Cadmium-based perovskite material and preparation method thereof
By introducing Yb3+ doping with a radius similar to that of Cd2+ ions and an OA/OAm/TOPO triligand system into cadmium-based perovskite nanocrystals, the problems of oleylamine desorption at high temperatures and the difference in ionic radii of dopants were solved, achieving efficient nanocrystal synthesis and improved light conversion performance.
Patent Information
- Application Number
- CN202510759413.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-09
- Publication Date
- 2025-10-31
AI Technical Summary
Existing methods for synthesizing cadmium-based perovskite nanocrystals are difficult to apply to crystalline silicon solar cells, mainly due to the high energy requirements caused by the differences in the ionic radii of the dopant elements and the desorption problem of oleylamine at high temperatures, which affect the synthesis and performance of nanocrystals.
Yb3+, which has a similar ionic radius to Cd2+, was used as the dopant element. Combined with the high-temperature thermal injection method, the OA/OAm/TOPO triligand system was used to balance the coordination ability of Cd2+, stabilize the nanocrystalline surface, and avoid large particle agglomeration and defects.
Efficient doping of cadmium-based perovskite nanocrystals was achieved, breaking the forbidden transition, increasing the intensity of the PL emission peak, reducing surface defects of the nanocrystals, and improving the light conversion capability of the material.
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Figure CN120865899A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of perovskite material preparation technology, specifically to a cadmium-based perovskite material and its preparation method. Background Technology
[0002] Crystalline silicon solar cells, as a mature device type, have reached efficiency close to the Shockley-Queisser limit, making it difficult to improve device efficiency through process modifications. Considering the severe parasitic absorption of sunlight in the 300-400nm wavelength range by crystalline silicon solar cells, which significantly affects the short-circuit current, researchers have attempted to improve short-circuit current and thus device efficiency by depositing a light conversion layer on the surface of the crystalline silicon solar cell. This layer converts short-wavelength light into longer-wavelength light, which is more favorable for absorption by the absorption layer.
[0003] Currently used mainstream conversion materials (such as CdSe and CsPbCl3) all exhibit severe self-absorption, which significantly affects their light conversion capabilities. Therefore, researchers turned their attention to CsCdX3 (X = Cl, Br), a self-trapped exciton (STE) material with a large Stokes shift, broad emission peak, and low self-absorption. As an STE material, CsCdX3 exhibits parity-conserved forbidden transitions, preventing perovskites from producing intrinsic luminescence. Researchers then introduced other elements for doping to distort the lattice, breaking the forbidden transitions and achieving STE luminescence.
[0004] However, cadmium-based perovskite nanocrystals prepared by the hot-injection method, through Pb 2+ The emission peak produced after doping has a full width at half maximum (FWHM) of only about 50 nm, which is inconsistent with the broad emission peak produced by STE luminescence. Furthermore, combined with the absorption spectrum, it can be seen that CsCdBr3:Pb 2+ There is significant self-absorption, which is due to Pb 2+ The luminescence of doped CsCdBr3 is not STE luminescence, but rather the luminescence of CsPbBr3. Currently, the main doping element used in cadmium-based perovskites is Sb. 3+ Zr 4+ Plasma radius and Cd 2+ Ions with significantly different radii require high energy to incorporate, making thermal injection methods difficult to achieve. Hydrothermal methods have been attempted to incorporate these ions into perovskites, but this synthesis method cannot produce nanocrystals, hindering the application of cadmium-based perovskites synthesized using this method in crystalline silicon solar cells.
[0005] In order to achieve STE luminescence by breaking the forbidden transition while synthesizing nanocrystals, an attempt was made to combine it with Cd 2+ Yb with similar ionic radii 3+ To enhance PL emission, doping is performed using Yb. 3+ The doping of oleylamine (OAM) requires a relatively high temperature to achieve, while oleylamine (OAM) and Cd 2+ Insufficient coordination ability of Cd will lead to Cd exhibiting poor coordination during heating. 2+ Desorption from OAM affects the synthesis of perovskite nanocrystals. Summary of the Invention
[0006] This invention addresses the shortcomings of existing technologies by providing a cadmium-based perovskite material and its preparation method, employing a method similar to Cd... 2+ Yb with similar ionic radii 3+ Doping was performed, and to address the desorption problem of OAM at high temperatures, a dopant-like compound was introduced with Cd. 2+ TOPO, with its stronger coordination ability, balances Cd through the OA / OAm / TOPO triligand system. 2+ By combining coordination ability and nanocrystalline surface stability, cadmium-based perovskite nanocrystalline materials were obtained.
[0007] To address the aforementioned technical problems, the first aspect of this invention provides a method for preparing cadmium-based perovskite materials, comprising the following steps:
[0008] S1. Under vacuum, Cs2CO3, OA (oleic acid) and ODE (1-octadecene) are mixed to obtain a first mixture. After degassing and reacting to generate cesium oleate at a first temperature, a protective gas is introduced and heated to a second temperature until cesium carbonate is completely dissolved to obtain a cesium oleate precursor solution.
