Near-infrared luminous ytterbium-doped quantum dot material as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of light-emitting materials, and particularly relates to a near-infrared light-emitting ytterbium-doped quantum dot material and a preparation method and application thereof. According to the preparation method of the near-infrared light-emitting ytterbium-doped quantum dot material, a Yb-doped perovskite quantum dot synthesis method which is high in near-infrared light-emitting intensity, good in stability and simple in preparation is innovatively provided, short-chain amine is used in the preparation process, and the near-infrared light-emitting ytterbium-doped quantum dot material has high reaction activity, small steric hindrance and high near-infrared light-emitting efficiency. The complex ability with precursor raw materials is low, chemical bonds between halogen and metal ions are easy to open in the reaction process, and the complex is matched with long-chain amine (such as oleylamine and the like) in a perovskite quantum dot system prepared by a conventional injection method, so that doping of rare earth Yb ions is facilitated, the Yb ions smoothly enter perovskite crystal lattices, and the perovskite quantum dot is prepared. The near-infrared luminous intensity of the material is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of luminescent materials, and in particular relates to a near-infrared luminescent ytterbium-doped quantum dot material and a preparation method and application thereof. Background Art

[0002] In recent years, as a new type of semiconductor material, perovskite has demonstrated its excellent capabilities and application prospects in many fields such as solar cells, light-emitting diodes, detectors, lasers, display panels, etc. Among them, perovskite luminescent materials, especially lead-based perovskite quantum dots (APbX3, where A can represent cesium, formamidine or methylamine; X can represent chlorine, bromine or iodine), have attracted widespread attention since Protesescu et al. invented and synthesized them in 2015 due to their narrow half-peak width, high quantum yield, high luminescent color purity, and adjustable luminescent peak position. As an ionic crystal, the internal bond energy of the perovskite lattice is low, and the intrinsic luminescence of perovskite or metal ions can be improved by doping with a variety of metal ions. At the same time, due to its large absorption cross section, it can be used as an excellent matrix material for rare earth ions to achieve high-efficiency rare earth ion 4f level radiation luminescence.

[0003] Among many rare earth elements, Yb doping into perovskite quantum dots can achieve near-infrared luminescence at its intrinsic 980nm peak. At the same time, selecting the appropriate perovskite quantum dot band gap width can introduce a unique quantum tailoring effect, showing great application prospects in near-infrared light-emitting devices and photovoltaic gain devices. Yb ions replace Pb ions at the B position in perovskite to achieve the doping effect, but the difference in the radii of Yb and Pb ions is large and is close to the doping tolerance limit of perovskite materials, resulting in the need for higher temperatures to achieve effective doping. At the same time, due to the different bond energies and solubilities of Pb, Yb precursors and compounds, the near-infrared luminescence of Yb-doped perovskite quantum dots is weak.

[0004] In view of this, it is necessary to develop a suitable preparation method to achieve effective doping of Yb ions and thereby enhance the near-infrared luminescence intensity of quantum dots. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defects of the prior art such as the difficulty in doping Yb into perovskite quantum dots and the weak near-infrared luminescence of the material, thereby providing a near-infrared luminescent ytterbium-doped quantum dot material and its preparation method and application.

[0006] To this end, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a near-infrared luminescent ytterbium-doped quantum dot material, comprising the following steps: injecting a cesium-containing precursor solution into a lead- and ytterbium-containing precursor solution for reaction;

[0008] The lead and ytterbium-containing precursor solution includes short-chain amines and long-chain amines, wherein the total number of carbon chain atoms M of the short-chain amines satisfies 6≤M≤12, and the total number of carbon chain atoms N≥16 of the long-chain amines.

[0009] Optionally, the volume ratio of the short-chain amine to the long-chain amine is (0.66-1.5):1; in the present invention, the volume ratio here refers to the volume ratio at room temperature, and room temperature generally corresponds to 25°C.

[0010] And / or, the short-chain amine includes C6~C 12 and / or, the long-chain amine comprises oleylamine.

