Fluorine-doped lead-free all-inorganic metal halide perovskite luminescent material and preparation method thereof

Abstract

According to the fluorine-doped lead-free all-inorganic metal halide perovskite luminescent material and the preparation method thereof, F is introduced into a precursor, halogen ions of halogen sites in lead-free all-inorganic perovskite can be partially replaced with F, and due to the fact that F has the extremely small ion radius (about 1.33), the fluorine-doped lead-free all-inorganic metal halide perovskite luminescent material can be used for preparing the lead-free all-inorganic metal halide perovskite luminescent material. The doping of the material usually causes significant local lattice distortion, thereby changing the lattice structure and energy band characteristics of the material. These properties make Fa ideal choice to regulate the luminescent properties of metal halide perovskite and related materials. The fluorescence quantum yield (PLQY) of the original lead-free all-inorganic perovskite material of CsCdCl3 is 19.20%, and the fluorescence quantum yield of the all-inorganic perovskite material introduced with F can reach 97.55%.

Description

Technical Field

[0001] The present invention belongs to the field of all-inorganic halide perovskite luminescent materials, and specifically relates to a method of − A method to significantly enhance the luminescent properties of lead-free all-inorganic perovskites by doping. Background Art

[0002] Metal halide perovskite materials have attracted extensive attention in the fields of light-emitting diodes and long afterglow luminescence due to their excellent optoelectronic properties. However, Cd-based all-inorganic metal halide perovskites have low luminescence intensity and short afterglow lifetime, which makes it difficult to meet the requirements of high-efficiency luminescence and long-life applications. At the same time, defect states in the lattice are prone to increase non-radiative recombination, further reducing the luminescence efficiency. − Due to its unique physical and chemical properties, it is widely used in the field of materials science, especially in regulating the structure and performance of materials. − It has the highest electronegativity of all anions, with an electronegativity value of 4.0, which enables it to significantly affect the electron distribution and local electric field in the material. − With an extremely small ionic radius (about 1.33 Å), its doping usually induces significant local lattice distortion, thereby changing the lattice structure and energy band characteristics of the material. − It is an ideal choice for regulating the luminescence properties of metal halide perovskites and related materials. Summary of the invention

[0003] In order to solve the above problems, the present invention proposes a fluorine-doped non-lead all-inorganic metal halide perovskite luminescent material, by introducing part of F into the halogen sites in the non-lead all-inorganic perovskite. − , in order to significantly change the luminescence properties of its lead-free all-inorganic perovskite materials.

[0004] The fluorine-doped non-lead all-inorganic metal halide perovskite light-emitting material has ABX n :F − Ternary structure; Among them, A represents Rb + or Cs + Cation, B represents Mn 2+ Sn 2+ , Cu + or Cd 2+ metal cation, X represents a halide ion, the halide ion is Cl − Br − or I − ; F − The molar concentration range is 0.1%~45%, n=3, 4, 5 or 6.

[0005] Preferably, ABX n:F − The ternary structure is CsCdCl3:F − 、Cs2CdCl4:F − or RbCdCl3:F − 、Rb4CdCl6:F − 、CsCdBr3:F − 、Cs2CdBr4:F − 、Cs3CdBr5:F − 、Rb4CdBr6:F − 、Cs2CdI4:F − One of them.

[0006] The present invention also provides a F − The preparation method of the doped non-lead all-inorganic metal halide perovskite light-emitting material comprises the following specific steps: 1) Preparation of A-site metal ions, B-site metal ions, halogen ions, hydrochloric acid and F − The composition contains F − The precursor solution of − Added in the form of A-site metal ion salt or B-site metal ion salt or hydrofluoric acid, and added at a rate of 2.0 to 28.5 mol per mole of perovskite crystal; 2) Precipitate the crystals from the precursor solution to obtain F − Doped non-lead all-inorganic metal halide perovskite light-emitting materials.

[0007] Preferably, in step 1), F − Add 22.0~24.0 mol per mole of perovskite crystal.

[0008] Preferably, in step 1), the precursor solution is prepared according to a molar ratio of A-site metal ions, B-site metal ions, and halogen ions of 1:1:n, where n=3, 4, 5 or 6.

[0009] Preferably, the method for precipitating crystals from the precursor solution in step 2) is cooling crystallization.

[0010] Beneficial effects of the present invention: In the present invention, by introducing F into the precursor − The halide ions in the lead-free all-inorganic perovskite can be partially replaced by F − , due to F − The halogen ions have significantly different ionic radius from the host perovskite, which usually induces significant local lattice distortion, reduces the self-trapping barrier, inhibits non-radiative recombination, and improves the luminescence efficiency.

[0011] The fluorescence quantum yield of the original lead-free all-inorganic perovskite material CsCdCl3 is 19.20%, while the introduction of F− The fluorescence quantum yield of the final all-inorganic perovskite material can reach 97.55%.

[0012] The preparation method of the lead-free all-inorganic perovskite material provided by the present invention and F − The doping method is simple to operate and low in cost. The obtained lead-free all-inorganic perovskite material has high fluorescence quantum yield and good stability. With the continuous development of lead-free all-inorganic perovskite materials, it has broad application prospects in the fields of luminescence and display. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The CsCdCl3:F prepared in Example 1 − XRD spectra of inorganic perovskite materials.

