Semiconductor particles and electronic devices

Abstract

To provide semiconductor particles capable of achieving a light-emitting electronic device having a good chromatic purity of blue light emission, a high light emission efficiency and a long service life, and to provide an electronic device using the semiconductor particles.SOLUTION: Semiconductor particles include a semiconductor containing gallium, nitrogen, and indium or aluminum, and have an average particle diameter of 1-1,000 nm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to semiconductor particles and electronic devices. [Background technology]

[0002] Recent advancements in organic light-emitting diode (OLED) and OLED display device technology have been remarkable, but several problems remain unresolved in the development of inexpensive liquid crystal displays. Among these, the problems with organic light-emitting materials used in OLED displays include issues with the color purity of blue light-emitting materials, luminous efficiency, luminous lifetime, and the need to address coating technology.

[0003] In fact, several proposals have been made to solve these problems. The first is an attempt to improve luminescence efficiency using phosphorescent materials or delayed fluorescence materials. Both phosphorescent and delayed fluorescence materials have succeeded in increasing luminescence efficiency by utilizing the energy of the triplet level (Patent Documents 1-2, Non-Patent Documents 1-2), but in the case of blue light-emitting materials, the emission wavelength range extends to the longer wavelength side, so there are problems with color purity and the emission lifetime is short (1,000 cd / m²). 2 At its initial brightness, the battery life (half-life is only a few hours) is still not suitable for display applications.

[0004] The second approach involves using inorganic semiconductor particles with light-emitting properties as the active layer. As blue light-emitting materials, those mainly composed of cadmium sulfide, zinc sulfide, and zinc selenide have been attempted (Non-Patent Literature 3). While the emission wavelength range is sharper and the color purity is good compared to phosphorescent and delayed fluorescence materials, the problem of a very short emission lifetime remains.

[0005] The third issue is addressing coating technology using polymer materials. Even with polymer coating materials, blue light-emitting materials have problems with both luminous efficiency and luminous lifetime, making them unsuitable for display applications.

[0006] On the other hand, while a wide range of research and development related to renewable energy has been conducted in recent years, solar cell devices that can be manufactured using simple and low-cost coating processes have not yet reached a practical level.

[0007] While silicon single crystals and III-V compound single crystal devices can realize highly efficient and long-life solar cell devices (Non-Patent Literature 4), the manufacturing process involves high-temperature epitaxial growth on single crystal substrates, making it very expensive. To enable a simple coating process on inexpensive substrates such as glass, a low-temperature process mainly using polymer materials is necessary, but the power generation efficiency and durability are far from practical levels (Non-Patent Literature 5).

[0008] In recent years, coating materials using III-V nanoparticles have been proposed for solar cells, and high power generation efficiency is expected, but highly durable materials have not yet been proposed (Non-Patent Literature 6). [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Special Publication No. 2004-506305 [Patent Document 2] Japanese Patent Publication No. 2004-199875 [Patent Document 3] Japanese Patent Publication No. 2016-197601 [Non-patent literature]

[0010] [Non-Patent Document 1] M. Groarke et.al. J Soc Inf Disp. 2012, Vol.20(1), p.70-78 [Non-Patent Document 2] T. Miwa et.al. Sci. Rep. 2017, Vol.7, Article number: 284 [Non-Patent Document 3] Y. Yang et. al. Nat. Photon. 2015, Vol.9(4), p.259-266 [Non-Patent Document 4] NEDO Renewable Energy Technology White Paper, 2nd Edition (2014), Morikita Publishing [Non-Patent Document 5] Y. Zhang et.al. Advanced Science. 2018, Vol.5, p.1800434 [Non-Patent Document 6] O. E. Semonin et. al. Science. 2011, Vol.334, 1530 [Summary of the Invention] [Problems to be Solved by the Invention]

