Preparation method of perovskite single crystal wafer based on multi-junction epitaxial lift-off technology

Abstract

The invention provides a preparation method of a perovskite single crystal wafer based on a multi-junction epitaxial lift-off technology. The preparation method comprises the following steps: S1, providing a perovskite single crystal in a cubic crystal form as a mother substrate; s2, heteroepitaxial growth of a single crystal sacrificial layer is carried out on the mother substrate, in the heteroepitaxial growth process, a directional epitaxial end-capping reagent is used for adjusting the growth orientation of the single crystal sacrificial layer, the crystal phase of the single crystal sacrificial layer and the crystal phase of the mother substrate are kept consistent, and therefore the single crystal sacrificial layer with the planarized surface is formed; s3, heteroepitaxially growing a perovskite single crystal layer on the single crystal sacrificial layer with the planarized surface to form a multi-layer heterojunction structure; and S4, selectively dissolving the single crystal sacrificial layer by using the saturated precursor solution to realize stripping of the perovskite single crystal layer from the mother substrate, thereby obtaining the perovskite single crystal wafer. According to the preparation method provided by the invention, by introducing a crystal face orientation regulation and control and selective solvent stripping process, the size and yield bottlenecks of traditional mechanical stripping are broken through, the epitaxial orientation mismatch defect is eliminated, and large-scale production compatibility is realized.

Description

Technical Field

[0001] This invention relates to the field of semiconductor material manufacturing technology, and more specifically, to a method for preparing perovskite single-crystal wafers based on multi-junction epitaxial lift-off technology. Background Technology

[0002] Perovskite materials are valued for their excellent photoelectric properties (such as ultra-high light absorption coefficient > 10). 5 cm -1 Perovskite, with its wide tunable bandgap of 1.2-3.0 eV and single-crystal carrier diffusion length >100 μm, is considered a core material foundation for next-generation high-performance optoelectronic devices (solar cells, X-ray detectors, etc.) and integrated circuits. However, the development of perovskite single-crystal wafer devices has been slow due to the challenges in fabricating single-crystal wafers. Traditional mechanical exfoliation methods, commonly used in the semiconductor field, physically separate the epitaxial layer from the substrate, but this is complex and yields low results. Therefore, a simple and efficient epitaxial layer separation technology is urgently needed in the field of perovskite single-crystal material fabrication to promote the development of perovskite single-crystal wafer optoelectronic devices. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides a method for preparing perovskite single-crystal wafers based on multi-junction epitaxial exfoliation technology. By introducing crystal orientation control and selective solvent exfoliation processes, it breaks through the size and yield bottlenecks of traditional mechanical exfoliation, eliminates epitaxial orientation mismatch defects, and achieves compatibility for large-scale production.

[0004] The first aspect of this invention provides a method for preparing a perovskite single-crystal wafer based on multi-junction epitaxial exfoliation technology, comprising the following steps: S1. Provide a cubic perovskite single crystal as the mother substrate; S2. On the mother substrate, a single-crystal sacrificial layer is heteroepitaxially grown, wherein, during the heteroepitaxial growth process, an directional epitaxial end-capping agent is used to adjust the growth orientation of the single-crystal sacrificial layer so that the crystal phase of the single-crystal sacrificial layer is consistent with that of the mother substrate, thereby forming a single-crystal sacrificial layer with a planarized surface. S3. On the single-crystal sacrificial layer with a planarized surface, a perovskite single-crystal layer is heteroepitaxially grown to form a multilayer heterojunction structure. S4. The single-crystal sacrificial layer is selectively dissolved using a saturated precursor solution to peel the perovskite single-crystal layer from the mother substrate, thereby obtaining the perovskite single-crystal wafer.

