CN109912459B

CN109912459B - Bimetal perovskite nano material and preparation method thereof

Info

Publication number: CN109912459B
Application number: CN201910176566.2A
Authority: CN
Inventors: 戴武斌; 周佳; 许硕; 胡金; 黄珂; 徐慢
Original assignee: Wuhan Institute of Technology
Current assignee: Wuhan Institute of Technology
Priority date: 2019-03-08
Filing date: 2019-03-08
Publication date: 2021-10-12
Anticipated expiration: 2039-03-08
Also published as: CN109912459A

Abstract

The invention relates to a bimetallic perovskite nano material and a preparation method thereof, wherein the bimetallic perovskite nano material is a perovskite-structured nano material with the particle size of 10-20 nm, and the expression is FA₄Ge^ⅡSb^ⅢCl₁₂Wherein FA is NH₂CH＝NH₂ ⁺. The preparation method comprises the following steps: 1) adding antimony trioxide and germanium dichloride into a hydrochloric acid solution to prepare a mixed solution; 2) at normal temperature, formamidine chloride is added into the mixed solution obtained in the step 1), precipitation is obtained after stirring for 0.5-1h, then a glass sand core is adopted for filtering, and filter residue is subjected to reduced pressure drying to obtain a bimetallic perovskite compound powder sample. The bimetallic perovskite material provided by the invention has relatively high stability under the conditions of high humidity, long-term illumination and heating, and overcomes the defects of the conventional perovskite material; and has a lower direct band gap, which is beneficial to generating electron transition, thereby improving the photoelectric conversion efficiency.

Description

Bimetal perovskite nano material and preparation method thereof

Technical Field

The invention belongs to the technical field of perovskite solar cells, and particularly relates to a bimetallic perovskite compound FA₄Ge^ⅡSb^ⅢCl₁₂A nano material and a preparation method thereof.

Background

MAPbI has been adopted recently because of its many advantages such as high extinction coefficient, low defect state concentration and long carrier lifetime₃(MA＝CH₃NH₃ ⁺) As representative organic-inorganic hybrid halide perovskite material with higher power conversion efficiency (general formula AMX)₃A ═ organic molecule, M ═ divalent metal ion, and X ═ halide) has attracted considerable attention for use in solar cells. MAPbi₃The composite material has a wide absorption range and a direct band gap, can realize high power conversion efficiency by optimizing a cell structure when being used as a light absorber in a perovskite solar cell, but limits MAPbI₃Key problems for large-scale commercial applications of photovoltaic devices are: 1) the material is unstable under the conditions of high humidity, long-term illumination and heat, and is easy to decompose; 2) the metal ions lead ions are toxic; 3) the photovoltaic device power output is unstable.

It was found that formamidinium FA (NH) was used₂CH＝NH₂ ⁺) The substitution of methylammonium MA leads to an improvement in its chemical stability, mainly because 1) FA can form a more symmetrical crystal structure with respect to MA; 2) the smaller energy band gap allows absorption of near infrared light; 3) FA possesses a higher decomposition temperature. In addition, a similar single metal element is used instead of Pb element, such as group 14 element (Ge)²⁺Or Sn²⁺) Alkaline earth metal element (Ca)²⁺，Mg²⁺，Sr²⁺Etc.), transition metal elements (V)²⁺，Mn²⁺，Fe²⁺，Co²⁺Etc.) or p-block element (Ga)²⁺，In²⁺) Among these elements, an element which is stable in performance, non-toxic and harmless to the environment is found to replace Pb. However, most of the elements have been found to have the following problems: 1) the band gap is too high; 2) toxic or radioactive (Ge of the invention)^Ⅱ-Sb^ⅢNon-toxic and abundant in soil); 3) instability at the +2 valence state, etc., resulting in their limited ability to form perovskites or unsuitable for use in the photovoltaic field. Therefore, in the current research field, the preparation of stable and efficient lead-free perovskite materials has only been successful to a limited extent.