[0011] [[ID=​​​​​​​​​​​​​​​​​​Containing a semiconductor comprising gallium, nitrogen, and indium or aluminum, having an average particle diameter of 1 to 1000 nm, semiconductor particles. 〔2〕 where the semiconductor is represented by the following compositional formula (1): X a Ga b N C (In the formula, X represents indium or aluminum, and a, b, and c satisfy 0.7 ≤ a + b ≤ 1.5, 0.01 ≤ a ≤ 0.5, 0.2 ≤ b ≤ 1.49, and 0.8 ≤ c ≤ 1.2.) represented by the semiconductor particles according to 〔1〕. 〔3〕 where the semiconductor is represented by the following compositional formula (2): X a Ga b N C (In the formula, X represents indium or aluminum, and a, b, and c satisfy a + b = 1.0, 0.01 ≤ a ≤ 0.5, and c = 1.) represented by the semiconductor particles according to 〔1〕. 〔4〕 having a LUMO level of less than -2.0 eV, and a band gap of 2.0 eV or more, the semiconductor particles according to any one of 〔1〕 to 〔3〕. 〔5〕 having polar molecules on the surface, the semiconductor particles according to any one of 〔1〕 to 〔4〕. 〔6〕 an organic solvent, and the semiconductor particles according to any one of 〔1〕 to 〔5〕 dispersed in the organic solvent, a semiconductor particle dispersion liquid. 〔7〕 a dispersion step of obtaining a dispersion liquid by dispersing a powder containing gallium, a nitrogen raw material, and a powder containing indium or a powder containing aluminum in an organic solvent, The method includes an irradiation step of irradiating the dispersion with light to obtain semiconductor particles containing a semiconductor comprising gallium, nitrogen, and indium or aluminum. A method for manufacturing semiconductor particles. [8] In the irradiation step, The powder in the dispersion is irradiated with laser light to obtain the semiconductor particles. A method for producing semiconductor particles as described in [7]. [9] In the irradiation step, The semiconductor particles are obtained by individually or alternately irradiating the powder in the dispersion with light of a single wavelength or light of multiple wavelengths. A method for producing semiconductor particles as described in [7] or [8].

[10] The dispersion contains dissolved nitrogen, A method for producing semiconductor particles as described in any one of items [7] to [9].

[11] The dispersion contains polar molecules, A method for producing semiconductor particles as described in any one of items [7] to

[10] .

[12] The dispersion contains an amino group-containing compound. A method for manufacturing semiconductor particles as described in any one of items [7] to

[11] .

[13] The process includes flowing a gas containing nitrogen into the dispersion. A method for producing semiconductor particles as described in any one of items [7] to

[12] .

[14] It includes a cathode, an anode, and an active layer disposed between the cathode and the anode, The active layer comprises semiconductor particles as described in any one of items [1] to [5], Electronic devices.

[15] The active layer contains 25% or more by volume of the semiconductor particles. The electronic device described in

[14] .

[16] The active layer comprises 0.1 to 20 volume percent of the semiconductor particles and 50 volume percent or more of the organic host material. The electronic device described in

[14] .

[17] Between the cathode or anode and the active layer, there is an electron transport layer or a hole transport layer. An electronic device as described in any one of items

[14] to

[16] .

[18] It is a light-emitting device that emits light with a peak wavelength of 500 nm or less. An electronic device as described in any one of items

[14] to

[17] .

[19] It is a light-powered device that absorbs light and generates electricity. An electronic device as described in any one of items

[14] to

[16] . [Effects of the Invention]

[0015] According to the present invention, it is possible to provide semiconductor particles that can realize a light-emitting device with good color purity of blue light emission, high luminous efficiency, and long lifespan, or a photovoltaic electronic device with high efficiency and long lifespan, and an electronic device using said semiconductor particles. [Brief explanation of the drawing]

[0016] [Figure 1] This figure shows an example of the layer configuration of an electronic device according to this embodiment. [Figure 2] This is a transmission electron microscope image of semiconductor particles contained in the transparent solution obtained in Example 1. [Figure 3] This is a photograph showing the luminescence of a semiconductor particle dispersion according to this embodiment. [Figure 4] This figure shows the emission spectrum of the semiconductor particle dispersion according to this embodiment. [Figure 5] This figure shows the layer configuration of the light-emitting device fabricated in Example 2. [Figure 6] This figure shows the voltage-current characteristics and voltage-luminance characteristics of the light-emitting device fabricated in Example 2. [Figure 7]It is a diagram showing the emission spectrum of the light-emitting device fabricated in Example 2. [Figure 8] It is a table showing the basic characteristics of the light-emitting device fabricated in Example 2.