[0005] In step S2, the directional epitaxial end-capping agent (such as cis-9-octadecylamine, OAm) regulates the growth orientation and surface morphology of the single-crystal sacrificial layer (such as MAPbI3) through molecular-level coordination interactions. The specific mechanism is as follows: During the growth of MAPbI3, the -NH2 groups of OAm interact with uncoordinated Pb groups on the crystal surface. 2+ Selective coordination of ions alters surface energy and the growth kinetics of each crystal plane. This coordination preferentially stabilizes... <100> The oriented crystal planes simultaneously suppress the growth of non-ideal orientations such as (211) and (330). Since the transformation of MAPbI3 from tetragonal to cubic crystal form involves the rotation or displacement of the Pb-I framework, the coordination of OAm adjusts the framework arrangement, causing the crystal to be reoriented to a more stable orientation. <100> Direction. To achieve a planarized surface, OAm promotes... <100> Uniform growth with a specific orientation reduces the formation of pyramid-shaped structures. <100> The consistent growth rate avoids the roughness caused by anisotropy. Simultaneously, OAM acts as a surfactant, coating the crystal surface and reducing the inhomogeneity of nucleation sites, guiding layered growth and ultimately forming a flat MAPbI3 layer. This flat surface provides an ideal substrate for the epitaxial growth of subsequent materials (such as MAPbBr3), ensuring seamless merging of single crystals. In other words, OAM achieves the transformation from a multi-oriented pyramid to a single flat surface through coordination-controlled crystal orientation and growth mode.

[0006] In one embodiment of the present invention, in step S1, the material of the cubic perovskite single crystal mother substrate is selected from at least one of the following materials: MAPbBr3, FAPbBr3, CsPbBr3, NaCl, KBr, NaBr, BaF2 and CaF2.

[0007] In one embodiment of the present invention, step S2 specifically includes the following steps: placing the mother substrate into a mixed solution of a precursor solution for growing a single crystal sacrificial layer and a directional epitaxial capping agent, heating it at 103°C for at least 5 minutes, and then removing it to obtain a mother substrate including a single crystal sacrificial layer with a planarized surface.

[0008] In one embodiment of the present invention, in step S2, the precursor solution used for growing the single-crystal sacrificial layer is FAPbI3 precursor solution, MAPbI3 precursor solution, or FA y MA 1-y Either the PbI3 precursor solution or the CsPbI3 precursor solution.

[0009] In one embodiment of the present invention, the directional epitaxial end-capping agent is any one of cis-9-octadecenylamine, 3-(decyldimethylamino)-propane-sulfonate inner salt, and hexadecyltrimethylammonium chloride.

[0010] In one embodiment of the present invention, step S3 specifically includes the following steps: immersing the mother substrate obtained in step S2, which includes a single crystal sacrificial layer with a planarized surface, into a saturated perovskite solution and soaking it at 50-150°C for at least 2 minutes to form a multilayer heterojunction structure.

[0011] In one embodiment of the present invention, in step S3, the solute in the perovskite solution is FAPbI. x Br 3-x FAPbBr3, MAPbI x Br 3-x MAPbBr3, FA y MA 1-y PbI x Br 3-x FA y MA 1-y PbBr3, CsPbI x Br 3-x At least one of CsPbBr3.

[0012] In one embodiment of the present invention, in step S4, the solvent in the saturated precursor solution is at least one of N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, γ-butyrolactone, and hydrobromic acid.

[0013] A second aspect of the present invention provides a perovskite single crystal wafer, which is prepared by the above-described preparation method.

[0014] Compared with the prior art, the embodiments of the present invention have the following beneficial effects: The method of the present invention has the following significant technical effects: 1. This invention provides a method for preparing perovskite single-crystal wafers based on multi-junction epitaxial lift-off technology. This method introduces a directional epitaxial capping agent to adjust the growth orientation of the sacrificial layer during heteroepitaxial growth of the single-crystal sacrificial layer, so that it is consistent with the crystal phase of the mother substrate, thereby effectively achieving planarization growth of the sacrificial layer.

[0015] 2. The present invention provides a method for preparing perovskite single crystal wafers based on multi-junction epitaxial lift-off technology. Through the synergistic effect of multi-junction epitaxial lift-off technology and crystal surface control, the efficient preparation of perovskite single crystal wafers of centimeters and above is successfully achieved, and the production cycle is shortened to 20 minutes, laying a technical foundation for the wafer-level mass production of perovskite optoelectronic devices.

