Infrared absorbing quantum dot and method for manufacturing infrared absorbing quantum dot

Abstract

An infrared-absorbing quantum dot according to an embodiment of the present invention is an infrared-absorbing quantum dot containing silver (Ag) and tellurium (Te), the infrared-absorbing quantum dot containing an absorbance peak in the range of 1400 nm to 1800 nm, and the ratio of peak to valley (peak / valley) of the absorbance peak being 1.0 or more.

Description

Technical Field

[0001] The invention relates to infrared absorption quantum dots and a method for producing the infrared absorption quantum dots.

[0002] This application claims priority based on U.S. Provisional Application No. 63 / 369,804 filed on July 29, 2022, the contents of which are incorporated into this specification by reference. Background Art

[0003] Many optoelectronic devices, such as photovoltaic devices, electrical communication devices, sensor devices, and in vivo bioimaging materials, use materials that absorb light in the infrared (IR) region of the electromagnetic spectrum. Depending on the circumstances, it may be advantageous to use materials with an absorbance peak in a range exceeding 1400 nm. This can increase the signal-to-noise ratio of the light absorbed by the device. For example, this region overlaps with the emission peak of an IR light source (e.g., a 1450 nm laser).

[0004] Prior art literature

[0005] Non-patent literature

[0006] Non-patent document 1: Zhen-Ya Liu, et al., "Breaking through the Size ControlDilemma of Silver Chalcogenide Quantum Dots via Trialkylphosphine-InducedRipening: Leading to Ag2Te Emitting from 950 to 2100 nm" Journal of the American Chemical Society, vol. 143, issue 32, 2021, pp12867-12877

[0007] Non-patent literature 2: Jianying Ouyang, et al., “Ag2Te Colloidal Quantum Dotsfor Near-Infrared-II Photodetectors” ACS Applied Nano Materials, vol. 4, issue 12, 2021, pp13587-13601 Summary of the invention

[0008] Technical problem to be solved by the invention

[0009] Depending on the situation, single crystal semiconductors such as gallium arsenide can be used as IR absorbing materials. However, it is difficult to manufacture some devices using single crystal semiconductors. For example, a detector for an IR camera may include an array of pixels, each pixel including a single crystal semiconductor configured on a silicon backplane. However, it is technically difficult to cut the single crystal semiconductor into parts corresponding to the pixels and configure each part on the backplane of the array, which may be costly and time-consuming. In addition, it is difficult to manufacture a silicon-based detector that selectively absorbs light in a range exceeding 1400nm.

[0010] In other examples, quantum dots (QDs) can be used to absorb IR light. For example, lead-based QDs, cadmium-based QDs, and mercury-based QDs can strongly absorb in the range of 1400nm to 1500nm. However, heavy metal-based QDs may be difficult to use in biological and medical applications. In addition, heavy metals may pose environmental risks when discarded.

[0011] As mentioned above, quantum dots (hereinafter also referred to as "QDs") based on heavy metals such as lead, cadmium and mercury can strongly absorb in the range of more than 1400nm. However, heavy metal-based QDs may pose environmental and health risks. 2 S, Ag 2 Se and Ag 2 Silver chalcogenide QDs can be used as a less toxic alternative to heavy metal-based QDs. However, silver chalcogenide QDs may have a shorter absorption peak wavelength (e.g., less than 1400 nm), a larger half-width at half maximum (HWHM) of the absorption peak, and / or a smaller peak-to-valley ratio (e.g., less than 1.0) than heavy metal-based QDs (e.g., PbS). This can result in poor absorption at target wavelengths (e.g., in the range of 1400 nm to 1800 nm) and / or a smaller or undetectable signal-to-noise ratio compared to the use of heavy metal-based QDs.

[0012] Therefore, an object of the present invention is to provide a quantum dot that can absorb infrared light above 1400 nm and does not substantially contain heavy metals.

[0013] Technical means of solving problems

[0014] The infrared absorption quantum dots according to the embodiment of the present invention are infrared absorption quantum dots containing silver (Ag) and tellurium (Te).

[0015] The infrared absorption quantum dots include an absorbance peak in the range of 1400nm to 1800nm,

[0016] The peak-to-valley ratio (peak / valley) of the absorbance peak is 1.0 or more.

[0017] The method for producing infrared absorption quantum dots according to an embodiment of the present invention is a method for producing infrared absorption quantum dots according to an embodiment of the present invention, comprising:

[0018] a step of forming a core of a quantum dot seed crystal containing silver (Ag) and tellurium (Te); and

[0019] The process of forming infrared absorption quantum dots comprises adding a chalcogen precursor to grow quantum dot seed crystals, thereby forming infrared absorption quantum dots having an absorbance peak in the range of 1400nm to 1800nm,

[0020] The peak-to-valley ratio (peak / valley) of the absorbance peak is greater than 1.0,

[0021] The chalcogen precursor includes tellurium (Te).

[0022] Another embodiment of the present invention is an infrared absorbing quantum dot comprising: a core containing silver (Ag) and tellurium (Te), and a shell containing silver (Ag), tellurium (Te) and selenium (Se), wherein:

[0023] The infrared absorption quantum dots include an absorbance peak in the range of 1400nm to 1800nm,

[0024] The peak-to-valley ratio (peak / valley) of the absorbance peak is 1.0 or more.

[0025] Effects of the Invention

[0026] According to an embodiment of the present invention, quantum dots that can absorb infrared light above 1400 nm and are substantially free of heavy metals can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] [ Figure 1 ] Figure 1 1 is an example of infrared absorbing quantum dots containing silver and tellurium according to an exemplary embodiment of the present invention.