[0011] In the present invention, C6~C 12 The alkylamines include alkylamines with a total chain length (which may contain branched structures) and a carbon number between 6 and 12, such as octylamine, isooctylamine, n-hexylamine, dodecylamine, and the like.

[0012] Optionally, the total number of carbon atoms of the long-chain amine is 16-19.

[0013] In the present invention, the long-chain amine may be an alkylamine or an alkenylamine, for example, oleylamine, heptadecenylamine, nonadecenylamine, octadecylamine, and the like.

[0014] Optionally, the lead and ytterbium-containing precursor solution also includes a supplementary halogen source.

[0015] Optionally, the supplementary halogen source includes at least one of oleylamine chloride, oleylamine bromide, octylamine chloride, octylamine bromide, trimethylbromosilane, and trimethylchlorosilane.

[0016] Optionally, the lead and ytterbium-containing precursor solution further includes a solvent.

[0017] Optionally, the co-solvent includes at least one of methanol, ethanol and propanol.

[0018] Optionally, the reaction temperature is 240-270° C., and the reaction time is greater than 5 s.

[0019] Optionally, the reaction time is 5 to 100 s.

[0020] Optionally, the step of preparing the cesium-containing precursor solution includes: mixing a cesium source with oleic acid and octadecene, and dissolving them.

[0021] Optionally, the cesium source includes at least one of cesium carbonate and cesium acetate.

[0022] And / or, in the cesium-containing precursor solution, the concentration of the cesium source is 0.1 to 0.3 mol / L, calculated as cesium ions.

[0023] Optionally, the method for preparing the lead and ytterbium-containing precursor solution comprises: mixing and dissolving a lead source, an ytterbium source, a halogen source and / or a supplementary halogen source, a short-chain amine, a long-chain amine, oleic acid and octadecene.

[0024] Optionally, the lead source includes at least one of lead chloride, lead bromide, lead acetate, lead oxide, lead stearate, and lead oleate.

[0025] Optionally, the ytterbium source includes at least one of ytterbium chloride, ytterbium bromide, ytterbium acetate, and ytterbium oleate.

[0026] Optionally, the halogen source includes at least one of oleylamine chloride, oleylamine bromide, octylamine chloride, octylamine bromide, trimethylbromosilane, and trimethylchlorosilane.

[0027] Optionally, in the reaction system, the concentration of the lead source is 0.01 to 0.05 mol / L.

[0028] And / or, the concentration of the ytterbium source is 0.5 to 4 times the concentration of the lead source.

[0029] And / or, the concentration of total halogen ions is 3.5 to 14 times the concentration of the lead source.

[0030] And / or, the concentration of the cesium source is 0.3 to 1 times the concentration of the lead source in terms of cesium ions.

[0031] And / or, the bromine / chloride ion ratio is 0 to 0.2.

[0032] And / or, the concentration of the short-chain amine is 10 to 50 times the concentration of the lead source.

[0033] The present invention also provides a near-infrared luminescent ytterbium-doped quantum dot material prepared by the above preparation method.

[0034] The present invention also provides an application of the above-mentioned near-infrared luminescent ytterbium-doped quantum dot material in the fields of solar cells, light-emitting diodes, detectors, lasers, and display panels.

[0035] Specifically, the method for preparing the near-infrared luminescent ytterbium-doped quantum dot material provided by the present invention may include the following steps:

[0036] An appropriate amount of cesium carbonate powder is mixed with oleic acid and octadecene and heated to dissolve under vacuum to obtain a clear and transparent cesium oleate precursor.

[0037] Add appropriate amounts of lead source, ytterbium source, halogen source and short-chain amine (e.g. C6~C 12 Alkylamine) and long-chain amine (such as oleylamine), oleic acid, and octadecene are mixed and dissolved in a vacuum environment, and then under the protection of an inert gas, a cesium oleate precursor is injected, the reaction is fully reacted and cooled, and the precipitate is collected and centrifuged to obtain ytterbium-doped perovskite quantum dots.