[0016] 3. The present invention provides a method for preparing perovskite single crystal wafers based on multi-junction epitaxial exfoliation technology, which improves the quality of the wafers. The planarization growth of the sacrificial layer is achieved through directional epitaxial end-capping agent, avoiding lattice defects and surface roughness caused by epitaxial orientation mismatch in traditional methods. This improves the crystal quality of the subsequently grown perovskite single crystal layer, and the final perovskite single crystal wafer has higher purity and better optoelectronic properties.

[0017] 4. The method for preparing perovskite single-crystal wafers based on multi-junction epitaxial lift-off technology provided by this invention improves lift-off efficiency. The planarized sacrificial layer makes the subsequent solvent selective dissolution process more uniform and controllable, avoiding lift-off failure caused by uneven local dissolution, thereby significantly improving lift-off efficiency and wafer integrity. Traditional mechanical lift-off methods are prone to wafer damage, while the method of this invention can achieve non-destructive lift-off of perovskite single-crystal layers, greatly improving wafer yield.

[0018] 5. This invention provides a method for fabricating perovskite single-crystal wafers based on multi-junction epitaxial lift-off technology, achieving precise control over wafer dimensions. This invention can precisely control the thickness and size of the perovskite single-crystal layer by controlling parameters during the epitaxial growth process (such as growth temperature, growth rate, precursor concentration, etc.), thereby meeting the needs of different application fields. Directional epitaxy can control defects, resulting in better overall wafer uniformity and further improving the yield and lifespan of the final product.

[0019] 6. The method for preparing perovskite single crystal wafers based on multi-junction epitaxial peeling technology provided by this invention improves production efficiency and reduces production costs. The solvent dynamic equilibrium peeling process adopted in this invention has the advantages of simple operation and short cycle. Compared with the traditional mechanical peeling method, it greatly shortens the production cycle and reduces production costs, laying a technical foundation for the wafer-level mass production of perovskite optoelectronic devices. Attached Figure Description

[0020] Figure 1 The mechanism of multi-junction epitaxial lift-off technology is explained in detail for a series of optical images; among them, Figure 1 Figure a shows the cubic MAPbBr3 single crystal substrate obtained in the first step of Example 1; Figure 1 Figure b shows the pyramid-shaped epitaxial morphology of MAPbBr3 / MAPbI3 obtained in the second step of Example 1; Figure 1 Figure c shows the epitaxial morphology of MAPbBr3 / MAPbI3 with a planar configuration; Figure 1 Figure d shows the substrate morphology from step five; Figure 1 The middle figure shows the epitaxial morphology of MAPbBr3 during the gradual dissolution process. Figure 2To introduce OAm into the MAPbI3 precursor solution, optical images show that as the OAm addition amount increased from 0% to 10%, the epitaxial morphology of MAPbI3 gradually changed from a pyramidal structure to a planar configuration; among which, Figure 2 Figure a shows an optical image of the MAPbI3 epitaxial morphology when the OAm addition amount is 0%; where, Figure 2 Figure b shows an optical image of the MAPbI3 epitaxial morphology when the OAm addition amount is 3%; among them, Figure 2 Figure c shows an optical image of the MAPbI3 epitaxial morphology when the OAm addition amount is 6%; among them, Figure 2 Image d shows an optical image of the MAPbI3 epitaxial morphology when the OAm addition level is 9%; among them, Figure 2 The image in Figure e is an optical image of the epitaxial morphology of MAPbI3 when the amount of OAm added is 10%; Figure 3 The image shows a growth model and corresponding optical images of a planarized MAPbI3 single-crystal sacrificial layer and a further planarized epitaxial MAPbBr3 layer; among which, Figure 3 Figure a shows the growth model of a planarized MAPbI3 single-crystal sacrificial layer and a further planarized epitaxial MAPbBr3; where, Figure 3 Image b shows an optical image of the planarized epitaxial MAPbI3; in which, Figure 3 Image c shows an optical image of MAPbBr3 after further planarization epitaxy; Figure 4 A growth model for a single-crystal sacrificial layer of MAPbI3 with a pyramidal morphology and further epitaxial growth of MAPbBr3; Figure 5 Optical images of a pyramid-shaped MAPbI3 single-crystal sacrificial layer and a further epitaxial MAPbBr3 layer; in which Figure 5 Image a shows bright-field and dark-field optical images of a MAPbI3 single-crystal sacrificial layer with a pyramidal morphology. Figure 5 Image b shows bright-field and dark-field optical images of the further epitaxial MAPbBr3; Figure 6 The XRD patterns of each step in the preparation of the cubic MAPbBr3 single crystal substrate in Example 1 are shown, and the XRD patterns with and without OAM are compared. Detailed Implementation

