CN109456763B - A kind of synthetic method of lead-iodine perovskite quantum dots - Google Patents

Abstract

A method for synthesizing lead-iodine perovskite quantum dots relates to the synthesis of quantum dots. After mixing at least one of Cs ₂ CO ₃ , methylamine and formamidine acetate, oleic acid and octadecene according to a stoichiometric ratio, nitrogen was introduced, the temperature was raised, and then cooled to room temperature for subsequent use; PbO was mixed with oleic acid and ten After the octaene was mixed according to the stoichiometric ratio, nitrogen was introduced, and the temperature was increased until the PbO powder was dissolved, and then cooled to room temperature for subsequent use; after preheating the obtained solution, it was mixed with oleylamine and octadecene solution respectively, and the mixed solution was heated to 50 °C. ～300° C., then adding trimethyl iodide silane, after the reaction, cooling the reaction device with an ice-water bath, and the obtained solution is the lead-iodine perovskite quantum dots. The obtained lead-iodine perovskite quantum dots possess high fluorescence quantum efficiency and stability. Such high-performance and stable lead-iodide perovskite quantum dots facilitate future display and lighting applications. The operation is simple, the raw materials are easy to obtain, and it is easy to be popularized and applied on a large scale.

Description

A kind of synthetic method of lead-iodine perovskite quantum dots

technical field

The invention relates to the synthesis of quantum dots, in particular to a synthesis method of lead-iodine perovskite quantum dots.

Background technique

Lead-halide perovskite quantum dots have received extensive attention in recent years, owing to their high fluorescence quantum efficiency, high color purity, and tunable emission color over the entire visible light range. Compared with traditional cadmium-based chalcogenide quantum dots, lead-halide perovskite quantum dots also have low preparation temperature and high defect tolerance. These excellent properties enable lead-halide perovskite quantum dots to be used in many fields, such as light-emitting diodes, lasers, photodetectors, and photocatalysis. However, their practical application is greatly limited by poor chemical and structural stability (ACS Energy Lett., 2017, 2(9), 2071–2083). In particular, red fluorescent lead-iodine perovskite quantum dots, in addition to being sensitive to light, oxygen, water, and high temperature, have an optically active perovskite phase that can only exist at room temperature for a few weeks. Recent studies have shown that an iodine-rich synthetic environment helps improve the stability of lead-iodide perovskite quantum dots (Chem. Mater., 2017, 29(12), 5168–5173), which is derived from this environment The resulting iodine-rich surface structure can induce lattice stress and increase the difficulty of phase transition. However, the current synthesis method is highly dependent on lead iodide as the raw material, and the ratio of iodide ion/lead ion in the reaction system is only 2, which is far lower than the standard stoichiometric ratio of 3. Therefore, in order to further increase the ratio of iodide ion/lead ion in the reaction system to obtain more stable lead-iodide perovskite quantum dots, it is necessary to develop a new synthesis method.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a synthesis method capable of obtaining stable lead-iodide perovskite quantum dots in view of the problems raised by the above-mentioned background technology.

The present invention uses trimethyl iodide silane as raw material, and its steps are as follows:

1) after mixing at least one of Cs ₂ CO ₃ , methylamine and formamidine acetate, oleic acid and octadecene according to the stoichiometric ratio, feed nitrogen, heat up, and then cool to room temperature for subsequent use;

In step 1), the temperature for heating may be 80-120° C., and the time for heating may be 1 h.

2) after mixing PbO with oleic acid and octadecene according to the stoichiometric ratio, feed nitrogen, heat up until the PbO powder dissolves, and be cooled to room temperature for subsequent use;

In step 2), the temperature for increasing the temperature may be 120°C.

3) After preheating the solutions obtained in steps 1) and 2), mix with oleylamine and octadecene solution respectively, heat the mixed solution to 50-300°C, then add trimethyliodosilane, and after the reaction, use The reaction device is cooled in an ice-water bath, and the obtained solution is the lead-iodine perovskite quantum dots.

In step 3), the temperature of the preheating may be 80°C.

The molar ratio of Cs ₂ CO ₃ : methylamine: formamidine acetate: PbO: oleic acid: oleylamine: trimethyliodosilane is (0～1):(0～1):(0～1):1 :(1～10):(1～10):(2～10).

The lead-iodine perovskite quantum dots prepared by the invention have high fluorescence quantum efficiency (above 90%) and stability. Such high-performance and stable lead-iodide perovskite quantum dots facilitate future display and lighting applications. In addition, the operation of the invention is simple, the raw materials are easily obtained, and it is easy to be popularized and applied on a large scale.

