to} C ₆ alkyl group, or a C _{1 to} C ₆ alkoxy group together with the bonded atoms. C ₃ -C ₁₂ cycloalkyl group, C ₆ -C ₁₄ aryl group, C ₈ -C ₁₄ aralkyl group, C ₃ -C ₁₂ heterocycloalkyl group, C ₆ -C ₁₄ heteroaryl group, C ₃ -C ₁₂ heterocycloalkyl _group, C 6 _{-C 14} heteroaryl _group, a C 8 _{-C 14} heteroaralkyl group, or _C 3 _{-C 14} heterocyclyl group.

In formula (II), preferred examples of X ¹ and X ² are O or S, with O being most preferred.
A preferred example of Y ¹ is a hydrogen atom, but it may be a group substituted by a protecting group or the like.
Preferred examples of R ^{1 to} R ⁴ are a hydrogen atom, a methyl group, an ethyl group, a methoxy group, a cyano group, a nitro group, a fluorine atom, or a chlorine atom, and a hydrogen atom is preferred. However, in R ^{1 to} R ⁴ , adjacent atoms may serve as a linking group, and may constitute a bond with another benzoisoquinoline derivative. R ^{1 to} R ⁴ may be a cyano group, a nitro group, a fluorine atom, or a chlorine atom from the viewpoint that the energy order of LUMO is lowered by bonding an electron withdrawing group to the ring.
Preferred examples of X ³ and X ⁴ are O or S, with O being most preferred.
A preferred example of Y ² is a hydrogen atom.

A preferable example of the electron transporting layer is that in which the benzoisoquinoline derivative represented by the formula (I) is a compound represented by the formula (III) (naphthalenediimide).

  In naphthalene diimide, four carbonyl groups that are electron withdrawing groups are bonded to a naphthalene ring in one molecule. For this reason, the LUMO energy ranking of this derivative is lowered, and as a result, it becomes easier to receive electrons and becomes a good acceptor. Naphthalene diimide has excellent transparency and is easy to synthesize. On the other hand, naphthalene diimide is difficult to dissolve in organic solvents. For this reason, conventionally, an electron transport layer could not be obtained by dissolving naphthalenediimide in an organic solvent and applying the solution.

Polymer System This specification has a basic structure of a benzoisoquinoline derivative represented by the formula (I), a polymer in which a plurality of benzoisoquinoline derivatives represented by the formula (I) are linked, and a plurality of benzoisoquinoline derivatives represented by the formula (I). A polymer having a basic structure in which an isoquinoline derivative is bonded to another basic structure is also provided. The present specification also provides an electron transport layer using such a polymer, a solar cell including the electron transport layer, an organic EL element including the electron transport layer, and a method for producing them. That is, the polymer having the basic structure of the benzoisoquinoline derivative represented by the formula (I) has poor solubility in an organic solvent. On the other hand, in the present invention, a hydrogen atom or the like connected to a nitrogen molecule constituting an imide bond (imide group) is once replaced with another group and dissolved in an organic solvent to obtain a coating film. Then, the imide bond etc. are revived by removing the replaced group. Thus, the solubility of the polymer which is difficult to dissolve in the organic solvent can be improved, a coating film can be formed, and an electron transport layer can be obtained. This concept can be widely used for molecules and polymers having imide bonds that can be used as electron transport materials. In this case, R ^{1 to} R ⁴ of the benzoisoquinoline derivative represented by the formula (I) may serve as a linking group and be linked to another benzoisoquinoline derivative to constitute a polymer. R ¹ and R ² , and R ³ and R ⁴ may be combined with the bonded atoms to form a linking group and be linked with other benzoisoquinoline derivatives to constitute a polymer. In addition, the structure of the polymer may be determined by hydrogen atoms existing in Y ¹ and Y ² being bonded to X ^{1 to} X ⁴ of other benzoisoquinoline derivatives by hydrogen bonds or van der Waals forces. In addition, a polymer containing a plurality of benzoisoquinoline derivatives represented by the formula (I) has a plurality of core groups, and R ¹ and R ² , or R ³ and R ⁴ are bonded to the core groups. By doing so, the polymer may have a regular molecular structure. Examples of polymers constituting a two-dimensional π-electron sheet that can be extended to the concept of the present invention are shown below.

  Next, a solar cell containing the compound of the present invention (particularly a perovskite solar cell) and an electron transport layer containing the compound of the present invention will be described.

  The perovskite solar cell of the present invention includes, for example, a transparent electrode, an electron transport layer, a perovskite layer (light absorption layer), a hole transport layer, and a metal electrode in this order.