[0038] In the present invention, the lead source can be selected from one of lead chloride, lead bromide, lead acetate, lead oxide, lead stearate, and lead oleate, the ytterbium source can be selected from one of ytterbium chloride, ytterbium bromide, ytterbium acetate, and ytterbium oleate, and the supplementary halogen source can be selected from one of oleylamine chloride, oleylamine bromide, octylamine chloride, octylamine bromide, trimethylbromosilane, and trimethylchlorosilane. Preferably, the concentration of the lead source in the reactants is 0.01 to 0.05 mol / L, the concentration of the ytterbium source is between 0.5 and 4 times the concentration of the lead source, the concentration of total halogen ions is between 3.5 and 14 times the concentration of the lead source, the ratio of bromine / chloride ions is between 0 and 0.2, the concentration of cesium oleate is between 0.3 and 1 times the concentration of the lead source, and the volume ratio of the short-chain amine ligand to oleylamine is between (0.66 to 1.5):1.

[0039] The technical solution of the present invention has the following advantages:

[0040] The invention provides a method for preparing a near-infrared luminescent ytterbium-doped quantum dot material, and innovatively proposes a method for synthesizing Yb-doped perovskite quantum dots with high near-infrared luminescence intensity, good stability and simple preparation. In the preparation process, short-chain amines are used, which have high reactivity, small steric hindrance, low complexing ability with precursor raw materials, and are easy to open the chemical bonds with halogen and metal ions during the reaction. In combination with long-chain amines (such as oleylamine, etc.) in the conventional injection method for preparing perovskite quantum dot systems, the doping of rare earth Yb ions is facilitated, and the Yb ions are smoothly introduced into the perovskite lattice, thereby improving the near-infrared luminescence intensity of the material.

[0041] The method for preparing the near-infrared luminescent ytterbium-doped quantum dot material provided by the present invention is based on the volume ratio of the short-chain amine to the long-chain amine and the specific definition of the short-chain amine and the long-chain amine, for example, C6-C 12 The combination of alkylamine and oleylamine can further enhance the near-infrared luminescence intensity of the material. 12 The alkyl amine is combined with the conventional hot injection system. The lead / ytterbium in the lead and ytterbium precursor solution will react with the halogen ions to form a halide precursor. The short-chain amines and long-chain amines in the solution usually form complexes with YbX3 and PbX2 to promote the dissolution of the precursor and participate in the final reaction. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1is the fluorescence spectrum of the ytterbium-doped quantum dots obtained in Example 1 of the present invention;

[0044] Figure 2 is the fluorescence spectrum of the ytterbium-doped quantum dots obtained in Example 2 of the present invention;

[0045] Figure 3 is the fluorescence spectrum of the ytterbium-doped quantum dots obtained in Comparative Example 1 of the present invention;

[0046] Figure 4 is the fluorescence spectrum of the ytterbium-doped quantum dots obtained in Comparative Example 2 of the present invention;

[0047] Figure 5 is the fluorescence spectrum of the ytterbium-doped quantum dots obtained in Comparative Example 2 of the present invention;

[0048] Figure 6 It is a diagram of the near-infrared and visible light photoluminescence quantum efficiency of the quantum dots obtained in Examples 1 and 2 of the present invention and Comparative Examples 1 and 2. DETAILED DESCRIPTION

[0049] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0050] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0051] The present invention provides a method for preparing a near-infrared luminescent ytterbium-doped quantum dot material, comprising the following steps: injecting a cesium-containing precursor solution into a lead- and ytterbium-containing precursor solution for reaction;

[0052] The lead and ytterbium-containing precursor solution includes short-chain amines and long-chain amines, wherein the total number of carbon chain atoms M of the short-chain amines satisfies 6≤M≤12, and the total number of carbon chain atoms N≥16 of the long-chain amines.

