阅读说明：本技术 双溴季铵盐配体及用于铅卤钙钛矿纳米晶溶液的合成方法 (Double-bromine quaternary ammonium salt ligand and synthesis method for lead-halogen perovskite nanocrystalline solution ) 是由 解荣军 蔡宇廷 于 2021-09-18 设计创作，主要内容包括：双溴季铵盐配体及用于铅卤钙钛矿纳米晶溶液的合成方法,涉及纳米晶合成。使用所述双溴季铵盐配体作为合成用的配体,1)将卤化铯、卤化甲脒和卤化甲胺中的至少一种与卤化铅、N,N-二甲基甲酰胺按比例混合,随后超声分散,放于室温下备用；2)在步骤1)所得溶液中加入双溴季铵盐配体,超声分散：3)取步骤2)所得溶液注射至甲苯溶液中,即合成铅卤钙钛矿纳米晶溶液。制备得到的铅卤钙钛矿纳米晶拥有高的荧光量子效率(90％以上)和优良的稳定性,有助于未来的显示和照明应用。具有操作简单,无惰性氛围保护和加热处理,且原料易得,易于大规模推广应用。(A double-bromine quaternary ammonium salt ligand and a synthetic method for a lead-halogen perovskite nanocrystalline solution relate to nanocrystalline synthesis. Using the bisbromoquaternary ammonium salt ligand as a ligand for synthesis, 1) mixing at least one of cesium halide, formamidine halide and methylamine halide with lead halide and N, N-dimethylformamide in proportion, then ultrasonically dispersing, and placing at room temperature for later use; 2) adding a bisbromoquaternary ammonium salt ligand into the solution obtained in the step 1), and performing ultrasonic dispersion: 3) and (3) injecting the solution obtained in the step 2) into a toluene solution to synthesize the lead-halogen perovskite nanocrystalline solution. The prepared lead-halogen perovskite nanocrystalline has high fluorescence quantum efficiency (more than 90 percent) and excellent stability, and is beneficial to future display and illumination applications. The method has the advantages of simple operation, no inert atmosphere protection and heating treatment, easily obtained raw materials and easy large-scale popularization and application.)

1. The bisbromoquaternary ammonium salt ligand is characterized in that the molecular structure is as follows:

2. a method for synthesizing a lead-halogen perovskite nanocrystal solution using the bisbromoquaternary ammonium salt ligand as defined in claim 1 as a ligand for synthesis, characterized by comprising the steps of:

1) mixing at least one of cesium halide, formamidine halide and methylamine halide with lead halide and N, N-dimethylformamide in proportion, and then ultrasonically dispersing the mixture to be placed at room temperature for later use;

2) adding a bisbromoquaternary ammonium salt ligand into the solution obtained in the step 1), and performing ultrasonic dispersion:

3) and (3) injecting the solution obtained in the step 2) into a toluene solution to synthesize the lead-halogen perovskite nanocrystalline solution.

3. The method for synthesizing the lead-halogen perovskite nanocrystal solution as defined in claim 2, wherein in the step 1), the amount of the lead halide is 50 to 80% of the total amount of the lead halide, cesium halide, methylamine halide and methylamine halide.

4. The method for synthesizing a lead-halogen perovskite nanocrystal solution as claimed in claim 2, wherein in the step 1), the mass concentration of the lead halide is 0.1 to 0.3mmol/5 mL.

5. The method for synthesizing the lead-halogen perovskite nanocrystal solution as defined in claim 2, wherein in the step 2), the mass concentration of bromide in the added bisbromoquaternary ammonium salt ligand is 1-20 mg/5 mL.

6. The method for synthesizing the lead-halogen perovskite nanocrystal solution as claimed in claim 2, wherein in the step 3), the volume ratio of the solution obtained in the step 2) to the toluene solution is 0.01 to 0.1.

7. The method for synthesizing the lead-halogen perovskite nanocrystal solution as claimed in claim 2, wherein in the step 3), the synthesis temperature is 0 to 60 ℃.

Technical Field

The invention relates to nanocrystal synthesis, in particular to a double-bromine quaternary ammonium salt ligand and a synthesis method for a lead-halogen perovskite nanocrystal solution.

