Rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystal and preparation method and application thereof

Abstract

The invention relates to the technical field of flexible materials, in particular to a rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystal and a preparation method and application thereof, and the rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystal prepared by the preparation method of the rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystal provided by the invention has the characteristics of no toxicity and good stability. According to the preparation method of the rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystal provided by the invention, non-toxic gadolinium acetylacetonate is selected as a rare earth source, and the 4f electron energy level of gadolinium ions in the rare earth source can be coupled with the band gap of perovskite, so that the luminous efficiency or light absorption capacity of the material is improved. The Rb3GdCl6 zero-dimensional nanocrystal can be formed after trimethylchlorosilane is injected under a variable-temperature condition, the Rb3GdCl6 zero-dimensional nanocrystal is a spherical nanocrystal, and the spherical nanocrystal has lower surface energy compared with a cubic nanocrystal, so that the spherical nanocrystal is more stable compared with nanocrystals in other shapes.

Description

Technical Field

[0001] The present invention relates to the technical field of metal halide perovskite materials, in particular to a rare earth zero-dimensional gadolinium-based halide perovskite nanocrystal and a preparation method and application thereof. Background Art

[0002] With the rapid development of science and technology and industrial production in recent years, people have become more demanding about quality of life and living environment. They are eager to develop new functional materials and technologies to address issues such as fossil energy shortages, environmental pollution, and global warming. Therefore, the development of high-efficiency, environmentally friendly, energy-saving, and emission-reducing luminescent materials is of paramount importance. This is why more and more scientists are turning their attention to perovskites.

[0003] Metal halide perovskites, with their exceptional optoelectronic properties (high luminescence efficiency, long carrier dispersion distances, and large absorption cross-sections), are widely used and studied in applications such as lighting, photodetection, lasers, and photocatalysis. Lead-based halide perovskites, among others, exhibit exceptional photophysical properties and device performance. However, the toxicity of lead and the instability of lead-based halide perovskites have hindered their further commercialization. Therefore, it is imperative to develop non-toxic and stable zero-dimensional gadolinium-based halide perovskite nanocrystals to replace toxic lead-based halide perovskites. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystal and its preparation method and application, which solves the above-mentioned technical problems and can prepare low-toxic or non-toxic and stable rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals.

[0005] To solve the above technical problems, the present invention provides a method for preparing rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals, comprising the following steps: dissolving gadolinium acetylacetonate and rubidium acetate in a mixed solvent to obtain a mixed solution A, wherein the mixed solvent is a mixture of octadecene, oleic acid and oleylamine; heating the mixed solution A at 100° C. to 120° C., and simultaneously performing a vacuum treatment on the mixed solution A at the temperature until no bubbles are generated in the mixed solution A, then stopping the vacuum treatment, then heating the mixed solution A at 200° C. to 220° C. for 5 to 10 minutes, then reducing the heating temperature from 200° C. to 220° C. to 160° C. to 180° C., and injecting trimethylsilyl chloride at 160° C. to 180° C., then heating to 230° C. to 250° C., heating for 5 to 10 minutes, and then cooling to below 100° C. and performing an ice-water bath cooling treatment to obtain a zero-dimensional gadolinium-based halide perovskite nanocrystal precipitate; The zero-dimensional gadolinium-based halide perovskite nanocrystal precipitate is centrifugally washed multiple times to obtain pure rare earth zero-dimensional gadolinium-based halide perovskite nanocrystals.

[0006] Preferably, the molar volume ratio of gadolinium acetylacetonate to octadecene, oleic acid and oleylamine is (0.5-1.0) mmol: (5-10) ml: (2.5-5) ml: (0.8-1.6) ml.

[0007] Preferably, the molar volume ratio of rubidium acetate to octadecene, oleic acid and oleylamine is (1.5-3) mmol: (5-10) ml: (2.5-5) ml: (0.8-1.6) ml.