[0021] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0022] The embodiments of the present invention will be described in detail below through specific examples.

[0023] Example 1 This embodiment provides a perovskite single crystal wafer, which is prepared by the following steps: The first step is to prepare a cubic MAPbBr3 single-crystal substrate, specifically including: 1) Dissolve 0.748 g of methylamine bromide (MABr) in 4 ml of anhydrous DMF in a 20 ml glass bottle to form a clear solution. Then, add 2.452 g of lead bromide (PbBr2) to the glass bottle and stir to obtain a nearly saturated clear MAPbBr3 solution. Subsequently, filter the mixed solution through a 0.22 μm PTFE filter to obtain the precursor solution, and then transfer the precursor solution to a clean 20 ml glass bottle.

[0024] 2) Place the glass vial on a hot plate at 25-35 °C and allow it to evaporate slowly without disturbance. After 24 hours, a bulk cubic MAPbBr3 single crystal substrate with a size in the centimeter range can be obtained. Figure 1 a) Figure 6 XRD patterns for each step in preparing cubic MAPbBr3 single crystal substrates.

[0025] The second step involves epitaxially growing a MAPbI3 single-crystal layer on MAPbBr3 as a sacrificial layer. A 1 cm... 2 The MAPbBr3 substrate was immersed in a 1.25 M MAPbI3 precursor solution (4 ml GBL), heated at 103°C for 5 minutes, and then removed. A black pyramidal morphology was observed on the surface after gently wiping with a lint-free paper. This indicates that the grown epitaxial MAPbI3 layer is not a planar structure. Figure 1 b、 Figure 2 a, Figure 4 , Figure 5 a).

[0026] The third step, to achieve orientation consistency among epitaxial layers in the multi-junction epitaxial stripping process, involves introducing OAM as a highly efficient end-capping agent into the MAPbI3 precursor solution. A MAPbBr3 / MAPbI3 substrate with a black pyramidal morphology is immersed in a 1.25M MAPbI3 precursor solution (4 ml GBL), heated at 130°C for 5 minutes, and then removed and gently wiped with lint-free paper. In this embodiment, the OAM addition amount is 3 wt%. As the OAM addition amount starts from 3 wt%, the MAPbI3 epitaxial morphology gradually changes from a pyramidal structure to a planar configuration. Figure 2 and Figure 3 ).

[0027] The fourth step is to place the substrate with a planar configuration from the previous step ( Figure 1 c) Immerse in a saturated MAPbBr3 / HBr solution and soak at 50°C for 2 minutes.

[0028] Step 5, place the substrate ( Figure 1 d) Rapidly transfer the saturated MAPbBr3 / HBr solution to another saturated MAPbBr3 / DMF solution and incubate at 80°C for 3 minutes. The thickness of the upper MAPbBr3 thin single crystal will continue to increase, while the middle MAPbI3 will gradually dissolve. Figure 1 e).

[0029] In the sixth step, the MAPbBr3 thin single crystal automatically detaches, the MAPbI3 in the middle completely dissolves, and the MAPbBr3 substrate at the bottom remains intact.