[0028] [ Figure 2 ] Figure 2 FIG. 1 is a transmission electron microscope (TEM) image showing a plurality of infrared absorbing quantum dots including silver and tellurium according to an exemplary embodiment of the present invention.

[0029] [ Figure 3 ] Figure 3 This is a graph showing absorbance spectra of a plurality of infrared absorption quantum dot groups formed so as to have different molar ratios of silver-telluride according to an exemplary embodiment of the present invention.

[0030] [ Figure 4 ] Figure 4] is an example of infrared absorbing quantum dots containing silver, tellurium, and selenium according to another exemplary embodiment of the present invention.

[0031] [ Figure 5 ] Figure 5 TEM image showing a plurality of infrared absorbing quantum dots including silver, tellurium, and selenium according to an exemplary embodiment of the present invention.

[0032] [ Figure 6 ] Figure 6 Graph showing the absorbance spectrum of a group of infrared absorbing quantum dots having a Se-Te-like shell.

[0033] [ Figure 7 ] Figure 7 1 is an X-ray fluorescence spectrum of a sample used for infrared absorbing quantum dots according to an exemplary embodiment of the present invention.

[0034] [ Figure 8 ] Figure 8 is a flow chart showing a method for preparing infrared absorbing quantum dots according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0035] In this specification, examples of infrared (IR) absorbing quantum dots comprising silver (Ag) and tellurium (Te) and methods for making the same are disclosed. The infrared absorbing quantum dots comprise an absorbance peak in the range of 1400 nm to 1800 nm, and the peak-to-valley ratio (peak / valley) of the absorbance peak is greater than 1.0. Advantageously, the infrared absorbing quantum dots are substantially free of heavy metal elements. The term "substantially free of heavy metal elements" may generally refer to quantum dots that do not have heavy metal elements other than potential trace impurities present in the reaction product used to prepare the quantum dots.

[0036] This Summary is provided to introduce in a simplified form a selection of concepts that are further described in the Detailed Description of the Invention. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0037] Figure 1 An example of an infrared absorbing quantum dot 100 is shown. Figure 1 As shown in the example, the infrared absorbing quantum dot 100 is formed by the following two steps (such as seed growth): the step of forming a core of the QD seed 102 using a silver precursor 104 and a chalcogen precursor 106, and the step of subsequently adding additional chalcogen precursor 106 to grow the QD seed.

[0038] The QD seed 102 contains silver and tellurium. For example, the QD seed 102 can be in the form of Ag-Te. In some instances, the QD seed is nucleated by hot injection. In the hot injection method, the chalcogen precursor 106 is rapidly added to a high temperature (e.g., 150°C) solution of the silver precursor 104. The silver precursor 104 and the chalcogen precursor 106 can contain any appropriate material. As an example of a suitable chalcogen precursor 106, trioctylphosphine telluride (TOPTe) can be cited. As an example of a preferred silver precursor 104, silver acetate can be cited. Any appropriate solvent can be used in the reaction. In some instances, silver acetate can be dissolved in octanethiol.

[0039] In some examples, the chalcogen precursor 106 is added to a solution containing excess silver. This allows the amount of chalcogen precursor 106 to control the size and dispersion of the resulting QD seeds, as well as the chemical weight ratio of silver and tellurium in the solution. The molar ratio of Ag:Te (Ag / Te) is referred to as Figure 3 and is described in more detail below.

[0040] In some examples, the QD seed 102 grows in the reaction mixture for up to 1 hour. For example, the QD seed 102 can be grown for 40 minutes. In another example, the QD seed 102 grows for more than 1 hour. In some examples, the QD seed 102 grows at a temperature in the range of 80°C to 200°C. In another example, the QD seed 102 grows at a temperature in the range of 120°C to 180°C. In another example, the QD seed 102 grows at a temperature in the range of 140°C to 160°C. In longer reaction times, the absorbance peak moves to longer wavelengths, and in addition, the peak-to-valley ratio (peak / valley) can be reduced. It is not desired to be bound by theory, but this may be caused by particle growth produced at different times and / or speeds, resulting in a larger range of particle sizes and correspondingly wider absorbance peaks. Additionally or alternatively, this may be caused by the loss of ligand coating around infrared absorbing quantum dots.

[0041] The QD seed crystal 102 is used as a basis for growing the infrared absorbing quantum dots 100. Figure 1When the additional chalcogen precursor 106 is added to the reaction mixture containing the QD seeds 102. In some instances, the growth of the QD seeds 102 is quenched before the chalcogen precursor 106 is added. For example, the reaction mixture containing the QD seeds 102 can be reacted at a growth temperature (e.g., 150°C, 40 minutes) and then cooled to an ambient temperature (e.g., 25°C). Quenching can prevent uneven growth and agglomeration of the QD seeds 102. In another example, the chalcogen precursor 106 is added to the reaction mixture without quenching the growth of the QD seeds 102. For example, when the additional chalcogen precursor used to grow the infrared absorbing quantum dots 100 from the QD seeds 102 is substantially the same as the chalcogen precursor used to form the QD seeds 102, quenching can be omitted.

[0042] As described above, in some examples, infrared absorbing quantum dots 100 are formed by adding an additional amount of chalcogen precursor 106 to a reaction mixture containing QD seeds 102. In some examples, additional TOPTe is added to the reaction mixture containing QD seeds 102. In some examples, the reaction mixture is further heated to 1 hour. For example, the reaction mixture can be heated for 40 minutes to grow infrared absorbing quantum dots 100 from QD seeds 102. In other examples, the reaction mixture is heated for more than 1 hour.

