Light-emitting materials and light-emitting devices

Abstract

To provide a light-emitting material that includes semiconductor nanoparticles and has excellent stability.SOLUTION: A light-emitting material includes semiconductor nanoparticles including first semiconductors, which include group 11 elements including Ag and optionally including Cu, group 13 elements including at least one of In and Ga, and group 16 elements including Sa. The semiconductor nanoparticles have their surfaces having second semiconductors including at least Ga and S disposed thereon, and the second semiconductors have their surfaces having diamine compounds disposed thereon.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This disclosure relates to light-emitting materials and light-emitting devices. [Background technology]

[0002] It is known that when semiconductor particles have a particle size of, for example, 10 nm or less, the quantum size effect occurs, and such nanoparticles are called quantum dots (also called semiconductor quantum dots). The quantum size effect refers to the phenomenon in which the valence band and conduction band, which are considered continuous in bulk particles, become discrete when the particle size is nanoscale, and the band gap energy changes depending on the particle size.

[0003] Because quantum dots can absorb light and convert its wavelength to light corresponding to its bandgap energy, white light-emitting devices utilizing wavelength-converting components containing quantum dots have been proposed. To improve the luminescence efficiency of quantum dots, a technique is known in which organic ligands are bonded to the surface of quantum dots. For example, Patent Document 1 proposes a quantum dot having a molecule containing both a bonding group to the quantum dot and a hydrophilic group in its outer layer. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Special Publication No. 2002-525394 [Overview of the project] [Problems that the invention aims to solve]

[0005] When preparing wavelength conversion components containing quantum dots, cleaning the quantum dots sometimes reduced the quantum emission efficiency. One aspect of this disclosure aims to provide a light-emitting material containing semiconductor nanoparticles that exhibits excellent stability. [Means for solving the problem]

[0006] The first aspect is a light-emitting material including semiconductor nanoparticles including a first semiconductor including a Group 11 element that may contain Ag and may contain Cu, a Group 13 element including at least one of In and Ga, and a Group 16 element including S. On the surface of the semiconductor nanoparticles, a second semiconductor including at least Ga and S is disposed, and on the surface of the second semiconductor, a diamine compound is disposed to constitute the light-emitting material.

[0007] The second aspect is a light-emitting device including a wavelength conversion member including the light-emitting material of the first aspect and a light-emitting element.

Advantages of the Invention

[0008] According to one aspect of the present disclosure, a light-emitting material including semiconductor nanoparticles and having excellent stability can be provided.

Brief Description of the Drawings

[0009] [[ID=!17]] [Figure 1] It is a schematic cross-sectional view showing an example of the light-emitting device.

Embodiments for Carrying Out the Invention

[0010] In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, as long as their intended purpose is achieved. Furthermore, the content of each component in a composition refers to the total amount of multiple substances present in the composition, unless otherwise specified, if multiple substances corresponding to each component exist in the composition. In addition, the upper and lower limits of the numerical ranges described herein can be arbitrarily selected and combined from the numerical values ​​exemplified as numerical ranges. In this specification, in formulas representing the composition of a phosphor or luminescent material, multiple elements separated by commas (,) mean that at least one of these multiple elements is contained in the composition. Also, in formulas representing the composition of a phosphor, the element before the colon (:) represents the matrix crystal, and the element after the colon (:) represents the activating element. In this specification, the relationship between color names and chromaticity coordinates, the relationship between the wavelength range of light and the color names of monochromatic light, etc., follow JIS Z8110. The full width at half maximum (FWHM) of a phosphor refers to the wavelength width (FWHM) of the emission spectrum where the emission intensity is 50% of the maximum emission intensity. Embodiments of the present invention will be described in detail below. However, the embodiments shown below are illustrative of semiconductor nanoparticles and light-emitting devices for realizing the technical concept of the present invention, and the present invention is not limited to the semiconductor nanoparticles and light-emitting devices shown below. In addition, the size, positional relationships, etc. of the components shown in the drawings may be exaggerated for clarity of explanation.

[0011] Luminescent materials The light-emitting material is composed of semiconductor nanoparticles and a diamine compound. The semiconductor nanoparticles include a first semiconductor comprising at least one Group 11 element which may include silver (Ag) and copper (Cu), at least one of Group 13 elements which may include at least one of indium (In) and gallium (Ga), and at least one of Group 16 elements which may include sulfur (S), and a second semiconductor which comprises at least Ga and S. The second semiconductor is arranged on the surface of the semiconductor nanoparticles, and the diamine compound is arranged on the surface of the second semiconductor to constitute the light-emitting material.

[0012] In light-emitting materials containing semiconductor nanoparticles with a diamine compound on their surface, stability is improved. This suppresses, for example, the decrease in luminescence quantum efficiency due to cleaning treatment. This is thought to be because the bond between the diamine compound and the semiconductor nanoparticles is more stable compared to other ligands.

[0013] The semiconductor nanoparticles constituting the light-emitting material exhibit band-edge emission, having an emission peak wavelength in a wavelength range longer than the wavelength of the irradiated light, upon irradiation with light. Furthermore, the semiconductor nanoparticles exhibit high band-edge emission purity and high internal quantum efficiency of band-edge emission. This can be attributed, for example, to the fact that the crystal structure of the first semiconductor located in the center of the semiconductor nanoparticle is substantially tetragonal (chalcopyrite structure), and the second semiconductor arranged on the surface of the semiconductor nanoparticle has a crystal structure with few Ga defects (e.g., areas where Ga is deficient). The second semiconductor may be a semiconductor with a higher Ga composition ratio than the first semiconductor, or a semiconductor with a lower Ag composition ratio than the first semiconductor, and may be a semiconductor substantially composed of Ga and S. In addition, in the semiconductor nanoparticles, an adsorbent containing the second semiconductor may be arranged on the surface of the particle containing the first semiconductor, and the adsorbent containing the second semiconductor may cover the particle containing the first semiconductor. Furthermore, the semiconductor nanoparticles may have a core-shell structure in which, for example, a particle containing the first semiconductor serves as the core, and an adsorbent containing the second semiconductor serves as the shell, with the shell arranged on the surface of the core. Furthermore, the second semiconductor arranged on the surface of the semiconductor nanoparticles may have a uniform composition or a composition that varies in the thickness direction.

[0014] First Semiconductor The first semiconductor constituting the semiconductor nanoparticles comprises at least one Group 11 element containing Ag and possibly Cu, at least one Group 13 element containing at least one of In and Ga, and at least one Group 16 element containing S. Generally, semiconductors containing Ag, In, and S, and having a tetragonal, hexagonal, or orthorhombic crystal structure, are known to be represented by the empirical formula AgInS2. The first semiconductor may have a composition represented by (Ag,Cu)(In,Ga)S2, in which some of the Ag is substituted with Cu and some of the In is substituted with Ga. On the other hand, in reality, the composition is not stoichiometric, and in particular, the ratio of the number of Ag and Cu atoms to the number of In and Ga atoms ((Ag+Cu) / (In+Ga)) may be less than 1, or conversely, greater than 1. Also, the sum of the number of Ag and Cu atoms and the number of In and Ga atoms may not be the same as the number of S atoms. Therefore, in this specification, when a semiconductor containing a specific element is not considered to have a stoichiometric composition, the semiconductor composition may be expressed using an expression in which the constituent elements are connected by a hyphen, such as Cu-Ag-In-Ga-S. Thus, the composition of the first semiconductor according to this embodiment can be considered as Cu-Ag-In-Ga-S or Cu-Ag-Ga-S, where, for example, a part of the Ag-In-S composition is replaced with Cu, which is also a group 11 element, and a part or all of the In, which is a group 13 element, is replaced with Ga, which is also a group 13 element.

[0015] Furthermore, the first semiconductor containing the aforementioned elements and having a hexagonal crystal structure is of the wurtzite type, while the semiconductor having a tetragonal crystal structure is of the chalcopyrite type. The crystal structure is identified, for example, by measuring the XRD pattern obtained by X-ray diffraction (XRD) analysis. Specifically, the XRD pattern obtained from the first semiconductor is compared with a known XRD pattern of semiconductor nanoparticles represented by the AgInS2 composition, or an XRD pattern obtained by simulation from crystal structure parameters. If there is a pattern among the known patterns and simulation patterns that matches the pattern of the first semiconductor, then the crystal structure of the semiconductor nanoparticle can be said to be the crystal structure of the matching known or simulation pattern.

[0016] In an aggregate of semiconductor nanoparticles, semiconductor nanoparticles containing a first semiconductor with different crystal structures may be mixed. In that case, peaks originating from multiple crystal structures will be observed in the XRD pattern. In one embodiment of semiconductor nanoparticles, the first semiconductor may be substantially tetragonal, and peaks corresponding to the tetragonal structure may be observed, while peaks originating from other crystal structures may not be substantially observed.

[0017] The Group 11 elements in the composition of the first semiconductor include Ag, Cu, and Au. The first semiconductor may contain substantially only Ag as a Group 11 element, or it may contain Ag and Cu. Containing substantially only Ag means that the ratio of the total number of atoms other than Ag to the total number of atoms of Group 11 elements is, for example, 10% or less, preferably 5% or less, or 1% or less.

[0018] When the first semiconductor contains Ag and Cu as Group 11 elements, the total content of Ag and Cu in the composition of the first semiconductor may be, for example, 10 mol% to 30 mol%, preferably 15 mol% to 25 mol%. The total content of In and Ga in the composition of the first semiconductor may be, for example, 15 mol% to 35 mol%, preferably 20 mol% to 30 mol%. The total content of S in the composition of the first semiconductor may be, for example, 35 mol% to 55 mol%, preferably 40 mol% to 55 mol%.

[0019] The first semiconductor may further contain at least one alkali metal by substituting some of the Group 11 elements, and may be substantially composed of Group 11 elements. Here, "substantially" means that the ratio of the total number of alkali metal atoms to the total number of Group 11 elements and alkali metals is, for example, 10% or less, preferably 5% or less, and more preferably 1% or less.

[0020] When the first semiconductor contains Ag and Cu as Group 11 elements, it can be considered that a portion of Ag is substituted for Cu in the composition of the first semiconductor. When a portion of Ag is substituted for Cu, compared to the case with Ag alone, for example, the band gap becomes narrower and the emission peak wavelength shifts to the longer wavelength side. For example, the ratio of the number of moles of Cu to the total number of moles of Cu and Ag in the composition of the first semiconductor (Cu / (Cu+Ag)) may be 0.01 or more and less than 1.0, preferably 0.03 or more and 0.99 or less, or 0.05 or more and 0.5 or less. Also, for example, the ratio of the total number of moles of Cu and Ag to the total number of moles of Cu, Ag, In and Ga in the composition of the first semiconductor ((Cu+Ag) / (Cu+Ag+In+Ga)) may be 0.1 or more and less than 1.0, preferably 0.2 or more and 0.99 or less.

[0021] Furthermore, the first semiconductor is substantially composed of Ag, Cu, and alkali metals (hereinafter referred to as M aThe constituent elements may include (sometimes written as ). Here, "substantially" means that the ratio of the total number of atoms of elements other than Ag, Cu, and alkali metals to the total number of atoms of elements other than Ag, Cu, and alkali metals is, for example, 10% or less, preferably 5% or less, and more preferably 1% or less. Alkali metals include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs). Since alkali metals can become monovalent cations like Ag, they can substitute for a portion of Ag in the composition of the first semiconductor. Li, in particular, has an ionic radius similar to that of Ag and is therefore preferably used. By substituting a portion of Ag in the composition of the first semiconductor, for example, the band gap widens and the emission peak wavelength shifts to a shorter wavelength. Although the details are unclear, it is also thought that lattice defects in the first semiconductor are reduced and the internal quantum efficiency of band-edge emission is improved. If the first semiconductor contains alkali metals, it may contain at least Li.

[0022] The first semiconductor is Ag, Cu and alkali metal (M a If it contains ), the alkali metal content in the composition of the first semiconductor may be, for example, greater than 0 mol% and less than 30 mol%, preferably 1 mol% or more and 25 mol% or less. Also, the number of Ag atoms, the number of Cu atoms and alkali metal (M) in the composition of the first semiconductor. a The ratio of the number of alkali metal (Ma) atoms to the total number of atoms of (M) a / (Ag+Cu+M a )) may be, for example, less than 1, preferably 0.8 or less, 0.4 or less, or 0.2 or less. The ratio may also be, for example, greater than 0, preferably 0.05 or more, or 0.1 or more.

[0023] The first semiconductor contains a group 13 element in its composition, which includes at least one of In and Ga. In addition to In and Ga, the group 13 elements in the composition of the first semiconductor may include Al, Tl, etc. The first semiconductor contains at least one of In and Ga, and may further contain at least one of Al and Tl by substitution of a portion thereof, and may be substantially composed of In and Ga. Here, "substantially" means that the ratio of the total number of Al and Tl atoms to the total number of In and Ga and Al and Tl atoms is, for example, 10% or less, preferably 5% or less, and more preferably 1% or less.

