An electrically driven quantum dot single photon source and preparation method thereof

Abstract

The present invention provides an electrically driven quantum dot single photon source and a preparation method thereof, wherein the electrically driven quantum dot single photon source comprises a substrate, a positive electrode, a hole injection layer, a quantum dot light-emitting layer, an electron injection layer, and a negative electrode which are arranged in sequence; wherein the quantum dot light-emitting layer comprises an insulating film and quantum dots located in the insulating film and in contact with the hole injection layer, and the material of the quantum dots is silver sulfide. By improving the particle size and distribution design of quantum dots, the selection of materials, the device structure, and other aspects, an electrically driven single photon source which works at a communication wavelength, has high efficiency, has almost no multi-photon emission, has low background noise, and is environmentally friendly is obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor optoelectronic devices, and in particular relates to an electrically driven quantum dot single photon source and a preparation method thereof. Background Art

[0002] Quantum communication is a research field that is the result of the combination of quantum theory and information theory. It is a new type of communication method that uses the quantum entanglement effect to transmit information. It is a means of communication based on the single quantum state of light. Due to its quantum properties based on a single photon, it is essentially unbreakable. Therefore, quantum communication can accomplish confidentiality tasks that classical communication methods cannot accomplish, and has been widely used in quantum cryptography, quantum teleportation, and quantum dense coding.

[0003] The single-photon source is the core component in quantum communication systems. The development trend of quantum communication requires that the single-photon source has the characteristics of simple driving mode, working at the communication wavelength, high single-photon emission efficiency, and minimized multi-photon emission and low background noise. At present, common single-photon sources cannot meet the above requirements at the same time. For example, the single-photon source based on InGaAs quantum dots has low emission efficiency, and the single-photon source based on CdSe quantum dots cannot work in the communication band.

[0004] Therefore, improving transmission efficiency and being able to work in the communication band have become issues that technical personnel in this field need to solve urgently. Summary of the invention

[0005] In view of the shortcomings of the prior art described above, the object of the present invention is to provide an electrically driven quantum dot single photon source and a preparation method thereof, so as to obtain an electrically driven quantum dot single photon source that operates in the communication band, has high efficiency, has almost no multi-photon emission, has low background noise and is environmentally friendly.

[0006] To achieve the above-mentioned purpose and other related purposes, the present invention provides an electrically driven quantum dot single-photon source, which comprises a substrate, a positive electrode, a hole injection layer, a quantum dot light-emitting layer, an electron injection layer, and a negative electrode arranged in sequence; wherein the quantum dot light-emitting layer comprises an insulating film and quantum dots located in the insulating film and in contact with the hole injection layer, and the material of the quantum dots is silver sulfide.

[0007] Optionally, the insulating film comprises a material including polymethyl methacrylate or silicon dioxide.

[0008] Optionally, the quantum dots are in a single layer and dispersedly distributed.

[0009] Optionally, the distance between adjacent quantum dots is greater than or equal to 3 μm.

[0010] Optionally, the vertical distance between the quantum dot and the electron injection layer is 2-3 nm.

[0011] Optionally, the material of the substrate includes any one of quartz glass, transparent ceramics, and polyimide; the material of the positive electrode includes any one of fluorine-doped tin dioxide and indium tin oxide; the material of the hole injection layer includes polyvinyl carbazole; the material of the electron injection layer includes zinc oxide; and the material of the negative electrode includes any one of silver, aluminum, and gold.

[0012] The present invention also provides a method for preparing an electrically driven quantum dot single photon source, which comprises at least the following steps:

[0013] 1) Providing a substrate;

[0014] 2) depositing a positive electrode on the surface of the substrate;

[0015] 3) depositing a hole injection layer on the surface of the positive electrode;

[0016] 4) providing silver sulfide quantum dots, dispersing the quantum dots in a dispersion to form a quantum dot dispersion, and spin coating the quantum dot dispersion on the surface of the hole injection layer;

[0017] 5) depositing an insulating film on the surface of the hole injection layer, wherein the insulating film covers the quantum dots to form a quantum dot light-emitting layer;

[0018] 6) depositing an electron injection layer on the surface of the quantum dot light-emitting layer;

[0019] 7) forming a negative electrode on the surface of the electron injection layer.