[0043] In some examples, the infrared absorbing quantum dots 100 are grown at a temperature in the range of 80°C to 200°C. In another example, the infrared absorbing quantum dots 100 are grown at a temperature in the range of 120°C to 180°C. In another example, the infrared absorbing quantum dots 100 are grown at a temperature in the range of 140°C to 160°C. By growing the infrared absorbing quantum dots 100 from the QD seeds 102, the infrared absorbing quantum dots 100 can be formed with different absorbance peaks in the range of 1400nm to 1800nm ​​(e.g., with a peak to valley ratio (peak / valley) ≥ 1.0), which is difficult to achieve via a single step process. Figure 2 This is a transmission electron microscope (TEM) image showing Ag—Te-based infrared absorption quantum dots prepared as described in this specification.

[0044] An additional amount of chalcogen precursor 106 is added to achieve an appropriate molar ratio of Ag:Te (Ag / Te) in the infrared absorbing quantum dot 100. In some examples, the infrared absorbing quantum dot 100 includes a molar ratio of Ag:Te (Ag / Te) in the range of 2 to 6. In another example, the infrared absorbing quantum dot 100 includes a molar ratio of Ag:Te (Ag / Te) in the range of 2.1 to 5.8. In another example, the infrared absorbing quantum dot 100 includes a molar ratio of Ag:Te (Ag / Te) in the range of 2.1 to 2.7. Here, the molar ratio of Ag:Te (Ag / Te) can be calculated by ICP emission analysis.

[0045] Figure 3 is a graph showing the absorbance spectra of multiple quantum dot groups formed using different Ag:Te molar ratios (Ag / Te). The absorbance peak values ​​are also recorded in Table 1. Figure 3 As shown in Table 1, a quantum dot group with a molar ratio of Ag:Te of 3.4 has a clear absorbance peak centered at about 1150nm, and the peak-to-valley ratio (peak / valley) is 1.6. The peak-to-valley ratio (peak / valley) recorded in this specification refers to the ratio of the maximum absorbance value in the absorbance peak to the minimum absorbance value adjacent to the absorbance peak. In the case where the absorbance peak is adjacent to two valleys, the peak-to-valley ratio (peak / valley) is calculated using an absorbance value greater than the two valleys. Quantum dots with a molar ratio of Ag:Te of 3.2, 3.1, 2.5 and 2.1 were also prepared. Compared with quantum dots with a molar ratio of Ag:Te (Ag / Te) of 3.4, quantum dots with a molar ratio of Ag:Te (Ag / Te) of 3.2 show a wider absorbance peak in the range of 1100nm to 1200nm. The quantum dots with Ag:Te molar ratios (Ag / Te) of 3.1, 2.5, and 2.1 did not show clear absorbance peaks in the range of 1100 nm to 1200 nm.

[0046] In some examples, the infrared absorbing quantum dot 100 has an absorbance peak in the range of 1400nm to 1800nm, and the peak-to-valley ratio (peak / valley) of the absorbance peak is greater than 1.0. The greater the value of the peak-to-valley ratio (peak / valley), the more infrared light is absorbed. It can be considered that when the peak-to-valley ratio (peak / valley) is greater than 1.0, it has sufficient infrared absorption characteristics. From these viewpoints, the upper limit of the peak-to-valley ratio (peak / valley) is not particularly limited, for example, it can be less than 10.0. For example, Figure 3 As shown in Table 1, quantum dots having Ag:Te at a molar ratio of 2.5 showed an absorbance peak at more than 1400 nm, and the peak-to-valley ratio (peak / valley) exceeded 1.0. The absorbance peak was red-shifted by reducing the molar ratio of Ag:Te (Ag / Te) to 2.1.

[0047] Table 1 shows the absorbance peak wavelength (λmax), half width at half maximum (HWHM), and peak-to-valley ratio (peak / valley) of quantum dot groups formed in a manner to achieve different Ag:Te molar ratios (Ag / Te) (the Ag:Te molar ratio is an actual measured value based on ICP analysis).

[0048] [Table 1]

[0049]

[0050] In some examples, the infrared absorbing quantum dots may additionally or alternatively contain other chalcogens. For example, Figure 4 1 represents another example of an infrared absorbing quantum dot 108 further comprising selenium (Se). Figure 1 Similarly, the infrared absorbing quantum dots 100 Figure 4 The infrared absorbing quantum dots 108 are formed by a two-step seed growth process in which the QD seed crystal 102 functions as a basis for growing the infrared absorbing quantum dots 108. Figure 1 An additional amount of a chalcogen precursor 106 (e.g., TOPTe) is added to a reaction mixture containing a silver precursor 104 and a QD seed 102 together with a selenium precursor 110. The selenium precursor 110 may include any suitable material. As an example of a preferred selenium precursor 110, diphenylphosphine selenide (DPPSe) may be cited, but is not limited thereto. In this way, the resulting infrared absorbing quantum dots 108 include: a core containing Ag and Te (e.g., in the form of an Ag-Te type QD seed 102), and a shell 112 containing Ag, Te, and Se (e.g., in the form of an Ag-Se-Te type shell).

