CN111139072A - Perovskite material modified by non-protonized ligand - Google Patents
Perovskite material modified by non-protonized ligand Download PDFInfo
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Abstract
The invention relates to a perovskite material modified by non-protonation ligands, which is prepared by the reaction of organic divalent metal carboxylate and organic phosphide at high temperature, wherein carboxylate ligands are provided after the reaction of the organic divalent metal carboxylate to be combined on the surface of the perovskite, the organic phosphide is converted into organic phosphide to be adsorbed on the surface after the reaction, and divalent metals are enriched on the surface of the perovskite. Amine and acid precursors in the traditional method are avoided in the preparation process, an amine-free and acid-free reaction environment is constructed, and the surface of the perovskite material which is rich in divalent cations and is modified by acid radical ligands is finally formed. The obtained surface modification structure can obviously improve the light, heat and water-oxygen stability of the perovskite material and effectively slow down the degradation of the perovskite material under the water vapor condition.
Description
Technical Field
The invention relates to a stable perovskite material modified by non-protonized ligand on a metal-rich surface.
Background
In recent years, semiconductor nano-fluorescent materials have been increasingly applied to the field of practical display illumination because of their excellent light emitting characteristics. As a novel fluorescent material, the all-inorganic halide perovskite material has high luminous efficiency, narrow emission line width, continuously tunable light emission spectrum and other advantages, so that the all-inorganic halide perovskite material has great application potential in the fields of light emitting diodes, solar cells, photoelectric detectors and the like. The current methods for preparing all-inorganic halide perovskite materials mainly comprise a ligand-assisted reprecipitation method and a high-temperature thermal injection method. The two methods can realize continuous adjustment of the luminescence spectrum by regulating the concentration of the ligand in the solution and the components of the halogen element in the precursor, wherein the high-temperature heat injection method can also regulate and control the emission wavelength of the material by the injected temperature.
Although all-inorganic perovskite materials have many advantages, the materials are ionic crystals and are more sensitive to external environments such as humidity, illumination and the like compared with traditional covalent semiconductor nanomaterials such as II-VI group nanomaterials. More importantly, the surface of the perovskite material is generally rich in halogen and univalent cations such as IA group element Cs and the like, and is modified by amine and acid ligand together. Proton transmission easily occurs between the ligands, so that the dynamic property of the combination of the ligands and the surface of the material is enhanced, and proton exchange and desorption easily occur when a polar solvent is encountered to cause the degradation of the material. In addition, the bonding force between the amine ligand and the surface halogen element is not strong, and the surface IA element is easy to hydrate and decompose. Unstable surface modification causes poor stability and reduced luminous efficiency of the perovskite material, so that the surface ligand modification of the perovskite material needs to be optimized to improve the dispersibility, stability and luminous efficiency of the perovskite material.
The current studies on the stability of perovskite materials are mainly focused on surface ligand modification, polymer protection and heterostructure.
Organic amine and organic acid are generally used as ligands in the method for preparing the perovskite material, particularly the organic amine is used, although the dissolution of the precursor metal halide can be improved, the proton exchange process can occur between the amine and the acid. The existence of the process can lead to the weakening of bonding between the ligand and surface ions, the ligand is easy to desorb from the surface of the nanocrystalline, and the perovskite material has strong sensitivity to light, air and polar solvents such as water, ethanol and the like, so the material is easy to degrade in air with high humidity or under continuous irradiation of exciting light, and the stability of the material is poor and the fluorescence is attenuated. The solution to the problem of stability of materials in light, heat and polar solvents is a crucial issue if practical applications of perovskite materials are to be realized. The stability of the material is improved by surface ligand modification, and the problems of protonation of the ligand and weak binding capacity of the ligand and the perovskite surface are mainly solved.
Disclosure of Invention
Aiming at the problems that the perovskite material is sensitive to illumination and polar solvents and the material is easy to degrade, the invention aims to construct an amine-free and acid-free reaction environment by avoiding amine and acid precursors in the traditional method in the preparation process, and finally form the perovskite material surface which is rich in divalent cations and is modified by acid radical ligands. The obtained surface modification structure can obviously improve the light, heat and water-oxygen stability of the perovskite material and effectively slow down the degradation of the perovskite material under the water vapor condition. Wherein organic phosphorus is used for replacing organic amine and organic acid to promote the dissolution of metal halide in the reaction process, and the reaction is assisted. The carboxylate coordinated on the surface of the perovskite is derived from metal saturated or unsaturated fatty salt. In addition, the reaction of the organic phosphorus with the carboxylate to convert it to an organic phosphorus oxide may also result in a small amount of adsorption on the perovskite surface. In the traditional method, proton transport is easily caused in the reaction due to the existence of amine and acid, decomposition of perovskite is induced, and hydrolysis is also induced due to the surface enrichment of IA group elements, so that the stability is poor. The preparation method effectively avoids the use of protonated ligand and the existence of surface univalent cation. The carboxylate has strong coordination with positive divalent cations enriched on the surface of the perovskite material, and is not easy to desorb from the surface of the perovskite.
