Large Stokes shift perovskite nanocrystal based on disodium guanylate and preparation method and application thereof

Abstract

The invention belongs to the technical field of photoelectric materials, and particularly relates to a large Stokes shift perovskite nanocrystal based on disodium guanylate as well as a preparation method and application of the large Stokes shift perovskite nanocrystal. The preparation method of the perovskite nanocrystal comprises the following steps: mixing a lead source and a cesium source, carrying out first-time ball milling, and after the first-time ball milling is finished, adding disodium guanylate, and carrying out second-time ball milling, so as to obtain the large-Stokes shift perovskite nanocrystal based on disodium guanylate. And the obtained perovskite nanocrystal has relatively large Stokes displacement and is suitable for being applied to photoelectric devices.

Description

Technical Field

[0001] The invention belongs to the technical field of optoelectronic materials, and in particular relates to a large Stokes shift perovskite nanocrystal based on disodium guanylate and a preparation method and application thereof. Background Art

[0002] Metal halide perovskites have the advantages of high brightness, high defect tolerance, tunable emission wavelength, high color purity and high fluorescence quantum yield (PLQY), and show great application potential in photovoltaic power generation and optoelectronic devices. However, as a "star material" that researchers pay great attention to, it has been criticized for its poor stability.

[0003] Disodium guanylate (FCC), chemical formula is C 10 H 12 N 5 O 8 P·Na 2 . Disodium guanylate is a common food additive at home and abroad. It is non-toxic and inexpensive. From the perspective of economic applicability, it is a green and cheap ligand molecule. Stokes shift is one of the important parameters for evaluating the photophysical properties of perovskite nanocrystals. If the Stokes shift of the perovskite nanocrystal itself is relatively small, then during the fluorescence emission process, reabsorption is likely to occur, causing fluorescence self-quenching, thereby reducing the utilization efficiency of the material. Therefore, the rational design and synthesis of perovskite nanocrystals with large Stokes shifts is of great research significance. Summary of the invention

[0004] One of the purposes of the present invention is to provide a method for preparing large Stokes shift perovskite nanocrystals based on disodium guanylate, and the preparation process is simple.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing large Stokes shift perovskite nanocrystals based on disodium guanylate comprises the following steps:

[0007] The lead source and the cesium source are mixed and ball-milled for the first time. After the first ball-milling, disodium guanylate is added and ball-milled for the second time to obtain large Stokes shift perovskite nanocrystals based on disodium guanylate.

[0008] Furthermore, the molar ratio of the lead source, the cesium source and the disodium guanylate is 1:1:(0.25-0.5).

[0009] The guanylate disodium molecule itself contains multiple functional groups such as ether oxygen groups, phosphorus oxygen groups and amino groups. The electrostatic potential around the oxygen atoms on the ether oxygen groups and the phosphorus atoms on the phosphorus oxygen groups is negative, and there is a strong interaction between them and the positively charged particles. For the cesium lead bromine system perovskite nanocrystal, the Cs at the A position + and Pb at position B 2+ All of them may produce electrostatic interactions with disodium guanylate, thereby passivating the vacancy defects at the A and B sites, and then preparing high-performance perovskite nanocrystals. The electrostatic potential diagram of disodium guanylate can be found in Figure 1 .

[0010] Furthermore, the lead source is selected from one of lead bromide, lead chloride and lead iodide; the cesium source is selected from one of cesium bromide, cesium chloride and cesium iodide.

[0011] Furthermore, the ball-to-material ratio of the first ball milling is 1:(2-3).

[0012] Furthermore, the rotation speeds of the first ball milling and the second ball milling are both 1100-1500 rpm, and the ball milling time is both 25-40 min.

[0013] Furthermore, the ball milling medium is zirconium oxide.

[0014] The second object of the present invention is to provide a large Stokes shift perovskite nanocrystal based on disodium guanylate, which has a larger Stokes shift.

[0015] To achieve the above object, the present invention adopts the following technical solutions:

[0016] A large Stokes shift perovskite nanocrystal based on disodium guanylate is prepared by the above-mentioned preparation method.