Transparent electrode The transparent electrode is a support for the electron transport layer and is a layer having a function of taking out current (electrons) from the perovskite layer (light absorption layer) through this layer. Therefore, a conductive substrate is preferable, A transparent conductive layer having translucency capable of transmitting light contributing to photoelectric conversion is preferable.

Examples of the transparent conductive layer include a tin-doped indium oxide (ITO) film, an impurity-doped indium oxide (In ₂ O ₃ ) film, an impurity-doped zinc oxide (ZnO) film, a fluorine-doped tin dioxide (FTO) film, Examples include a laminated film formed by laminating these. The thickness of these transparent conductive layers is not particularly limited, and is usually preferably adjusted so that the resistance is 5 to 15 Ω / □. The transparent conductive layer can be obtained by a known film formation method depending on the material to be molded.

In addition, the transparent conductive layer can be covered with a translucent covering as necessary in order to protect it from the outside. Examples of the translucent covering include resin sheets such as fluororesin, polyvinyl chloride, and polyimide; inorganic sheets such as white plate glass and soda glass; and hybrid sheets formed by combining these materials. The thickness of these translucent coverings is not particularly limited, and it is usually preferable to adjust the resistance to be 5 to 15Ω / □.

Electron Transport Layer The electron transport layer is formed to increase the active surface area of the perovskite layer (light absorption layer), improve photoelectric conversion efficiency, and facilitate electron collection. The electron transport layer is preferably formed on the substrate. The substrate may be provided with a cathode interface layer, and an electron transport layer may be provided on the cathode interface layer. For example, the cathode interface layer may be formed by coating polyethyleneimine ethoxylate (PEIE) or polyethyleneimine (PEI) by spin coating or the like. Although the method for manufacturing the electron transport layer will be described later, the electron transport layer is preferably a flat layer using an organic semiconductor material such as a fullerene derivative, except for those described later, but the method for manufacturing the electron transport layer will be described later. Detailed description. The electron transport layer of the present invention may also serve as a (hole) blocking layer. That is, the electron transport layer of the present invention may have a function of improving the solar cell characteristics (particularly photoelectric conversion efficiency) by preventing hole leakage and suppressing reverse current.

Perovskite layer (light absorption layer)
The perovskite layer (light absorption layer) in the perovskite solar cell is a layer that performs photoelectric conversion by absorbing light and moving excited electrons. The perovskite layer (light absorption layer) contains a perovskite material or a perovskite complex. Examples of perovskite materials are CH ₃ NH ₃ PbI ₃ and complexes of this compound with ligands, and various perovskite materials and complexes described in International Publication WO2017-104792. The perovskite layer preferably achieves mass production by roll-to-roll. The mixed solution is preferably applied onto the substrate by spin coating, dip coating, screen printing, roll coating, die coating, transfer printing, spraying, slit coating, or the like, preferably by spin coating.

  The substrate is not particularly limited as long as it can support a film to be formed. The material of the substrate is not particularly limited as long as it does not impair the object of the present invention, and may be a known substrate, and any of organic compounds and inorganic compounds can be adopted. For example, any of an insulator substrate, a semiconductor substrate, a metal substrate, and a conductive substrate (including a conductive film) can be adopted. In addition, a substrate in which at least one of a metal film, a semiconductor film, a conductive film, and an insulating film is formed on part or all of these surfaces can also be suitably used.

Examples of the constituent metal of the metal film include one selected from gallium, iron, indium, aluminum, vanadium, titanium, chromium, rhodium, nickel, cobalt, zinc, magnesium, calcium, silicon, yttrium, strontium, and barium. Two or more kinds of metals are exemplified. As a constituent material of the semiconductor film, for example, elemental elements such as silicon and germanium, compounds having elements of Group 3 to Group 5, Group 13 to Group 15 of the periodic table, metal oxides, metal sulfides, Examples thereof include metal selenides and metal nitrides. Examples of the constituent material of the conductive film include tin-doped indium oxide (ITO), fluorine-doped indium oxide (FTO), zinc oxide (ZnO), aluminum-doped zinc oxide (AZO), and gallium-doped zinc oxide (GZO). , Tin oxide (SnO ₂ ), indium oxide (In ₂ O ₃ ), tungsten oxide (WO ₃ ), and the like. Examples of the constituent material of the insulating film include aluminum oxide (Al ₂ O 3), titanium oxide (TiO ₂ ), silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), and silicon oxynitride (Si ₄ O). ₅ N ₃ ) and the like, and an insulating film made of an insulating oxide is preferable, and a titanium oxide film is more preferable. In the present invention, a conductive film made of conductive oxide or insulating oxide is preferable, and tin-doped indium oxide (ITO) film, fluorine-doped indium oxide (FTO), titanium oxide (TiO ₂ ), and the like are more preferable.