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. However, the present invention is not limited thereto, and various modifications are possible without departing from the gist thereof.

[0018] 〔Semiconductor Particles〕 The semiconductor particles of the present embodiment contain a semiconductor containing gallium, nitrogen, and indium or aluminum, and are characterized in that the average particle diameter is 1 to 1000 nm.

[0019] The semiconductor contained in the semiconductor particles of the present embodiment is not particularly limited as long as it contains gallium, nitrogen, and indium or aluminum. For example, those represented by the following compositional formula (1) are preferable. By using semiconductor particles containing such a semiconductor, the color purity, luminous efficiency, and luminous lifetime of blue light emission tend to be further improved. X a Ga b N C ···(1) (In the formula, X represents indium or aluminum, and a, b, and c satisfy 0.7 ≤ a + b ≤ 1.5, 0.01 ≤ a ≤ 0.5, 0.2 ≤ b ≤ 1.49, and 0.8 ≤ c ≤ 1.2.)

[0020] In the formula, a indicates the ratio of indium (In) or aluminum (Al). From the viewpoints of the color purity, luminous efficiency, and luminous lifetime of blue light emission, a is preferably 0.01 to 0.5, more preferably 0.03 to

[0021] In the formula, b represents the proportion of gallium (Ga). From the viewpoint of color purity, luminous efficiency, and luminescence lifetime of blue emission, b is preferably 0.2 to 1.49, more preferably 0.4 to 1.3, and even more preferably 0.6 to 1.1.

[0022] In the formula, c represents the proportion of nitrogen (N). From the viewpoint of color purity, luminous efficiency, and luminescence lifetime of blue emission, c is preferably 0.8 to 1.2, more preferably 0.9 to 1.1, and even more preferably 1.

[0023] From the viewpoint of color purity, luminous efficiency, and luminescence lifetime of blue light emission, the sum of a and b is preferably 0.7 to 1.5, more preferably 0.8 to 1.3, even more preferably 0.9 to 1.1, and particularly preferably 1.

[0024] Among the above, semiconductor particles represented by the following compositional formula (2) are preferred. Using such semiconductor particles tends to further improve the color purity, luminous efficiency, and luminous lifetime of blue light emission. X a Ga b N C ...(2) (In the formula, X represents indium or aluminum, and a, b, and c satisfy a+b=1.0, 0.01≦a≦0.5, and c=1.)

[0025] Furthermore, the semiconductor particles of this embodiment include not only those composed of semiconductor particles containing gallium, nitrogen, and indium or aluminum, but also semiconductor particles having a core-shell structure, wherein the core contains the semiconductor containing gallium, nitrogen, and indium or aluminum, or the shell contains the semiconductor containing gallium, nitrogen, and indium or aluminum.

[0026] Furthermore, as semiconductors other than the above semiconductors containing gallium, nitrogen, and indium or aluminum, the semiconductors included in the core or shell of the semiconductor particles of this embodiment are not particularly limited, but examples include semiconductors using group II-VI elements such as CdSe, CdS, CdTe, ZnSe, ZnO, ZnS, ZnTe, HgS, HgSe, and HgTe; semiconductors using group III-V elements such as InAs, InP, GaAs, GaP, InN, GaN, InSb, GaSb, AlP, AlAs, and AlSb; semiconductors using group IV-VI elements such as PbSe, PbTe, and PbS; semiconductors using group III-VI elements such as InSe, InTe, InS, and GaSe; and semiconductors using group IV elements such as Si and Ge.