[0051] The infrared absorbing quantum dots 108 are grown in the reaction mixture for up to 1 hour. For example, the infrared absorbing quantum dots 108 can be grown for 40 minutes. In another example, the infrared absorbing quantum dots 108 grow for more than 1 hour. In some examples, the infrared absorbing quantum dots 108 are grown at a temperature in the range of 80°C to 200°C. In another example, the infrared absorbing quantum dots 108 are grown at a temperature in the range of 120°C to 180°C. In another example, the infrared absorbing quantum dots 108 are grown at a temperature in the range of 140°C to 160°C. By growing the infrared absorbing quantum dots 108 from the QD seed crystal 102, the infrared absorbing quantum dots 108 can be formed with a clear absorbance peak in the range of 1400nm to 1800nm ​​(for example, with a peak to valley ratio (peak / valley) ≥ 1.0). The greater the value of the peak to valley ratio (peak / valley), the more infrared light is absorbed. It is considered that when the peak-to-valley ratio (peak / valley) is 1.0 or more, sufficient infrared absorption characteristics are obtained. From these viewpoints, the upper limit of the peak-to-valley ratio (peak / valley) is not particularly limited, and may be, for example, 10.0 or less. Figure 5 The TEM image of Ag-Se-Te-based infrared absorption quantum dots prepared as described in this specification is shown.

[0052] The selenium precursor 110 is added to achieve an appropriate Se:Te molar ratio (Se / Te). In some instances, the infrared absorbing quantum dots 108 are prepared with a Se:Te molar ratio (Se / Te) of less than 0.20 and greater than 0.00. In some embodiments, the Se:Te molar ratio (Se / Te) is in the range of 0.01 to 0.20. In other embodiments, the Se:Te molar ratio (Se / Te) is in the range of 0.05 to 0.15. In another embodiment, the Se:Te molar ratio (Se / Te) is in the range of 0.077 to 0.135. As an example, samples of quantum dots having a Se:Te molar ratio (Se / Te) of 0.077 and 0.135 are prepared. Figure 6 A graph showing the absorbance spectra of multiple quantum dot groups formed using different Se:Te molar ratios (Se / Te). The values ​​of the absorbance peaks are also recorded in Table 2. In the absence of Se, an absorbance peak centered at 1522nm is obtained. When Se is added in a manner such that the molar ratio of Se:Te (Se / Te) is 0.077, the absorbance peak is blue-shifted to 1481nm. When the molar ratio of Se:Te (Se / Te) is 0.135, an absorbance peak centered at 1409nm with a peak-to-valley ratio (peak / valley) of 1.2 is obtained. Therefore, Se dopants can be used to adjust the absorbance of infrared absorbing quantum dots. When S is introduced on the basis of Se or as a substitute for Se, a result in which the absorbance is further blue-shifted relative to the Ag-Te-Se class can be obtained. In some instances, the absorbance can be further blue-shifted to 1200nm by increasing the molar ratio of Se:Te (Se / Te) to more than 0.20. It is also understood that infrared absorbing quantum dots can be prepared using Ag-Se-like shells without Te. In some examples, the shell can contain ZnS, ZnSe and / or other suitable materials, which have weaker environmental and health concerns.

[0053] Table 2 shows the λmax, HWHM, and peak-to-valley ratio (peak / valley) of quantum dot groups formed using different Se:Te molar ratios (Se / Te).

[0054] [Table 2]

[0055]

[0056] Furthermore, the presence of Se in the infrared absorbing quantum dots 108 can be confirmed by X-ray fluorescence (XRF) analysis. Figure 7The XRF spectrum obtained for the sample of the infrared absorbing quantum dot 108 is shown. In tetrachloroethylene (TCE) solvent, a sample having a Se:Te molar ratio (Se / Te) of 0.135 was prepared. This confirms that Se is introduced into the infrared absorbing quantum dot 108 .

[0057] Table 3 shows actual values ​​and theoretical molar ratios of Se:Te (Se / Te) measured by XRF analysis.

[0058] [Table 3]

[0059]

[0060] In some examples, the prepared infrared absorbing quantum dots can be dispersed in a non-polar solvent. For example, the infrared absorbing quantum dots 100, 108 can be purified from the reaction mixture and then dispersed in a non-polar solvent. As a suitable example of a non-polar solvent, tetrachloroethylene (TCE) can be cited, but it is not limited thereto.

[0061] In other examples, the infrared absorbing quantum dots can be dispersed in polar solvents. For example, a ligand exchange reaction can be performed to provide the infrared absorbing quantum dots with ligands that enable the quantum dots to be dispersed in polar solvents. The polar solvent can include any suitable solvent. The solvent can have a viscosity and surface tension suitable for inkjet printing. In this way, the infrared absorbing quantum dots can be used to quickly and cost-effectively manufacture IR absorbing devices such as pixels of IR detectors.

[0062] Reference here Figure 8 , which shows a flow chart of an example method 800 for making infrared absorbing quantum dots. Figure 1 to Figure 7 The components shown are used to provide a description of method 800, and reference is made to Figure 1 to Figure 7 The corresponding parts of the method 800 are used to illustrate the method steps in the method 800. It can be understood that the method 800 can also be implemented in other environments using other appropriate hardware and software components.

[0063] It is understood that the following description of method 800 is provided as an example and is not limiting. It is understood that various steps of method 800 may be omitted or performed in an order different from that described, and method 800 may include Figure 8 Additional steps and / or substitutions for the steps shown may be made without departing from the scope of the present invention.

