White-light-emitting copper-manganese-codoped two-dimensional cadmium-based perovskite crystal and preparation method thereof

Abstract

The invention belongs to the technical field of fluorescent materials, and particularly relates to a white-light-emitting copper-manganese co-doped two-dimensional cadmium-based perovskite crystal and a preparation method thereof.According to the preparation method, a simple and rapid improved anti-solvent assisted crystallization method is prepared, and a high-purity micron-sized crystal is successfully grown. The preparation method is simple, the raw material cost is low, the preparation of the white light single crystal can be realized by simply regulating and controlling the ratio of Mn to Cu, and the double adjustment of color temperature can be realized by changing the excitation wavelength and the ratio of Mn to Cu, so that the white light single crystal has a great application prospect in white light LEDs (Light Emitting Diodes).

Description

Technical Field

[0001] The present invention relates to the technical field of fluorescent materials, and particularly relates to a copper-manganese co-doped two-dimensional cadmium-based perovskite crystal with white light emission and a preparation method thereof. Background Art

[0002] In recent years, low-dimensional metal halide perovskites have received extensive attention due to their unique photophysical properties, excellent stability, simple synthesis, and structural diversity. In particular, white light-emitting perovskite materials have become a research hotspot due to their potential in single-component WLEDs. So far, a large number of 1D and 0D compounds based on Cu, Sn, Mn, In, and Cd have shown efficient white light emission of various STEs. However, the current library of white light-emitting two-dimensional (2D) perovskites is largely limited to lead-based (Pb) perovskites, but the toxicity of lead is a huge obstacle to its commercial application. Finding and developing two-dimensional perovskites with efficient white light emission remains a challenge.

[0003] Ion doping in low-dimensional metal halide perovskites has been successfully used as a method to adjust their optical properties. On the one hand, doping leads to local heterogeneity of the lattice, forming bright extrinsic STEs. On the other hand, some dopants, such as traditional metal Mn 2+ and some rare earth ions such as Er 3+ 、Ln 3+ etc., can bring additional ion emissions. For example, Sb 3+ / Mn 2+ co-doped 0D Cs3InCl6 NCs can exhibit strong white light emission, which is due to the combined contribution of the green light emission of Sb-induced STEs and the red light emission of Mn 2+4 T1→ 6 A1 transition. Therefore, multi-ion doping is a promising method to construct multiple emission centers to achieve efficient white light emission of two-dimensional perovskites. Summary of the Invention

[0004] To achieve the above object, the present invention provides a method for constructing a dual-emission center cadmium-based perovskite single crystal (PPDACdCl4) by co-doping with ions (Mn 2+ , Cu + ) to achieve color-tunable white light emission. By regulating the ratio of Mn 2+ , Cu + , micron-scale crystals with different color temperatures can be obtained. White light emission can be achieved at a specific ratio, and the preparation method is simple and fast, with low material cost.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A white light-emitting copper and manganese co-doped two-dimensional cadmium-based perovskite crystal and a preparation method thereof, comprising the following steps:

[0007] (1) Mix a certain amount of HCl and H3PO2 to obtain solution A, and mix a certain amount of H2O and H3PO2 to obtain solution B;

[0008] (2) Take a certain amount of PPDACl2 (PPDA = p-phenylenediamine) and CdCl2 and dissolve them in a certain amount of solution B, and ultrasonicate for a certain time to form a precursor solution C;

[0009] (3) Inject a certain amount of solution A into a certain amount of precursor solution C, shake well and then stand for a certain time to obtain PPDACdCl4 crystals;

[0010] (4) Take a certain amount of MnCl2 and CuCl and add them to solution A, then inject a certain amount of solution C into solution A containing Mn and Cu, shake the solution well and stand for a certain time to obtain Cu and Mn co-doped crystals.

[0011] Preferably, in step (1), the volume ratio of HCl to H3PO2 is 1:1, and the volume ratio of H2O to H3PO2 is 1:1.

