Perovskite material, perovskite thin film, optoelectronic device and method of preparation thereof

Abstract

The application discloses a perovskite material, a perovskite thin film, an optoelectronic device and a preparation method thereof, and the chemical general formula of the perovskite material is A'(A x B 1‑x )Pb n X 3n+1 , wherein A' is at least one of a diamino organic molecule, A is methylamine CH3NH3 + , formamidine CH(NH2)2 + , B is Rb + , X is a halogen ion, x is less than 1, and n is a positive integer. The perovskite material is formed by doping Rb + and a long-chain diamino organic molecule to form an organic-inorganic doped perovskite material, and can be applied to the preparation of a perovskite light-emitting layer in an optoelectronic device such as a light-emitting diode. Based on the introduction of Rb + and the diamino organic molecule in the perovskite material, the working life and stability under a current working state can be effectively prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optoelectronic devices, and in particular to a perovskite material, a perovskite film, an optoelectronic device and a preparation method thereof. BACKGROUND

[0002] Perovskite materials have attracted worldwide attention due to their advantages such as few deep level defects, excellent optoelectronic properties, high quantum yield, easily adjustable band gap, long carrier lifetime and high mobility, and solution processing and low cost, and are widely used in light emitting diodes. Although the external quantum efficiency of perovskite light emitting diodes has been significantly improved, the short light emitting lifetime and poor device stability caused by ion migration and other shortcomings seriously hinder the development and application of perovskite light emitting diodes. SUMMARY

[0003] The present application aims to at least solve one of the problems in the prior art. To this end, the present application provides a perovskite material, a perovskite film, a light emitting diode and a preparation method thereof.

[0004] In a first aspect, the present application provides a perovskite material, the chemical formula of which is A'(A x B 1-x )Pb n X 3n+1 , wherein A' is a diamino organic molecule, A is at least one of CH3NH3⁺ (i.e. MA) and CH(NH2)2⁺ (i.e. FA); B is Rb + ; X is a halogen ion; x is less than 1, and n is a positive integer.

[0005] According to the perovskite material of the present application, at least the following advantages are achieved: the perovskite material is formed by doping Rb⁺ and long-chain diamino organic molecules to form an organic-inorganic doped perovskite material, which can be applied to perovskite light emitting devices such as light emitting diodes to form a perovskite film layer as a light emitting layer. Based on the introduction of inorganic cation Rb⁺ in the perovskite material, on the one hand, the crystallinity of the perovskite film layer can be improved, the perovskite phase structure can be stabilized, the crystal structure stability can be improved, the defect concentration can be reduced, and the light emitting performance of the perovskite light emitting device can be effectively improved. On the other hand, the ion movement phenomenon in the perovskite film layer can be well inhibited, and the working life under current working state can be effectively prolonged. The introduction of long-chain diamino organic molecules can also improve the humidity stability of the device. Therefore, the above perovskite material can significantly improve the lifetime and stability of light emitting devices such as light emitting diodes.

[0006] In some embodiments of the present invention, the perovskite material is a Dion-Jacobson type perovskite material. Dion-Jacobson type perovskite material can also further improve the stability of the device.

[0007] In some embodiments of the present invention, X is selected from Cl - Br - , I - At least one of .

[0008] A second aspect of the present invention provides a perovskite film comprising any of the perovskite materials described in the first aspect of the present invention. Methods for preparing the perovskite film include, but are not limited to, spin coating, doctor blade coating, slot extrusion, evaporation, chemical vapor deposition, coating, and screen printing.

[0009] In a third aspect of the present invention, one or more methods for preparing perovskite thin films are provided, comprising the following steps:

[0010] S11, mixing raw materials including AX, RbX, PbX2 and diamino organic molecules with an organic solvent to prepare a perovskite precursor solution; A in the AX is at least one of CH3NH3⁺ (methylamine ion) and CH(NH2)2⁺ (formamidine ion), and X in the AX, RbX and PbX2 is independently selected from halogen ions (such as Cl - Br - , I - );

[0011] S12, coating the perovskite precursor solution on the surface of the substrate to form a wet film, and then performing annealing treatment to obtain a perovskite thin film.

