阅读说明：本技术 硝酸钙钝化的高效稳定的立方相CsPbI3纳米晶及其制备方法 (Calcium nitrate passivated high efficiency stable cubic phase CsPbI3Nanocrystalline and preparation method thereof ) 是由 白雪 武秀峰 宋宏伟 董彪 徐琳 徐文 周冬磊 于 2021-09-30 设计创作，主要内容包括：本发明适用于纳米发光材料制备技术领域,提供了硝酸钙钝化的高效稳定的立方相CsPbI-(3)纳米晶及其制备方法,包括以下步骤：把十八烯、油酸以及碳酸铯放在50mL的三颈瓶中,在惰性气体氛围下加热到120℃,并且搅拌至溶液溶解,得到前驱体溶液；将碘化铅、硝酸盐、油酸以及油胺加入到装有十八烯的三颈瓶中,并抽气,之后通入惰性气体,加热到120℃,搅拌得到澄清透明的溶液；升温至170℃,取的前驱体注入到透明溶液里；保持温度在170℃后,快速用冰水浴冷却到室温,接着将步骤三中的混合溶液离心分散到非极性溶剂中,得到CsPbI-(3)纳米晶。此方法操作简单,耗时少,耗能低,具有较高开发价值。(The invention is suitable for the technical field of nano luminescent material preparation, and provides a calcium nitrate passivated high-efficiency stable cubic phase CsPbI 3 The nanocrystalline and the preparation method thereof comprise the following steps: placing octadecene, oleic acid and cesium carbonate in a 50mL three-necked bottle, heating to 120 ℃ under the inert gas atmosphere, and stirring until the solution is dissolved to obtain a precursor solution; adding lead iodide, nitrate, oleic acid and oleylamine into a three-necked bottle filled with octadecene, exhausting, introducing inert gas, heating to 120 ℃, and stirring to obtain a clear and transparent solution; heating to 170 ℃, and injecting the precursor into the transparent solution; keeping the temperature at 170 ℃, quickly cooling to room temperature by using an ice water bath, and then centrifugally dispersing the mixed solution in the third step into a non-polar solvent to obtain CsPbI 3 And (4) nanocrystals. The method is simple to operate, consumes less time, consumes less energy and has higher development value.)

1. Calcium nitrate passivated high efficiency stable cubic phase CsPbI₃The nanocrystalline and the preparation method thereof are characterized by comprising the following steps:

step 1: placing octadecene, oleic acid and cesium carbonate in a 50mL three-necked bottle, heating to 120 ℃ under the inert gas atmosphere, and stirring until the solution is dissolved to obtain a precursor solution;

step 2: adding lead iodide, nitrate, oleic acid and oleylamine into a three-necked bottle filled with octadecene, exhausting, introducing inert gas, heating to 120 ℃, and stirring to obtain a clear and transparent solution;

and step 3: heating to 170 ℃, and injecting the precursor in the step 1 into the transparent solution in the step 2;

and 4, step 4: keeping the temperature at 170 ℃, quickly cooling to room temperature by using an ice water bath, and then centrifugally dispersing the mixed solution in the third step into a non-polar solvent to obtain CsPbI₃And (4) nanocrystals.

2. The calcium nitrate-passivated high efficiency stable cubic phase CsPbI according to claim 1₃The nanocrystalline and the preparation method thereof are characterized in that in the step 1, the volume ratio of octadecene to oleic acid is 10:1, and cesium carbonate is concentratedThe degree was 0.04 g/mL.

3. The calcium nitrate-passivated high efficiency stable cubic phase CsPbI according to claim 1₃The nanocrystalline and the preparation method thereof are characterized in that in the step 1, the stirring speed is 800r/min, and the stirring time is 40 min.

4. The calcium nitrate-passivated high efficiency stable cubic phase CsPbI according to claim 1₃The nanocrystalline and the preparation method thereof are characterized in that in the step 2, the volume ratio of octadecene, oleic acid and oleylamine is 5:1:1, and the molar ratio of nitrate to lead iodide is (0.2-1: 1).

5. The calcium nitrate-passivated high efficiency stable cubic phase CsPbI according to claim 1₃The nanocrystalline and the preparation method thereof are characterized in that in the step 2, the introduced inert gas is N₂The stirring time is 30 min.

6. The calcium nitrate-passivated high efficiency stable cubic phase CsPbI according to claim 1₃The nanocrystalline and the preparation method thereof are characterized in that the volume ratio of the precursor to the transparent solution in the step 3 is 1: 14.