[0012] Preferably, in step (2), the amount of PPDACl2 is 0.1 mmol - 0.2 mmol, the amount of CdCl2 is 0.13 mmol - 0.26 mmol, and the amount of solution B is 1 ml. Or the concentration of PPDACl2 is 0.1 mmol / ml - 0.2 mmol / ml, and the concentration of CdCl2 is 0.13 mmol / ml - 0.26 mmol / ml.

[0013] Preferably, in step (2), the ultrasonication time is 10 to 20 minutes, and the amount of solution C is 1 - 2 ml.

[0014] Preferably, in step (3), the amount of solution A is 1.2 - 2.4 ml.

[0015] Preferably, in step (4), the amount of MnCl2 is 1% - 200% of the amount of precursor CdCl2 in terms of the amount of substance, and the amount of CuCl is 1% - 100% of the amount of precursor CdCl2 in terms of the amount of substance.

[0016] Preferably, in steps (3) and (4), the standing time after shaking well is 5 - 10 minutes.

[0017] A Mn and Cu co-doped PPDACdCl4 crystal prepared by the present preparation method.

[0018] A method for realizing variable-color-temperature white light emission. The doped sample powder is irradiated with an ultraviolet lamp. When Mn and Cu in the precursor are in a certain proportion, the crystal can exhibit bright white light emission characteristics, and the color temperature of the white light can change with the change of the excitation wavelength; or the color temperature can be adjusted by changing the contents of Mn and Cu under the same excitation wavelength.

[0019] Preferably, when 80% Cu is doped with different proportions of Mn and irradiated with a 254-nm ultraviolet lamp, different luminescent colors are exhibited, changing from green dominated by Cu to red dominated by Mn, and white light emission appears at a certain proportion.

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

[0021] (1) The present invention provides a method for preparing PPDACdCl4 single crystal to realize adjustable-color-temperature white light by simply regulating the proportion of Mn 2+ and Cu + . The preparation method is simple and fast, the raw material cost is low, and the repeatability is high.

[0022] (2) The PPDACdCl4 crystals doped with Mn 2+ and Cu + provided by the present invention respectively have red light and green light emission. When doped with specific proportions of Mn 2+ and Cu + simultaneously, a white light emission with a color temperature changing with the excitation wavelength can be realized. Under the same excitation wavelength, the change of the white light color temperature can also be realized by adjusting the proportions of Mn 2+ and Cu + . Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art.

[0024] Figure 1 Synthesis schematic diagram of the Mn 2+ and Cu + co-doped PPDACdCl4 crystal prepared in Example 2 of the present invention;

[0025] Figure 2 Comparison diagram of the powder XRD of the PPDACdCl4 single crystal sample prepared in Example 1 of the present invention with the standard card;

[0026] Figure 3 SEM image of the Mn 2+ and Cu + co-doped PPDACdCl4 sample prepared in Example 2 of the present invention;

[0027] Figure 4 XRD pattern of the Mn 2+ , Cu + co-doped PPDACdCl4 sample prepared in Example 2 of the present invention;

[0028] Figure 5 XRD pattern of the Mn 2+ , Cu + luminescence image of the PPDACdCl4 crystal powder under 254 nm ultraviolet light at a specific doping ratio prepared in Example 2 of the present invention;

[0029] Figure 6 PL spectra of PPDACdCl4 doped with different ratios of Mn 2+ , Cu + prepared in Example 2 of the present invention under 254 nm excitation;

[0030] Figure 7 Time-resolved PL spectrum of PPDACdCl4 doped with 40% Mn and 80% Cu prepared in Example 2 of the present invention at room temperature;

[0031] Figure 8 CIE diagram of the spectra of PPDACdCl4 doped with different ratios of Mn 2+ , Cu + prepared in Example 2 of the present invention under 254 nm excitation;

[0032] Figure 9 Variable-excitation PL spectrum of PPDACdCl4 doped with 40% Mn and 80% Cu prepared in Example 2 of the present invention at room temperature;

[0033] Figure 10 Photoluminescence PL spectrum and device operation diagram of PPDACdCl4 doped with 40% Mn and 80% Cu prepared in Example 2 of the present invention. Detailed implementation manners

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention.