[0020] Optionally, the specific process of step 4) includes: providing silver sulfide quantum dots, dispersing the quantum dots in a dispersion, and adding the quantum dots or the dispersion to form a calibrated dispersion with an optical density of 0.1 at 800 nm, further diluting the calibrated dispersion to obtain a quantum dot dispersion, and spin-coating the quantum dot dispersion on the surface of the hole injection layer.

[0021] Optionally, in step 4), the calibration dispersion is further diluted 100,000 to 150,000 times to obtain a quantum dot dispersion.

[0022] Optionally, in step 4), the calibration dispersion is further diluted 200,000 to 250,000 times to obtain a quantum dot dispersion.

[0023] Optionally, in step 4), the calibration dispersion is further diluted 300,000 to 350,000 times to obtain a quantum dot dispersion.

[0024] Optionally, the material of the substrate includes any one of quartz glass, transparent ceramics, and polyimide; the material of the positive electrode includes any one of fluorine-doped tin dioxide and indium tin oxide; the material of the hole injection layer includes polyvinyl carbazole; the material of the electron injection layer includes zinc oxide; and the material of the negative electrode includes any one of silver, aluminum, and gold.

[0025] The present invention obtains an electrically driven single photon source that works at a communication wavelength, has high efficiency, has almost no multi-photon emission, has low background noise, and is environmentally friendly by improving the particle size and distribution design of quantum dots, the material selection, and the device structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Shown is a flow chart of the method for preparing the electrically driven quantum dot single photon source provided by the present invention.

[0027] Figure 2 to Figure 8 Shown are schematic diagrams of various structures in the preparation process of the electrically driven quantum dot single photon source provided by the present invention.

[0028] Figure 2 Shown is a schematic structural diagram of a substrate provided in the preparation of the electrically driven quantum dot single photon source provided by the present invention.

[0029] Figure 3 Shown is a schematic structural diagram of forming a positive electrode in the preparation of the electrically driven quantum dot single photon source provided by the present invention.

[0030] Figure 4 Shown is a schematic structural diagram of forming a hole injection layer in the preparation of the electrically driven quantum dot single photon source provided by the present invention.

[0031] Figure 5 Shown is a schematic diagram of the structure of spin-coated quantum dots in the preparation of the electrically driven quantum dot single-photon source provided by the present invention.

[0032] Figure 6 Shown is a schematic structural diagram of forming a quantum dot light-emitting layer in the preparation of the electrically driven quantum dot single-photon source provided by the present invention.

[0033] Figure 7 Shown is a schematic structural diagram of forming an electron injection layer in the preparation of the electrically driven quantum dot single photon source provided by the present invention.

[0034] Figure 8 Shown is a schematic structural diagram of forming a negative electrode in the preparation of the electrically driven quantum dot single photon source provided by the present invention.

[0035] Component number description

[0036] 11 Base

[0037] 12 Positive electrode

[0038] 13. Hole injection layer

[0039] 141 quantum dots

[0040] 142 Insulation film

[0041] 14 Quantum dot light emitting layer

[0042] 15 Electron injection layer

[0043] 16 Negative electrode

[0044] d Spacing between quantum dots

[0045] h is the vertical distance between the quantum dot and the electron injection layer

[0046] Steps S1 to S7 DETAILED DESCRIPTION

[0047] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0048] See also Figures 1 to 8 It should be noted that the illustrations provided in this embodiment are only schematic illustrations of the basic concept of the present invention. Although the illustrations only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation, the form, quantity and proportion of each component in actual implementation may be changed arbitrarily, and the component layout may also be more complicated.

[0049] Embodiment 1

[0050] This embodiment provides an electrically driven quantum dot single photon source, such as Figure 8 As shown, it mainly includes: from bottom to top, a substrate 11, a positive electrode 12, a hole injection layer 13, a quantum dot light-emitting layer 14, an electron injection layer 15, and a negative electrode 16; wherein the quantum dot light-emitting layer 14 includes an insulating film 142 and silver sulfide quantum dots 141 in contact with the hole injection layer 13.