  The shape of the substrate may be any shape and is effective for all shapes, for example, a plate shape such as a flat plate or a disc, a fiber shape, a rod shape, a columnar shape, a prismatic shape, Examples thereof include a cylindrical shape, a spiral shape, a spherical shape, and a ring shape, and a porous structure can also be adopted. In the present invention, a plate-like substrate is preferable. The thickness of the substrate is not particularly limited in the present invention, and is preferably 0.1 μm to 100 mm, more preferably 1 μm to 10 mm. When the substrate is a glass substrate, examples of the thickness of the substrate are 0.1 mm or more and 1 cm or less, 0.5 mm or more and 3 mm or less, or 0.5 mm or more and 2 mm or less. In addition, when the substrate is a resin substrate such as a PET substrate or a biaxially stretched polyethylene 2,6-naphthalate (PEN) substrate, an example of the thickness of the substrate is 1 μm to 200 μm, and may be 5 μm to 100 μm. However, it may be 10 μm or more and 100 μm or less.

  The perovskite layer may be a perovskite material obtained from the complex of the present invention or a layer composed only of the perovskite material of the present invention, and from the viewpoint of adhesion to the electron transport layer, a metal oxide such as meso titanium oxide or aluminum oxide. And a layer containing a perovskite material.

  The thickness of the perovskite layer (light absorption layer) is, for example, preferably 50 to 1000 nm, more preferably 200 to 800 nm, from the viewpoint of the balance between the light absorption efficiency and the exciton diffusion length and the light absorption efficiency reflected by the transparent electrode. preferable. The film thickness of the perovskite layer (light absorption layer) of the present invention is preferably in the range of 100 to 1000 nm, and more preferably in the range of 250 to 500 nm. Specifically, the lower limit of the film thickness of the perovskite layer (light absorption layer) of the present invention is preferably 100 nm or more (particularly 250 nm) or more, and the upper limit is preferably 1000 nm or less (particularly 500 nm or less). The film thickness of the perovskite layer (light absorption layer) of the present invention is measured by a cross-sectional scanning electron microscope (cross-section SEM) of the film made of the complex of the present invention.

  The flatness of the perovskite layer (light absorption layer) of the present invention is preferably 50 nm or less (−25 nm to +25 nm) in the height difference in the horizontal direction of the surface of 500 nm × 500 nm measured by a scanning electron microscope. Is more preferably 40 nm or less (-20 nm to +20 nm). This makes it easier to balance the light absorption efficiency and the exciton diffusion length, and the absorption efficiency of light reflected by the transparent electrode can be further improved. The flatness of the perovskite layer (light-absorbing layer) is the difference between the measurement point determined arbitrarily and the maximum thickness within the measurement range. The lower limit value is measured by a cross-sectional scanning electron microscope (cross-sectional SEM) of the perovskite layer (light absorption layer) of the present invention.

Hole transport layer The hole transport layer is a layer having a function of transporting charges. For the hole transport layer, for example, a conductor, a semiconductor, an organic hole transport material, or the like can be used. The material can function as a hole transport material that receives holes from the perovskite layer (light absorption layer) and transports the holes. The hole transport layer is formed on the perovskite layer (light absorption layer). Examples of the conductor and semiconductor include compound semiconductors containing monovalent copper such as CuI, CuInSe ₂ and CuS; other than copper such as GaP, NiO, CoO, FeO, Bi ₂ O ₃ , MoO ₂ and Cr ₂ O ₃ The compound containing these metals is mentioned. Among these, from the viewpoint of more efficiently receiving only holes and obtaining higher hole mobility, a semiconductor containing monovalent copper is preferable, and CuI is more preferable. Examples of the organic hole transport material include polythiophene derivatives such as poly-3-hexylthiophene (P3HT) and polyethylenedioxythiophene (PEDOT); 2,2 ′, 7,7′-tetrakis- (N, N-hour) Fluorene derivatives such as -p-methoxyphenylamine) -9,9'-spirobifluorene (spiro-OMeTAD); carbazole derivatives such as polyvinylcarbazole; poly [bis (4-phenyl) (2,4,6-trimethylphenyl) ) Amine] (PTAA) and the like; diphenylamine derivatives; polysilane derivatives; polyaniline derivatives and the like. Among these, from the viewpoint of more efficiently receiving only holes and obtaining higher hole mobility, triphenylamine derivatives, fluorene derivatives, and the like are preferable, and PTAA, spiro-OMeTAD, and the like are more preferable.