[0024] The ratio of the number of In atoms to the total number of In and Ga atoms in the first semiconductor (In / (In+Ga)) may be, for example, 0.01 or more and less than 1, preferably 0.1 or more and 0.99 or less. When the ratio of the number of In atoms to the total number of In and Ga atoms is within a predetermined range, a short-wavelength emission peak wavelength (for example, 545 nm or less) can be obtained. The ratio of the number of Ag atoms to the total number of In and Ga atoms (Ag / (In+Ga)) may be, for example, 0.1 or more and 1.2 or less, preferably 0.2 or more and 1.1 or less. The ratio of the total number of Ag and Cu atoms to the total number of In and Ga atoms ((Ag+Cu) / (In+Ga)) may be, for example, 0.1 or more and 1.2 or less, preferably 0.2 or more and 1.0 or less. The ratio of the number of S atoms to the total number of Ag, In, and Ga atoms (S / (Ag+In+Ga)) may be, for example, 0.8 or more and 1.5 or less, preferably 0.9 or more and 1.2 or less. The ratio of the number of S atoms to the total number of Ag, Cu, In, and Ga atoms (S / (Ag+Cu+In+Ga)) may be, for example, 0.8 or more and 1.5 or less, preferably 0.9 or more and 1.2 or less.

[0025] The first semiconductor contains a Group 16 element containing sulfur (S). As the Group 16 element in the composition of the first semiconductor, in addition to S, Se, Te, etc. are included. The first semiconductor contains S, and a part of it may be substituted to further contain at least one of the elements Se and Te, or may be substantially composed of S. Here, "substantially" means that the ratio of the total number of atoms of Se and Te to the total number of atoms of S, Se and Te is, for example, 10% or less, preferably 5% or less, more preferably 1% or less.

[0026] The first semiconductor may be substantially composed of Cu, Ag, In, Ga, S, and elements substituting a part of them described above. Here, the term "substantially" is used in consideration of the inevitable inclusion of other elements other than Cu, Ag, In, Ga, S, and elements substituting a part of them due to the mixing of impurities, etc.

[0027] The first semiconductor may have a composition represented by, for example, the following formula (1). (Ag p Cu (1-p) ) q In r Ga (1-r) S (q+3) / 2 (1) Here, p, q, and r satisfy 0 < p ≤ 1, 0.20 < q ≤ 1.2, and 0 < r < 1.

[0028] In one aspect, the first semiconductor contains Ag, In, Ga, and S, the ratio of the number of atoms of Ga to the total number of atoms of In and Ga is 0.95 or less, and may emit light having an emission peak wavelength in the range of 500 nm or more and less than 590 nm and a full width at half maximum of the emission peak of 70 nm or less upon light irradiation.

[0029] In one embodiment, the first semiconductor may have a ratio of the number of Ga atoms to the total number of Ga atoms (Ga / (Ga+In)) (hereinafter also referred to as the "Ga ratio") which is preferably 0.2 to 0.9, preferably 0.25 or more, 0.3 or more, or 0.5 or more, and also preferably 0.85 or less, 0.8 or less, or 0.75 or less. Furthermore, the ratio of the number of Ag atoms to the total number of Ag atoms to the total number of Ag atoms to In and Ga (Ag / (Ag+In+Ga)) (hereinafter also referred to as the "Ag ratio") may be 0.05 to 0.55, preferably 0.25 or more, or 0.3 or more, and also preferably 0.5 or less, or 0.3 or less. In addition, the ratio of the number of S atoms to the total number of Ag atoms to the total number of Ag atoms to In and Ga (S / (Ag+In+Ga)) may be, for example, 0.6 to 1.6.

[0030] In another embodiment, the first semiconductor comprises Ag and Cu, at least one of In and Ga, and S, wherein the ratio of the number of Cu atoms to the total number of Ag and Cu atoms is 0.001 or more and 0.9 or less, and may emit light upon irradiation with light having an emission peak wavelength in the range of 500 nm to 820 nm and an emission peak full width at half maximum of 70 nm or less.

[0031] In another embodiment, the first semiconductor may have a ratio of the number of Cu atoms to the total number of Ag and Cu atoms, preferably between 0.005 and 0.5. Furthermore, the ratio of the total number of In and Ga atoms to the total number of Ag and Cu atoms may be between 0.5 and 10, between 0.8 and 5, or between 0.9 and 2. Additionally, the ratio of S atoms to the total number of Ag and Cu atoms may be between 1 and 10, between 1.5 and 8, or between 2 and 3.

[0032] The chemical composition of the first semiconductor can be identified, for example, by X-ray fluorescence analysis (XRF).

[0033] Second Semiconductor The semiconductor nanoparticles may have a second semiconductor disposed on their surface. The second semiconductor may have a composition containing at least Ga and S. The second semiconductor may contain a semiconductor with a larger bandgap energy than the first semiconductor. The composition of the second semiconductor may have a larger molar content of Ga compared to the composition of the first semiconductor. The ratio of the molar content of Ga in the second semiconductor composition to the molar content of Ga in the first semiconductor composition may be, for example, greater than 1 and 5 or less, preferably 1.1 or more, and preferably 3 or less.

[0034] Furthermore, the composition of the second semiconductor may have a lower molar content of Ag compared to the composition of the first semiconductor. The ratio of the molar content of Ag in the second semiconductor composition to the molar content of Ag in the first semiconductor composition may be, for example, 0.1 or more and 0.7 or less, preferably 0.2 or more, and preferably 0.5 or less. The ratio of the molar content of Ag in the composition of the second semiconductor may be, for example, 0.5 or less, preferably 0.2 or less, or 0.1 or less, and may be substantially 0. Here, "substantially" means that when the total number of atoms of all elements contained in the second semiconductor is taken as 100%, the proportion of Ag atoms is, for example, 10% or less, preferably 5% or less, or 1% or less. In other words, the second semiconductor may have a composition that contains Ga and S, but substantially does not contain Ag.

[0035] In the composition of the semiconductor containing Ga and S included in the second semiconductor, a portion of Ga may be substituted with at least one Group 13 element selected from the group consisting of boron (B), aluminum (Al), indium (In), and thallium (Tl). Also, a portion of S may be substituted with at least one Group 16 element selected from the group consisting of oxygen (O), selenium (Se), tellurium (Te), and polonium (Po).

[0036] In one embodiment, the second semiconductor may be a semiconductor substantially composed of Ga and S. Here, "substantially" means that when the total number of atoms of all elements contained in the semiconductor containing Ga and S is taken as 100%, the proportion of atoms of elements other than Ga and S is, for example, 10% or less, preferably 5% or less, and more preferably 1% or less. That is, the second semiconductor may be gallium sulfide. The gallium sulfide in this specification may have a stoichiometric composition (e.g., Ga2S3), or Ga-S, or GaS x It may have the composition represented by , where x is any number not limited to an integer, for example, it may be between 0.8 and 1.5.

[0037] The second semiconductor may be constructed by selecting its composition and other properties according to the bandgap energy of the first semiconductor described above. Alternatively, if the composition and other properties of the second semiconductor have been determined in advance, the first semiconductor may be designed so that its bandgap energy is smaller than that of a semiconductor containing Ga and S. Generally, a semiconductor made of Ag-In-S has a bandgap energy of 1.8 eV to 1.9 eV.

[0038] Specifically, the second semiconductor may have a bandgap energy of, for example, 2.0 eV to 5.0 eV, and more particularly 2.5 eV to 5.0 eV. Furthermore, the bandgap energy of the second semiconductor may be larger than that of the first semiconductor by, for example, approximately 0.1 eV to 3.0 eV, more particularly approximately 0.3 eV to 3.0 eV, and more particularly approximately 0.5 eV to 1.0 eV. When the difference between the bandgap energy of the second semiconductor and the bandgap energy of the first semiconductor is greater than or equal to the aforementioned lower limit, the proportion of emission other than band-edge emission from the semiconductor nanoparticles tends to decrease, while the proportion of band-edge emission tends to increase.

[0039] The second semiconductor may contain oxygen (O) atoms. Semiconductors containing oxygen atoms tend to have a larger bandgap energy than the first semiconductor described above. The form of the oxygen-containing semiconductor in the second semiconductor is not clearly defined, but it may be, for example, Ga-OS, Ga2O3, etc.

[0040] The second semiconductor is made of alkali metal (M) in addition to Ga and S. a ) may further contain. The alkali metal contained in the second semiconductor may contain at least lithium. If the second semiconductor contains an alkali metal, the ratio of the number of alkali metal atoms to the sum of the number of alkali metal atoms and the number of Ga atoms may be, for example, 0.01 or more and less than 1, or 0.1 or more and 0.9 or less. Also, the ratio of the number of S atoms to the sum of the number of alkali metal atoms and the number of Ga atoms may be, for example, 0.25 or more and 0.75 or less.

[0041] The second semiconductor may further contain Ag in addition to Ga and S. When the second semiconductor contains Ag, the ratio of the number of Ag atoms to the sum of the number of Ga atoms may be, for example, 0.01 or more and less than 1, or 0.1 or more and 0.9 or less. Also, the ratio of the number of S atoms to the sum of the number of Ag atoms to the sum of the number of Ga atoms may be, for example, 0.25 or more and 0.75 or less.

[0042] If the second semiconductor further contains Ag in addition to Ga and S, the deposit containing the second semiconductor may have a uniform composition in the thickness direction or a composition that changes in the thickness direction. For example, the deposit containing the second semiconductor may have a composition in which the Ag content increases from the surface to the interior of the semiconductor nanoparticles.

[0043] The second semiconductor may have a crystal system familiar to that of the first semiconductor, and its lattice constant may be the same as or close to that of the first semiconductor. A second semiconductor with a familiar crystal system and a close lattice constant may provide good coverage around the first semiconductor. Here, a semiconductor whose lattice constant is a multiple of that of the first semiconductor is also considered to have a close lattice constant. For example, the first semiconductor described above is generally tetragonal, and familiar crystal systems for it include tetragonal and orthorhombic systems. If Ag-In-S is tetragonal, its lattice constants are 0.5828 nm, 0.5828 nm, and 1.119 nm, and it is preferable that the second semiconductor covering it is tetragonal or orthorhombic, and its lattice constant or a multiple thereof is close to that of Ag-In-S. Alternatively, the second semiconductor may be amorphous (non-crystalline).

[0044] Whether the second semiconductor is amorphous (non-crystalline) can be confirmed by observing the semiconductor nanoparticles with HAADF-STEM. Specifically, if the second semiconductor is amorphous (non-crystalline), a portion with a regular pattern, such as stripes or dots, will be observed in the center, while a portion surrounding it that does not exhibit a regular pattern will be observed in HAADF-STEM. According to HAADF-STEM, materials with a regular structure, such as crystalline materials, will be observed as images with a regular pattern, while materials without a regular structure, such as amorphous materials, will not be observed as images with a regular pattern. Therefore, if the second semiconductor is amorphous, it can be observed as a clearly different portion from the first semiconductor (which may have a crystalline structure such as a tetragonal system) that is observed as an image with a regular pattern.

[0045] Furthermore, when the second semiconductor consists of Ga-S, Ga is a lighter element than Ag and In, which are present in the first semiconductor. Therefore, in images obtained by HAADF-STEM, the second semiconductor tends to appear darker than the first semiconductor.

[0046] Whether the second semiconductor is amorphous can also be confirmed by observing the semiconductor nanoparticles of this embodiment with a high-resolution transmission electron microscope (HRTEM). In the image obtained with HRTEM, the first semiconductor portion is observed as a crystal lattice image (an image with a regular pattern), while the amorphous second semiconductor portion is not observed as a crystal lattice image. Although black and white contrast is observed, the regular pattern is not visible.

[0047] On the other hand, it is preferable that the second semiconductor does not form a solid solution with the first semiconductor. If the second semiconductor forms a solid solution with the first semiconductor, the two become one, and the mechanism of this embodiment, in which band-edge emission is obtained by placing the second semiconductor on the surface of the semiconductor nanoparticle, cannot be obtained. For example, it has been confirmed that even if zinc sulfide (Zn-S) in a stoichiometric or non-stoichiometric composition is placed on the surface of semiconductor nanoparticles containing the first semiconductor composed of Ag-In-S, band-edge emission cannot be obtained from the semiconductor nanoparticles. In relation to Ag-In-S, Zn-S satisfies the above conditions with respect to the band gap energy and gives type-I band alignment. Nevertheless, it is presumed that the reason why band-edge emission could not be obtained from the particular semiconductor was that the first semiconductor and ZnS formed a solid solution.

[0048] The particle size of the semiconductor nanoparticles may have an average particle size of, for example, 50 nm or less. From the viewpoint of ease of manufacturing and internal quantum efficiency of band edge emission, the average particle size is preferably in the range of 1 nm to 20 nm, more preferably 1.6 nm to 8 nm, and particularly preferably 2 nm to 7.5 nm.

