A heterojunction stress-luminescent material, its preparation method and application

Abstract

This invention relates to the field of heterojunction technology, and in particular to a heterojunction stress-luminescent material, its preparation method, and its applications. The chemical formula of the heterojunction stress-luminescent material is Ca3(PO4)2 / Ca5(PO4)3OH:Eu. 2+ Eu 3+ Among them, Eu 2+ With Eu 3+ The molar ratio is 0.1-10:1. The heterojunction stress-luminescent material provided by this invention has an extremely wide ML emission spectrum (400nm-700nm) and excellent luminescence stability, which can be better adapted to spectral detectors and imaging sensors.

Description

Technical Field

[0001] This invention relates to the field of heterojunction technology, and in particular to a heterojunction stress luminescent material, its preparation method, and its application. Background Technology

[0002] Currently, there are not many types of heterojunction stress-luminescent materials, with sulfate and niobate heterojunctions being relatively more common. For example, sulfide-based ZnS / CaZnOS heterostructures significantly enhance stress luminescence by utilizing interfacial band shifts to improve carrier separation and recombination efficiency. Peng et al. reported a ZnS / CaZnOS:Mn 2+ Heterojunctions, with optimized interfacial charge transfer, exhibit a 2.2-fold increase in mechanoluminescence (ML) intensity compared to conventional zinc sulfide. Yanmin Yang et al. reported a ZnF2 / ZnO heterostructure and revealed the underlying mechanism for enhanced mechanoluminescence (ML) through density functional theory (DFT) calculations. Niobate heterostructures, such as LiNbO3 and KNbO3, can generate strong electric fields under mechanical stress due to their inherent piezoelectric properties. These electric fields enhance carrier excitation and recombination, thereby effectively activating luminescence. For example, Dong Tu et al. demonstrated that Li... 1-x Na X NbO3:Pr 3+ Heterogeneous structures provide a new strategy for developing high-brightness mechanoluminescence.

[0003] Due to the limited variety and difficulty in discovering heterojunction stress-luminescent materials, the following drawbacks exist: 1. Insufficient stability and durability; high stress concentration may lead to interface failure (such as fatigue cracks in array structure devices under cyclic loading). 2. Insufficient spectral width. The relatively narrow spectral output places stringent requirements on detection instruments, particularly regarding spectral matching and compatibility with wavelength-specific imaging sensors and photoelectric detection modules. Summary of the Invention

[0004] The purpose of this invention is to provide a heterojunction stress-luminescent material, its preparation method, and its applications, thereby overcoming the shortcomings of existing heterojunction stress-luminescent materials, such as narrow spectral width and poor stability.

[0005] To achieve the above objectives, the present invention provides a heterojunction stress-luminescent material with the chemical formula Ca3(PO4)2 / Ca5(PO4)3OH:Eu 2+ Eu 3+ ;

[0006] Among them, Eu 2+ With Eu 3+ The molar ratio is 0.1-10:1.

[0007] This invention also provides a method for preparing the above-mentioned heterojunction stress-luminescent material, comprising the following preparation steps:

[0008] S1. Mix CaCO3, NH4H2PO4 and Eu2O3, grind and dry to obtain a mixture;

[0009] S2. The heterojunction stress luminescent material is obtained by sintering the mixture under a mixed atmosphere.

[0010] In some embodiments of the present invention, the mass ratio of CaCO3, NH4H2PO4 and Eu2O3 in S1 is 0.9-1:0.6-0.7:0.001-0.015.

[0011] In some embodiments of the present invention, the grinding time in S1 is 5-10 min.

[0012] In some embodiments of the present invention, the drying temperature in S1 is 60-80°C and the drying time is 10-20 min.

[0013] In some embodiments of the present invention, the mixed atmosphere in S2 includes nitrogen and hydrogen, with a volume ratio of nitrogen to hydrogen of 85-90:10-15.

[0014] In some embodiments of the present invention, the sintering temperature in S2 is 1300-1400°C, and the sintering time is 0.5-5h.

[0015] The present invention also provides the application of the above-mentioned heterojunction stress luminescent material in spectral detectors and imaging sensors.

