A perovskite nanocrystalline chalcogenide glass with high optical limiting performance and its preparation method

Abstract

The high-performance perovskite nanocrystal chalcogenide glass disclosed in this invention is a GeS glass inlaid with CsSnBr3 perovskite nanocrystals. 1.5 Chalcogenide glass composites, the precursor glass of the composite has a molar composition of 95 GeS. 1.5 -5 (CsBr-SnBr2) is a composite material containing CsSnBr3 perovskite nanocrystals with a grain size of 10–80 nm. It is obtained by microcrystallizing a precursor glass at 285–295 °C for 5–20 h. This perovskite nanocrystal chalcogenide glass composite material is free of lead and antimony, two toxic heavy metals, and possesses advantages such as high transmittance, high mechanical strength, strong nonlinear absorption, and excellent optical limiting performance. Its infrared optical transmittance is between 60–80%, and its Vickers hardness can reach up to 279 kg / mm². 2 The maximum nonlinear absorption coefficient is 23.91 cm / GW, and the minimum optical limiting threshold is 45.2 μJ / cm. 2 It is an excellent material for fabricating high-performance optical limiting devices.

Description

Technical Field

[0001] This invention relates to the technical field of nanocrystalline composite glasses with high optical nonlinearity, specifically a perovskite nanocrystalline chalcogenide glass with high optical limiting performance and its preparation method. Background Technology

[0002] The exceptional linear optical properties of metal halide perovskites (hereinafter referred to as perovskites) have garnered widespread attention over the past decade, leading to their successful applications in solar cells, light-emitting diodes (LEDs), and photodetectors. In recent years, with the deepening of perovskite research, the material's excellent nonlinear optical properties (including high nonlinear refractive index, large photon absorption cross section, and strong saturation absorption) have also attracted considerable attention from researchers, resulting in a proliferation of high-performance nonlinear photonic devices based on perovskites. However, perovskites are unstable, especially when exposed to high-power-density lasers—a condition essential for generating nonlinear optical effects. This inherent instability poses a significant challenge to the practical application of perovskites in nonlinear photonics.

[0003] An effective solution to the instability of perovskites is to encapsulate them in stable and transparent optical glass, giving them resistance to light, heat, moisture, and mechanical shock. Among various optical glasses, chalcogenides are a novel glass system with infrared transmission and high nonlinear optical properties, and they are considered a platform for next-generation high-performance infrared and nonlinear photonic devices. Furthermore, chalcogenides have excellent compatibility with perovskites, which are metal halides; therefore, the combination of the two—perovskite nanocrystal composite chalcogenides—can combine the nonlinear optical properties of both materials, resulting in even better nonlinear optical performance. Recently, the applicant discovered for the first time the ultra-strong nonlinear absorption properties of perovskite nanocrystal composite chalcogenides, making it an excellent light-limiting material that can be used to protect the human eye and optical sensing devices from laser damage. To address the issues of antimony (a toxic heavy metal) in the matrix glass and lead (a toxic heavy metal) in the perovskite nanocrystalline composite chalcogenide glass, this invention improves the composition of the matrix glass and perovskite in the composite material, proposing a novel perovskite nanocrystalline chalcogenide glass material that is more environmentally friendly and has ultra-high optical limiting performance, as well as its preparation method. Summary of the Invention

[0004] In view of the fact that existing perovskite nanocrystalline composite chalcogenide glasses generally contain toxic heavy metal elements and their compositions are not optimized for their nonlinear absorption characteristics, this invention provides a non-toxic, environmentally friendly perovskite nanocrystalline chalcogenide glass with high optical limiting performance and its preparation method. This nanocrystalline chalcogenide glass does not contain the toxic heavy metal elements lead and antimony and has advantages such as good chemical and thermal stability, high transmittance, high mechanical strength, strong nonlinear absorption, excellent optical limiting performance, and ease of machining. Its infrared optical transmittance is between 60% and 80%, and its Vickers hardness can reach up to 279 kg / mm². 2 The maximum nonlinear absorption coefficient is 23.91 cm / GW, and the minimum optical limiting threshold is 45.2 μJ / cm. 2 It is an excellent material for fabricating high-performance optical limiting devices.

[0005] The technical solution adopted by this invention to solve the above-mentioned technical problems is: a perovskite nanocrystal chalcogenide glass with high optical limiting performance, wherein the nanocrystal chalcogenide glass is a GeS glass with CsSnBr3 perovskite nanocrystals embedded in it. 1.5 Chalcogenide glass composite material, wherein the precursor glass of the composite material has a molar composition of 95 GeS. 1.5 -5(CsBr-SnBr2), the composite material contains CsSnBr3 perovskite nanocrystals with a grain size of 10-80 nm, and the composite material is obtained by microcrystallization treatment of the precursor glass at a temperature of 285-295℃ for 5-20 h.