[0053] In some embodiments, the volume ratio of the short-chain amine to the long-chain amine is (0.66-1.5):1; for example, the volume ratio of the short-chain amine to the long-chain amine is 0.66:1, 0.7:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1, 0.95:1, 1:1, 1.05:1, 1.1:1, 1.15:1, 1.2:1, 1.25:1, 1.35:1, 1.4:1, 1.45:1 or 1.5:1, etc.

[0054] In the present invention, the volume ratio here refers to the volume ratio at room temperature, and room temperature generally corresponds to 25°C.

[0055] In some embodiments, the short chain amine is C6 to C 12 The alkylamine of C6~C 12 The alkylamine may refer to an alkylamine with a total chain length (may contain branched structures) and a carbon number between 6 and 12, for example, octylamine, isooctylamine, n-hexylamine, dodecylamine, and the like.

[0056] In some embodiments, the total number of carbon atoms of the long-chain amine is 16-19.

[0057] In some embodiments, the long-chain amine may be an alkylamine or an alkenylamine, for example, oleylamine, heptadecenylamine, nonadecenylamine, octadecylamine, and the like.

[0058] In some preferred embodiments, the short-chain amine includes C6 to C 12 and / or, the long-chain amine comprises oleylamine.

[0059] In some embodiments, the lead and ytterbium containing precursor solution further includes a supplemental halogen source.

[0060] In some embodiments, the supplemental halogen source includes at least one of oleylamine chloride, oleylamine bromide, octylamine chloride, octylamine bromide, trimethylsilyl bromide, and trimethylsilyl chloride.

[0061] In some embodiments, the lead and ytterbium-containing precursor solution further includes a co-solvent.

[0062] In some embodiments, the co-solvent includes at least one of methanol, ethanol, and propanol.

[0063] In some embodiments, the reaction temperature is 240-270°C, and the reaction time is greater than 5 seconds; alternatively, the reaction time is 5-100 seconds. For example, the reaction temperature may be 240°C, 245°C, 250°C, 255°C, 260°C, 265°C or 270°C, etc.; the reaction time may be 5 seconds, 10 seconds, 20 seconds, 30 seconds, 40 seconds, 50 seconds, 60 seconds, 70 seconds, 80 seconds, 90 seconds or 100 seconds, etc.

[0064] In some embodiments, the step of preparing the cesium-containing precursor solution includes: mixing and dissolving a cesium source with oleic acid and octadecene.

[0065] In some embodiments, the cesium source includes at least one of cesium carbonate and cesium acetate.

[0066] In some embodiments, the concentration of the cesium source in the cesium-containing precursor solution is 0.1 to 0.3 mol / L, calculated as cesium ions.

[0067] In some embodiments, the method for preparing the lead and ytterbium-containing precursor solution includes: mixing and dissolving a lead source, an ytterbium source, a halogen source and / or a supplementary halogen source, a short-chain amine, a long-chain amine, oleic acid and octadecene.

[0068] In some embodiments, the lead source includes at least one of lead chloride, lead bromide, lead acetate, lead oxide, lead stearate, and lead oleate.

[0069] In some embodiments, the ytterbium source includes at least one of ytterbium chloride, ytterbium bromide, ytterbium acetate, and ytterbium oleate.

[0070] In some embodiments, the halogen source includes at least one of oleylamine chloride, oleylamine bromide, octylamine chloride, octylamine bromide, trimethylsilyl bromide, and trimethylsilyl chloride.

[0071] In some embodiments, in the reaction system, the concentration of the lead source is 0.01 to 0.05 mol / L; for example, in the reaction system, the concentration of the lead source is 0.01 mol / L, 0.02 mol / L, 0.03 mol / L, 0.04 mol / L or 0.05 mol / L, etc.

[0072] In some embodiments, the concentration of the ytterbium source is 0.5 to 4 times the concentration of the lead source; for example, the concentration of the ytterbium source is 0.5, 1, 1.5, 2, 2.5, 3, 3.5 or 4 times the concentration of the lead source.