[0051] The present invention also provides a method for preparing a single-photon detector for regulating superconducting nanowires, such as Figure 1 As shown, the following steps are included:

[0052] 1) Providing a substrate;

[0053] 2) depositing a positive electrode on the surface of the substrate;

[0054] 3) depositing a hole injection layer on the surface of the positive electrode;

[0055] 4) providing silver sulfide quantum dots, dispersing the quantum dots in a dispersion to form a quantum dot dispersion, and spin coating the quantum dot dispersion on the surface of the hole injection layer;

[0056] 5) depositing an insulating film on the surface of the hole injection layer, wherein the insulating film covers the quantum dots to form a quantum dot light-emitting layer;

[0057] 6) depositing an electron injection layer on the surface of the quantum dot light-emitting layer;

[0058] 7) forming a negative electrode on the surface of the electron injection layer.

[0059] The technical solution of the present invention will be described in detail below with reference to the specific drawings.

[0060] See also Figure 1 S1 and Figure 2 , perform step 1) and provide a substrate.

[0061] As an example, the substrate 11 may be a transparent material such as quartz glass, transparent ceramics, polyimide, etc. In this embodiment, quartz glass is selected as the substrate 11.

[0062] See also Figure 1 S2 and Figure 3 , proceed to step 2), depositing a positive electrode 12 on the surface of the substrate 11.

[0063] The material of the positive electrode 12 can be selected from light-transmitting conductive materials such as fluorine-doped tin dioxide or indium tin oxide. In this embodiment, fluorine-doped tin dioxide with good light transmittance, low resistance, wide potential application range, and acid and alkali resistance is selected as the positive electrode layer 12.

[0064] As an example, the method for depositing the positive electrode 12 may be magnetron sputtering, chemical vapor deposition, etc. In this embodiment, magnetron sputtering is used to deposit the positive electrode 12 .

[0065] See also Figure 1 S3 and Figure 4 , proceed to step 3), depositing a hole injection layer 13 on the surface of the positive electrode 12.

[0066] As an example, the material of the hole injection layer 13 can be selected from a mixture of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonate or one of polyvinyl carbazole. In this embodiment, polyvinyl carbazole is selected as the hole injection layer 13. Specifically, in step 2), a 10 mg / mL polyvinyl carbazole chlorobenzene solution is spin-coated onto the positive electrode 12 at a speed of 3000 rpm / min, and then heat-treated at 50°C to 100°C for 30 minutes to obtain the hole injection layer 13.

[0067] See also Figure 1 S4 and Figure 5 , perform step 4), provide silver sulfide quantum dots 141, disperse the quantum dots 141 in a dispersion to form a quantum dot dispersion, and spin-coat the quantum dot dispersion on the surface of the hole injection layer 13.

[0068] As an example, the particle size of the silver sulfide quantum dots 141 is 2 to 4 nm, and is round or nearly round. Silver sulfide quantum dots are luminescent materials, which have almost negligible toxicity, efficient photoluminescence and electroluminescence, adjustable emission wavelength in the first and second near-infrared windows, and efficient Auger recombination. Using the quantum dots as luminescent materials enables the single-photon source to have the advantages of being electrically driven, working at the communication wavelength, high efficiency, almost no multi-photon emission, and being environmentally friendly.

[0069] As an example, the silver sulfide quantum dots 141 are distributed in a single layer and the spacing d between adjacent silver sulfide quantum dots 141 is greater than 3 μm. This ensures that the surrounding quantum dots are not collected during signal collection, thereby avoiding multi-photon emission. The preparation method of the silver sulfide quantum dots 141 can be any one of a microemulsion method, a thermal decomposition method, and a hydrothermal method.

[0070] It should be noted that in step 4), the concentration of the quantum dot dispersion determines the spacing d between the quantum dots. The specific process of step 4) is: disperse the silver sulfide quantum dots 141 in a dispersion, such as ethanol, and then add quantum dots or ethanol to form a standard dispersion with an optical density of 0.1 at 800nm, and then dilute the standard dispersion with ethanol by 100,000 to 150,000 times to obtain a quantum dot dispersion. The obtained quantum dot dispersion is spin-coated onto the hole injection layer at a speed of 5000rmp / min. After the ethanol evaporates, dispersed quantum dots are obtained, and the spacing d between adjacent quantum dots is 3μm to 4μm.