[0027] The average particle diameter of the semiconductor particles is 1 to 1000 nm, preferably 2 to 500 nm, more preferably 50 to 400 nm, even more preferably 100 to 300 nm, and particularly preferably 100 to 200 nm. The larger the average particle diameter of the semiconductor particles, the longer the emission wavelength of the light-emitting device using the semiconductor particles tends to be, and the smaller the average particle diameter of the semiconductor particles, the shorter the emission wavelength tends to be. Furthermore, the semiconductor particles of this embodiment, having an average particle diameter within the above range, tend to have improved blue color purity. The average particle diameter can be measured by the method described in the examples. Note that semiconductor particles with an average particle diameter within a specific range can also be called "quantum dots".

[0028] Furthermore, a narrow emission spectrum approaches a specific monochromatic light, resulting in higher color purity. Conversely, a wide emission spectrum mixes various colors (wavelengths), tending to lower color purity. From this perspective, monodisperse semiconductor particles are preferable.

[0029] The LUMO level of the semiconductor particle is preferably less than -2.0 eV, more preferably less than -2.8 eV, and even more preferably less than -3.0 eV. The lower limit of the LUMO level is not particularly limited, but is preferably -4.0 eV or higher. A LUMO level of less than -2.0 eV tends to improve luminous efficiency and extend the luminescence lifetime.

[0030] The HOMO level of the semiconductor particle is preferably -6.5 eV or higher, and more preferably -6.0 eV or higher. There is no particular upper limit to the HOMO level, but it is preferably -5.5 eV or lower. A HOMO level of -6.5 eV or higher tends to improve luminescence efficiency.

[0031] The band gap of the semiconductor particles is preferably 2.0 eV or higher, more preferably 2.7 eV or higher, and even more preferably 2.8 eV or higher. A band gap of -2.0 eV or higher tends to result in shorter wavelength emission colors.

[0032] In this embodiment, the orbital energies (HOMO and LUMO) can be measured by photoelectron spectroscopy, and the band gap can be measured by absorption-emission spectroscopy.

[0033] The semiconductor particles preferably contain a semiconductor having the above composition and have polar molecules on at least a portion of their surface. The attachment of polar molecules to at least a portion of the surface of the semiconductor particles tends to improve the dispersibility of the semiconductor particles in solutions and polymers, as well as the color purity, luminescence efficiency, and luminescence lifetime of the semiconductor particles when dispersed in them.

[0034] The polar molecules are not particularly limited, but examples include molecules having an anchor group bonded to the semiconductor particle surface by covalent or coordinate bonding, an organic functional group having a relatively high HOMO level, and a spacer group linking the anchor group and the organic functional group. Here, the anchor group is not particularly limited, but examples include a thiol group, and the organic functional group is not particularly limited, but examples include groups containing amines, triarylamines, thiophenes, carbazoles, phthalocyanines, or porphyrins. The spacer group is not particularly limited, but examples include alkyl groups.

[0035] [Semiconductor particle dispersion] The semiconductor particle dispersion of this embodiment comprises an organic solvent and the semiconductor particles dispersed in the organic solvent. By applying the semiconductor particle dispersion onto a substrate by spin coating or the like, a layer containing semiconductor particles can be easily formed.

[0036] The organic solvent is not particularly limited, but examples include alcoholic solvents such as isopropyl alcohol and aromatic solvents such as xylene.

[0037] The content of semiconductor particles in a semiconductor particle dispersion depends on the application of the semiconductor particle dispersion, but is preferably 0.1 to 50% by mass, more preferably 0.5 to 40% by mass, and even more preferably 1 to 30% by mass, relative to the total amount of the semiconductor particle dispersion. A semiconductor particle content within this range tends to improve dispersion stability. Furthermore, when used in applications such as spin coating, the semiconductor particle content in the semiconductor particle dispersion is preferably 0.1 to 5% by mass, more preferably 0.5 to 4% by mass, and even more preferably 1 to 3% by mass, relative to the total amount of the semiconductor particle dispersion. A semiconductor particle content within this range tends to improve coating properties.

