Formamidinium-based calcium titanate material doped with variable valence cations and preparation method thereof

Abstract

The application relates to a formamidinium-based perovskite material based on variable valence cation doping and a preparation method thereof. The material takes formamidinium iodide and lead iodide as starting reactants, takes cobalt iodide, manganese iodide, iron iodide, cadmium iodide or antimony iodide as a dopant, is doped with variable valence metal cations through a one-step synthesis method, and stable formamidinium-based perovskite material is obtained. Compared with undoped formamidinium lead iodide, the stability of the formamidinium-based perovskite material is greatly improved, and the phase transition time is improved by two orders of magnitude, which means that the application has great significance in designing new high-efficiency and stable photoelectric conversion devices. The product size is controllable, the cost is low, the repeatability is good, the operation is simple and the like, the material can be used for in-depth research on the intrinsic properties of organic-inorganic hybrid perovskite materials, and new high-efficiency photoelectric conversion devices are further designed. The material overcomes the difficulty that the existing perovskite material has poor stability in the application process, and has higher stability compared with the perovskite material obtained by only changing the preparation method, and has good application prospect in the field of photoelectric conversion.

Description

TECHNICAL FIELD

[0001] The application relates to a formamidinium-based perovskite material based on variable valence cation doping and a preparation method thereof BACKGROUND

[0002] The application of organic-inorganic hybrid perovskite (ABX3) materials in optoelectronic materials and devices is one of the research frontiers in the field of functional materials. In the past decade, it has developed rapidly, especially in the field of photoelectric conversion. The certified efficiency of small-area devices of perovskite cells is comparable to that of monocrystalline silicon cells. The cubic phase formamidinium lead iodine perovskite (FAPbI3) material is the organic-inorganic hybrid perovskite material with the band gap closest to the Schottky limit so far (although Sn 2+ Based perovskite has a narrower optical band gap, but the device is extremely unstable, and Sn 2+ Cation is easily oxidized to Sn 4+ ). However, there are still some key bottleneck problems in the formamidinium-based perovskite thin film perovskite device: (1) the cubic phase FAPbI3 is prone to phase transition at room temperature to generate a yellow hexagonal phase with poor photoelectric conversion performance; (2) elemental Pb 0 and I 0 generated during heat treatment or light irradiation cause component segregation in the active layer; (3) residual lattice stress in the thin film increases the defect concentration and non-radiative recombination. These processes will reduce the efficiency and long-term stability of the device, and seriously restrict the development process of perovskite cells to industrialization. The traditional formamidinium perovskite cubic phase stabilization method includes the use of A-site cations (MA + , Cs + ) or X-site bromide substitution. This method can prepare a relatively stable cubic phase formamidinium-based perovskite thin film at room temperature, but the composite phase perovskite is prone to phase separation under light irradiation, causing a decrease in device efficiency. In addition, some surface / interface passivation and additive methods reported in the literature can to some extent inhibit the component segregation of the perovskite thin film or reduce the residual internal stress of the thin film, but the effect is relatively single.

[0003] The present application proposes a formamidinium-based perovskite material based on variable valence cation doping and a preparation method thereof in view of the above bottleneck problems and research status. The research idea of the formamidinium-based hybrid perovskite thin film is induced by variable valence metal cation B-site doping to stabilize the cubic phase. The three bottleneck problems mentioned above are improved simultaneously by a single method, and a stable formamidinium-based perovskite thin film with stable structure and performance is obtained: the cubic phase stability temperature range of FAPbI3 is expanded by using heterogeneous metal ion solid solution; on the other hand, through the spontaneous oxidation-reduction reaction and size effect, Pb 0 and I 0Defects, while reducing the thin film lattice residual stress caused by lead-iodine octahedral framework distortion deformation. By studying the above-mentioned multiple effect mechanism and the influence on the photoelectric properties of the material and device, it is expected to obtain a high-efficiency and long-term environmentally stable formamidinium-based perovskite photoelectric conversion device. SUMMARY

[0004] The present application aims to provide a formamidinium-based perovskite material based on variable valence cation doping and a preparation method thereof. The material uses formamidinium iodide and lead iodide as starting reactants, uses cobalt iodide or manganese iodide or iron iodide or cadmium iodide or antimony iodide as a dopant, and obtains a stable structure and performance formamidinium-based perovskite material by one-step synthesis of variable valence metal cation doping. The stability of the formamidinium-based perovskite material described in the present application is greatly improved compared to the undoped formamidinium-based lead iodide, and the phase transition time is improved by two orders of magnitude, which means that the present application has great significance in designing new high-efficiency and stable photoelectric conversion devices. The product size is controllable, the cost is low, the repeatability is good, and the operation is simple, which can be used for in-depth study of the intrinsic properties of organic-inorganic hybrid perovskite materials and further design of new high-efficiency photoelectric conversion devices.