[0009] S2. Under vacuum, CdBr2, YbBr3, TOPO (tri-n-octylphosphine oxide), ODE, OAm (oleylamine), and OA are mixed to obtain a second mixture. After degassing at a third temperature, the mixture is heated to a fourth temperature, and the cesium oleate precursor solution is injected. After the reaction, the cadmium-based perovskite material CsCdBr3:Yb is obtained. 3+ .
[0010] This invention uses Cd 2+ Yb with similar ionic radii 3+ (99pm) was used as a dopant element, and high-temperature thermal injection was used to achieve efficient doping. The doping method is simple and effective. At the same time, in order to solve the desorption problem of OAM at high temperature, a dopant with Cd was introduced. 2+ According to the HSAB theory, TOPO with stronger coordination ability, Cd 2+It belongs to the category of soft acids, meaning it can interact to some extent with both soft and hard bases, but its interaction with soft bases is generally stronger. TOPO and oleylamine are also soft bases and can be used to react with Cd. 2+ Coordination, but TOPO avoids interaction with Cd at high temperatures. 2+ The mismatch between them is balanced by the OA / OAm / TOPO triligand system. 2 + Coordination ability and CsCdBr3:Yb 3+ The improved surface stability of nanocrystals effectively prevents the agglomeration of large particles during the nucleation stage, reducing surface defects and resulting in the cadmium-based perovskite nanocrystal material CsCdBr3:Yb. 3+ .
[0011] Furthermore, in S1, the volume ratio of OA to ODE is (1-2):(13-15), and the concentration of Cs2CO3 in the first mixture is 23-28 mg / mL.
[0012] Furthermore, in S1, the first temperature is 110-125℃, and the second temperature is 140-155℃.
[0013] Furthermore, in S2, the volume ratio of ODE, OAm, and OA is (9-11):(1-2):(1-2), the concentration of CdBr2 in the second mixture is 33-45 mg / mL, the concentration of YbBr3 in the second mixture is 8-11 mg / mL, and the concentration of TOPO in the second mixture is 0.26-0.36 g / mL.
[0014] Furthermore, in S2, the volume ratio of the second mixture to the cesium oleate precursor is (12-15):(1-2).
[0015] Furthermore, in S2, the third temperature is 110-125℃, and the fourth temperature is 255-265℃.
[0016] Furthermore, in S2, the reaction time is 5-10 seconds.
[0017] Furthermore, in S2, the reaction is followed by steps of cooling to room temperature in an ice bath, centrifugation, and extraction.
[0018] Furthermore, in S1, the protective gas is nitrogen.
[0019] The second aspect of the present invention provides a cadmium-based perovskite material prepared by the preparation method described in the first aspect.
[0020] The beneficial effects of this invention are:
[0021] This invention uses Cd2+ Yb with similar ionic radii 3+ As a dopant element, it can achieve efficient doping by combining high-temperature thermal injection method, which is simple and effective.
[0022] This invention introduces Cd 2+ TOPO, with its stronger coordination ability, balances Cd through the OA / OAm / TOPO triligand system. 2+ Coordination ability and CsCdBr3:Yb 3+ The nanocrystal surface stability effectively prevents the agglomeration of large particles during the reaction nucleation stage, reduces nanocrystal surface defects, and yields CsCdBr3:Yb 3+ Cadmium-based perovskite nanocrystal materials. Attached Figure Description
[0023] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0024] Figure 1 In the image, a and b are solution images of steps (2) and (3) in Comparative Example 1, respectively, and c and d are solution images of steps (2) and (3) in Example 1, respectively.
[0025] Figure 2 These are the absorption spectra of the materials obtained in Example 1 and Comparative Examples 1-2 of the present invention;
[0026] Figure 3 This is the XRD pattern of the material obtained in Example 1 of the present invention;
[0027] Figure 4 These are TEM images of the materials obtained in Example 1 of the present invention;
[0028] Figure 5 These are the PL spectra of the materials obtained in Example 1 and Comparative Example 2 of the present invention. Detailed Implementation
[0029] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0030] This embodiment provides a method for preparing cadmium-based perovskite materials, including the following steps:
[0031] S1. Under vacuum, Cs2CO3, OA and ODE are mixed to obtain a first mixture. After degassing and reacting to generate cesium oleate at a first temperature, a protective gas is introduced and heated to a second temperature until cesium carbonate is completely dissolved to obtain a cesium oleate precursor solution.
[0032] S2. Under vacuum, CdBr2, YbBr3, TOPO, ODE, OAm, and OA are mixed to obtain a second mixture. After degassing at a third temperature, the mixture is heated to a fourth temperature, and the cesium oleate precursor solution is injected. After the reaction, the cadmium-based perovskite material CsCdBr3:Yb is obtained. 3+ .