[0038] The semiconductor particle dispersion may contain other components, which are not particularly limited, but include, for example, polar molecules, polymers, and surfactants.

[0039] [Method for manufacturing semiconductor particles] Conventionally, chemical methods such as the solution-phase colloid method are known as methods for manufacturing semiconductor particles composed of semiconductors. In this method, semiconductor nanocrystal nuclei are formed in a solution, and these nuclei are grown to obtain semiconductor particles. However, it is difficult to synthesize semiconductor particles containing gallium, nitrogen, and indium or aluminum using this method. Furthermore, the semiconductor particles obtained by the above methods exhibit rapid luminescence loss and instability, and based on their performance, it is difficult to say that they are properly synthesized semiconductors containing gallium, nitrogen, and indium or aluminum.

[0040] This embodiment relates to a novel synthesis method using liquid-phase laser ablation as a method for synthesizing semiconductor particles containing a semiconductor comprising gallium, nitrogen, and indium or aluminum. Specifically, the method for producing semiconductor particles according to this embodiment includes a dispersion step of obtaining a dispersion liquid by dispersing a gallium-containing powder, a nitrogen raw material, and an indium-containing powder or an aluminum-containing powder in an organic solvent, and an irradiation step of irradiating the dispersion liquid with light to obtain semiconductor particles containing a semiconductor comprising gallium, nitrogen, and indium or aluminum.

[0041] (Dispersion process) The dispersion process involves obtaining a dispersion liquid by dispersing a gallium-containing powder, a nitrogen raw material, and an indium-containing powder or an aluminum-containing powder in an organic solvent. The method for preparing the dispersion liquid is not particularly limited and includes methods such as adding and mixing each raw material in the organic solvent, high-speed stirring, bead milling, jet milling, and planetary milling.

[0042] Here, the organic solvent is not particularly limited, but examples include alcohol-based solvents such as isopropyl alcohol.

[0043] The gallium-containing powder is not particularly limited, but an example is gallium nitride powder. Similarly, the indium-containing powder is not particularly limited, but an example is indium nitride powder. Furthermore, the aluminum-containing powder is not particularly limited, but an example is aluminum nitride powder. The nitrogen raw material is not particularly limited, but examples include gallium nitride powder, indium nitride powder, aluminum nitride powder, etc. Note that the gallium-containing powder, nitrogen raw material, indium-containing powder, and aluminum-containing powder may be different compounds or the same compound. For example, since gallium nitride powder falls under both the category of gallium-containing powder and nitrogen raw material, using gallium nitride powder can be considered equivalent to using both gallium-containing powder and nitrogen raw material in the dispersion process. Among these, it is preferable to use gallium nitride powder and indium nitride powder in combination. Indium organic compounds and gallium organic compounds can also be used.

[0044] Furthermore, the dispersion may contain amino group-containing compounds such as ammonia, nitrogen-containing raw materials, or dissolved nitrogen, from the viewpoint of compensating for nitrogen defects in the semiconductor particles during the formation of semiconductor particles. When using dissolved nitrogen, it is conceivable to add nitrogen to the dispersion by blowing nitrogen gas into it. In addition, the dispersion may contain a solvent having an amino group as the amino group-containing compound, and dimethylformamide, pyridine, etc., can be used.

[0045] When gallium nitride powder and indium nitride powder are used in combination, the mass ratio can be adjusted according to the composition of the semiconductor constituting the semiconductor particles to be used. Furthermore, from the viewpoint of reaction efficiency, the total content of the gallium-containing powder, nitrogen raw material, and indium-containing powder or aluminum-containing powder is preferably 1 to 50% by mass, more preferably 3 to 40% by mass, and even more preferably 5 to 30% by mass, relative to the total amount of the dispersion.