The technical scheme provided by the invention is that,
the perovskite material modified by the non-protonized ligand is characterized by being prepared by the reaction of organic divalent metal carboxylate and organic phosphide at high temperature, wherein carboxylate ligands are provided after the reaction of the organic divalent metal carboxylate to be combined on the surface of the perovskite, the organic phosphide is converted into organic phosphorus oxide to be adsorbed on the surface after the reaction of the organic divalent metal carboxylate, and divalent metal is enriched on the surface of the perovskite.
The molar ratio of carboxylate radical to organic phosphide in the organic divalent metal carboxylate is as follows: the ratio of organophosphate (organophosphate is based on the total moles of the substance, and one divalent organic metal carboxylate contains 2 carboxylates, so the amount of carboxylate should be twice the moles of divalent organic metal carboxylate) is 5: 1-1: 3, preferably 1: 2.5.
The particle size of a single fluorescent nanocrystal of the perovskite material is 3-50 nm.
The preparation method of the perovskite material comprises the following steps:
preparing a cation precursor solution of the metal Cs and an organic divalent metal carboxylate precursor;
mixing metal halide with a nonpolar organic solution and an organic phosphorus solution at room temperature, putting the mixture into a three-neck flask, heating the mixture to a temperature below the boiling point of the nonpolar organic solution and higher than 100 ℃, and continuously heating the mixture until the metal halide is completely dissolved to obtain a mixed solution; then quickly injecting a cation precursor solution of metal Cs and an organic divalent metal carboxylate precursor into the mixed solution, reacting for 30 seconds to 5 minutes, removing the heating device, and quickly cooling the reaction solution to room temperature in an ice bath to obtain a stable perovskite solution modified by the non-protonized ligand; and finally, centrifugally cleaning the solution by ethyl acetate to obtain the perovskite nano-crystal with the divalent metal-rich surface, wherein the carboxylate is coordinated with the metal ions on the surface of the perovskite.
The application provides another perovskite material preparation method, which comprises the following steps:
preparing a cation precursor solution of the metal Cs and an organic divalent metal carboxylate precursor;
mixing metal halide with a nonpolar organic solution, an organic phosphorus solution and an organic divalent metal carboxylate precursor at room temperature, putting the mixture into a three-neck flask, heating the mixture to a temperature below the boiling point of the nonpolar organic solution and higher than 100 ℃, and continuously heating the mixture until the metal halide is completely dissolved to obtain a mixed solution; then quickly injecting a cation precursor solution of metal Cs into the mixed solution, after the reaction is kept for 30 seconds to 5 minutes, removing the heating device, and quickly cooling the reaction solution to room temperature in an ice bath to obtain a stable perovskite solution modified by the non-protonized ligand; and finally, centrifugally cleaning the solution by ethyl acetate to obtain the perovskite nano-crystal with the divalent metal-rich surface, wherein the carboxylate is coordinated with the metal ions on the surface of the perovskite.
The non-polar organic solution is Octadecene (ODE), octadecane, tetradecane, paraffin oil or xylene.
The metal halide being PbCl2、PbBr2、PbI2、SnCl2、SnBr2、SnI2And the like.
The organic divalent metal carboxylate contains dicarboxylic acid radicals, the length of a carbon chain is 4-20, and the organic divalent metal carboxylate specifically comprises one or more of stearate, oleate, laurate and myristate; the divalent metal salt is one or more of lead, zinc, tin, manganese and cadmium; the organic phosphide is tri-n-octyl phosphine or tributyl phosphine.