[0049] The average particle size of semiconductor nanoparticles can be determined, for example, from TEM images taken using a transmission electron microscope (TEM). Specifically, the particle size of an individual particle is defined as the longest line segment within the particle, formed by connecting any two points on the outer circumference of the particle observed in the TEM image.

[0050] However, if the particle has a rod shape, the length of the minor axis is considered to be the particle size. Here, a rod-shaped particle is one that has a minor axis and a major axis perpendicular to the minor axis in the TEM image, and the ratio of the length of the major axis to the length of the minor axis is greater than 1.2. Rod-shaped particles are observed in the TEM image as, for example, a quadrilateral shape including a rectangle, an ellipse, or a polygon. The shape of the cross-section, which is the plane perpendicular to the major axis of the rod shape, may be, for example, a circle, an ellipse, or a polygon. Specifically, for a rod-shaped particle, the length of the major axis refers to the length of the longest line segment connecting any two points on the outer circumference of the particle in the case of an ellipse, and the length of the longest line segment that is parallel to the longest side that defines the outer circumference and connects any two points on the outer circumference of the particle in the case of a rectangle or polygon. The length of the minor axis refers to the length of the longest line segment that connects any two points on the outer circumference and is perpendicular to the line segment that defines the length of the major axis.

[0051] The average particle size of semiconductor nanoparticles is determined by measuring the particle size of all measurable particles observed in TEM images at magnifications between 50,000x and 150,000x, and taking the arithmetic mean of these particle sizes. Here, "measurable" particles are those whose entire contour can be observed in the TEM image. Therefore, particles whose contour is partially cut off in the TEM image are not considered measurable. If a single TEM image contains 100 or more measurable particles, the average particle size is determined using that TEM image. On the other hand, if a single TEM image contains fewer than 100 measurable particles, the imaging location is changed, additional TEM images are acquired, and the particle size of 100 or more measurable particles contained in two or more TEM images is measured to determine the average particle size.

[0052] In semiconductor nanoparticles, the portion consisting of the first semiconductor may be particulate, and may have an average particle size of, for example, 10 nm or less, particularly 8 nm or less, or less than 7.5 nm. The average particle size of the first semiconductor may be in the range of, for example, 1.5 nm or more and 10 nm or less, preferably 1.5 nm or more and less than 8 nm, or 1.5 nm or more and less than 7.5 nm. When the average particle size of the first semiconductor is below the above upper limit, the quantum size effect is easily obtained.

[0053] The thickness of the portion of the semiconductor nanoparticle consisting of the second semiconductor may be in the range of 0.1 nm to 50 nm, 0.1 nm to 10 nm, and especially in the range of 0.3 nm to 3 nm. When the thickness of the second semiconductor is greater than or equal to the lower limit, the effects of the arrangement of the second semiconductor in the semiconductor nanoparticle are sufficiently obtained, and band-edge emission is easily obtained.

[0054] The average particle size of the first semiconductor and the thickness of the second semiconductor may be determined by observing the semiconductor nanoparticles, for example, using HAADF-STEM. In particular, if the second semiconductor is amorphous, the thickness of the second semiconductor portion, which is easily observed as a separate part from the first semiconductor, can be easily determined by HAADF-STEM. In that case, the particle size of the first semiconductor can be determined according to the method described above for semiconductor nanoparticles. If the thickness of the second semiconductor is not constant, the smallest thickness is taken as the thickness of the second semiconductor in the semiconductor nanoparticle.

[0055] Semiconductor nanoparticles are preferably substantially tetragonal in their crystal structure. The crystal structure is identified by measuring the XRD pattern obtained by X-ray diffraction (XRD) analysis, as described above. Substantially tetragonal means that the ratio of the height of the main peak around 26°, which indicates tetragonality, to the height of the peaks around 48°, which indicate hexagonal and orthorhombic structures, is, for example, 10% or less, or 5% or less.

[0056] When semiconductor nanoparticles are irradiated with light of a wavelength in the range of 350 nm to less than 500 nm, they emit light with a longer wavelength than the irradiated light. The light emitted by semiconductor nanoparticles may include band-edge emission. The emission peak wavelength of the light emitted by semiconductor nanoparticles may be, for example, 500 nm to 820 nm. Preferably, the emission peak wavelength of the light emitted by semiconductor nanoparticles may be 500 nm or more, or 600 nm or more, and preferably 590 nm or less, or 820 nm or less.

[0057] The full width at half maximum (FWHM) of the emission peak in the emission spectrum of semiconductor nanoparticles may be, for example, 70 nm or less, 60 nm or less, 55 nm or less, or 50 nm or less. The lower limit of the FWHM of the emission peak may be, for example, 10 nm or more, or 20 nm or more. Also, the FWHM of the emission peak may be, for example, 250 meV or less, 210 meV or less, or 190 meV or less. The lower limit of the FWHM of the emission peak may be, for example, 35 meV or more, or 70 meV or more.

[0058] The emission of semiconductor nanoparticles may include defect emission (e.g., donor-acceptor emission) in addition to band-edge emission, but it is preferable that it be substantially band-edge emission only. Defect emission generally has a long emission lifetime and a broad spectrum, and its peak is located at a longer wavelength than the band-edge emission. Here, "substantially band-edge emission only" means that the purity of the band-edge emission component in the emission spectrum is 40% or more, preferably 60% or more, or even 90% or more. Here, "purity of the band-edge emission component" is expressed by the following formula when the peaks of the emission spectrum are separated into two peaks, the band-edge emission peak and the defect emission peak, and their areas are a1 and a2, respectively. Note that the shape of each peak is assumed to be a normal distribution. Purity of band-edge emission component (%) = a1 / (a1+a2)×100

[0059] If the emission spectrum contains no band-edge emission at all, i.e., only defect emission, the value is 0%. If the peak areas of band-edge emission and defect emission are the same, the value is 50%. If it contains only band-edge emission, the value is 100%.

[0060] The quantum efficiency of band-edge emission is measured using a quantum efficiency measuring device at an excitation wavelength of 450 nm and a temperature of 25°C. It is defined as the value obtained by multiplying the internal quantum efficiency calculated in the range of 506 nm to 882 nm by the purity of the band edge and dividing by 100. The quantum efficiency of band-edge emission of semiconductor nanoparticles may be, for example, 10% or more, preferably 20% or more, or 50% or more.

[0061] The band-edge emission emitted by semiconductor nanoparticles can be altered by changing the particle size of the semiconductor nanoparticles. For example, reducing the particle size of semiconductor nanoparticles tends to shift the peak wavelength of the band-edge emission to shorter wavelengths. Furthermore, reducing the particle size of semiconductor nanoparticles tends to reduce the full width at half maximum (FWHM) of the band-edge emission spectrum.

[0062] It is also preferable that the absorption spectrum or excitation spectrum (also called the fluorescence excitation spectrum) of the semiconductor nanoparticles exhibits an exciton peak. The exciton peak is a peak obtained by exciton generation, and its appearance in the absorption spectrum or excitation spectrum means that the particles have a small particle size distribution and few crystal defects, making them suitable for band-edge emission. The steeper the exciton peak, the more particles with uniform particle size and few crystal defects are contained in the aggregate of semiconductor nanoparticles. Therefore, the full width at half maximum of the emission is expected to be narrower, and the luminescence efficiency is expected to improve. In the absorption spectrum or excitation spectrum of semiconductor nanoparticles, the exciton peak is observed, for example, in the range of 350 nm to 1000 nm. The excitation spectrum to check for the presence or absence of the exciton peak may be measured by setting the observation wavelength to near the peak wavelength.

[0063] Diamine compounds A diamine compound is arranged on the surface of semiconductor nanoparticles to form a light-emitting material. The stability of the light-emitting material is improved by placing a diamine compound with high binding affinity to the semiconductor nanoparticles on its surface. The diamine compound may function as a ligand that binds to the surface of the semiconductor nanoparticles.

[0064] The diamine compound may be located on the surface of the second semiconductor. The diamine compound located on the surface of the semiconductor nanoparticle may be an aliphatic diamine compound. The diamine compound may be a compound having two carbon atoms to which two amino groups are each bonded, a single bond connecting the two carbon atoms to which the amino groups are bonded, or an aliphatic group and a substituent that substitutes for at least one of the carbon atoms to which the amino groups are bonded and at least one of the aliphatic group. Examples of substituents include optionally substituted alkyl groups, optionally substituted alkenyl groups, optionally substituted alkynyl groups, optionally substituted oxaalkyl groups, optionally substituted aryl groups, optionally substituted heterocyclic groups, etc., and may include at least one selected from the group consisting of these. Preferably, the substituent may include at least one selected from the group consisting of optionally substituted alkyl groups, optionally substituted alkenyl groups, and optionally substituted oxaalkyl groups. The number of substituents in the diamine compound may be, for example, 1 to 10, preferably 2 or more, or 4 or less. When there are 2 or more substituents in the diamine compound, each substituent may be the same or different. Also, any two substituents may be linked to each other to form a ring.

[0065] The diamine compound may have, for example, 0 to 4 carbon atoms connecting the carbon atoms to which the two amino groups are bonded, and preferably 1 or 2 carbon atoms. That is, the diamine compound may preferably be a 1,3-diamine compound or a 1,4-diamine compound.

[0066] The alkyl group in the alkyl group that may be substituted may be linear, branched, or cyclic, and may include both a cyclic structure and a linear or branched chain structure. The number of carbon atoms in the alkyl group may be, for example, 6 to 20, preferably 10 or more, or 12 or more, and preferably 18 or less, or 16 or less.

[0067] The alkenyl group portion of the alkenyl group, which may be substituted, may be linear, branched, or cyclic, and may include both cyclic and linear or branched chain structures. The number of carbon atoms in the alkenyl group portion may be, for example, 6 to 20, preferably 10 or more, or 12 or more, and preferably 18 or less, or 16 or less. The position of the double bond in the alkenyl group may be terminal or at any other position. The number of double bonds in the alkenyl group may be, for example, 1 to 4, preferably 2 or less.

[0068] The alkynyl group portion of the alkynyl group, which may be substituted, may be linear, branched, or cyclic, and may include both cyclic and linear or branched chain structures. The number of carbon atoms in the alkynyl group portion may be, for example, 6 to 20, preferably 10 or more, or 12 or more, and preferably 18 or less, or 16 or less. The position of the triple bond in the alkynyl group may be terminal or at any other position. The number of triple bonds in the alkynyl group may be, for example, 1 to 4, preferably 2 or less.

[0069] In the substituted oxaalkyl group, the oxaalkyl group may be one in which any methylene group in the substituted alkyl group is replaced with an oxygen atom. The oxaalkyl group may also be formed by linking two or more alkylene oxy groups having 2 to 6 carbon atoms, with a hydrogen atom or an alkyl group having 1 to 6 carbon atoms bonded to one end. The total number of carbon atoms in the oxaalkyl group may be, for example, 6 to 20, preferably 10 or more, or 12 or more, and preferably 18 or less, or 16 or less. The number of oxygen atom substitutions in the oxaalkyl group may be, for example, 2 to 10, preferably 4 or more, or 8 or less.

[0070] The substituted aryl group may have 6 to 20 carbon atoms in the aryl group portion, preferably 6, 10, 14, or 18. Examples of aryl groups include phenyl, naphthyl, and anthracenyl groups.

[0071] The heterocyclic group in the substituted heterocyclic group may be an aliphatic heterocyclic group or an aromatic heterocyclic group. Examples of heteroatoms included in the heterocyclic group include nitrogen, oxygen, sulfur, silicon, and phosphorus atoms. The heterocyclic group may contain two or more heteroatoms. The total number of carbon atoms constituting the heterocyclic group may be between 2 and 20, preferably between 2 and 10. Specific examples of heterocyclic groups include epoxy groups, pyridyl groups, and imidazolyl groups.

[0072] Substituents in the optionally substituted alkyl groups, optionally substituted alkenyl groups, optionally substituted alkynyl groups, optionally substituted oxaalkyl groups, optionally substituted aryl groups, and optionally substituted heterocyclic groups include, for example, halogen atoms such as fluorine and chlorine atoms, hydroxyl groups, thiol groups, epoxy groups, vinyl groups, acryloyl groups, methacryloyl groups, trimethoxysilyl groups, triethoxysilyl groups, trichlorosilyl groups, trifluoromethyl groups, pentafluoroethyl groups, heptafluoropropyl groups, and nonafluorobutyl groups. The number of substitutions may be, for example, 0 to 6, and preferably 2 or less.

[0073] In diamine compounds, substituents may be any two substituents linked to each other to form a ring. The number of members in the formed ring may be, for example, 3 to 8, preferably 5 or more, or 6 or less. The formed ring may be an aliphatic hydrocarbon ring consisting of hydrocarbons, or an aliphatic heterocycle containing heteroatoms. Specific examples of the formed ring include, for example, a cyclopentane ring, a cyclohexane ring, a tetrahydrofuran ring, and the like.