[0008] Preferably, during the vacuum treatment, the heating temperature of the mixed solution A is 100° C. to 120° C., and the vacuum treatment time is 1 hour to 2 hours. The main purpose is to remove water from the mixed solution A.

[0009] Preferably, the injection rate of methylchlorosilane is 0.1 ml / min to 0.5 ml / min. The injection rate of methylchlorosilane can effectively control the speed of forming nanocrystals.

[0010] Preferably, the steps of centrifuging and washing the rare earth zero-dimensional gadolinium-based halide perovskite nanocrystal precipitate multiple times are: Transfer the rare earth zero-dimensional gadolinium-based halide perovskite nanocrystal precipitate to a centrifuge tube and centrifuge. Remove the upper waste liquid and retain the precipitate. Then add n-hexane to the centrifuge tube and disperse it using an ultrasonic machine or oscillator. Then centrifuge again to remove the upper waste liquid and retain the precipitate. Then add n-hexane and disperse the precipitate into the solution using an ultrasonic machine or oscillator. Then centrifuge and wash it. This is used to centrifuge and wash the synthesized nanocrystals to remove excess organic matter or solvent. Centrifugation is used to precipitate the washed nanocrystals. Then, ultrasound is used to disperse the precipitate into the solvent. Then, washing is done. The final ultrasound is used to disperse it.

[0011] The invention provides a preparation method of rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals and the prepared rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals.

[0012] The present invention provides the application of rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals in the preparation of high-efficiency photoelectric devices.

[0013] Compared with the prior art, the present invention has the following beneficial effects: The method for preparing rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals provided by the present invention has the characteristics of being non-toxic and having good stability. In the method for preparing rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals provided by the present invention, non-toxic gadolinium acetylacetonate is selected as the rare earth source. The 4f electron energy level of gadolinium ions in the rare earth source can couple with the band gap of the perovskite, thereby improving the luminous efficiency or light absorption capacity of the material. After the injection of trimethylchlorosilane under variable temperature conditions, Rb3GdCl6 zero-dimensional nanocrystals are formed, such as Figure 3 The spherical nanocrystals shown have lower surface energy than cubic nanocrystals and are therefore more stable than nanocrystals of other shapes.

[0014] Due to the low solubility of gadolinium acetylacetonate and rubidium acetate, octadecene, oleic acid, and oleylamine are used to dissolve the gadolinium acetylacetonate and rubidium acetate to prepare a mixed solution A, which is a prerequisite for the synthesis of rare earth zero-dimensional gadolinium-based halide perovskite nanocrystals. The prepared mixed solution A is heated under vacuum conditions to remove air and water from the mixed solution A, thereby preventing the effects of water and air on the synthesis of rare earth zero-dimensional gadolinium-based halide perovskite nanocrystals. The reaction temperature is then adjusted and trimethylsilyl chloride is added dropwise to promote the nucleation of the rare earth zero-dimensional gadolinium-based halide perovskite nanocrystals, forming a rare earth zero-dimensional gadolinium-based halide perovskite nanocrystal precipitate. No lead-based halide is used in the preparation process, making the rare earth zero-dimensional gadolinium-based halide perovskite nanocrystal precipitate non-toxic. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is the crystal structure diagram of rare earth zero-dimensional gadolinium-based halide perovskite nanocrystals (Rb3GdCl6 nanocrystals).

[0016] Figure 2 This is the X-ray powder diffraction pattern (P-XRD) of rare earth zero-dimensional gadolinium-based halide perovskite nanocrystals (Rb3GdCl6 nanocrystals).

[0017] Figure 3 This is the cold-field transmission electron microscopy (TEM) morphology of rare earth zero-dimensional gadolinium-based halide perovskite nanocrystals (Rb3GdCl6 nanocrystals).

[0018] Figure 4 Fluorescence excitation and emission spectra of rare earth zero-dimensional gadolinium-based halide perovskite nanocrystals (Rb3GdCl6 nanocrystals).