[0005] The formamidinium-based perovskite material based on variable valence cation doping has a cubic phase structure, uses formamidinium iodide and lead iodide as starting reactants, uses cobalt iodide, manganese iodide, iron iodide, cadmium iodide or antimony iodide as a dopant, and synthesizes the formamidinium-based perovskite material by one-step synthesis method. The specific operation is carried out according to the following steps:

[0006] a. Put formamidinium iodide in a sample bottle according to a molar ratio of 1:1, and mix iodide lead with manganese iodide, cobalt iodide, iron iodide, chromium iodide or antimony iodide evenly to obtain a mixture;

[0007] b. Add a γ-butyrolactone solution to the mixture obtained in step a according to a mass ratio of 1:1, stir evenly to obtain a mixed solution, wherein the mass concentration of the γ-butyrolactone solution in the mixed solution is 50%;

[0008] c. Stir the mixed solution obtained in step b magnetically for 30 min to make it completely dissolved into a transparent and clear solution, and then perform a reaction in a constant temperature drying oven, wherein the reaction temperature is 110-130 DEG C and the reaction time is 6-10 min;

[0009] d. Pick out the small single crystal which is relatively regular and well-crystallized from the solution after the reaction in step c; and stir the remaining solution and the single crystal together at a temperature of 50-70 DEG C until it is clear and transparent;

[0010] e, the single crystal obtained in step d is added to the uniform solution in step c, and the reaction is carried out in a constant temperature drying box, the reaction temperature is 70-90℃, and the reaction time is 48-96h, so that the formamidinium-based perovskite material is obtained.

[0011] A preparation method of a formamidinium-based perovskite material based on variable valence cation doping is carried out in the following steps:

[0012] a, iodinated formamidinium is placed in a sample bottle in a molar ratio of 1:1, and lead iodide and manganese iodide, lead iodide and cobalt iodide, lead iodide and iron iodide, lead iodide and chromium iodide, or lead iodide and antimony iodide are mixed uniformly to obtain a mixture;

[0013] b, the mixture obtained in step a is added with a γ-butyrolactone solution in a mass ratio of 1:1, and stirred uniformly to obtain a mixed solution, wherein the mass concentration of the γ-butyrolactone solution in the mixed solution is 50%;

[0014] c, the mixture obtained in step b is magnetically stirred for 30min to completely dissolve into a transparent and clear solution to form a uniform solution, and then the reaction is carried out in a constant temperature drying box, the reaction temperature is 110-130℃, and the reaction time is 6-10min;

[0015] d, the small single crystals which are relatively regular and well crystallized are picked out after the reaction in step c, and the remaining solution and the single crystals are stirred at a temperature of 50-70℃ until clear and transparent;

[0016] e, the single crystal obtained in step d is added to the uniform solution in step c, and the reaction is carried out in a constant temperature drying box, the reaction temperature is 70-90℃, and the reaction time is 48-96h, so that the formamidinium-based perovskite material is obtained.

[0017] A formamidinium-based perovskite material based on variable valence cation doping, which is a cubic phase structure, takes iodinated formamidinium and lead iodide as starting reactants, takes cobalt iodide, manganese iodide, iron iodide, cadmium iodide or antimony iodide as a dopant, and synthesizes the formamidinium-based perovskite material by a one-step synthesis method, and the specific operation is carried out in the following steps:

[0018] a, 0.005-0.01mol iodinated formamidinium is placed in a sample bottle, and 0.005-0.01mol lead iodide and manganese iodide or lead iodide and cobalt iodide or lead iodide and iron iodide or lead iodide and chromium iodide or lead iodide and antimony iodide are mixed uniformly to obtain a mixture, wherein the molar ratio of iodinated formamidinium to metal iodide is 1:1;

[0019] b. Adding 3.165-6.33 g of γ-butyrolactone solution to the mixture obtained in step a. in a mass ratio of 1:1, stirring uniformly to obtain a mixture, wherein the mass concentration of γ-butyrolactone solution, methylcarbamate iodide and metal iodide in the solution is 50% respectively;

[0020] c. Magnetically stirring the mixture obtained in step b. for 30 min to completely dissolve into transparent and clear, forming a uniform solution, and then performing reaction in a constant temperature drying oven, the reaction temperature is 110-130°C, and the reaction time is 6-10 min;

[0021] d. Picking out the small single crystals which are relatively regular and well crystallized from the solution after reaction in step c., and stirring the remaining solution and single crystals together at a temperature of 50-70°C until clear and transparent;

[0022] e. Adding the single crystals obtained in step d. into the uniform solution in step c., and performing reaction in a constant temperature drying oven, the reaction temperature is 70-90°C, and the reaction time is 48-96 h, to obtain methylcarbamate perovskite material.

