KR102017797B1 - CsPbBr3/PbSe Nano Composite Synthesis - Google Patents

Abstract

The invention CsPbBr ₃ / PbSe nanocomposites and to a method for synthesizing them, the complex according to the invention by having a structure in which the PbSe components outside of CsPbBr ₃ quantum dot distribution, CsPbBr ₃ quantum dots are covered by the PbSe long The crystal structure of CsPbBr ₃ is maintained even after the time heating process, and there is an advantage of improving stability by protecting the perovskite material from self-expansion during the reaction of the optoelectronic device including the composite.

Description

CsPbBr3 / PbSe Nano Composite Synthesis

The present invention relates to a CsPbBr ₃ / PbSe nanocomposite and a method for synthesizing it.

Recently, much research on halogenated perovskite has focused on a new generation of solar cells, light emitting diodes, transistors, lasers and memristors in the form of thin films, nanowires and nanorods. The power conversion efficiency of halogenated perovskite-based thin-film solar cells rapidly increased from 3.8% to more than 20% in 10 years. Cesium lead halogen compounds in organic and inorganic perovskite materials showed better stability than organic perovskite materials, suggesting great potential for optoelectronic devices. Studies of the morphology of perovskite show that nano-sized materials exhibit superior properties, such as higher quantum efficiency, narrower width of emission, and color variability compared to bulk-sized materials. Recently, cesium lead halide quantum dots are expected to have high purity for light emitting diodes. It has also been found that the growth rate, clarity and size of CsPbBr ₃ can be effectively controlled by varying the length of the carbon chains of the acids and amines in the ligand during synthesis. This shows the possibility of finding the best structure and size for cesium lead halide quantum dots. However, the thermal and electrical stability of cesium lead halide quantum dots is still limited.

Korea Patent Registration 10-1465360.

It is an object of the present invention to provide a composite having improved thermal and electrical stability of cesium lead halide quantum dots.

In order to solve the said subject, this invention is a 1st crystalline component; And a second crystalline component, wherein the first crystalline component is located at the center, and the second crystalline component is a structure formed by being dispersed in the outer portion of the first crystalline component, wherein the first crystalline component satisfies the following composition 1 In addition, the second crystalline component provides a composite that satisfies the following composition 2.

[Composition 1]

CsM ¹ X ₃

In composition 1, M ¹ is Pb or Sn, X is Br, Cl or I,

[Composition 2]

M ² Se

In composition 2, M ² is Pb or Sn.

Complex according to the invention by having the two PbSe component distribution structure on the outside of CsPbBr ₃ quantum dots, CsPbBr ₃ quantum dots are covered by the PbSe, and the crystal structure of CsPbBr ₃ remain after the step of heating time, comprising the complex There is an advantage of protecting the perovskite material from magnetic expansion during the reaction of the optoelectronic device.

1 is a schematic diagram schematically showing the structure of a CsPbBr ₃ / PbSe complex according to the present invention.
Figure 2 is a photograph taken of the CsPbBr ₃ / PbSe complex in the hexane solution in the normal light (AC) and UV lamp (DF), Examples 1-1, 2- from the left of the three solutions in A and D, respectively 1 and 3-1 is a photograph of the composite prepared according to Figures B and E from the left is a photograph of the composite prepared according to Examples 1-2, 2-2 and 3-2, C and F is carried out from the left Photos of the composites prepared according to Examples 1-3, 2-3 and 3-3.
3 is a UV-Vis absorption spectrum measurement results of the CsPbBr ₃ quantum dot according to the preparation example and the CsPbBr ₃ / PbSe complex according to Examples 1-3, 2-3 and 3-3.
4 shows the results of PL spectra of CsPbBr ₃ quantum dots according to the preparation example and CsPbBr ₃ / PbSe complexes according to Examples 1-3, 2-3, and 3-3.
5 is an XRD pattern of CsPbBr ₃ quantum dots according to the preparation example and CsPbBr ₃ / PbSe complexes according to Examples 1-3, 2-3, and 3-3.
6 shows the results of SRPES spectrum measurement of CsPbBr ₃ quantum dots according to the preparation example and CsPbBr ₃ / PbSe complexes according to Examples 1-3, 2-3 and 3-3, where a is Examples 1-3 and b is carried out. Examples 2-3 and c are the results of Example 3-3.
7 is a FE-SEM photograph of the CsPbBr ₃ quantum dot according to the preparation example and the CsPbBr ₃ / PbSe complex according to Example 1-3, a is a quantum dot according to a comparative example, b is a complex according to Examples 1-3. .
8 is a TEM image of a CsPbBr ₃ / PbSe complex according to Examples 1-3.