The high temperature reaction temperature of the organic divalent metal carboxylate and the organic phosphide is 120-220 ℃.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, the organic phosphide and the organic carboxylate are introduced into the preparation method of the perovskite material to replace aliphatic amine or organic acid which is required to be used in the traditional preparation method, so that the surface of the prepared perovskite nanocrystal can be modified with a layer of non-protonized ligand without containing amino groups, and the perovskite nanocrystal with the non-protonized modified surface is realized; on the other hand, because the metal ions in the metal carboxylate are already in a pre-combined state with the carboxylate, the metal ions with the carboxylate can be directly bonded with the halogen to form the carboxylate modified perovskite in the reaction without going through the process of reacting the carboxylic acid with the metal ions used in the conventional method. Transmission electron microscope observation shows that the perovskite material modified by the surface non-protonized ligand has better size distribution and presents a cubic structure. Because the fluorescence intensity of the material is attenuated with time under the influence of factors such as light, water and the like,the invention can effectively slow down the attenuation of the material under continuous excitation, namely, the stability of the material can be effectively improved. Exciting light 10w/cm at air temperature of 25 deg.C, relative humidity of 32-38% and 440nm2Under the continuous excitation of (1), the all-inorganic perovskite material prepared by using the traditional aliphatic amine decays by 80% of the strength after photoactivation in about 29 hours, while the perovskite material prepared by using the method disclosed by the invention only decays by 5.8% after 140 hours of test under the same test conditions; excitation light of 440nm in water at 25 deg.C and 10w/cm2Under the continuous excitation of (1), the perovskite material prepared by using the traditional aliphatic amine decays by 80% after 10 hours, while the perovskite material prepared by using the method decays by 25% after 40 hours of test under the same test conditions; the perovskite and the polymethyl methacrylate are mixed and then packaged into a blue LED for lighting test, and the stability is basically not attenuated after 75 hours of test, so that the stability is effectively improved compared with the perovskite modified by the aliphatic amine ligand.
The invention mainly aims to improve the stability of the perovskite material, and the luminous intensity of the material can be gradually attenuated because the material can be gradually decomposed by factors such as light or water oxygen, so that the comparison of the attenuation speed of the luminous intensity of the material in the published preparation method and the attenuation speed of the luminous intensity of the perovskite material can most directly show the advantages.
The perovskite is directly synthesized by using the material in the application to improve the characteristics of the material, the indissolvable metal halide is used, and meanwhile, the organic divalent metal carboxylate belongs to the organic salt, so that the formation of the perovskite surface modification ligand is facilitated, and the stability of the perovskite material is facilitated. And the perovskite surface in this application does not have a pore-like structure. The ligand initially put into the perovskite material contains organic phosphorus, but organic phosphorus oxide is finally generated in the reaction process and is actually combined with the surface of the perovskite, and the organic phosphorus oxide is not actually combined with atoms on the surface of the perovskite and only has a weak interaction with the surface, so that the perovskite material modified by the carboxylic acid ligand is finally and actually obtained in the perovskite material, and the stability of the perovskite material under the conditions of water, oxygen and heat is improved.
Drawings
FIG. 1: the overall structure schematic diagram of the surface-modified perovskite material prepared in example 1;
FIG. 2 is a transmission electron micrograph and an X-ray diffraction pattern of the perovskite material prepared in example 1; wherein a is a Transmission Electron Microscope (TEM) image of the perovskite material prepared in example 1, and b is an X-ray diffraction pattern (XRD) of the perovskite material prepared in example 1 and a perovskite material prepared by a conventional amine group;
FIG. 3: the perovskite material prepared in the example 1 and the perovskite material modified by the traditional amine-based ligand have the relative humidity of 38 percent and 10w/cm at the temperature of 25 DEG C2The stability curve in air under the excitation of 440nm exciting light;
FIG. 4: the perovskite material prepared in the example 1 and the perovskite material modified by the traditional amine-based ligand are 10w/cm at the temperature of 25 DEG C2The 440nm exciting light of (1) is used for exciting a stability curve in water;
FIG. 5: the perovskite material prepared in example 1 was at 10w/cm2The thermal stability curve under the excitation of 440nm exciting light;
FIG. 6 is an EDS energy spectrum test comparison of the element types and contents of the perovskite material of the invention and the conventional aliphatic amine modified perovskite material prepared in example 1; wherein a is the EDS energy spectrum of the material of the invention, and b is the energy spectrum of the traditional fatty amine modified perovskite material.
FIG. 7: of the perovskite Material and reactive precursor of the invention prepared in example 131P liquid nmr spectrum.
FIG. 8: x-ray photoelectron spectroscopy (XPS) of the perovskite material of the present invention prepared in example 1.
FIG. 9: infrared spectra of the reaction precursors tri-n-octylphosphine, lead stearate, commercially available tri-n-octylphosphine oxide, octadecene and cleaned perovskite material of the present invention used in example 1.