[0073] In some embodiments, the concentration of total halogen ions is 3.5 to 14 times the concentration of the lead source; for example, the concentration of total halogen ions is 3.5, 4, 5, 6, 8, 10, 12, 13 or 14 times the concentration of the lead source.

[0074] In some embodiments, the concentration of the cesium source is 0.3 to 1 times the concentration of the lead source, calculated as cesium ions; for example, the concentration of the cesium source is 0.3, 0.5, 0.6, 0.7, 0.9 or 1 times the concentration of the lead source, calculated as cesium ions.

[0075] In some embodiments, the bromine / chloride ion ratio is 0 to 0.2; for example, the bromine / chloride ion ratio is 0 (i.e., no bromide ions are contained), and the bromine / chloride ion ratio can also be 0.02, 0.04, 0.06, 0.08, 0.1, 0.12, 0.14, 0.15, 0.17, 0.19 or 0.2, etc.

[0076] In some embodiments, the concentration of the short chain amine is 10 to 50 times the concentration of the lead source. For example, the concentration of the short chain amine is 10, 12, 15, 18, 20, 25, 30, 35, 40, 45, or 50 times the concentration of the lead source.

[0077] The present invention also provides a near-infrared luminescent ytterbium-doped quantum dot material prepared by the above preparation method.

[0078] The present invention also provides an application of the above-mentioned near-infrared luminescent ytterbium-doped quantum dot material in the fields of solar cells, light-emitting diodes, detectors, lasers, and display panels.

[0079] Some embodiments and experimental test results are shown below:

[0080] Example 1

[0081] This embodiment provides a synthesis of CsPbCl3:Yb perovskite quantum dots, and the specific preparation steps and parameters are as follows:

[0082] Preparation of cesium oleate precursor:

[0083] Dissolve 0.8 g of Cs2CO3 powder in 3 mL of oleic acid and 30 mL of octadecene. Place the mixture in a 100 mL three-necked flask and heat to 120 degrees under vacuum for 60 min until the powder is completely dissolved.

[0084] Synthesis of CsPbCl3:Yb perovskite quantum dots

[0085] 0.3mmol of PbCl2 and 0.15mmol of YbCl3·6H2O were dissolved in 10mL of octadecene, 1.3mL of oleic acid, 0.625mL of oleylamine, 0.625mL of octylamine and 0.5mL of methanol, with methanol as a cosolvent. The mixture was placed in a 100mL three-necked flask and placed on a magnetic stirring heating mantle. After stirring and dissolving at 30 degrees for 10 minutes, it was heated to 120 degrees under vacuum and kept for 30 minutes to completely dissolve the drug. After the drug was completely dissolved, the temperature was raised to 250 degrees under a nitrogen environment, and 1mL of cesium oleate precursor solution was quickly injected, reacted for 10 seconds, and cooled with ice water. The obtained product was centrifuged at 5000rpm for 5min, the supernatant was discarded, the precipitate was redispersed in 10mL of toluene solution and shaken well, and the upper liquid was obtained by centrifugation at 8000rpm for 5min, the supernatant was discarded, the precipitate was redispersed in 5mL of n-hexane solution and shaken well, and then allowed to stand for use. The obtained near-infrared luminescence spectrum of CsPbCl3:Yb perovskite quantum dots is as follows Figure 1 shown.

[0086] Example 2

[0087] This embodiment provides a CsPbCl 2.7 Br 0.3 : Synthesis of Yb perovskite quantum dots, the specific preparation steps and parameters are as follows:

[0088] Preparation of cesium oleate precursor:

[0089] Dissolve 0.8 g of Cs2CO3 powder in 3 mL of oleic acid and 30 mL of octadecene. Place the mixture in a 100 mL three-necked flask and heat to 120 degrees under vacuum for 60 min until the powder is completely dissolved.

[0090] Preparation of Oleylamine Bromide Precursor

[0091] Mix 0.5 mL of 48% hydrobromic acid solution with 17.5 mL of oleylamine, place the mixture in a 100 mL three-necked flask, and heat to 120 degrees in vacuum for 30 minutes to obtain a light yellow transparent solution for use.

