Multi-band luminescent perovskite afterglow material and preparation method thereof

Abstract

The application discloses a multi-waveband light-emitting perovskite afterglow material and a preparation method thereof. The material is a matrix material, and an expression formula is ABa-xBaxI3-yCIy, wherein a value range of x is 0.5-0.7, and a value range of y is 0.05-0.4. The material has not only good cyan fluorescence and cyan afterglow, but also near-infrared fluorescence characteristics. The application can be applied to manufacturing a new type of light-emitting diode, which emits cyan fluorescence after being excited by specific light in a visible light wave band, exhibits cyan afterglow under specific conditions, and emits near-infrared light after being excited by specific light in a near-infrared light wave band. In the emergency lighting field, the application can be used to design an emergency sign with high visibility, soft light emission and long duration. In the security anti-counterfeiting field, the application can be used to design an anti-counterfeiting sign with high security and difficult to counterfeit.

Description

Technical Field

[0001] This invention relates to the field of lead-free luminescent perovskite materials, and particularly to a multi-band luminescent perovskite afterglow material and its preparation method. Background Technology

[0002] In recent years, perovskite materials have become a hot topic in physics research due to their excellent photoelectric properties and tunable optical characteristics. Their superior photoelectric conversion efficiency makes perovskite materials an important research subject in new energy materials, and with the continuous development of perovskite material research, they have shown great potential in many fields such as optoelectronic devices and biomedical imaging.

[0003] However, most traditional perovskite materials are lead-containing. Although lead-containing perovskite materials have performed well in the optoelectronic field, especially in applications such as solar cells and light-emitting diodes, their widespread application still faces many challenges and limitations.

[0004] First, lead-containing perovskite materials not only pollute the environment but also harm human health. During production, use, and disposal, these materials may release lead ions, polluting soil and water sources and disrupting the ecological balance.

[0005] Lead is a recognized toxic heavy metal that can cause serious harm to human health. Long-term exposure to lead may lead to damage to the nervous system, kidney damage, reproductive problems, and cognitive impairment.

[0006] Secondly, existing lead-containing perovskite materials exhibit relatively limited emission wavelengths due to constraints imposed by their crystal structure and compositional limitations. Classic chlorine-based lead-containing perovskites emit light primarily in the deep blue region of 410–430 nm; bromine-based lead-containing perovskites typically emit green light in the 520–535 nm range; and iodine-based lead-containing perovskites mostly emit light in the near-infrared region around 760 nm. These materials are largely concentrated in a single emission wavelength, making it difficult to achieve multi-wavelength coexistence. Summary of the Invention

[0007] To overcome the aforementioned shortcomings and deficiencies of the prior art, the present invention aims to provide a multi-band luminescent lead-free perovskite afterglow material, in order to... Using bismuth and neodymium ions as the matrix material, and co-doping with bismuth and neodymium ions, the crystal material of this invention exhibits cyan fluorescence and cyan afterglow characteristics at a specific bismuth ion doping concentration. The introduction of neodymium ions not only enhances emission in the cyan band but also introduces luminescence in the infrared band, covering 800-1500 nm, with a broader emission peak range, thus expanding the... Applications of light-emitting perovskite materials in optoelectronic devices.

[0008] Another objective of this invention is to provide a method for preparing the above-mentioned multi-band luminescent perovskite afterglow material. When a preferred heating scheme is used, not only is the cyan fluorescence emission enhanced, but the preparation reaction time is also greatly shortened.

[0009] The objective of this invention is achieved through the following technical solution:

[0010] This invention provides a multi-band luminescent perovskite afterglow material, which... As the matrix material, with bismuth and neodymium ions as dopant ions, the expression is: The value of x ranges from 0.5 to 0.7, and the value of y ranges from 0.05 to 0.4.

[0011] Preferably, the value of y is in the range of 0.1 to 0.2.

[0012] Preferably, the expression for the multi-band luminescent perovskite afterglow material is as follows: .

[0013] This invention also provides the aforementioned multi-band luminescent perovskite afterglow material, comprising the following steps:

[0014] S1: Weigh calcium carbonate, tin dioxide, bismuth source, and neodymium source according to the expression;

[0015] S2: Grind the raw material obtained by weighing in step S1 thoroughly;

[0016] S3: The powder ground in step S2 undergoes a high-temperature solid-phase reaction in a high-temperature heating device;

[0017] S4: Cooling annealing yields multi-band luminescent perovskite afterglow material.

