KR101060233B1

KR101060233B1 - Semiconductor nanoparticles and optical imaging contrast agent and electronic device comprising the same

Info

Publication number: KR101060233B1
Application number: KR20080092078A
Authority: KR
Inventors: 김성지; 방지원; 원나연
Original assignee: 포항공과대학교 산학협력단
Priority date: 2008-09-19
Filing date: 2008-09-19
Publication date: 2011-08-29
Also published as: KR20100033090A

Abstract

The present invention relates to a semiconductor nanoparticle, and an optical imaging contrast agent and an electronic device comprising the same, the semiconductor nanoparticle is composed of a non-toxic material and can be used as an in vivo image or an eco-friendly LED device, and more than the visible light region Since it has a characteristic of emitting long wavelengths, it can be effectively used in various fields such as an optical amplifier, a laser, an optical display, an optical planar circuit, a light emitting diode, or an optical modulator.

Semiconductor nanoparticles, valence band, conduction band, optical imaging contrast agent

Description

Semiconductor nanoparticles and optical imaging contrasts and electronic devices including the same {Semiconductor Nanoparticles and Optical imaging Contrast Agents and Electrical Devices Comprising the Same}

Embodiments of the present invention relate to semiconductor nanoparticles and optical imaging contrast agents and electronic devices including the same, and more particularly, it is composed of non-toxic materials and can be used as an in vivo image or an eco-friendly light emitting diode device. The present invention relates to a semiconductor nanoparticle having a characteristic of emitting long wavelengths over a region, and an optical imaging contrast agent and an electronic device including the same.

Nanoparticles are materials with crystal structures of several nanoscales and are made up of hundreds to thousands of atoms. The large surface area per unit volume allows most atoms to be present on the surface, resulting in quantum confinement effects.

When these nanoparticles receive light from an excitation source and reach an energy excited state, the nanoparticles emit energy according to an energy band gap, and have unique electrical, magnetic, It has optical, chemical and mechanical properties. Therefore, these nanoparticles can be applied to various devices such as light receiving devices, light emitting devices, and the like, because they can control electrical and optical properties by controlling the size, and research on nanoparticles is being actively made.

In addition, the medical and molecular imaging technology using nanoparticles is rapidly developing. Nanoparticles can be effectively used for medical imaging because their size is similar to the size of important molecules or proteins in the body and can control the emission wavelength according to their size. Therefore, in order to clinicalize and commercialize nanoparticles, it is required to develop biocompatible nanoparticles without losing physical properties and without toxicity in a biological environment.

Embodiments of the present invention are to meet the above technical requirements, one problem to be solved by the present invention is to provide a semiconductor nanoparticle having a characteristic of emitting a long wavelength of more than the visible light region.

Another object of the present invention is to provide an optical imaging contrast agent and an electronic device including the semiconductor nanoparticles that can be used as a molecular label in vivo.

One embodiment of the present invention for solving the above technical problem is

A semiconductor nanoparticle having a multilayer structure including two or more semiconductor layers composed of one or more semiconductor materials, wherein the semiconductor nanoparticles have one or more interfaces where a band gap intersects, and a material constituting the semiconductor layer is And a semiconductor material selected from the group consisting of group II-VI compounds, group III-V compounds, group IV-VI compounds, and mixtures thereof, which do not contain cadmium, mercury, lead and arsenic elements. It relates to a semiconductor nanoparticle.

Another embodiment of the present invention for solving the above problems is a multi-layer structure, and relates to an optical imaging contrast agent comprising semiconductor nanoparticles having one or more semiconductor interfaces intersecting the band gap.

Another embodiment of the present invention for solving the above problems relates to an electronic device which is an optical amplifier, a laser, an optical display, an optical planar circuit, a light emitting diode or an optical modulator including the semiconductor nanoparticles.

