Ultrabroadband inorganic perovskite fluorescent material and preparation method thereof

Abstract

A preparation method of an ultrablu-ray inorganic perovskite fluorescent material, comprising: adding cesium carbonate powder into an oleic acid-toluene mixed solution, stirring and heating and drying under an inert gas atmosphere to prepare a cesium oleate precursor; adding lead bromide and zinc bromide powder into an oleic acid-oleylamine-toluene mixed solution, stirring and heating and drying under an inert gas atmosphere to prepare a reaction solution; adding the cesium oleate precursor into the prepared reaction solution for reaction; placing the reacted sample into an ice water bath to reduce the temperature to room temperature; and centrifuging and washing to obtain a high-efficiency ultrablu-ray fluorescent material. The inorganic perovskite fluorescent material prepared by the method can realize 433nm ultrablu-ray emission, the half peak width (FWHM) is about 12nm, and the quantum efficiency (PLQY) is as high as 97%.

Description

Technical Field

[0001] This invention relates to a high-efficiency ultra-blue light inorganic perovskite fluorescent material and its preparation method, belonging to the field of new optoelectronic functional material preparation technology. Background Technology

[0002] Inorganic perovskite materials, as a new generation of optoelectronic functional materials, have advantages such as direct band gap, high fluorescence quantum efficiency, high emission color purity, tunable emission color, large light absorption coefficient, high carrier mobility, high defect tolerance, and simple synthesis. They are widely used in LED, laser and electrical detection fields and have become a hot topic in the field of inorganic fluorescent materials.

[0003] Due to their inherent stability and high efficiency, inorganic perovskite materials for green and red light have been extensively studied and rapidly developed. These materials not only achieve narrow, tunable emission in the green and red wavelength range but also boast high quantum efficiencies (approaching 100%). In contrast, the development of blue light-emitting inorganic perovskite materials has lagged behind. In the 430–460 nm wavelength range, Cl- and Br- doping methods are commonly used to achieve blue light emission. However, the high electronegativity and small atomic radius of chlorine atoms increase surface and internal defects, resulting in lower quantum efficiencies (below 40%) and poor stability. Furthermore, Cl- and Br- doping methods require stringent experimental conditions, including unconventional environments such as vacuum, inert gases, and high temperatures, making synthesis complex. Reports on single-component cesium-lead-bromine blue light materials show that emission wavelengths with quantum efficiencies above 60% are often above 460 nm, while those emitting light in the 430–460 nm range typically have quantum efficiencies below 40%.

[0004] High requirements for synthesis conditions, low quantum efficiency, and poor stability are among the problems that urgently need to be solved in the development and application of blue light inorganic perovskite materials. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a method for preparing ultra-blue inorganic perovskite fluorescent materials.

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing an ultra-blue inorganic perovskite fluorescent material, characterized by the following steps:

[0008] Step 1: Cesium carbonate powder is added to a mixed solution of oleic acid and toluene, and the mixture is stirred, heated and dried under an inert gas atmosphere to prepare cesium oleate precursor;

[0009] Step 2: Add lead bromide and zinc bromide powders to a mixture of oleic acid, oleylamine, and toluene, and stir, heat, and dry under an inert gas atmosphere to prepare a reaction solution;

[0010] Step 3: Add the cesium oleate precursor prepared in Step 1 to the reaction solution prepared in Step 2 for reaction;

[0011] Step 4: Place the sample from Step 3 after the reaction is complete into an ice-water bath to cool it to room temperature;

[0012] Step 5: Centrifuge and clean the sample obtained in Step 4 to obtain high-efficiency ultra-blue fluorescent material.

[0013] Preferably, in step one, the amount of cesium carbonate is (200-814) mg, the amount of oleic acid is (0.88-2.5) ml, and the amount of toluene is (7.5-40) ml.

[0014] Preferably, the molar ratio of lead bromide to zinc bromide in step two is 1:(4-15).

[0015] Preferably, in step two, the amount of oleic acid is 0.5–4 ml and the amount of oleylamine is 0.5–4 ml.

[0016] Preferably, the inert gas atmosphere in steps one and two is nitrogen, argon, or other inert gas atmosphere.