Background

In recent years, lead-halo perovskite nanocrystals have received much attention because of their excellent optical and electrical properties, such as high fluorescence quantum efficiency (greater than 90%), high color purity, and fluorescence color that can be tuned throughout the visible spectrum. Currently, the efficiency of electroluminescent LED devices based on perovskite nanocrystals has exceeded 20% (Nature,2018,562, 245-. In addition, the electroluminescent LED based on the perovskite nanocrystal can achieve higher brightness than the OLED, the preparation method of the perovskite nanocrystal is simple, and the perovskite nanocrystal can be treated by a solution and raw materials are easy to obtain. These all indicate the wide application prospect of perovskite nanocrystals. However, poor stability severely limits their practical application, particularly in the purification of perovskite nanocrystals, which are susceptible to aggregation and precipitation and further degradation upon addition of polar agents (e.g., acetone, ethyl acetate and isopropanol) (adv. funct. mater.,2016,26, 8757-8763). One major reason is the weak surface ligand bonding: both of them have only one binding site, whether oleic acid or oleylamine ligands. On the other hand, the ligands on the surface of the perovskite nanocrystals are still relatively long, typically oleic acid and oleylamine ligands with 18 carbons. This thick layer of organic ligand hinders the injection and extraction of charge, degrading the performance of the optoelectronic device. In combination with the above analysis, it is necessary to develop a series of ligands with multiple binding sites and short molecular chains to improve the stability of perovskite quantum dots and the performance of optoelectronic devices based on the perovskite quantum dots.

Disclosure of Invention

The invention aims to solve the problems in the prior art and provide a double-bromine quaternary ammonium salt ligand which has high stability, high efficiency and a thin organic ligand layer and a synthesis method for a lead-halogen perovskite nanocrystalline solution.

The molecular structure of the bisbromoquaternary ammonium salt ligand is as follows:

a synthetic method of lead halide perovskite nanocrystalline solution uses the bisbromo quaternary ammonium salt ligand as a ligand for synthesis, and the synthetic method specifically comprises the following steps:

1) mixing at least one of cesium halide, formamidine halide and methylamine halide with lead halide and N, N-Dimethylformamide (DMF) in proportion, and then ultrasonically dispersing the mixture at room temperature for later use;

2) adding a bisbromoquaternary ammonium salt ligand into the solution obtained in the step 1), and performing ultrasonic dispersion:

3) and (3) injecting the solution obtained in the step 2) into a toluene solution to synthesize the lead-halogen perovskite nanocrystalline solution.

In the step 1), the amount of the lead halide substance accounts for 50-80% of the total amount of the lead halide, cesium halide, methylamine halide and methylamine halide; the mass concentration of the lead halide is 0.1-0.3 mmol/5 mL.

In the step 2), the mass concentration of bromide in the added bisbromoquaternary ammonium salt ligand is 1-20 mg/5 mL.

In the step 3), the volume ratio of the solution obtained in the step 2) to the toluene solution can be 0.01-0.1, and the synthesis temperature can be 0-60 ℃.

The lead-halogen perovskite nanocrystalline prepared by the invention has high fluorescence quantum efficiency (more than 90 percent) and excellent stability, and is beneficial to future display and illumination application. In addition, the method has the advantages of simple operation, no inert atmosphere protection and heating treatment, easily obtained raw materials and easy large-scale popularization and application.

Drawings

FIG. 1 is a graph showing fluorescence and UV-VIS absorption spectra of the sample obtained in example 1.

Fig. 2 is an XRD pattern of the sample obtained in example 1.

FIG. 3 is a TEM image of the sample obtained in example 1 at different magnifications.

Fig. 4 is a graph showing the change in fluorescence quantum efficiency of the samples obtained in example 1 and comparative example 1 at different washing and purification times.

Detailed Description

The following examples will further illustrate the present invention with reference to the accompanying drawings.

Comparative example 1

Reacting PbBr₂(analytically pure) and CsBr (analytically pure) were mixed at a stoichiometric ratio of 2: 1, followed by addition of 0.066mL Oleylamine (OLA), 0.500mL Oleic Acid (OA) and 5mL N, N-dimethylformamide (DMF, analytically pure), and ultrasonic dispersion was carried out until the powder was completely dissolved. The Cs ion concentration of the resulting solution was 0.1mmol/5.5 mL. Subsequently, 0.15mL of the above solution was quickly injected into 5mL of toluene. The obtained green solution is CsPbBr₃Perovskite nanocrystalline solution. With the addition of 2 volumes of acetone, the solution turned yellow, suggesting that degradation occurred. After thorough mixing, the mixed solution was centrifuged at 11800rpm for 1 min. The supernatant was discarded, and the pellet was dispersed in toluene for storage and characterization.