As the invention allows for various changes and numerous embodiments, particular embodiments will be illustrated in the drawings and described in detail in the written description.

However, this is not intended to limit the present invention to specific embodiments, it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the present invention. In the following description of the present invention, if it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

Terms such as first and second may be used to describe various components, but the components should not be limited by the terms. The terms are only used to distinguish one component from another.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.

In the present invention, the terms "comprises" or "having" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Therefore, the configurations shown in the embodiments described herein are only one of the most preferred embodiments of the present invention and do not represent all of the technical idea of the present invention, and various equivalents may be substituted for them at the time of the present application. And variations.

In addition, it is to be understood that the accompanying drawings in the present invention are shown to be enlarged or reduced for convenience of description.

The present invention relates to a nanocomposite for increasing the efficiency of the optoelectronic device to provide a composite that can protect the perovskite from magnetic expansion by preventing the size of the perovskite from expanding at high temperatures during the reaction of the optoelectronic device. .

Hereinafter, the composite according to the present invention will be described in detail.

The complex according to the present invention comprises a first crystalline component; And a second crystalline component, wherein the first crystalline component is located at the center, and the second crystalline component is a structure formed by being dispersed in the outer portion of the first crystalline component, wherein the first crystalline component satisfies the following composition 1 In addition, the second crystalline component satisfies the following composition 2.

[Composition 1]

CsM ¹ X ₃

In composition 1, M ¹ is Pb or Sn, X is Br, Cl or I,

[Composition 2]

M ² Se

In composition 2, M ² is Pb or Sn.

Specifically, in the composition 1 M ¹ may be Pb, X may be Br. In addition, in the composition 2, M ² may be Pb.

As one example, in the composite of the present invention, the first crystalline component may have a CsPbBr ₃ composition, and the second crystalline component may have a PbSe composition.

The complex is CsPbBr _{3 as} the first crystalline component Is centrally located, The second position by the outer frame section to the PbSe crystal form component, is also protected by the PbSe crystal structure of CsPbBr ₃ by performing a long heating process has the advantage of improving the stability of the quantum dots CsPbBr _3. Therefore, the optoelectronic device using the composite according to the present invention has an effect of preventing the size of the perovskite from expanding at a high temperature during the reaction.

The molar ratio of Cs and Se contained in the complex may range from 0.5: 1 to 1: 4. Specifically, the molar ratio of Cs and Se may be 0.6: 1 to 1: 3.5, 1.7: 1 to 1: 3, or 1: 1 to 1: 3. When the molar ratio of Cs and Se contained in the composite is within the above range, the photoluminescence (PL) spectrum is maintained at a high level for a long time, thereby improving the stability of the CsPbBr ₃ quantum dot.

As one example, the molar ratio of Cs and Se contained in the composite ranges from 0.6: 1 to 1: 1.3, and has a peak in the 470-485 nm wavelength region and the 510-520 nm wavelength region, respectively, when the PL spectrum is measured for the composite. Can be. Specifically, the molar ratio of Cs and Se contained in the complex is 0.7: 1 to 1: 1.2 or 1: 1, and when the PL spectrum of the composite is measured, each of the peaks may have a peak in the 475-480 nm wavelength region and the 513-518 nm wavelength region. Can be. This indicates that when the molar ratio of Cs and Se contained in the complex is 1: 1, cyan consists of a blue peak of about 478 nm and a green peak of about 516 nm (see Experimental Example 3).

