CN111676010A - Preparation method of perovskite quantum dots/Eu-MOF composite light-emitting material - Google Patents

Abstract

The invention discloses a preparation method of a perovskite quantum dot/Eu-MOF composite light-emitting material, comprising the following steps: S1. adding europium nitrate hexahydrate and biphenyltetracarboxylic acid into a mixed solution of DMF and water for heating and cooling, Remove residual DMF, and vacuum dry to obtain Eu-MOF crystals; S2. Mix the dried Eu-MOF crystals with the DMF solution of PbBr ₂ to obtain a precursor solution of PbBr ₂ @Eu-MOF; S3. Add CsBr and stir until it becomes clear Then add oleyl amine oleate; then transfer to toluene to prepare perovskite quantum dots/Eu-MOF composite luminescent material; S4. The above materials are centrifugally dispersed in n-hexane solution, stirred and filtered out of the precipitation and other steps to prepare The high-purity perovskite quantum dots/Eu-MOF composite light-emitting material solves the problem of poor stability of perovskite quantum dots and the lack of the red light region of the current white light LEDs.

Description

Preparation method of perovskite quantum dots/Eu-MOF composite light-emitting material

technical field

The invention relates to the field of composite light-emitting materials, in particular to a preparation method of a perovskite quantum dot/Eu-MOF composite light-emitting material.

Background technique

All-inorganic perovskite quantum dots CsPbX ₃ (X=Cl, Br, I) have the advantages of high quantum yield, tunable luminescence, narrow emission spectrum and wide color gamut, etc., showing great potential in optoelectronic devices . However, due to their ionic properties, perovskite quantum dots suffer from poor chemical stability under ambient conditions and are very sensitive to humidity, light, and temperature. In addition, the high ionization of the internal bond makes it highly susceptible to ion exchange reactions. How to solve the stability problem of perovskite quantum dots has become an urgent problem to be solved.

MOFs are characterized by porosity, high specific surface area, unsaturated metal sites, and structural diversity, which endow them with some special physicochemical properties. In recent years, it has received extensive attention from researchers and has shown application prospects in many fields such as gas storage and separation, molecular recognition, opto-electromagnetic materials, and drug delivery. MOFs can be used as host materials to accept a variety of guest materials to realize the assembly of novel functional materials. As mentioned earlier, perovskite quantum dots have also been the focus of research in recent years. Therefore, the combination of the two is bound to realize the regulation and synergistic improvement of performance, and various new quantum dots@MOFs composite materials have emerged as the times require, and their application fields have also continued to expand.

At present, the white light LED mainly adopts the device structure of blue light chip + yellow phosphor that can be effectively excited by blue light, but this structure has the obvious disadvantage that it lacks the red light component, and the spectrum does not fully cover the visible light range. Color index is low. In order to solve the problem of lack of red light, there are a lot of studies to realize the combined luminescence of perovskite quantum dots and rare earth ions by doping with rare earth ions, but this method still inevitably has the problem of poor stability of perovskite quantum dots. , and the doping amount of rare earth ions is limited, so large dose doping cannot be achieved, and the luminescence of rare earth ions is much weaker than that of perovskite quantum dots.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a preparation method of perovskite quantum dots/Eu-MOF composite light-emitting material, use Eu-MOF to stabilize perovskite quantum dots, solve the problem of poor stability of perovskite quantum dots, and solve At present, the problem of missing red light region in white light LED exists.

In order to achieve the above object, the technical scheme of the present invention is achieved in this way:

The invention provides a preparation method of a perovskite quantum dot/Eu-MOF composite light-emitting material, comprising the following steps:

S1. Europium nitrate hexahydrate and biphenyltetracarboxylic acid are added in the mixed solution of DMF and water, and the mol ratio of described europium nitrate hexahydrate and biphenyltetracarboxylic acid is 1:(0.2-1);

Put the mixed solution into the reaction kettle and heat it to 100-150℃ for 10-48h; naturally cool to room temperature, purify the product by suction filtration, remove the residual DMF, and obtain Eu-MOF crystal after vacuum drying;