[0030] The preparation method provided in this embodiment achieves efficient separation of perovskite single crystal wafers by employing multi-junction epitaxial lift-off technology, crystal orientation control technology to achieve planar growth of the epitaxial layer, and solvent dynamic balance lift-off process.

[0031] Comparative Example The difference between this comparative example and Example 1 is that, when growing the sacrificial layer of single crystal 2 using heteroepitaxial growth, an efficient end-capping agent was not used to orient the growth orientation of the sacrificial layer of single crystal 2, and it is not consistent with the crystal phase of the substrate single crystal 1. Otherwise, it is the same as the example.

[0032] Because the growth orientation of the MAPbI3 sacrificial layer was not oriented using OAm, the subsequent epitaxial MAPbBr3 thin single crystals will continue to grow along the pyramid-shaped MAPbI3 sacrificial layer, exhibiting an uneven structure. Figure 4 and Figure 5 ), and it will be impossible to completely peel it off later.

[0033] Example 2 This embodiment provides a perovskite single crystal wafer. The preparation method of this perovskite single crystal wafer differs from that of Embodiment 1 only in that the amount of OAm added in the third step is 6wt%. The subsequent epitaxial MAPbBr3 thin single crystal will continue to grow along the MAPbI3 sacrificial layer with uneven morphology, exhibiting an uneven structure, which improves the surface flatness compared to Embodiment 1.

[0034] Example 3 This embodiment provides a perovskite single crystal wafer. The preparation method of this perovskite single crystal wafer differs from that of Embodiment 1 only in that the amount of OAm added in the third step is 9wt%. The subsequent epitaxial MAPbBr3 thin single crystal will continue to grow along the MAPbI3 sacrificial layer with uneven morphology, exhibiting an uneven structure, which improves the surface flatness compared to Embodiment 2.

[0035] Example 4 This embodiment provides a perovskite single crystal wafer. The preparation method of this perovskite single crystal wafer is different from that of Embodiment 1, except that the amount of OAm added in the third step is 10wt%.

[0036] Depend on Figure 2 It can be seen that as the amount of OAm added increases from 3wt% to 10wt%, the epitaxial morphology of MAPbI3 gradually changes from a pyramidal structure to a planar configuration. Figure 2 ).

[0037] Example 5 This embodiment provides a perovskite single-crystal wafer. The difference between the preparation of this perovskite single-crystal wafer and that of Embodiment 1 is that the single-crystal substrate in this embodiment is a cubic FAPbBr3 single-crystal substrate. This cubic FAPbBr3 is prepared by the following steps: N,N-dimethylformamide (DMF, 99.8%) and γ-butyrolactone (GBL, 99.9%) are uniformly mixed in an equal volume ratio, and the growth concentration is controlled at 1.4 mol / L. FABr and PbBr2 (98%) powders with a 1:1 molar ratio are dissolved in the mixed solution using a magnetic stirrer. Subsequently, the mixed solution is filtered through a 0.22 μm PTFE filter to obtain a precursor solution. The precursor solution is then placed in a beaker and placed on a hot stage, maintaining the nucleation temperature for approximately 7 h. During this process, a large number of small perovskite crystals of various shapes are generated at the bottom of the beaker. Regularly shaped small perovskite crystals are selected as seed crystals and then placed in 15 ml of a new precursor solution for individual growth. The main growth parameters are as follows: The heating rate is 3-5 °C / day at the increased temperature, and the temperature is maintained at a constant maximum temperature (55-60 °C) for 2-3 days. Finally, after a growth period of 7-10 days, large-sized and regularly shaped FAPbBr3 single-crystal substrates are obtained in the container.