As another example, the molar ratio of Cs and Se contained in the composite ranges from 1: 1.6 to 1: 2.4, and may have a peak in the wavelength region of 470 to 485 nm when measured by PL spectrum. Specifically, the molar ratio of Cs and Se is 1: 1.7 to 1: 2.3, 1: 1.8 to 1: 2.1 or 1: 2, and may have a peak in the wavelength range of 475 to 480 nm when measuring the PL spectrum. This indicates that cyan is composed of a blue peak of about 478 nm when the molar ratio of Cs and Se contained in the complex is in the range of about 1: 2 (see Experimental Example 3).

As another example, the molar ratio of Cs and Se contained in the composite may range from 1: 2.6 to 1: 3.4, and may have peaks in the wavelength region of 458 to 466 nm when measured by PL spectrum. Specifically, the molar ratio of Cs and Se is 1: 2.7 to 1: 3.3, 1:28 to 1: 3.2 or 1: 3, and may have a peak in the wavelength range of 460 to 464 nm when measuring the PL spectrum. This indicates that when the molar ratio of Cs and Se contained in the complex is in the range of about 1: 3, cyan consists of a blue peak of about 462 nm (see Experimental Example 3).

The average diameter of the composite can range from 11 to 15 nm. Specifically, the average diameter of the composite may be 11.5 to 14.5 nm, 12 to 14 nm or 12 to 13 nm.

As an example, in the synthesis of the composite according to the invention, the prepared CsPbBr ₃ When the PbSe synthesis is performed on the quantum dots, the synthesis temperature may be 130 to 210 ° C. Specifically, the synthesis temperature may be 140 to 200 ° C, or 150 to 190 ° C. CsPbBr ₃ when the composite synthesis is carried out at a temperature in the above range PbSe components may be well formed outside the quantum dots.

Hereinafter, the present invention will be described in more detail with reference to examples according to the present invention, but the scope of the present invention is not limited to the following examples.

Production Example : CsPbBr ₃ Quantum dots  synthesis

70 mg of PbBr ₃ was placed in a 100 ml flask with 10 ml of octadecane (ODE), 1 ml of oleic acid (OA) and 0.5 ml of oleylamine (OAm). With was then completely dispersed PbBr ₃ by heating the mixture to 120 ℃ under N ₂ for ₃ CsCO 0.814g octane and decane (ODE) 30ml and oleic acid (OA) in 2.5ml into 100ml flask cesium oleate (Cesium oleate) was prepared. Then, the mixture was prepared by heating the PbBr ₃ solution to 190 ° C. and then injecting 0.4 ml of cesium oleate heated to 100 ° C. The mixture was then cooled in iced water to give CsPbBr ₃ CdPbBr ₃ was precipitated by quantum dots and washed with a 1: 1 solution of hexane and butanol by volume. Quantum dots were prepared. Then prepared CsPbBr ₃ Quantum dots were used by dispersing in toluene.

Example  1-1: by Cs and Se Molar  Preparation of 1: 1 composite (synthesis temperature 150 ° C)

The source of selenium was prepared by loading 10 mg of selenium in 0.5 ml of trioctylphosphine (TOP) and 0.5 ml of octadecane (ODE). TOPSe was prepared by heating the mixture to 140 ° C. over 1 h. Then 0.2 ml of the TOPSe CsPbBr ₃ prepared by Preparation Example 1 Quantum dots were quickly added to the dispersed solution and maintained at a synthesis temperature of 150 ° C. for 1 hour. Then the color of the solution changed from light green to dark green. The material was precipitated and washed with hexane and 2-butanol to prepare CsPbBr ₃ / PbSe complex. The synthesized complex was redispersed in toluene for later use.

Example  1-2: of Cs and Se Molar  Preparation of 1: 1 composite (synthetic temperature 170 ° C)

A CsPbBr ₃ / PbSe composite was prepared in the same manner as in Example 1-1 except that the synthesis temperature was maintained at 170 ° C.