[0014] Figure 2 The CsCdCl3:F prepared in Example 1 − Excitation-emission spectra of inorganic perovskite materials.

[0015] Figure 3 The CsCdCl3:F prepared in Example 1 − Fluorescence quantum yield spectra of inorganic perovskite materials.

[0016] Figure 4 The CsCdCl3:F prepared in Example 1 − Crystal luminescence photograph of inorganic perovskite material under 254 nm excitation conditions. DETAILED DESCRIPTION

[0017] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are selected according to conventional methods and conditions, or according to the product specifications. The hydrochloric acid and hydrofluoric acid used in the present invention refer to undiluted commercially available 37% concentrated hydrochloric acid and commercially available 40% concentrated hydrofluoric acid, respectively.

[0018] Example 1 In this embodiment, F − Taking the doping of CsCdCl3 single crystal material with a lead-free all-inorganic perovskite structure as an example, the synthesis method is introduced. The specific steps are as follows: 1) Dissolve 1 mmol of cesium chloride, 1 mmol of cadmium chloride, 2 mL of hydrochloric acid and 1 mL of hydrofluoric acid in a polytetrafluoroethylene liner and stir slowly at room temperature for 30 min until completely dissolved; 2) The reactor equipped with the liner was placed in an oven and gradually heated from room temperature to 220°C for 2 hours, and then slowly cooled to room temperature to obtain CsCdCl3:F with high purity and enhanced fluorescence efficiency. −Inorganic perovskite crystalline materials.

[0019] The product was subjected to powder XRD test, and its XRD spectrum was as follows: Figure 1 As shown; the fluorescence excitation-emission spectrum is shown Figure 2 Its fluorescence quantum yield spectrum is shown in Figure 3 As shown in Figure 2, the fluorescence quantum yield can reach 97.55%; the luminescence photo of the crystal under 254 nm excitation is shown in Figure 2. Figure 4 shown.

[0020] Embodiment 2~6 The difference of this embodiment is that the amount of HF added in step 1) of embodiment 1 is changed from 1 mL to 0.00 mL, 0.25 mL, 0.50 mL, 0.75 mL and 1.25 mL respectively, and other conditions remain unchanged.

[0021] The fluorescence quantum yields of the products with different amounts of HF added were tested, and the values ​​of Examples 2 to 6 were 19.20%, 30.74%, 50.28%, 69.81%, and 79.36%, respectively. Therefore, the optimal amount of HF added was 1 mL. The increase in the amount of HF added was conducive to the luminescence efficiency of the obtained product, but too much HF would lead to quenching of the fluorescence concentration.

[0022] The above only gives the preferred embodiments of the present invention, which does not represent the full scope of the present invention. The scheme proposed by the present invention can theoretically be applied to all Mn 2+ Sn 2+ , Cu + and Cd 2+ Metal cation-based lead-free all-inorganic perovskite materials.

Claims

1. A fluorine-doped non-lead all-inorganic metal halide perovskite luminescent material, characterized in that: The perovskite material has ABX n :F − Ternary structure; ABX n :F − In the ternary structure, A represents Rb + or Cs + Cation, B represents Mn 2+ Sn 2+ , Cu + or Cd 2+ metal cation, X represents a halide ion, the halide ion is Cl − Br − or I − ; F − The molar percentage concentration is 0.1%~45%, n=3, 4, 5 or 6.

2. The fluorine-doped lead-free all-inorganic metal halide perovskite light-emitting material according to claim 1, characterized in that: ABX n :F − The ternary structure is CsCdCl3:F − 、Cs2CdCl4:F − or RbCdCl3:F − 、Rb4CdCl6:F − 、CsCdBr3:F − 、Cs2CdBr4:F − 、Cs3CdBr5:F − 、Rb4CdBr6:F − 、Cs2CdI4:F − One of them.

3. A method for preparing the fluorine-doped lead-free all-inorganic metal halide perovskite luminescent material as claimed in claim 1, characterized in that: The specific steps of this method are as follows: 1) Preparation of A-site metal ions, B-site metal ions, halide ions, hydrochloric acid and F − The composition contains F − The precursor solution of − The halogen ion is added in the form of a metal ion salt at position A or a metal ion salt at position B or hydrofluoric acid, and is added at a rate of 2.0 to 28.5 mol per mole of perovskite crystal; the halogen ion is Cl − Br − or I − ; 2) Precipitate the crystals from the precursor solution to obtain F − Doped non-lead all-inorganic metal halide perovskite light-emitting materials.

4. The method for preparing the fluorine-doped lead-free all-inorganic metal halide perovskite luminescent material according to claim 3, characterized in that: Step 1) Medium F − Add 22.0~24.0 mol per mole of perovskite crystal.

5. The method for preparing the fluorine-doped lead-free all-inorganic metal halide perovskite luminescent material according to claim 3, characterized in that: In step 1), the precursor solution is prepared according to the molar ratio of A-site metal ion, B-site metal ion and halogen ion of 1:1:n, where n=3, 4, 5 or 6.

6. The method for preparing the fluorine-doped lead-free all-inorganic metal halide perovskite luminescent material according to claim 3, 4 or 5, characterized in that: Step 2) The method for precipitating crystals from the precursor solution is cooling crystallization.

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