[0012] In some embodiments of the present invention, in step S11, the raw materials also include a defect passivator. The defect passivator can be at least one of 5-aminovaleric acid iodine (5-AVAI), polyetheramine, 4-fluorophenylmethylammonium trifluoroacetate (FPMATFA), polyethylene glycol (PEG), 5-pentanoic acid iodine (5-AVAI), 2,2'-iminodibenzoic acid (IDA), dithienobenzodithienyl p-conjugated polymer (PDTBDT-FBT), and cuprous iodide-thiourea complex (Cu(Tu)I). The addition of the defect passivator improves the luminescence efficiency of the perovskite film. The perovskite precursor solution can be prepared by first dissolving AX, RbX, PbX2, and a diamino organic molecule in an organic solvent, then adding a certain amount of the defect passivator and stirring the mixture until completely dissolved. The molar ratio of the defect passivator to lead (Pb) can be controlled to be between 0.2 and 0.4:1. The luminescence color and luminescence efficiency of the perovskite film can be regulated by adjusting the molar ratio of AX, RbX, PbX2 and diamino organic molecules, and the dosage ratio of the raw materials can be controlled as needed.

[0013] In some embodiments of the present invention, in step S11, the organic solvent is selected from at least one of N,N-dimethylformamide, dimethyl sulfoxide, and γ-butyrolactone.

[0014] A fourth aspect of the present invention provides an optoelectronic device comprising any of the perovskite thin films provided in the second aspect of the present invention, or a perovskite thin film produced by any of the perovskite thin film preparation methods provided in the third aspect of the present invention. The optoelectronic device may be a light-emitting diode, a battery, a photodetector, or the like.

[0015] In some embodiments of the present invention, the optoelectronic device is a light-emitting diode, which further includes a transparent conductive electrode, an electron injection layer, a cathode modification layer, a hole injection layer, an electrode modification layer and a metal electrode stacked in sequence; the perovskite film is sandwiched between the cathode modification layer and the hole injection layer.

[0016] In some embodiments of the present invention, the light emitting diode is in an upright structure.

[0017] In some embodiments of the present invention, the material of the electron injection layer is selected from at least one of zinc oxide (ZnO), titanium oxide (TiO2), tin oxide (SnO2), fullerene derivatives (PCBM), 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi), and 3,3'-[5'-[3-(3-pyridyl)phenyl][1,1':3',1"-terphenyl]-3,3"-diyl]dipyridine (TmPyPb).

[0018] In some embodiments of the present invention, the hole injection layer is made of a material selected from poly (3, 4-ethylenedioxythiophene) - polystyrene sulfonic acid (PEDOT: PSS), nickel oxide (NiO x ), poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), poly[(9,9-dioctylfluorenyl-2,7-diyl)-CO-(4,4'-(N-(p-butylphenyl))diphenylamine)] (TFB), poly[bis(4-phenyl)(4-butylphenyl)amine] (Poly-TPD), and 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-OMeTAD).

[0019] In some embodiments of the present invention, the material of the electrode modification layer is selected from molybdenum oxide (MoO x ), tungsten oxide (WO x ), copper oxide (CuO x ) at least one of the following.

[0020] In some embodiments of the present invention, the transparent conductive electrode is indium-doped tin oxide (ITO) or fluorine-doped tin oxide (FTO).

[0021] In some embodiments of the present invention, the cathode modification layer is made of polyethoxyethyleneimine (PEIE).

[0022] In a fifth aspect of the present invention, one or more methods for preparing a light-emitting diode are provided, comprising the following steps:

[0023] S21, mixing raw materials including AX, RbX, PbX2 and diamino organic molecules with an organic solvent to prepare a perovskite precursor solution; A in the AX is at least one of CH3NH3⁺ and CH(NH2)2⁺, and X in the AX, the RbX and the PbX2 are each independently selected from a halogen ion (such as Cl - Br - , I - );

[0024] S22, sequentially preparing an electron injection layer and a cathode modification layer on the transparent conductive electrode;

[0025] S23, preparing a perovskite film on the cathode modification layer using the perovskite precursor solution;

[0026] S24, sequentially preparing a hole injection layer, an electrode modification layer, and a metal electrode on the perovskite film;

[0027] The order of step S21 and step S22 is not limited.

[0028] In step S21, a defect passivation agent can also be added to the raw material to improve the light-emitting efficiency of the perovskite film.

[0029] The preparation method of the electron injection layer and the cathode modification layer in step S22 and the preparation method of the hole injection layer in step S24 can each independently be selected from any one of a solution spin coating method, a vacuum evaporation method, a screen printing method, and a coating method.