FIG. 10 is a graph of the stability of the perovskite material prepared in example 1 after mixing with polymethyl methacrylate to form a thin film, after excitation by a blue LED.
Detailed Description
The invention is further described with reference to the following figures and detailed description. The specific examples are only for illustrating the present invention in further detail and do not limit the scope of protection of the present application.
The perovskite material involved in the invention may be ternary and multicomponent halogenated perovskite compounds of the basic formula MNX3Wherein M is Cs, N is one or a plurality of Pb and Sn, and X is one or a plurality of Cl, Br, I and the like. The perovskite material comprises the following compounds:
CsPbX3compounds, in particular CsPbCl3、CsPbBr3、CsPbI3、CsPbBrxCl3-x、CsPbBrxI3-x；
CsSnX3Compounds, in particular CsSnCl3、CsSnBr3、CsSnI3、CsSnBrxCl3-x、CsSnBrxI3-x；
Other CsNX3Compound, in particular CsPbxSn1-xCl3、CsPbxSn1-xBr3、CsPbxSn1-xI3. Wherein the method described in the present application is applied to CsPbBr3The perovskite effect is optimal.
The modified ligand involved in the invention contains organic carboxylate and adsorbs organic phosphorus oxide on the surface. The perovskite material is formed by crystallization of a divalent organic metal carboxylate through rapid injection into a metal halide solution containing an organophosphorus ligand at high temperature. Wherein organic phosphorus in the ligand reacts with part of carboxylate radicals to generate organic phosphorus oxide, part of carboxylate radicals are coordinated with divalent metal ions on the surface of the perovskite, and the organic phosphorus oxide is adsorbed on the surface to form a stable all-inorganic perovskite material with a metal-rich surface. In the preparation process, the organic phosphorus can provide a weak coordination environment to promote the dissolution of a reaction precursor, and the organic carboxylate radicals have strong coordination with metal cations in the perovskite, so that the organic phosphate radicals are not easy to desorb in the purification process, and the stability of the perovskite material can be enhanced. Wherein the molar ratio of the carboxylate to the organic phosphide is as follows: organic phosphates are 5:1 to 1:3, preferably 1: 2.5.
Wherein the carboxylic acid ligand comprises oleate, stearate, laurate, tetradecanoate and the like;
wherein the organophosphorus oxide is obtained by converting organophosphorus compound, and comprises tri-n-octyl phosphine, tributylphosphine and the like.
The fluorescent perovskite nano material provided by the invention has a fluorescent nano material crystal with the particle size of 10-50nm and a surface ligand thereof.
The surface ligand of the perovskite material can be prepared by reacting organic divalent metal carboxylate and organic phosphorus, wherein the organic divalent metal carboxylate is provided with organic carboxylate ligands after reaction and is combined on the perovskite surface, and the organic phosphorus precursor is converted into organic phosphorus oxide after reaction and is adsorbed on the surface. The organic metal carboxylate contains dicarboxylic acid radicals, wherein the metal ions can be divalent metal ions in perovskite and other divalent metal ions, the length of the carbon chain is 4-20, and the organic metal carboxylate specifically comprises stearate, oleate, laurate, myristate and the like, such as lead stearate, lead oleate (the longer the carbon chain is, the better the light stability is, the more stable the light stability is), lead laurate, lead myristate, zinc stearate, zinc oleate, zinc laurate, tin stearate, tin oleate, tin laurate, manganese stearate and manganese oleate (divalent metal salts); the organophosphorus precursor can be tri-n-octylphosphine, tributylphosphine.
The metal halide being PbCl2、PbBr2、PbI2、SnCl2、SnBr2、SnI2One or more of (a).
The preparation method of the perovskite material comprises the following steps:
preparing a cation precursor solution of the metal Cs and an organic divalent metal carboxylate precursor;
and mixing the metal halide precursor, a nonpolar organic solvent with a high boiling point and an organic phosphorus solution at room temperature, putting the mixture into a three-neck flask, dissolving the metal halide, heating to 120-220 ℃, continuously heating for 10-30 minutes until the metal halide precursor is dissolved, quickly injecting the mixed solution of M cations and the organic divalent metal carboxylate precursor into the mixed solution, reacting for 30 seconds-5 minutes, removing the heating device, and quickly cooling the reaction solution to room temperature in an ice bath to obtain the non-protonized ligand modified divalent metal-rich stable perovskite solution. And finally, centrifugally cleaning the perovskite solution by using ethyl acetate to obtain the solid perovskite material.