The semiconductor nanoparticles of various embodiments of the present invention are semiconductor nanoparticles having one or more semiconductor interfaces having cross band intervals. The semiconductor nanoparticles are made of non-toxic materials and can be used as an in vivo image or an eco-friendly LED device. Since it has a characteristic of emitting a longer wavelength than the region, it can be effectively applied in various fields such as an optical amplifier, a laser, an optical display, an optical planar circuit, a light emitting diode or an optical modulator.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

As used herein, the terms "semiconductor nanoparticle" and "quantum dot" are used interchangeably and refer to semiconductor nanoparticles composed of crystalline inorganic materials having luminescent properties. Expressed herein as “ZnTe / ZnSe” refers to a quantum dot of a core-shell structure in which the core is composed of ZnTe and the shell is composed of ZnSe.

The semiconductor nanoparticle of one embodiment of the present invention is a semiconductor nanoparticle having a multilayer structure including two or more semiconductor layers composed of one or more semiconductor materials, wherein the semiconductor nanoparticles have one or more interfaces where band gaps intersect. The material constituting the semiconductor layer is selected from the group consisting of Group II-VI compounds, Group III-V compounds, Group IV-VI compounds, and mixtures thereof that do not contain cadmium, mercury, lead, and arsenic elements. Semiconductor material.

Here, "crossing the band gap" means that both the conduction band and the valence band of the semiconductor material of one layer in the semiconductor nanoparticles composed of two or more layers made of different semiconductor materials, the conduction band and the consumer It means higher or lower than Jati.

At this time, the II-VI compound is a binary element of ZnO, ZnS, ZnSe, ZnTe; And ZnSeS, ZnSeTe, ZnSTe is a substance selected from the group consisting of three-element compound,

Group III-V compounds include GaN, GaP, GaSb, AlN, AlP, AlSb, InN, InP, InSb; Three-element compounds of GaNP, GaNSb, GaPSb, AlNP, AlNSb, AlPSb, InNP, InNSb, InPSb; And an element selected from the group consisting of GaAlNSb, GaAlPSb, GaInNP, GaInNSb, GaInPSb, InAlNP, InAlNSb, InAlPSb,

The IV-VI compound is a binary element compound of SnS, SnSe, SnTe; And it may be a material selected from the group consisting of a three-element compound of SnSeS, SnSeTe, SnSTe.

1 is a schematic view of a semiconductor nanoparticle of one embodiment of the present invention. Referring to FIG. 1, a semiconductor nanoparticle of an embodiment of the present invention includes a first semiconductor layer 10 and a second semiconductor layer 20. 1 illustrates a semiconductor nanoparticle composed of two layers, but may also include another semiconductor layer as needed.

1, the valence band and conduction band of the material of the second semiconductor layer 20 are lower than those of the material of the first semiconductor layer 10, or as shown in FIG. 1. As shown in FIG. 2, the valence band and conduction band of the material of the second semiconductor layer 20 are higher than the valence band and conduction band of the material of the first semiconductor layer 10.

In general multilayer semiconductor nanoparticles, the conduction band and valence band of the material constituting the shell are located at a higher energy and a lower energy than the conduction band and valence band of the core material, respectively. There is a high probability of being bound by matter.

In contrast, semiconductor nanoparticles of embodiments of the present invention have a tendency to separate the electrons and holes spatially from each other without being bound in one layer due to the intersecting band gap. First, the electrostatic attraction of electrons and holes is reduced compared to general semiconductor nanoparticles. Second, the interference effect of electrons and holes by external electric fields may have different characteristics from that of general semiconductor nanoparticles.

In the semiconductor nanoparticles of the embodiment of the present invention, the electrons and holes are spatially distributed in different semiconductor layers. In other words, one carrier (electron or hole) has a high probability of being present in the first semiconductor layer 10 and another carrier having an opposite polarity has a high probability of being present in the second semiconductor layer 20. Specifically, as shown in FIG. 1, the semiconductor nanoparticles (eg, ZnTe /) having lower valence bands and conduction bands of the second semiconductor layer 20 material than lower valence bands and conduction bands of the first semiconductor layer 10 material. In the case of ZnSe, electrons (e ⁻ ) that are excited at the time of excitation are relatively more likely to exist in the second semiconductor layer 20, and holes (h ⁺ ) are more likely to be present in the first semiconductor layer 10. Meanwhile, as shown in FIG. 2, semiconductor nanoparticles (eg, ZnSe / ZnTe) having a valence band and a conduction band of the material of the second semiconductor layer 20 are higher than those of the material of the first semiconductor layer 10. ), Electron (e ⁻ ) has a high probability of being present in the first semiconductor layer 10, and hole (h ⁺ ) has a high probability of being present in the second semiconductor layer 20.