[0092] Synthesis of CsPbCl 2.7 B 0.3 :Yb perovskite quantum dots

[0093] 0.25mmol of Pb(OAc)2·3H2O and 0.5mmol of YbCl3·6H2O, 165uL of oleylamine bromide were dissolved in 10mL of octadecene, 2mL of oleic acid, 0.75mL of oleylamine, 0.75mL of octylamine and 1.5mL of methanol, where methanol was used as a cosolvent. The mixture was placed in a 100mL three-necked flask and placed on a magnetic stirring heating mantle, heated to 120 degrees under vacuum for 30min to completely dissolve the drug. After the drug was completely dissolved, the temperature was raised to 250 degrees under a nitrogen environment, and 1mL of cesium oleate precursor solution was quickly injected, reacted for 10s, and cooled with ice water. The obtained product was centrifuged at 5000rpm for 5min, the supernatant was discarded, the precipitate was redispersed in 10mL of toluene solution and shaken, and the upper liquid was obtained by centrifugation at 8000rpm for 5min, the supernatant was discarded, the precipitate was redispersed in 5mL of n-hexane solution and shaken, and then left to stand for use. The obtained CsPbCl 2.7 B 0.3 :Near-infrared luminescence spectrum of Yb perovskite quantum dots Figure 2 shown.

[0094] Example 3

[0095] This embodiment provides a synthesis of CsPbCl3:Yb perovskite quantum dots. Compared with Embodiment 1, the only difference is that an equal volume of n-hexylamine is used instead of octylamine.

[0096] Example 4

[0097] This embodiment provides a synthesis of CsPbCl3:Yb perovskite quantum dots. Compared with Embodiment 1, the only difference is that an equal volume of n-dodecylamine is used instead of octylamine.

[0098] Example 5

[0099] This embodiment provides a CsPbCl2.7 B 0.3 : The synthesis of Yb perovskite quantum dots is different from that of Example 2, except that the amount of octylamine used is 0.5 mL.

[0100] Example 6

[0101] This embodiment provides a CsPbCl 2.7 B 0.3 : The synthesis of Yb perovskite quantum dots is different from that of Example 2 except that the synthesis of CsPbCl 2.7 B 0.3 : In the Yb perovskite quantum dot step, the amount of oleylamine used is 0.5 mL.

[0102] Example 7

[0103] This embodiment provides a synthesis of CsPbCl3:Yb perovskite quantum dots. Compared with Example 1, the only difference is that an equal mass of cesium acetate is used instead of cesium carbonate.

[0104] Example 8

[0105] This embodiment provides a synthesis of CsPbCl3:Yb perovskite quantum dots. Compared with Example 1, the only difference is that in the step of synthesizing CsPbCl3:Yb perovskite quantum dots, the reaction temperature is 260°C and the reaction time is 20s.

[0106] Example 9

[0107] This embodiment provides a synthesis of CsPbCl3:Yb perovskite quantum dots. Compared with Example 1, the only difference is that ytterbium oleate is used in an equal molar amount instead of YbCl3·6H2O, and trimethylchlorosilane is added at a molar ratio of ytterbium oleate to trimethylchlorosilane of 1:3.

[0108] Comparative Example 1

[0109] This comparative example provides a synthesis of CsPbCl3:Yb perovskite quantum dots. Compared with Example 1, the only difference is that an equal volume of oleylamine is used instead of octylamine. The near-infrared luminescence spectrum of the obtained CsPbCl3:Yb perovskite quantum dots is as follows: Figure 3 shown.

[0110] Comparative Example 2

[0111] This comparative example provides a synthesis of CsPbCl3:Yb perovskite quantum dots. Compared with Example 1, the only difference is that an equal volume of octylamine is used instead of oleylamine. The near-infrared luminescence spectrum of the obtained CsPbCl3:Yb perovskite quantum dots is as follows: Figure 4 shown.