[0038] Example 6 This embodiment provides a perovskite single-crystal wafer. The difference between the preparation of this perovskite single-crystal wafer and that of Example 1 is that the single-crystal substrate in this embodiment is cubic CsPbBr3. This cubic CsPbBr3 single-crystal substrate is prepared by the following steps: First, 1.0214 g CsBr (4.8 mmol), 3.5232 g PbBr2 (9.6 mmol), and 5.3 mL DMSO reagent are added sequentially to a 10 mL reagent bottle. Then, the reagent bottle is heated and stirred at 80°C. After 4-8 hours, the solution becomes clear. Subsequently, the solution is filtered using an organic filter with a 0.22 μm pore size. The filtered solution is collected in a 20 mL beaker to obtain a saturated CsPbBr3 precursor solution. Cover the mouth of the beaker with aluminum foil, leaving four small holes on the surface. Transfer the beaker to an 80 °C oven and set the heating rate to 1 °C / h until single crystals appear in the beaker. Continue growing at 85 °C. After one week, remove the single crystals.

[0039] The above embodiments are only used to further illustrate a process of efficient separation of perovskite single crystal wafers by using multi-junction epitaxial lift-off technology, crystal orientation control technology to achieve epitaxial layer planarization growth, and solvent dynamic balance lift-off process. However, the present invention is not limited to the embodiments. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

[0040] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for preparing a perovskite single crystal wafer based on a multi-junction epitaxial lift-off technology, characterized in that, The method comprises the following steps: S1, providing a cubic perovskite single crystal as a mother substrate; S2, hetero-epitaxially growing a single crystal sacrificial layer on the mother substrate, wherein, during the hetero-epitaxial growth, a directional epitaxy capping agent is used to adjust the growth orientation of the single crystal sacrificial layer, so that the single crystal sacrificial layer is consistent with the crystal phase of the mother substrate, thereby forming a single crystal sacrificial layer with a planarized surface; S3, hetero-epitaxially growing a perovskite single crystal layer on the single crystal sacrificial layer with a planarized surface, to form a multilayer heterojunction structure; S4, selectively dissolving the single crystal sacrificial layer by using a saturated precursor solution, to realize the peeling of the perovskite single crystal layer from the mother substrate, and to obtain a perovskite single crystal wafer.

2. The method of claim 1, wherein the method further comprises: In step S1, the material of the cubic perovskite single crystal mother substrate is selected from at least one of the following materials: MAPbBr3, FAPbBr3, CsPbBr3, NaCl, KBr, NaBr, BaF2 and CaF2.

3. The method of claim 1, wherein the method further comprises: Step S2 specifically comprises the following steps: placing the mother substrate into a mixed solution of a precursor solution for growing a single crystal sacrificial layer and a directional epitaxy capping agent, heating at 103℃ for at least 5 minutes, and then taking out, to obtain a mother substrate comprising a single crystal sacrificial layer with a planarized surface.

4. The method of claim 3, wherein the method further comprises: In step S2, the precursor solution for growing a single-crystal sacrificial layer is any one of a FAPbI3 precursor solution, a MAPbI3 precursor solution, a FA y MA 1-y PbI3 precursor solution, and a CsPbI3 precursor solution.

5. The method of claim 3, wherein the method further comprises: The directional epitaxy capping agent is any one of cis-9-octadecenylamine, 3- (decyldimethylamino) -propane-sulfonate inner salt and cetyltrimethylammonium chloride.

6. The method of claim 2, wherein the method further comprises: Step S3 specifically comprises the following steps: immersing the mother substrate comprising a single crystal sacrificial layer with a planarized surface obtained in step S2 into a saturated perovskite solution, and soaking at 50-150℃ for at least 2 minutes, to form a multilayer heterojunction structure.

7. The method of claim 2, wherein the method further comprises: In step S3, the solute in the perovskite solution is FAPbI x Br 3-x , FAPbBr3, MAPbI x Br 3-x , MAPbBr3, FAyMA 1-y PbI x Br 3-x , FA y MA 1-y PbBr3, CsPbI x Br 3-x , and CsPbBr3. 8.The perovskite single crystal wafer preparation method of claim 1, wherein, In step S4, the solvent in the saturated precursor solution is at least one of N, N-dimethylformamide, dimethyl sulfoxide, N-methyl pyrrolidone, γ-butyrolactone and hydrobromic acid.

9. A perovskite single crystal wafer, characterized by, Prepared by the method of any one of claims 1-8. Prepared by the method of any one of claims 1-8.

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