In the hole transport layer, lithium bis (trifluoromethylsulfonyl) imide (LiTFSI), silver bis (trifluoromethylsulfonyl) imide, trifluoromethylsulfonyloxysilver is used for the purpose of further improving the hole transport characteristics. , NOSbF ₆ , SbCl ₅ , SbF _5, etc. can also be included. The hole transport layer can also contain a basic compound such as t-butylpyridine (TBP), 2-picoline, 2,6-lutidine. Content of an oxidizing agent and a basic compound can be made into the quantity normally used conventionally. The thickness of the hole transport layer is, for example, preferably 30 to 200 nm, more preferably 50 to 100 nm, from the viewpoint of more efficiently receiving only holes and obtaining higher hole mobility. The method for forming the hole transport layer is preferably performed, for example, in a dry atmosphere. For example, a solution containing an organic hole transporting material is preferably applied (spin coat etc.) on a perovskite layer (light absorption layer) in a dry atmosphere and heated at 30 to 150 ° C. (especially 50 to 100 ° C.). .

Metal electrode The metal electrode is arranged to face the transparent electrode and is formed on the hole transport layer, so that charges can be exchanged with the hole transport layer. As the metal electrode, a known material used in the industry can be used, and examples thereof include metals such as platinum, titanium, stainless steel, aluminum, gold, silver, nickel, and alloys thereof. Among these, the metal electrode is preferably a material that can be formed by a method such as vapor deposition because the electrode can be formed in a dry atmosphere. A perovskite solar cell having a configuration other than the above layer configuration can also be manufactured by the same method.

Organic electroluminescence device (organic EL device)
The organic EL element is a known element as described in, for example, Japanese Patent Application Laid-Open No. 2017-123352 and Japanese Patent Application Laid-Open No. 2015-071619, and its manufacturing method is also known. An example of the organic EL element includes a substrate, an anode, a cathode, and an organic layer disposed between the anode and the cathode. The organic layer is formed by laminating a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer in this order from the anode side. The compound of the present invention can be used as an electron transport material in an electron transport layer.

Next, the manufacturing method of an electron carrying layer is demonstrated.
This method includes a solution coating step and a substituent removal step.
The solution application step is a step of applying a solution containing a benzoisoquinoline derivative represented by the formula (I ′) to a substrate to form a coating film.
The substituent removal step is a step for modifying the compound represented by the formula (I ′) after the solution coating step into a benzoisoquinoline derivative represented by the formula (I).

  The compound represented by the formula (I) has poor solubility in an organic solvent. For this reason, the compound represented by the formula (I) was not used as an electron transport material. On the other hand, in the method for producing an electron transport layer of the present invention, not the compound represented by the formula (I) but the compound represented by the formula (I ′) is contained in the coating solution. In a subsequent substituent removal step, the predetermined substituent is removed, and the compound represented by the formula (I ′) is converted into a compound represented by the formula (I). In this way, an electron transport layer containing a compound represented by the formula (I), which was not conventionally used, could be produced. When an electron transport layer containing the compound represented by the formula (I) was actually produced, it was excellent in transparency and electron transport ability. This is because in the electron transport layer containing the compound represented by the formula (I), the compound represented by the formula (I) is oriented parallel to the substrate (the inclination with respect to the substrate is not large).

  In the formula (I) and the formula (I ′), each group is as described above. Instead of the compound represented by the formula (I ′), a compound represented by the formula (II ′) or the formula (III ′) may be used. In this case, the compound is substituted with the compound represented by formula (II) or formula (III), respectively.

Examples of PG ¹ and PG ² are tert-butoxycarbonyl group (Boc), 2,2,2-trichloroethoxycarbonyl group, methoxycarbonyl group, alkoxycarbonyl group such as ethoxycarbonyl group; benzyloxycarbonyl group, paramethoxybenzyl Arylmethoxycarbonyl groups such as oxycarbonyl group and para (or ortho) nitrobenzyloxycarbonyl group; arylmethyl groups such as benzyl group, 4-methoxybenzyl group and triphenylmethyl group; alkanoyl groups such as formyl group and acetyl group; An aroyl group such as a benzoyl group; or an arylsulfonyl group such as a 2,4-dinitrobenzenesulfonyl group or an orthonitrobenzenesulfonyl group. When PG ¹ and PG ² are a tert-butoxycarbonyl group (Boc), the tert-butoxycarbonyl group is removed in the substituent removal step, and then decomposed into carbon dioxide and isobutene and volatilized from the coating film. For this reason, a tert-butoxycarbonyl group (Boc) is preferable among PG ¹ and PG ² .