[0019] Figure 5 This is the fluorescence decay curve of rare earth zero-dimensional gadolinium-based halide perovskite nanocrystals (Rb3GdCl6 nanocrystals). DETAILED DESCRIPTION

[0020] In order to make the above-mentioned purposes, features and advantages of the embodiments of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0021] The inventors have discovered that rare earth-based halide perovskite materials are important, high-performance lead-free metal halide perovskite materials that can replace toxic lead ions to develop non-toxic lead-free metal halide perovskite nanocrystals.

[0022] In view of this, the present invention provides a rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystal and its preparation method and application, which solves the above technical problems and can prepare low-toxic or non-toxic and stable rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals.

[0023] It should be noted that when the present invention involves a numerical range, it should be understood that the two endpoints of each numerical range and any numerical value between the two endpoints can be selected. Since the steps and methods used are the same as those in Examples 1 to 3, in order to avoid redundancy, the present invention describes a preferred embodiment, but the present invention is not limited thereto, but can also be specifically implemented in other ways within the scope of the technical solution defined in the attached claims.

[0024] The technical solution of the present invention is further illustrated below in the form of specific examples.

[0025] Example 1 A method for preparing rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals comprises the following steps: 0.5 mmol of gadolinium acetylacetonate Gd(acac)3, 1.5 mmol of rubidium acetate RbAc, 5 ml of octadecene, 2.5 ml of oleic acid, and 0.8 ml of oleylamine were weighed and placed in a 50 ml two-necked round-bottom flask to obtain a mixed solution A; The two-necked round-bottom flask containing the mixed solution A was vacuumed for 1 hour, and during the vacuuming, it was placed in a heating mantle at 120°C and heated until there were no bubbles in the two-necked round-bottom flask; The temperature of the heat exchanger was then raised from 120°C to 200°C, held at 200°C for 5 minutes, and then lowered to 180°C. Trimethylchlorosilane (as a halogen source) was injected at a rate of 0.1 ml / min. The temperature was then raised to 230°C and held for 5 minutes. The temperature was then lowered to below 100°C and placed in an ice-water bath to obtain a zero-dimensional gadolinium-based halide perovskite nanocrystal precipitate.

[0026] Transfer the synthesized zero-dimensional gadolinium-based halide perovskite nanocrystal precipitate to a 20ml centrifuge tube and centrifuge at 11,000 r / min for 10 minutes. Remove the upper waste liquid and retain the precipitate. Add 5ml of n-hexane to the centrifuge tube, disperse it using an ultrasonic device or oscillator, and then centrifuge at 11,000 r / min for 10 minutes. Remove the upper waste liquid (this step is to wash away excess residual reaction solvent) and retain the precipitate; add 5ml of n-hexane to disperse the precipitate into the solution, and centrifuge at 5,000 r / min for 5 minutes to obtain Rb3GdCl6 perovskite nanocrystals.

[0027] Example 2 A method for preparing rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals comprises the following steps: 0.8 mmol of gadolinium acetylacetonate Gd(acac)3, 2.0 mmol of rubidium acetate RbAc, 8 ml of octadecene, 4 ml of oleic acid, and 1.0 ml of oleylamine were weighed and placed in a 50 ml two-necked round-bottom flask to obtain a mixed solution A; The two-necked round-bottom flask containing the mixed solution A was vacuumed for 1.5 hours and placed in a heating mantle at 100°C for heating until no bubbles were left in the two-necked round-bottom flask; The temperature of the heat exchanger was then raised from 100°C to 210°C, held at 210°C for 8 minutes, and then lowered to 160°C. Trimethylchlorosilane (as a halogen source) was injected at a rate of 0.3 ml / min. The temperature was then raised to 240°C and held for 8 minutes. The temperature was then lowered to below 80°C and placed in an ice-water bath to obtain a zero-dimensional gadolinium-based halide perovskite nanocrystal precipitate.