S2. After mixing and stirring the dried Eu-MOF crystal with the DMF solution of PbBr ₂ for a certain period of time, a precursor solution of PbBr ₂ @Eu-MOF is obtained;

S3. Add CsBr to the precursor solution of PbBr ₂ @Eu-MOF, stir until it becomes clear, then add oleylamine oleate; then transfer to toluene to prepare perovskite quantum dots/Eu-MOF composite luminescent material;

S4. Centrifugally disperse the perovskite quantum dots/Eu-MOF composite luminescent material preliminarily obtained in step S3 in a n-hexane solution, stir evenly, filter out the precipitate, remove the remaining perovskite quantum dots on the surface, vacuum dry, and prepare A high-purity perovskite quantum dot/Eu-MOF composite luminescent material was obtained.

Further, the molar ratio of europium nitrate hexahydrate and biphenyltetracarboxylic acid in the step S1 is 1:0.6.

Further, in the step S1, the volume ratio of DMF and water is 5:(0.5-2).

Further, in the step S1, the Eu-MOF crystal is obtained by vacuum drying at a temperature of 50-80° C. for 5-10 hours.

Further, in the step S2, the volume of the DMF solution is 5-20ml, and the stirring time of the Eu-MOF crystal and the DMF solution of PbBr ₂ is 6-24h.

Further, in the step S2, the molar ratio of CsBr to PbBr ₂ is 1:1.

Further, in the step S3, the volume ratio of the prepared mixed precursor solution of CsBr and PbBr ₂ @Eu-MOF to toluene is (0.1-2):10.

Further, the perovskite quantum dot/Eu-MOF composite light-emitting material prepared by the preparation method is used in LEDs.

Further, the perovskite quantum dots/Eu-MOF composite luminescent material is mixed with UV curing glue, drop-coated on the blue LED chip, and cured under UV light to obtain a white LED.

Using the above technical solution, the preparation method of the perovskite quantum dot/Eu-MOF composite light-emitting material provided by the present application has the following technical effects:

1) This application adopts the step of mixing MOF with PbBr ₂ first, which can make the MOF adsorb Pb ²⁺ ions, which is beneficial to the next step of composite material synthesis, so that the perovskite quantum dots and MOF are better combined, and Perovskite quantum dots have better dispersion in MOF, which improves the stability of perovskite quantum dots and effectively retains the excellent optical properties of perovskite quantum dots;

2) By adjusting the composition of perovskite quantum dots, the perovskite quantum dots CsPbX ₃ /Eu-MOF composite luminescent material covering the visible light range can be obtained;

3) Utilizing the green light-emitting properties of perovskite quantum dots and the red light-emitting properties of rare-earth MOFs, a composite light-emitting material capable of emitting green light and red light at the same time is synthesized. The composite light-emitting material solves the problem of perovskite quantum dots in LEDs. The application problems have improved the application of perovskite quantum dots in LEDs;

4) The raw materials in this application are simple, the reaction conditions are mild, and the operation is simple and efficient.

Description of drawings

In order to illustrate the specific embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the specific embodiments or the prior art. Obviously, the accompanying drawings in the following description The drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

FIG. 1 is a transmission electron microscope (TEM) image of the CsPbBr ₃ /Eu-MOF composite light-emitting material prepared in Example 1. FIG.

FIG. 2 is an emission spectrum diagram of the CsPbBr ₃ /Eu-MOF composite light-emitting material prepared in Example 1. FIG.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings.