Example 1

Reacting PbBr₂(analytically pure) and CsBr (analytically pure) were mixed at a stoichiometric ratio of 2: 1, followed by addition of 25mg of N, N' -bis (dodecyldimethyl) ethylenediamine bromide and 5mL of N, N-dimethylformamide (DMF, analytically pure), and ultrasonic dispersion was carried out until the powder was completely dissolved. The Cs ion concentration of the resulting solution was 0.1mmol/5 mL. Subsequently, 0.15mL of the above solution was quickly injected into 5mL of toluene. The obtained green solution is CsPbBr₃Perovskite nanocrystalline solution. The solution remained green with the addition of 2 volumes of acetone. After thorough mixing, the mixed solution was centrifuged at 11800rpm for 1 min. The supernatant was discarded, and the pellet was dispersed in toluene for storage and characterization.

The material obtained in example 1 was characterized by fluorescence spectroscopy and uv-vis absorption spectroscopy, and the results are shown in fig. 1. As shown in fig. 2, the XRD pattern of example 1 shows that the XRD spectrum of the obtained sample is consistent with the card numbered 243735 in the Inorganic Crystal Structure Database (ICSD), which proves that it is an orthorhombic perovskite crystal structure. The TEM image of example 1, as shown in FIG. 3, shows that the morphology of the resulting sample is spherical with a diameter of about 12 nm. As shown in fig. 4, the fluorescence quantum efficiency (PLQY) of the sample in example 1 was still 88.4% after two centrifugal washes, while the sample in comparative example 1 was only 20.8% PLQY.

Example 2

Reacting PbBr₂(analytically pure) and CsBr (analytically pure) were mixed at a stoichiometric ratio of 2: 1, followed by addition of 15mg of N, N' -bis (dodecyldimethyl) ethylenediamine bromide and 5mL of N, N-dimethylformamide (DMF, analytically pure), and ultrasonic dispersion was carried out until the powder was completely dissolved. The Cs ion concentration of the resulting solution was 0.1mmol/5 mL. Subsequently, 0.15mL of the above solution was quickly injected into 5mL of toluene. The obtained green solution is CsPbBr₃Perovskite nanocrystalline solution. The solution remained green with the addition of 2 volumes of acetone. After thorough mixing, the mixed solution was centrifuged at 11800rpm for 1 min. The supernatant was discarded, and the pellet was dispersed in toluene for storage and characterization.

Example 3

Reacting PbBr₂(analytically pure) and CsBr (analytically pure) were mixed at a stoichiometric ratio of 2: 2, followed by addition of 25mg of N, N' -bis (dodecyldimethyl) ethylenediamine bromide and 5mL of N, N-dimethylformamide (DMF, analytically pure), and ultrasonic dispersion was carried out until the powder was completely dissolved. The Cs ion concentration of the resulting solution was 0.2mmol/5 mL. Subsequently, 0.15mL of the above solution was quickly injected into 5mL of toluene. The obtained green solution is CsPbBr₃Perovskite nanocrystalline solution. The solution remained green with the addition of 2 volumes of acetone. After thorough mixing, the mixed solution was centrifuged at 11800rpm for 1 min. The supernatant was discarded, and the pellet was dispersed in toluene for storage and characterization.

Example 4

Reacting PbBr₂(analytically pure) and CsBr (analytically pure) were mixed at a stoichiometric ratio of 2: 1, followed by addition of 25mg of N, N' -bis (dodecyldimethyl) ethylenediamine bromide and 5mL of N, N-dimethylformamide (DMF, analytically pure), and ultrasonic dispersion was carried out until the powder was completely dissolved. The Cs ion concentration of the resulting solution was 0.1mmol/5 mL. Subsequently, 0.15mL of the above solution was quickly injected into 5mL of toluene. The obtained greenThe color solution is CsPbBr₃Perovskite nanocrystalline solution. The solution remained green with the addition of 1 volume of acetone. After thorough mixing, the mixed solution was centrifuged at 11800rpm for 1 min. The supernatant was discarded, and the pellet was dispersed in toluene for storage and characterization.

Example 5

Reacting PbBr₂(analytically pure) and CsBr (analytically pure) were mixed at a stoichiometric ratio of 2: 1, followed by addition of 25mg of N, N' -bis (dodecyldimethyl) ethylenediamine bromide and 5mL of N, N-dimethylformamide (DMF, analytically pure), and ultrasonic dispersion was carried out until the powder was completely dissolved. The Cs ion concentration of the resulting solution was 0.1mmol/5 mL. Subsequently, 0.2mL of the above solution was quickly injected into 5mL of toluene. The obtained green solution is CsPbBr₃Perovskite nanocrystalline solution. The solution remained green with the addition of 2 volumes of acetone. After thorough mixing, the mixed solution was centrifuged at 11800rpm for 1 min. The supernatant was discarded, and the pellet was dispersed in toluene for storage and characterization.