[0033] This embodiment uses Cd 2+ Yb with similar ionic radii 3+ (99pm) was used as a dopant element, and high-temperature thermal injection was used to achieve efficient doping. The doping method is simple and effective. At the same time, in order to solve the desorption problem of OAM at high temperature, a dopant with Cd was introduced. 2+ TOPO, with its stronger coordination ability, balances Cd through the OA / OAm / TOPO triligand system. 2+ Coordination ability and CsCdBr3:Yb 3+ The improved surface stability of nanocrystals effectively prevents the agglomeration of large particles during the nucleation stage, reducing surface defects and resulting in the cadmium-based perovskite nanocrystal material CsCdBr3:Yb. 3+ .
[0034] In a preferred embodiment, in S1, the volume ratio of OA to ODE is (1-2):(13-15), the concentration of Cs2CO3 in the first mixture is 23-28 mg / mL, the first temperature is 110-125℃, the second temperature is 140-155℃, and the protective gas is nitrogen.
[0035] In a preferred embodiment, in S2, the volume ratio of ODE, OAm, and OA is (9-11):(1-2):(1-2); the concentration of CdBr2 in the second mixture is 33-45 mg / mL; the concentration of YbBr3 in the second mixture is 8-11 mg / mL; and the concentration of TOPO in the second mixture is 0.26-0.36 g / mL. The volume ratio of the second mixture to the cesium oleate precursor solution is (12-15):(1-2). The third temperature is 110-125°C, and the fourth temperature is 255-265°C. The reaction time is 5-10 s. The reaction is followed by steps of cooling to room temperature in an ice bath, centrifugation, and extraction.
[0036] Another embodiment provides a cadmium-based perovskite material prepared by the preparation method described in the above embodiments.
[0037] Example 1
[0038] This embodiment relates to a method for preparing a cadmium-based perovskite material, including the following steps:
[0039] (1) Under vacuum, 0.4 g Cs2CO3, 1.25 mL OA and 15 mL ODE were mixed and stirred continuously at 120 °C until bubbling stopped. Nitrogen gas was introduced and the mixture was heated to 150 °C and stirred until all Cs2CO3 dissolved to obtain a clear cesium oleate precursor solution, wherein the concentration of CsOA was about 0.16 M.
[0040] (2) Place 0.5g CdBr2, 0.123g YbBr3, 4g TOPO, 10mL ODE, 1mL OAm and 1mL OA in a three-necked flask and degas at 120℃ for 1h under vacuum;
[0041] (3) The temperature was then raised to 260℃, followed by the injection of 2 mL of cesium oleate precursor solution. After reacting for 5 seconds, the mixture was cooled to room temperature on an ice bath and centrifuged at 12000 r / min for 6 min. After centrifugation, the precipitate at the bottom was collected, cyclohexane was added, and the mixture was shaken. After centrifugation again at 8000 r / min for 5 min, the supernatant was collected to obtain the cadmium-based perovskite nanocrystalline material CsCdBr3:Yb. 3+ .
[0042] Comparative Example 1
[0043] The difference between this comparative example and Example 1 is that TOPO is not added in step (2), while other steps and parameters remain unchanged, specifically:
[0044] (1) Under vacuum, 0.4 g Cs2CO3, 1.25 mL OA and 15 mL ODE were mixed and stirred continuously at 120 °C until bubbling stopped. Nitrogen gas was introduced and the mixture was heated to 150 °C and stirred until all Cs2CO3 dissolved to obtain a clear cesium oleate precursor solution, wherein the concentration of CsOA was about 0.16 M.
[0045] (2) Place 0.5g CdBr2, 0.123g YbBr3, 10mL ODE, 1mL OAm and 1mL OA in a three-necked flask and degas at 120℃ for 1h under vacuum;
[0046] (3) The temperature was then raised to 260°C, and 2 mL of cesium oleate precursor solution was injected. After reacting for 5 seconds, the mixture was cooled to room temperature in an ice bath and centrifuged at 12000 r / min for 6 min. After centrifugation, the precipitate at the bottom was collected, cyclohexane was added and shaken, and the mixture was centrifuged again at 8000 r / min for 5 min. Finally, the supernatant was collected to obtain the cadmium-based perovskite material.
[0047] Comparative Example 2
[0048] The comparative example is cadmium-based perovskite material CsCdBr3.
