Large Stokes displacement perovskite nanocrystals based on disodium guanylate, their preparation methods and applications

Abstract

This invention belongs to the field of optoelectronic materials technology, specifically relating to large Stokes-displaced perovskite nanocrystals based on disodium guanylate, their preparation method, and applications. The preparation method of the perovskite nanocrystals includes the following steps: mixing a lead source and a cesium source for a first ball milling; after the first ball milling, adding disodium guanylate for a second ball milling, thus obtaining large Stokes-displaced perovskite nanocrystals based on disodium guanylate. The obtained perovskite nanocrystals exhibit a large Stokes displacement, making them suitable for application in optoelectronic devices.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic materials technology, specifically relating to large Stokes-displaced perovskite nanocrystals based on disodium guanylate, their preparation methods, and applications. Background Technology

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

[0003] Disodium guanylate (FCC), chemical formula C 10 H 12 N5O8P·Na2. Disodium guanylate is a common food additive both domestically and internationally. It is non-toxic, harmless, and inexpensive, making it a green and cost-effective 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 nanocrystals is relatively small, reabsorption during fluorescence emission can easily occur, leading to fluorescence self-quenching and reducing the material's utilization efficiency. Therefore, the rational design and synthesis of perovskite nanocrystals with larger Stokes shifts is of significant research importance. Summary of the Invention

[0004] One of the objectives of this invention is to provide a method for preparing large Stokes-displaced perovskite nanocrystals based on disodium guanylate, which has a simple preparation process.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing large Stokes-displaced perovskite nanocrystals based on disodium guanylate includes the following steps:

[0007] The lead source and cesium source were mixed and ball-milled for the first time. After the first ball milling, disodium guanylate was 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, cesium source, and disodium guanylate is 1:1:(0.25-0.5).

[0009] Sodium guanylate contains multiple functional groups, such as etheroxy groups, phosphoroxy groups, and amino groups. The electrostatic potential around the oxygen atom in the etheroxy group and the phosphorus atom in the phosphoroxy group is negative, resulting in a strong interaction with positively charged particles. For cesium-lead-bromine perovskite nanocrystals, the Cs at the A site... + And Pb at position B 2+ Both can potentially interact electrostatically with disodium guanylate, thereby passivating vacancy defects at A and B sites, leading to the fabrication of high-performance perovskite nanocrystals. See the electrostatic potential diagram of disodium guanylate for details. 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 in the first ball milling is 1:(2-3).

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

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

[0014] The second objective of this invention is to provide a large Stokes displacement perovskite nanocrystal based on disodium guanylate, which has a larger Stokes displacement.

[0015] To achieve the above objectives, the present invention adopts the following technical solution:

[0016] A large Stokes-displaced perovskite nanocrystal based on disodium guanylate was prepared using the method described above.

[0017] The third objective of this invention is to provide an application of large Stokes-displaced perovskite nanocrystals based on disodium guanylate, which has broad application prospects.

[0018] To achieve the above objectives, the present invention adopts the following technical solution:

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

[0020] Compared with the prior art, the beneficial effects of this invention are as follows:

[0021] (1) This invention is the first to use disodium guanylate as a ligand to prepare perovskite nanocrystals. The disodium guanylate molecule itself contains multiple functional groups such as etheroxy groups, phosphoroxy groups, and amino groups. The electrostatic potential around the oxygen atom on the etheroxy group and the phosphorus atom on the phosphoroxy group is negative, resulting in a strong interaction with positively charged particles. For cesium-lead-bromine perovskite nanocrystals, the Cs at the A site... + And Pb at position B 2+ Both can generate electrostatic interactions with disodium guanylate, thereby passivating vacancy defects at A and B sites, and thus preparing perovskite nanocrystals with high performance.

[0022] (2) The preparation method provided by the present invention is simple, 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 in this invention can achieve an ultra-high absolute fluorescence quantum yield of 95.89% and have a large Stokes shift. Attached Figure Description

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

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

[0026] Figure 3 The XRD pattern of the perovskite nanocrystals obtained in Example 1;

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

[0028] Figure 5 The graph shows the absolute fluorescence quantum yield of the perovskite nanocrystals obtained in Comparative Example 1.