Example  1-3: Cs and Se Molar  Preparation of 1: 1 composite (synthesis temperature 190 ° C)

A CsPbBr ₃ / PbSe composite was prepared in the same manner as in Example 1-1 except that the synthesis temperature was maintained at 190 ° C.

Example  2-1: by Cs and Se Molar  Preparation of 1: 2 composite (synthesis temperature 150 ° C)

CsPbBr ₃ / PbSe complex was prepared in the same manner as in Example 1-1 except that 0.4 ml of TOPSe was added to adjust the molar ratio of Cs and Se to 1: 2.

Example  2-2: by Cs and Se Molar  Preparation of 1: 2 composite (synthetic temperature 170 ° C.)

A CsPbBr ₃ / PbSe composite was prepared in the same manner as in Example 2-1 except that the synthesis temperature was maintained at 170 ° C.

Example  2-3: Cs and Se Molar  Preparation of 1: 2 composite (synthetic temperature 190 ° C)

A CsPbBr ₃ / PbSe composite was prepared in the same manner as in Example 2-1 except that the synthesis temperature was maintained at 190 ° C.

Example  3-1: by Cs and Se Molar  Preparation of 1: 3 composite (synthetic temperature 150 ° C.)

CsPbBr ₃ / PbSe complex was prepared in the same manner as in Example 1-1 except that 0.6 ml of TOPSe was added to adjust the molar ratio of Cs and Se to 1: 3.

Example  3-2: by Cs and Se Molar  Preparation of 1: 1 composite (synthetic temperature 170 ° C)

A CsPbBr ₃ / PbSe composite was prepared in the same manner as in Example 3-1, except that the synthesis temperature was maintained at 170 ° C.

Example  3-3: by Cs and Se Molar  Preparation of 1: 1 composite (synthesis temperature 190 ° C)

A CsPbBr ₃ / PbSe composite was prepared in the same manner as in Example 3-1, except that the synthesis temperature was maintained at 190 ° C.

1 is a schematic diagram showing the structure of a CsPbBr ₃ / PbSe composite prepared according to an embodiment of the present invention. 1, it can be seen that the PbSe component is located outside the CsPbBr ₃ quantum dot.

Comparative example

As a comparative example, CsPbBr ₃ quantum dots, in which no PbSe component was formed in the outer periphery prepared according to the preparation example, were used.

Experimental Example  1: Observation of the emission light of the complex

After dispersing the composite prepared in Examples 1-1 to 3-3 in the hexane solution, the composite solution was photographed under normal light and UV lamp. At this time, the wavelength of the UV lamp was 365nm. The results are shown in Figure 2, in Figure 2 A to C is a picture taken in the normal light, D to F is a picture taken in the UV lamp, Example 1 from the left of the three solutions in each of A and D -1, 2-1 and 3-1 is a photograph of the composite prepared according to Figures B and E are photographs of the composite prepared according to Examples 1-2, 2-2 and 3-2 from the left, C and F is a photograph of the composite prepared according to Examples 1-3, 2-3 and 3-3 from the left.

2, the color of the composite solution synthesized at 150 ° C. is all blue under the UV lamp, and at 170 ° C., the solution emits cyan light as the synthesis temperature increases under the UV lamp. Shifted to In the same tendency, the composite synthesized at 190 ° C emits green light under the UV lamp and the color of the emitted light changes from green to cyan as the Se concentration increases.

These results show that the emission wavelength of the CsPbBr ₃ / PbSe composite under UV lamp is longer with increasing synthesis temperature. In addition, Se increase of CsPbBr ₃ / PbSe shortened the wavelength of emitted light under UV lamp. In the present invention, the process of heating the solution of CsPbBr ₃ quantum dots for 1 hour after adding TOPSe to make the CsPbBr ₃ / PbSe complex was performed, but it was found that luminescence was detected in the UV lamp, and thus the crystal structure of CsPbBr ₃ was longer. It is maintained after the time heating process and means that CsPbBr ₃ is protected by PbSe.