[0006] In one preferred embodiment, the microcrystallization treatment temperature is 290°C. The average size of the perovskite nanocrystals contained in the composite material after microcrystallization treatment at this temperature is approximately 40 nm. Testing showed that the maximum nonlinear absorption coefficient of this nanocrystalline chalcogenide glass is 23.91 cm / GW, which is higher than that of the matrix chalcogenide glass GeS0. 1.5 It has twice the nonlinear absorption coefficient, and its minimum optical limiting threshold is 45.2 μJ / cm. 2 This demonstrates excellent nonlinear absorption characteristics, making it suitable for the manufacture of optical limiting devices.

[0007] A method for preparing a perovskite nanocrystal chalcogenide glass with high optical limiting performance includes the following steps:

[0008] S1, Raw material preparation and vacuum packaging

[0009] Based on the molar composition of the precursor glass: 95GeS 1.5-5(CsBr-SnBr2), first calculate the required amount of each raw material. Weigh the high-purity germanium, sulfur, cesium bromide, and stannous bromide raw materials using an electronic balance, controlling the error within ±0.001g. Then, load all raw materials into a dry and clean quartz tube and evacuate the quartz tube to 10°C. -4 Below Pa, the raw material is encapsulated in a quartz tube;

[0010] S2, Raw material melting and mixing

[0011] The quartz tube containing the raw material was placed in a swing furnace for high-temperature melting at a temperature of 900°C for 12 hours. After melting, the quartz tube was removed from the swing furnace and then quickly immersed in water at room temperature to quench the molten material. After observing the wall separation, it was immediately removed, and a semi-finished precursor glass was obtained inside the quartz tube.

[0012] S3, Annealing for stress relief

[0013] The semi-finished precursor glass, together with the quartz tube, is annealed at a temperature of 255–265°C for 10–14 hours. After annealing, the temperature is lowered to room temperature at a rate of 9–10°C / hour. The quartz tube is then removed from the annealing furnace and opened to obtain the finished precursor glass.

[0014] S4, Microcrystallization treatment

[0015] The precursor glass is microcrystallized at a temperature of 285–295°C for 5–20 h to obtain a perovskite nanocrystal chalcogenide glass with high light limiting performance, which contains CsSnBr3 nanocrystals with a size in the range of 10–80 nm.

[0016] In a preferred embodiment, the temperature of the microcrystallization treatment in step S4 is 290°C.

[0017] Compared with the prior art, the perovskite nanocrystal chalcogenide glass of the present invention has the following advantages:

[0018] 1. It does not contain lead or antimony, two toxic heavy metals, and is environmentally friendly;

[0019] 2. The size and quantity of CsSnBr3 perovskite nanocrystals in the composite material can be flexibly adjusted according to the heat treatment time and temperature, thereby enabling the control of the corresponding performance parameters;

[0020] 3. It exhibits good chemical and thermal stability, high transmittance, high mechanical strength, strong nonlinear absorption, excellent light limiting performance, and ease of machining. It possesses high mechanical strength, high transparency, and a high nonlinear absorption coefficient. Testing revealed that the Vickers hardness of the nanocrystalline composite chalcogenide glass material obtained by this invention can reach up to 279 kg / mm².2 Light transmittance can reach 60-80%, and the maximum nonlinear absorption coefficient is 23.91 cm / GW;

[0021] 4. It exhibits extremely high light limiting performance. Tests have shown that the light limiting threshold of the composite material obtained by this invention can reach as low as 45.2 μJ / cm. 2 It is an excellent material for fabricating high-performance optical limiting devices. Attached Figure Description

[0022] Figure 1 A schematic diagram of the experimental setup used in the Z-scan experiment;

[0023] Figure 2 The nonlinear absorption curves of the material samples of the blank group, comparative example 1, and examples 1 to 4 at the same light wavelength (750 nm) are shown in the figure. The numbers ① to ⑥ in the figure correspond to the blank group, comparative example 1, and examples 1 to 4, respectively.

[0024] Figure 3 The figure shows the Z-scan curves of the composite material sample of Example 4 at different optical wavelengths (750-900nm). The numbers ① to ④ in the figure correspond to optical wavelengths of 750, 800, 850 and 900nm, respectively.