[0074] Diamine compounds may contain one or more chiral carbon atoms or chiral centers in their structural formula due to their substituents, and may have two or more stereoisomers. The diamine compounds described herein encompass all of these stereoisomers and mixtures containing them in any proportion. Furthermore, diamine compounds may have two or more geometric isomers in their structural formula due to carbon-carbon double bonds. The diamine compounds described herein encompass all of these geometric isomers and mixtures containing them in any proportion.

[0075] The diamine compound may have a structure represented by, for example, the following formula (1).

[0076] [ka]

[0077] In formula (1), each R independently represents at least one substituent or hydrogen atom selected from the group consisting of a C6 to C20 optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted alkynyl group, an optionally substituted oxaalkyl group, an optionally substituted aryl group, and an optionally substituted heterocyclic group, or an optionally substituted alkylene group in which two Rs are linked to form a ring, except when all Rs are hydrogen atoms. n represents a number between 2 and 6, inclusive.

[0078] Details regarding the optionally substituted alkyl group, optionally substituted alkenyl group, optionally substituted alkynyl group, optionally substituted oxaalkyl group, optionally substituted aryl group, and optionally substituted heterocyclic group in R of formula (1) are as previously described. In formula (1), R may preferably be at least one substituent or hydrogen atom selected from the group consisting of optionally substituted alkyl groups, alkenyl groups, and oxaalkyl groups.

[0079] Furthermore, the diamine compound may have a structure represented by any of the following formulas (1a) to (1g).

[0080] [ka]

[0081] In equations (1a) to (1g), R 1 Each independently represents at least one substituent or hydrogen atom selected from the group consisting of C6 to C20 optionally substituted alkyl groups, optionally substituted alkenyl groups, optionally substituted alkynyl groups, optionally substituted oxaalkyl groups, optionally substituted aryl groups and optionally substituted heterocyclic groups, or two R 1 These represent substituted alkylene groups that are linked to each other to form a ring. However, two R 1 Except when both are hydrogen atoms.

[0082] R from equation (1a) to (1g) 1 Details regarding the optionally substituted alkyl groups, optionally substituted alkenyl groups, optionally substituted alkynyl groups, optionally substituted oxaalkyl groups, optionally substituted aryl groups, and optionally substituted heterocyclic groups in R are as previously described. 1 R may be at least one substituent or hydrogen atom selected from the group consisting of preferably substituted alkyl groups, alkenyl groups, and oxaalkyl groups. 1 The alkyl group that may be substituted in the compound preferably has 6 to 18 carbon atoms, or 6 to 12 carbon atoms.

[0083] The diamine compound may be arranged individually or in combination of two or more types. Furthermore, the diamine compound may be obtained by purchase or other means, or it may be synthesized using known amination reactions such as the Gabriel reaction, reduction reactions of nitrogen-containing functional groups such as cyano groups, hydrolysis reactions, etc.

[0084] The content of the diamine compound in semiconductor nanoparticles may be, for example, 0.1% by mass or more and 50% by mass or less based on the total mass of the semiconductor nanoparticles. Preferably, the content of the diamine compound may be 1% by mass or more, or 20% by mass or less. The content of the diamine compound in semiconductor nanoparticles can be evaluated by organic elemental analysis.

[0085] Semiconductor nanoparticles may contain carbon atoms derived from diamine compounds. The carbon atom content in semiconductor nanoparticles may be, for example, 0.05% by mass or more and 45% by mass or less relative to the total mass of the semiconductor nanoparticles. Preferably, the carbon atom content may be 0.5% by mass or more, or 0.7% by mass or more, and preferably 18% by mass or less, or 16% by mass or less. The carbon atom content in semiconductor nanoparticles can be evaluated by organic elemental analysis.

[0086] The diamine compound may be positioned on at least a portion of the surface of the semiconductor nanoparticle, and preferably it may cover at least a portion of the surface of the semiconductor nanoparticle. The coverage rate of the semiconductor nanoparticle surface by the diamine compound may be, for example, 10% or more, preferably 50% or more, or 70% or more. The upper limit of the coverage rate may be, for example, 100% or less. The coverage rate is calculated as the ratio of the area of ​​the region covered with the diamine compound to the surface area of ​​the semiconductor nanoparticle.

[0087] The diamine compound may be a ligand that binds to the surface of semiconductor nanoparticles. The ligand is thought to be in equilibrium between being bound to the semiconductor nanoparticle (QD) and being unbound, for example, in a liquid medium, as shown below.

[0088] [ka]

[0089] When a light-emitting material containing semiconductor nanoparticles is washed, unbound ligands are removed from the system. As a result, some of the ligands bound to the semiconductor nanoparticles detach, and the system returns to an equilibrium state. Consequently, the quantum emission efficiency of the semiconductor nanoparticles is thought to decrease compared to before washing. The equilibrium in the above equation is shifted to the left as the binding of the ligand to the semiconductor nanoparticle is stronger. In other words, the stronger the binding to the semiconductor nanoparticle, the less likely the ligand is to detach by washing, and the less likely the quantum emission efficiency is to decrease. For example, if the retention rate of quantum emission efficiency is defined as shown in the equation below, the binding strength of the diamine compound (ligand) to the semiconductor nanoparticles can be evaluated using the retention rate of quantum emission efficiency.

[0090]

number

[0091] The emission quantum efficiency retention rate in the light-emitting material may be, for example, 50% or more. Preferably, the emission quantum efficiency retention rate may be 70% or more, or 80% or more.

[0092] In addition to diamine compounds, surface modifiers other than diamine compounds may be placed on the surface of semiconductor nanoparticles. Specific examples of surface modifiers include nitrogen-containing compounds having hydrocarbon groups with 4 to 20 carbon atoms, sulfur-containing compounds having hydrocarbon groups with 4 to 20 carbon atoms, and oxygen-containing compounds having hydrocarbon groups with 4 to 20 carbon atoms, as well as compounds containing phosphorus with a negative oxidation state (hereinafter also referred to as "specific modifiers"). Including specific modifiers among the surface modifiers placed on the surface of semiconductor nanoparticles may further improve the quantum efficiency of the band-edge emission of the semiconductor nanoparticles.

[0093] The specific modifiers contain phosphorus (P), a Group 15 element with a negative oxidation state. The oxidation state of P changes depending on the substitution state of P: -1 when one hydrogen atom or hydrocarbon group is bonded to P, and +1 when one oxygen atom is bonded via a single bond. For example, the oxidation state of P in trialkylphosphines and triarylphosphines is -3, and in trialkylphosphine oxides and triarylphosphine oxides it is -1.

[0094] The specific modifier may contain, in addition to P having a negative oxidation state, other Group 15 elements. Examples of other Group 15 elements include N, As, Sb, etc.

[0095] The specific modifier may be, for example, a phosphorus-containing compound having a hydrocarbon group with 4 to 20 carbon atoms. Examples of hydrocarbon groups with 4 to 20 carbon atoms include linear or branched saturated aliphatic hydrocarbon groups such as n-butyl, isobutyl, n-pentyl, n-hexyl, octyl, ethylhexyl, decyl, dodecyl, tetradecyl, hexadecyl, and octadecyl groups; linear or branched unsaturated aliphatic hydrocarbon groups such as oleyl groups; alicyclic hydrocarbon groups such as cyclopentyl and cyclohexyl groups; aromatic hydrocarbon groups such as phenyl and naphthyl groups; and arylalkyl groups such as benzyl and naphthylmethyl groups. Of these, saturated aliphatic and unsaturated aliphatic hydrocarbon groups are preferred. If the specific modifier has multiple hydrocarbon groups, they may be the same or different.

[0096] Specific examples of specific modifiers include tributylphosphine, triisobutylphosphine, tripentylphosphine, trihexylphosphine, trioctylphosphine, tris(ethylhexyl)phosphine, tridecylphosphine, tododecylphosphine, tritetradecylphosphine, trihexadecylphosphine, trioctadecylphosphine, triphenylphosphine, tributylphosphine oxide, triisobutylphosphine oxide, tripentylphosphine oxide, trihexylphosphine oxide, trioctylphosphine oxide, tris(ethylhexyl)phosphine oxide, tridecylphosphine oxide, tododecylphosphine oxide, tritetradecylphosphine oxide, trihexadecylphosphine oxide, trioctadecylphosphine oxide, triphenylphosphine oxide, etc., and at least one selected from the group consisting of these is preferred.

[0097] The surface of the shell may be surface-modified with other surface modifiers in addition to the specific modifier. Examples of other surface modifiers include nitrogen-containing compounds having hydrocarbon groups with 4 to 20 carbon atoms, sulfur-containing compounds having hydrocarbon groups with 4 to 20 carbon atoms, and oxygen-containing compounds having hydrocarbon groups with 4 to 20 carbon atoms. Examples of nitrogen-containing compounds include amines and amides, examples of sulfur-containing compounds include thiols, and examples of oxygen-containing compounds include fatty acids.

[0098] Other preferred surface modifiers include nitrogen-containing compounds having hydrocarbon groups with 4 to 20 carbon atoms, and sulfur-containing compounds having hydrocarbon groups with 4 to 20 carbon atoms. Examples of nitrogen-containing compounds include alkylamines such as n-butylamine, isobutylamine, n-pentylamine, n-hexylamine, octylamine, decylamine, dodecylamine, tetradecylamine, hexadecylamine, and octadecylamine, as well as alkenylamines such as oleylamine. N-tetradecylamine and oleylamine are particularly preferred due to their availability in high purity and their boiling points exceeding 290°C. Examples of sulfur-containing compounds include n-butanethiol, isobutanethiol, n-pentanethiol, n-hexanethiol, octanthiol, decanethiol, dodecanethiol, hexadecanethiol, and octadecanethiol.

[0099] Surface modifiers other than diamine compounds may be used in combination of two or more different types. For example, one compound selected from the nitrogen-containing compounds exemplified above (e.g., oleylamine) may be used in combination with one compound selected from the sulfur-containing compounds exemplified above (e.g., dodecanethiol).

[0100] When a light-emitting material is irradiated with light of a wavelength in the range of 350 nm to less than 500 nm, it emits light with a longer wavelength than the irradiated light due to the semiconductor nanoparticles it contains. The light emitted by the light-emitting material may include band-edge emission. The emission peak wavelength of the light emitted by the light-emitting material may be, for example, 500 nm to 820 nm. Preferably, the emission peak wavelength of the light emitted by the light-emitting material may be 500 nm or more, or 600 nm or more, and preferably 590 nm or less, or 820 nm or less.

[0101] The full width at half maximum (FWHM) of the emission peak in the emission spectrum of the light-emitting material may be, for example, 70 nm or less, 60 nm or less, 55 nm or less, or 50 nm or less. The lower limit of the FWHM of the emission peak may be, for example, 10 nm or more, or 20 nm or more. Also, the FWHM of the emission peak may be, for example, 250 meV or less, 210 meV or less, or 190 meV or less. The lower limit of the FWHM of the emission peak may be, for example, 35 meV or more, or 70 meV or more.

[0102] The emission quantum efficiency of a light-emitting material is measured using a quantum efficiency measuring device at an excitation wavelength of 450 nm and a temperature of 25°C, and is defined as the internal quantum efficiency calculated in the range of 500 nm to 950 nm. The emission quantum efficiency of a light-emitting material may be, for example, 10% or more, preferably 20% or more, or 50% or more.

[0103] The luminescent material may be in powder form or dispersed in a liquid medium. The liquid medium may be a halogenated solvent such as chloroform, or a hydrocarbon solvent such as toluene, cyclohexane, hexane, pentane, or octane. The liquid medium may also contain a polymerizable compound, or be substantially polymerizable. Here, "substantially polymerizable" means that the content of solvents other than the polymerizable compound in the liquid medium is 10% by mass or less, or 5% by mass or less. The dispersion of the luminescent material tends to suppress the decrease in luminescence quantum efficiency.

[0104] The polymerizable compound used as the liquid medium can be any liquid compound having polymerizable groups. Examples of polymerizable groups include vinyl groups, (meth)acrylic groups, and epoxy groups. Specific examples of polymerizable compounds include β-carboxyethyl acrylate, isobornyl (meth)acrylate, methoxyphenyl (meth)acrylate, ethoxyphenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and nonanediol di(meth)acrylate.

[0105] When the liquid medium contains a polymerizable compound, the concentration of the luminescent material in the dispersion may be controlled by the absorbance of the dispersion. Specifically, using a solvent for absorbance measurement, the concentration can be set such that the absorbance at 450 nm of a sample diluted 80 times by volume is between 0.50 and 1.50. This tends to more effectively suppress the decrease in emission quantum efficiency. A dispersion containing a luminescent material and a polymerizable compound can be used, for example, in the manufacture of a wavelength conversion material containing a luminescent material.