The semiconductor nanoparticles of various embodiments of the present invention are greatly influenced by the spatial separation between electrons and holes and different quantum limiting effects of electrons and holes present in different spaces (first semiconductor layer and second semiconductor layer). Will receive.

Such semiconductor nanoparticles may have a smaller band gap than the band gap of the material constituting each semiconductor layer. That is, considering the energy positions of the conduction band and the valence band of the semiconductor material constituting each semiconductor layer, the electron-hole pairs excited in the semiconductor nanoparticles of the present invention are spatially separated into respective semiconductor layers, Recombination at the interface of the semiconductor layer emits photons of energy corresponding to the actual band gap smaller than the band gap of the semiconductor material constituting each semiconductor layer.

Figure 3 is a graph showing the band gap according to the energy level of the ZnTe / ZnSe semiconductor nanoparticles of one embodiment of the present invention. Referring to FIG. 3, the valence band and conduction band of the ZnSe shell are lower than those of the ZnTe core, and the effective band gap due to the energy difference between electrons (e ⁻ ) and holes (h ⁺ ) of the ZnTe / ZnSe semiconductor nanoparticles is determined by conduction of the ZnSe shell. This value is similar to the energy gap between the band and the valence band of the ZnTe core, which is smaller than the energy gap of the ZnTe semiconductor or the ZnSe semiconductor. It may have a smaller real band gap than the band gap.

At this time, the thickness of the semiconductor layer constituting the semiconductor nanoparticles is not particularly limited, but the radius of the core layer and the thickness of the shell layer determines the absorption and emission wavelengths by the quantum limiting effect peculiar to the quantum dots, so that the semiconductor nanoparticles By varying the material constituting the or by adjusting the size can be synthesized semiconductor nanoparticles capable of emitting visible and infrared regions.

The semiconductor nanoparticles may be a core-shell, core-multishell or core-intermediate-shell structure. When the core and the shell are multi-layered, the band gaps intersect according to the energy levels of the valence and conduction bands of each layer and the thickness of each layer, and thus the electrons and holes can be separated into space. I can regulate it. In addition, the semiconductor nanoparticle of the present invention may further include a protective layer that does not significantly affect light emission in the intermediate layer or the outermost layer of the semiconductor nanoparticle.

The core or shell is ZnO, ZnS, ZnSe, ZnTe, ZnSeS, ZnSeTe, ZnSTe, GaN, GaP, GaSb, AlN, AlP, AlSb, InN, InP, InSb GaNP, GaNSb, GaPSb, AlNP, AlNSb, AlPSb, InNP, It may include a material selected from the group consisting of InNSb, InPSb, GaAlNSb, GaAlPSb, GaInNP, GaInNSb, GaInPSb, InAlNP, InAlNSb, InAlPSb, SnS, SnSe, SnTe, SnSeS, SnSeTe, and SnSTe.

In this case, the semiconductor nanoparticles of the core-shell, core-multi-shell, or core-intermediate-shell structure may have one or more interfaces where a band gap crosses.

In particular, the semiconductor layer is preferably composed of a non-toxic material that does not contain cadmium, mercury, lead and arsenic elements, such semiconductor nanoparticles can be easily used as a molecular label in vivo. Such semiconductor nanoparticles are ZnTe / ZnSe, ZnSe / ZnTe, ZnTe / ZnO, ZnO / ZnTe, ZnSe / ZnO, ZnO / ZnSe, ZnS / ZnO, ZnO / ZnS, ZnTe / ZnS, ZnS / ZnTe, InP / ZnTe Or ZnTe / ZnSe / ZnS, ZnTe / ZnS / ZnSe, ZnSe / ZnTe / ZnS, ZnSe / ZnS / ZnO, ZnO / ZnS / ZnSe, ZnS / ZnO / ZnSe, ZnO / ZnS / ZnSe , ZnO / ZnS / ZnTe, ZnO / ZnTe / ZnS, ZnTe / ZnO / ZnS, ZnS / ZnTe / ZnSe, ZnS / ZnSe / ZnT, InP / ZnTe / ZnSe, ZnTe / InP / ZnSe, InP / ZnTn It may be selected from the group consisting of / InP / ZnSe.