The present application provides a preparation method of perovskite quantum dots/Eu-MOF composite light-emitting material, and the preparation method includes the following steps:

S1. adding europium nitrate hexahydrate and biphenyl tetracarboxylic acid to the aqueous solution of DMF (N,N-dimethylformamide), the mol ratio of europium nitrate hexahydrate and biphenyl tetracarboxylic acid is 1: (0.2-1 );

The above mixed solution was put into the reactor and heated to 100-150°C for 10-48h; naturally cooled to room temperature, the product was purified by suction filtration, the residual DMF (N,N-dimethylformamide) was removed, and the vacuum After drying, Eu-MOF crystals were obtained;

In the above scheme, the rigid and highly symmetrical biphenyltetracarboxylic acid is used to prepare Eu-MOF crystals, which has a more excellent energy transfer effect, thereby obtaining MOF materials with excellent fluorescence properties;

S2. After mixing and stirring the dried Eu-MOF crystal with the DMF solution of PbBr ₂ for a certain period of time, a precursor solution of PbBr ₂ @Eu-MOF is obtained;

S3. Add CsBr to the precursor solution of PbBr ₂ @Eu-MOF, stir until it becomes clear, then add oleylamine oleate; then transfer to toluene to prepare perovskite quantum dots/Eu-MOF composite luminescent material;

S4. Centrifugally disperse the perovskite quantum dots/Eu-MOF composite luminescent material preliminarily prepared in the above step S3 in a n-hexane solution, stir evenly, filter out the precipitate, remove the residual perovskite quantum dots on the surface, and vacuum dry , a high-purity perovskite quantum dot/Eu-MOF composite luminescent material was prepared.

In a preferred embodiment, the molar ratio of europium nitrate hexahydrate and biphenyltetracarboxylic acid in the step S1 is 1:0.6.

In a preferred embodiment, in the step S1, the volume ratio of DMF and water is 5:(0.5-2), and in practical application, the volume ratio of DMF and water can be 5:0.5, 5:1, or 5: 2 equal proportions.

In a preferred embodiment, in the step S1, the Eu-MOF crystals are prepared by vacuum drying at a temperature of 50-80 °C for 5-10 hours. Alternatively, the Eu-MOF crystals are prepared by vacuum drying at a temperature of 60 °C for 8 hours. have to.

In a preferred embodiment, in the step S2, the volume of the DMF solution is 5-20ml, and the stirring time of the Eu-MOF crystal and the DMF solution of PbBr ₂ is 6-24h.

In a preferred embodiment, in the step S2, the molar ratio of CsBr to PbBr ₂ is 1:1.

In a preferred embodiment, in the step S3, the volume ratio of the prepared mixed precursor solution of CsBr and PbBr ₂ @Eu-MOF to toluene is (0.1-2): 10, for example, when applied, CsBr and PbBr ₂ The volume ratio of the mixed precursor solution of @Eu-MOF to toluene can be 0.1:10, 1:10, or 2:10.

The preparation method of the above-mentioned perovskite quantum dots/Eu-MOF composite luminescent material provided in this application:

The solvothermal method is used to synthesize at room temperature, and can be prepared at room temperature without any inert atmosphere protection, which has the advantage of a simple preparation method;

In the process of compounding perovskite quantum dots and MOF, the present application adopts the step of mixing MOF with PbBr ₂ first, which can make MOF adsorb Pb ²⁺ ions, which is beneficial to the synthesis of composite materials in the next step. Better combination of perovskite quantum dots and MOF, and better dispersion of perovskite quantum dots in MOF;

In addition, using the green light-emitting properties of perovskite quantum dots and the red light-emitting properties of rare-earth MOFs, a composite light-emitting material that can emit green and red light at the same time is synthesized, and the rare-earth MOF plays the role of protecting the perovskite quantum dots. .

The preparation method of the present application will be described below with reference to specific examples.

Example 1

Weigh 1.784 g (4 mmol) of Eu(NO ₃ ) ₃ .6H ₂ O, 0.6605 g (2 mmol) of biphenyltetracarboxylic acid, add 7.5 ml of N,N-dimethylformamide (DMF) and 2.5ml of H ₂ O solution;

Then the above mixed solution was placed in the lining of a Teflon autoclave with a volume of 50ml, and heated at 120°C for 48 hours; after cooling, the obtained powder was filtered out and washed with DMF, and then washed with chloroform solution , to remove residual DMF;

The obtained product was vacuum dried at 80°C for 2 hours to obtain Eu-MOF crystals.

