A method for preparing amino acid-modified Cs3Cu2I5 perovskite materials with enhanced fluorescence quantum yield

Abstract

The application relates to a kind of amino acid modified Cs3Cu2I5 perovskite materials and a preparation method thereof, and the amino acid is L-citrulline, L-histidine and 5-aminovaleric acid.The amino acid modified Cs3Cu2I5 perovskite is successfully synthesized by mixing and grinding a certain amount of amino acid with Cs3Cu2I5 perovskite based on a simple ball milling method, which is low in cost and can be obtained in an air environment.Firstly, due to the interaction between organic small molecules and perovskite, the above three kinds of amino acids can effectively passivate the defects of Cs3Cu2I5 perovskite, inhibit the non-radiative recombination of carriers, and at the same time, will not change the crystal structure of Cs3Cu2I5.Secondly, the addition of amino acid effectively improves the fluorescence performance of Cs3Cu2I5.Finally, the ball milling method used in the application does not produce solution pollutants, and the raw materials used are lead-free and non-toxic materials, which meets the concept of green environmental protection.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic display materials technology, and specifically relates to the preparation of a class of amino acid-modified Cs3Cu2I5 perovskite materials with enhanced fluorescence quantum yield. Background Technology

[0002] With the rapid development of the economy and society, people's demand for energy is increasing year by year. However, the energy model dominated by traditional fossil fuels such as oil and natural gas has many problems, mainly limited reserves and the tendency to cause environmental pollution. In the past decade or so, mankind has begun to search for green and sustainable energy to replace traditional fossil fuels. Renewable energy sources such as hydrothermal, geothermal, tidal, wind, and solar energy have become saviors of the energy crisis, especially solar energy, which is considered the most promising green renewable energy source. How to develop solar energy has become a key research focus, and thus, perovskite materials that can absorb solar energy and have a photoelectric effect have emerged.

[0003] Perovskite materials are a class of materials with excellent optical and electrical properties, such as high carrier mobility, tunable band gap, and good absorption coefficient. They are currently widely used in solar cells, lasers, diodes, and photodetectors, showing great application potential. However, most commonly used perovskites are lead-based perovskites with poor stability and inherent toxicity. Based on considerations of sustainable development and reducing environmental pollution, researchers have turned their attention to lead-free perovskites. Cs3Cu2I5 perovskite is a green copper-based perovskite, but it suffers from insufficient fluorescence efficiency and numerous inherent defects in device applications. Therefore, this invention develops a class of safe and environmentally friendly amino acid-modified Cs3Cu2I5 perovskites, which can effectively passivate defects, improve fluorescence efficiency, and effectively enhance photoelectric performance. Simultaneously, the addition of amino acids does not alter the original crystal structure. The amino acids selected in this invention are L-citrulline, L-histidine, and 5-aminovaleric acid, with L-glutamic acid, which has a different structure, used as a comparative example to highlight the enhancing effect of the three amino acids selected in this invention. Amino acids are generally composed of an amino group, a carboxyl group, and an R group; the different R groups result in a wide variety of amino acid structures. The R group of L-citrulline is an amide group, L-histidine has a cyclic imidazole group, 5-aminovaleric acid has a hydrocarbon carbon chain structure, and L-glutamic acid has a dicarboxyl group structure. This invention mainly explores the influence of different functional groups on the properties of perovskites. Applying amino acids to copper-based perovskites is a novel approach. Furthermore, this type of material is prepared using a mechanochemical ball milling method, which is environmentally friendly, avoids the use of solvents, is convenient and fast, and can provide high-yield, low-cost pure-phase products, aligning with the concept of sustainable development. Summary of the Invention

[0004] The main content of this invention is the synthesis of a fluorescence-enhanced, high-quantum-yield, and non-toxic amino acid-modified Cs3Cu2I5 perovskite via ball milling, wherein the amino acids are L-citrulline, L-histidine, and 5-aminovaleric acid. Due to the interaction between the organic small molecules and the perovskite, the above three amino acids can effectively passivate the defects of Cs3Cu2I5 perovskite and suppress the nonradiative recombination of charge carriers, without altering the crystal structure of Cs3Cu2I5.

[0005] The preparation of a class of amino acid-modified Cs3Cu2I5 perovskite materials with enhanced fluorescence quantum yield mainly adopts the following technical solutions:

[0006] (1) Place amino acids, cesium iodide and cuprous iodide into a grinding jar and mix them evenly in a certain proportion.

[0007] (2) Place the grinding jar from step (1) into a ball mill, set the rotation speed and grinding time, and grind thoroughly in the ball mill to obtain amino acid-modified Cs3Cu2I5 perovskite powder.

[0008] The amino acids mentioned in step (1) are L-citrulline, L-histidine, and 5-aminovaleric acid.

[0009] In step (1), the molar ratio of cesium iodide to cuprous iodide is 3:2, and the amino acid content is 0%, 0.5%, 1%, 1.5%, and 2% of the molar amount of cuprous iodide, respectively. Preferably, it is 1%.