The method of manufacturing the semiconductor nanoparticles of the present invention is not particularly limited, and examples thereof include organic metal chemical vapor deposition (OMCVD) or molecular beam epitaxy (MBE) systems and chemical wet methods. Can be prepared by

The semiconductor nanoparticles of one embodiment of the present invention are synthesized by a chemical wet method, which mainly produces a uniform nucleus and then grows around the nucleus with temperature and time. In the chemical wet method, a precursor material capable of growing crystals in a coordinable organic solvent is applied to the surface of the nanoparticles to control the size of the quantum dots by preventing the growth of the quantum dots as the organic solvent is coordinated to the quantum dot crystal surface. The quantum dots are evenly dispersed by the organic solvent. Chemical wet manufacturing methods of quantum dots are well known in the art, for example, US Pat. Nos. 6,322,901 and 6,207,229. The manufacturing method of a quantum dot etc. is disclosed. In the present invention, it is prepared by a method similar to that disclosed in this document, but by selecting the semiconductor material of each layer such that the semiconductor nanoparticles at one or more interfaces cross the band gap.

According to one embodiment of the invention, the semiconductor nanoparticles first disperse the precursor materials in a solvent such as trioctyl phosphine to form a core, and then trioctylphospine oxide under a nitrogen environment ) And the hexadecylamine (hexadecylamine) is injected into a mixed solution to synthesize a core.

Subsequently, the core synthesized above and a solvent such as trioctylphospine oxide are mixed and heated under a nitrogen environment. At this time, the heating step may vary depending on the material and precursor of the quantum dot, but may be generally performed at 50 to 400 ℃ for 10 to 500 minutes.

Thereafter, a solution obtained by dispersing the precursor of the shell in a solvent such as trioctyl phosphine is added to the mixed solution formed in the above step, and then heated to synthesize semiconductor nanoparticles. At this time, the heating step may vary depending on the material and precursor of the quantum dot, but generally may be performed for 10 to 1000 minutes at 50 to 400 ℃.

Precursors usable in embodiments of the present invention specifically include dimethyl zinc, diethyl zinc, zinc acetate, zinc acetylacetonate, zinc iodide iodide, zinc bromide, zinc chloride, zinc fluoride, zinc carbonate, zinc carbonate, zinc cyanide, zinc nitrate, zinc oxide Zinc oxide, Zinc peroxide, Zinc perchlorate, Zinc sulfate, Diphenyl zinc, Zinc naphthenate, Zinc stearate , Aluminum acetate, aluminum iodide, aluminum bromide, aluminum chloride, aluminum plaque Aluminum fluoride, Aluminum nitrate, Aluminum oxide, Aluminum perchlorate, Aluminum carbide, Aluminum stearate, Aluminum sulphate , Di-i-butylalumium chloride, Diethylalumium chloride, Tri-i-butylaluminum, Triethylalumium, triethyl ( Tri- (tri-sec-butoxy) dialuminum, Trimethylalumium, Gallium acetylacetonate, Gallium chloride, Gallium fluoride , Gallium oxide, gallium nitrate, gallium sulfate, gallium iodide, trie Triethyl gallium, Trimethyl gallium, Indium chloride, Indium oxide, Indium nitrate, Indium sulfate, Indium acetate, Indium Acetylacetonate, indium bromide, indium fluoride, trimethyl indium, tin acetate, tin bisacetylacetonate, tin bromide Tin bromide, Tin chloride, Tin fluoride, Tin oxide, Tin sulfate, Tin iodide, Diphenyly dichloride ), Germanium tetrachloride, germanium oxide, germanium ethoxide, germanium Bromide (Germanium bromide), Germanium iodide, Tetramethyl germanium, Trimethyl germanium chloride, Trimethyl germanium bromide, Triethyl germanium chloride , Tri-n-octylphosphine selenide, tri-n-butylphosphine selenide, diethyl diselenide, dimethyl selenide (Dimethyl selenide), bis (trimethylsilyl) selenide, selenium-triphenylphosphine (Se-TPP), tri-n-octylphosphine telluride , Tri-n-butylphosphine telluride, bis (trimethylsilyl) telluride bis-triphenylphosphine (Te-TPP), sulfur-trioctylfo Spin (S-TOP), sulfur-tributylphosphine (S-TBP), sulfur-triphenylphosphine (S-TPP), sulfur-trioctylamine (S-TOA), bis (trimethyl silly) sulfide (bis trimethylsilyl sulfide trimethylsilyl sulfur, ammonium sulfide, sodium sulfide, trimethylsilyl phosphine and triethylphosphine, tributylphosphine, trioctylphosphine, triphenylphosphine, tricyclo Alkyl phosphine including hexylphosphine, Tris (hydroxypropyl) phoshine, Di-tert-butylphosphine, Nitriud oxide), nitric acid (Nitric acid) and ammonium nitrate (Ammonium nitrate).