[0017] Preferably, the stirring, heating and drying temperature in steps one and two is 80-100℃.

[0018] Preferably, the stirring, heating and drying time in steps one and two is 0.5 to 2 hours.

[0019] Preferably, the temperature of the reaction solution during the reaction in step three is 60–80°C.

[0020] Preferably, the reaction time in step three is 5 seconds to 3 minutes.

[0021] Preferably, in step five, the sample obtained in step four is first centrifuged to obtain the precipitate, dissolved in toluene, and then centrifuged again to obtain the supernatant.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. Compared to the conventional hot-injection method for preparing inorganic perovskite materials, this method is simpler and more convenient. It involves single-component synthesis, requires no doping, no vacuuming, and no excessively high heating temperatures. The prepared material only requires simple centrifugation to obtain relatively pure fluorescent materials, without the need for antisolvent cleaning.

[0024] 2. The preparation method of the present invention uses toluene instead of the octadecene solution commonly used in the hot injection method, which simplifies the sample purification steps. The prepared material can be purified by simple centrifugation to obtain relatively pure fluorescent material without the need for antisolvent washing, and the quantum efficiency is high.

[0025] 3. The inorganic cesium lead bromide perovskite fluorescent material prepared by the method described in this invention can achieve ultra-blue light emission at 433 nm, with a full width at half maximum (FWHM) of approximately 12 nm and a quantum efficiency (PLQY) as high as 97%. Attached Figure Description

[0026] Figure 1 This is the absorption and emission fluorescence spectrum of the ultra-blue inorganic perovskite fluorescent material of Example 1 of the present invention;

[0027] Figure 2 This is the XRD pattern of the ultra-blue inorganic perovskite fluorescent material of Embodiment 1 of the present invention;

[0028] Figure 3 This is a TEM image of the ultra-blue inorganic perovskite fluorescent material of Embodiment 1 of the present invention;

[0029] Figure 4 This is a side TEM image of the self-assembled ultra-blue inorganic perovskite fluorescent material of Embodiment 1 of the present invention.

[0030] Figure 5 This is a quantum efficiency measurement table of the ultra-blue light inorganic perovskite fluorescent materials in Examples 1-4 of this invention. Detailed Implementation

[0031] The principles and features of the present invention are described below with reference to examples. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0032] The reagents and materials used in the embodiments of this invention are all commercially available ordinary products.

[0033] Example 1

[0034] Step 1: Take 200 mg of cesium carbonate powder and add it to a mixed solution of 0.88 ml of oleic acid and 7.5 ml of toluene. Under an inert gas atmosphere, stir and heat at 100 °C for 0.5 h to dry the mixture and obtain the cesium oleate precursor.

[0035] Step 2: Take 70 mg of lead bromide and 523 mg of zinc bromide powder and add them to a mixture of 2 ml of oleic acid, 2 ml of oleylamine and 5 ml of toluene. Stir and heat at 100 °C for 0.5 h under an inert gas atmosphere to prepare the reaction solution.

[0036] Step 3: After drying, the reaction solution is cooled to 80°C, and the cesium oleate precursor prepared in Step 1 is added to the reaction solution prepared in Step 2 and reacted for 2.5 min.

[0037] Step 4: Place the sample from Step 3 after the reaction is complete into an ice-water bath to cool it to room temperature;

[0038] Step 5: Centrifuge the sample obtained in Step 4 at 3600 rpm for 10 min to collect the precipitate, then add 2 ml of toluene to the precipitate to dissolve it. After dissolving, centrifuge again at 3600 rpm for 5 min to collect the supernatant to obtain the perovskite fluorescent material. The material composition is CsPbBr3, the emission peak is at 437 nm, and the quantum efficiency is 90%.

[0039] The following describes the structural characterization and performance testing of the superblue inorganic perovskite material prepared in Example 1:

[0040] Absorption and emission spectra, such as Figure 1 As shown, the material has an absorption peak at 428 nm, an emission peak at 437 nm, and a Stokes shift of 9 nm.