Wherein the nonpolar organic solvent is carrier solvent for reaction, and can be Octadecene (ODE), octadecane, tetradecane, paraffin oil, xylene, etc.
The core innovation point of the invention is mainly that organic carboxylate is used as a ligand coordinated on the surface of the perovskite nanocrystal and a perovskite material rich in cations (the cations are metal ions introduced by organic divalent metal carboxylate) surface is formed, and PbBr is added in the preparation process of the perovskite material in the prior art2The perovskite nano-crystal is prepared by using fatty amine such as oleylamine and the like as a ligand, the fatty amine is easy to have the phenomenon of proton transmission, namely the perovskite is decomposed, and the stability of the material is poor.
The initial ligand material of the present invention is, for example, a phosphide such as tri-n-octylphosphine and a carboxylate such as lead stearate, the presence of which during the heating reaction causes the phosphide to be oxidized to form trioctylphosphine oxide, with the final carboxylate as a ligand bound to divalent cations (e.g., Pb) on the surface of the perovskite nanocrystal2+) While the weak interaction of trioctylphosphine oxide with the surface is believed to be adsorption on the surface. The preparation method does not use oleylamine which influences the stability of the perovskite, and uses lead stearate and other organic substancesThe metal carboxylate, rather than the organic acid, contributes to the enhanced stability of the perovskite.
The key point in the preparation is that the initially input materials are organic phosphide and metal carboxylate, and after reaction, the organic phosphide is converted into organic phosphine oxide, and finally, perovskite rich in metal cations is formed. And meanwhile, two types of ligands, namely organic phosphide and carboxylate, are used, and the obtained metal-rich surface is an important factor for better stability of the perovskite material.
Example 1: high-stability all-inorganic CsPbBr prepared from lead oleate precursor3Perovskite materials
First, a cesium oleate precursor solution is prepared
At room temperature, 0.814g of Cs2CO3Mixing with 2.5ml oleic acid and 40ml Octadecylene (ODE) solution, adding into 100ml three-neck flask, stirring at 500 rpm under magnetic stirring, vacuumizing for 15 min until no bubbles are generated in the mixed solution, introducing nitrogen, maintaining stirring and nitrogen atmosphere, heating to 120 deg.C within 5 min, heating to 120 deg.C, vacuumizing for 30 min to remove water vapor until no bubbles are generated in the mixed solution, introducing nitrogen, maintaining stirring and nitrogen atmosphere, heating to 150 deg.C within 5 min, and continuously heating at 150 deg.C for 120 min until Cs is generated2CO3Reacting with oleic acid to form clear solution, cooling to room temperature to obtain cesium oleate, centrifugally cleaning at 6000 rpm for 10 minutes to remove excessive acid in the solution, and re-dispersing the obtained precipitate into ODE for later use.
Second, preparation of lead stearate precursor
The lead stearate used in the second step was commercially available lead stearate powder.
Thirdly, preparing the stearate modified CsPbBr3Perovskite nanocrystals.
Mixing 0.188mmol of lead bromide, 5mL of ODE solution and 0.3mL of tri-n-octylphosphine solution at room temperature, adding the mixture into a 25 mL three-neck flask, vacuumizing for 15 minutes under the stirring of magnetons at the rotation speed of 500 revolutions per minute until no bubbles are generated in the mixed solution, introducing nitrogen, heating to 120 ℃ within 5 minutes, maintaining the temperature of 120 ℃ for vacuumizing for 30 minutes until no bubbles are generated in the mixed solution, introducing nitrogen, heating to 160 ℃ within 5 minutes, and continuously heating for 15-30 minutes while maintaining the temperature of 160 ℃. Heating cesium oleate at room temperature to a clear solution at 100 ℃, mixing 0.4mL of cesium oleate with 0.1mmol of lead stearate, quickly injecting the mixture into a three-neck flask, removing a heating device after reacting for 30 seconds, and quickly cooling the reaction solution to room temperature in an ice bath to obtain the perovskite nanocrystal with rich metal (metal introduced by organic carboxylate) surface, wherein the metal ions on the surface of the perovskite are coordinated by organic carboxylate.
Fourthly, purifying the perovskite nanocrystal
Mixing the perovskite nano-crystal prepared in the third step with ethyl acetate in a volume ratio of 1:3, adding the mixture into a centrifugal tube, centrifugally cleaning the mixture for 5 minutes at the rotating speed of 6000 rpm, removing the upper-layer impurity solution after the perovskite nano-crystals are completely precipitated, and re-dispersing the perovskite nano-crystals into the toluene solution.
