Efficient perovskite quantum dot with quantum cutting effect and preparation method thereof

Abstract

The invention discloses an efficient perovskite quantum dot with a quantum cutting effect and a preparation method thereof. The preparation method comprises the following steps: mixing cesium carbonate, oleic acid and 1-octadecene for reaction to obtain a solution A; mixing and reacting lead chloride, ytterbium chloride, oleic acid, oleylamine and 1-octadecene to obtain a solution B; injecting the solution A into the solution B, reacting, cooling, centrifugally precipitating, and extracting to obtain perovskite quantum dot supernate; mixing metal chloride and absolute ethyl alcohol, dropwise adding the mixture into the supernate, and performing ultrasonic treatment to obtain the efficient perovskite quantum dots with the quantum cutting effect. The method is simple and convenient to operate, does not need harsh reaction conditions, and can remarkably improve the preparation efficiency and reduce the preparation cost; according to the perovskite quantum dot, through the synergistic effect of metal ion doping and the quantum cutting effect, effective passivation of a defect state is achieved on the premise that quantum cutting near-infrared light emission is completely kept, non-radiative recombination is reduced, the overall fluorescence quantum yield is increased, and the comprehensive fluorescence performance is excellent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of perovskite quantum dot preparation, and particularly to a high-efficiency perovskite quantum dot with quantum clipping effect and a preparation method thereof. BACKGROUND

[0002] Solar energy, as a new energy, has been widely valued due to its high efficiency and cleanness. At present, the main ways for solar energy utilization are light-heat conversion and photoelectric conversion. Among them, photoelectric conversion is to convert solar energy into electrical energy through photovoltaic effect, and the basic device is solar cell. The technology of realizing photoelectric conversion by using photovoltaic effect is collectively referred to as photovoltaic technology. In the development of various solar cell photovoltaic technologies, the efficiency limit has always been a bottleneck restricting its development. Whether inorganic or organic solar cells will have certain energy loss. Taking monocrystalline silicon solar cell as an example, its limit efficiency is only 29%. The main reason is that the absorption band gap of the solar cell does not match the solar spectrum, especially the high-energy spectrum of ultraviolet and blue-violet light bands cannot be fully utilized, thereby affecting the limit efficiency of the cell.

[0003] In order to fully utilize the spectrum of ultraviolet and blue-violet light bands and solve the problem of mismatch between solar cell and solar spectrum, spectrum conversion technology can be used to make the absorption spectrum of the cell more matched with the solar spectrum. At present, perovskite quantum dots, as an effective spectrum conversion material, have been applied in the spectrum conversion layer of solar cells.

[0004] All-inorganic perovskite quantum dots (CsPbX3, X = Cl, Br, I) have shown great potential in optoelectronic devices (LED, solar cell, near-infrared detector) due to their excellent optoelectronic properties (such as high fluorescence quantum yield, narrow emission peak, spectral tunability, etc.). However, the application of existing perovskite quantum dots in the spectrum conversion layer still faces some challenges, especially in improving the emission efficiency. For example, the emission efficiency of perovskite quantum dots in the blue-violet light range (such as CsPbCl3) is still insufficient, which seriously limits their performance in practical applications. And the quantum dots that realize high-efficiency dual-band (blue-violet light + near-infrared) emission in the existing technology also face challenges. Therefore, how to improve the emission efficiency and realize high-efficiency dual-band emission has become a key problem in the research of perovskite quantum dots.

[0005] At present, some studies have tried to introduce quantum clipping effect by doping a single rare earth ion (such as Yb 3+ ), but due to the low compatibility of perovskite lattice with rare earth ions, the doping concentration is limited, the energy transfer efficiency is low, the near-infrared emission intensity is weak, and the blue-violet light emission is significantly suppressed due to energy loss. In addition, Hu et al. achieved doping by injecting metal precursors, but the reaction conditions are harsh and easy to cause lattice defects, resulting in low emission efficiency. SUMMARY

[0006] The present application provides a kind of high-efficiency perovskite quantum dots with quantum tailoring effect and preparation method thereof, metal chloride anhydrous ethanol solution is dropped to perovskite quantum dot supernatant under room temperature condition, and metal ion doping can be realized by ultrasonic treatment, and the doping method is simple, and the condition is mild, without harsh condition, the blue-violet light emission intensity and near-infrared light emission intensity of the obtained high-efficiency perovskite quantum dots with quantum tailoring effect are stronger, and the fluorescence quantum yield is high, and the luminous efficiency is good.