[0018] Preferably, step S2 involves thoroughly grinding the raw material obtained by weighing in step S1, specifically as follows:

[0019] Add the raw material weighed in step S1 to the grinding media and grind it thoroughly with the grinding media rod for 25-30 minutes.

[0020] Preferably, the bismuth source is bismuth trioxide and the neodymium source is neodymium trioxide.

[0021] Preferably, the powder after grinding in step S3 undergoes a high-temperature solid-phase reaction in a high-temperature heating device, specifically as follows:

[0022] The ground powder is placed in an alumina crucible and then placed in a high-temperature heating device for a high-temperature solid-phase reaction; the high-temperature heating device is a muffle furnace with a built-in muffle furnace door plug.

[0023] Preferably, in the high-temperature solid-state reaction, the heating process is as follows: heating from room temperature to 880~920℃ for 175~185 minutes; then holding at 880~920℃ for 115~125 minutes; continuing to heat from 880~920℃ to 1380~1420℃ for 115~125 minutes; and then holding at 1380~1420℃ for 175~185 minutes.

[0024] Preferably, the cooling annealing in step S4 specifically involves natural cooling within the muffle furnace.

[0025] This invention also provides a luminescent perovskite afterglow material, which... As the matrix material, with bismuth ions as dopant ions, the expression is: , where x ranges from 0.5 to 0.7.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] (1) The multi-band luminescent perovskite afterglow material of the present invention uses lead-free perovskite material. Using a substrate, a lead-free doped perovskite material was successfully synthesized by double doping with specific concentrations of bismuth and neodymium ions. In the visible light band, this crystal material exhibits cyan fluorescence and cyan afterglow; in the near-infrared band, it exhibits near-infrared fluorescence and red afterglow. This invention leverages the unique advantage of multi-band emission, making multi-band luminescent perovskite afterglow materials promising for various applications. These materials can be used to manufacture novel light-emitting diodes (LEDs), enabling them to emit standard 460nm blue light upon excitation by specific light, serving as a low-power, self-emissive blue light source; to emit near-infrared light upon excitation by specific light, for optical communication and sensing; and to exhibit cyan afterglow under specific conditions, filling the cyan gap in traditional LEDs, improving spectral continuity, expanding the color gamut and color saturation of LEDs, and further broadening their functionality and application range. In emergency lighting, the cyan afterglow and cyan fluorescence characteristics exhibited by the material under different excitation conditions can be used to design emergency signs with high visibility, soft light emission, and long duration, effectively enhancing the product's emergency lighting capabilities. In security and anti-counterfeiting, the red afterglow and near-infrared fluorescence characteristics exhibited by the material under different excitation conditions can be used to design highly secure and difficult-to-counterfeit anti-counterfeiting signs, effectively improving the product's anti-counterfeiting capabilities.

[0028] (2) The multi-band luminescent perovskite afterglow material of the present invention, using the optimized high-temperature solid-state method of the present invention, not only enhances the emission of cyan fluorescence, but also greatly shortens the preparation reaction time.

[0029] (3) The luminescent perovskite afterglow material of the present invention is made of lead-free perovskite material. Based on the bismuth ion doping of the present invention at a specific concentration, the luminescent perovskite afterglow material exhibits cyan fluorescence and cyan afterglow characteristics, which can fill the cyan gap in traditional LEDs, improve spectral continuity, expand the color gamut and color saturation of LEDs, and further enhance the functionality and application range of LEDs. Attached Figure Description

[0030] Figure 1 This is a flowchart illustrating the optimized high-temperature solid-state preparation method according to an embodiment of the present invention.

[0031] Figure 2 This is a flowchart illustrating the preparation process of a conventional high-temperature solid-state method according to an embodiment of the present invention.

[0032] Figure 3 The emission spectra (350-1500nm) of samples 1 and 5-6 under 312nm detection in the embodiments of the present invention are shown.

[0033] Figure 4 The emission spectra of samples 1-3 under 312nm detection are shown in the embodiments of the present invention.

[0034] Figure 5 The emission spectra (visible light band) of samples 1 and 5-6 under 312nm detection in the embodiments of the present invention are shown.

[0035] Figure 6 The emission spectra (near-infrared band) of samples 1 and 5-6 under 585nm detection in the embodiments of the present invention are shown.

[0036] Figure 7 The images show comparisons of samples 1-7 observed under sunlight (labeled as sunlight in the figures), irradiated with 254nm ultraviolet light in a dark room (labeled as 254nm in the figures), and after the ultraviolet light source was removed (labeled as afterglow in the figures) in embodiments of the present invention.