[0016] The present invention has the following beneficial effects

[0017] This invention provides a heterojunction stress-luminescent material with the chemical formula Ca3(PO4)2 / Ca5(PO4)3OH:Eu 2+ Eu 3+ Its stress luminescence intensity is 2.3 times higher than that of the original Ca3(PO4)2 and Ca5(PO4)3OH. The heterojunction stress luminescent material provided by this invention has an extremely wide ML emission spectrum (400nm-700nm) and excellent luminescence stability, making it more suitable for spectral detectors and imaging sensors.

[0018] This invention clarifies the Ca3(PO4)2 / Ca5(PO4)3OH:Eu 2+ Eu 3+ The ML mechanism is a triboelectric-induced trap-controlled mechanism.

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Figure 1 This is the XRD pattern of the heterojunction stress-luminescent material prepared in Example 1 of this invention;

[0021] Figure 2 This is an XPS image of the heterojunction stress-luminescent material prepared in Example 1 of this invention;

[0022] Figure 3 This is a TEM image of the heterojunction stress-luminescent material prepared in Comparative Example 1 of this invention;

[0023] Figure 4 This is a comparison of the spectral intensities of the heterojunction stress luminescent material prepared in Example 1 of this invention and the Ca3(PO4)2 and Ca5(PO4)3OH materials;

[0024] Figure 5 This is a comparison of the spectral intensities of the heterojunction stress-luminescent materials prepared in Example 1 and Comparative Example 1 of the present invention;

[0025] Figure 6 This is a stability test diagram of the heterojunction stress luminescent material prepared in Example 1 of the present invention. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should be understood in their ordinary sense by those skilled in the art. The features mentioned above or in the specific examples mentioned in this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the invention and are not intended to limit the scope of the invention.

[0027] The Ca3(PO4)2 used in the following examples was purchased from Aladdin (C111984). ， NH4H2PO4 was purchased from Aladdin (A111768), and Eu2O3 was purchased from Aladdin (E106503).

[0028] Example 1

[0029] This embodiment provides a heterojunction stress-luminescent material with the chemical formula Ca3(PO4)2 / Ca5(PO4)3OH:Eu 2+ Eu 3+ ;

[0030] Among them, Eu 2+ With Eu 3+ The molar ratio is 2.5:1.

[0031] The preparation method of the above-mentioned heterojunction stress-luminescent material includes the following steps:

[0032] S1. Mix 0.9939g of CaCO3, 0.6902g of NH4H2PO4 and 0.0123g of Eu2O3, grind for 5min, and then dry at 70℃ for 10min to obtain the mixture.

[0033] S2. Under a mixed atmosphere of nitrogen and hydrogen (volume ratio of nitrogen to hydrogen is 90:10), the mixture is sintered at 1350°C for 3 hours to obtain the above-mentioned heterojunction stress luminescent material.

[0034] Example 2

[0035] This embodiment provides a heterojunction stress-luminescent material with the chemical formula Ca3(PO4)2 / Ca5(PO4)3OH:Eu 2+ Eu 3+ ;

[0036] Among them, Eu 2+ With Eu 3+ The molar ratio is 1:1.

[0037] The preparation method of the above-mentioned heterojunction stress-luminescent material includes the following steps:

[0038] S1. Mix 0.9999g of CaCO3, 0.6902g of NH4H2PO4 and 0.0018g of Eu2O3, grind for 10min, and then dry at 60℃ for 15min to obtain the mixture.

[0039] S2. Under a mixed atmosphere of nitrogen and hydrogen (volume ratio of nitrogen to hydrogen is 90:10), the mixture is sintered at 1300°C for 1 hour to obtain the above-mentioned heterojunction stress luminescent material.

[0040] Example 3

[0041] This embodiment provides a heterojunction stress-luminescent material with the chemical formula Ca3(PO4)2 / Ca5(PO4)3OH:Eu 2+ Eu 3+ ;

[0042] Among them, Eu 2+ With Eu 3+ The molar ratio is 8:1.

[0043] The preparation method of the above-mentioned heterojunction stress-luminescent material includes the following steps:

[0044] S1. Mix 0.9969g of CaCO3, 0.6902g of NH4H2PO4 and 0.0070g of Eu2O3, grind for 8min, and then dry at 70℃ for 15min to obtain the mixture.