[0007] To solve the above technical problems, the first aspect of the present application provides a preparation method of high-efficiency perovskite quantum dots with quantum tailoring effect, comprising the following steps:

[0008] S1, cesium carbonate, oleic acid and 1-octadecene are mixed to obtain a first mixed solution, and after degassing and reaction under vacuum environment and T1 temperature to generate cesium oleate, protective gas is introduced and heated to T2 temperature until cesium carbonate is completely dissolved to obtain A solution;

[0009] S2, lead chloride, ytterbium chloride, oleic acid, oleylamine and 1-octadecene are mixed to obtain a second mixed solution, and after degassing under vacuum environment and T3 temperature, protective gas is introduced and heated to T4 temperature to obtain B solution;

[0010] S3, after A solution is injected into B solution for reaction, the temperature is lowered to T5, and the perovskite quantum dot supernatant is obtained by centrifugal precipitation and extraction;

[0011] S4, at room temperature, metal chloride and anhydrous ethanol are mixed to obtain a third mixed solution, which is added to the supernatant, and ultrasonic treatment is performed, so that the metal ions and chloride ions in the metal chloride fill the vacancy defects of the perovskite quantum dots, and the high-efficiency perovskite quantum dots with quantum tailoring effect are obtained.

[0012] In the present application, anhydrous ethanol solution of metal chloride is controllably added to perovskite quantum dot supernatant, and metal ions and chloride ions are filled into vacancy defects of perovskite quantum dots by ultrasonic treatment, so that high-efficiency perovskite quantum dots with quantum tailoring effect are obtained, which are simple and convenient to operate, do not need to rely on expensive equipment and harsh reaction conditions, can significantly improve the preparation efficiency and reduce the preparation cost, and have good comprehensive fluorescence performance.

[0013] Further, in S1, the volume ratio of oleic acid and 1-octadecene is (1-2):(10-14); the concentration of cesium carbonate in the first mixed solution is 20-27 mg / mL.

[0014] Further, in S2, the volume ratio of oleic acid, oleylamine and 1-octadecene is (1-2):(1-2):(8-12); the concentration of lead chloride in the second mixed solution is 5.6-6.9 mg / mL; the concentration of ytterbium chloride in the second mixed solution is 7.7-10.0 mg / mL.

[0015] Further, the T1 temperature is 110-130 DEG C, the T2 temperature is 140-160 DEG C, the T3 temperature is 110-130 DEG C, the T4 temperature is 220-260 DEG C, and the T5 temperature is 30-40 DEG C.

[0016] Further, in S1 and S2, the T1 temperature and the T3 temperature are maintained respectively until the solution stops bubbling and then the temperature is raised.

[0017] Further, in S3, the volume ratio of A solution to B solution is 1:(10-15).

[0018] Further, in S3, the reaction time is 25-35 s.

[0019] Further, in S4, the metal chloride is one or more of CdCl2, NiCl2, MgCl2 and CaCl2.

[0020] Further, in S4, the ratio of the metal chloride to anhydrous ethanol is (0.1-0.15) mmol:(2-4) mL.

[0021] Further, in S4, the volume ratio of the third mixed solution to the supernatant is 1:(25-35).

[0022] The second aspect of the present application provides the high-efficiency perovskite quantum dots with quantum confinement effect prepared by the preparation method of the first aspect.

[0023] The present application has the following advantages:

[0024] The present application can fill metal ions and chloride ions into the vacancy defects of perovskite quantum dots by controllably adding anhydrous ethanol solution of metal chloride to the supernatant of perovskite quantum dots and ultrasonic treatment, so that high-efficiency perovskite quantum dots with quantum confinement effect are obtained, which is simple and convenient to operate, does not need to rely on expensive equipment and harsh reaction conditions, can significantly improve the preparation efficiency and reduce the preparation cost.