Solvents usable in embodiments of the present invention are trioctylphosphine oxide, hexadecane, 1-hexadecene. In the group consisting of octadecane, 1-octadecene, 1-octadecene, heptadecane, 1-heptadecine, nonadecane, and trioctyl phosphine Can be selected.

On the other hand, according to another embodiment of the present invention, the semiconductor nanoparticles have photochemical stability and have excellent light emission characteristics from visible to near infrared region. In addition, the semiconductor nanoparticles are capable of various surface modifications, do not contain heavy metals such as cadmium, lead, etc., that is composed of a material that does not have toxicity in vivo, so that various kinds of nanobio devices for bioimaging, biolabeling, etc. It can be used for, in particular can be used as an optical imaging contrast agent.

According to one embodiment of the present invention, semiconductor nanoparticles having ZnTe and ZnSe semiconductors as core and shell materials may be synthesized, and light emitting characteristics of the semiconductor nanoparticles may be used as optical imaging contrast agents, which may be used as CdSe, PbSe and Compared with the same semiconductor nanoparticles, they are relatively less toxic and have longer wavelengths than the energy corresponding to the band gap of the composition of each core and shell because the conduction band and valence band of ZnTe and ZnSe constituting the core and shell cross each other. Since it emits light, there is an advantage to increase the in vivo permeability of the emitted light when used as an optical imaging medium in vivo.

Meanwhile, another aspect of the present invention relates to an electronic device including semiconductor nanoparticles according to various embodiments of the present invention, which not only emits light having a long wavelength but also has excellent luminous efficiency, such as an optical amplifier, a laser, an optical display, and an optical device. It may be used in a planar circuit, a light emitting diode or an optical modulator, etc., but is not necessarily limited thereto.

In addition, the semiconductor nanoparticles according to the present invention has a characteristic of separating the electrons and holes spatially can be utilized as a function having a small threshold when used as an optical device such as a laser, it does not contain heavy metals such as cadmium, lead It has the potential to be used as an in vivo image of an infrared region or as an environmentally friendly LED device.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the following Examples are for illustrative purposes only and are not intended to limit the present invention.

Example One : ZnTe Of ZnSe Synthesis of Semiconductor Nanoparticles

First, 0.5 mmol of diethyl zinc and 1 mmol of trioctylphosphine telluride are dispersed in 2 ml of trioctyl phosphine as precursor materials of the ZnTe core, and then, under nitrogen atmosphere at 300 ° C. ZnTe cores were synthesized by injection into a mixed solution of 2.5 ml of 1-octadecene (1-Octadecene) and 1.5 g of hexadecylamine.

Subsequently, the synthesized ZnTe core and trioctylphospine oxide were mixed and heated to 150 to 180 ° C. under a nitrogen environment.