Experimental Example  2: UV- Vis  Spectral measurement

UV-Vis spectra of the composites prepared in Examples 1-3, 2-3, and 3-3 and quantum dots according to Comparative Examples were measured. The measuring instrument was a UV-vis spectrophotometer. The results are shown in Figure 3, CsPbBr ₃ / PbSe 1: 1 is a complex according to Example 1-3, CsPbBr ₃ / PbSe 1: 2 is a complex according to Example 2-3, CsPbBr ₃ / PbSe 1: 3 Is the result of the composite according to Example 3-3, CsPbBr ₃ is the result of the quantum dot according to the comparative example. As the ratio of Cs and Se increased from 1: 1 to 1: 3, the absorption peak shifted and the band gap increased from about 2.42 eV to 2.48 eV. This result shows that the electronic structure of CsPbBr ₃ can be modified. Indicates.

Experimental Example  3: PL  Spectral measurement

PL spectra of the composites prepared in Examples 1-3, 2-3, and 3-3 and quantum dots according to Comparative Examples were measured. The PL spectral instrument was a JASCO V-670 UV-vis spectrophotometer and a 500W arc xenon lamp-detector (PMT-1527 Hamamatsu photomultiplier tube). The results are shown in Figure 4, CsPbBr ₃ / PbSe 1: 1 is a complex according to Example 1-3, CsPbBr ₃ / PbSe 1: 2 is a complex according to Example 2-3, CsPbBr ₃ / PbSe 1: 3 Is the result of the composite according to Example 3-3, CsPbBr ₃ is the result of the quantum dot according to the comparative example. 4, the CsPbBr3 quantum dots emit green light having a wavelength of 500-550 nm, and in the composite according to Examples 1-3, the cyan color was composed of a blue peak of 478 nm and a green peak of 516 nm. As the ratio increases from 1: 1 to 1: 3, the PL peak is shifted to 462 nm. These results confirmed that the emission color of the perovskite quantum dot can be changed from green to blue by adjusting the Cs and Se ratio of the composite material.

Experimental Example  4: XRD  Pattern measurement

The XRD patterns of the composites prepared in Examples 1-3, 2-3, and 3-3 and the quantum dots according to the comparative example were measured. The results are shown in FIG. 5, and CsPbBr ₃ / PbSe 1: 1 was used. Complex according to 1-3, CsPbBr ₃ / PbSe 1: 2 is the complex according to Example 2-3, CsPbBr ₃ / PbSe 1: 3 is the result of the complex according to Example 3-3, CsPbBr ₃ is in Comparative Example Is the result of quantum dots. Referring to FIG. 5, the CsPbBr ₃ quantum dots show two peaks at 15.16 ° and 30.6 °, and thus the synthesized CsPbBr ₃ quantum dots have a cubic structure in the (100) and (200) planes. In the CsPbBr3 / PbSe complex with a 1: 1 Cs: Se ratio, new peaks appeared at 12.8 ° and 29.1 °, corresponding to the (100) and (200) planes of Pbse. Also, CsPbBr disappear in ₃ of 100 and 200 cubic CsPbBr _three peaks, it showed a new peak at 14 ° and 16 ° to the 100 and the 101 peak of the rhombic structure of CsPbBr _3. This means that the structure of CsPbBr ₃ quantum dots changed from cubic to tetragonal by the introduction of PbSe at the surface. For the CsPbBr3 / PbSe complex with a 1: 2 Cs: Se ratio, the peaks of the PbSe (100) and (200) planes shifted to higher angles of 13 ° and 29 °. This indicates that the plane spacing of PbSe increases with increasing Se ratio. PbSe has a cubic rock salt structure with a lattice parameter of 6.12 파라미터 and CsPbBr ₃ has been reported to have a perovskite structure with a lattice parameter of 5.87 Å. Therefore, PbSe was compressed due to CsPbBr ₃ having a low lattice parameter, and the lattice parameter of PbSe was recovered with increasing Se content.