[0025] The perovskite quantum dots prepared by the preparation method have the synergistic effect of metal ion doping and quantum confinement effect, on the premise of completely maintaining quantum confinement near-infrared luminescence, the type of metal ion is optimized to realize effective passivation of defect states, reduce non-radiative recombination, improve blue light fluorescence quantum yield, and improve overall fluorescence quantum yield, and the comprehensive fluorescence performance is good. DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be clearly and completely described below in combination with specific embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0027] The present embodiment of the present application relates to a preparation method of high-efficiency perovskite quantum dots with quantum confinement effect, comprising the following steps:

[0028] S1, mixing cesium carbonate, oleic acid and 1-octadecene to obtain a first mixed solution, degassing under vacuum environment and T1 temperature, and then reacting to generate cesium oleate, then introducing protective gas and heating to T2 temperature until the cesium carbonate is completely dissolved to obtain A solution;

[0029] S2, mixing lead chloride, ytterbium chloride, oleic acid, oleylamine and 1-octadecene to obtain a second mixed solution, degassing under vacuum environment and T3 temperature, then introducing protective gas and heating to T4 temperature to obtain B solution;

[0030] S3, after injecting A solution into B solution for reaction, cooling to T5 temperature, centrifugal precipitation, and then extracting to obtain perovskite quantum dot supernatant;

[0031] S4, at room temperature, mixing metal chloride and anhydrous ethanol to obtain a third mixed solution, adding the third mixed solution dropwise into the supernatant, and then ultrasonic treatment, so that the metal ions and chloride ions in the metal chloride fill the vacancy defects of the perovskite quantum dots, to obtain high-efficiency perovskite quantum dots with quantum confinement effect.

[0032] In this embodiment, the anhydrous ethanol solution of metal chloride is controllably added to the perovskite quantum dot supernatant, and the metal ions and chloride ions are filled into the vacancy defects of the perovskite quantum dots through ultrasonic treatment, to obtain high-efficiency perovskite quantum dots with quantum confinement effect. The operation is simple and convenient, does not need to rely on special equipment, and does not need harsh reaction conditions, so that the preparation efficiency can be significantly improved and the preparation cost can be reduced. The perovskite quantum dots prepared by the preparation method have the synergistic effect of metal ion doping and quantum confinement effect, on the premise of completely maintaining quantum confinement near-infrared luminescence, the type of metal ion is optimized to realize effective passivation of defect states, reduce non-radiative recombination, improve blue light fluorescence quantum yield, and improve overall fluorescence quantum yield, and the comprehensive fluorescence performance is good.

[0033] As a preferred embodiment, in S1, the volume ratio of oleic acid and 1-octadecene is (1-2):(10-14); the concentration of cesium carbonate in the first mixed solution is 20-27 mg / mL; in S2, the volume ratio of oleic acid, oleylamine and 1-octadecene is (1-2):(1-2):(8-12); the concentration of lead chloride in the second mixed solution is 5.6-6.9 mg / mL; the concentration of ytterbium chloride in the second mixed solution is 7.7-10.0 mg / mL; in S1 and S2, the temperature is maintained at T1 and T3 respectively until the solution stops bubbling and then the temperature is increased.

[0034] As a preferred embodiment, the T1 temperature is 110-130℃, the T2 temperature is 140-160℃, the T3 temperature is 110-130℃, the T4 temperature is 220-260℃, and the T5 temperature is 30-40℃.

[0035] As a preferred embodiment, in S3, the volume ratio of A solution to B solution is 1:(10-15); the reaction time is 25-35 s.

[0036] As a preferred embodiment, in S4, the metal chloride is one or more of CdCl2, NiCl2, MgCl2, CaCl2; the ratio of the metal chloride to anhydrous ethanol is (0.1-0.15) mmol:(2-4) mL; the volume ratio of the third mixed solution to the supernatant is 1:(25-35).

[0037] Another embodiment provides a high-efficiency perovskite quantum dot with quantum confinement effect prepared by the preparation method described in the above embodiments, wherein the perovskite quantum dot is doped with metal ions.