[0017] The third object of the present invention is to provide an application of large Stokes shift perovskite nanocrystals based on disodium guanylate, which has broad application prospects.

[0018] To achieve the above object, the present invention adopts the following technical solutions:

[0019] The application of the large Stokes shift perovskite nanocrystals based on disodium guanylate in the field of optoelectronic devices.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The present invention uses disodium guanylate as a ligand for the first time to prepare perovskite nanocrystals. The disodium guanylate molecule itself contains multiple functional groups such as ether oxygen groups, phosphorus oxygen groups and amino groups. The electrostatic potential around the oxygen atoms on the ether oxygen groups and the phosphorus atoms on the phosphorus oxygen groups is negative, and there is a strong interaction between them and the positively charged particles. For the cesium lead bromine system perovskite nanocrystals, Cs at the A position + and Pb at position B 2+ They may all produce electrostatic interactions with disodium guanylate, thereby passivating the vacancy defects at the A and B sites, and thus preparing high-performance perovskite nanocrystals.

[0022] (2) The preparation method provided by the present invention has a simple process, does not use additional solvents, and does not require a high-temperature crystal growth process, and is suitable for industrial production.

[0023] (3) The perovskite nanocrystals obtained by the present invention can achieve an ultra-high absolute fluorescence quantum yield of 95.89% and have a large Stokes shift. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the electrostatic potential diagram of disodium guanylate;

[0025] Figure 2 are optical pictures of the perovskite nanocrystalline powder obtained in Example 1 under different light sources;

[0026] Figure 3 is the XRD spectrum of the perovskite nanocrystal obtained in Example 1;

[0027] Figure 4 is a graph showing the absolute fluorescence quantum yield of perovskite nanocrystals obtained in Example 1;

[0028] Figure 5 This is a graph showing the absolute fluorescence quantum yield of perovskite nanocrystals obtained in Comparative Example 1;

[0029] Figure 6 is the UV-visible absorption spectrum of the perovskite nanocrystal obtained in Example 1;

[0030] Figure 7 is a photoemission spectrum of the perovskite nanocrystal obtained in Example 1;

[0031] Figure 8 is the UV-visible absorption spectrum of the perovskite nanocrystal obtained in Comparative Example 1;

[0032] Fig. 9 This is the photoemission spectrum of the perovskite nanocrystals obtained in Comparative Example 1. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further explained below in conjunction with specific embodiments, comparative examples, test examples and drawings.

[0034] In the following examples, comparative examples and test examples, the raw materials and preparation methods used are conventional materials and techniques in the art unless otherwise specified.

[0035] Among them, some of the reagents involved and their purchase sources are shown in Table 1.

[0036] Table 1

[0037]

[0038] 1. Embodiment

[0039] Example 1

[0040] Example 1 provides a method for preparing large Stokes shift perovskite nanocrystals based on disodium guanylate, and the specific preparation process is as follows:

[0041] According to the molar ratio of lead bromide, cesium bromide and disodium guanylate of 1:1:0.4, lead bromide and cesium bromide are placed in a ball mill and mixed, zirconium oxide balls (ball-to-material ratio is 1:2.5) are added, and ball milling is carried out at a speed of 1200 rpm for 30 minutes; after the first ball milling, disodium guanylate is added and ball milling is carried out at a speed of 1200 rpm for 30 minutes to obtain large Stokes shift perovskite nanocrystals based on disodium guanylate.

[0042] Example 1 also provides a large Stokes shift perovskite nanocrystal based on disodium guanylate, which is prepared using the above preparation method.

[0043] Example 2

[0044] Example 2 provides a method for preparing large Stokes shift perovskite nanocrystals based on disodium guanylate, and the specific preparation process is as follows:

[0045] According to the molar ratio of lead chloride, cesium chloride and disodium guanylate of 1:1:0.25, lead chloride and cesium chloride are placed in a ball mill and mixed, zirconium oxide balls (ball-to-material ratio is 1:2) are added, and ball milling is performed at a speed of 1100 rpm for 40 minutes; after the first ball milling, disodium guanylate is added and ball milling is performed at a speed of 1100 rpm for 40 minutes to obtain large Stokes shift perovskite nanocrystals based on disodium guanylate.