[0046] In addition to the above, the dispersion may also contain polar molecules. There are no particular limitations on the polar molecules, but examples include those mentioned above.

[0047] (irradiation process) The irradiation process involves irradiating a powder in a dispersion with light to obtain semiconductor particles. The energy of the light irradiation causes a reaction between the gallium-containing powder, the nitrogen raw material, and the indium-containing or aluminum-containing powder, forming semiconductor particles. Examples of light sources include solid-state lasers such as YAG, semiconductor lasers such as GaAs and InGaAsP, and gaseous lasers such as KrF. Among these, solid-state lasers are preferred. Using such light tends to lead to more efficient synthesis of semiconductor particles.

[0048] Methods for inducing a plasma state by irradiating a solid target with high-density laser light in a solution to produce nanoparticles of the same material composition are known. Methods for granulating materials of the same composition by irradiating particles in a liquid with laser light are also known. However, the liquid-phase laser ablation method used in this embodiment is a method for synthesizing a new material by irradiating raw materials with laser light in a solution, thereby miniaturizing the material and simultaneously reacting it with a different material.

[0049] Furthermore, methods of light irradiation include continuous irradiation with single-wavelength light, continuous irradiation with multi-wavelength light, intermittent irradiation with single-wavelength light, intermittent irradiation with multi-wavelength light, alternating irradiation with single-wavelength light and multi-wavelength light, alternating irradiation with two or more single-wavelength lights of different wavelengths, and alternating irradiation with two or more multi-wavelength lights of different wavelengths. By using such methods, semiconductor particles tend to be synthesized more efficiently.

[0050] The wavelength of the irradiated light is preferably 150 to 1100 nm, more preferably 193 to 800 nm, and even more preferably 193 to 400 nm. By setting the wavelength within the above range, semiconductor particles tend to be synthesized more efficiently.

[0051] Furthermore, the pulse width of the irradiated laser can be femtosecond, picosecond, or nanosecond, preferably 5 to 300 ns, more preferably 10 to 100 ns, and even more preferably 10 to 50 ns. By setting the pulse width within the above range, semiconductor particles tend to be synthesized more efficiently.

[0052] Furthermore, the laser output per pulse is preferably 30 to 250 mJ, more preferably 40 to 200 mJ, and even more preferably 50 to 150 mJ. By setting the output within the above range, semiconductor particles tend to be synthesized more efficiently.

[0053] The irradiation time depends on the type of light used and the amount of dispersion being treated, but is preferably 0.25 to 3 hours, more preferably 0.5 to 2 hours, and even more preferably 0.75 to 1.5 hours. By setting the irradiation time within the above range, semiconductor particles tend to be synthesized more efficiently.

[0054] [Electronic Devices] The electronic device of this embodiment includes a cathode 1, an anode 2, and an active layer 3 disposed between the cathode 1 and the anode 2, wherein the active layer 3 contains the semiconductor particles. When the electronic device of this embodiment is a light-emitting device, the active layer functions as a light-emitting layer, and when it is a photovoltaic device, the light-emitting layer functions as an electromotive force layer. Figure 1 shows an example of the layer configuration of the electronic device.

[0055] In one embodiment, the content of semiconductor particles in the active layer 3 is preferably 0.1 to 20 volume%, more preferably 0.5 to 17.5 volume%, and even more preferably 1 to 15 volume%, relative to the total volume of the active layer 3.

[0056] In another embodiment, the content of semiconductor particles in the active layer 3 is preferably 20 to 25% by volume, and more preferably 21 to 24% by volume, relative to the total volume of the active layer 3.

[0057] In another embodiment, the content of semiconductor particles in the active layer 3 is preferably 25% by volume or more, more preferably 27.5% by volume or more, and even more preferably 30% by volume or more, relative to the total volume of the active layer 3. In this embodiment, there is no particular upper limit to the content of semiconductor particles in the active layer 3, but it is preferably 90% by volume or less, more preferably 80% by volume or less, and even more preferably 70% by volume or less.