[0106] Method for manufacturing luminescent materials The light-emitting material can be manufactured by bringing a second semiconductor nanoparticle, which contains a first semiconductor and has a second semiconductor disposed on its surface, into contact with a diamine compound, thereby distributing the diamine compound on the surface of the second semiconductor. In other words, the method for manufacturing the light-emitting material may include a contact step of bringing the second semiconductor nanoparticle and the diamine compound into contact.

[0107] The second semiconductor nanoparticle may have other surface modifiers besides the diamine compound on its surface. By bringing the second semiconductor nanoparticle into contact with the diamine compound, at least a portion of the other surface modifier is replaced by the diamine compound, forming a light-emitting material that includes a third semiconductor nanoparticle on which the diamine compound is disposed on the surface of the second semiconductor nanoparticle.

[0108] Contact between the second semiconductor nanoparticles and the diamine compound can be carried out, for example, by mixing a dispersion of the second semiconductor nanoparticles with the diamine compound. Alternatively, it may be carried out by mixing a solution of the diamine compound with the second semiconductor nanoparticles.

[0109] The second semiconductor nanoparticle comprises a first semiconductor nanoparticle containing a first semiconductor comprising a group 11 element which may contain silver (Ag) and copper (Cu), a group 13 element which contains at least one of indium (In) and gallium (Ga), and a group 16 element which contains sulfur (S), and the second semiconductor which contains at least gallium (Ga) and sulfur (S) is disposed on its surface. Details of the first and second semiconductors are as previously described. Furthermore, for the method of manufacturing the second semiconductor nanoparticle, refer to, for example, the descriptions in Japanese Patent Publication No. 2018-39971, Japanese Patent Publication No. 2018-141141, International Publication No. 2020 / 162622, Japanese Patent Application No. 2021-036717, Japanese Patent Application No. 2021-126859, etc.

[0110] Examples of liquid media constituting the dispersion of the second semiconductor nanoparticles include halogenated solvents such as chloroform and chlorobenzene, hydrocarbon solvents such as toluene, cyclohexane, hexane, pentane, octane, and xylene, and alcoholic solvents such as methanol and ethanol. The liquid media may be used alone or as a mixture of two or more. Furthermore, the liquid media constituting the solution of the diamine compound is the same as the liquid media constituting the dispersion of the second semiconductor nanoparticles.

[0111] The concentration of the second semiconductor nanoparticles in the dispersion of the second semiconductor nanoparticles is, for example, the concentration of the particles in the dispersion, for example, 5.0 × 10⁻⁶. -7 mol / L or more 5.0×10 -5 mol / L or less, especially 1.0 × 10⁻⁶ -6 mol / L or more, 1.0×10 -5 The dispersion may be prepared to be mol / L or less. Here, the particle concentration is the molar concentration when one particle is considered as a large molecule, and the number of nanoparticles contained in 1 L of the dispersion is Avogadro's number (N). A= 6.022 × 10 23 It is equal to the value obtained by dividing by ).

[0112] The amount of diamine compound used in contact with the second semiconductor nanoparticles may be, for example, 1 μmol to 100 mmol per 10 nmol of the amount of substance of the second semiconductor nanoparticles as particles. The amount of diamine compound used may preferably be 10 μmol or more, or 0.1 mmol or more, and preferably 10 mmol or less, or 1 mmol or less. Here, the amount of substance as particles is the molar amount when one particle is considered to be a large molecule, and the number of nanoparticles contained in the dispersion is Avogadro's number (N). A = 6.022 × 10 23 It is equal to the value obtained by dividing by ).

[0113] Furthermore, the concentration of the second semiconductor nanoparticles in the dispersion may be, for example, a concentration such that the absorbance at 450 nm is between 0.01 and 1000. In this case, the amount of diamine compound used to contact the second semiconductor nanoparticles may be, for example, between 0.001 mmol and 10 mmol per 600 μl of dispersion.

[0114] The contact temperature between the second semiconductor nanoparticle and the diamine compound may be, for example, 0°C to 100°C, preferably 20°C or higher, or 50°C or lower. The contact time between the second semiconductor nanoparticle and the diamine compound may be, for example, 1 hour to 100 hours, preferably 10 hours or higher, or 50 hours or lower.

[0115] The third semiconductor nanoparticles obtained by contacting the second semiconductor nanoparticles with a diamine compound may undergo purification processes such as washing and drying. In other words, the method for producing the light-emitting material may include a washing process in addition to the contact process. The washing process can be carried out, for example, by adding an organic solvent such as alcohol to a dispersion of semiconductor nanoparticles, and then recovering the third semiconductor nanoparticles as a precipitate by centrifugation. The washing process may be performed only once or multiple times as necessary. When the washing process is performed multiple times, the precipitate can be dispersed in a suitable liquid medium, and then recovered as a precipitate by adding an organic solvent such as alcohol and centrifugation. Examples of alcohols that can be used in the washing process include lower alcohols having 1 to 4 carbon atoms, such as methanol, ethanol, and n-propyl alcohol. When dispersing the precipitate in a liquid medium, halogenated solvents such as chloroform, hydrocarbon solvents such as toluene, cyclohexane, hexane, pentane, and octane may be used as the liquid medium.

[0116] The precipitate containing the third semiconductor nanoparticles after the washing treatment may be subjected to a drying treatment. The drying treatment can be carried out, for example, by vacuum degassing, natural drying, or a combination of vacuum degassing and natural drying. Natural drying can be carried out, for example, by leaving it in the atmosphere at room temperature and pressure, in which case it may be left for 20 hours or more, for example, about 30 hours.

[0117] The precipitate containing the third semiconductor nanoparticles after the washing treatment may be converted into a dispersion of the third semiconductor nanoparticles by adding a liquid medium. Examples of liquid mediums include the halogenated solvents and hydrocarbon solvents described above. The liquid medium may also contain polymerizable compounds as needed, or may be substantially polymerizable compounds. Details of the polymerizable compounds are as described above.

[0118] A dispersion containing third semiconductor nanoparticles and a polymerizable compound can be prepared by adding the polymerizable compound to the dried third semiconductor nanoparticles after washing and mixing. Adding the polymerizable compound to the dried third semiconductor nanoparticles can suppress the decrease in the emission quantum efficiency of the third semiconductor nanoparticles. The concentration of third semiconductor nanoparticles in the dispersion may be adjusted, for example, so that the absorbance at 450 nm of a sample diluted 80 times by volume with an absorbance measuring solvent such as chloroform is between 0.5 and 1.5, or around 1.0. This makes it possible to obtain a light-emitting material with high luminescence efficiency.

[0119] In one embodiment, a method for producing a light-emitting material may include: a first step of heat-treating a first mixture comprising, for example, a Group 11 element source that may also contain silver (Ag) and copper (Cu), a Group 13 element source that may contain at least one of indium (In) and gallium (Ga), and a Group 16 element source that may contain sulfur (S), to obtain first semiconductor nanoparticles comprising a first semiconductor; a second step of heat-treating a dispersion containing the first semiconductor nanoparticles, a Group 13 element source that may contain gallium (Ga), and a Group 16 element source that may contain sulfur (S), to obtain second semiconductor nanoparticles having a second semiconductor disposed on their surface; and a third step of contacting the second semiconductor nanoparticles with a diamine compound to obtain third semiconductor nanoparticles having a diamine compound disposed on their surface.

[0120] In the first step, a first mixture comprising a Group 11 element source containing silver (Ag) and possibly copper (Cu), a Group 13 element source containing at least one of indium (In) and gallium (Ga), and a Group 16 element source containing sulfur (S) is heat-treated to obtain first semiconductor nanoparticles containing a first semiconductor.

[0121] The Group 11 and Group 13 element sources included in the first mixture may be organic acid salts or inorganic acid salts. Specifically, examples of inorganic acid salts include nitrates, sulfates, hydrochlorides, and sulfonates. Examples of organic acid salts include formates, acetates, oxalic acid, and acetylacetonates. The Group 11 and Group 13 element sources may preferably be at least one selected from the group consisting of these salts, and more preferably at least one selected from the group consisting of organic acid salts such as acetates and acetylacetonates, as these have high solubility in organic solvents and allow the reaction to proceed more uniformly. The first mixture may contain one Group 11 element source and one Group 13 element source each, or it may contain two or more of each in combination. Furthermore, the Group 13 element source in the first mixture may contain at least one selected from the group consisting of In salts and Ga salts, and may contain at least one Ga salt and further contain at least one In salt. Furthermore, the Group 11 element source in the first mixture may include at least one selected from the group consisting of Ag salts and Cu salts, and may include at least one Ag salt and further include at least one Cu salt.

[0122] When sulfur (S) is used as a constituent element of the first semiconductor as a Group 16 element, elemental sulfur such as high-purity sulfur can be used. Alternatively, sulfur-containing compounds can be used. Examples of sulfur-containing compounds include thiols such as n-butanethiol, isobutanethiol, n-pentanethiol, n-hexanethiol, octanthiol, decanethiol, dodecanethiol, hexadecanethiol, and octadecanethiol; disulfides such as dibenzyl sulfide; β-dithiones such as 2,4-pentanedithion; dithiols such as 1,2-bis(trifluoromethyl)ethylene-1,2-dithiol; dialkyldithiocarbamides such as diethyldithiocarbamide; thiourea, 1,3-dialkylthiourea having an alkyl group with 1 to 18 carbon atoms, 1,1-dialkylthiourea, alkylthiourea, 1,1,3-trialkylthiourea, and 1,1,3,3-tetraalkylthiourea. As a source of Group 16 elements, sulfur-containing compounds soluble in organic solvents are preferred, and from the viewpoint of solubility and reactivity, 1,3-dialkylthiourea is preferably used. The alkyl group of the alkylthiourea preferably has 1 to 12 carbon atoms, more preferably 1 to 8, more preferably 1 to 6, more preferably 1 to 4, and still more preferably 1 to 3. If the alkylthiourea has multiple alkyl groups, they may be the same or different.

[0123] The Group 16 element source contains at least S. The ratio of the number of S atoms to the total number of Group 16 elements contained in the Group 16 element source may be, for example, 90% or more, preferably 95% or more, or 99% or more. In other words, the Group 16 element source may be substantially an S source.

[0124] The content ratios of the Group 11, Group 13, and Group 16 element sources in the first mixture may be appropriately selected according to the desired composition. In this case, the content ratios of the Group 11, Group 13, and Group 16 element sources do not need to be consistent with the stoichiometric ratios.

[0125] The first mixture may contain at least one organic solvent. Examples of organic solvents in the first mixture include amines having a hydrocarbon group having 4 to 20 carbon atoms, such as alkylamines or alkenylamines having 4 to 20 carbon atoms; thiols having a hydrocarbon group having 4 to 20 carbon atoms, such as alkylthiols or alkenylthiols having 4 to 20 carbon atoms; and phosphines having a hydrocarbon group having 4 to 20 carbon atoms, such as alkylphosphines or alkenylphosphines having 4 to 20 carbon atoms. It is preferable to include at least one selected from the group consisting of these. These organic solvents may, for example, ultimately surface-modify the resulting first semiconductor nanoparticles. Two or more organic solvents may be used in combination. For example, a mixed solvent may be used that combines at least one selected from thiols having a hydrocarbon group having 4 to 20 carbon atoms and at least one selected from amines having a hydrocarbon group having 4 to 20 carbon atoms. These organic solvents may also be used in combination with other organic solvents. When the organic solvent contains the thiol and the amine, the volume ratio of thiol to amine (thiol / amine) is, for example, greater than 0 and 1 or less, and preferably 0.007 or more and 0.2 or less.

[0126] A first aspect of the first step may include preparing a first mixture containing a group 11 element source, a group 13 element source, a group 16 element source, and an organic solvent, and heat-treating the prepared first mixture. In the first aspect of the first step, the heat treatment of the first mixture generates first semiconductor nanoparticles containing a first semiconductor in the organic solvent. The heat treatment temperature of the first mixture is, for example, 230°C to 310°C, preferably higher than 260°C and 310°C or lower, and more preferably 290°C to 310°C. The heat treatment time is, for example, 5 minutes to 20 minutes, preferably 5 minutes to 15 minutes. The heat treatment of the mixture may be carried out at two or more temperatures. For example, it may be heated at a temperature of 30°C to 155°C for 1 minute to 15 minutes, and then heated at a temperature of 230°C to 310°C for 5 minutes to 20 minutes.

[0127] A second aspect of the first step may include preparing a premixture containing a group 11 element source, a group 13 element source, and an organic solvent; raising the temperature of the premixture to a temperature in the range of 120°C to 300°C; and adding a group 16 element source to the heated premixture. In the second aspect of the first step, a first mixture is formed by adding a group 16 element source to a premixture heated to a predetermined temperature, and this mixture is heat-treated to generate first semiconductor nanoparticles containing a first semiconductor in an organic solvent.

[0128] The temperature reached by heating the premixture is preferably 125°C or higher, 130°C or higher, or 135°C or higher, and preferably 175°C or lower, 160°C or lower, or 150°C or lower. The heating rate is, for example, 1°C / min or more and 50°C / min or less, and preferably 10°C / min or more and 50°C / min or less.