The reaction process of the ligand-coordinated perovskite material of the invention obtained in example 1 is shown in fig. 1, tri-n-octylphosphine is dissolved by coordination with lead bromide, and crystallized into CsPbBr after cesium oleate and lead stearate are added3In the perovskite nanocrystalline, a divalent metal ion with organic carboxylate radical in lead stearate is bonded with bromide ion in perovskite to form lead-rich surface carboxylate radical modified perovskite nanocrystalline, and the residual stearate radical and tri-n-octylphosphine react to generate tri-n-octylphosphine oxide to be adsorbed on the surface of the nanocrystalline.
In fig. 2, a and b are a morphology of the nanocrystal obtained by a transmission electron microscope of the material obtained in example 1 and an X-ray diffraction spectrum of the material obtained in example 1 and the fatty amine modified perovskite material, respectively. The TEM spectrogram shows that the prepared perovskite nanocrystal has better size distribution, the average size is 22.7nm, and the interplanar spacing is 0.29 nm; according to the XRD spectrogram, the perovskite material prepared in the example 1 has a cubic crystal structure as well as the perovskite material modified by the aliphatic amine ligand.
FIG. 3 is a calcium complex of the perovskite material prepared in example 1 and a conventional aliphatic amine ligandThe stability of the titanium ore material in the air under the continuous excitation of the laser. The invention purifies two perovskite materials to obtain solid perovskite materials, and the solid perovskite materials have the relative humidity of 38 percent at the air temperature of 25 ℃ and the air temperature of 440nm and the relative humidity of 10w/cm2The stability of both materials was tested under excitation of excitation light. Tests show that the non-protonized ligand modified perovskite material prepared in example 1 can effectively improve the stability of continuous excitation under 440nm excitation light, and only attenuates by 5.8% in 140 hours, while the perovskite material modified by aliphatic amine ligands has already attenuated by 80% in 29 hours.
Fig. 4 shows the stability of the conventional aliphatic amine ligand-modified perovskite material and the perovskite material prepared in example 1 in water under the continuous laser excitation. According to the invention, two perovskite materials are respectively immersed into deionized water after being purified to obtain solid perovskite materials, and are continuously excited by 440nm laser, after being continuously excited for 40 hours, the perovskite prepared in the embodiment 1 can still keep 75% of photoluminescence intensity, and the perovskite material modified by aliphatic amine ligand is attenuated by 80% in 10 hours. Therefore, the perovskite material modified by the non-protonized ligand has better hydrophobicity and stronger coordination property, and the surface of the perovskite material can be effectively protected.
FIG. 5 is a thermal stability curve of the perovskite prepared in example 1 under 440nm excitation light. According to the invention, the solid obtained by purifying the perovskite material in the embodiment 1 is placed on a heating table, and a heating test shows that the solid can still keep good light stability at 65 ℃ and can be obviously quenched after 85 ℃.
EDS (energy dispersive spectroscopy) elemental analysis comparison of the perovskite prepared in example 1 and the perovskite material modified by the aliphatic amine ligand is carried out, and as shown in FIG. 6, the perovskite material with a lead-rich surface is prepared in the example. FIG. 7 of perovskite and reactive precursors prepared in example 131P NMR (liquid Nuclear magnetic resonance) testing indicated that the perovskite material prepared in this example had a resonance signal at 50.7ppm, a chemical shift of 1.72ppm compared to tri-n-octylphosphine oxide, and tri-n-octylphosphine at-31.2 ppmThe resonance signal disappeared, indicating that tri-n-octylphosphine was completely converted to trioctylphosphine oxide during the reaction. Although it is used for31The presence of organic phosphorus oxide was shown by P NMR test, but it could not be said that tri-n-octylphosphine oxide was bonded to the perovskite surface, and no signal of P element was detected by XPS test, so it was considered that tri-n-octylphosphine oxide had weak interaction with the surface and was adsorbed on the perovskite surface. FIG. 8C-1 s XPS of perovskites prepared according to the invention have a COO at 288.4eV-The peak indicates that the surface of the prepared perovskite nanocrystal is modified by carboxylate. The IR spectrum in FIG. 9 of example 1 was 1532cm-1And 1418cm-1Asymmetric and symmetric telescopic vibration absorption peaks of carboxylate radical exist at 1107cm-1There is an absorption peak obtained by shifting a weaker P ═ O bond. From the above, it can be known that the perovskite prepared by the present embodiment is a perovskite nano material with a lead-rich surface and modified by carboxylate radical.