[0025] Figure 4 Transmission spectra of the material samples from the blank group, comparative example 1, and examples 1-4 at different optical wavelengths (440-2000 nm);

[0026] Figure 5 XRD patterns of material samples from the blank group, comparative example 1, and examples 1-4;

[0027] Figure 6 The transmission electron microscope (TEM) image of the composite material sample from Example 4;

[0028] Figure 7 The image shows the optical limiting spectrum of the composite material sample in Example 4. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0030] Examples 1-4 describe high-performance perovskite nanocrystalline chalcogenide glasses, which are GeS2 nanocrystalline chalcogenide glasses inlaid with CsSnBr3 perovskite nanocrystals. 1.5 Chalcogenide glass composite material, wherein the precursor glass of the composite material has a molar composition of 95 GeS. 1.5-5(CsBr-SnBr2) The composite material contains CsSnBr3 perovskite nanocrystals with a grain size of 10-80 nm. The composite material is obtained by microcrystallization treatment of precursor glass at a temperature of 285-295℃ for 5-20 h.

[0031] The preparation method of high-performance perovskite nanocrystal chalcogenide glasses in Examples 1-4 specifically includes the following steps:

[0032] S1, Raw material preparation and vacuum packaging

[0033] Based on the molar composition of the precursor glass: 95GeS 1.5 -5(CsBr-SnBr2), first calculate the required amount of each raw material. Weigh the high-purity germanium (99.999%, 5N), sulfur (5N), cesium bromide (4N), and stannous bromide (4N) raw materials using an electronic balance, controlling the error within ±0.001g. Then, load all raw materials into a dry and clean quartz tube and evacuate the quartz tube to 10°C. -4 Below Pa, the raw material is encapsulated in a quartz tube;

[0034] S2, Raw material melting and mixing

[0035] The quartz tube containing the raw material was placed in a swing furnace for high-temperature melting at a temperature of 900°C for 12 hours. After melting, the quartz tube was removed from the swing furnace and then quickly immersed in water at room temperature to quench the molten material. After observing the wall separation, it was immediately removed, and a semi-finished precursor glass was obtained inside the quartz tube.

[0036] S3, Annealing for stress relief

[0037] The semi-finished precursor glass, along with the quartz tube, is annealed at a temperature of 255–265°C (about 30°C lower than the glass transition temperature) for 10–14 hours to eliminate internal stress in the glass material. After annealing, the temperature is lowered to room temperature at a rate of 9–10°C / hour. The quartz tube is then removed from the annealing furnace, opened, and the finished precursor glass is obtained.

[0038] S4, Microcrystallization treatment

[0039] The precursor glass was microcrystallized at 285–295 °C for 5–20 h to obtain GeS2 containing CsSnBr3 perovskite nanocrystals. 1.5 Chalcogenide glass composites, namely perovskite nanocrystal chalcogenide glasses with high light limiting performance, contain CsSnBr3 nanocrystals with sizes ranging from 10 to 80 nm.

[0040] The preparation methods of the high-brightness limiting perovskite nanocrystalline chalcogenide glasses in each embodiment differ only in the microcrystallization treatment time; all other steps and parameters are the same. Specifically, the microcrystallization treatment times in Examples 1-4 are 5h, 10h, 15h, and 20h, respectively.

[0041] For comparison, glass from the blank group and Comparative Example 1 were selected. The difference from Example 1 is that the glass in the blank group was a GeS matrix glass. 1.5 No raw materials for synthesizing CsSnBr3 perovskite were added; the heat treatment time of the glass in Comparative Example 1 was 0 h, that is, no microcrystallization treatment was performed on the glass, and no perovskite crystals were precipitated in the glass.

[0042] For the sake of simplicity, Figure 2 , Figure 4 , Figure 5 In the examples, GSS, GSSC-0h, GSSC-5h, GSSC-10h, GSSC-15h, and GSSC-20h represent the material samples of the blank group, comparative example 1, example 1, example 2, example 3, and example 4, respectively.

[0043] Table 1 lists the mechanical and optical property parameters of the material samples from the blank group, Comparative Example 1, and Examples 1-4, where H v Represents Vickers hardness, λ s E represents the shortwave absorption cutoff edge. opg The value represents the optical band gap energy. Table 1 shows that the Vickers hardness value of Comparative Example 1 is higher than that of the blank group, indicating that the introduction of the perovskite precursor can enhance the mechanical properties of the glass. The hardness values ​​of Examples 1 to 4 are all higher than those of Comparative Example 1, indicating that the perovskite nanocrystals precipitated after microcrystallization treatment can improve the overall structure of the glass micro-network and further improve the overall mechanical strength of the composite material.