[0023] A preparation method of methylcarbamate perovskite material based on variable valence cation doping, which is performed according to the following steps:

[0024] a. Placing 0.005-0.01 mol of methylcarbamate iodide in a sample bottle according to a molar ratio of 1:1, and adding 0.005-0.01 mol of lead iodide mixed with manganese iodide or lead iodide mixed with cobalt iodide or lead iodide mixed with iron iodide or lead iodide mixed with chromium iodide or lead iodide mixed with antimony iodide uniformly to obtain a mixture;

[0025] b. Adding 3.165-6.33 g of γ-butyrolactone solution to the mixture obtained in step a. in a mass ratio of 1:1, stirring uniformly to obtain a mixture, wherein the mass concentration of γ-butyrolactone solution, methylcarbamate iodide and metal iodide in the solution is 50% respectively;

[0026] c. Magnetically stirring the mixture obtained in step b. for 30 min to completely dissolve into transparent and clear, forming a uniform solution, and then performing reaction in a constant temperature drying oven, the reaction temperature is 110-130°C, and the reaction time is 6-10 min;

[0027] d. Picking out the small single crystals which are relatively regular and well crystallized from the solution after reaction in step c., and stirring the remaining solution and single crystals together at a temperature of 50-70°C until clear and transparent;

[0028] e. Add the single crystal obtained in step d to the homogeneous solution in step c, and place it in a constant temperature drying oven for reaction. The reaction temperature is 70-90℃ and the reaction time is 48-96h to obtain formamidinium perovskite material.

[0029] This invention addresses the industrial demand for methods to prepare formamidinium-based perovskites based on variable-valence cation doping, providing a research approach for B-site doping of variable-valence metal cations to induce stable cubic phase formamidinium-based hybrid perovskite thin films. The single crystals synthesized using this method exhibit photoelectric properties far superior to those of widely used nanocrystalline thin-film devices.

[0030] The method for synthesizing formamidinium-based perovskites based on variable-valence cation doping in this invention is unique in the following aspects:

[0031] The single crystal growth conditions are relatively mild: the preparation of the required solution, the precipitation of the seed crystal, and the crystal growth are all carried out at a low temperature. The requirements for the growth container are low. The entire growth process can be carried out in a beaker without the need for a customized complex diffusion container.

[0032] The structure, internal defects, and residual stress of formamidinium-based perovskite mineral phases were controlled and optimized by using variable valence cation doping.

[0033] The required solution is simple and the cost is low: the solution used in this paper is a conventional solution prepared by spin coating, which does not contain other impurity groups; Attached Figure Description

[0034] Figure 1 The images show the XRD patterns of FAPbI3 doped with different proportions of Mn according to the present invention, where (a) is the XRD pattern after being placed at room temperature for 20 min, and (b) is a magnified view of the part circled in (a).

[0035] Figure 2 The samples of this invention were placed at room temperature and relative humidity of 30%-80% for 24 hours. The left side is the undoped sample, and the right side is the sample from Example 2. Detailed Implementation

[0036] Example 1

[0037] a. Place 0.005 mol of formamidine iodide in a sample vial at a molar ratio of 1:1, and add 0.005 mol of PbI. 2(0.995) FeI 2(0.005) Mix thoroughly to obtain a mixture;

[0038] b. Add 3.161g of γ-butyrolactone solution to the mixture obtained in step a at a mass ratio of 1:1, stir evenly to obtain a mixed solution, wherein the γ-butyrolactone solution accounts for 50% of the mass concentration of formamidine iodide, lead iodide and iron iodide in the mixed solution;

[0039] c. The mixture obtained in step b is stirred magnetically for 30 min to completely dissolve into transparent and clear, forming a uniform solution, and then the reaction is carried out in a constant temperature drying oven, the reaction temperature is 110°C, and the reaction time is 6 min;

[0040] d. The small single crystal which is relatively regular and well crystallized is picked out after the reaction in step c, and the remaining solution and the single crystal are stirred at a temperature of 50°C until clear and transparent;

[0041] e. The single crystal obtained in step d is added to the uniform solution in step c, and the reaction is carried out in a constant temperature drying oven, the reaction temperature is 70°C, and the reaction time is 48 h, to obtain a formamidinium-based perovskite material.