The prepared material is mixed with polymethyl methacrylate to prepare a film to test the stability of the film on a blue light LED (a 454nm GaN blue light LED is used as an excitation light source), and as shown in FIG. 10, the 100% luminous intensity can be basically kept unchanged after 75 hours under the continuous excitation of 100mW power.
Example 2: high-stability all-inorganic CsPbBr prepared from lead oleate precursor3Perovskite materials
In the embodiment, the organic divalent metal carboxylate is lead oleate, and the other steps are the same as those in embodiment 1 except for the lead oleate precursor in the preparation process of the perovskite material.
Preparing a lead oleate precursor: mixing 0.558g of PbO with 1.9ml of oleic acid and 40ml of Octadecene (ODE) solution at room temperature, adding the mixture into a 100ml three-neck flask, vacuumizing for 15 minutes under the stirring of magnetons at the rotating speed of 500 revolutions per minute until no bubbles are generated in the mixed solution, introducing nitrogen, keeping stirring and nitrogen atmosphere, heating the solution to 120 ℃ within 5 minutes, keeping the temperature at 120 ℃ for heating and vacuumizing for 30 minutes to remove water vapor until no bubbles are generated in the mixed solution, introducing nitrogen, keeping stirring and nitrogen atmosphere, heating to 150 ℃ within 5 minutes, continuously heating at 150 ℃ until PbO and oleic acid completely react to form a clear solution, and cooling to room temperature to obtain a lead oleate solution.
Example 3: preparation of zinc laurate precursor for preparing all-inorganic CsPbBr with good stability and zinc-enriched surface3A material.
The zinc laurate used in this example was commercially available zinc laurate powder, and the rest of the procedure was the same as in example 1.
Example 4: preparation of all-inorganic CsPbI with good stability and zinc-rich surface by zinc stearate precursor3A material.
The zinc stearate used in this example was commercially available zinc stearate powder, and the remaining steps were the same as in example 1.
Example 5: high-stability all-inorganic CsPbBr with lead-rich surface prepared by lead stearate precursor3Perovskite materials
The procedure of this example was the same as example 1, except that stearate-modified CsPbBr was prepared in the third step3When perovskite nanocrystalline is used, 0.188mmol of lead bromide, 5mL of ODE solution, 0.3mL of tri-n-octylphosphine solution and 0.1mmol of lead stearate are mixed and added into a 25 mL three-neck flask at room temperature, vacuum pumping is carried out for 15 minutes under the condition of magneton stirring at the rotating speed of 500 revolutions per minute until no bubbles are generated in the mixed solution, nitrogen is introduced, the temperature is raised to 120 ℃ within 5 minutes, vacuum pumping is carried out for 30 minutes at 120 ℃ until no bubbles are generated in the mixed solution, nitrogen is introduced, the temperature is raised to 160 ℃ within 5 minutes, and the temperature is maintained at 160 ℃ for continuous heating for 15-30 minutes. Heating cesium oleate at room temperature to a clear solution at 100 ℃, quickly injecting 0.4mL of cesium oleate into a three-neck flask, removing a heating device after reacting for 30 seconds, and quickly cooling the reaction solution to room temperature in an ice bath to obtain the perovskite nanocrystal with rich metal lead surface, wherein organic carboxylate and metal ions on the perovskite surface are coordinated.
Example 6: this example prepares CsPbxSn1-xI3Perovskite materials
The steps of this example are the same as those of example 5, except that gold is selected in this exampleThe metal halide is PbI2And SnI2The nonpolar organic solution is xylene, the metal halide, the nonpolar organic solution, the organic carboxylate and the organic phosphorus solution are mixed and heated up to 120 ℃ to dissolve the metal halide, and the Cs cation solution is injected at the temperature.
The embodiment can show that the perovskite material with the metal-rich surface modified by the carboxylate ligands with strong binding force is a perovskite material with the metal-rich surface, the use of aliphatic amine ligands is avoided, the problem of ligand desorption caused by protonation is effectively avoided, the perovskite material can be better protected from being decomposed by polar solvents, and the light, heat and water-oxygen stability of the material can be effectively improved.
The invention is not the best known technology.