Benzoisoquinoline derivative represented by the formula (I ′) The benzoisoquinoline derivative represented by the formula (I) is a known substance. This benzoisoquinoline derivative (the compound of the present invention) has an imide group. The imide group is a group that exists in a large amount in a living body, and there are many documents on a protecting group that protects the imide group and a method for removing the protecting group. Also in this specification, for example, the benzoisoquinoline derivative represented by the formula (I ′) can be obtained by appropriately using a method for introducing a protecting group into an imide group. For example, the compound of the present invention is reacted with a compound having a protecting group in a polar solvent to replace a hydrogen atom in the imide group with the protecting group.

Solution containing the benzoisoquinoline derivative represented by the formula (I ′) The solution containing the benzoisoquinoline derivative represented by the formula (I ′) contains the benzoisoquinoline derivative represented by the formula (I ′) in an amount of 0. 1 g or more and 500 g or less may be included, 1 g or more and 100 g or less may be included, and 3 g or more and 20 g or less may be included. This solution preferably contains an organic solvent as the first solvent. Examples of the organic solvent are amide solvents, aromatic organic solvents, glycol ethers, and glycol esters. Examples of specific organic solvents are N, N-dimethylacetamide, N, N-dimethylformamide, N-methylpyrrolidone, toluene, xylene, ethylbenzene, chlorobenzene, orthodichlorobenzene, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, Propylene glycol monomethyl ether, 3-methoxy-3-methyl-1-butanol, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate. Although the said organic solvent can also be used independently, it can also be mixed and used for arbitrary ratios, Furthermore, it can also be used in combination with another organic solvent.

  The organic solvent may be the first organic solvent, may be used in combination with the first organic solvent and the second organic solvent, or the second organic solvent described below may be used. Examples of the second organic solvent are alcohols such as methanol, ethanol and isopropanol, glycols such as ethylene glycol and diethylene glycol, ketones such as acetone and methyl ethyl ketone, and halogenated carbons such as dichloromethane, chloroform and carbon tetrachloride. . The second organic solvent can also be used alone, but can also be used by mixing at an arbitrary ratio. The weight ratio of the first organic solvent and the second organic solvent is arbitrary, and an example of the weight ratio is 1: 100 or more and 100: 1 or less, and may be 1:10 or more and 10: 1 or less. : 5 or more and 5: 1 or less may be sufficient.

  The electron transport layer obtained using this solution may contain an organic substance derived from an organic solvent in addition to the compound of the present invention.

Examples of application methods for applying the solution are screen printing, dip coating, spin coating, roller coating, and spray coating. Of these, spin coating or roller coating is preferred. In addition, application | coating can be performed at about 15-30 degreeC, for example.

  The thickness of the electron transport layer is not particularly limited, and is preferably about 10 to 300 nm, more preferably about 10 to 250 nm, from the viewpoint of collecting more electrons from the perovskite layer (light absorption layer). On the other hand, since the compound of the present invention has high electron transport ability, the thickness of the electron transport layer may be 3 nm to 9 nm, 4 nm or more and 8 nm or less, or 4 nm or more and 7 nm or less.

Substituent Removal Step The substituent removal step is basically performed by annealing (annealing) or the like, and the substituents (PG ¹ and PG ² ) bonded to the imide group in the benzoisoquinoline derivative represented by the formula (I ′). ) Is removed. In the substituent removal step, an annealing treatment may be performed in which the coating film is maintained at 100 ° C. or higher and 200 ° C. or lower for 5 minutes or longer and 1 day or shorter. The annealing temperature may be 145 ° C. or higher and 200 ° C. or lower, 150 ° C. or higher and 200 ° C. or lower, 160 ° C. or higher and 195 ° C. or lower, or 170 ° C. or higher and 190 ° C. or lower. The annealing treatment time may be 20 minutes or more and 5 hours or less, 20 minutes or more and 3 hours or less, or 30 minutes or more and 2 hours or less.

  The substituent removal step may include an acid contact step in which an acid is brought into contact with the coating film and a step (annealing step) of bringing the coating film to 150 ° C. or more and 200 ° C. or less. The acid contact step and the annealing step may be performed simultaneously, or one of them may be performed first. Examples of acids used in the acid contacting step are hydrochloric acid, sulfuric acid, acetic acid or nitric acid. These acids can be applied to the coating film with a sprayer in a diluted state (for example, 0.01 M or more and 0.5 M or less, 0.1 M or more and 0.5 M or less). What is necessary is just to contact. This facilitates substituent removal. What is necessary is just to adjust the spraying amount of an acid suitably.

In the substituent removal step, a method of irradiating the coating film with ultraviolet rays, visible light, infrared rays, X-rays or neutrons according to the substituents (PG ¹ and PG ² ) or the compound of the present invention may be employed. .