[0042] The obtained product is a regular single crystal, the phase transition time is 48 h under the condition of room temperature and air relative humidity of 30-80%, and the undoped sample is 15 min.

[0043] Example 2

[0044] a. 0.005 mol of formamidinium iodide is placed in a sample bottle according to a molar ratio of 1:1, 0.005 mol of PbI 2(0.995) MnI 2(0.005) is added, and the mixture is uniformly mixed to obtain a mixture;

[0045] b. 3.161 g of γ-butyrolactone solution is added to the mixture obtained in step a according to a mass ratio of 1:1, and stirred uniformly to obtain a mixed solution, wherein the mass concentration of γ-butyrolactone solution in the mixed solution of formamidinium iodide and lead iodide and manganese iodide is 50%;

[0046] c. The mixed solution obtained in step b is stirred magnetically for 30 min to completely dissolve into transparent and clear, forming a uniform solution, and then the reaction is carried out in a constant temperature drying oven, the reaction temperature is 130°C, and the reaction time is 10 min;

[0047] d. The small single crystal which is relatively regular and well crystallized is picked out after the reaction in step c, and the remaining solution and the single crystal are stirred at a temperature of 70°C until clear and transparent;

[0048] e. The single crystal obtained in step d is added to the uniform solution in step c, and the reaction is carried out in a constant temperature drying oven, the reaction temperature is 90°C, and the reaction time is 96 h, to obtain a formamidinium-based perovskite material.

[0049] The obtained product is a regular single crystal, the phase transition time is 53 h under the condition of room temperature and air relative humidity of 30-80%, and the undoped sample is 15 min, the XRD spectrum is attached Figure 1 , and the optical photograph is attached Figure 2 .

[0050] Example 3

[0051] a, 0.005 mol of formamidinium iodide was placed in a sample bottle, 0.005 mol of PbI 2(0.995) CoI 2(0.005) mixed uniformly to obtain a mixture;

[0052] b, 3.161 g of γ-butyrolactone solution was added to the mixture obtained in step a according to a mass ratio of 1:1, and stirred uniformly to obtain a mixed solution, wherein the mass concentration of the γ-butyrolactone solution in the mixed solution of formamidinium iodide and lead iodide and cobalt iodide was 50%;

[0053] c, the mixed solution obtained in step b was magnetically stirred for 30 min to completely dissolve into a transparent and clear solution to form a uniform solution, and then reacted in a constant temperature drying oven, the reaction temperature was 115°C, and the reaction time was 7 min;

[0054] d, the relatively regular and crystalline small single crystals precipitated after the reaction in step c were picked out; and the remaining solution and single crystals were stirred at a temperature of 55°C until clear and transparent;

[0055] e, the single crystals obtained in step d were added to the uniform solution in step c, and reacted in a constant temperature drying oven, the reaction temperature was 80°C, and the reaction time was 56 h, to obtain a formamidinium-based perovskite material.

[0056] The obtained product was a regular single crystal, and the phase transition time was 42 h under the condition of room temperature and air relative humidity of 30-80%, and the phase transition time of the undoped sample was 15 min.

[0057] Example 4

[0058] a, 0.005 mol of formamidinium iodide was placed in a sample bottle, 0.005 mol of PbI 2(0.995) CrI 2(0.005) mixed uniformly to obtain a mixture;

[0059] b, 3.161 g of γ-butyrolactone solution was added to the mixture obtained in step a according to a mass ratio of 1:1, and stirred uniformly to obtain a mixed solution, wherein the mass concentration of the γ-butyrolactone solution in the mixed solution of formamidinium iodide and lead iodide and chromium iodide was 50%;

[0060] c, the mixed solution obtained in step b was magnetically stirred for 30 min to completely dissolve into a transparent and clear solution to form a uniform solution, and then reacted in a constant temperature drying oven, the reaction temperature was 120°C, and the reaction time was 8 min;

[0061] d, pick out the small single crystal which is more regular and crystalline from the solution after reaction in step c; and stir the rest of the solution and the single crystal together at the temperature of 60 °C until it is clear and transparent;

[0062] e, add the single crystal obtained in step d to the uniform solution in step c, and place it in a constant temperature drying box for reaction, the reaction temperature is 80 °C, and the reaction time is 72 h, so that the formamidinium-based perovskite material is obtained.