[0045] S2. Under a mixed atmosphere of nitrogen and hydrogen (volume ratio of nitrogen to hydrogen is 90:10), the mixture is sintered at 1400℃ for 3.5h to obtain the above-mentioned heterojunction stress luminescent material.

[0046] Example 4

[0047] This embodiment provides a heterojunction stress-luminescent material with the chemical formula Ca3(PO4)2 / Ca5(PO4)3OH:Eu 2+ Eu 3+ ;

[0048] Among them, Eu 2+ With Eu 3+ The molar ratio is 10:1.

[0049] The preparation method of the above-mentioned heterojunction stress-luminescent material includes the following steps:

[0050] S1. Mix 0.9969g of CaCO3, 0.6902g of NH4H2PO4 and 0.0070g of Eu2O3, grind for 8min, and then dry at 80℃ for 10min to obtain the mixture.

[0051] S2. Under a mixed atmosphere of nitrogen and hydrogen (volume ratio of nitrogen to hydrogen is 90:10), the mixture is sintered at 1400℃ for 5 hours to obtain the above-mentioned heterojunction stress luminescent material.

[0052] Example 5

[0053] This embodiment provides a heterojunction stress-luminescent material with the chemical formula Ca3(PO4)2 / Ca5(PO4)3OH:Eu 2+ Eu 3+ ;

[0054] Among them, Eu 2+ With Eu 3+ The molar ratio is 0.1:1.

[0055] The preparation method of the above-mentioned heterojunction stress-luminescent material includes the following steps:

[0056] S1. Mix 0.9969g of CaCO3, 0.6902g of NH4H2PO4 and 0.0070g of Eu2O3, grind for 8min, and then dry at 65℃ for 20min to obtain the mixture.

[0057] S2. Under a mixed atmosphere of nitrogen and hydrogen (volume ratio of nitrogen to hydrogen is 90:10), the mixture is sintered at 1300℃ for 0.5h to obtain the above-mentioned heterojunction stress luminescent material.

[0058] Comparative Example 1

[0059] This comparative example provides a heterojunction stress-luminescent material with the chemical formula Ca3(PO4)2 / Ca5(PO4)3OH:3.5%Eu. 3+ .

[0060] The preparation method of the above-mentioned heterojunction stress-luminescent material includes the following steps:

[0061] S1. Mix 0.9939g of CaCO3, 0.6902g of NH4H2PO4 and 0.0123g of Eu2O3, grind for 5min, and then dry at 70℃ for 10min to obtain the mixture.

[0062] S2. The mixture is sintered at 1350°C for 3 hours in an air atmosphere to obtain the above-mentioned heterojunction stress luminescent material.

[0063] Characterization detection

[0064] The heterojunction stress-luminescent material prepared in Example 1 was subjected to X-ray diffraction analysis, and its XRD pattern is shown below. Figure 1 As shown. According to Figure 1 As can be seen from the comparison of Ca3(PO4)2 (PDF#09-0169) and Ca5(PO4)3OH (PDF#84-1998), the heterojunction stress luminescent material prepared in this invention has a Ca3(PO4)2 / Ca5(PO4)3OH dual phase.

[0065] The heterojunction stress-luminescent material prepared in Example 1 was subjected to photoelectron energy analysis, and its XPS plot is shown below. Figure 2 As shown. From Figure 2 It can be seen that the heterojunction stress-luminescent material prepared in Example 1 simultaneously possesses Eu 2+ and Eu 3+ Characteristic peaks indicate Eu 3+ A self-reduction reaction occurs, producing Eu. 2+ .

[0066] from Figure 1 and Figure 2 As can be seen from the content, Example 1 has successfully prepared a biphase structure containing Eu. 2+ and Eu 3+ Heterojunction stress luminescent material, Ca3(PO4)2 / Ca5(PO4)3OH:Eu 2+ Eu3+ .

[0067] The heterojunction stress-luminescent material prepared in Comparative Example 1 was observed using a transmission electron microscope (TEM), and its TEM image is shown below. Figure 3 As shown. From Figure 3 It can be seen that the heterojunction stress luminescent material prepared in Comparative Example 1 has a distinct two-phase structure, and the two regions are directly connected by a clear interface without a transition layer or amorphous region, proving that the heterojunction material was successfully synthesized.