[0064] Method 800 includes nucleating a QD seed crystal comprising Ag and Te at 802. For example, Figure 1The QD seed crystal 102 is nucleated using a silver precursor 104 and a chalcogen precursor 106 containing Te to form an Ag-Te type QD seed crystal. Figure 1 Infrared absorption quantum dots 100 and Figure 4 The infrared absorbing quantum dots 108 are used as the basis for growth.

[0065] In some examples, method 800 includes providing excess Ag at 804. For example, QD seeds 102 can be nucleated in the presence of excess Ag. Providing excess Ag, as with the stoichiometric ratio of Ag and Te in the QD seeds, can finely control the size and dispersion of the QD seeds.

[0066] Method 800 includes: in 806, adding a chalcogen precursor to grow a QD seed crystal, thereby forming an infrared absorption quantum dot having an absorbance peak in the range of 1400nm to 1800nm. The peak-to-valley ratio (peak / valley) of the absorbance peak of the infrared absorption quantum dot is greater than 1.0, and the chalcogen precursor includes Te. For example, Figure 1 The infrared absorption quantum dots 100 are generated by adding an additional amount of a chalcogen precursor 106 to a reaction mixture containing QD seed crystals 102. When the infrared absorption quantum dots 100 are grown from the QD seed crystals 102, an absorbance peak is obtained in the range of 1400 nm to 1800 nm, and the peak-to-valley ratio (peak / valley) of the absorbance peak is greater than 1.0.

[0067] In some instances, such as Figure 8 As shown in 808 in FIG. 1 , adding a chalcogen precursor further comprises: adding Se. For example, Figure 4 The infrared absorbing quantum dots 108 are formed by adding a Se precursor 110 to a reaction mixture containing QD seeds 102. Figure 7 This allows Se to be introduced into the infrared absorbing quantum dots 108 as shown in XRF.

[0068] In some examples, method 800 includes forming quantum dots at 810 with a molar ratio of Se:Te (Se / Te) of less than 0.20 and greater than 0.00. Figure 6 As mentioned above, Se dopants can be used to adjust the absorbance of infrared absorbing quantum dots. If a Se:Te molar ratio (Se / Te) of less than 0.20 is used, an absorbance peak in the range of 1400nm to 1800nm ​​is obtained when the peak-to-valley ratio (peak / valley) is ≥1.0. The larger the value of the peak-to-valley ratio (peak / valley), the more infrared light is absorbed. It can be considered that when the peak-to-valley ratio (peak / valley) is greater than 1.0, it has sufficient infrared absorption characteristics. From these viewpoints, the upper limit of the peak-to-valley ratio (peak / valley) is not particularly limited, for example, it can be less than 10.0.

[0069] In some examples, method 800 includes forming quantum dots at 812 with a molar ratio of Ag:Te (Ag / Te) in a range of 2.1 to 2.7. Figure 3 As described above, the absorbance of infrared absorbing quantum dots can be adjusted using the molar ratio of Ag:Te (Ag / Te). If the molar ratio of Ag:Te (Ag / Te) in the range of 2.1 to 2.7 is used, an absorbance peak in the range of 1400 nm to 1800 nm is obtained, and the ratio of peak to valley (peak / valley) is ≥ 1.0.

[0070] With respect to method 800, in some examples, forming a quantum dot at 814 includes: forming a core comprising Ag and Te; and forming a shell comprising Ag, Te, and Se. For example, forming Figure 4 The infrared absorbing quantum dot 108 includes: forming a core containing Ag and Te; and forming a shell containing Ag, Te and Se. As shown in 816, in some examples, forming the core includes: forming an Ag-Te type core, and forming the shell includes: forming an Ag-Se-Te type shell. For example, the infrared absorbing quantum dot 108 includes a core in the form of Ag-Te type and a shell in the form of Ag-Se-Te type. As described above, this brings about an absorbance peak in the range of 1400nm to 1800nm.

[0071] The above method can be used to generate infrared absorbing quantum dots. The infrared absorbing quantum dots contain an absorbance peak in the range of 1400nm to 1800nm. This enables the infrared absorbing quantum dots to detect IR light in the range of 1400nm to 1800nm ​​(for example, light emitted by a 1450nm laser) with a high signal-to-noise ratio. The peak-to-valley ratio (peak / valley) of the absorbance peak is greater than 1.0. This also increases the signal-to-noise ratio compared to using a material with a smaller peak-to-valley ratio (peak / valley). Furthermore, the infrared absorbing quantum dots contain silver and tellurium, and optionally selenium. In this way, the infrared absorbing quantum dots can be substantially free of heavy metal elements.

[0072] Another example provides infrared absorption quantum dots comprising silver and tellurium, the infrared absorption quantum dots comprising an absorbance peak in the range of 1400nm to 1800nm, and the peak to valley ratio (peak / valley) of the absorbance peak being 1.0 or more. In some such examples, the infrared absorption quantum dots are substantially free of heavy metal elements. In some such examples, the infrared absorption quantum dots alternatively or additionally have a molar ratio of Ag:Te (Ag / Te) in the range of 2.1 to 2.7. In some such examples, the infrared absorption quantum dots alternatively or additionally further comprise selenium. In some such examples, the infrared absorption quantum dots alternatively or additionally comprise: Se:Te molar ratio (Se / Te) is less than 0.20 and exceeds 0.00. In some such examples, the infrared absorption quantum dots according to embodiments of the present invention alternatively or additionally comprise: a core comprising Ag and Te and a shell comprising Ag, Te and Se. In some such examples, the core alternatively or additionally comprises an Ag-Te type form, and the shell alternatively or additionally comprises an Ag-Se-Te type form. In some such examples, the infrared absorbing quantum dots alternatively or additionally further comprise: a core comprising Ag and Te and a shell comprising Ag and Se. In some such examples, the infrared absorbing quantum dots alternatively or additionally can be dispersed in a non-polar solvent. In some such examples, the infrared absorbing quantum dots alternatively or additionally further comprise: a ligand that enables the quantum dots to be dispersed in a polar solvent.