[0129] The addition of the Group 16 element source to the premixture may be done gradually, such that the rate of increase in the ratio of the number of Group 16 elements to the total number of Group 11 elements in the mixture is 10 / min or less. The rate of increase in the ratio of the number of Group 16 elements to the number of Group 11 elements in the premixture (Group 16 element / Group 11 element ratio) is calculated, for example, by subtracting the ratio at a certain point in time from the ratio at that unit time and dividing by the value obtained by converting the unit time to minutes. The unit time can be arbitrarily selected, for example, between 1 second and 1 minute. From the viewpoint of controlling the particle growth of nanoparticles, the rate of increase in the ratio of the number of Group 16 elements to the number of Group 11 elements in the premixture is preferably 0.0001 / min or more and 2 / min or less, and may be 0.0001 / min or more and 1 / min or less, 0.001 / min or more and 0.2 / min or less, or 0.001 / min or more and 0.1 / min or less. Furthermore, it is preferable that the flow rate is 0.0002 / min or more and 2 / min or less, or 0.002 / min or more and 0.2 / min or less.

[0130] The addition of the Group 16 element source may be carried out so that the amount added per unit time remains approximately constant over the required time. That is, the amount added per unit time may be obtained by dividing the total amount of the Group 16 element source by the number obtained by dividing the required time by the unit time. The unit time can be, for example, 1 second, 5 seconds, 10 seconds, 30 seconds, or 1 minute. The Group 16 element source may be added continuously or in stages. The Group 16 element source may also be added to the premixture, for example, under an inert gas atmosphere.

[0131] The heat treatment atmosphere should preferably be an inert atmosphere, particularly an argon atmosphere or a nitrogen atmosphere. By using an inert atmosphere, the formation of oxide by-products and oxidation of the surface of the first semiconductor nanoparticles can be reduced or prevented.

[0132] After the generation of the first semiconductor nanoparticles is complete, the obtained first semiconductor nanoparticles may be separated from the treated organic solvent and, if necessary, further purified. The purification of the first semiconductor nanoparticles can be carried out in the same manner as the washing treatment of the third semiconductor nanoparticles described above.

[0133] In the second step, a dispersion containing first semiconductor nanoparticles containing a first semiconductor, a nanoparticle mixture containing a group 13 element source containing gallium (Ga), and a group 16 element source containing sulfur (S) is prepared, and the prepared nanoparticle mixture is heat-treated to obtain second semiconductor nanoparticles in which a second semiconductor is arranged on the surface.

[0134] The solvent for dispersing the first semiconductor nanoparticles can be any organic solvent. The organic solvent can be a surface modifier or a solution containing a surface modifier. For example, the organic solvent can be at least one selected from nitrogen-containing compounds having hydrocarbon groups with 4 to 20 carbon atoms. Alternatively, it can be at least one selected from sulfur-containing compounds having hydrocarbon groups with 4 to 20 carbon atoms. Alternatively, it can be a combination of at least one selected from nitrogen-containing compounds having hydrocarbon groups with 4 to 20 carbon atoms and at least one selected from sulfur-containing compounds having hydrocarbon groups with 4 to 20 carbon atoms. As nitrogen-containing compounds, n-tetradecylamine, oleylamine, etc. are particularly preferred because they are readily available in particularly high purity and have a boiling point exceeding 290°C. As sulfur-containing compounds, dodecanethiol, etc., are preferred. Specific organic solvents include oleylamine, n-tetradecylamine, dodecanethiol, or combinations thereof.

[0135] The dispersion of the first semiconductor nanoparticles has a particle concentration in the dispersion that is, for example, 5.0 × 10⁻⁶ -7 5.0 × 10⁻⁶ moles / liter or more -5 moles / liter or less, especially 1.0 × 10⁻⁶ -6 Moles / liter or more, 1.0 × 10 -5 The dispersion may be prepared to a concentration of less than or equal to moles / liter. If the proportion of particles in the dispersion is too small, it becomes difficult to recover the product through the aggregation and precipitation process by the poor solvent. If it is too large, the proportion of Ostwald maturation and fusion by collision of the core-constituting materials increases, and the particle size distribution tends to broaden. The particle concentration is as previously described.

[0136] The Group 13 element source is, for example, an organic salt, inorganic salt, or organometallic compound of a Group 13 element. Specifically, examples include nitrates, acetates, sulfates, hydrochlorides, sulfons, and acetylacetonate complexes containing a Group 13 element, with organic salts such as acetates or organometallic compounds being preferred. Organic salts and organometallic compounds have high solubility in organic solvents, which facilitates more uniform reaction. The Group 13 element source contains at least Ga. The ratio of the number of Ga atoms to the total number of Group 13 elements contained in the Group 13 element source may be, for example, 90% or more, preferably 95% or more, or 99% or more. In other words, the Group 13 element source may be substantially a Ga source.

[0137] A Group 16 element source is either a Group 16 element in its pure form or a compound containing a Group 16 element. For example, when sulfur (S) is used as the constituent element of the second semiconductor as the Group 16 element, pure sulfur such as high-purity sulfur can be used, or sulfur-containing compounds such as n-butanethiol, isobutanethiol, n-pentanethiol, n-hexanethiol, octanthiol, decanethiol, dodecanethiol, hexadecanethiol, octadecanethiol, etc., disulfides such as dibenzyl sulfide, thiourea, 1,3-dimethylthiourea, thiocarbonyl compounds, etc. can be used. The Group 16 element source contains at least S. The ratio of the number of S atoms to the total number of Group 16 elements contained in the Group 16 element source may be, for example, 90% or more, preferably 95% or more, or 99% or more. That is, the Group 16 element source may be substantially an S source.

[0138] When oxygen (O) is used as a constituent element of the second semiconductor as a Group 16 element, alcohols, ethers, carboxylic acids, ketones, and N-oxide compounds may be used as sources of Group 16 elements. When selenium (Se) is used as a constituent element of the second semiconductor as a Group 16 element, elemental selenium, selenide phosphine oxide, organic selenium compounds (such as dibenzyl diselenide and diphenyl diselenide), or compounds such as hydrides may be used as sources of Group 16 elements. When tellurium (Te) is used as a constituent element of the second semiconductor as a Group 16 element, elemental tellurium, telluride phosphine oxide, or hydrides may be used as sources of Group 16 elements.

[0139] As a method for adding the Group 13 and Group 16 element sources to a dispersion, for example, a mixture may be prepared by dispersing or dissolving the Group 13 and Group 16 element sources in an organic solvent, and this mixture may be added to the dispersion in small amounts, for example, by dropwise addition. In this case, the mixture may be added at a rate of 0.1 mL / hour to 10 mL / hour, particularly 1 mL / hour to 5 mL / hour. Alternatively, the mixture may be added to a heated dispersion. Specifically, for example, the dispersion may be heated so that its peak temperature is between 200°C and 310°C, and after reaching the peak temperature, the mixture may be added in small amounts while maintaining the peak temperature, and then the temperature may be lowered to form the second semiconductor on the surface of the first semiconductor nanoparticles (slow injection method). The peak temperature may be maintained as needed even after the addition of the mixture is completed.

[0140] When the peak temperature is above the aforementioned temperature, the surface modifier modifying the first semiconductor nanoparticles tends to desorb sufficiently, or the chemical reaction for the generation of the second semiconductor tends to proceed sufficiently, resulting in sufficient formation of the second semiconductor. When the peak temperature is below the aforementioned temperature, alteration of the first semiconductor nanoparticles is suppressed, and good band-edge emission tends to be obtained. The time for maintaining the peak temperature can be between 1 minute and 300 minutes in total from the start of adding the mixed solution, and particularly between 10 minutes and 120 minutes. The peak temperature maintenance time is selected in relation to the peak temperature; a longer maintenance time when the peak temperature is lower, and a shorter maintenance time when the peak temperature is higher, tends to facilitate the formation of a good second semiconductor layer. The heating rate and cooling rate are not particularly limited, and cooling may be performed, for example, by stopping heating by a heat source (e.g., electric heater) after maintaining the peak temperature for a predetermined time and allowing it to cool.

[0141] Alternatively, the Group 13 and Group 16 element sources may be added directly and in their entirety to the dispersion. Then, the dispersion containing the Group 13 and Group 16 element sources may be heated to form and arrange the second semiconductor on the surface of the first semiconductor nanoparticles (heating-up method). Specifically, the dispersion containing the Group 13 and Group 16 element sources may be heated, for example, by gradually increasing the temperature so that the peak temperature is between 200°C and 310°C, holding it at the peak temperature for between 1 minute and 300 minutes, and then gradually decreasing the temperature. The heating rate may be, for example, between 1°C / min and 50°C / min, and the cooling rate may be, for example, between 1°C / min and 100°C / min. Alternatively, the heating may be done without particularly controlling the heating rate to reach a predetermined peak temperature, or the cooling may be done by stopping the heating source and allowing it to cool, rather than performing the cooling at a constant rate. The advantage of having the peak temperature within the aforementioned range is as explained in the method of adding the above-mentioned mixture (slow injection method).

[0142] The heating-up method tends to produce second semiconductor nanoparticles that exhibit stronger band-edge emission compared to the slow-injection method used to form the second semiconductor.

[0143] Regardless of the method used to add the Group 13 and Group 16 element sources, the charging ratio of the two may be determined in accordance with the stoichiometric composition ratio of the semiconductor compound consisting of the Group 13 and Group 16 elements, and does not necessarily have to be the stoichiometric composition ratio. If the charging ratio is not the stoichiometric composition ratio, the raw materials may be charged in excess of the amount of the target second semiconductor produced. For example, the amount of Group 16 element source may be less than the stoichiometric composition ratio, and the charging ratio may be 1:1 (Group 13:Group 16). For example, when using a Ga source as the Group 13 element source and an S source as the Group 16 element source, the charging ratio is preferably 1:1.5 (Ga:S) to 1:1, corresponding to the composition formula Ga2S3.

[0144] Furthermore, the amount of the first semiconductor nanoparticles present in the dispersion is selected considering the amount of first semiconductor nanoparticles contained in the dispersion, so that the second semiconductor of the desired thickness is arranged on the first semiconductor nanoparticles present in the dispersion. For example, the amount of the group 13 element source and the group 16 element source may be determined so that for every 10 nmol of first semiconductor nanoparticles, a compound semiconductor with a stoichiometric composition consisting of group 13 and group 16 elements is produced in an amount of 1 μmol to 10 mmol, particularly 5 μmol to 1 mmol. The amount of substance as particles is as previously described.

[0145] In the method for producing semiconductor nanoparticles, it is preferable to use gallium acetylacetonate as the source of Group 13 elements, elemental sulfur, thiourea, or dibenzyl disulfide as the source of Group 16 elements, and a mixture of oleylamine and dodecanethiol as the dispersion to form a second semiconductor containing gallium sulfide.

[0146] Furthermore, using a heating-up method with a mixture of oleylamine and dodecanethiol in the dispersion yields second semiconductor nanoparticles that give an emission spectrum in which the intensity of the broad peak originating from defect emission is sufficiently smaller than the intensity of the band-edge emission peak. This trend is also significantly observed when a gallium source is used as the group 13 element source.

[0147] In this way, a second semiconductor is placed on the surface of a first semiconductor nanoparticle to form a second semiconductor nanoparticle. The obtained second semiconductor nanoparticle may be separated from the solvent and, if necessary, further purified and dried. The methods for separation, purification, and drying have been described above, so a detailed explanation is omitted here.

[0148] In the third step, the second semiconductor nanoparticles are brought into contact with the diamine compound to obtain third semiconductor nanoparticles on which the diamine compound is arranged on the surface. The contact between the second semiconductor nanoparticles and the diamine compound has been explained earlier, so a detailed explanation will be omitted here.

[0149] Light-emitting device The light-emitting device comprises a wavelength conversion member containing a light-emitting material including the aforementioned semiconductor nanoparticles, and a semiconductor light-emitting element. With this light-emitting device, for example, a portion of the light emitted from the semiconductor light-emitting element is absorbed by the semiconductor nanoparticles, resulting in the emission of longer wavelength light. The light from the semiconductor nanoparticles and the remainder of the light emitted from the semiconductor light-emitting element are then mixed, and this mixed light can be used as the light emitted by the light-emitting device.

[0150] Specifically, a light-emitting device that emits white light can be obtained by using a semiconductor light-emitting element that emits blue-violet or blue light with a peak wavelength of approximately 400 nm to 490 nm, and semiconductor nanoparticles that absorb blue light and emit yellow light. Alternatively, a white light-emitting device can also be obtained by using two types of semiconductor nanoparticles: one that absorbs blue light and emits green light, and another that absorbs blue light and emits red light.