[0010] The ball mill in step (2) is a planetary ball mill.

[0011] The rotational speed in step (2) is between 200 rpm and 500 rpm.

[0012] The grinding time in step (2) is 1h-3h.

[0013] In step (2), ball milling is also performed, and the required ball milling to raw material mass ratio is 20~50:1.

[0014] Taking any of the amino acid-modified Cs3Cu2I5 perovskites as an example, all processes are prepared in an air environment without the need to control humidity and temperature.

[0015] The beneficial effects of this invention are as follows:

[0016] In this invention, the amount of amino acids used is 0.5-2% of the molar amount of cuprous iodide, preferably 1%. Too little or too much is ineffective; too little will not achieve the passivation effect on perovskite, while too much will cause changes in local charge levels and affect the properties of the perovskite. Furthermore, the regulatory mechanism of amino acids on perovskite can be attributed to the following points:

[0017] First, amino acids can fix water molecules, which can reduce the water absorption of the perovskite surface and thus improve the stability of the perovskite.

[0018] Secondly, the amino acid contains a basic amino group, which can compensate for the insufficient ion matching of the vacancy coordination site in perovskite, thereby inhibiting phase separation and stabilizing the perovskite phase structure.

[0019] Third, compared to some metal ions and other additives, long-chain substances such as amino acids are less likely to enter the perovskite lattice and cause structural changes.

[0020] Fourth, regarding the chemical structure of amino acids, in addition to amino and carboxyl groups, special functional groups such as amide groups, cyclic imidazole groups, and hydrocarbon carbon chain structures can further enhance the properties of perovskites. Amide groups also contain amino groups, and amino acids with a double-amino structure have a better passivation effect than those with a single amino group; cyclic imidazole groups can make melanistic perovskites more stable (melanistic perovskites are perovskites that can effectively convert light energy into electrical energy, characterized by instability and a tendency to collapse back to a useless state); as for hydrocarbon carbon chain structures, amino acids with this functional group have significant steric hindrance, resulting in excellent surface passivation.

[0021] This invention utilizes a simple ball milling method to achieve the efficient synthesis of amino acid-modified Cs3Cu2I5 perovskite. The synthesized perovskite is non-toxic and lead-free. Furthermore, ball milling is a simple and green synthesis method, aligning with the concept of sustainable development. Compared to pure Cs3Cu2I5 perovskite, the fluorescence properties of amino acid-modified Cs3Cu2I5 perovskite are significantly improved. The fluorescence intensity of L-citrulline, L-histidine, and 5-aminovaleric acid-modified Cs3Cu2I5 perovskites is increased by 1.04, 1.36, and 1.41 times, respectively, with PLQY increasing by 6%, 16.68%, and 30.52%, respectively. In contrast, the comparative L-glutamic acid-modified Cs3Cu2I5 perovskite shows a significant decrease in luminescence intensity, which is attributed to the specific amino acid involved. Attached Figure Description

[0022] Figure 1 The optical images of pure Cs3Cu2I5, Cs3Cu2I5: L-citrulline (1%), Cs3Cu2I5: L-histidine (1%), and Cs3Cu2I5: 1% 5-aminovaleric acid under 254 nm excitation all show obvious blue light emission.

[0023] Figure 2The fluorescence emission spectra of Cs3Cu2I5 perovskite powders with L-citrulline contents of 0%, 0.5%, 1%, 1.5%, and 2% prepared under the same environment are shown. Among them, Cs3Cu2I5: 1% L-citrulline has the strongest fluorescence emission spectrum, which is about 1.04 times higher than that of pure Cs3Cu2I5.

[0024] Figure 3 The fluorescence emission spectra of Cs3Cu2I5 perovskite powders prepared under the same environment with L-histidine contents of 0%, 0.5%, 1%, 1.5%, and 2% are shown. Among them, Cs3Cu2I5:1.5% L-histidine has the strongest content, while Cs3Cu2I5:1% L-histidine has a slightly lower content. The optimal content is between 1-1.5%, which is about 1.36 times higher than that of pure Cs3Cu2I5.

[0025] Figure 4 The fluorescence emission spectra of Cs3Cu2I5 perovskite powders with 5-aminovaleric acid contents of 0%, 0.5%, 1%, 1.5%, and 2% prepared under the same environment are shown. Among them, Cs3Cu2I5:1% 5-aminovaleric acid has the strongest fluorescence emission spectrum, which is about 1.41 times higher than that of pure Cs3Cu2I5.

[0026] Figure 5 The fluorescence emission spectra of Cs3Cu2I5 perovskite powders with L-glutamic acid contents of 0%, 0.5%, 1%, 1.5%, and 2% prepared under the same environment are shown. The fluorescence intensity decreased after the addition of L-glutamic acid, indicating that glutamic acid does not have the fluorescence enhancement effect of L-citrulline, L-histidine, and 5-aminovaleric acid.