[0068] Performance testing

[0069] The heterojunction stress-luminescent materials prepared in Example 1 and Comparative Example 1, along with Ca3(PO4)2 and Ca5(PO4)3OH, were mixed with polydimethylsiloxane (PDMS) at a ratio of 1:1.2 and placed into a dumbbell-shaped mold with a depth of 1 mm. The mixtures were then dried in a 70°C oven for 1 hour. After demolding, the spectral intensity was obtained by stretching the film. Specifically, the heterojunction stress-luminescent material Ca3(PO4)2 / Ca5(PO4)3OH:Eu prepared in Example 1... 2+ Eu 3+ The spectral intensity comparison diagram of Ca3(PO4)2 and Ca5(PO4)3OH is shown in the figure below. Figure 4 As shown, from Figure 4 It can be seen that the Ca3(PO4)2 / Ca5(PO4)3OH:3.5%Eu prepared in Example 1 3+ Its stress luminescence intensity is about 2.3 times that of the Ca3(PO4)2 or Ca5(PO4)3OH heterojunction.

[0070] The comparison graph of the spectral intensity of the stress in the heterojunctions prepared in Example 1 and Comparative Example 1 is shown in the figure. Figure 5 As shown. From Figure 5 It can be seen that the heterojunction stress-luminescent material prepared in Example 1 emits light with a wavelength range covering the visible spectrum (400nm-700nm) after being excited by stress, and the intensity of mechanoluminescence is 10.7 times that of the heterojunction luminescent material in Example 1.

[0071] The stability of the heterojunction stress-luminescent material prepared in Example 1 was tested. The specific process included:

[0072] The heterojunction stress-luminescent material prepared in Example 1 was cut into 2 mm thick circular films. Then, a cylindrical iron block was excited by an electromagnetic gun to strike the circular films, causing stress-induced luminescence. After each excitation, the circular films were irradiated with a 365 nm light source for 5 minutes to charge them. This process was repeated until the circular films broke. The mechanoluminescence intensity of the circular films was recorded after each excitation. The results are as follows: Figure 6 As shown. From Figure 6It can be seen that the heterojunction stress luminescent material prepared by this invention does not show a significant decrease in mechanoluminescence intensity after 80 cycles, exhibiting excellent luminescence stability.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A heterojunction stress light emitting material, characterized by, Ca3(PO4)2 / Ca5(PO4)3OH:Eu 2+ , Eu 3+ ; Among them, Eu 2+ With Eu 3+ The molar ratio is 0.1-10:1; The preparation method of the heterojunction stress luminescent material comprises the following steps: S1, mixing CaCO3, NH4H2PO4 and Eu2O3, grinding and drying to obtain a mixture; S2, sintering the mixture under a mixed atmosphere to obtain the heterojunction stress luminescent material; The mass ratio of CaCO3, NH4H2PO4 and Eu2O3 in S1 is 0.9-1:0.6-0.7:0.001-0.015; The mixed atmosphere in S2 comprises nitrogen and hydrogen, and the volume ratio of nitrogen to hydrogen is 85-90:10-15; The sintering temperature in S2 is 1300-1400℃, and the sintering time is 0.5-5h.

2. The method of claim 1, wherein the method further comprises the step of: The preparation method of the heterojunction stress luminescent material comprises the following steps: ​ S1, mixing CaCO3, NH4H2PO4 and Eu2O3, grinding and drying to obtain a mixture; S2, sintering the mixture under a mixed atmosphere to obtain the heterojunction stress luminescent material; The mass ratio of CaCO3, NH4H2PO4 and Eu2O3 in S1 is 0.9-1:0.6-0.7:0.001-0.015; The mixed atmosphere in S2 comprises nitrogen and hydrogen, and the volume ratio of nitrogen to hydrogen is 85-90:10-15; The sintering temperature in S2 is 1300-1400℃, and the sintering time is 0.5-5h.

3. The method of claim 2, wherein the method further comprises the step of: The grinding time in S1 is 5-10min. ​ 4. The method of claim 2, wherein the method further comprises the step of: The drying temperature in S1 is 60-80℃, and the drying time is 10-20min. ​ 5. The heterojunction stress luminescent material of claim 1 is applied to a spectrum detector and an imaging sensor.

Images