[0073] Another example provides a method for manufacturing infrared absorption quantum dots, the method comprising: nucleating QD seeds comprising Ag and Te; adding a chalcogen precursor to grow the QD seeds, thereby forming infrared absorption quantum dots having an absorbance peak in the range of 1400nm to 1800nm. At this time, the peak-to-valley ratio (peak / valley) of the absorbance peak is greater than 1.0, and the chalcogen precursor comprises Te. In some such examples, adding the chalcogen precursor further comprises: adding Se. In some such examples, the method alternatively or additionally further comprises: forming infrared absorption quantum dots having a molar ratio (Se / Te) of Se:Te of less than 0.20 and greater than 0.00. In some such examples, the method alternatively or additionally comprises: providing an excess of Ag. In some such examples, the method alternatively or additionally comprises: forming infrared absorption quantum dots having a molar ratio (Ag / Te) of Ag:Te in the range of 2.1 to 2.7. In some such examples, forming the infrared absorbing quantum dots alternatively or additionally comprises: forming a core comprising Ag and Te; and forming a shell comprising Ag, Te and Se. In some such examples, forming the core alternatively or additionally comprises: forming an Ag-Te type core, and forming the shell comprises: forming an Ag-Se-Te type shell.

[0074] Another example provides an infrared absorbing quantum dot comprising a core comprising Ag and Te and a shell comprising Ag, Te and Se, the infrared absorbing quantum dot comprising an absorbance peak in the range of 1400 nm to 1800 nm, and the peak to valley ratio (peak / valley) of the absorbance peak is greater than 1.0. In some such examples, the molar ratio of Ag:Te (Ag / Te) is in the range of 2.1 to 2.7. In some such examples, the molar ratio of Se:Te (Se / Te) is less than 0.20 and exceeds 0.00.

[0075] The infrared absorption quantum dot and the method for producing the infrared absorption quantum dot according to the embodiment of the present invention include the following configurations.

[0076] (1) An infrared absorbing quantum dot comprising silver (Ag) and tellurium (Te), wherein:

[0077] The infrared absorption quantum dots include an absorbance peak in the range of 1400nm to 1800nm,

[0078] The peak-to-valley ratio (peak / valley) of the absorbance peak is 1.0 or more.

[0079] (2) The infrared absorbing quantum dot according to (1), wherein:

[0080] The infrared absorbing quantum dots are substantially free of heavy metal elements.

[0081] (3) The infrared absorbing quantum dot according to (1) or (2), wherein:

[0082] The molar ratio of Ag:Te (Ag / Te) is in the range of 2.1 to 2.7.

[0083] (4) The infrared absorbing quantum dot according to any one of (1) to (3), further comprising selenium (Se).

[0084] (5) The infrared absorbing quantum dot according to (4), wherein:

[0085] The molar ratio of Se:Te (Se / Te) is 0.20 or less and exceeds 0.00.

[0086] (6) The infrared absorbing quantum dot according to any one of (1) to (5), further comprising:

[0087] a core comprising Ag and Te; and

[0088] Shell containing Ag, Te and Se.

[0089] (7) The infrared absorbing quantum dot according to any one of (1) to (5), further comprising:

[0090] a core comprising Ag and Te; and

[0091] Shell containing Ag and Se.

[0092] (8) The infrared absorbing quantum dot according to any one of (1) to (7), wherein

[0093] The infrared absorbing quantum dots can be dispersed in a non-polar solvent.

[0094] (9) The infrared absorbing quantum dot according to any one of (1) to (7), further comprising:

[0095] A ligand that enables the infrared absorbing quantum dots to be dispersed in a polar solvent.

[0096] (10) A method for manufacturing infrared absorbing quantum dots, comprising:

[0097] a step of forming a core of a quantum dot seed crystal containing silver (Ag) and tellurium (Te); and

[0098] The process of forming infrared absorption quantum dots comprises adding a chalcogen precursor to grow quantum dot seed crystals, thereby forming infrared absorption quantum dots having an absorbance peak in the range of 1400nm to 1800nm,

[0099] The peak-to-valley ratio (peak / valley) of the absorbance peak is greater than 1.0,

[0100] The chalcogen precursor includes tellurium (Te).

[0101] (11) The method for producing infrared absorbing quantum dots according to (10), wherein:

[0102] The step of adding a chalcogen precursor further includes adding selenium (Se).

[0103] (12) The method for producing infrared absorbing quantum dots according to (11), further comprising:

[0104] The infrared absorption quantum dots are formed so that the molar ratio of Se:Te (Se / Te) is 0.20 or less and exceeds 0.00.

[0105] (13) The method for producing infrared absorption quantum dots according to any one of (10) to (12), further comprising:

[0106] An excess of Ag was provided.

[0107] (14) The method for producing infrared absorption quantum dots according to any one of (10) to (13), further comprising:

[0108] The infrared absorption quantum dots are formed so that the molar ratio of Ag:Te (Ag / Te) is in the range of 2.1 to 2.7.