[0027] Figure 6 The PLQY of Cs3Cu2I5 perovskite modified with 1% L-citrulline, L-histidine and 5-aminovaleric acid respectively showed an increase of 6%, 16.68% and 30.52% respectively compared with pure Cs3Cu2I5.

[0028] Figure 7 The XRD pattern shows Cs3Cu2I5 perovskite modified with 1% each of L-citrulline, L-histidine, 5-aminovaleric acid and L-glutamic acid. It maintains the same phase structure as pure Cs3Cu2I5, indicating that the addition of amino acids does not change the phase of Cs3Cu2I5. Detailed Implementation

[0029] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims. Example 1

[0030] Step 1: Taking Cs3Cu2I5 perovskite without amino acid modification as an example, according to the stoichiometric ratio, a certain amount of cesium iodide and cuprous iodide are added to the ball mill jar in a molar ratio of 3:2 and mixed evenly. The ball milling time is 2 h and the speed is 300 rpm to obtain pure phase Cs3Cu2I5 perovskite powder. Example 2

[0031] Step 2: Taking Cs3Cu2I5 perovskite modified with 0.5% L-citrulline as an example, according to the stoichiometric ratio, a certain amount of cesium iodide, cuprous iodide, and L-citrulline are added to a ball mill jar and mixed evenly. The molar ratio of cesium iodide to cuprous iodide is 3:2, and the content of L-citrulline is 0.5% of the molar amount of cuprous iodide. The ball milling time is 2 h and the rotation speed is 300 rpm to obtain Cs3Cu2I5:0.5%L-citrulline perovskite powder. Example 3

[0032] Step 3: Taking Cs3Cu2I5 perovskite modified with 1% L-citrulline as an example, according to the stoichiometric ratio, a certain amount of cesium iodide, cuprous iodide, and L-citrulline are added to a ball mill jar and mixed evenly. The molar ratio of cesium iodide to cuprous iodide is 3:2, and the content of L-citrulline is 1% of the molar amount of cuprous iodide. The ball milling time is 2 h and the rotation speed is 300 rpm to obtain Cs3Cu2I5:1% L-citrulline perovskite powder. Example 4

[0033] Step 4: Taking 1% L-histidine modified Cs3Cu2I5 perovskite as an example, according to the stoichiometric ratio, a certain amount of cesium iodide, cuprous iodide, and L-histidine are added to a ball mill jar and mixed evenly. The molar ratio of cesium iodide to cuprous iodide is 3:2, and the content of L-histidine is 1% of the molar amount of cuprous iodide. The ball milling time is 2 h and the rotation speed is 300 rpm to obtain Cs3Cu2I5:1% L-histidine perovskite powder. Example 5

[0034] Step 5: Taking Cs3Cu2I5 perovskite modified with 2% 5-aminovaleric acid as an example, according to the stoichiometric ratio, a certain amount of cesium iodide, cuprous iodide, and 5-aminovaleric acid are added to a ball mill jar and mixed evenly. The molar ratio of cesium iodide to cuprous iodide is 3:2, and the content of 5-aminovaleric acid is 2% of the molar amount of cuprous iodide. The ball milling time is 2 h and the rotation speed is 300 rpm to obtain Cs3Cu2I5: 2% 5-aminovaleric acid perovskite powder.

[0035] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing amino acid-modified Cs3Cu2I5 perovskite materials with enhanced fluorescence quantum yield, characterized in that, Includes the following steps: (1) Place amino acids, cesium iodide, and cuprous iodide into a grinding jar and mix them evenly in a certain proportion; (2) Place the grinding jar from step (1) into a ball mill, set the rotation speed and grinding time, and grind thoroughly in the ball mill to obtain amino acid-modified Cs3Cu2I5 perovskite powder; The amino acid mentioned is one of L-citrulline, L-histidine, and 5-aminovaleric acid.

2. The method for preparing an amino acid-modified Cs3Cu2I5 perovskite material with enhanced fluorescence quantum yield according to claim 1, characterized in that, In step (1), the molar ratio of cesium iodide to cuprous iodide is 3:2, and the amount of amino acid used is 0.5-2% of the molar amount of cuprous iodide in the raw material.

3. The method for preparing an amino acid-modified Cs3Cu2I5 perovskite material with enhanced fluorescence quantum yield according to claim 1, characterized in that, The ball mill in step (2) is a planetary ball mill.

4. The method for preparing an amino acid-modified Cs3Cu2I5 perovskite material with enhanced fluorescence quantum yield according to claim 1, characterized in that, The rotational speed in step (2) is between 200 rpm and 500 rpm.

5. The method for preparing an amino acid-modified Cs3Cu2I5 perovskite material with enhanced fluorescence quantum yield according to claim 1, characterized in that, The grinding time in step (2) is 1h-3h.

6. The method for preparing an amino acid-modified Cs3Cu2I5 perovskite material with enhanced fluorescence quantum yield according to claim 1, characterized in that, In step (2), ball milling is also performed, and the required ball milling to raw material mass ratio is 20~50:1.

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