[0049] Test case
[0050] Figure 1 Images a and b in Comparative Example 1 show the solutions from steps (2) and (3), respectively. Figure 1 Images c and d in Example 1 show the solutions from steps (2) and (3), respectively. It can be seen that in Comparative Example 1, when using the OA / OAm dual-ligand, the solution appears transparent yellow at 120°C. This is due to the presence of Cd. 2+ Insufficient coordination ability with OAm results in a large amount of free Cd in the solution. 2+ Subsequently, during the heating process, it was clearly observed that when the temperature rose to 260℃, the solution changed from clear to turbid, further confirming the presence of Cd. 2+ The coordination ability with OAm is insufficient. In Example 1, using the OA / OAm / TOPO triligand system, the solution was colorless and transparent at 120°C, and remained stable even when heated to 260°C. This indicates that TOPO has insufficient coordination with Cd. 2+ With enhanced coordination ability and the ability to maintain stability even at high temperatures, it is evident that the introduction of the three-ligand strategy can effectively stabilize CsCdBr3:Yb. 3+ The nanocrystalline surface effectively avoids the formation of large particles in the three-necked flask during the nucleation stage of the reaction.
[0051] Figure 2 The absorption spectra of the materials obtained in Example 1 and Comparative Examples 1-2 show that the three-ligand strategy in Example 1 reduces the tailing of the absorption spectrum, indicating a reduction in surface defects of the nanocrystals. This further confirms the effectiveness of the three-ligand system in stabilizing CsCdBr3:Yb. 3+ Nanocrystalline surface.
[0052] Figure 3 The image shows the XRD pattern of the material obtained in Example 1, indicating that CsCdBr3:Yb was successfully synthesized. 3+ Nanocrystals, through Figure 4 The TEM image shows that the nanocrystal surface structure is stable and almost defect-free.
[0053] Figure 5 The PL spectra of the materials in Example 1 and Comparative Example 2 show that the materials used in Example 1 are similar to those of Cd. 2+ Yb with closer ionic radii 3+ After ion doping, the forbidden transition of CsCdBr3 is broken, and the intensity of the PL emission peak is significantly improved.
[0054] In summary, this invention utilizes Cd 2+ Yb with similar ionic radii3+ As a doping element, high-efficiency doping is achieved by combining high-temperature thermal injection, a simple and effective doping method; introducing elements similar to Cd... 2+ TOPO, with its stronger coordination ability, balances Cd through the OA / OAm / TOPO triligand system. 2+ Coordination ability and CsCdBr3:Yb 3+ The nanocrystal surface stability effectively prevents the agglomeration of large particles during the reaction nucleation stage, reduces nanocrystal surface defects, and yields CsCdBr3:Yb 3+ Cadmium-based perovskite nanocrystal materials.
[0055] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.
Claims
1. A method for preparing a cadmium-based perovskite material, characterized in that, Includes the following steps: S1. Under vacuum, Cs2CO3, OA and ODE are mixed to obtain a first mixture. After degassing and reacting to generate cesium oleate at a first temperature, a protective gas is introduced and heated to a second temperature until cesium carbonate is completely dissolved to obtain a cesium oleate precursor solution. S2. Under vacuum, CdBr2, YbBr3, TOPO, ODE, OAm, and OA are mixed to obtain a second mixture. After degassing at a third temperature, the mixture is heated to a fourth temperature and the cesium oleate precursor solution is injected. After the reaction, the cadmium-based perovskite material is obtained.
2. The method for preparing cadmium-based perovskite material as described in claim 1, characterized in that, In S1, the volume ratio of OA to ODE is (1-2):(13-15), and the concentration of Cs2CO3 in the first mixture is 23-28 mg / mL.
3. The method for preparing cadmium-based perovskite material as described in claim 1, characterized in that, In S1, the first temperature is 110-125℃, and the second temperature is 140-155℃.
4. The method for preparing cadmium-based perovskite material as described in claim 1, characterized in that, In S2, the volume ratio of ODE, OAm, and OA is (9-11):(1-2):(1-2), the concentration of CdBr2 in the second mixture is 33-45 mg / mL, the concentration of YbBr3 in the second mixture is 8-11 mg / mL, and the concentration of TOPO in the second mixture is 0.26-0.36 g / mL.
5. The method for preparing cadmium-based perovskite material as described in claim 1, characterized in that, In S2, the volume ratio of the second mixture to the cesium oleate precursor is (12-15):(1-2).
6. The method for preparing cadmium-based perovskite material as described in claim 1, characterized in that, In S2, the third temperature is 110-125℃, and the fourth temperature is 255-265℃.
7. The method for preparing cadmium-based perovskite material as described in claim 1, characterized in that, In S2, the reaction time is 5-10 seconds.
8. The method for preparing cadmium-based perovskite material as described in claim 1, characterized in that, In S2, the reaction is followed by steps of cooling to room temperature in an ice bath, centrifugation, and extraction.
9. The method for preparing cadmium-based perovskite material as described in claim 1, characterized in that, In S1, the protective gas is nitrogen.
10. A cadmium-based perovskite material prepared by the preparation method according to any one of claims 1-9.