The present invention is to inject trimethyliodosilane into octadecene containing at least one of Cs ₂ CO ₃ , methylamine and formamidine acetate, PbO, oleic acid and oleylamine, and the synthesized quantum dots have nearly 100% high fluorescence quantum yield, while exhibiting high room temperature storage stability. The invention can further improve the performance of lead-iodine perovskite quantum dots, which is helpful for future display and lighting applications.

Description of drawings

Fig. 1 is the fluorescence and ultraviolet-visible absorption spectra of the sample obtained in Example 1 of the present invention.

FIG. 2 is the XRD patterns of the samples obtained in Example 1 of the present invention when placed for different days.

FIG. 3 is a TEM image of the sample obtained in Example 1 of the present invention.

Detailed ways

The following embodiments will further illustrate the present invention in conjunction with the accompanying drawings.

Comparative Example 1

Weigh 0.2035g of cesium carbonate, add 0.625mL of oleic acid and 10mL of octadecene into a 100mL flask, pass nitrogen, heat to 120°C until the cesium carbonate is completely dissolved, and then cool to room temperature for later use. Weigh 0.087g lead iodide, add 0.5mL oleic acid, 0.5mL oleylamine and 5mL octadecene into a 100mL flask, pass nitrogen, heat to 120°C until the lead iodide is completely dissolved, then heat up to 150°C, inject quickly 0.4 mL of preheated cesium oleate solution, cooled in an ice-water bath after 5 s. The fluorescence of this sample completely disappeared after 5 days.

Example 1

Mix Cs ₂ CO ₃ (analytical grade) and oleic acid (analytical grade) according to the stoichiometric ratio of 1:3, then add 5 mL of octadecene (analytical grade), pass nitrogen, and heat the mixture to 120°C until the powder is completely dissolved After cooling to room temperature. The Cs ion concentration in the obtained solution was 5.0 mol/42.5 mL. PbO (analytical grade) and oleic acid were mixed at a stoichiometric ratio of 1:3, then 5 mL of octadecene was added, nitrogen was introduced, and the mixture was heated to 120° C. until the powder was completely dissolved, and then cooled to room temperature. The concentration of Pb ions in the obtained solution was 1.0 mol/L. After the above two solutions were preheated at 80°C, 0.4mL and 0.5mL were respectively mixed with 0.4mL oleylamine and 5mL octadecene, the mixture was heated to 150°C, and then 0.2mL trimethyliodosilane was rapidly injected to react. After 5 s, the device was cooled with an ice-water bath, and the obtained solution was the crude product of CsPbI ₃ perovskite quantum dots.

The material obtained in Example 1 was characterized by fluorescence spectroscopy and ultraviolet-visible absorption spectrometer, and the results are shown in FIG. 1 . The XRD pattern of Example 1 is shown in Figure 2. It can be seen from the figure that the XRD pattern of the obtained sample is consistent with the card numbered 161481 in the Inorganic Crystal Structure Database (ICSD), which proves that it is a cubic phase crystal structure and can be unchanged for 43 days. The TEM image of Example 1 is shown in FIG. 3 , from which it can be seen that the single particle size of the obtained sample is ~11 nm.

Example 2

Mix Cs ₂ CO ₃ (analytical grade) and oleic acid (analytical grade) according to the stoichiometric ratio of 1:3, then add 5 mL of octadecene (analytical grade), pass nitrogen, and heat the mixture to 120°C until the powder is completely dissolved After cooling to room temperature. The Cs ion concentration in the obtained solution was 5.0 mol/42.5 mL. PbO (analytical grade) and oleic acid were mixed at a stoichiometric ratio of 1:3, then 5 mL of octadecene was added, nitrogen was introduced, and the mixture was heated to 120° C. until the powder was completely dissolved, and then cooled to room temperature. The concentration of Pb ions in the obtained solution was 1.0 mol/L. After the above two solutions were preheated at 80°C, 0.4mL and 0.5mL were respectively mixed with 0.5mL oleylamine and 5mL octadecene, the mixture was heated to 150°C, and then 0.2mL trimethyliodosilane was rapidly injected to react. After 5 s, the device was cooled with an ice-water bath, and the obtained solution was the crude product of CsPbI ₃ perovskite quantum dots.