[0037] Figure 8 The PL spectra of samples 5 and 8 under 312nm excitation in the embodiments of the present invention are shown. Detailed Implementation

[0038] The present invention is further described below through specific embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0039] In the following embodiments, the information on the raw materials used to prepare the perovskite crystals of the present invention is shown in Table 1 below:

[0040] Table 1. Raw materials used to prepare the perovskite crystals of this invention.

[0041]

[0042] Example 1

[0043] The lead-free doped perovskite material prepared in this embodiment is bismuth ion ( A single-doped crystal has the following structural formula: The molar doping concentrations are 0.6%, 1%, and 2%, respectively, i.e., x = 0.6, 1, 2.

[0044] This embodiment uses an optimized high-temperature solid-state method to prepare three lead-free doped perovskite material samples. The preparation process is as follows (e.g. Figure 1 (Flowchart shown): First, according to the ingredient list in Table 2 below, weigh CaCO3, SnO2, and Bi2O3 using an analytical balance, and then use a wash bottle to dispense 15 mL of C2H6O.

[0045] Table 2. Material composition table of the three lead-free doped perovskite material samples in this embodiment.

[0046] <![CDATA[CaCO3]]> <![CDATA[SnO2]]> <![CDATA[Bi2O3]]> Sample 1: 0.6% Bi 1mmol 1mmol 0.006mmol Sample 2: 1% Bi 1mmol 1mmol 0.01mmol Sample 3: 2% Bi 1mmol 1mmol 0.02mmol

[0047] The above raw materials were separately added to a solution that had been washed with a small amount of anhydrous ethanol. In the inner diameter agate grinding body, use an agate mortar and pestle to grind slowly and evenly for 25-30 minutes to obtain a white, uniform powder.

[0048] Use a stainless steel medicine spoon to scoop the medicine and place it into an alumina crucible that has been cleaned with anhydrous ethanol.

[0049] The alumina crucible was heated from room temperature to [temperature value] using a muffle furnace. The heating time is 180 minutes; then... Keep warm for a period of time, 120 minutes; continue from... Heat to The heating time is 120 minutes; then in Keep warm for a period of time, the warming time is 180 minutes.

[0050] After the heating process, the alumina crucible is placed in a muffle furnace with a door plug and allowed to cool naturally at room temperature. Once cooled to room temperature, the crystals in the crucible are extracted.

[0051] The extracted crystals were ground again with an agate mortar for 15-25 minutes. The crystals were then dried in a fume hood and finally stored in plastic tubes or sample bags for later characterization and testing.

[0052] Example 2

[0053] The lead-free doped perovskite material in this embodiment is doped with both bismuth and neodymium ions, and its structural formula is as follows: Bi 3+The molar doping concentration was fixed at 0.6% (i.e., x = 0.6), Nd 3+ The molar doping concentrations are 0.05%, 0.1%, 0.2%, and 0.4%, respectively, i.e., y = 0.05, 0.1, 0.2, and 0.4.

[0054] This embodiment uses an optimized high-temperature solid-state method to prepare four lead-free doped perovskite material samples. The preparation process is as follows (e.g. Figure 1 (Flowchart shown): First, according to the ingredient list in Table 3 below, use an analytical balance to weigh CaCO3, SnO2, and Bi2O. 3、 Nd2O3 was used, and 15 mL of C2H6O was collected using a wash bottle.

[0055] Table 3. Material composition table of four lead-free doped perovskite material samples in this embodiment.

[0056] <![CDATA[CaCO3]]> <![CDATA[SnO2]]> <![CDATA[Bi2O3]]> <![CDATA[Nd2O3]]> Sample 4: 0.6% Bi 0.05% Nd 1mmol 1mmol 0.006mmol 0.0005 mmol Sample 5: 0.6% Bi 0.1% Nd 1mmol 1mmol 0.006mmol 0.001 mmol Sample 6: 0.6% Bi 0.2% Nd 1mmol 1mmol 0.006mmol 0.002 mmol Sample 7: 0.6% Bi 0.4% Nd 1mmol 1mmol 0.006mmol 0.004 mmol

[0057] The above raw materials were separately added to a solution that had been washed with a small amount of anhydrous ethanol. In the inner diameter agate grinding body, use an agate mortar and pestle to grind slowly and evenly for 25-30 minutes to obtain a white, uniform powder.

[0058] Use a stainless steel medicine spoon to scoop the medicine and place it into an alumina crucible that has been cleaned with anhydrous ethanol.

[0059] The alumina crucible was heated from room temperature to [temperature value] using a muffle furnace. The heating time is 180 minutes; then... Keep warm for a period of time, 120 minutes; continue from... Heat to The heating time is 120 minutes; then in Keep warm for a period of time, the warming time is 180 minutes.