[0038] Embodiment 1

[0039] The present embodiment relates to a preparation method of a high-efficiency perovskite quantum dot with quantum confinement effect, comprising the following steps:

[0040] (1) In a vacuum environment, 0.4 g of cesium carbonate (Cs2CO3), 1.25 mL of oleic acid (OA) and 15 mL of 1-octadecene (ODE) are mixed, and degassing is carried out under continuous stirring at 120℃ until bubbling stops, nitrogen is introduced, and heating is continued to 150℃, and stirring is continued until all Cs2CO3 is dissolved to obtain a clear A solution;

[0041] (2) 0.08 g of lead chloride (PbCl2), 0.12 g of ytterbium chloride (YbCl3), 1 mL of oleic acid, 1 mL of oleylamine (OAM), 10 mL of 1-octadecene were mixed, stirred under vacuum and heated to 120°C for 60 min until the solution stopped bubbling, and then nitrogen was introduced and heated to 240°C to obtain solution B;

[0042] (3) 1 mL of solution A was quickly injected into 12 mL of solution B, and after 30 s of reaction, the solution was quickly cooled to 40°C, and then centrifuged at 12000 r / min for 6 min. The precipitate was added with cyclohexane and centrifuged at 8000 r / min for 5 min, and finally the supernatant was taken;

[0043] (4) 0.13 mmol of CdCl2 was mixed with 3 mL of anhydrous ethanol, and ultrasonic treatment was performed for 5 min until the solution became clear. The obtained CdCl2 stock solution was added dropwise to 100 μL of the 1 mL supernatant, and ultrasonic mixing was performed for 3 min to obtain the Cd-doped perovskite quantum dots. 2+ Perovskite quantum dots with quantum confinement effect

[0044] Example 2

[0045] The difference between this example and Example 1 is that CdCl2 in step (4) is replaced by NiCl2, and other steps and parameters remain unchanged.

[0046] Example 3

[0047] The difference between this example and Example 1 is that CdCl2 in step (4) is replaced by MgCl2, and other steps and parameters remain unchanged.

[0048] Example 4

[0049] The difference between this example and Example 1 is that CdCl2 in step (4) is replaced by CaCl2, and other steps and parameters remain unchanged.

[0050] Comparative Example 1

[0051] The difference between this example and Example 1 is that step (4) is omitted, and other steps and parameters remain unchanged.

[0052] Test Example

[0053] The fluorescence quantum yields of the perovskite quantum dots obtained in Examples 1-4 and Comparative Example 1 were tested, and the results are shown in Table 1.

[0054] Table 1

[0055] Group Composition Blue photoluminescence quantum yield Near-infrared photoluminescence quantum yield Example 1 CsPbCl3:Yb,Cd 17.2％ 114.3％ Example 2 CsPbCl3:Yb, Ni 12.4％ 112.2％ Example 3 CsPbCl3:Yb, Mg 12.4％ 113.5％ Example 4 CsPbCl3:Yb,Ca 12.8％ 113.4％ Comparative Example 1 CsPbCl3:Yb 8.7％ 113.1％

[0056] As can be seen from Table 1, compared with the single rare earth ion (Yb 3+ ) doped perovskite quantum dots obtained in Comparative Example 1, the blue fluorescence quantum yield of the metal ion doped perovskite quantum dots obtained in Examples 1-4 is significantly improved, and the near-infrared fluorescence quantum yield does not decrease significantly and is basically maintained, the overall fluorescence quantum yield is improved, and the comprehensive fluorescence performance is good. Therefore, the method of the present application adopts a simple and convenient metal chloride stock solution dropwise addition method, and through the synergistic effect of metal ion doping and quantum cutting, not only the near-infrared luminescence of quantum cutting effect can be completely maintained, but also the overall fluorescence quantum yield can be improved.