[0109] (15) The method for producing infrared absorption quantum dots according to any one of (11) to (14), further comprising:

[0110] forming a core comprising Ag and Te; and

[0111] A shell containing Ag, Te and Se is formed.

[0112] (16) An infrared absorbing quantum dot comprising: a core containing silver (Ag) and tellurium (Te), and a shell containing silver (Ag), tellurium (Te) and selenium (Se), wherein:

[0113] The infrared absorption quantum dots include an absorbance peak in the range of 1400nm to 1800nm,

[0114] The peak-to-valley ratio (peak / valley) of the absorbance peak is 1.0 or more.

[0115] (17) The infrared absorbing quantum dot according to (16), wherein:

[0116] The molar ratio of Ag:Te (Ag / Te) is in the range of 2.1 to 2.7.

[0117] (18) The infrared absorbing quantum dot according to (16) or (17), wherein:

[0118] The molar ratio of Se:Te (Se / Te) is 0.20 or less and exceeds 0.00.

[0119] The configurations and / or methods described in this specification are illustrative in nature and can be subjected to various modifications. Therefore, it should be understood that these specific implementations or embodiments should not be considered in a limiting sense. The specific procedures or methods described in this specification may represent one or more of any number of strategies. Therefore, the various actions illustrated and / or described may be implemented in the order illustrated and / or described, in other orders, in parallel or in an omitted order. Similarly, the order of the described processes may be changed.

[0120] The subject matter of the present invention includes all novel and non-obvious combinations and sub-combinations of the various processes, systems and compositions, and other features, functions, acts and / or properties disclosed in this specification, and any and all equivalents thereof.

[0121] Furthermore, the use of “includes,” “including,” “has,” “contains,” variations thereof, and other similar terms in any of the detailed description or claims does not exclude any additional or other elements, but is intended to be inclusive in the same manner as the term “comprising” which is an open transition term.

[0122] When "and / or" is used in this specification, it is defined collectively or as follows as specified by the following truth table (Table 4).

[0123] [Table 4]

[0124]

[0125] Example

[0126] The following paragraphs describe examples of infrared absorbing quantum dots prepared as described in the specification and quantum dots based on comparative examples. Table 5 summarizes the composition and optical properties (λmax, HWHM, peak / valley) of each quantum dot population.

[0127] [Table 5]

[0128]

[0129] [Example 1]~[Example 3]

[0130] Ag-Te-based QD seeds were nucleated by the hot injection method. Specifically, TOPTe was injected into a Ag (acetate) solution mixed with octanethiol at 150°C. The temperature was maintained at 150°C for 40 minutes, and then the reaction mixture was cooled to ambient temperature. The molar ratio of Ag:Te (Ag / Te) at the time of addition was 5.8. The resulting QD seeds had an absorbance peak at 1150nm, and a peak-to-valley ratio (peak / valley) of 1.6.

[0131] Using the Ag-Te-based QD seed crystals synthesized as described above, the infrared absorption quantum dots of Example 1 were prepared. In order to adjust the molar ratio of Ag:Te (Ag / Te), TOPTe was added at 150°C and the growth of infrared absorption quantum dots was further carried out for 40 minutes. The infrared absorption quantum dots were purified using acetone as an antisolvent and precipitated by centrifugation. Next, the infrared absorption quantum dots were recovered, redispersed in TCE, and centrifuged again to remove undissolved particles. Next, the infrared absorption quantum dots were analyzed using an ultraviolet visible near infrared (UV-Vis-NIR) spectrophotometer. In addition, elemental analysis was performed on the obtained infrared absorption quantum dots.

[0132] The elemental analysis was performed as follows. First, 0.05 g to 0.2 g of infrared absorbing quantum dots in an organic solvent were mixed with 10 mL of concentrated nitric acid and kept at 200 ° C for 15 minutes. Then, after decomposing the infrared absorbing quantum dots using a microwave decomposer (CEM Mars6), the sample was diluted to 50 mL with deionized water to obtain a sample for elemental analysis. In addition, ICP-OES (Agilent 5800) was used to implement an external calibration curve using commercially available certified element standards. At this time, in order to correct the drift of the equipment, an internal standard was used in the calibration standard and the sample.

[0133] In Example 1 and Example 2, the infrared absorbing quantum dots with a molar ratio of Ag:Te (Ag / Te) of 2.4 were adjusted. These brought an absorbance peak having a peak-to-valley ratio (peak / valley) exceeding 1.0 on the long wavelength side of 1500 nm.

[0134] In Example 3, by reducing the molar ratio of Ag:Te (Ag / Te) to 2.1, the absorbance peak was red-shifted to 1726 nm.

[0135] [Example 4], [Example 5]

[0136] The infrared absorbing quantum dots of Examples 4 and 5 were prepared using the Ag-Te-based QD seeds synthesized by Example 1. Specifically, a mixture of TOPTe and DPPSe was injected into the mixture of Ag-Te-based QD seeds at 150°C. For the mixture of TOPTe and DPPSe, the molar ratio of Se:Te (Se / Te) was made 0.077 in Example 4, and the molar ratio of Se:Te (Se / Te) was made 0.135 in Example 5. The temperature of the mixture was maintained for 40 minutes to form a shell of Ag-Se-Te-based (Te doped with Se) on the Ag-Te-based QD seeds. Next, the mixture was cooled to ambient temperature, the infrared absorbing quantum dots were purified, and the characteristics were determined as described above. In Example 4 (Se / Te=0.077), an absorbance peak was observed at 1481nm with a peak to valley ratio (peak / valley) exceeding 1.2. By increasing the molar ratio of Se:Te (Se / Te) to 0.135, the absorbance peak in Example 5 was blue-shifted to 1409 nm.