[0029] Figure 6 This is the UV-Vis absorption spectrum of the perovskite nanocrystals obtained in Example 1;

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

[0031] Figure 8 The UV-Vis absorption spectrum of the perovskite nanocrystals obtained in Comparative Example 1 is shown below.

[0032] Figure 9 This is the photoemission spectrum of the perovskite nanocrystals obtained in Comparative Example 1. Detailed Implementation

[0033] The technical solution of the present invention will be further explained below with reference to specific embodiments, comparative examples, experimental examples and accompanying drawings.

[0034] Unless otherwise specified, the raw materials and preparation methods used in the following examples, comparative examples, and experimental cases are all conventional materials and techniques in the art.

[0035] The reagents involved and their sources of purchase are listed in Table 1.

[0036] Table 1

[0037]

[0038] 1. Example

[0039] Example 1

[0040] Example 1 provides a method for preparing large Stokes-shifted perovskite nanocrystals based on disodium guanylate. The specific preparation process is as follows:

[0041] Lead bromide, cesium bromide, and disodium guanylate were mixed in a ball mill jar at a molar ratio of 1:1:0.4. Zirconia balls (ball-to-material ratio of 1:2.5) were added, and the mixture was ball-milled at 1200 rpm for 30 min. After the first ball milling, disodium guanylate was added and ball-milled at 1200 rpm for 30 min to obtain large Stokes displacement perovskite nanocrystals based on disodium guanylate.

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

[0043] Example 2

[0044] Example 2 provides a method for preparing large Stokes-shifted perovskite nanocrystals based on disodium guanylate. The specific preparation process is as follows:

[0045] Lead chloride, cesium chloride, and disodium guanylate were mixed in a ball mill jar at a molar ratio of 1:1:0.25. Zirconia balls (ball-to-material ratio of 1:2) were added and the mixture was ball-milled at 1100 rpm for 40 min. After the first ball milling, disodium guanylate was added and the mixture was ball-milled at 1100 rpm for 40 min to obtain large Stokes shift perovskite nanocrystals based on disodium guanylate.

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

[0047] Example 3

[0048] Example 3 provides a method for preparing large Stokes-shifted perovskite nanocrystals based on disodium guanylate. The specific preparation process is as follows:

[0049] Lead iodide, cesium iodide, and disodium guanylate were mixed in a ball mill jar with a molar ratio of 1:1:0.5. Zirconia balls (ball-to-material ratio of 1:3) were added and the mixture was ball-milled at 1500 rpm for 25 minutes. After the first ball milling, disodium guanylate was added and the mixture was ball-milled at 1500 rpm for 25 minutes to obtain large Stokes displacement perovskite nanocrystals based on disodium guanylate.

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

[0051] 2. Comparative Example

[0052] Comparative Example 1

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

[0054] 3. Test Case

[0055] Experimental Example 1

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

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

[0058] Experimental Example 2

[0059] The perovskite nanocrystals obtained in Example 1 were analyzed using X-ray diffraction (XRD) analysis. See the results below. Figure 3 As shown.

[0060] Figure 3 This is the XRD pattern of the perovskite nanocrystals obtained in Example 1. (Observation) Figure 3 It can be seen that the prepared perovskite nanocrystal powder corresponds to the Cs4PbBr6 nanocrystal, with obvious characteristic peaks and no obvious angular shift. Therefore, the prepared perovskite nanocrystal is Cs4PbBr6 perovskite nanocrystal.