[0057] In summary, by controllably adding anhydrous ethanol solution of metal chloride to supernatant of perovskite quantum dots, and then ultrasonic treatment, metal ions and chloride ions can be filled into the vacancy defects of perovskite quantum dots, and high-efficiency perovskite quantum dots with quantum cutting effect can be obtained. The operation is simple and convenient, does not need to rely on expensive equipment, and does not need harsh reaction conditions, which can significantly improve the preparation efficiency and reduce the preparation cost. The obtained perovskite quantum dots, through the synergistic effect of metal ion doping and quantum cutting effect, completely maintain the near-infrared luminescence of quantum cutting, optimize the type of metal ions to realize effective passivation of defect states, reduce non-radiative recombination, improve blue fluorescence quantum yield, improve overall fluorescence quantum yield, and have good comprehensive fluorescence performance.

[0058] The above detailed description of the present application is made in combination with specific embodiments and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that the technical solutions and embodiments of the present application can be variously replaced, modified or improved without departing from the spirit and scope of the present application, and these all fall within the scope of the present application. The protection scope of the present application is subject to the appended claims.

Claims

1. A method for preparing high-efficiency perovskite quantum dots with quantum confinement effect, characterized in that, The method comprises the following steps: S1, mixing cesium carbonate, oleic acid and 1-octadecene to obtain a first mixed solution, degassing under vacuum and at a T1 temperature, and then reacting to generate cesium oleate, then introducing a protective gas and heating to a T2 temperature until the cesium carbonate is completely dissolved to obtain an A solution; S2, mixing lead chloride, ytterbium chloride, oleic acid, oleylamine and 1-octadecene to obtain a second mixed solution, degassing under vacuum and at a T3 temperature, then introducing a protective gas and heating to a T4 temperature to obtain a B solution; S3, after injecting the A solution into the B solution for reaction, cooling to a T5 temperature, centrifugal precipitation, extraction to obtain a perovskite quantum dot supernatant; S4, mixing a metal chloride and anhydrous ethanol at room temperature to obtain a third mixed solution, dropping into the supernatant, and ultrasonic treatment, so that metal ions and chloride ions in the metal chloride fill the vacancy defects of the perovskite quantum dots to obtain high-efficiency perovskite quantum dots with quantum confinement effect.

2. The method for preparing high-efficiency perovskite quantum dots with quantum cutting effect as described in claim 1, characterized in that, In S1, the volume ratio of the oleic acid and 1-octadecene is (1-2):(10-14); and the concentration of the cesium carbonate in the first mixed solution is 20-27 mg / mL.

3. The method for preparing high-efficiency perovskite quantum dots with quantum cutting effect as described in claim 1, characterized in that, In S2, the volume ratio of the oleic acid, oleylamine and 1-octadecene is (1-2):(1-2):(8-12); the concentration of the lead chloride in the second mixed solution is 5.6-6.9 mg / mL; and the concentration of the ytterbium chloride in the second mixed solution is 7.7-10.0 mg / mL.

4. The method for preparing high-efficiency perovskite quantum dots with quantum cutting effect as described in claim 1, characterized in that, The T1 temperature is 110-130 DEG C, the T2 temperature is 140-160 DEG C, the T3 temperature is 110-130 DEG C, the T4 temperature is 220-260 DEG C, and the T5 temperature is 30-40 DEG C.

5. The method for preparing high-efficiency perovskite quantum dots with quantum cutting effect as described in claim 1, characterized in that, In S1 and S2, the T1 temperature and the T3 temperature are respectively maintained until the solution stops bubbling, and then the temperature is increased.

6. The method for preparing high-efficiency perovskite quantum dots with quantum cutting effect as described in claim 1, characterized in that, In S3, the volume ratio of the A solution to the B solution is 1:(10-15).

7. The method for preparing high-efficiency perovskite quantum dots with quantum cutting effect as described in claim 1, characterized in that, In S4, the metal chloride is one or more of CdCl2, NiCl2, MgCl2 and CaCl2.

8. The method for preparing high-efficiency perovskite quantum dots with quantum cutting effect as described in claim 1, characterized in that, In S4, the ratio of the metal chloride to the anhydrous ethanol is (0.1-0.15) mmol:(2-4) mL.

9. The method for preparing high-efficiency perovskite quantum dots with quantum cutting effect as described in claim 1, characterized in that, In S4, the volume ratio of the third mixed solution to the supernatant is 1:(25-35).

10. High-efficiency perovskite quantum dots with quantum confinement effect obtained by the preparation method of any one of claims 1-9.