[0071] See also Figure 1 S5 and Figure 6 , proceed to step 5), depositing an insulating film 142 on the hole injection layer, and the insulating film covers the quantum dots 141 to form a quantum dot light-emitting layer 14.

[0072] As an example, the vertical distance h between the quantum dot and the electron injection layer is 2 to 3 nm. Since the electrons are injected from the negative electrode to the quantum dot through the 2 to 3 nm insulating film by the tunnel effect, and the area without quantum dots is too thick because the silicon dioxide film is too weak, the recombination current is concentrated in the quantum dot area, which increases the emission efficiency, slows down the direct exchange of carriers between the hole injection layer and the electron injection layer, avoids a large number of carriers from recombining in the hole injection layer or the electron injection layer and their interface, and finally reduces the background noise.

[0073] As an example, the material of the insulating film 142 may be a material with high transmittance in the near-infrared band, such as silicon dioxide or polymethyl methacrylate. In the present embodiment, silicon dioxide is selected as the material of the insulating film 142 .

[0074] As an example, in step 4), the method of depositing the insulating film includes magnetron sputtering or sol-gel spin coating. Since the surface of the quantum dot light-emitting layer 14 is required to be flat, the sol-gel spin coating is preferably used. Specifically, in step 4), a 5 mg / mL perhydropolysilazane toluene solution is spin-coated at a speed of 5000 rpm / min, and heat-treated at 50°C to 100°C for 30 to 50 minutes to obtain the quantum dot light-emitting layer 14.

[0075] See also Figure 1 S6 and Figure 7 , proceed to step 6), depositing an electron injection layer 15 on the surface of the quantum dot light-emitting layer 14.

[0076] As an example, the material of the electron injection layer 15 can be zinc oxide, etc. In this embodiment, zinc oxide is selected as the electron injection layer. Specifically, in step 6), 10 mg / mL zinc oxide ethanol sol is spin-coated onto the surface of the quantum dot light-emitting layer 14 at a speed of 3000 rpm / min, and heat-treated at 50-100° C. for 30 min to obtain the electron injection layer 15.

[0077] See also Figure 1 S7 and Figure 8 , proceed to step 7) to form a negative electrode 16 on the surface of the electron injection layer 15.

[0078] As an example, the material of the negative electrode 16 can be selected from one of silver, aluminum and gold. In this embodiment, silver is selected as the negative electrode 16. Specifically, in step 7), a silver electrode is deposited on the surface of the electron injection layer 15 by thermal evaporation to form the negative electrode 16.

[0079] The present invention obtains an electrically driven single photon source that works at a communication wavelength, has high efficiency, has almost no multi-photon emission, has low background noise, and is environmentally friendly by improving the particle size and distribution design of quantum dots, the material selection, and the device structure.

[0080] Embodiment 2

[0081] The technical solution of this embodiment is similar to that of the first embodiment, except that in the present embodiment, in step 4), the calibration dispersion is further diluted 200,000 to 250,000 times, and the remaining steps are the same as those of the first embodiment. The distance between quantum dots in the obtained quantum dot light-emitting layer is 5 μm to 6 μm.

[0082] Dispersed quantum dots can ensure that the fluorescence of surrounding quantum dots will not be collected during signal collection, thus avoiding multi-photon emission.

[0083] Embodiment 3

[0084] Example 3 The technical method of this example is similar to that of Example 1. The difference from Example 1 is that in this example, in step 4), the calibration dispersion is further diluted 300,000 to 350,000 times, and the remaining steps are the same as those of Example 1. The distance between quantum dots in the obtained quantum dot light-emitting layer is 7 μm to 8 μm.

[0085] Dispersed quantum dots can ensure that the fluorescence of surrounding quantum dots will not be collected during signal collection, thus avoiding multi-photon emission.

[0086] In summary, the present invention provides an electrically driven quantum dot single photon source and a preparation method thereof, wherein the electrically driven quantum dot single photon source includes, from bottom to top, a substrate, a positive electrode, a hole injection layer, a quantum dot light-emitting layer, an electron injection layer, and a negative electrode; wherein the quantum dot light-emitting layer includes an insulating film and quantum dots located in the insulating film and in contact with the hole injection layer, and the material of the quantum dots is silver sulfide. Based on the above technical scheme, the present invention adopts silver sulfide quantum dots and obtains an electrically driven single photon source that works in the communication band, has high efficiency, has almost no multi-photon emission, has low background noise, and is environmentally friendly by improving the particle size, distribution design, and device structure of the quantum dots. Therefore, the present invention effectively overcomes the various shortcomings of the prior art and has a high industrial utilization value.