[0137] [Comparative Example 1]

[0138] In Comparative Example 1, Ag-Te quantum dots having a molar ratio of Ag:Te (Ag / Te) of 3.4 were prepared. The quantum dots of Comparative Example 1 had an absorbance peak at 1149 nm, and a peak-to-valley ratio (peak / valley) of 1.6, similarly to the Ag-Te QD seed crystals described above.

[0139] [Comparative Example 2]

[0140] In Comparative Example 2, the molar ratio of Ag:Te (Ag / Te) was reduced to 3.2. As a result, the same absorbance peak as in Comparative Example 1 at 1156 nm was obtained, but the ratio of the peak to the valley (peak / valley) was less than 1.3.

[0141] [Comparative Example 3]

[0142] In Comparative Example 3, the molar ratio of Ag:Te (Ag / Te) was reduced to 3.1. In this case, no identifiable absorbance peak was observed.

[0143] [Comparative Example 4]

[0144] In Comparative Example 4, DPPSe was used instead of TOPTe to prepare Ag-Se-based quantum dots as described above. The obtained Ag-Se-based quantum dots had an absorbance peak at 960 nm.

[0145] [Comparative Example 5]

[0146] The Ag-S quantum dots prepared in Comparative Example 5 are blue-shifted relative to the Ag-Se quantum dots prepared in Comparative Example 4, and have an absorbance peak at 800 nm.

[0147] Explanation of symbols

[0148] 100 Infrared Absorption Quantum Dots

[0149] 102 QD Seed

[0150] 104 Silver Precursor

[0151] 106 Chalcogen Precursors

[0152] 108 Infrared Absorption Quantum Dots

[0153] 110 Selenium Precursor

[0154] 112 Shell

Claims

1. An infrared absorbing quantum dot comprising silver (Ag) and tellurium (Te), wherein: The infrared absorption quantum dots include an absorbance peak in the range of 1400nm to 1800nm, The peak-to-valley ratio (peak / valley) of the absorbance peak is 1.0 or more.

2. The infrared absorption quantum dot according to claim 1, wherein The infrared absorbing quantum dots are substantially free of heavy metal elements.

3. The infrared absorption quantum dot according to claim 1 or 2, wherein: The molar ratio of Ag:Te (Ag / Te) is in the range of 2.1 to 2.

7. 4 . The infrared absorbing quantum dot according to claim 1 , further comprising selenium (Se).

5. The infrared absorption quantum dot according to claim 4, wherein: The molar ratio of Se:Te (Se / Te) is 0.20 or less and exceeds 0.

00.

6. The infrared absorption quantum dot according to any one of claims 1 to 5, further comprising: a core comprising Ag and Te; and Shell containing Ag, Te and Se.

7. The infrared absorption quantum dot according to any one of claims 1 to 5, further comprising: a core comprising Ag and Te; and Shell containing Ag and Se.

8. The infrared absorption quantum dot according to any one of claims 1 to 7, wherein The infrared absorbing quantum dots can be dispersed in a non-polar solvent.

9. The infrared absorption quantum dot according to any one of claims 1 to 7, further comprising: A ligand that enables the infrared absorbing quantum dots to be dispersed in a polar solvent.

10. A method for manufacturing infrared absorbing quantum dots, comprising: a step of forming a core of a quantum dot seed crystal containing silver (Ag) and tellurium (Te); and The process of forming infrared absorption quantum dots comprises adding a chalcogen precursor to grow quantum dot seed crystals, thereby forming infrared absorption quantum dots having an absorbance peak in the range of 1400nm to 1800nm, The peak-to-valley ratio (peak / valley) of the absorbance peak is greater than 1.0, The chalcogen precursor includes tellurium (Te).

11. The method for producing infrared absorption quantum dots according to claim 10, wherein: The step of adding a chalcogen precursor further includes adding selenium (Se).

12. The method for producing infrared absorbing quantum dots according to claim 11, further comprising: The infrared absorption quantum dots are formed so that the molar ratio of Se:Te (Se / Te) is 0.20 or less and exceeds 0.

00.

13. The method for producing infrared absorption quantum dots according to any one of claims 10 to 12, further comprising: An excess of Ag was provided.

14. The method for producing infrared absorption quantum dots according to any one of claims 10 to 13, further comprising: The infrared absorption quantum dots are formed so that the molar ratio of Ag:Te (Ag / Te) is in the range of 2.1 to 2.

7.

15. The method for producing infrared absorption quantum dots according to any one of claims 11 to 14, further comprising: forming a core comprising Ag and Te; and A shell containing Ag, Te and Se is formed.

16. An infrared absorbing quantum dot comprising: a core containing silver (Ag) and tellurium (Te), and a shell containing silver (Ag), tellurium (Te) and selenium (Se), wherein: The infrared absorption quantum dots include an absorbance peak in the range of 1400nm to 1800nm, The peak-to-valley ratio (peak / valley) of the absorbance peak is 1.0 or more.

17. The infrared absorption quantum dot according to claim 16, wherein: The molar ratio of Ag:Te (Ag / Te) is in the range of 2.1 to 2.

7.

18. The infrared absorption quantum dot according to claim 16 or 17, wherein: The molar ratio of Se:Te (Se / Te) is 0.20 or less and exceeds 0.00.

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