Thereafter, 0.15 mmol of diethyl zinc and 0.15 mmol of trioctylphosphine selenide were dispersed in 2 ml of trioctyl phosphine as precursors of ZnSe shell in the mixed solution formed in the step. After dropwise dropwise, ZnTe / ZnSe semiconductor nanoparticles were synthesized by stirring and heating at 180-250 ° C. to grow a ZnSe crystal structure on the surface of the ZnTe core.

Example 2: ZnTe Of ZnSe Synthesis of Semiconductor Nanoparticles

In the present embodiment is the same as in Example 1 except that the amount of diethyl zinc and trioctylphosphine selenide precursor materials of ZnSe shell was used as 0.3 mmol and 0.3 mmol, respectively ZnTe / ZnSe semiconductor nanoparticles were synthesized.

Example 3: ZnTe Of ZnSe Synthesis of Semiconductor Nanoparticles

In the present embodiment is the same as in Example 1 except that the amount of diethyl zinc and trioctylphosphine selenide precursor materials of ZnSe shell are used as 0.4 mmol and 0.4 mmol, respectively ZnTe / ZnSe semiconductor nanoparticles were synthesized.

Example 4 : ZnTe Of ZnSe Synthesis of Semiconductor Nanoparticles

In the present embodiment is the same as in Example 1 except that the amount of diethyl zinc and trioctylphosphine selenide precursor materials of ZnSe shell was used as 0.55 mmol and 0.55 mmol, respectively ZnTe / ZnSe semiconductor nanoparticles were synthesized. Fluorescence spectra and transmission electron microscope (TEM) photographs of the synthesized semiconductor nanoparticles are shown in FIGS. 4 and 5, respectively.

Absorption and fluorescence spectra of the ZnTe / ZnSe semiconductor nanoparticles prepared in Examples 1-4 are shown in FIGS. 6 and 7, respectively. 6 and 7, if the amount of zinc precursor and selenium precursor used is different, the thickness of the ZnSe shell of the ZnTe / ZnSe semiconductor nanoparticles formed as the amount of the added zinc precursor and selenium precursor is increased is expected to increase. As the thickness of the ZnSe shell increases, it can be seen that the absorption and emission wavelengths move toward the longer wavelengths.

Example 5: ZnTe Of ZnSe Cell Imaging of Semiconductor Nanoparticles

The ZnTe / ZnSe semiconductor nanoparticles synthesized in Example 4 were added with an excess of dihydrolipoic acid, and stirred and heated for about 2 hours in a nitrogen environment at 80 ° C. to replace the surface with dihydrolipoic acid. To obtain a quantum dot whose surface is negatively charged.

Subsequently, quantum dots with negative charge on the surface of Dulbecco's modified eagle's medium (DMEM) and lipofectamine were mixed and electrostatically attracted, and then incubated in cervical cancer cell medium for about 2 hours.

Subsequently, the quantum dot-cell medium was washed several times with PBS (phosphate buffered saline) solution to remove the unquantized quantum dots in the cells. Then, the optical microscope transmission image and the optical microscope fluorescence image are shown in Figs. 8 and 9, respectively.

Although a preferred embodiment of the present invention has been described in detail above, those skilled in the art will be able to carry out various modifications or changes without departing from the spirit and scope of the present invention. Therefore, all such possible modifications or variations should be understood to fall within the protection scope of the present invention.

1 is a schematic diagram showing a semiconductor nanoparticle and one embodiment thereof in one embodiment of the present invention,

Figure 2 is a schematic diagram showing a semiconductor nanoparticle and another band gap of another embodiment of the present invention,

Figure 3 is a graph showing the band gap according to the energy level of the semiconductor nanoparticles of one embodiment of the present invention,

4 is a fluorescence spectrum of the semiconductor nanoparticles prepared by Example 4,

5 is a transmission electron microscope image of a semiconductor nanoparticle prepared in Example 4,

6 is an absorption spectrum of the semiconductor nanoparticles prepared by Examples 1 to 4,

7 is a fluorescence spectrum of the semiconductor nanoparticles prepared by Examples 1 to 4,

8 is an optical microscope transmission image of cervical cancer cells captured by the semiconductor nanoparticles prepared in Example 5,

9 is an optical microscope fluorescence image of cervical cancer cells captured by the semiconductor nanoparticles prepared in Example 5.