[0035] The present invention provides a copper-manganese co-doped two-dimensional cadmium-based perovskite crystal with white light emission and a preparation method, and the specific embodiments are as follows.

[0036] Example 1

[0037] Synthesis of PPDACdCl4 crystal:

[0038] (1) At room temperature, HCl and H3PO2 were mixed at a volume ratio of 1:1 to obtain solution A, and H3PO2 and H2O were mixed at a volume ratio of 1:1 to obtain solution B.

[0039] (2) 0.1 mmol of PPDACl2 and 0.13 mmol of CdCl2 were dissolved in 1 ml of solution B and sonicated for 10 minutes to form precursor solution C.

[0040] (3) 1.2 ml of solution A was injected into 1 ml of precursor solution C. The reaction solution was shaken well and allowed to stand for 5 minutes to obtain transparent PPDACdCl4 crystals. Finally, the crystals were washed with a small amount of absolute ethanol and dried in an oven for 24 hours. Dry and transparent small particle crystals could be obtained.

[0041] Example 2

[0042] Mn 2+ 、Cu + Synthesis of co-doped PPDACdCl4 crystals (synthesis schematic diagram as Figure 1 shown)

[0043] (1) At room temperature, HCl and H3PO2 were mixed at a volume ratio of 1:1 to obtain solution A, and H3PO2 and H2O were mixed at a volume ratio of 1:1 to obtain solution B.

[0044] (2) 0.1 mmol of PPDACl2 and 0.13 mmol of CdCl2 were dissolved in 1 ml of solution B and sonicated for 10 minutes to form precursor solution C.

[0045] (3) MnCl2·4H2O and CuCl based on x% and y% of the amount of substance of CdCl2 (x = 1 - 200, y = 1 - 100) were weighed separately, added to 1.2 ml of solution A, and sonicated for 10 minutes to dissolve. It was injected into 1 ml of precursor solution C. The reaction solution was shaken well and allowed to stand for 5 minutes to obtain Mn 2+ 、Cu + co-doped PPDACdCl4 crystals. Finally, the crystals were washed with a small amount of absolute ethanol and dried in an oven for 24 hours. Dry and transparent small particle crystals could be obtained.

[0046] Performance test:

[0047] The powder XRD of Example 1 was tested. As Figure 2 shown, it can be seen that the crystals rapidly precipitated by the improved anti-solvent assisted crystallization method corresponded very well with the calculated and simulated XRD, indicating that the prepared samples had high purity.

[0048] The SEM of Example 2 was tested. As Figure 3As shown, Mn can be seen 2+ , Cu + The co-doped PPDACdCl4 crystal shows obvious block shape, with a size of about 100 microns. Element mapping proves that the elements in the sample are evenly distributed.

[0049] Perform XRD test on Example 2. As Figure 4 shown, when co-doped with different ratios of Mn and Cu, there are no extra impurity peaks in the XRD of the sample, which proves that the doped ions effectively enter the crystal lattice. Moreover, with the increase of the doping ratio, the peaks of XRD do not show obvious shifts, indicating that the amount of ions entering is very small.

[0050] Irradiate the doped sample powder of Example 2 with an ultraviolet lamp. As Figure 5 shown, when doped with 80% Cu and different ratios of Mn, under the irradiation of a 254 nm ultraviolet lamp, it shows different emission colors, changing from green dominated by Cu to red dominated by Mn, and white emission appears at a certain ratio. And in Figure 6 the PL spectra of some doping ratios are given. The spectra show that the doping of Mn and Cu ions respectively constructs emission channels centered at 523 nm and 618 nm. Through Figure 7 the time-resolved PL spectra, the lifetimes at 523 nm and 618 nm under co-doping are fitted. Figure 8 The variable excitation spectra prove that they are two independent emission channels. By adjusting the doping ratios of the two ions, white light emission with variable color coordinates as shown in Figure 9 is obtained.