At present, most of the single-metal perovskites adopt the equivalent substituted (+ 2-valent) metal, so that the use of double metals for replacing the single metal can be considered, wherein the valence states of the two metals are respectively +3 and +1 or both +2, and the method can maintain the overall charge balance. However, most of the bimetallic perovskite materials synthesized at present have indirect band gaps or direct band gaps which are not suitable for the application of the materials in the photovoltaic field, so that the materials are limited.

In view of these limitations, the present invention provides a stable and highly efficient lead-free bimetallic perovskite compound FA₄Ge^ⅡSb^ⅢCl₁₂The leadless double-metal perovskite material has higher photo-thermal stability and moisture resistance, and compared with other types of solar cells, the semiconductor material FA is used₄Ge^ⅡSb^ⅢCl₁₂The prepared perovskite solar cell has higher power conversion efficiency.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a bimetallic perovskite compound FA₄Ge^ⅡSb^ⅢCl₁₂The lead-free bimetallic perovskite material has stronger photo-thermal stability and moisture resistance, and compared with other types of solar cells, FA is used₄Ge^ⅡSb^ⅢCl₁₂The perovskite solar cell prepared from the semiconductor material has higher power conversion efficiency.

In order to solve the technical problems, the technical scheme provided by the invention is as follows:

providing a bimetallic perovskite nano material, wherein the bimetallic perovskite nano material is a perovskite structure nano material with the particle size of 10-20 nm, and the expression is FA₄Ge^ⅡSb^ⅢCl₁₂Wherein FA is NH₂CH＝NH₂ ⁺。

The invention also provides a preparation method of the bimetallic perovskite nano material, which comprises the following steps:

1) antimony trioxide (Sb)₂O₃) And germanium dichloride (GeCl)₂) Adding the mixed solution into a hydrochloric acid solution to prepare a mixed solution;

2) at normal temperature, formamidine chloride is added(HC(NH₂)₂Cl) is added into the mixed solution obtained in the step 1), precipitation is obtained after stirring for 0.5-1h, then glass sand core is adopted for filtering, and the obtained filter residue is decompressed and dried to obtain the bimetallic perovskite compound FA₄Ge^ⅡSb^ⅢCl₁₂Powder samples.

According to the scheme, the concentration of the hydrochloric acid solution in the step 1) is 1.5-2.5 mol/L.

According to the scheme, the molar ratio of elements Ge in the mixed solution in the step 1): sb: and Cl is 1-2: 4-6: 10 to 20.

According to the scheme, the molar ratio of formamidine chloride in the step 2) to Ge element in the mixed solution is 0.2-0.8: 1.

according to the scheme, the reduced pressure drying condition in the step 2) is as follows: the temperature is 90-110 deg.C, drying time is 1-2h, and pressure is set below 2.67 kPa.

The invention also comprises the bimetallic perovskite compound nano-material FA₄Ge^ⅡSb^ⅢCl₁₂And preparing the obtained perovskite solar cell photovoltaic device.

The invention has the beneficial effects that: 1. the invention provides a bimetallic perovskite material FA₄Ge^ⅡSb^ⅢCl₁₂The material shows relatively high stability under the conditions of high humidity, long-term illumination and heating, and overcomes the defects of the conventional perovskite material; the material has a lower direct band gap (1.3eV), and is beneficial to generating electron transition, so that the photoelectric conversion efficiency is improved; the higher conductivity makes the material suitable for application in single-stage absorption solar cells (the invention uses FA)₄Ge^ⅡSb^ⅢCl₁₂The optimal short-circuit photocurrent density Jsc of the solar cell device prepared by perovskite material is 23.1 mA-cm^-2The open-circuit voltage Voc is 0.73eV, the FF is 0.53, and the power conversion efficiency is as high as 4.7%). 2. The invention adopts a relatively simple solution method for preparation, and uses the bimetallic germanium-antimony which is nontoxic and rich in soil to replace lead in the perovskite material of the traditional solar cell, thereby avoiding the potential pollution of the perovskite material to the environment.