[0058] Other components constituting the active layer 3 are not particularly limited, but examples of organic host materials include t-butylphenyl biphenyl oxa-diazole (t-PBD).

[0059] Although not shown in Figure 1, the electronic device of this embodiment may have an electron transport layer or a hole transport layer between the cathode 1 and the active layer 3, and / or between the anode 2 and the active layer 3.

[0060] The components constituting the hole transport layer are not particularly limited and may be components used in conventional hole transport layers of electronic devices, but examples include amines, triarylamines, thiophenes, carbazoles, phthalocyanines, porphyrins, and their isomers and derivatives.

[0061] The components constituting the electron transport layer are not particularly limited and may be components used in the electron transport layer of conventional electronic devices, but examples include imidazole, pyridine, pyrimidine, pyridazine, pyrazine, oxadiazole, quinoline, quinoxaline, anthracene, benzanthracene, pyrene, perylene, benzimidazole, triazine, ketone, phosphenoxide, phenazine, phenanthroline, triarylborane, and their isomers and derivatives.

[0062] Furthermore, the electronic device of this embodiment may have a hole injection layer or a charge generation layer between the cathode 1 and the active layer 3, and / or between the anode 2 and the active layer 3. The components constituting the hole injection layer or charge generation layer are not particularly limited, and known materials can be used.

[0063] When the electronic device of this embodiment is a light-emitting device, the peak wavelength of the light emitted by the light-emitting device is preferably 500 nm or less, more preferably 400 to 490 nm, and even more preferably 430 to 485 nm. The peak wavelength of the light emitted by the light-emitting device can be adjusted by the indium content and the size of the semiconductor particles.

[0064] The electronic device of this embodiment is not limited to a light-emitting device, but may be, for example, a light-receiving device. Here, a light-receiving device is a photovoltaic device (solar cell) that absorbs light and generates electricity. When the electronic device is a light-receiving device, the semiconductor particles of this embodiment can be used as a material that generates electricity through light reception. [Examples]

[0065] The present invention will be described more specifically below using examples and comparative examples. The present invention is not limited in any way by the following examples.

[0066] [Example 1] 250 mg of gallium nitride powder and 50 mg of indium nitride powder were added to 20 mL of isopropyl alcohol to form a mixture. While stirring this mixture with a stirrer, a krypton fluoride (KrF) excimer laser was irradiated from above the liquid surface. As a result, In 0.1 Ga 0.9 A transparent solution was obtained in which semiconductor particles of composition N were dispersed in a liquid. The irradiation conditions are as follows. (Irradiation conditions) Output: 100mJ / 1 pulse Oscillation wavelength: 148nm Frequency: 2Hz Irradiation time: 2 hours

[0067] When the obtained transparent solution was evaluated using a particle size analyzer (Otsuka Electronics Co., Ltd., product name ELSZ-1000), it was found that semiconductor particles with an average particle size of 300 nm were dispersed in it.

[0068] Furthermore, the obtained transparent solution was dried on a sample substrate, and the remaining material was observed using a transmission electron microscope (TEM), as shown in Figure 2. As shown in Figure 2, it was found that the transparent solution contained clusters with a diameter of approximately 200 nm, composed of semiconductor nanoparticles with a diameter of approximately 15-20 nm.

[0069] Furthermore, the obtained transparent solution was irradiated with a KrF excimer laser, and photoluminescence evaluation was performed using KrF excimer laser excitation. As a result, blue emission was confirmed from the transparent solution, as shown in Figure 3. In addition, the fluorescence spectra of the transparent solution with and without KrF excimer laser irradiation were measured using an RF-5300PC fluorescence spectrophotometer SHIMADZU (Shimadzu Corporation), and the results are shown in Figure 4. As shown in Figure 4, the transparent solution showed a fluorescence spectrum with a peak wavelength of 427 nm (excitation wavelength 250 nm). Moreover, the sample irradiated with the KrF excimer laser (Figure 4(b)) showed a significantly stronger emission intensity compared to the unirradiated sample (Figure 4(a)). Furthermore, this transparent solution showed absorption emission for more than 100 hours.