[0087] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. An electrically driven quantum dot single photon source, characterized in that: The electrically driven quantum dot single-photon source comprises a substrate, a positive electrode, a hole injection layer, a quantum dot light-emitting layer, an electron injection layer, and a negative electrode arranged in sequence; wherein the quantum dot light-emitting layer comprises an insulating film and quantum dots located in the insulating film and in contact with the hole injection layer, the material of the quantum dots is silver sulfide, and the particle size of the quantum dots is 2-4 nm.

2. The electrically driven quantum dot single photon source according to claim 1, characterized in that: The material of the insulating film includes polymethyl methacrylate or silicon dioxide.

3. The electrically driven quantum dot single photon source according to claim 1, characterized in that: The quantum dots are in a single layer and dispersedly distributed.

4. The electrically driven quantum dot single photon source according to claim 1, characterized in that: The distance between adjacent quantum dots is greater than or equal to 3 μm.

5. The electrically driven quantum dot single photon source according to claim 1, characterized in that: The vertical distance between the quantum dot and the electron injection layer is 2-3 nm.

6. The electrically driven quantum dot single photon source according to claim 1, characterized in that: The material of the substrate includes any one of quartz glass, transparent ceramics, and polyimide; the material of the positive electrode includes any one of fluorine-doped tin dioxide and indium tin oxide; the material of the hole injection layer includes polyvinyl carbazole; the material of the electron injection layer includes zinc oxide; and the material of the negative electrode includes any one of silver, aluminum, and gold.

7. A method for preparing an electrically driven quantum dot single photon source, characterized in that: At least the following steps are included: 1) Providing a substrate; 2) depositing a positive electrode on the surface of the substrate; 3) depositing a hole injection layer on the surface of the positive electrode; 4) providing silver sulfide quantum dots, wherein the particle size of the quantum dots is 2-4 nm, dispersing the quantum dots in a dispersion liquid to form a quantum dot dispersion liquid, and spin coating the quantum dot dispersion liquid on the surface of the hole injection layer; 5) depositing an insulating film on the surface of the hole injection layer, wherein the insulating film covers the quantum dots to form a quantum dot light-emitting layer; 6) depositing an electron injection layer on the surface of the quantum dot light-emitting layer; 7) forming a negative electrode on the surface of the electron injection layer.

8. The method for preparing the electrically driven quantum dot single photon source according to claim 7, characterized in that: The specific process of step 4) includes: providing silver sulfide quantum dots, dispersing the quantum dots in a dispersion, and adjusting the amount of the quantum dots or the dispersion to form a calibrated dispersion with an optical density of 0.1 at 800 nm, further diluting the calibrated dispersion to obtain a quantum dot dispersion, and spin-coating the quantum dot dispersion on the surface of the hole injection layer.

9. The method for preparing an electrically driven quantum dot single photon source according to claim 8, characterized in that: In step 4), the calibration dispersion is further diluted 100,000 to 150,000 times to obtain a quantum dot dispersion.

10. The method for preparing an electrically driven quantum dot single photon source according to claim 8, characterized in that: In step 4), the calibration dispersion is further diluted 200,000 to 250,000 times to obtain a quantum dot dispersion.

11. The method for preparing an electrically driven quantum dot single photon source according to claim 8, characterized in that: In step 4), the calibration dispersion is further diluted 300,000 to 350,000 times to obtain a quantum dot dispersion.

12. The method for preparing an electrically driven quantum dot single photon source according to claim 7, characterized in that: The material of the substrate includes any one of quartz glass, transparent ceramics, and polyimide; the material of the positive electrode includes any one of fluorine-doped tin dioxide and indium tin oxide; the material of the hole injection layer includes polyvinyl carbazole; the material of the electron injection layer includes zinc oxide; and the material of the negative electrode includes any one of silver, aluminum, and gold.

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