  The present invention also provides a method for manufacturing a solar cell. This method includes the steps of forming an electron transport layer on a substrate, forming a light absorption layer on the electron transport layer, and forming holes on the light absorption layer using the method for manufacturing an electron transport layer described above. A step of forming a transport layer and a step of forming an electrode on the hole transport layer.

  Hereinafter, the present invention will be specifically described with reference to examples. The present invention is not limited to the following examples. The scope of the present invention includes inventions that those skilled in the art can apply and extend known techniques based on the following embodiments.

[Introduction of Boc group]

  Naphthalenediimide 1 (1.06 g, 4.0 mmol) was suspended in dichloromethane (80 mL) and di-tert-butyl dicarbonate (2.63 g, 12.0 mmol), 4-dimethylaminopyridine ( 98 mg, 0.8 mmol) was added. After stirring at room temperature for 8 hours, water (100 mL) was added, and the mixture was extracted 3 times with dichloromethane (50 mL). The combined organic layers were dried over sodium sulfate, filtered and concentrated to obtain a crude product. Purification by silica gel column chromatography using dichloromethane as a developing solvent and recrystallization from dichloromethane / hexane gave Boc-protected naphthalenediimide 2 (1.23 g, 66%).

  Shimadzu Corporation TGA-50 was used for thermogravimetry. 5.32 mg of Boc-protected naphthalene diimide 2 was weighed and the change in weight was measured while heating at a rate of 2 ° C./min in a nitrogen atmosphere. The result is shown in FIG. FIG. 1 is a graph instead of a drawing showing the results of thermogravimetry in the examples. A decrease in weight of 42.7% was observed with respect to the raw material at around 170 ° C to 190 ° C. This corresponds to the weight of the two Boc groups (calculated value 42.9%), and the removal of the Boc groups by heating. Suggests separation.

  Shimadzu UV-3150 was used for UV-visible absorption measurement. Boc-protected naphthalenediimide 2 was dissolved in chlorobenzene (7 mg / mL), and a thin film was formed by spin-coating on a quartz substrate at 1000 rpm for 60 seconds. An attempt was made to deprotect the Boc group on the substrate by annealing this sample at 180 ° C. for 1 hour. FIG. 2 is a graph replaced with a drawing showing ultraviolet-visible absorption characteristics in the examples. The UV-visible absorption characteristics of the sample before and after annealing were measured, and the absorption spectrum was found to change with the elimination of the Boc group by annealing.

A Thermo Fisher Scientific Nicolet 6700 FT-IR spectrometer was used for polarized infrared polygonal incidence spectroscopy (pMAIRS) measurement. FIG. 3 is a graph instead of a drawing showing measurement results by polarized infrared polygonal incidence spectroscopy in the examples. The upper part of FIG. 3 shows the spectrum of Boc-protected naphthalene diimide, and the lower part of FIG. 3 shows the spectrum of naphthalene diimide. FIG. 4 shows a study on the angle between the compound and the substrate derived from the measurement result by polarized infrared polygonal incidence spectroscopy. Boc-protected naphthalene diimide 2 was dissolved in chloroform (10 mg / mL), and a thin film was formed by spin coating at 1000 rpm for 60 seconds on a silicon substrate (Valker FFT). In the sample annealed at 180 ° C. for 1 hour, it was confirmed that the Boc group was deprotected due to the disappearance of the 1771 cm ⁻¹ peak derived from the C═O stretching of the Boc group. . Further, when attention is paid to the peak of the CH out-of-plane deformation angle of the naphthalene ring observed in the vicinity of 880 cm ⁻¹ , the absorbance in the in-plane direction and the absorbance in the out-of-plane direction are the same before annealing, but after annealing. Shows that the absorbance in the out-of-plane direction is significantly higher. Considering that the dipole moment change is perpendicular to the π plane at the CH out-of-plane deflection angle, this result indicates that the naphthalenediimide molecules are oriented face-on (parallel) to the substrate. It suggests. Actually, as a result of calculating the orientation angle Φ according to the relational expression Φ = tan ⁻¹ {(2A _IP / A _OP ) ^1/2 } using the absorbance A _{IP in} the in-plane direction and the absorbance A _OP in the out-of-plane direction, annealing was performed. It was found that the orientation angle changed from 56 degrees to 29 degrees before and after. The orientation of the face-on obtained in the annealed film is considered to be advantageous for charge transport in the direction perpendicular to the substrate.

Production of Perovskite Solar Cell FIG. 5 is a conceptual diagram showing the configuration of the solar cell in the example. In this example, a solar cell having the structure shown in FIG. 5 was manufactured.