Claims (10)
1. The perovskite material modified by the non-protonized ligand is characterized by being prepared by the reaction of organic divalent metal carboxylate and organic phosphide at high temperature, wherein carboxylate ligands are provided after the reaction of the organic divalent metal carboxylate and are combined on the surface of the perovskite, the organic phosphide is converted into organic phosphorus oxide to be adsorbed on the surface after the reaction of the organic divalent metal carboxylate, and divalent metal is enriched on the surface of the perovskite.
2. The perovskite material of claim 1, wherein the molar ratio of carboxylate to organophosphate in the organic divalent metal carboxylate is, carboxylate: organophosphates are 5:1 to 1: 3.
3. The perovskite material of claim 2, wherein the molar ratio of carboxylate to organophosphate is 1: 2.5.
4. The perovskite material of claim 1, wherein the perovskite material is a fluorescent nanomaterial crystal having a particle size of 3-50 nm.
5. The perovskite material of claim 1, wherein the material is prepared by a method comprising the steps of:
preparing a cation precursor solution of the metal Cs and an organic divalent metal carboxylate precursor;
mixing metal halide with a nonpolar organic solution and an organic phosphorus solution at room temperature, putting the mixture into a three-neck flask, heating the mixture to a temperature below the boiling point of the nonpolar organic solution and higher than 100 ℃, and continuously heating the mixture until the metal halide is completely dissolved to obtain a mixed solution; then quickly injecting a cation precursor solution of metal Cs and an organic divalent metal carboxylate precursor into the mixed solution, reacting for 30 seconds to 5 minutes, removing the heating device, and quickly cooling the reaction solution to room temperature in an ice bath to obtain a stable perovskite solution modified by the non-protonized ligand; and finally, centrifugally cleaning the solution by ethyl acetate to obtain the perovskite nano-crystal with the divalent metal-rich surface, wherein the carboxylate is coordinated with the metal ions on the surface of the perovskite.
6. The perovskite material of claim 1, wherein the material is prepared by a method comprising the steps of:
preparing a cation precursor solution of the metal Cs and an organic divalent metal carboxylate precursor;
mixing metal halide with a nonpolar organic solution, an organic phosphorus solution and an organic divalent metal carboxylate precursor at room temperature, putting the mixture into a three-neck flask, heating the mixture to a temperature below the boiling point of the nonpolar organic solution and higher than 100 ℃, and continuously heating the mixture until the metal halide is completely dissolved to obtain a mixed solution; then quickly injecting a cation precursor solution of metal Cs into the mixed solution, after the reaction is kept for 30 seconds to 5 minutes, removing the heating device, and quickly cooling the reaction solution to room temperature in an ice bath to obtain a stable perovskite solution modified by the non-protonized ligand; and finally, centrifugally cleaning the solution by ethyl acetate to obtain the perovskite nano-crystal with the divalent metal-rich surface, wherein the carboxylate is coordinated with the metal ions on the surface of the perovskite.
7. The perovskite material of claim 5 or 6, wherein the non-polar organic solution is Octadecene (ODE), octadecane, tetradecane, paraffin oil or xylene.
8. The perovskite material of claim 5 or 6, wherein the metal halide is PbCl2、PbBr2、PbI2、SnCl2、SnBr2、SnI2One or more of (a).
9. The perovskite material of claim 1, wherein the organic divalent metal carboxylate comprises dicarboxylate groups with a carbon chain length of 4 to 20, in particular comprising one or more of stearate, oleate, laurate, myristate; the divalent metal salt is one or more of lead, zinc, tin, manganese and cadmium; the organic phosphide is tri-n-octyl phosphine or tributyl phosphine.
10. The perovskite material of claim 1, wherein the high temperature reaction temperature of the organic divalent metal carboxylate and the organic phosphide is 120-220 ℃.
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| CN113105885A (en) * | 2021-04-15 | 2021-07-13 | 河北工业大学 | Perovskite/zinc oxide heterostructure luminescent material and preparation method thereof |
| CN114540024A (en) * | 2022-02-22 | 2022-05-27 | 江苏烨湫传感科技有限公司 | Perovskite quantum dot material with gas-sensitive property and application thereof |
| CN116004228A (en) * | 2022-12-26 | 2023-04-25 | 无锡极电光能科技有限公司 | Surface modified perovskite quantum dot, preparation method thereof and core-shell structure quantum dot |
| CN116004228B (en) * | 2022-12-26 | 2024-04-26 | 无锡极电光能科技有限公司 | Surface modified perovskite quantum dot, preparation method thereof and core-shell structure quantum dot |
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