[0112] Comparative Example 3

[0113] This comparative example provides a synthesis of CsPbCl3:Yb perovskite quantum dots, and the specific preparation steps and parameters are as follows:

[0114] Preparation of cesium oleate precursor:

[0115] Dissolve 0.8 g of Cs2CO3 powder in 3 mL of oleic acid and 30 mL of octadecene. Place the mixture in a 100 mL three-necked flask and heat to 120 degrees under vacuum for 60 min until the powder is completely dissolved.

[0116] Synthesis of CsPbCl3:Yb perovskite quantum dots

[0117] 0.3mmol of PbCl2 and 0.15mmol of YbCl3·6H2O were dissolved in 10mL of octadecene, 1.3mL of oleic acid, 0.625mL of oleylamine, and 0.5mL of methanol, where methanol was used as a cosolvent. The mixture was placed in a 100mL three-necked flask and placed on a magnetic stirring heating mantle. After stirring and dissolving at 30 degrees for 10 minutes, it was heated to 120 degrees under vacuum and kept for 30 minutes to completely dissolve the drug. After the drug was completely dissolved, the temperature was raised to 250 degrees under a nitrogen environment, and 0.5mL of cesium oleate precursor solution and 0.625mL of octylamine were quickly injected to react for 10s, and then cooled with ice water. The obtained product was centrifuged at 5000rpm for 5min, the supernatant was discarded, the precipitate was redispersed in 10mL of toluene solution and shaken well, and the upper liquid was obtained by centrifugation at 8000rpm for 5min, the supernatant was discarded, the precipitate was redispersed in 5mL of n-hexane solution and shaken well, and then allowed to stand for use. The obtained near-infrared luminescence spectrum of CsPbCl3:Yb perovskite quantum dots is as follows Figure 5 shown.

[0118] Test Case

[0119] The luminescence performance of the ytterbium-doped perovskite quantum dots obtained in each embodiment and comparative example was tested, and the specific testing method was as follows:

[0120] The fluorescence quantum dot detection system is used for testing, and the fluorescence spectrum is directly output; the photoluminescence quantum efficiency (PLQY) test system provided in the fluorescence quantum dot detection system is used to obtain the near-infrared and visible light luminescence quantum efficiency diagrams of each quantum dot.

[0121] from Figures 1 to 4 It can be seen that when long-chain ligands or short-chain ligands are used alone, the overall near-infrared quantum efficiency (QY) of the sample is low, and some visible light is emitted. The appearance of visible light indicates that the sample has a low ability to convert excitation light into near-infrared light. However, when long-chain and short-chain amines (such as C6~C 12After the combination of alkylamine and oleylamine, the near-infrared QY of quantum dots is greatly improved, and the sample has almost no visible light emission, indicating that it has a strong ability to convert excitation light into near-infrared light.

[0122] Figure 5 This is the fluorescence spectrum of the quantum dots obtained in Comparative Example 3. It can be seen from the figure that the overall near-infrared QY of the sample is very low (the proportion of visible light is high, and the proportion of infrared light is naturally low), and the visible light luminescence is too strong. This is because the amount of long-chain ligands in the early stage is insufficient, and the final addition of short-chain amine ligands will result in too short a reaction time. The ligands cannot effectively complex with the samples, which directly affects the luminescence performance of the quantum dots.

[0123] Figure 6 The near-infrared and visible light photoluminescence quantum efficiency (PLQY) diagrams of the quantum dots provided for Examples 1-2 and Comparative Examples 1-2 show that the near-infrared photoluminescence quantum efficiency of Examples 1-2 is much higher than that of Comparative Examples 1 and 2, and the visible light photoluminescence quantum efficiency of Examples 1-2 and Comparative Example 2 is almost 0, but the near-infrared photoluminescence quantum efficiency of Comparative Example 2 is also very low.

[0124] The fluorescence spectra, near-infrared and visible light photoluminescence quantum efficiency diagrams of the quantum dots obtained in Examples 3 to 9 are similar to those in Examples 1 to 2 and are not shown one by one.