[0041] X-ray diffraction analysis, such as Figure 2 As shown, compared with the standard PDF card of CsPbBr3, the peaks (100), (110), (200), (210), and (220) are consistent, proving that the material is a CsPbBr3 inorganic perovskite material.

[0042] High-resolution transmission electron microscopy characterization, such as Figure 3 and Figure 4 As shown, the material structure consists of nanosheets ranging from 20 to 200 nm. Figure 4 The diagram shows the side-mounted self-assembled structure, revealing that the nanosheet thickness is approximately 5 nm. This structure is consistent with its absorption peak and XRD pattern.

[0043] Figure 5 To measure the quantum efficiency of the sample using an integrating sphere, a toluene solution was used as the solvent. The measurement results in the table show that the sample's PLQY can reach 90%.

[0044] Example 2

[0045] A highly efficient superblue inorganic perovskite fluorescent material, with a CsPbBr3 composition, exhibits an emission peak at 433 nm and a quantum efficiency of 97%. Figure 5 As shown in the table, the specific synthesis process is similar to that in Example 1, except that:

[0046] In step two, the stirring and heating drying time at 100℃ is 1 hour.

[0047] In step three, the reaction temperature is 80℃ and the reaction time is 5 seconds.

[0048] Example 3

[0049] A highly efficient superblue inorganic perovskite fluorescent material, with a CsPbBr3 composition, exhibits an emission peak at 444 nm and a quantum efficiency of 87%. Figure 5 As shown in the table, the specific synthesis process is similar to that in Example 1, except that:

[0050] In step two, the amount of zinc bromide powder taken is 381 mg;

[0051] In step three, the reaction time at 80℃ is 3 minutes.

[0052] Example 4

[0053] A highly efficient superblue inorganic perovskite fluorescent material, with a CsPbBr3 composition, exhibits an emission peak at 450 nm and a quantum efficiency of 90%. Figure 5 As shown in the table, the specific synthesis process is similar to that in Example 1, except that:

[0054] In step two, take 381 mg of zinc bromide powder, add 1 ml of oleic acid and 1 ml of oleylamine.

[0055] In step three, the reaction time at 80℃ is 3 minutes.

[0056] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a super blue inorganic perovskite CsPbBr3 fluorescent material, characterized in that, The steps include the following: Step 1: Cesium carbonate powder is added to a mixed solution of oleic acid and toluene, and the mixture is stirred, heated and dried under an inert gas atmosphere to prepare cesium oleate precursor; Step 2: Add lead bromide and zinc bromide powders to a mixture of oleic acid, oleylamine, and toluene, and stir, heat, and dry under an inert gas atmosphere to prepare a reaction solution; Step 3: Add the cesium oleate precursor prepared in Step 1 to the reaction solution prepared in Step 2 for reaction; Step 4: Place the sample from Step 3 after the reaction is complete into an ice-water bath to cool it to room temperature; Step 5: First, centrifuge the sample obtained in Step 4 to collect the precipitate, add toluene to dissolve it, and then centrifuge again to collect the supernatant to obtain the high-efficiency ultra-blue fluorescent material.

2. The preparation method according to claim 1, characterized in that, In step one, the amount of cesium carbonate is (200~814) mg, the amount of oleic acid is (0.88~2.5) ml, and the amount of toluene is (7.5~40) ml.

3. The preparation method according to claim 1, characterized in that, In step two, the molar ratio of lead bromide to zinc bromide is 1:(4~15).

4. The preparation method according to claim 1, characterized in that, In step two, the amount of oleic acid is 0.5~4ml and the amount of oleylamine is 0.5~4ml.

5. The preparation method according to claim 1, characterized in that, The inert gas atmosphere in steps one and two is nitrogen or argon.

6. The preparation method according to claim 1, characterized in that, In steps one and two, the stirring, heating, and drying temperature is 80~100℃, and the stirring, heating, and drying time is 0.5~2h.

7. The preparation method according to claim 1, characterized in that, In step three, the temperature of the reaction solution is 60~80℃, and the reaction time is 5s~3min.

8. A super blue inorganic perovskite fluorescent material, characterized in that, It is prepared by any one of the preparation methods described in claims 1-7.

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