[0060] After the heating process, the alumina crucible is placed in a muffle furnace with a door plug and allowed to cool naturally at room temperature. Once cooled to room temperature, the crystals in the crucible are extracted.

[0061] The extracted crystals were ground again with an agate mortar for 18 minutes. The crystals were then dried in a fume hood and finally stored in plastic tubes or sample bags for later characterization and testing.

[0062] Example 3

[0063] In this embodiment, the structure prepared using the traditional high-temperature solid-state method is as follows: The lead-free doped perovskite material, designated as sample 8, was prepared as follows (e.g., ...). Figure 2 (Flowchart shown)

[0064] First, weigh using an analytical balance. Use a wash bottle to collect 100 mL of C2H6O.

[0065] Pour the above raw materials into a ball mill jar containing agate grinding balls, and add 50 mL of C2H6O.

[0066] Place the grinding jar into the balanced planetary ball mill and run it at 500 r / min for 30 min.

[0067] After ball milling, rinse the raw material mixture into an evaporating dish with about 20 mL of the rinsing liquid.

[0068] The evaporating dish containing the raw material mixture was placed in an oven and dried at 45°C until a white, dry film sample was obtained.

[0069] Use a stainless steel spoon to scrape off a thin film sample, place it in an agate mortar and grind it until white, uniform particles are obtained, and then put it into an alumina crucible.

[0070] The alumina crucible was heated from room temperature to [temperature value] using a muffle furnace. The heating time is 180 minutes; then... Keep warm for 120 minutes; after cooling to room temperature, grind and mix again using an agate mortar and pestle, and then place in an alumina crucible.

[0071] The alumina crucible was heated from room temperature to [temperature value] using a muffle furnace. The heating time is 240 minutes; then... The sample was kept at a certain temperature for 180 minutes; after cooling to room temperature, it was ground and mixed three more times using an agate mortar and pestle to obtain the final sample.

[0072] test:

[0073] In embodiments of the present invention, a fluorescence spectrometer was used to test the fluorescence emission spectrum (PL spectrum) of the prepared crystal sample in the 350-1500 nm range. The results are as follows: Figures 3-6 and Figure 8 As shown.

[0074] Figure 3 The emission spectra (350-1500nm) of samples 1 and 5-6 are obtained under 312nm detection.

[0075] Figure 4 The images show the emission spectra of samples 1-3 under 312nm excitation. As can be seen from the figures, under 312nm excitation, different doping concentrations... The emission spectrum peaks of the crystals are roughly consistent, with small emission peaks appearing at 350-400 nm and 500-700 nm. This is in contrast to high-concentration Bi doping of 1% and 2%. 3+The crystal, with a low doping concentration of 0.6%, exhibits a strong emission peak in the 460-490 nm range, with a bandwidth of 30 nm, precisely in the cyan band, indicating that the crystal sample can effectively emit cyan afterglow. Meanwhile, the Bi doping concentration cannot be too high. Observation reveals that when the doping concentration is too high, such as 1% or 2% high-concentration Bi doping... 3+ The crystal no longer emits cyan light, but rather a weaker orange-red spectrum.

[0076] Figure 5 The emission spectra (visible light band) of samples 1 and 5-6 were measured at 312 nm. It can be seen that at 312 nm excitation and with the same doping concentration... Under these conditions, the emission peaks in the emission spectra of samples 0.6% Bi 0.1% Nd and 0.6% Bi 0.2% Nd correspond to the same wavelengths. All three samples (0.6% Bi, 0.6% Bi 0.1% Nd, and 0.6% Bi 0.2% Nd) exhibit a main emission peak at 466 nm, with smaller emission peaks also appearing between 500-600 nm. Furthermore, when 0.6%... In ion doping concentration With the increasing proportion of [a specific component], the signal intensity of the 466nm emission peak showed a trend of first increasing and then decreasing. This is because of the increasing proportion of [a specific component]. It can act as an impurity energy level to broaden the light absorption range, allowing it to effectively absorb energy in the crystal and emit it in the form of blue-green light, resulting in stronger blue-green light emission. In embodiments of the present invention, The optimal doping concentration for emission intensity.

[0077] Figure 6 The images show the emission spectra (near-infrared band) of samples 1 and 5-6 under 585nm detection. It can be seen that, compared to single-doped crystals, double-doped crystals exhibit two main emission peaks in the infrared band, at 885nm and 1072nm, and a secondary emission peak at 1342nm. Compared to single-doped crystals... The crystal material, especially the double-doped crystal material, has an advantage in the near-infrared band and the emission peak is a characteristic peak, so it can be used as a multi-layer anti-counterfeiting material.