10: first semiconductor layer 20: second semiconductor layer

Claims

A semiconductor nanoparticle having a multilayer structure including two or more semiconductor layers composed of one or more semiconductor materials, wherein the semiconductor nanoparticles have one or more interfaces where a band gap intersects, and a material constituting the semiconductor layer is A semiconductor material selected from the group consisting of Group II-VI compounds, Group III-V compounds, Group IV-VI compounds, and mixtures thereof that do not contain cadmium, mercury, lead, and arsenic elements,

Group II-VI compounds include ZnS, ZnSe, ZnTe binary elements; And ZnSeS, ZnSeTe, ZnSTe is a substance selected from the group consisting of three-element compound,

The IV-VI compound is a binary element compound of SnS, SnSe, SnTe; And SnSeS, SnSeTe, or SnSTe tri-element compound. A semiconductor nanoparticle, characterized in that the material selected from the group consisting of.

delete

2. The household appliance of claim 1, wherein the semiconductor nanoparticle has a conductive band of the semiconductor material of the first semiconductor layer of the semiconductor nanoparticle higher than the conductive band of the semiconductor material of the second semiconductor layer. The semiconductor nanoparticles characterized in that the strip is higher than the valence band of the semiconductor material of the second semiconductor layer.

The electrical appliance of claim 1, wherein the conductive band of the semiconductor material of the first semiconductor layer of the semiconductor nanoparticle is lower than the conductive band of the semiconductor material of the second semiconductor layer. The semiconductor nanoparticles characterized in that the magnetic strip is lower than the valence band of the semiconductor material of the second semiconductor layer.

The semiconductor nanoparticle of claim 1, wherein the semiconductor nanoparticle is spatially separated from electrons or holes upon excitation so that the semiconductor nanoparticles are localized in semiconductor layers having different electrons and holes.

The semiconductor nanoparticle of claim 1, wherein the semiconductor nanoparticle has a core-shell, core-multishell, or core-interlayer-shell structure.

The method of claim 6, wherein the core or shell is ZnS, ZnSe, ZnTe, ZnSeS, ZnSeTe, ZnSTe, GaN, GaP, GaSb, AlN, AlP, AlSb, InN, InP, InSb GaNP, GaNSb, GaPSb, AlNP, AlNSb, AlPSb, InNP, InNSb, InPSb, GaAlNSb, GaAlPSb, GaInNP, GaInNSb, GaInPSb, InAlNP, InAlNSb, InAlPSb, SnS, SnSe, SnTe, SnSeS, SnSeTe and SnSTe, and the material selected from the group consisting of the core-shell The semiconductor nanoparticles of the core-multi-shell or core-intermediate-shell structure have at least one interface with a band gap crossing.

The semiconductor nanoparticle of claim 1, wherein the semiconductor nanoparticles have a substantial band gap smaller than the band gap of the material constituting each semiconductor layer.

The semiconductor nanoparticle of claim 6, wherein the semiconductor nanoparticle is selected from the group consisting of ZnTe / ZnSe, ZnSe / ZnTe, ZnTe / ZnS, ZnS / ZnTe, InP / ZnTe, and ZnTe / InP.

The method of claim 6, wherein the semiconductor nanoparticles are ZnTe / ZnSe / ZnS, ZnTe / ZnS / ZnSe, ZnSe / ZnTe / ZnS, ZnS / ZnTe / ZnSe, ZnS / ZnSe / ZnTe, InP / ZnTe / ZnSe, ZnTe / InP / ZnSe, InP / ZnTe / ZnS and ZnTe / InP / ZnSe semiconductor nanoparticles, characterized in that selected from the group consisting of.

An optical imaging contrast agent comprising the semiconductor nanoparticles according to claim 1.

An electronic device comprising the semiconductor nanoparticles according to any one of claims 1 or 3 to 10.

The electronic device of claim 12, wherein the electronic device is an optical amplifier, a laser, an optical display, an optical planar circuit, a light emitting diode, or an optical modulator.