[0125] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention.

Claims

1. A method for preparing a near-infrared luminescent ytterbium-doped quantum dot material, characterized in that: The method comprises the following steps: injecting a cesium-containing precursor solution into a lead- and ytterbium-containing precursor solution for reaction; The lead and ytterbium-containing precursor solution includes short-chain amines and long-chain amines, wherein the total number of carbon chain atoms M of the short-chain amines satisfies 6≤M≤12, and the total number of carbon chain atoms N≥16 of the long-chain amines.

2. The method for preparing the near-infrared luminescent ytterbium-doped quantum dot material according to claim 1, characterized in that: The volume ratio of the short-chain amine to the long-chain amine is (0.66-1.5):1; And / or, the short-chain amine includes C6~C 12 and / or, the long-chain amine comprises oleylamine.

3. The method for preparing the near-infrared luminescent ytterbium-doped quantum dot material according to claim 1 or 2, characterized in that: The lead and ytterbium-containing precursor solution also includes a supplemental halogen source; Optionally, the supplementary halogen source includes at least one of oleylamine chloride, oleylamine bromide, octylamine chloride, octylamine bromide, trimethylbromosilane, and trimethylchlorosilane.

4. The method for preparing the near-infrared luminescent ytterbium-doped quantum dot material according to claim 1 or 2, characterized in that: The lead and ytterbium-containing precursor solution also includes a co-solvent; Optionally, the co-solvent includes at least one of methanol, ethanol and propanol.

5. The method for preparing the near-infrared luminescent ytterbium-doped quantum dot material according to claim 1 or 2, characterized in that: The reaction temperature is 240-270°C and the reaction time is greater than 5s; Optionally, the reaction time is 5 to 100 s.

6. The method for preparing the near-infrared luminescent ytterbium-doped quantum dot material according to claim 1 or 2, characterized in that: The steps of preparing the cesium-containing precursor solution include: mixing and dissolving a cesium source, oleic acid and octadecene; Optionally, the cesium source includes at least one of cesium carbonate and cesium acetate; And / or, in the cesium-containing precursor solution, the concentration of the cesium source is 0.1 to 0.3 mol / L, calculated as cesium ions.

7. The method for preparing the near-infrared luminescent ytterbium-doped quantum dot material according to any one of claims 1 to 6, characterized in that: The preparation method of the lead and ytterbium-containing precursor solution comprises: mixing and dissolving a lead source, an ytterbium source, a halogen source and / or a supplementary halogen source, a short-chain amine, a long-chain amine, oleic acid and octadecene; Optionally, the lead source includes at least one of lead chloride, lead bromide, lead acetate, lead oxide, lead stearate, and lead oleate; Optionally, the ytterbium source includes at least one of ytterbium chloride, ytterbium bromide, ytterbium acetate, and ytterbium oleate; Optionally, the halogen source includes at least one of oleylamine chloride, oleylamine bromide, octylamine chloride, octylamine bromide, trimethylbromosilane, and trimethylchlorosilane.

8. The method for preparing the near-infrared luminescent ytterbium-doped quantum dot material according to claim 7, characterized in that: In the reaction system, the concentration of the lead source is 0.01-0.05 mol / L; and / or, the concentration of the ytterbium source is 0.5 to 4 times the concentration of the lead source; and / or, the concentration of total halogen ions is 3.5 to 14 times the concentration of the lead source; and / or, the concentration of the cesium source is 0.3 to 1 times the concentration of the lead source, calculated as cesium ions; and / or, a bromine / chloride ion ratio of 0 to 0.2; And / or, the concentration of the short-chain amine is 10 to 50 times the concentration of the lead source.

9. A near-infrared luminescent ytterbium-doped quantum dot material prepared by the preparation method according to any one of claims 1 to 7.

10. An application of the near-infrared luminescent ytterbium-doped quantum dot material according to claim 9 in the fields of solar cells, light-emitting diodes, detectors, lasers, and display panels.

Images