Drawings

FIG. 1 shows FA prepared in example 1 of the present invention₄Ge^ⅡSb^ⅢCl₁₂The XRD pattern of the powder (a) and its standard card (b);

FIG. 2 shows FA prepared in example 1₄Ge^ⅡSb^ⅢCl₁₂SEM image of the powder;

FIG. 3 shows FA prepared in example 1₄Ge^ⅡSb^ⅢCl₁₂Absorbance and photoluminescence spectra of the powder;

FIG. 4 shows FA prepared in example 1₄Ge^ⅡSb^ⅢCl₁₂Tauc curve of the powder;

FIG. 5 shows FA prepared in example 1₄Ge^ⅡSb^ⅢCl₁₂Thermogravimetric curve of the powder;

FIG. 6 shows FA prepared in examples 1-3₄Ge^ⅡSb^ⅢCl₁₂Placing the perovskite material in a room temperature environment with the relative humidity of 60% for different time, and measuring XRD (X-ray diffraction) patterns;

FIG. 7 shows FA prepared in examples 1, 4, 5 and 6₄Ge^ⅡSb^ⅢCl₁₂XRD (X-ray diffraction) patterns of the perovskite material are measured in different illumination time and humidity environments;

FIG. 8 is a schematic structural view of a perovskite solar cell device prepared in example 7;

FIG. 9 is a J-V curve for the perovskite solar cell device prepared in example 7.

Detailed Description

In order to make the technical solutions of the present invention better understood, the present invention is further described in detail below with reference to the accompanying drawings.

Example 1

Preparation of bimetallic perovskite nano material FA₄Ge^ⅡSb^ⅢCl₁₂The method comprises the following specific steps:

1) 2.5mmol of antimony trioxide (Sb)₂O₃) And 1.5mmol germanium dichloride (GeCl)₂) Adding into 5.0mL hydrochloric acid solution (2mol/L) to prepareTo a mixed solution;

2) at room temperature, 0.5mmol of formamidine chloride (HC (NH)₂)₂Cl) is added into the mixed solution obtained in the step 1), the mixture is stirred for 1 hour at normal temperature to obtain a precipitate, then a glass sand core is adopted for filtration, and the obtained filter residue is dried under reduced pressure (after being vacuumized, the temperature is set at 100 ℃, the drying time is 1.5 hours, and the pressure is set at 2.67kPa) to obtain the bimetallic perovskite compound FA₄Ge^ⅡSb^ⅢCl₁₂Powder samples.

The XRD pattern (see FIG. 1) of the powder sample of this example was measured by an X-ray powder diffractometer (model D8Advance), which showed the same pattern as FA₄Ge^ⅡSb^ⅢCl₁₂Corresponding crystal structure.

SEM images (see FIG. 2) of the powder samples of the present example were measured by a field emission scanning electron microscope (model JEOL JSM-7600F), and the particle sizes were found to be 10-20 nm.

The absorbance and emission spectra of the powder sample of this example (see FIG. 3) were measured by a microspectrophotometer (model No. SD1200-LS-HA), and the detection wavelength range was 300-1000nm, and the absorption spectrum exhibited a broad absorption band, indicating that the powder sample had semiconductor properties. The strongest emission peak was observed at 950nm in the photoluminescence spectrum, belonging to near infrared emission, indicating that this powder sample is suitable as a light absorbing material in solar cells.

The absorption optical density of the semiconductor powder sample of this example was measured by a microspectrophotometer (model No. SD1200-LS-HA) to produce a Tauc curve to determine the band gap of the material (see fig. 4), indicating that the band gap of the sample powder is about 1.3eV, consistent with the results of fig. 3, further demonstrating that the powder material HAs a direct band gap suitable as an absorbing material in a solar cell.

The thermogravimetric curve (see fig. 5) of the powder sample is measured by a thermogravimetric analyzer (model number is SDT-Q600), and it can be seen that the material is not decomposed at the high temperature of 235 ℃, which indicates that the powder material has stronger thermal stability.

Example 2

The sample powder prepared in example 1 was placed in an environment with a relative humidity of 60% for 1 month, and then subjected to XRD performance characterization.

Example 3

The sample powder prepared in example 1 was placed in an environment with a relative humidity of 60% for 3 months and then subjected to XRD performance characterization.