[0061] Experimental Example 3

[0062] The perovskite nanocrystals obtained in Example 1 and Comparative Example 1 were dispersed in chlorobenzene solution to prepare solutions with a concentration of 0.1 mg / mL. 2 mL of each solution was placed in a quartz four-way cuvette, and absolute fluorescence quantum yield was measured using an Edinburgh-made FLS 980 quantum yield module. The excitation source was a xenon lamp at 250 nm. The results are shown below. Figure 4-5 As 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 a graph showing the absolute fluorescence quantum yield of the perovskite nanocrystals obtained in Comparative 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%, while the absolute fluorescence quantum yield of the perovskite nanocrystals obtained in Comparative Example 1 is only 33.16%. Therefore, compared with the perovskite nanocrystals obtained using oleylamine as a ligand, the absolute fluorescence quantum yield of the perovskite nanocrystals obtained in this invention using disodium guanylate as a ligand is significantly improved.

[0064] Test Example 4

[0065] The perovskite nanocrystals obtained in Example 1 and Comparative Example 1 were dispersed in chlorobenzene solution to prepare solutions with a concentration of 0.1 mg / mL. Two mL of each solution was added to a quartz double-pass cuvette, and UV-Vis absorption spectroscopy was performed using a medium-speed scan in the 300-800 nm wavelength range. To remove the influence of background solvents during sample testing, 2 mL of pure chlorobenzene solvent was added to the double-pass cuvette for blank baseline scanning. The detection results are shown below. Figure 6-9 .

[0066] Figure 6-7 These are the UV-Vis absorption spectrum and photoemission spectrum of the perovskite nanocrystals obtained in Example 1, respectively. Figure 8-9 These are the UV-Vis absorption and photoemission spectra of the perovskite nanocrystals obtained in Comparative Example 1. (Observation) Figure 6 It can be seen that the perovskite nanocrystals obtained in Example 1 have two obvious absorption peaks at 330 nm and 365 nm, after which the absorption peak intensity decreases significantly, remaining below 10% at 520 nm. Observation Figure 7 It can be seen that the fluorescence emission peak position of the perovskite nanocrystals obtained in Example 1 is around 520 nm. Combined with... Figure 6 and Figure 7 It can be seen that the perovskite nanocrystals obtained in Example 1 effectively reduced the photon reabsorption effect.

[0067] Depend on Figure 8It can be seen that the perovskite nanocrystals obtained in Comparative Example 1 have a significant absorption peak at 330 nm, after which the absorption peak intensity begins to decrease, but still remains above 20% at 520 nm. Observation Figure 9 It can be seen that the fluorescence emission peak position of the perovskite nanocrystals obtained in Comparative Example 1 is around 520 nm. Combined with... Figure 8 and Figure 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-Vis absorption 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, resulting in a lower photon reabsorption effect, and thus are more suitable for application in optoelectronic devices.

[0069] The above are merely preferred embodiments of the present invention and are not limited to the examples described above. Those skilled in the art will recognize that various modifications and variations can be made based on the principles of the present invention. Any modifications or improvements made should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing guanosine disodium-based large Stokes shift perovskite nanocrystals, characterized by, The method comprises the following steps: The lead source and the cesium source are mixed for first ball milling, and then disodium guanylate is added for second ball milling, to obtain the large Stokes shift perovskite nanocrystal based on disodium guanylate.

2. The method of claim 1, wherein the guanosine disodium-based large Stokes shift perovskite nanocrystals are prepared by the method comprising the steps of: The molar ratio of the lead source, the cesium source and the disodium guanylate is 1:1:(0.25-0.5).

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

4. The method for preparing large Stokes-shifted perovskite nanocrystals based on disodium guanylate as described 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-shifted perovskite nanocrystals based on disodium guanylate as described in claim 1, characterized in that, The rotating speed of the first ball milling and the second ball milling is 1100-1500 rpm, and the ball milling time is 25-40 min.

6. The method for preparing large Stokes-shifted perovskite nanocrystals based on disodium guanylate as described in claim 1, characterized in that, The ball milling medium is zirconium oxide.

7. A guanosine disodium-based large Stokes shift perovskite nanocrystal, characterized in that, The method is prepared by the preparation method in any one of claims 1-6.

8. Use of guanosine disodium-based large Stokes shift perovskite nanocrystals according to claim 7, characterized in that, Application in the field of optoelectronic devices.

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