Experimental Example  5: SRPES  Spectral measurement

SRPES spectra of the complex according to Example 3-3 and the CsPbBr3 quantum dots according to the comparative example were measured. The results are shown in Figure 6, Cs 3d two peaks of the _5/2 and Cs ₃ 3d _{/ 2} is shown in the 726.1 and 740 eV. In addition, the peak of Br 3d _5/2, and Br 3d _3/2 is shown at 69.3 and 70.4eV. No peak change was observed in Cs 3d and Br 3d after PbSe was formed on the surface of CsPbBr ₃ . For 4f peak Pb, Pb 4f _7/2 and Pb 4f _5/2 corresponds to the two peaks at 138.1eV and 143eV of CsPbBr ₃ QDs showed that the. In addition, the peaks appeared at 137.5eV and 142.4eV in the CsPbBr ₃ / PbSe complex, indicating that Pb-Se bond was formed. This result shows that PbSe was well formed on the surface of CsPbBr ₃ quantum dots.

Experimental Example  6: FE- SEM  Image observation

FE-SEM images were measured to determine the size of the composite according to Example 3-3 and the CsPbBr3 quantum dots according to the comparative example. The results are shown in FIG. 7, where A is the result of the composite according to Example 3-3, and B is the result of CsPbBr ₃ quantum dots. Referring to FIG. 7, the average diameter of the CsPbBr ₃ quantum dot is about 10 nm, and the average diameter of the CsPbBr ₃ / PbSe complex is about 12 to 3 nm. This shows that PbSe adheres to the surface of CsPbBr3 to increase the size of about 2-3 nm, CsPbBr ₃ is well dispersed in the CsPbBr ₃ / PbSe complex, and CsPbBr ₃ / PbSe forms a cluster.

Experimental Example  7: TEM  Image observation

TEM images were measured to confirm the shape of the complex according to Example 3-3. As a result, referring to b of FIG. 8, the (020) plane distance of CsPbBr ₃ was measured at 0.29 nm, and the (200) plane distance of PbSe was measured at 0.30 nm, similar to the (020) plane of CsPbBr ₃ . Thus, with the surface (020) of CsPbBr ₃ it is connected to the surface 200 of the PbSe been shown to form a CsPbBr ₃ / PbSe composite.

In addition, energy distribution X-ray spectroscopy (EDS) mapping, HRTEM image and SEAD pattern analysis of Pb, Se, Br and Cs atoms confirmed that the atomic distribution of the CsPbBr ₃ / PbSe composite cluster was uniform and well formed. 8 e to h).

Claims (7)

First crystalline component; And a second crystalline component,
The first crystalline component is located in the center, the second crystalline component is a structure formed by being dispersed in the outer periphery of the first crystalline component,
The first crystalline component satisfies the composition 1 below, the second crystalline component satisfies the composition 2 below,
Complexes characterized in that the molar ratio of Cs and Se in the complex ranges from 0.5: 1 to 1: 4:
[Composition 1]
CsM ¹ X ₃
In composition 1, M ¹ is Pb or Sn, X is Br, Cl or I,
[Composition 2]
M ² Se
In composition 2, M ² is Pb or Sn.
The method of claim 1,
The first crystalline component has a CsPbBr ₃ composition,
And the second crystalline component has a PbSe composition.
delete The method of claim 1,
The molar ratio of Cs and Se in the complex ranges from 0.6: 1 to 1: 1.3,
When measuring PL spectrum,
And a peak in the 470-485 nm wavelength region and the 510-520 nm wavelength region, respectively.
The method of claim 1,
The molar ratio of Cs and Se in the complex ranges from 1: 1.6 to 1: 2.4,
When measuring PL spectrum,
Composite having a peak in the wavelength range of 470 to 485 nm.
The method of claim 1,
The molar ratio of Cs and Se in the complex ranges from 1: 2.6 to 1: 3.4,
When measuring PL spectrum,
And composites each having peaks in the wavelength region of 458-466 nm.
The method of claim 1,
The composite is characterized in that the average diameter of the complex ranges from 11 to 15 nm.

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