7. The calcium nitrate-passivated high efficiency stable cubic phase CsPbI according to claim 1₃The nanocrystalline and the preparation method thereof are characterized in that in the step 4, the precursor is injected into the transparent solution, and the temperature is 170 ℃ and the retention time is 20 seconds.

8. The calcium nitrate-passivated high efficiency stable cubic phase CsPbI according to claim 1₃The nanocrystal and the preparation method thereof are characterized in that in the step 4, the centrifugal rotating speed is 8000-10000r/min, and the nonpolar solvent is cyclohexane.

Technical Field

The invention relates to the technical field of nano luminescent material preparation, in particular to a calcium nitrate passivated high-efficiency stable cubic phase CsPbI₃Nanocrystal and a preparation method thereof.

Background

Cesium lead halide perovskites (CsPbX)₃X ═ Cl, Br, I) is a new semiconductor light emitting material having excellent photoelectric properties such as high photoluminescence quantum yield (PLQYs), adjustable band gap and excellent photoelectric transport properties. Wherein the cubic phase CsPbI₃(α-CsPbI₃) Nanocrystals (NCs) are of great interest because of their small carrier effective mass and narrow direct band gap. However, their high phase stability temperature (over 320 ℃) greatly limits their practical applications. When alpha-CsPbI₃Perovskites readily phase change to form non-photoactive, non-perovskites when exposed to conventional environmental conditions. Thus, highly efficient and stable alpha-CsPbI can be prepared₃Has important significance.

At present, for α -CsPbI₃Little research work has been done on the synthesis and the lack of a highly effective stable alpha-CsPbI for calcium nitrate passivation₃The report of (1). Therefore, in view of the above situation, there is an urgent need to provide calcium nitrate-passivated high-efficiency stable cubic phase CsPbI₃The nanocrystalline and the preparation method thereof are used for overcoming the defects in the current practical application.

Disclosure of Invention

The embodiment of the invention aims to provide efficient and stable cubic phase CsPbI passivated by calcium nitrate₃Nanocrystal and a preparation method thereof.

The embodiment of the invention is realized by the efficient and stable cubic phase CsPbI passivated by calcium nitrate₃The nanocrystalline and the preparation method thereof comprise the following steps:

step 1: putting a certain amount of octadecene, oleic acid and cesium carbonate in a 50mL three-necked bottle, heating to 120 ℃ under an inert gas atmosphere, and stirring until the solution is dissolved to obtain a precursor solution;

step 2: adding lead iodide and nitrate into a three-necked bottle filled with octadecene, exhausting, introducing inert gas, heating to 120 ℃, adding a certain amount of oleic acid and oleylamine, and stirring for a period of time to obtain a clear and transparent solution;

and step 3: heating to 170 ℃, and injecting a certain amount of the precursor in the step 1 into the transparent solution in the step 2;

and 4, step 4: maintaining at 170 deg.C for 20 s, rapidly cooling to room temperature with ice water bath, and centrifuging the mixed solution in step 3 to obtain CsPbI₃And (4) nanocrystals.

As a further scheme of the invention, in the step 1, the volume ratio of octadecene to oleic acid is 10:1, the concentration of cesium carbonate is 0.04g/mL, and the introduced inert gas is N₂。

As a further scheme of the invention, in the step 2, the inert gas is N₂The volume ratio of octadecene, oleic acid and oleylamine is 5:1:1, and the molar ratio of nitrate and lead iodide is (0.2-1: 1).

As a further scheme of the invention, in the step 3, the volume ratio of the precursor to the transparent solution is 1: 14.

As a further scheme of the invention, in the step 4, the centrifugal rotation speed is 8000-10000r/min, and the nonpolar solvent is cyclohexane.

Preferably, the nitrate-passivated CsPbI of the invention₃The perovskite nanocrystal has an average particle size of 20 nm.

Compared with the prior art, the embodiment of the invention has the following beneficial effects:

1. the invention provides a synthesis method of nitrate-passivated red CsPbI3 perovskite nanocrystalline, which is simple to operate and low in energy consumption;

2. the red CsPbI3 perovskite nanocrystalline prepared by the method has the advantages of stable sample phase, uniform appearance size, narrow half-peak width, high luminescent color purity, few surface defects and high quantum efficiency, and can be used in the fields of solar cells, photoelectric detectors, light-emitting diodes and the like.