[0044] Table 1: Mechanical and optical properties of glass samples

[0045]

[0046] For all samples, an open-aperture Z-scan experiment was used to determine their nonlinear absorption coefficients. The four selected wavelengths were 750 nm, 800 nm, 850 nm, and 900 nm. The experimental setup is as follows: Figure 1As shown. The laser source was a Ti:sapphire femtosecond laser (Chameleon Ultra II, USA), with an adjustable excitation range of 680–1080 nm, a repetition rate of 80 MHz, a pulse width of 140 fs, and a power stability of ±3%. The laser beam first passed through a highly reflective mirror and was then split into two beams by a semi-transparent beam splitter (45% reflectivity and 55% transmittance). One beam served as a reference source for the incident power and was detected by power detector 1. The other beam was focused by a biconvex mirror and irradiated onto the glass sample. The transmitted beam was received by optical power detector 2. The power signals received by power detectors 1 and 2 were input to a Coherent EM2000 dual-channel power meter. During the experiment, the sample position was adjusted using a stepper motor controller, and the power meter readings were recorded to obtain a set of Z-scan data corresponding to the sample position and transmitted power. All tests were conducted at room temperature.

[0047] The Z-scan experimental curves of the glass samples from the blank group, Comparative Example 1, and Examples 1-4 at a wavelength of 900 nm are shown below. Figure 2 .from Figure 2 It can be seen that the valley depth (normalized transmittance difference ΔT) of the composite materials in each embodiment is... v Compared to the blank group and Comparative Example 1, the perovskite crystal precipitation showed a significant decreasing trend, indicating that the precipitation of perovskite crystals can significantly enhance the overall nonlinear absorption characteristics of the composite material. Figure 3 The Z-scan curves of the composite material sample from Example 4 at different optical wavelengths (750–900 nm) show that the ΔT of the sample increases with increasing wavelength. v The decrease in the nonlinear coefficient indicates that the nonlinear absorption characteristics of the composite material exhibit positive dispersion.

[0048] Table 2 lists the nonlinear absorption coefficient β of each sample at different wavelengths. The nonlinear absorption coefficient β of the blank group sample at a wavelength of 900 nm is 0.09 cm / GW, which is the minimum value. Example 4 at a wavelength of 750 nm has the largest nonlinear absorption coefficient β, which is 23.91 cm / GW.

[0049] Table 3 lists the optical limiting threshold (OTL) for each sample at different wavelengths. The OTL for the blank group samples at a wavelength of 900 nm is 407.9 μJ / cm. 2 The maximum value is 45.2 cμJ / cm², which is the smallest optical limiting threshold (OTL) in Example 4 at a wavelength of 750 nm. 2 .

[0050] Regarding the composite material sample in Example 4, the presence of nanoscale perovskite crystals in the matrix glass generates new valence states between the valence and conduction bands of the glass. This enhances its ability to absorb photons with energy below the band gap, thereby enabling electron transitions between band gaps and increasing the intensity of multiphoton absorption. As shown in Table 2, the photon energy at 750 nm and the defect states in the nanocrystalline glass sample exhibit a better resonance effect at the focal point, enhancing nonlinear absorption. Therefore, compared to other wavelengths, under 750 nm laser radiation, the normalized transmittance difference ΔT of the sample increases with increasing microcrystallization time. v The crystallinity increases significantly, exhibiting a stronger nonlinear absorption effect. Furthermore, overall analysis reveals that the quantum effect of perovskite nanocrystals—specifically, the perovskite nanoparticles confined within the glass matrix causing the valence and conduction bands to decompose into a series of discrete energy levels—leads to an increase in nonlinear characteristics with increasing crystallinity at the incident wavelength. Through changes in the quantum states and interactions of electrons in the light field, the intraband transitions of electrons in the glass matrix increase, resulting in changes in nonlinear absorption. Based on the variation of nonlinear absorption with light intensity, we can measure the optical limiting threshold of the sample to assess its optical limiting capability. Ultimately, we obtained a perovskite nanocrystal composite chalcogenide glass with the smallest optical limiting threshold.