XRD patterns of the powder samples of examples 1 to 3 were measured by an X-ray powder diffractometer (model D8Advance) (see FIG. 6) in which (a) is FA₄Ge^ⅡSb^ⅢCl₁₂The XRD patterns of the powder samples of example 1, example 2 and example 3 were obtained for the standard cards, (b), (c) and (d), respectively, and it can be seen that all three powder samples have the same FA₄Ge^ⅡSb^ⅢCl₁₂The corresponding crystal structure shows that the fluorescent powder is not decomposed and has stronger moisture resistance.

Example 4

The sample powder prepared in example 1 was placed in an environment with a relative humidity of 60%, irradiated with simulated sunlight for 3 days, and then subjected to XRD performance characterization.

Example 5

The sample powder prepared in example 1 was placed in an environment with a relative humidity of 60%, irradiated with simulated sunlight for 15 days, and then subjected to XRD performance characterization.

Example 6

Except that the sample powder prepared in example 1 was placed in an environment with a relative humidity of 0%, irradiated with simulated sunlight for 15 days, and then subjected to XRD performance characterization.

XRD patterns of the powder samples of example 1, example 4, example 5 and example 6 were measured by an X-ray powder diffractometer (model D8Advance) (see FIG. 7) in which (a) is FA₄Ge^ⅡSb^ⅢCl₁₂The XRD patterns of the powder samples of examples 1, 4, 5 and 6 were obtained for the standard cards, (b), (c), (d) and (e), respectively, and it can be seen that all four samples have the same FA pattern as that of FA₄Ge^ⅡSb^ⅢCl₁₂The corresponding crystal structure shows that the fluorescent powder is not decomposed and has stronger stability under the conditions of illumination and moist environment.

Example 7

The bimetallic perovskite nano material FA prepared in example 1₄Ge^ⅡSb^ⅢCl₁₂The method is applied to the solar cell to prepare the corresponding solar cell device, and comprises the following steps:

1) preparing TiO on the surface of FTO substrate₂A barrier layer;

2) the bimetallic perovskite compound FA obtained in example 1₄Ge^ⅡSb^ⅢCl₁₂Uniformly depositing the nano powder material on the substrate in 30s by a spin coating method;

3) Spiro-OMeTAD was dissolved in chlorobenzene (75mg/mL) and spin-coated on a substrate to form a good hole transport layer, and then an Au electrode was deposited on the substrate by thermal evaporation, and the prepared perovskite solar cell device was, in order from bottom to top: FTO substrate, TiO₂Barrier layer, perovskite material FA₄Ge^ⅡSb^ⅢCl₁₂And Spiro-OMeTAD and Au electrodes, and the structural schematic diagram of the prepared perovskite solar cell device is shown in FIG. 8. The J-V curve of the perovskite solar cell device was measured by a digital source meter (model number keithley 2400) (see fig. 9), and the photovoltaic parameters thereof were respectively: short circuit photocurrent density Jsc 23.1mA cm^-2The open-circuit voltage Voc is 0.73eV, the FF is 0.53, and the power conversion efficiency is as high as 4.7%.

Claims

1. Bimetallic perovskite nano material FA₄Ge^ⅡSb^ⅢCl₁₂The preparation process of (1), wherein FA is NH₂CH=NH₂ ⁺The particle size of the bimetallic perovskite nano material is 10-20 nm, and the method is characterized by comprising the following steps:

1) adding antimony trioxide and germanium dichloride into a hydrochloric acid solution to prepare a mixed solution, wherein the concentration of the hydrochloric acid solution is 2mol/L, and the molar ratio of elements Ge: sb: cl = 1.5: 5: 10;

2) adding formamidine chloride into the mixed solution obtained in the step 1) at normal temperature, wherein the formamidine chloride and the mixed solution areThe molar ratio of Ge element is 0.5: 1.5, stirring for 1h to obtain a precipitate, then filtering by adopting a glass sand core, and decompressing and drying the obtained filter residue to obtain a bimetallic perovskite compound FA₄Ge^ⅡSb^ⅢCl₁₂Powder samples, drying conditions under reduced pressure were: after vacuum pumping, drying was carried out at a temperature of 100 ℃ for 1.5 hours under a pressure of 2.67 kPa.