[0046] Example 2 also provides a large Stokes shift perovskite nanocrystal based on disodium guanylate, which is prepared using the above preparation method.

[0047] Example 3

[0048] Example 3 provides a method for preparing large Stokes shift perovskite nanocrystals based on disodium guanylate, and the specific preparation process is as follows:

[0049] According to the molar ratio of lead iodide, cesium iodide and disodium guanylate of 1:1:0.5, lead iodide and cesium iodide are placed in a ball mill and mixed, zirconium oxide balls (ball-to-material ratio is 1:3) are added, and ball milling is performed at a speed of 1500 rpm for 25 minutes; after the first ball milling, disodium guanylate is added and ball milling is performed at a speed of 1500 rpm for 25 minutes to obtain large Stokes shift perovskite nanocrystals based on disodium guanylate.

[0050] Example 3 also provides a large Stokes shift perovskite nanocrystal based on disodium guanylate, which is prepared using the above preparation method.

[0051] 2. Comparative Example

[0052] Comparative Example 1

[0053] Comparative Example 1 uses oleic acid and oleylamine as ligands and prepares perovskite nanocrystals according to conventional methods.

[0054] 3. Test examples

[0055] Test Example 1

[0056] The perovskite nanocrystals obtained in Example 1 were observed under ultraviolet light (365nm) and sunlight. The results are shown in Figure 2 shown.

[0057] Figure 2 These are optical images of the perovskite nanocrystalline powder obtained in Example 1 under different light sources. Figure 2 a is a picture of the perovskite nanocrystal powder obtained in Example 1 under sunlight, Figure 2 b is a picture of the perovskite nanocrystal powder obtained in Example 1 under ultraviolet light. Figure 2 It can be seen that the powder after ball milling is colorless under sunlight, but has obvious green fluorescence emission under ultraviolet light.

[0058] Test Example 2

[0059] The perovskite nanocrystals obtained in Example 1 were tested using an X-ray diffraction (XRD) analyzer. Figure 3 shown.

[0060] Figure 3 This is the XRD pattern of the perovskite nanocrystal obtained in Example 1. Figure 3 It can be seen that the prepared perovskite nanocrystalline powder and Cs 4 PbB 6The nanocrystal phase corresponds to the Cs nanocrystal phase, with obvious characteristic peaks and no obvious angle shift. Therefore, the prepared perovskite nanocrystal is Cs 4 PbB 6 Perovskite nanocrystals.

[0061] Test Example 3

[0062] The perovskite nanocrystals obtained in Example 1 and Comparative Example 1 were dispersed in chlorobenzene solution to prepare 0.1 mg / mL solutions. 2 mL of each solution was placed in a quartz four-way cuvette. The absolute fluorescence quantum yield was tested using the FLS 980 quantum yield module produced in Edinburgh. The excitation light source was set to a xenon lamp with a wavelength of 250 nm. The test results are shown in Figure 4-5 shown.

[0063] Figure 4 This is a graph showing the absolute fluorescence quantum yield of the perovskite nanocrystals obtained in Example 1. Figure 5 This is the absolute fluorescence quantum yield result of the perovskite nanocrystal obtained in Example 1. Figure 4-5 It can be seen that the absolute fluorescence quantum yield of the perovskite nanocrystals obtained in Example 1 is 95.89%, and the absolute fluorescence quantum yield of the perovskite nanocrystals obtained in Comparative Example 1 is only 33.16%. As can be seen from the above, the absolute fluorescence quantum yield of the perovskite nanocrystals obtained by using disodium guanylate as a ligand in the present invention is significantly improved compared with the perovskite nanocrystals obtained by using oleylamine as a ligand.