[0063] The obtained product is a regular single crystal, and the phase change time is 60 h under the condition of room temperature and air relative humidity of 30-80%, and the phase change time of the undoped sample is 15 min.

[0064] Example 5

[0065] a, 0.005 mol of formamidinium iodide is placed in a sample bottle according to the molar ratio of 1:1, and 0.005 mol of PbI 2(0.995) SbI 2(0.005) mixed uniformly to obtain a mixture;

[0066] b, 3.161 g of γ-butyrolactone solution is added to the mixture obtained in step a according to the mass ratio of 1:1, and stirred uniformly to obtain a mixed solution, wherein the mass concentration of the γ-butyrolactone solution in the mixed solution of formamidinium iodide and lead iodide and antimony iodide is 50%;

[0067] c, the mixture obtained in step b is magnetically stirred for 30 min to completely dissolve into a transparent and clear solution to form a uniform solution, and then reaction is carried out in a constant temperature drying box, the reaction temperature is 125 °C, and the reaction time is 9 min;

[0068] d, pick out the small single crystal which is more regular and crystalline from the solution after reaction in step c; and stir the rest of the solution and the single crystal together at the temperature of 65 °C until it is clear and transparent;

[0069] e, add the single crystal obtained in step d to the uniform solution in step c, and place it in a constant temperature drying box for reaction, the reaction temperature is 85 °C, and the reaction time is 84 h, so that the formamidinium-based perovskite material is obtained.

[0070] The obtained product is a regular single crystal, and the phase change time is 60 h under the condition of room temperature and air relative humidity of 30-80%, and the phase change time of the undoped sample is 15 min.

Claims

1. A formamidinium-based perovskite material based on variable valence cation doping, characterized in that: The material is a cubic phase structure, and the formamidinium-based perovskite material is synthesized by a one-step synthesis method with formamidinium iodide and lead iodide as starting reactants and cobalt iodide, manganese iodide, iron iodide, cadmium iodide or antimony iodide as dopants, and the specific operation is performed according to the following steps: a. Put formamidinium iodide into a sample bottle according to a molar ratio of 1:1, and mix lead iodide with manganese iodide, lead iodide with cobalt iodide, lead iodide with iron iodide, lead iodide with chromium iodide or lead iodide with antimony iodide uniformly to obtain a mixture; b. Add a γ-butyrolactone solution to the mixture obtained in step a according to a mass ratio of 1:1, stir uniformly to obtain a mixed solution, and the mass concentration of the γ-butyrolactone solution in the mixed solution is 50%; c. Stir the mixed solution obtained in step b magnetically for 30 min to completely dissolve into a transparent and clear solution, form a uniform solution, and then perform a reaction in a constant-temperature drying box, the reaction temperature is 110-130 DEG C, and the reaction time is 6-10 min; d. Pick out small single crystals which are relatively regular and well-crystallized from the solution after the reaction in step c, and stir the remaining solution and the single crystals together at a temperature of 50-70 DEG C until the solution is clear and transparent; e. Add the single crystals obtained in step d to the uniform solution in step c, and perform a reaction in a constant-temperature drying box, the reaction temperature is 70-90 DEG C, and the reaction time is 48-96 h, to obtain the formamidinium-based perovskite material.

2. A method for preparing a formamidinium-based perovskite material doped with variable valence cations, characterized in that The following steps are performed: a. Put formamidinium iodide into a sample bottle according to a molar ratio of 1:1, and mix lead iodide with manganese iodide, lead iodide with cobalt iodide, lead iodide with iron iodide, lead iodide with chromium iodide or lead iodide with antimony iodide uniformly to obtain a mixture; b. Add a γ-butyrolactone solution to the mixture obtained in step a according to a mass ratio of 1:1, stir uniformly to obtain a mixed solution, and the mass concentration of the γ-butyrolactone solution in the mixed solution is 50%; c. Stir the mixed solution obtained in step b magnetically for 30 min to completely dissolve into a transparent and clear solution, form a uniform solution, and then perform a reaction in a constant-temperature drying box, the reaction temperature is 110-130 DEG C, and the reaction time is 6-10 min; d. Pick out small single crystals which are relatively regular and well-crystallized from the solution after the reaction in step c, and stir the remaining solution and the single crystals together at a temperature of 50-70 DEG C until the solution is clear and transparent; e. Add the single crystals obtained in step d to the uniform solution in step c, and perform a reaction in a constant-temperature drying box, the reaction temperature is 70-90 DEG C, and the reaction time is 48-96 h, to obtain the formamidinium-based perovskite material.

Images