[0051] Table 2: Nonlinear absorption coefficients of glass samples

[0052]

[0053] Table 3: Light limiting threshold of glass samples

[0054]

[0055] Figure 4 The transmission spectra of the blank group, Comparative Example 1, and material samples from Examples 1-4 are shown in different optical wavelengths (440-2000 nm). Figure 4 It is evident that, in the broad region from near-infrared to mid-infrared, the composite material, like the matrix glass, exhibits high optical transparency. Figure 5 The XRD patterns of the blank group, comparative example 1, and material samples from Examples 1-4 are shown. Figure 5 It can be seen that after 20 hours of microcrystallization treatment, clearly distinguishable crystal diffraction peaks appeared in the spectrum. Figure 5 (As indicated by the 5 arrows in the image), comparing it with the PDF card confirms that it is a CsSnBr3 crystal. Figure 6 Transmission electron microscopy (TEM) images of the composite material sample from Example 4 are shown, revealing spherical nanocrystals within the glass matrix. Figures 5-6 It can be seen that the changes in the internal crystal structure of glass over time can be summarized as follows:

[0056] (1) For the blank group and comparative example 1, simply by... Figure 5 The XRD pattern shows that the glass is homogeneous inside with no crystals.

[0057] (2) For Examples 1 to 3, according to Figure 5 The XRD pattern shows the presence of tiny crystal diffraction peaks. At this point, the crystal aggregation is small, so the diffraction peaks are not obvious.

[0058] (3) For Example 4, the microcrystallization treatment time reached 20 hours. According to Ostwald's ripening theory, the nanocrystals inside the glass further aggregated, and the crystal size further increased. Figure 5 The XRD pattern indicates that the crystal growth is mature and can achieve effective diffraction on each crystal plane, specifically manifested by the presence of resolvable crystal diffraction peaks in its XRD pattern. Combined with the PDF card and... Figure 6 TEM image analysis confirmed that the crystals at this time were CsSnBr3 nanocrystals.

[0059] Figure 7 The image shows the optical limiting spectrum of the composite material sample in Example 4 at a wavelength of 750 nm. It can be seen that the normalized transmittance of the sample decreases with increasing laser input intensity, reflecting its optical limiting characteristics. The laser input intensity at which the normalized transmittance drops to 0.5 is defined as the optical limiting threshold (OLT), and its fitted value is 45.2 μJ / cm². 2 .

Claims

1. A perovskite nanocrystalline chalcogenide glass with high light limiting performance, characterized in that, This nanocrystalline chalcogenide glass is a GeS2O3 glass inlaid with CsSnBr3 perovskite nanocrystals. 1.5 Chalcogenide glass composite material, wherein the precursor glass of the composite material has a molar composition of 95 GeS. 1.5 -5(CsBr-SnBr2), the composite material contains CsSnBr3 perovskite nanocrystals with a grain size of 10-80 nm, and the composite material is obtained by microcrystallization treatment of the precursor glass at a temperature of 285-295℃ for 5-20 h.

2. The high-performance perovskite nanocrystalline chalcogenide glass according to claim 1, characterized in that, The temperature for the microcrystallization treatment is 290°C.

3. The high-performance perovskite nanocrystalline chalcogenide glass according to claim 1, characterized in that, The minimum optical limiting threshold of this nanocrystalline chalcogenide glass is 45.2 μJ / cm. 2 .

4. The method for preparing the high-performance perovskite nanocrystalline chalcogenide glass according to claim 1, characterized in that, Includes the following steps: S1, Raw material preparation and vacuum packaging Based on the molar composition of the precursor glass: 95GeS 1.5 -5(CsBr-SnBr2), first calculate the required amount of each raw material. Weigh the high-purity germanium, sulfur, cesium bromide, and stannous bromide raw materials using an electronic balance, controlling the error within ±0.001g. Then, load all raw materials into a dry and clean quartz tube and evacuate the quartz tube to 10°C. -4 Below Pa, the raw material is encapsulated in a quartz tube; S2, Raw material melting and mixing The quartz tube containing the raw material was placed in a swing furnace for high-temperature melting at a temperature of 900°C for 12 hours. After melting, the quartz tube was removed from the swing furnace and then quickly immersed in water at room temperature to quench the molten material. After observing the wall separation, it was immediately removed, and a semi-finished precursor glass was obtained inside the quartz tube. S3, Annealing for stress relief The semi-finished precursor glass, together with the quartz tube, is annealed at a temperature of 255–265°C for 10–14 hours. After annealing, the temperature is lowered to room temperature at a rate of 9–10°C / hour. The quartz tube is then removed from the annealing furnace and opened to obtain the finished precursor glass. S4, Microcrystallization treatment The precursor glass is microcrystallized at a temperature of 285–295°C for 5–20 h to obtain a perovskite nanocrystal chalcogenide glass with high light limiting performance, which contains CsSnBr3 nanocrystals with a size in the range of 10–80 nm.

5. The method for preparing high-performance perovskite nanocrystalline chalcogenide glass according to claim 4, characterized in that, In step S4, the temperature of the microcrystallization treatment is 290°C.

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