[0030] In step 24, the electrode modification layer and the metal electrode can be prepared by evaporation, specifically, the device can be transferred to a vacuum thermal evaporation instrument, and the evaporation speed can be controlled by the power of the thermal evaporation instrument. BRIEF DESCRIPTION OF DRAWINGS

[0031] The present application will be further described below in conjunction with the accompanying drawings and examples, in which:

[0032] Figure 1 A structure schematic diagram of the light-emitting diode prepared in Example 1 of the present application;

[0033] Figure 2 A structure schematic diagram of the perovskite film in the light-emitting diode in Example 1 of the present application;

[0034] Figure 3 A curve diagram of the external quantum efficiency of the light-emitting diode in Examples 1-4 and Comparative Example 1 of the present application under different current densities;

[0035] Figure 4 A curve diagram of the electroluminescence of the light-emitting diode in Examples 1-2 and Comparative Example 1 of the present application;

[0036] Figure 5 A curve diagram of the luminous intensity of the light-emitting diode in Examples 1 and Comparative Examples 1 and 2 of the present application under an applied current density of 100 mA / cm 2 A graph of the degradation trend of the lower radiation intensity over time. DETAILED DESCRIPTION

[0037] The concept and technical effects of the present application will be described below in conjunction with examples to fully understand the purpose, features and effects of the present application. Obviously, the described examples are only a part of the examples of the present application, but not all the examples. Based on the examples of the present application, other examples obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0038] Example 1

[0039] A light-emitting diode is prepared in this example, and the preparation method thereof comprises the following steps:

[0040] S1, preparation of an ITO transparent conductive electrode, comprising: cutting an ITO transparent conductive electrode with a size of 12x12 mm2 The transparent conductive electrode ITO glass was cleaned with detergent, deionized water, acetone, isopropyl alcohol and ethanol for 15 min in sequence, and then treated with UV-ozone for 30 min;

[0041] S2. Preparation of a ZnO electron injection layer, comprising: dissolving 1.017 g of tetramethoxyammonium hydroxide pentahydrate in 10 mL of ethanol and 0.8 g of zinc acetate in 40 mL of dimethyl sulfoxide, stirring the mixture, extracting the mixture with ethyl acetate, extracting the deposited zinc oxide solid particles using a centrifuge, and then dispersing the particles in a certain amount of anhydrous ethanol; then spin-coating the zinc oxide ethanol solution on the ITO transparent conductive electrode obtained in step S1, and heat-treating the mixture on a hot plate at 180° C. for 30 minutes to form an electron injection layer on the surface of the ITO transparent conductive electrode;

[0042] S3. Preparation of a PEIE cathode modification layer, comprising: preparing a polyethoxyethyleneimine (PEIE) solution having a concentration of 3 mg / mL, wherein the solvent is methoxyethanol; spin-coating the PEIE solution on the surface of the electron injection layer using a spin coater at a rotation speed of 3000 rad / min; after spin coating, placing the sample on a hot stage at 100° C. for 10 minutes to form a cathode modification layer on the surface of the electron injection layer;

[0043] S4, preparation of perovskite light-emitting layer, including: transferring the sample treated in step S3 into a nitrogen preparation glove box; pressing CH(NH2)2 + The molar ratio of CH(NH2)2I and RbI is 1:0.2, and then dissolved in an organic solvent (N, N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 4:1) with PbI2 and hexamethylenediamine. + The molar ratio of the total molar number of Rb to Pb is 2:1, the molar ratio of hexamethylenediamine to Pb is 0.1:1, and then a defect passivator 5-aminovaleric acid iodine (5-AVAI) is added, the molar ratio of 5-AVAI to PbI2 is 0.15, and the molar concentration of PbI2 in the mixture is 0.10 mol / L. The mixture is heated and stirred under a nitrogen environment until completely dissolved to prepare a perovskite precursor solution; the perovskite precursor solution is then transferred to the surface of the cathode modification layer with a pipette, and the perovskite precursor solution is spin-coated on the surface of the cathode modification layer using a spin coater at a speed of 4000 rad / min. The sample is then placed on a hot stage and heated at 100°C for 10 minutes to obtain a perovskite film with a thickness of about 30-40 nm and a dense surface as a light-emitting layer;

[0044] S5. Preparation of a hole injection layer, comprising: dissolving poly[(9,9-dioctylfluorenyl-2,7-diyl)-CO-(4,4'-(N-(p-butylphenyl))diphenylamine)] (TFB) in a meta-xylene solvent at a concentration of 12 to 16 mg / mL and fully dissolving the TFB to obtain a TFB solution; after the perovskite film is cooled, spin coating the TFB solution on the surface of the perovskite film at a speed of 7000 rad / min to obtain a hole injection layer;

[0045] S6. Preparation of electrode modification layer and metal electrode, including: transferring the sample from the nitrogen preparation glove box to the chamber of vacuum thermal evaporation apparatus, and evacuating the chamber to a vacuum of less than 5×10 -7 Torr, and then deposited a 7nm thick molybdenum oxide electrode modification layer and a 60nm thick gold electrode in sequence to produce a light emitting diode.