[0028] Transfer the synthesized zero-dimensional gadolinium-based halide perovskite nanocrystal precipitate to a 20ml centrifuge tube and centrifuge at 11,000 r / min for 10 minutes. Remove the upper waste liquid and retain the precipitate. Add 5ml of n-hexane to the centrifuge tube, disperse it using an ultrasonic device or oscillator, and then centrifuge at 11,000 r / min for 10 minutes. Remove the upper waste liquid (this step is to wash away excess residual reaction solvent) and retain the precipitate; add 5ml of n-hexane to disperse the precipitate into the solution, and centrifuge at 5,000 r / min for 5 minutes to obtain Rb3GdCl6 perovskite nanocrystals.

[0029] Example 3 A method for preparing rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals comprises the following steps: 1.0 mmol of gadolinium acetylacetonate Gd(acac)3, 3.0 mmol of rubidium acetate RbAc, 10 ml of octadecene, 5.0 ml of oleic acid, and 1.6 ml of oleylamine were placed in a 50 ml two-necked round-bottom flask to obtain a mixed solution A; The two-necked round-bottom flask containing the mixed solution A was vacuumed for 2.0 hours and placed in a heating mantle at 110°C for heating until no bubbles were left in the two-necked round-bottom flask; The heating mantle temperature was then raised from 110°C to 220°C, held at 220°C for 10 minutes, and then lowered to 170°C. Trimethylchlorosilane (as a halogen source) was injected at a rate of 0.5 ml / min, and then the temperature was raised to 250°C and held for 10 minutes. The temperature was then slowly lowered to below 90°C and placed in an ice-water bath to obtain a zero-dimensional gadolinium-based halide perovskite nanocrystal precipitate.

[0030] Transfer the synthesized zero-dimensional gadolinium-based halide perovskite nanocrystal precipitate to a 20ml centrifuge tube and centrifuge at 11,000 r / min for 10 minutes. Remove the upper waste liquid and retain the precipitate. Add 5ml of n-hexane to the centrifuge tube, disperse it using an ultrasonic device or oscillator, and then centrifuge at 11,000 r / min for 10 minutes. Remove the upper waste liquid (this step is to wash away excess residual reaction solvent) and retain the precipitate; add 5ml of n-hexane to disperse the precipitate into the solution, and centrifuge at 5,000 r / min for 5 minutes to obtain Rb3GdCl6 perovskite nanocrystals.

[0031] Examples 1 to 3 all prepared rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals. The performance of any one of the rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals prepared in Example 1 and Example 3 is analyzed below.

[0032] Experimental verification of the present invention: (1) Crystal structure diagram pass Figure 1 The crystal structure of the rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystal is shown in Figure 1. -3 The octahedral structure, with rubidium at the center, forms isolated zero-dimensional rare earth metal halide perovskite nanocrystals. However, these nanocrystals typically have a large bandgap due to the strong restriction of electron movement within their isolated octahedral or cluster structure. This large bandgap makes these zero-dimensional rare earth halide perovskite nanocrystals potentially useful in optoelectronic devices, such as ultraviolet light detection or blue light emission.

[0033] (2) X-ray powder diffraction pattern pass Figure 2 The X-ray powder diffraction pattern of rare earth zero-dimensional gadolinium-based halide perovskite nanocrystals is given by Figure 2 It can be seen that Rb3GdCl6 nanocrystals were successfully synthesized.

[0034] (3) Cold-field transmission electron microscopy (TEM) Figure 3 Cold-field transmission electron microscopy of rare earth zero-dimensional gadolinium-based halide perovskite nanocrystals is given. Figure 3 The synthesized rare earth zero-dimensional gadolinium-based halide perovskite nanocrystals are spherical. Spherical rare earth nanoparticles tend to maintain this morphology due to their lower surface energy, thus reducing the total energy of the system. However, the presence of high surface energy at the corners and flat surfaces of cubic nanocrystals creates a high degree of atomic coordination unsaturation, making them susceptible to reactions with the external environment (such as solvents and gas molecules), leading to structural distortion or dissolution. Spherical nanocrystals, on the other hand, have a more uniform coordination environment for surface atoms, resulting in a more balanced surface energy distribution, making surface atomic desorption or chemical reactions less likely, and thus more stable.