[0051] Perform LED demonstration on the sample co-doped with 80% Cu and 40% Mn in Example 2 as shown in Figure 10 and obtain the photoluminescence spectrum of the sample. The color coordinates are (0.4231, 0.4458), the color temperature is 3547 K, and the International Standard Illuminant Color Rendering Index is 86.7.

[0052] From the crystal prepared in the above Example 2, it can be seen that ion doping can effectively construct emission centers. Then, by skillfully controlling the amounts of Mn and Cu dopants, white light emission with adjustable color temperature can be achieved. Moreover, by changing the excitation wavelength, the luminescence of the crystal can also be adjusted, thus achieving a dual regulation effect, which has great application prospects in WLEDs.

[0053] The foregoing description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a two-dimensional cadmium-based perovskite crystal co-doped with copper and manganese for white light emission, characterized in that: The following steps are involved: (1) respectively mixing a certain amount of HCl and H3PO2 to obtain solution A and a certain amount of H2O and H3PO2 to obtain solution B; (2) taking a certain amount of PPDACl2 and CdCl2 and dissolving them in a certain amount of solution B, and ultrasonicating them for a certain period of time to form a precursor solution C; (3) injecting a certain amount of solution A into a certain amount of precursor solution C, shaking well, and then standing for a certain period of time to obtain PPDACdCl4 crystals; (4) A certain amount of MnCl2 and CuCl are added to solution A, and then a certain amount of solution C is injected into solution A containing Mn and Cu. The solution is shaken well and allowed to stand for a certain period of time to obtain Cu, Mn co-doped crystals.

2. The method for preparing the white light emitting copper-manganese co-doped two-dimensional cadmium-based perovskite crystal according to claim 1, characterized in that: In step (1), the volume ratio of HCl to H3PO2 is 1:1, and the volume ratio of H2O to H3PO2 is 1:

1.

3. The method for preparing the white light emitting copper-manganese co-doped two-dimensional cadmium-based perovskite crystal according to claim 1, characterized in that: In step (2), the amount of PPDACl2 is 0.1mmol-0.2mmol, the amount of CdCl2 is 0.13mmol-0.26mmol, and the amount of solution B is 1ml; or the concentration of PPDACl2 is 0.1mmol / ml-0.2mmol / ml, and the concentration of CdCl2 is 0.13mmol / ml-0.26mmol / ml.

4. The method for preparing the white light emitting copper-manganese co-doped two-dimensional cadmium-based perovskite crystal according to claim 1, characterized in that: In step (2), the ultrasonic time is 10 to 20 minutes, and the amount of solution C is 1-2 ml.

5. The method for preparing the white light emitting copper-manganese co-doped two-dimensional cadmium-based perovskite crystal according to claim 1, characterized in that: In step (3), the amount of solution A is 1.2-2.4 ml.

6. The method for preparing the white light emitting copper-manganese co-doped two-dimensional cadmium-based perovskite crystal according to claim 1, characterized in that: In step (4), the amount of MnCl2 is 1%-200% based on the amount of the precursor CdCl2 substance, and the amount of CuCl is 1%-100% based on the amount of the precursor CdCl2 substance.

7. The method for preparing the white light emitting copper-manganese co-doped two-dimensional cadmium-based perovskite crystal according to claim 1, characterized in that: In steps (3) and (4), the mixture is allowed to stand for 5-10 minutes after being shaken.

8. A Mn, Cu co-doped PPDACdCl4 crystal obtained by the preparation method according to any one of claims 1 to 7.

9. A method for achieving variable color temperature white light emission using the crystal prepared according to claim 8, characterized in that: The doped sample powder is irradiated with ultraviolet light. When Mn and Cu in the precursor are in a certain proportion, the crystal can exhibit bright white light emission characteristics and the color temperature of the white light can change with the change of the excitation wavelength; or the color temperature can be adjusted by changing the content of Mn and Cu at the same excitation wavelength.

10. The method for realizing variable color temperature white light emission according to claim 9, characterized in that: When doped with 80% Cu and different proportions of Mn, it exhibits different luminescent colors under 254nm ultraviolet light, changing from Cu-dominated green to Mn-dominated red, and white luminescence appears under a certain proportion.

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