[0064] Test Example 4

[0065] The perovskite nanocrystals obtained in Example 1 and Comparative Example 1 were dispersed in chlorobenzene solution to prepare 0.1 mg / mL solutions. 2 mL of each solution was added to a quartz double-pass cuvette, and a medium-speed scan was performed in the wavelength range of 300-800 nm to perform UV-visible absorption spectrum testing. When the sample test was performed, the influence of background solvents etc. needed to be removed. 2 mL of pure chlorobenzene solvent was added to the double-pass cuvette for blank baseline scanning. The test results are shown in Figure 6-9 .

[0066] Figure 6-7 They are respectively the UV-visible absorption spectrum and the photoemission spectrum of the perovskite nanocrystals obtained in Example 1. Figure 8-9 The UV-visible absorption spectrum and photoemission spectrum of the perovskite nanocrystal obtained in Example 1 are shown in Table 1. Figure 6 It can be seen that the perovskite nanocrystals obtained in Example 1 have two obvious absorption peaks at 330nm and 365nm, and then the absorption peak intensity decreases significantly and remains below 10% at 520nm. Figure 7 It can be seen that the fluorescence emission peak position of the perovskite nanocrystal obtained in Example 1 is about 520nm. Figure 6 and Figure 7It can be seen that the perovskite nanocrystals obtained in Example 1 effectively reduce the reabsorption effect of photons.

[0067] Depend on Figure 8 It can be seen that the perovskite nanocrystals obtained in Comparative Example 1 have an obvious absorption peak at 330nm, and then the absorption peak intensity begins to decrease, but still remains above 20% at 520nm. Fig. 9 It can be seen that the fluorescence emission peak position of the perovskite nanocrystal obtained in Comparative Example 1 is about 520nm. Figure 8 and Fig. 9 It can be seen that the perovskite nanocrystals obtained in Comparative Example 1 still have a large photon reabsorption effect.

[0068] In summary, by comparing and analyzing the UV-visible absorption spectra and photoemission spectra of the perovskite nanocrystals obtained in Example 1 and Comparative Example 1, it can be seen that the perovskite nanocrystals obtained in Example 1 have a larger Stokes shift, so the photon reabsorption effect is lower, and thus more suitable for application in optoelectronic devices.

[0069] The above are only preferred embodiments of the present invention, and are not limited to the above examples. For those skilled in the art, various changes and variations are possible under the principle of the present invention. Any modifications and improvements made should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing large Stokes shift perovskite nanocrystals based on disodium guanylate, characterized in that: The following steps are involved: The lead source and the cesium source are mixed and ball-milled for the first time. After the first ball-milling, disodium guanylate is added and ball-milled for the second time to obtain large Stokes shift perovskite nanocrystals based on disodium guanylate.

2. The method for preparing large Stokes shift perovskite nanocrystals based on disodium guanylate as claimed in claim 1, characterized in that: The molar ratio of the lead source, the cesium source and disodium guanylate is 1:1:(0.25-0.5).

3. The method for preparing large Stokes shift perovskite nanocrystals based on disodium guanylate as claimed in claim 1, characterized in that: The lead source is selected from one of lead bromide, lead chloride and lead iodide; the cesium source is selected from one of cesium bromide, cesium chloride and cesium iodide.

4. The method for preparing large Stokes shift perovskite nanocrystals based on disodium guanylate as claimed in claim 1, characterized in that: The ball-to-material ratio of the first ball milling is 1:(2-3).

5. The method for preparing large Stokes shift perovskite nanocrystals based on disodium guanylate as claimed in claim 1, characterized in that: The rotation speeds of the first ball milling and the second ball milling are both 1100-1500 rpm, and the ball milling time is both 25-40 min.

6. The method for preparing large Stokes shift perovskite nanocrystals based on disodium guanylate as claimed in claim 1, characterized in that: The medium of the ball mill is zirconium oxide.

7. A large Stokes shift perovskite nanocrystal based on disodium guanylate, characterized in that: The preparation method is described in any one of claims 1 to 6.

8. The use of large Stokes shift perovskite nanocrystals based on disodium guanylate as claimed in claim 7, characterized in that: Application in the field of optoelectronic devices.

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