[0035] (IV) Fluorescence excitation and emission spectra Figure 4 The fluorescence excitation and emission spectra of rare earth zero-dimensional gadolinium-based halide perovskite nanocrystals are given by Figure 4 It can be seen that this rare earth zero-dimensional gadolinium-based halide perovskite nanocrystal exhibits a deep blue narrow-band emission peak at 420nm under 390nm excitation. This narrow-band emission may originate from the radiation of free excitons (FE).

[0036] (V) Fluorescence decay curve Figure 5 The fluorescence decay curve of rare earth zero-dimensional gadolinium-based halide perovskite nanocrystals is given by Figure 5 As we can see, we tested the time-resolved fluorescence spectrum of the blue light emission in the above figure, which showed a short lifetime of single exponential decay with an average decay lifetime of 3.8ns, further verifying our above speculation that its deep blue light emission at 420nm mainly comes from free excitons (FE).

[0037] Obviously, those skilled in the art may make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations fall within the scope of the claims and their equivalents, the present invention is intended to include such modifications and variations.

Claims

1. A method for preparing rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals, characterized in that: The steps include: dissolving gadolinium acetylacetonate and rubidium acetate in a mixed solvent to obtain a mixed solution A, wherein the mixed solvent is a mixture of octadecene, oleic acid and oleylamine; heating the mixed solution A at 100° C. to 120° C., and simultaneously performing a vacuum treatment on the mixed solution A at the temperature until no bubbles are generated in the mixed solution A, then stopping the vacuum treatment, then heating the mixed solution A at 200° C. to 220° C. for 5 to 10 minutes, then reducing the heating temperature from 200° C. to 220° C. to 160° C. to 180° C., and injecting trimethylsilyl chloride at 160° C. to 180° C., then heating to 230° C. to 250° C., heating for 5 to 10 minutes, and then cooling to below 100° C. and performing an ice-water bath cooling treatment to obtain a zero-dimensional gadolinium-based halide perovskite nanocrystal precipitate; The zero-dimensional gadolinium-based halide perovskite nanocrystal precipitate is centrifugally washed multiple times to obtain pure rare earth zero-dimensional gadolinium-based halide perovskite nanocrystals.

2. The method for preparing rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals according to claim 1, characterized in that: The molar volume ratio of gadolinium acetylacetonate to octadecene, oleic acid and oleylamine is (0.5-1.0) mmol: (5-10) ml: (2.5-5) ml: (0.8-1.6) ml.

3. The method for preparing rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals according to claim 1, characterized in that: The molar volume ratio of the rubidium acetate to octadecene, oleic acid and oleylamine is (1.5-3) mmol: (5-10) ml: (2.5-5) ml: (0.8-1.6) ml.

4. The method for preparing rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals according to claim 1, characterized in that: During the vacuum treatment, the heating temperature of the mixed solution A is 100° C. to 120° C., and the vacuum treatment time is 1 h to 2 h.

5. The method for preparing rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals according to claim 1, characterized in that: The injection rate of methylchlorosilane is 0.1ml / min~0.5ml / min.

6. The method for preparing rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals according to claim 1, characterized in that: The steps of performing multiple centrifugal washing on the rare earth zero-dimensional gadolinium-based halide perovskite nanocrystal precipitate are as follows: The rare earth zero-dimensional gadolinium-based halide perovskite nanocrystal precipitate is centrifuged, the upper waste liquid is removed and the precipitate is retained, then n-hexane is added and dispersed by ultrasound or oscillation, then centrifuged again to remove the upper waste liquid and retain the precipitate, then n-hexane is added and the precipitate is dispersed into the solution by ultrasound or oscillation, and then centrifuged for cleaning.

7. Rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals prepared by the method for preparing rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystals according to any one of claims 1 to 6.

8. Use of the rare earth zero-dimensional gadolinium-based halogen perovskite nanocrystal according to claim 7 in the preparation of high-efficiency optoelectronic devices.

Images