[0078] Figure 7 The images show a comparison of samples 1-7 observed under sunlight and after irradiation with 254nm ultraviolet light in a dark room. It can be seen that the single-doped and double-doped crystals are white under sunlight, but exhibit cyan fluorescence after irradiation with 254nm ultraviolet light. Furthermore, it can be observed that when... When the doping concentration is increased to 0.1%, its cyan fluorescence and color are clearly visible compared to crystals with other doping concentrations. Furthermore, after irradiating the crystal with 254nm ultraviolet light for five minutes and then removing the ultraviolet light source, a cyan afterglow phenomenon appears. This is consistent with the emission spectrum detected at 312nm, which in real life manifests as brighter fluorescence and a deeper fluorescence color.

[0079] Figure 8 The PL spectra of samples 5 and 8 under 312 nm excitation are shown. It can be seen that the dual-doped crystals prepared by different methods all exhibit a strong main emission peak at 450 nm within the 350-700 nm range, demonstrating excellent monochromaticity and making them suitable as the blue emission center for novel light-emitting diodes. Meanwhile, the dual-doped crystal (sample 5) prepared using the optimized high-temperature solid-state method not only significantly reduces the procedures and time required for traditional reactions, but also achieves a maximum intensity (taking 450 nm as an example) that is approximately 21.6% stronger than that prepared by the unoptimized method, resulting in vivid color, high recognition, and high brightness in practical applications.

[0080] As can be seen from the above tests, this embodiment synthesizes... The crystal's emission spectrum was measured using a fluorescence spectrometer, and it was found that... It can enhance blue-green light emission in the visible light band while also exhibiting near-infrared luminescence in the near-infrared band. When the crystal is irradiated with 254nm ultraviolet light for five minutes, and then the ultraviolet light source is removed, a cyan afterglow phenomenon occurs. Co-doped crystals produce the best blue afterglow effect.

[0081] Those skilled in the art will readily understand that the above description is merely an embodiment of the present invention and is not intended to limit the present invention. 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 present invention.

Claims

1. A multi-band luminescent perovskite afterglow material, characterized in that, by As the matrix material, with bismuth and neodymium ions as dopant ions, the expression is: The value of x ranges from 0.5 to 0.7, and the value of y ranges from 0.05 to 0.

4.

2. The multi-band luminescent perovskite afterglow material according to claim 1, characterized in that, The value of y ranges from 0.1 to 0.

2.

3. The multi-band luminescent perovskite afterglow material according to claim 1, characterized in that, The expression is .

4. The method for preparing the multi-band luminescent perovskite afterglow material according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1: Weigh calcium carbonate, tin dioxide, bismuth source, and neodymium source according to the expression; S2: Grind the raw material obtained by weighing in step S1 thoroughly; S3: The powder ground in step S2 undergoes a high-temperature solid-phase reaction in a high-temperature heating device; S4: Cooling annealing yields multi-band luminescent perovskite afterglow material.

5. The preparation method according to claim 4, characterized in that, Step S2 involves thoroughly grinding the raw material obtained by weighing in step S1, specifically as follows: Add the raw material weighed in step S1 to the grinding media and grind it thoroughly with the grinding media rod for 25-30 minutes.

6. The preparation method according to claim 4, characterized in that, The bismuth source is bismuth trioxide, and the neodymium source is neodymium trioxide.

7. The preparation method according to claim 4, characterized in that, The powder after grinding described in step S3 undergoes a high-temperature solid-phase reaction in a high-temperature heating device, specifically as follows: The ground powder is placed in an alumina crucible and then placed in a high-temperature heating device for a high-temperature solid-phase reaction; the high-temperature heating device is a muffle furnace with a built-in muffle furnace door plug.

8. The preparation method according to claim 4, characterized in that, In the high-temperature solid-state reaction, the heating process is as follows: heating from room temperature to 880~920℃ for 175~185 minutes; then holding at 880~920℃ for 115~125 minutes; continuing to heat from 880~920℃ to 1380~1420℃ for 115~125 minutes; and then holding at 1380~1420℃ for 175~185 minutes.

9. The preparation method according to claim 4, characterized in that, The cooling annealing described in step S4 specifically involves natural cooling within the muffle furnace.

10. A luminescent perovskite afterglow material, characterized in that, by As the matrix material, with bismuth ions as dopant ions, the expression is: , where x ranges from 0.5 to 0.7.

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