Mix and stir 0.4 g of the dried Eu-MOF crystal and 0.1468 g of PbBr ₂ in 10 ml of DMF solution for a period of time to obtain a precursor solution of PbBr ₂ @Eu-MOF;

Add 0.085g of CsBr solution to the precursor solution of PbBr ₂ @Eu-MOF, stir until it becomes clear, then add 1ml of oleic acid and 0.5ml of oleylamine;

Transfer 1 ml of the prepared solution to 10 ml of toluene solution to initially obtain perovskite quantum dots/Eu-MOF composite light-emitting materials;

The preliminarily prepared perovskite quantum dot/Eu-MOF composite luminescent material was centrifuged and dispersed in n-hexane solution at 8000-10000 r/min, and then the precipitate was filtered out by centrifugation and vacuum dried to obtain high-purity perovskite. Ore quantum dot/Eu-MOF composite luminescent material.

Example 2

Weigh 1.784 g (4 mmol) of Eu(NO ₃ ) ₃ .6H ₂ O, 0.6605 g (2 mmol) of biphenyltetracarboxylic acid, add 7.5 ml of N,N-dimethylformamide (DMF) and 2.5ml of H ₂ O solution;

Then the above-mentioned mixed solution was placed in a Teflon autoclave liner with a volume of 50 ml, and heated in a temperature environment of 100 ° C for 48 hours; after cooling, the obtained powder was filtered out and washed with DMF, and then washed with chloroform solution , to remove residual DMF;

The obtained product was vacuum dried at 80°C for 2 hours to obtain Eu-MOF crystals.

Mix and stir 0.4 g of the dried Eu-MOF crystal and 0.1468 g of PbBr ₂ in 10 ml of DMF solution for a period of time to obtain a precursor solution of PbBr ₂ @Eu-MOF;

Add 0.085g of CsBr solution to the precursor solution of PbBr ₂ @Eu-MOF, stir until it becomes clear, then add 1ml of oleic acid and 0.5ml of oleylamine;

Transfer 1 ml of the prepared solution to 10 ml of toluene solution to initially obtain perovskite quantum dots/Eu-MOF composite light-emitting materials;

The preliminarily prepared perovskite quantum dot/Eu-MOF composite luminescent material was centrifuged and dispersed in n-hexane solution at 8000-10000 r/min, and then the precipitate was filtered out by centrifugation and vacuum dried to obtain high-purity perovskite. Ore quantum dot/Eu-MOF composite luminescent material.

Example 3

Weigh 1.784 g (4 mmol) of Eu(NO ₃ ) ₃ .6H ₂ O, 0.6605 g (2 mmol) of biphenyltetracarboxylic acid, add 7.5 ml of N,N-dimethylformamide (DMF) and 2.5ml of H ₂ O solution;

Then the above mixed solution was placed in the lining of a Teflon autoclave with a volume of 50ml, and heated at 120°C for 48 hours; after cooling, the obtained powder was filtered out and washed with DMF, and then washed with chloroform solution , to remove residual DMF;

The obtained product was vacuum dried at 80°C for 2 hours to obtain Eu-MOF crystals.

Mix 0.4 g of the dried Eu-MOF crystal with 0.28 g of PbBr ₂ in 10 ml of DMF solution and stir for a period of time to obtain a precursor solution of PbBr ₂ @Eu-MOF;

Add 0.16g of CsBr solution to the precursor solution of PbBr ₂ @Eu-MOF, stir until it becomes clear, then add 1ml of oleic acid and 0.5ml of oleylamine;

Transfer 1 ml of the prepared solution to 10 ml of toluene solution to initially obtain perovskite quantum dots/Eu-MOF composite light-emitting materials;

The preliminarily prepared perovskite quantum dot/Eu-MOF composite luminescent material was centrifuged and dispersed in n-hexane solution at 8000-10000 r/min, and then the precipitate was filtered out by centrifugation and vacuum dried to obtain high-purity perovskite. Ore quantum dot/Eu-MOF composite luminescent material.

As shown in FIG. 1 , it is a transmission electron microscope (TEM) image of the CsPbBr ₃ /Eu-MOF composite light-emitting material prepared in Example 1. From Figure 1, it can be seen that _CsPbBr3 is successfully recombined with Eu-MOF.