Drawings

FIG. 1 shows CsPbI prepared according to an embodiment of the present invention₃TEM images of perovskites.

FIG. 2 shows CsPbI prepared according to an embodiment of the present invention₃XRD pattern of perovskite.

FIG. 3 shows CsPbI prepared according to an embodiment of the present invention₃Photoluminescence (PL) spectrum of perovskite.

FIG. 4 shows CsPbI prepared according to an embodiment of the present invention₃Quantum efficiency (PLQY) profile of perovskite.

FIG. 5 shows CsPbI in an embodiment of the present invention₃Stability profile of nanocrystals.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The invention has the substantial innovation points that: the method comprises the steps of adopting an improved thermal injection method, fully dissolving lead iodide and nitrate in an octadecene solvent mixed with surfactants oleic acid and oleylamine under the protection of inert gas, enabling Pb atoms and I atoms to be fully contacted with the surfactants, calcium ions and nitrate ions, injecting a precursor Cs source after reacting for a period of time at a certain temperature, and then gradually nucleating the Cs source with lead iodide and nitrate solution in the process, and controlling CsPbI by adjusting the amount of the nitrate₃The perovskite has the appearance and the crystalline phase, so that the regulation and control of the luminescence peak position and the fluorescence quantum efficiency are realized, and the prepared sample has excellent room temperature stability.

Specific implementations of the present invention are described in detail below with reference to specific embodiments.

In the first embodiment, referring to fig. 1-5, the calcium nitrate passivated high-efficiency stable cubic phase CsPbI provided by the embodiments of the present invention₃The nanocrystalline and the preparation method thereof comprise the following steps:

step 1: 10mL of octadecene, 1mL of oleic acid and 0.4g of cesium carbonate were added to a 50mL three-necked flask under N₂Heating to 120 ℃ in the atmosphere, stirring the solution until the solution is dissolved and becomes light yellow, and obtaining a precursor solution for later experiment;

step 2: 0.3mmol of lead iodide, 2mL of oleic acid, 2mL of oleylamine and 0.08mmol of Ca (NO)₃)₂Adding into a three-necked flask containing 10mL of octadecene, evacuating for 30min, and introducing inert gas N₂Heating to 120 deg.C and stirring for 40min to obtain clear and transparent solution;

and step 3: heating to 170 ℃, and injecting 1mL of precursor into the transparent solution in the step 2;

and 4, step 4: kept at 170 ℃ for 20 seconds and rapidly cooled to room temperature with an ice-water bath, and then the mixed solution in step 3 was centrifugally dispersed into 2mL of cyclohexane to obtain CsPbI₃And (4) nanocrystals.

Example two, referring to fig. 1-4, the same process as in example 1 is used, except that Ca (NO) in step 2 of example 1 is used₃)₂The amount of (2) was changed to 0.16mmol, and the other conditions were kept constant.

EXAMPLE III referring to FIGS. 1-4, the same procedure as in example 1 is followed, except that Ca (NO) in step 2 of example 1 is used₃)₂The amount of (2) was changed to 0.3mmol, and the other conditions were kept constant.

Example four, referring to fig. 1 to 4, the same process as in example 1 was used except that the temperature of the heat injection in step 2 of example 1 was changed to 160 ℃, and the other conditions were kept the same.

Example five, referring to fig. 1 to 4, the same process as in example 2 was used except that the temperature of the heat injection in step 2 of example 1 was changed to 165 deg.c, and the other conditions were kept the same.

Example six, referring to fig. 1 to 4, the same process as in example 2 was used except that the temperature of the heat injection in step 2 of example 1 was changed to 175 ℃, and the other conditions were kept the same.

As can be seen by adjusting the amount of calcium nitrate added, a certain amount of calcium nitrate can promote efficient and stable cubic phase CsPbI₃Formation of nanocrystals, but too little to obtain a stable cubic phase CsPbI₃(ii) a As can be seen from a-c in FIG. 1, with respect to the addition of 0.08mmol Ca (NO)₃)₂And 0.16mmolCa (NO)₃)₂0.3mmol of Ca (NO) was added₃)₂The nanocrystals obtained were of uniform polyhedral morphology (figure 1) and were also experimentally demonstrated by the addition of 0.3mmol of Ca (NO)₃)₂The obtained nanocrystal is in a cubic phase (figure 2), an emission peak generates obvious blue shift (figure 3), the defects are fewer, the quantum efficiency is higher (figure 4), and the stability is prolonged from the initial 30 days to 270 days.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.