A glass substrate with ITO (25 mm × 24 mm, Geomatic) was ultrasonically cleaned in the order of water, acetone, semicoclean 56, water, and ethanol for 15 minutes. Finally, UV ozone cleaning for 15 minutes was performed.
The ITO substrate was spin-coated with a 2-methoxyethanol solution of 0.1 wt% polyethyleneimine ethoxylate (PEIE) as a cathode interface layer at 4000 rpm for 60 seconds, and annealed at 100 ° C. for 10 minutes. Next, a 10 mg / mL chloroform solution of Boc-protected naphthalenediimide 2 (10% polymethyl methacrylate added to reduce crystallinity) was spin-coated at 1000 rpm for 60 seconds as an electron transport layer. The Boc group was deprotected by annealing the substrate at 180 ° C. for 1 hour.

To a mixture containing PbI ₂ and MAI at a 1: 1 (molar ratio), a mixed solvent of DMF and DMSO (volume ratio 3: 1) was added to a concentration of 1.5M. This solution was spin-coated, and 450 μL of toluene was dropped along the way. The obtained film was annealed at 100 ° C. to produce a perovskite layer.

Hole transport material (Spiro-OMeTAD; 2,2 ′, 7,7′-tetrakis (N, N-di-p-methoxyphenylamine) -9,9′-spirobifluorene, 73.6 mg), [ Tris (2- (1H-pyrazol-1-yl) -4-tert-butylpyridine) cobalt (III) tris (bis (trifluoromethylsulfonyl) imide)] (FK209, 13.3 mg), 4-tert- Butylpyridine (TBP, 27 μL) and lithium bis (trifluoromethylsulfonyl) imide (LiTFSI, 7.6 mg) were dissolved in 1 mL of chlorobenzene. After stirring for 30 minutes, the solution was filtered through a membrane filter, and the filtrate was spin-coated on a perovskite layer at 4000 rpm for 30 seconds and annealed at 70 ° C. for 30 minutes. Finally, a gold electrode of 80 nm was attached by vacuum evaporation to obtain a perovskite solar cell.
In the obtained perovskite solar cell, current density-voltage characteristics were measured. The result is shown in FIG. FIG. 6 is a graph instead of a drawing showing the current density-voltage characteristics of the perovskite solar cells obtained in the examples. As shown in FIG. 6, the short circuit current density J _SC = 14.5 mA cm ⁻² , the open circuit voltage V _OC = 0.87 V, the fill factor FF = 0.42, and the photoelectric conversion efficiency (PCE) is 6. 2%. From the above, it was found that the naphthalene diimide 1 film prepared by thermal conversion of Boc-protected naphthalene diimide 2 functions as an electron transport layer.

  The present invention can be used not only in the information electronics industry such as solar cells and organic EL, but also in the chemical industry that provides electron transport materials.

Claims (8)

An electron transport layer comprising a benzoisoquinoline derivative represented by the formula (I).

(In the formula (I), X ¹ and X ² may be the same or different and represent O, S, Se or Te,
Y ¹ is a hydrogen atom, a methyl group, a fluorine atom, or a chlorine atom,
R ^{1 to} R ⁴ may be the same or different and are a hydrogen atom, a C _{1 to} C ₆ alkyl group, a C _{1 to} C ₆ alkoxy group, a cyano group, a nitro group, a fluorine atom, or a chlorine atom,
R ¹ and R ² and R ³ and R ⁴ may be substituted with a halogen atom, a C _{1 to} C ₆ alkyl group, or a C _{1 to} C ₆ alkoxy group together with the bonded atoms. C ₃ -C ₁₂ cycloalkyl group, C ₆ -C ₁₄ aryl group, C ₈ -C ₁₄ aralkyl group, C ₃ -C ₁₂ heterocycloalkyl group, C ₆ -C ₁₄ heteroaryl group, C ₃ -C ₁₂ heterocycloalkyl group, C ₆ -C ₁₄ heteroaryl group, C ₈ -C ₁₄ heteroaralkyl group or C ₃ -C ₁₄ heterocyclyl group,
R ¹¹ and R ^{12, which} may be the same or different, are a hydrogen atom, a methyl group, a methoxy group, a cyano group, a nitro group, a fluorine atom, or a chlorine atom, or bonded atoms and those atoms, respectively. Together with the intervening atoms, it constitutes any group selected from group A below. )

Group A

(In the formulas (Ia) to (Im),
X ³ and X ⁴ may be the same or different and represent O, S, Se or Te;
X ¹¹ represents O or S,
Y ² is a hydrogen atom, a methyl group, a fluorine atom, or a chlorine atom,
R ¹³ and R ¹⁴ may be the same or different and are a hydrogen atom, a methyl group, a methoxy group, a cyano group, a nitro group, a fluorine atom, or a chlorine atom. )
The electron transport layer according to claim 1,
An electron transport layer, wherein the benzoisoquinoline derivative represented by the formula (I) is a naphthalenediimide derivative represented by the formula (II).