[0046] The light emitting diodes prepared above are as follows Figure 1 As shown, it includes an ITO conductive transparent electrode 1, a ZnO electron injection layer 2, a PEIE cathode modification layer 3, a perovskite film 4, a TFB hole injection layer 5, a molybdenum oxide electrode modification layer 6 and a gold electrode 7 which are stacked in sequence.

[0047] Example 2

[0048] This embodiment prepares a light emitting diode, which differs from the embodiment 1 in that: this embodiment replaces the FA (i.e. CH(NH2)2 in step S4 of the embodiment 1 with + The molar ratio of ) to Rb was adjusted from 1:0.2 to 1:0.4, and the other operations were the same as in Example 1. The structural diagram of the perovskite film is shown in FIG. Figure 2 shown.

[0049] Examples 3-4

[0050] Examples 3 and 4 respectively prepared a light-emitting diode. The difference between Examples 3 and 4 and Example 1 is that in Examples 3 and 4, the molar ratios of FA (i.e., CH(NH2)2⁺) and Rb were controlled at 1:0.1 and 1:0.3, respectively. Other operations were the same as in Example 1.

[0051] Comparative Example 1

[0052] In this comparative example, a light-emitting diode was prepared. The difference between this comparative example and Example 1 is that in the preparation process of the perovskite light-emitting layer in step S4, the addition of RbI was eliminated, that is, the molar ratio of FA to Rb was 1:0. Other operations were the same as in Example 1.

[0053] Comparative Example 2

[0054] This comparative example prepares a light-emitting diode. The difference between this comparative example and Example 1 is that in the preparation process of the perovskite light-emitting layer in step S4, this comparative example uses CsI instead of RbI used in Example 1, and other operations are the same as Example 1.

[0055] Performance Testing

[0056] The performance of the light emitting diodes prepared in Examples 1 to 4 and Comparative Example 1 was tested, specifically using a spectrometer to analyze and measure the external quantum efficiency (EQE) at different current densities. The test results are as follows: Figure 3 As shown, FA:Rb represents the molar ratio of FA to Rb in the perovskite film, and FA:Rb=1:0, 1:0.1, 1:0.2, 1:0.3, and 1:0.4 represent Comparative Example 1, Example 3, Example 1, Example 4, and Example 2, respectively. Figure 3 It can be seen that when the molar ratio of FA to Rb in the perovskite film is 1:0.2, the maximum external quantum efficiency of the light-emitting diode is 17.0%; when the molar ratio of FA to Rb in the perovskite film is 1:0.4, the external quantum efficiency of the light-emitting diode is poor, with a maximum external quantum efficiency of 5.5%.

[0057] The electroluminescence of the light-emitting diodes prepared in Examples 1, 2 and Comparative Example 1 was analyzed. The test method included applying a driving voltage to the light-emitting diodes, collecting the light emitted by the light-emitting diodes using an integrating sphere, and analyzing the light intensity and wavelength using a spectrometer. The test results were as follows: Figure 4 As shown, FA:Rb represents the molar ratio of FA to Rb in the perovskite film, and FA:Rb=1:0, 1:0.2, and 1:0.4 represent Comparative Example 1, Examples 1, and 3, respectively. Figure 4 It can be seen that the emission wavelengths of the light-emitting diodes in Comparative Example 1 and Examples 1 and 2 are 805 nm, 775 nm and 740 nm, respectively, showing an obvious blue shift. It can be seen that the emission color of the perovskite film can be controlled by adjusting the molar ratio of FA and Rb in the raw materials.