The emission spectrum of the perovskite quantum dot CsPbBr ₃ /Eu-MOF composite light-emitting material prepared in Example 1 is shown in Figure 2. It can be seen from the figure that the CsPbBr ₃ /Eu-MOF composite light-emitting material achieves green A combination of light and red light glows.

In addition, the embodiments of the present application also provide a perovskite quantum dot/Eu-MOF composite light-emitting material, the composite light-emitting material is prepared by the above-mentioned preparation method, and the composite light-emitting material can be used in LEDs.

Preferably, in a specific application, the perovskite quantum dot/Eu-MOF composite luminescent material is mixed with an ultraviolet curing glue, and drop-coated on a blue LED chip, and after curing under ultraviolet light, a white light LED is obtained.

It should be noted that the current mainstream white light LEDs all use a combination of blue light and yellow light, so the red light part is lacking. The technical solution of the present application is to use CsPbBr ₃ perovskite quantum dots that emit green light and Rare earth EU-MOF is composed of composite light-emitting materials, and then combined with blue light chips to obtain white LEDs; and Eu-MOF can also play a protective role on perovskite quantum dots.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention. scope.

Claims (9)

1. a preparation method of perovskite quantum dot/Eu-MOF composite luminescent material, is characterized in that, comprises the steps: S1. Europium nitrate hexahydrate and biphenyltetracarboxylic acid are added in the mixed solution of DMF and water, and the mol ratio of described europium nitrate hexahydrate and biphenyltetracarboxylic acid is 1:(0.2-1); Put the mixed solution into the reaction kettle and heat it to 100-150℃ for 10-48h; naturally cool to room temperature, purify the product by suction filtration, remove the residual DMF, and obtain Eu-MOF crystal after vacuum drying; S2. After mixing and stirring the dried Eu-MOF crystal with the DMF solution of PbBr ₂ for a certain period of time, a precursor solution of PbBr ₂ @Eu-MOF is obtained; S3. Add CsBr to the precursor solution of PbBr ₂ @Eu-MOF, stir until it becomes clear, then add oleylamine oleate; then transfer to toluene to prepare perovskite quantum dots/Eu-MOF composite luminescent material; S4. Centrifugally disperse the perovskite quantum dots/Eu-MOF composite luminescent material preliminarily obtained in step S3 in a n-hexane solution, stir evenly, filter out the precipitate, remove the remaining perovskite quantum dots on the surface, vacuum dry, and prepare A high-purity perovskite quantum dot/Eu-MOF composite luminescent material was obtained. 2. preparation method as claimed in claim 1 is characterized in that, the mol ratio of europium nitrate hexahydrate and biphenyltetracarboxylic acid in step S1 is 1:0.6. 3. preparation method as claimed in claim 1 is characterized in that, in step S1, the volume ratio of DMF and water is 5:(0.5-2). 4 . The preparation method according to claim 1 , wherein, in step S1 , the Eu-MOF crystals are prepared by vacuum drying at a temperature of 50-80° C. for 5-10 hours. 5 . 5. preparation method as claimed in claim 1 is characterized in that, in step S2, the volume of DMF solution is 5-20ml, and the stirring time of DMF solution of Eu-MOF crystal and PbBr ₂ is 6-24h. 6. The preparation method of claim 1, wherein in step S2, the molar ratio of CsBr to PbBr ₂ is 1:1. 7. The preparation method of claim 1, wherein in step S3, the volume ratio of the mixed precursor solution of the prepared CsBr and PbBr ₂ @Eu-MOF to toluene is (0.1-2):10. 8 . The preparation method according to claim 1 , wherein the perovskite quantum dot/Eu-MOF composite light-emitting material prepared by the preparation method is used in LEDs. 9 . 9. preparation method as claimed in claim 8 is characterized in that, perovskite quantum dot/Eu-MOF composite luminescent material is mixed with ultraviolet curing glue, drip-coating on blue LED chip, after curing under ultraviolet light, Get white LEDs.

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