[0151] Alternatively, a white light-emitting device can be obtained by using a semiconductor light-emitting element that emits ultraviolet light with a peak wavelength of 400 nm or less, and by using three types of semiconductor nanoparticles that absorb ultraviolet light and emit blue, green, and red light, respectively. In this case, it is desirable to have all the light from the light-emitting element absorbed and converted by the semiconductor nanoparticles so that the ultraviolet light emitted from the light-emitting element does not leak to the outside.

[0152] Alternatively, by using a material that emits blue-green light with a peak wavelength of approximately 490 nm to 510 nm, and using a light-emitting material that absorbs blue-green light and emits red light, a light-emitting device that emits white light can be obtained.

[0153] Alternatively, by using a semiconductor light-emitting element that emits visible light, for example, one that emits red light with a wavelength of 700 nm to 780 nm, and using a light-emitting material that absorbs visible light and emits near-infrared light, it is also possible to obtain a light-emitting device that emits near-infrared light.

[0154] The luminescent material may be used in combination with other semiconductor quantum dots, or with other phosphors that are not quantum dots (e.g., organic or inorganic phosphors). Examples of other semiconductor quantum dots include binary semiconductor quantum dots. Examples of phosphors that are not quantum dots include garnet-based phosphors such as aluminum garnet. Examples of garnet-based phosphors include yttrium-aluminum-garnet phosphors activated with cerium, and lutetium-aluminum-garnet phosphors activated with cerium. Other examples include nitrogen-containing calcium aluminosilicate phosphors activated with europium and / or chromium, silicate phosphors activated with europium, β-SiAlON phosphors, nitride phosphors such as CASN or SCASN, and LnSi3N 11 Rare earth nitride phosphors such as the LnSiAlON system, BaSi2O2N2:Eu system, or Ba3Si6O 12N2:Eu-based oxynitride phosphors, CaS-based, SrGa2S4-based, ZnS-based sulfide phosphors, chlorosilicate phosphors, SrLiAl3N4:Eu phosphors, SrMg3SiN4:Eu phosphors, K2SiF6:Mn phosphors as manganese-activated fluoride complex phosphors, KSAF-based phosphors (e.g., K2Si 0.99 Al 0.01 F 5.99 You can use things like :Mn).

[0155] In a light-emitting device, the wavelength conversion member containing the light-emitting material may be, for example, a sheet or plate-shaped member, or a member having a three-dimensional shape. An example of a member having a three-dimensional shape is a sealing member formed by filling a recess with resin in order to seal a semiconductor light-emitting element when the semiconductor light-emitting element is placed on the bottom surface of a recess formed in a package of a surface-mount type light-emitting diode.

[0156] Alternatively, another example of a wavelength conversion member is a resin member formed to surround the top and side surfaces of a semiconductor light-emitting element with a substantially uniform thickness when the semiconductor light-emitting element is arranged on a planar substrate. Or, yet another example of a wavelength conversion member is a resin member formed in a flat plate shape with a predetermined thickness on top of the semiconductor light-emitting element and the resin member containing the reflective material when a resin member containing a reflective material is filled around the semiconductor light-emitting element such that its upper end is in the same plane as the semiconductor light-emitting element.

[0157] The wavelength conversion member may be in contact with the semiconductor light-emitting element, or it may be provided away from the semiconductor light-emitting element. Specifically, the wavelength conversion member may be a pellet-shaped member, sheet-shaped member, plate-shaped member, or rod-shaped member provided away from the semiconductor light-emitting element, or it may be a member provided in contact with the semiconductor light-emitting element, for example, a sealing member, a coating member (a member that covers the light-emitting element and is provided separately from the molded member), or a molded member (for example, a member having a lens shape).

[0158] Furthermore, in a light-emitting device, if two or more light-emitting materials that emit light at different wavelengths are used, the two or more light-emitting materials may be mixed within a single wavelength conversion member, or two or more wavelength conversion members containing only one type of light-emitting material may be used in combination. In this case, the two or more wavelength conversion members may form a laminated structure, or they may be arranged on a plane as a dot-like or stripe-like pattern.

[0159] An example of a semiconductor light-emitting element is an LED chip. The LED chip may have a semiconductor layer made of one or more materials selected from the group consisting of GaN, GaAs, InGaN, AlInGaP, GaP, SiC, and ZnO. A semiconductor light-emitting element that emits blue-violet light, blue light, or ultraviolet light may have a composition such as In X Al Y Ga 1-X-Y One example is a semiconductor layer comprising a GaN-based compound represented by N(0≦X, 0≦Y, X+Y<1).

[0160] The light-emitting device of this embodiment is preferably incorporated into a liquid crystal display device as a light source. Since band-edge emission by semiconductor nanoparticles has a short emission lifetime, a light-emitting device using a light-emitting material containing these nanoparticles is suitable as a light source for a liquid crystal display device that requires a relatively fast response speed. Furthermore, the light-emitting material of this embodiment can exhibit an emission peak with a small half-width as band-edge emission. Therefore, in the light-emitting device, blue light with a peak wavelength in the range of 420 nm to 490 nm is obtained by a blue semiconductor light-emitting element, and green light with a peak wavelength in the range of 510 nm to 550 nm, preferably 530 nm to 540 nm, and red light with a peak wavelength in the range of 600 nm to 680 nm, preferably 630 nm to 650 nm, is obtained by the light-emitting material. Furthermore, in the light-emitting device, by using a semiconductor light-emitting element to obtain ultraviolet light with a peak wavelength of 400 nm or less, and by using a light-emitting material to obtain blue light with a peak wavelength in the range of 430 nm to 470 nm, preferably 440 nm to 460 nm, green light with a peak wavelength in the range of 510 nm to 550 nm, preferably 530 nm to 540 nm, and red light with a peak wavelength in the range of 600 nm to 680 nm, preferably 630 nm to 650 nm, a liquid crystal display device with good color reproduction can be obtained without using a dark color filter. The light-emitting device can be used, for example, as a direct-type backlight or as an edge-type backlight. Alternatively, a sheet, plate-shaped member, or rod made of resin or glass, etc., containing a light-emitting material may be incorporated into the liquid crystal display device as a wavelength conversion member independent of the light-emitting device.

[0161] Herein, an example of a light-emitting device will be described with reference to the drawings. Figure 1 is a schematic cross-sectional view of the light-emitting device 100. The light-emitting device 100 comprises a substrate 1, a plurality of light source units 10 mounted on the substrate 1, and a wavelength conversion member 110. The substrate 1 is a circuit board for mounting and electrically connecting the plurality of light source units 10. The substrate 1 has a wiring layer formed on the substrate, and an insulating member is provided so that the mounting portion of the wiring layer is exposed. The plurality of light source units 10 are arranged in a matrix on the substrate 1 and irradiate the wavelength conversion member 110 in a planar manner. The wavelength conversion member 110 contains a light-emitting material including the semiconductor nanoparticles described above. In the light-emitting device 100, a portion of the light emitted from the light source units 10 is wavelength-converted by the light-emitting material contained in the wavelength conversion member 110, and is emitted as a mixed color of the light from the light source units 10 and the wavelength-converted light. [Examples]

[0162] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0163] Synthesis Example 1: Synthesis of 1,2-diamine compounds <Synthesis of (1S,2S)-N,N'-bis(salicylidene)-1,2-dodecanylethylenediamine>

[0164] [ka]

[0165] 4.12 g (20.8 mmol) of tridecanal and 2.44 g (9.99 mmol) of (1S,2S)-1,2-bis(2-hydroxyphenyl)ethylenediamine were weighed into a 50 ml round-bottom flask. 31 ml of toluene was added, and the mixture was refluxed in a Dean-Stark apparatus for 21 hours, after which the solvent was removed by distillation. The mixture was purified by silica gel column chromatography (cyclohexane:dichloromethane 3:2) to obtain 3.75 g of (1S,2S)-N,N'-bis(salicylidene)-1,2-dodecanylethylenediamine.

[0166] <Synthesis of (1R,2R)-1,2-didodecylethylenediamine>

[0167] [ka]

[0168] 3.75 g of (1S,2S)-N,N'-bis(salicylidene)-1,2-dodecanylethylenediamine was dissolved in 26 ml of tetrahydrofuran and 1.9 ml of 36% hydrochloric acid, and the mixture was stirred at 25°C for 24 hours. The mixture was cooled in an ice bath, and the precipitate was washed with tetrahydrofuran to obtain 2.07 g of crystals. 1.39 g of the obtained crystals was mixed with 25 ml of 1 M sodium hydroxide aqueous solution and stirred at 100°C for 1 hour. The organic layer was extracted with dichloromethane, dried over anhydrous sodium sulfate, and the solvent was removed by distillation to obtain 1.17 g of (1R,2R)-1,2-didodecylethylenediamine. The structure of the synthesized 1,2-diamine was confirmed by NMR. The results are shown below.

[0169] 1 H-NMR (600MHz, CDCl3): δ(ppm)2.53(2H,m),1.43(4H,m),1.34~1.21(40H,m),1.18(4H,s),0.88(6H,t,J=7.0Hz) 13 C-NMR (150MHz, CDCl3): δ(ppm)55.25,34.96,31.94,29.85,29.70,29.69,29.67,29.38,26.62,22.71,14.14

[0170] Synthesis Example 2: Synthesis of 1,3-diamine compounds <Synthesis of 2,2-didodecylpropanedinitrile>

[0171] [ka]

[0172] 0.37 g of lithium hydride was weighed into a 100 ml three-necked flask, and 31 ml of tetrahydrofuran was added. The mixture was cooled in an ice bath, and a solution of 1.22 g of malononitrile dissolved in 6 ml of tetrahydrofuran was added dropwise. After stirring at room temperature for 15 minutes, a solution of 9.00 g of 1-bromodecane dissolved in 6 ml of tetrahydrofuran was added dropwise. After refluxing for 24 hours, the mixture was cooled to room temperature, and 45 ml of water was added. The organic layer was extracted with diethyl ether, washed with water, dried over Na2SO4, and the solvent was removed by distillation. The mixture was purified by silica gel column chromatography (hexane-dichloromethane) to obtain 6.33 g of 2,2-didodecylpropanedinitrile.

[0173] <Synthesis of 2,2-didodecyl-1,3-propanediamine>

[0174] [ka]

[0175] 1.06 g of lithium aluminum hydride was weighed into a 100 ml three-necked flask, and 30 ml of diethyl ether was added. The mixture was cooled in an ice bath, and a solution of 3.10 g of 2,2-didodecylpropanedinitrile dissolved in 10 ml of tetrahydrofuran was added dropwise. After stirring at room temperature for 20 hours, the mixture was cooled in an ice bath, and 2.2 ml of water was added dropwise. Further, 0.2 ml of 50% aqueous sodium hydroxide solution was added, the mixture was stirred at room temperature for 1 hour, and then filtered. 20 g of anhydrous sodium sulfate was added to the filtrate, the mixture was stirred overnight, and then filtered. The solvent was removed by distillation to obtain 2.73 g of 2,2-didodecyl-1,3-propanediamine. The structure of the synthesized 1,3-diamine was confirmed by NMR. The results are shown below.

[0176] 1 H-NMR (600MHz, CDCl3): δ(ppm)2.51(4H,s),1.34~1.20(30H,m),1.20-1.12(6H,m),1.09(4H,br s),0.88(6H,t,J=7.1Hz) 13C-NMR (150MHz, CDCl3): δ(ppm)46.12,40.38,32.52,31.93,30.67,29.72,29.69,29.66,29.37,22.91,22.70,14.13

[0177] Synthesis Example 3: Synthesis of 1,4-diamine compounds <Synthesis of 11,14-tetracosandione>

[0178] [ka]

[0179] 3.20 g of magnesium powder was weighed into a 300 ml round-bottom flask, and 70 ml of tetrahydrofuran was added. 26.98 g of 1-bromodecane was added dropwise, and the mixture was stirred at room temperature for 30 minutes and then at 60°C for 30 minutes. After cooling to room temperature, 100 ml of tetrahydrofuran was added to dissolve the precipitate, and the mixture was filtered to obtain an n-decylmagnesium bromide solution.

[0180] 16.80 g of copper(I) bromide was weighed into a 1 L four-necked flask, and 60 ml of tetrahydrofuran was added. A solution of 20.34 g of lithium bromide dissolved in 70 ml of tetrahydrofuran was added dropwise at room temperature. The mixture was cooled to -100 to -80°C, and n-decylmagnesium bromide solution was added dropwise, stirring for 30 minutes. 7.56 g of succinyl chloride was added dropwise, and the mixture was stirred overnight while raising the temperature to room temperature. 100 ml of saturated ammonium chloride aqueous solution was added, filtered, and washed with water. The residue was dried and recrystallized from tetrahydrofuran-ethyl acetate to obtain 9.84 g of 11,14-tetracosanedione.