Example 3

Mix Cs ₂ CO ₃ (analytical grade) and oleic acid (analytical grade) according to the stoichiometric ratio of 1:2, then add 5 mL of octadecene (analytical grade), pass nitrogen, and heat the mixture to 120°C until the powder is completely dissolved After cooling to room temperature. The Cs ion concentration in the obtained solution was 5.0 mol/42.5 mL. PbO (analytical grade) and oleic acid were mixed in a stoichiometric ratio of 1:2, then 5 mL of octadecene was added, nitrogen was introduced, and the mixture was heated to 120° C. until the powder was completely dissolved, and then cooled to room temperature. The concentration of Pb ions in the obtained solution was 1.0 mol/L. After the above two solutions were preheated at 80°C, 0.4mL and 0.5mL were respectively mixed with 0.4mL oleylamine and 5mL octadecene, the mixture was heated to 150°C, and then 0.2mL trimethyliodosilane was rapidly injected to react. After 5 s, the device was cooled with an ice-water bath, and the obtained solution was the crude product of CsPbI ₃ perovskite quantum dots.

Example 4

Formamidine acetate (analytical grade) and oleic acid (analytical grade) were mixed in a stoichiometric ratio of 1:3, then 5 mL of octadecene (analytical grade) was added, nitrogen was introduced, and the mixture was heated to 80°C until the powder was completely dissolved. Cool to room temperature. The formamidine ion concentration in the obtained solution was 5.0 mol/42.5 mL. PbO (analytical grade) and oleic acid were mixed at a stoichiometric ratio of 1:3, then 5 mL of octadecene was added, nitrogen was introduced, and the mixture was heated to 120° C. until the powder was completely dissolved, and then cooled to room temperature. The concentration of Pb ions in the obtained solution was 1.0 mol/L. After the above two solutions were preheated at 80°C, 0.4mL and 0.5mL were respectively mixed with 0.4mL oleylamine and 5mL octadecene, the mixture was heated to 80°C, and then 0.2mL trimethyliodosilane was rapidly injected to react. After 5s, the device was cooled with an ice-water bath, and the obtained solution was the crude product of formamidine lead iodide perovskite quantum dots.

Example 5

Methylamine and oleic acid (analytical grade) with a concentration of 30-33 wt.% were mixed according to the stoichiometric ratio of 1:3 (methylamine:oleic acid), then 5 mL of octadecene (analytical grade) was added, and nitrogen was introduced, and heated The mixture was heated to 80°C, reacted for 1 h and cooled to room temperature. The methylamine cation concentration in the obtained solution was 5.0 mol/42.5 mL. PbO (analytical grade) and oleic acid were mixed in a stoichiometric ratio of 1:3, then 5 mL of octadecene was added, nitrogen was introduced, and the mixture was heated to 80° C. until the powder was completely dissolved, and then cooled to room temperature. The concentration of Pb ions in the obtained solution was 1.0 mol/L. After the above two solutions were preheated at 80°C, 0.4mL and 0.5mL were respectively mixed with 0.4mL oleylamine and 5mL octadecene, heated to 80°C, and then 0.2mL trimethyliodosilane was rapidly injected to react. After 5s, the device was cooled with an ice-water bath, and the obtained solution was the crude product of methylamine lead iodide perovskite quantum dots.

Claims (1)

1. a synthetic method of lead-iodine perovskite quantum dot is characterized in that its steps are as follows: 1) after mixing at least one of Cs ₂ CO ₃ , methylamine and formamidine acetate, oleic acid and octadecene according to the stoichiometric ratio, feed nitrogen, heat up, and then cool to room temperature for subsequent use; the temperature of the temperature rise The temperature is 80～120℃, and the heating time is 1h; 2) after PbO is mixed with oleic acid and octadecene according to the stoichiometric ratio, nitrogen is introduced, and the temperature is heated until the PbO powder is dissolved, and it is cooled to room temperature for subsequent use; the temperature of the temperature rise is 120 ° C; 3) After preheating the solution obtained in steps 1) and 2), mix with oleylamine and octadecene solution respectively, heat up the mixed solution, then add trimethyliodosilane, after the reaction, cool the reaction device with an ice-water bath , the obtained solution is lead-iodine perovskite quantum dots; The molar ratio of Cs ₂ CO ₃ : methylamine: formamidine acetate: PbO: oleic acid: oleylamine: trimethyliodosilane is (0～1):(0～1):(0～1):1 :(1～10):(1～10):(2～10); The preheating temperature is 80°C; the heating temperature is 50-300°C.

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