[0058] The light emitting diodes prepared in Example 1 and Comparative Examples 1 and 2 were subjected to an aging test. The specific testing method included applying a current density of 100 mA / cm to the light emitting diodes. 2 The constant current is used to test the luminous intensity by integrating sphere and spectrometer. After a period of testing time, the luminous intensity drops to 50% of the initial value, which is regarded as the T50 life of the device. Then, the time it takes for the luminous intensity to drop to 50% of the initial value (i.e. T50) is measured to examine the service life and stability of the light-emitting diode. The results are shown in the figure. Figure 5As shown, FA:Rb=1:0, 1:0.2 represent Comparative Example 1 and Example 1 respectively, and FA:Cs=1:0.2 represents Comparative Example 2. Figure 5 The test results of the light emitting diodes of Comparative Examples 1 and 2 and Example 1 show that, under the same perovskite system and doping ratio, doping Rb and Cs in the perovskite material can improve the life of the light emitting diode. 2 In the aging test under the following conditions, when the radiation intensity dropped to 50% of the initial value (i.e., T50), the lifetime of the light-emitting diode in Example 1 in which rubidium ions were doped into the perovskite film (T50=48.4h) was significantly longer than the lifetime of the light-emitting diode in Comparative Example 2 in which cesium ions were doped into the perovskite film (T50=29.3h). This shows that compared with doping the perovskite material with cesium ions, doping with rubidium ions significantly improves the lifetime and stability of the film and device.

[0059] The above-described embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A method for preparing a perovskite thin film, characterized in that: The following steps are involved: S11, mixing raw materials including AX, RbX, PbX2, diamino organic molecules and defect passivator with organic solvent to prepare a perovskite precursor solution; A in AX is CH3NH3 + 、CH(NH2)2 + At least one of the above, X in the above AX, the above RbX and the above PbX2 is independently selected from halogen ions; the above diamino organic molecule is hexamethylenediamine; the molar ratio of the above defect passivator to Pb is (0.2-0.4):1; S12, coating the perovskite precursor solution on the surface of the substrate to form a wet film, and then performing annealing treatment to obtain a perovskite thin film.

2. A perovskite film, characterized in that: The perovskite film is prepared by the preparation method of the perovskite film according to claim 1.

3. An optoelectronic device, characterized in that: Comprising the perovskite thin film according to claim 2.

4. The optoelectronic device according to claim 3, wherein: The optoelectronic device is a light-emitting diode, which further includes a transparent conductive electrode, an electron injection layer, a cathode modification layer, a hole injection layer, an electrode modification layer and a metal electrode stacked in sequence; the perovskite film is sandwiched between the cathode modification layer and the hole injection layer.

5. The optoelectronic device according to claim 4, wherein: The light emitting diode is of an upright structure.

6. The optoelectronic device according to claim 4, wherein: The material of the electron injection layer is selected from at least one of zinc oxide, titanium oxide, tin oxide, fullerene derivatives, 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene, and 3,3'-[5'-[3-(3-pyridyl)phenyl][1,1':3',1"-terphenyl]-3,3"-diyl]dipyridine.

7. The optoelectronic device according to claim 4, wherein: The material of the hole injection layer is selected from at least one of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid, nickel oxide, poly[bis(4-phenyl) (2,4,6-trimethylphenyl)amine], poly[(9,9-dioctylfluorenyl-2,7-diyl)-CO-(4,4'-(N-(p-butylphenyl))diphenylamine)], poly[bis(4-phenyl)(4-butylphenyl)amine], and 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene.

8. The optoelectronic device according to claim 4, wherein: The material of the electrode modification layer is selected from at least one of molybdenum oxide, tungsten oxide and copper oxide.

9. The optoelectronic device according to claim 4, wherein: The material of the cathode modification layer is polyethoxyethyleneimine.

10. The method for preparing an optoelectronic device according to any one of claims 4 to 9, characterized in that: The following steps are involved: S1, mixing raw materials including AX, RbX, PbX2, diamino organic molecules and defect passivator with organic solvent to prepare a perovskite precursor solution; A in AX is CH3NH3 + 、CH(NH2)2 + At least one of the above, X in AX, RbX and PbX2 is independently selected from halogen ions; the diamino organic molecule is selected from hexamethylenediamine; the molar ratio of the defect passivator to Pb is (0.2-0.4):1; S2. sequentially preparing an electron injection layer and a cathode modification layer on the transparent conductive electrode; S3, preparing a perovskite film on the cathode modification layer using the perovskite precursor solution; S4, sequentially preparing a hole injection layer, an electrode modification layer and a metal electrode on the perovskite film; The order of step S1 and step S2 is not limited.

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