[0181] <Synthesis of 11,14-tetracosanediol>

[0182] [ka]

[0183] 1.24 g of lithium aluminum hydride was weighed into a 200 ml three-necked flask, and 20 ml of tetrahydrofuran was added. The mixture was cooled in an ice bath, and a solution of 3.00 g of 11,14-tetracosanedione dissolved in 85 ml of tetrahydrofuran was added dropwise. After stirring at room temperature for 15 hours, the mixture was reduced in pressure, and 50 ml of tetrahydrofuran was removed by distillation. The mixture was cooled in an ice bath, and 4 ml of saturated sodium sulfate aqueous solution was added. Extraction with diethyl ether yielded 2.88 g of 11,14-tetracosanediol.

[0184] <Synthesis of 11,14-bis(p-toluenesulfonyloxy)tetracosane>

[0185] [ka]

[0186] 5.63 g of p-toluenesulfonic anhydride was weighed into a 200 ml three-necked flask, and 7 ml of tetrahydrofuran was added. The mixture was cooled in an ice bath, and 2.75 g of pyridine was added dropwise, followed by the addition of a solution of 1.59 g of 11,14-tetracosanediol dissolved in 75 ml of tetrahydrofuran. After stirring at room temperature for 16 hours, the mixture was concentrated under reduced pressure. 20 ml of ice water was added, and the mixture was extracted with diethyl ether. After drying over anhydrous magnesium sulfate, the solvent was removed by distillation. The mixture was purified by silica gel column chromatography (chloroform:hexane 2:1) to obtain 2.69 g of 11,14-bis(p-toluenesulfonyloxy)tetracosane.

[0187] <Synthesis of 11,14-diphthaloylaminotetracosan>

[0188] [ka]

[0189] 2.51 g of 11,14-bis(p-toluenesulfonyloxy)tetracosan and 1.71 g of potassium phthalimide were weighed into a 100 ml three-necked flask, and 12.5 ml of N,N-dimethylformamide was added. After stirring at 90°C for 4 hours, 40 ml of ice water was added. 85 ml of water was added, and the mixture was extracted with diethyl ether and dried over anhydrous magnesium sulfate. After removing the solvent by distillation, the residue was washed with hexane to obtain 1.05 g of 11,14-diphthaloylaminotetracosan.

[0190] <Synthesis of 11,14-tetracosanediamine>

[0191] [ka]

[0192] 0.36 g of 11,14-diphthaloylaminotetracosane and 0.12 g of hydrazine monohydrate were weighed into a 50 ml three-necked flask, and 4.5 ml of ethanol was added. After stirring at 90°C for 10 hours, the mixture was filtered and washed with ethanol. The residue was extracted with a mixed solvent of 9 ml of chloroform and 6 ml of hexane, and the solvent was removed by distillation to obtain 0.21 g of 11,14-tetracosanediamine. The structure of the synthesized 1,4-diamine was confirmed by NMR. The results are shown below.

[0193] 1 H-NMR(600MHz,CD3OD):δ(ppm)2.72(2H,m),1.59-1.13(40H,m),0.89(6H,t,J=7.1Hz) 13 C-NMR(150MHz,CD3OD):δ(ppm)52.52,37.76,33.95,33.11,30.90,30.80,30.74,30.52,26.95,23.78,14.56

[0194] Synthesis Example 4: Synthesis of 1,4-diamine compounds <Synthesis of 7,10-hexadecanedione>

[0195] [ka]

[0196] 4.03 g of magnesium powder was weighed into a 300 ml round-bottom flask, and 50 ml of tetrahydrofuran was added. A solution of 25.33 g of 1-bromohexane dissolved in 20 ml of tetrahydrofuran was added dropwise, and the mixture was stirred at room temperature for 30 minutes and then at 60°C for 30 minutes. After cooling to room temperature, 130 ml of tetrahydrofuran was added to dissolve the precipitate, and the mixture was filtered to obtain an n-hexylmagnesium bromide solution.

[0197] 21.13 g of copper(I) bromide was weighed into a 1 L four-necked flask, and 75 ml of tetrahydrofuran was added. A solution of 25.59 g of lithium bromide dissolved in 100 ml of tetrahydrofuran at room temperature was added dropwise. The mixture was cooled to -100 to -80 °C, and n-hexylmagnesium bromide solution was added dropwise, stirring for 30 minutes. 9.51 g of succinyl chloride was added dropwise, and the mixture was stirred overnight while raising the temperature to room temperature. The pressure was reduced, and 230 ml of tetrahydrofuran was removed by distillation. Then, 150 ml of saturated ammonium chloride aqueous solution was added, the mixture was filtered, and washed with water. The residue was dried, and recrystallized from tetrahydrofuran-ethyl acetate to obtain 10.71 g of 7,10-hexadecanedione.

[0198] <Synthesis of 7,10-hexadecanediol>

[0199] [ka]

[0200] 6.19 g of lithium aluminum hydride was weighed into a 500 ml three-necked flask, and 60 ml of tetrahydrofuran was added. The mixture was cooled in an ice bath, and a solution of 10.40 g of 7,10-hexadecanedione dissolved in 90 ml of tetrahydrofuran was added dropwise. After stirring at room temperature for 40 hours, the mixture was cooled in an ice bath, and 20 ml of saturated sodium sulfate aqueous solution and 70 ml of diethyl ether were added. After stirring at room temperature for 1 hour, the mixture was filtered, and the filtrate and washings were concentrated to dryness to obtain 8.76 g of 7,10-hexadecanediol.

[0201] <Synthesis of 7,10-bis(p-toluenesulfonyloxy)hexadecane>

[0202] [ka]

[0203] 32.73 g of p-toluenesulfonic anhydride was weighed into a 500 ml three-necked flask, and 86 ml of tetrahydrofuran was added. The mixture was cooled in an ice bath, and 15.87 g of pyridine was added dropwise, followed by the addition of a solution of 6.48 g of 7,10-hexadecanediol dissolved in 172 ml of tetrahydrofuran. After stirring at room temperature for 16 hours, the mixture was concentrated under reduced pressure. 120 ml of water was added, and the mixture was extracted with diethyl ether. After drying over anhydrous magnesium sulfate, the solvent was removed by distillation. Recrystallization from diethyl ether-hexane yielded 13.82 g of 7,10-bis(p-toluenesulfonyloxy)hexadecane.

[0204] <Synthesis of 7,10-diphthaloylaminohexadecane>

[0205] [ka]

[0206] 6.00 g of 7,10-bis(p-toluenesulfonyloxy)hexadecane and 4.90 g of potassium phthalimide were weighed into a 100 ml three-necked flask, and 36 ml of N,N-dimethylformamide was added. After stirring at 90°C for 4 hours, 65 ml of ice water was added, the mixture was filtered, and washed with 70 ml of water. The residue was washed with 60 ml of methanol, and then purified by silica gel column chromatography (chloroform) to obtain 2.44 g of 7,10-diphthaloylaminohexadecane.

[0207] <Synthesis of 7,10-hexadecanediamine>

[0208] [ka]

[0209] 0.25 g of 7,10-diphthaloylaminohexadecane and 0.096 g of hydrazine monohydrate were weighed into a 50 ml three-necked flask, and 3.5 ml of ethanol was added. After stirring at 90°C for 9 hours, 3 ml of water and concentrated hydrochloric acid were added to adjust the pH to 3. Insoluble matter was filtered off and washed with water. The filtrate and washings were concentrated, 5 ml of 40% sodium hydroxide aqueous solution was added, and the mixture was extracted with 2-methyltetrahydrofuran and washed with saturated sodium chloride aqueous solution. After drying over anhydrous sodium sulfate, the mixture was filtered, and the solvent was removed by distillation to obtain 0.12 g of 7,10-hexadecanediamine. The structure of the synthesized 1,4-diamine was confirmed by NMR. The results are shown below.

[0210] 1 H-NMR (400MHz, CDCl3): δ(ppm)2.68(2H,s),1.57-1.17(24H,m),0.88(6H,t,J=6.9Hz) 13 C-NMR (100MHz, CDCl3): δ(ppm)51.49,51.47,38.25,38.11,34.62,34.60,31.87,30.32,29.48,26.17,26.11,22.65,14.10

[0211] Preparation of semiconductor nanoparticle dispersion A chloroform dispersion of semiconductor nanoparticles with oleylamine arranged on their surface was obtained with reference to the description in Example 5 of Japanese Patent Publication No. 2018-39971.

[0212] Example 1 The chloroform dispersion of semiconductor nanoparticles with oleylamine on their surface, prepared as described above, was diluted with chloroform to adjust the concentration so that the absorbance at 450 nm was 4.76. 600 μl of this dispersion was then mixed with 0.49 mmol of the 1,2-diamine compound obtained in Synthesis Example 1. The mixture was stirred under a nitrogen atmosphere at 25°C for 20 hours to obtain a chloroform dispersion of semiconductor nanoparticles with the 1,2-diamine compound (ligand) on their surface.

[0213] Under a nitrogen atmosphere, 100 μl of the chloroform dispersion of the semiconductor nanoparticles obtained above was transferred to a centrifuge tube and concentrated by blowing nitrogen gas onto it. After adding 100 μl of ethanol and shaking, the mixture was centrifuged and the supernatant was removed. The remaining precipitate was dispersed in 10 μl of chloroform, 100 μl of ethanol was added and shaken, then the mixture was centrifuged and the supernatant was removed. This washing process was repeated twice, and the remaining precipitate was dispersed in chloroform to obtain chloroform dispersion E1 of ligand-substituted and washed semiconductor nanoparticles, which are the luminescent material.

[0214] Examples 2 to 4 Chloroform dispersions E2 to E4 of ligand-substituted and washed semiconductor nanoparticles (luminescent materials) from Examples 2 to 4 were obtained in the same manner as in Example 1, except that the diamine compounds obtained in Synthesis Examples 2 to 4 were used instead of the 1,2-diamine compound obtained in Synthesis Example 1.

[0215] Comparative Example 1 A chloroform dispersion C1 of ligand-substituted and washed semiconductor nanoparticles for Comparative Example 1 was obtained in the same manner as in Example 1, except that decylamine was used instead of the 1,2-diamine compound obtained in Synthesis Example 1.

[0216] Measurement of luminescence quantum efficiency The emission spectra of the chloroform dispersions of the ligand-substituted and washed semiconductor nanoparticles obtained above were measured, and the internal quantum efficiency was calculated and declared as the emission quantum efficiency after ligand substitution and washing. The emission spectra were measured using a quantum efficiency measurement system (Otsuka Electronics Co., Ltd., product name QE-2100) at room temperature (25°C) with an excitation light wavelength of 450 nm, in the wavelength range of 300 nm to 950 nm, and the internal quantum efficiency was calculated from the wavelength range of 500 nm to 950 nm. Furthermore, the emission quantum efficiency before ligand substitution was measured in the same manner as above for the chloroform dispersions of semiconductor nanoparticles with oleylamine arranged on the surface used in Examples 1 to 4 and Comparative Example 1, respectively.

[0217] Luminescence quantum efficiency retention rate Table 1 shows the results of determining the luminescence quantum efficiency retention rate for the chloroform dispersions of ligand-substituted and washed semiconductor nanoparticles obtained in Examples 1 to 4 and Comparative Example 1, using the following formula.

[0218]

number

[0219] [Table 1]

[0220] Table 1 shows that the binding of ligands to semiconductor nanoparticles is strongest in the order of 1,4-diamine, 1,3-diamine, 1,2-diamine, and monoamine. [Explanation of symbols]

[0221] 1 circuit board 10 Light source section 100 Light-emitting devices 110 Wavelength conversion component

Claims

1. A light-emitting material comprising semiconductor nanoparticles comprising a first semiconductor comprising a group 11 element containing Ag and possibly Cu, a group 13 element containing at least one of In and Ga, and a group 16 element containing S, A second semiconductor, comprising at least Ga and S, is disposed on the surface of the aforementioned semiconductor nanoparticles. A light-emitting material wherein a diamine compound having a structure represented by any of the following formulas (1a) to (1g) is disposed on the surface of the second semiconductor. 【Chemistry 1】 (In the formula, R1 independently represents an optionally substituted alkyl group having 6 to 12 carbon atoms.)

2. The first semiconductor is the light-emitting material according to claim 1, having a chalcopyrite structure.

3. The second semiconductor is the light-emitting material according to claim 1 or 2, comprising gallium sulfide.

4. The light-emitting material according to any one of claims 1 to 3, wherein the diamine compound is represented by formula (1a) or (1d).

5. The light-emitting material according to any one of claims 1 to 3, wherein the diamine compound is represented by any one of formulas (1d) to (1g).

6. The light-emitting material according to any one of claims 1 to 5, wherein the semiconductor nanoparticles emit light having a longer wavelength than the irradiated light when irradiated with light having a wavelength in the range of 350 nm or more and less than 500 nm.

7. The semiconductor nanoparticles emit light having a full width at half maximum of 70 nm or less in the emission spectrum, according to any one of claims 1 to 6.

8. A light-emitting device comprising a wavelength conversion member containing a light-emitting material according to any one of claims 1 to 7, and a light-emitting element.

9. The light-emitting device according to claim 8, wherein the light-emitting element is a light-emitting diode.

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