(In formula (II), X ^{1 to} X ⁴ may be the same or different and each represents O, S, Se or Te;
Y ¹ and Y ² may be the same or different and are a hydrogen atom, a methyl group, a fluorine atom, or a chlorine atom,
R ^{1 to} R ⁴ may be the same or different and are a hydrogen atom, a methyl group, a methoxy group, a cyano group, a nitro group, a fluorine atom, or a chlorine atom,
R ¹ and R ² and R ³ and R ⁴ may be substituted with a halogen atom, a C _{1 to} C ₆ alkyl group, or a C _{1 to} C ₆ alkoxy group together with the bonded atoms. C ₃ -C ₁₂ cycloalkyl group, C ₆ -C ₁₄ aryl group, C ₈ -C ₁₄ aralkyl group, C ₃ -C ₁₂ heterocycloalkyl group, C ₆ -C ₁₄ heteroaryl group, C ₃ -C ₁₂ heterocycloalkyl _group, C 6 _{-C 14} heteroaryl _group, a C 8 _{-C 14} heteroaralkyl group, or _C 3 _{-C 14} heterocyclyl group. )
The electron transport layer according to claim 1,
An electron transport layer, wherein the benzoisoquinoline derivative represented by the formula (I) is a compound represented by the formula (III).

  A solar cell comprising the electron transport layer according to claim 3.   An organic electroluminescence device comprising the electron transport layer according to claim 3. A method for manufacturing an electron transport layer, comprising:
Applying a solution containing a benzoisoquinoline derivative represented by formula (I ′) to a substrate to form a coating film; and
A substituent removal step for modifying the benzoisoquinoline derivative represented by the formula (I ′) after the solution coating step into a benzoisoquinoline derivative represented by the formula (I);
The manufacturing method of the electron carrying layer containing this.

(In Formula (I) and Formula (I ′), X ¹ and X ² may be the same or different and each represents O, S, Se, or Te,
Y ¹ is a hydrogen atom, a methyl group, a fluorine atom, or a chlorine atom,
R ¹ to R ^4, which may be the same or different, a hydrogen _atom, C 1 -C ₆ alkyl _group, C 1 -C6 alkoxy group, a cyano group, a nitro group, a fluorine atom, or a chlorine atom,
R ¹ and R ² and R ³ and R ⁴ may be substituted with a halogen atom, a C _{1 to} C ₆ alkyl group, or a C _{1 to} C ₆ alkoxy group together with the bonded atoms. A 3-10 membered cyclyl group, a 5-10 membered aryl group, a 3-10 membered heterocyclyl group or a 5-10 membered heteroaryl group,
R ¹¹ and R ^{12, which} may be the same or different, are a hydrogen atom, a methyl group, a methoxy group, a cyano group, a nitro group, a fluorine atom, or a chlorine atom, or bonded atoms and those atoms, respectively. Together with the atoms in between form any group selected from group A below,
PG ¹ represents tert-butoxycarbonyl group, 2,2,2-trichloroethoxycarbonyl group, methoxycarbonyl group, ethoxycarbonyl group; benzyloxycarbonyl group, paramethoxybenzyloxycarbonyl group, para (or ortho) nitrobenzyloxycarbonyl Group: benzyl group, 4-methoxybenzyl group, triphenylmethyl group; formyl group, acetyl group; benzoyl group; 2,4-dinitrobenzenesulfonyl group, or orthonitrobenzenesulfonyl group. )

Group A

(In the formulas (Ia) to (Im),
X ³ and X ⁴ may be the same or different and represent O, S, Se or Te;
X ¹¹ represents O or S,
Y ² is a hydrogen atom, a methyl group, a fluorine atom, or a chlorine atom,
R ¹³ and R ¹⁴ may be the same or different and are a hydrogen atom, a methyl group, a methoxy group, a cyano group, a nitro group, a fluorine atom, or a chlorine atom. ) It is a manufacturing method of the electron carrying layer of Claim 6, Comprising:
The said substituent removal process is a manufacturing method of an electron carrying layer including the acid contact process which makes an acid contact the said coating film, and the process which makes the said coating film 100 degreeC or more and 200 degrees C or less. A solar cell manufacturing method comprising:
Forming the electron transport layer on the substrate using the method for producing an electron transport layer according to claim 6;
Forming a light absorption layer on the electron transport layer;
Forming a hole transport layer on the light absorbing layer;
Forming an electrode on the hole transport layer,
A method for manufacturing a solar cell.

Images