[0070] [Example 2] We attempted to fabricate a semiconductor particle light-emitting device on a glass substrate coated with a 150 nm thick ITO (transparent conductive film). First, a 70 nm thick layer of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and a 50 nm thick layer of Poly(9-vinylcarbazole) (PVK) were sequentially deposited on the ITO film by spin coating. Next, the transparent solution prepared in Example 2 was adjusted in concentration and spin-coated on the PVK film at 3,000 RPM for 1 minute to obtain a thin film with a thickness of approximately 300 nm. Furthermore, a 25 nm thick layer of 3,3',5,5'-tetra[(m-pyridyl)-phen-3-yl]biphenyl (BP4mPy), a 1 nm thick layer of lithium fluoride (LiF), and a 100 nm thick layer of aluminum (Al) were fabricated using vacuum deposition. The layer structure of the obtained light-emitting device is shown in Figure 5.

[0071] When a voltage was applied to the obtained light-emitting device and current was injected, voltage-current characteristics and voltage-luminance characteristics were obtained (Figure 6). As shown in Figure 7, it was confirmed that this light-emitting device exhibits blue light emission with a peak around 460 nm. Basic characteristics are shown in Figure 8. [Industrial applicability]

[0072] The present invention has industrial applicability as a raw material for organic light-emitting diodes (OLEDs) that can be used in organic EL display devices, particularly blue-emitting OLEDs, or as a material for solar cell devices that can be manufactured by a coating process. [Explanation of Symbols]

[0073] 1... Cathode, 2... Anode, 3... Active layer

Claims

1. It contains a semiconductor comprising gallium, nitrogen, and indium or aluminum, The average particle size is 100 to 1000 nm. It has polar molecules bonded to its surface by thiol groups, The polar molecule comprises an alkyl group as a spacer group and an organic group as an organic functional group, which includes at least one selected from the group consisting of amines, carbazoles, and phthalocyanines. Semiconductor particles.

2. The aforementioned semiconductor has the following compositional formula (1): X a Ga b N C (In the formula, X represents indium or aluminum, and a, b, and c satisfy the following conditions: 0.7 ≤ a + b ≤ 1.5, 0.01 ≤ a ≤ 0.5, 0.2 ≤ b ≤ 1.49, and 0.8 ≤ c ≤ 1.2.) Represented by, Semiconductor particles according to claim 1.

3. The aforementioned semiconductor has the following compositional formula (2): X a Ga b N C (In the formula, X represents indium or aluminum, and a, b, and c satisfy a + b = 1.0, 0.01 ≤ a ≤ 0.5, and c = 1.) Represented by, Semiconductor particles according to claim 1.

4. The LUMO level is less than -2.0 eV, The band gap is 2.0 eV or greater. Semiconductor particles according to any one of claims 1 to 3.

5. Organic solvents and The organic solvent is dispersed with semiconductor particles according to any one of claims 1 to 4, Semiconductor particle dispersion.

6. It includes a cathode, an anode, and an active layer disposed between the cathode and the anode, The active layer comprises semiconductor particles according to any one of claims 1 to 4. Electronic devices.

7. The active layer contains 25% or more by volume of the semiconductor particles, The electronic device according to claim 6.

8. The active layer comprises 0.1 to 20 volume percent of the semiconductor particles and 50 volume percent or more of the organic host material. The electronic device according to claim 6.

9. Between the cathode or anode and the active layer, there is an electron transport layer or a hole transport layer. The electronic device according to any one of claims 6 to 8.

10. This is a light-emitting device that emits light with a peak wavelength of 500 nm or less. The electronic device according to any one of claims 6 to 9.

11. It is a light-powered device that absorbs light and generates electricity. The electronic device according to any one of claims 6 to 8.

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