Precursor solution, perovskite absorber layer and perovskite solar cell

Abstract

The present invention discloses a precursor solution, a perovskite absorption layer and a perovskite solar cell, belonging to the technical field of solar cells. The precursor solution of the present invention is prepared by dissolving a solute PbX2 in a solvent, and the solvent contains at least N,N-dimethyl-3-methoxypropionamide. The present invention selects N,N-dimethyl-3-methoxypropionamide as a solvent, which can better disperse PbX2 and obtain a precursor solution with a more uniform PbX2 dispersion. After the precursor solution is annealed, the uniform surface is more easily combined with methylammonium iodide to obtain a perovskite absorption layer with uniform film formation. The perovskite absorption layer prepared by the present invention using the precursor solution has better light absorption and energy conversion efficiency.

Description

Technical Field

[0001] The present invention relates to the field of solar cells, and in particular to a precursor solution, a perovskite absorption layer and a perovskite solar cell. Background Art

[0002] Perovskite solar cells have become a research hotspot in the solar cell field due to their outstanding advantages such as high photoelectric conversion efficiency, low cost, and simple production. Among them, the perovskite absorber layer, as a key component of perovskite solar cells, affects the light absorption and conversion efficiency of the perovskite absorber layer.

[0003] In the prior art, Chinese patent CN201811020157.5 discloses a method for preparing perovskite solar cells using a ternary mixed solvent. During the preparation process of perovskite solar cells, by optimizing the solvent ratio, a ternary mixed solvent of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and γ-butyrolactone (GBL) is used for the first time to prepare the perovskite precursor solution. Compared with the previous binary mixed solvent, this greatly improves the crystallization quality of the perovskite film. The perovskite absorber layer prepared using the three solvents at this ratio increases the grain size, reduces the carrier recombination loss caused by defects at the grain boundaries, and increases the carrier lifetime, ultimately improving the photoelectric conversion efficiency of the perovskite solar cell device and improving the series and parallel resistance of the device.

[0004] Chinese patent CN202011170108.7 discloses a method for synthesizing copper-based perovskite powder using a low-temperature solvent method. The method comprises the following steps: adding CsX and CuX to a polar organic mixed solution and stirring at 40-70°C for 4-6 hours; wherein the polar organic mixed solution is a mixed solution of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), the CsX is cesium chloride, cesium bromide, or cesium iodide, and the CuX is copper chloride, copper bromide, or copper iodide.

[0005] The above scheme has been optimized in the selection of organic solvents. It can be seen that organic solvents have a significant effect on the binding and crystallization of perovskite precursors.

[0006] The difficulty in the existing technology is how to improve the photoelectric conversion efficiency by optimizing the solvent. Summary of the Invention

[0007] The object of the present invention is to provide a precursor solution, a perovskite absorption layer and a perovskite solar cell, wherein the perovskite absorption layer prepared by using the precursor solution has better light absorption and energy conversion efficiency.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] In a first aspect, the present invention provides a precursor solution, wherein the precursor solution is prepared by dissolving a solute PbX2 in a solvent;

[0010] wherein X is F, Cl, Br or I;

[0011] The solvent contains at least N,N-dimethyl-3-methoxypropionamide.

[0012] It should be understood that in the precursor solution of the present invention, the content of N,N-dimethyl-3-methoxypropionamide in the solvent is greater than 0% and less than or equal to 100%; that is, the solvent in the precursor solution includes but is not limited to N,N-dimethyl-3-methoxypropionamide.

[0013] Through repeated experiments, the inventors concluded that as the amount of N,N-dimethyl-3-methoxypropionamide in the solvent increases, the power conversion efficiency (PCE) of the perovskite absorption layer prepared from the precursor solution will increase accordingly. In other words, even the addition of a small amount of N,N-dimethyl-3-methoxypropionamide will improve the PCE.

[0014] Specifically, the present invention uses N,N-dimethyl-3-methoxypropionamide, which has a higher dipole moment and can better disperse PbX2, and can obtain a precursor solution with a more uniform dispersion of PbX2. After annealing, the precursor solution has a uniform surface that is more easily combined with methylammonium iodide to obtain a uniform film-forming perovskite absorption layer; in terms of performance, the filling factor FF and energy conversion efficiency of the uniform film-forming perovskite absorption layer are significantly improved.

[0015] Preferably, the content of N,N-dimethyl-3-methoxypropionamide in the solvent is not less than 10%, more preferably not less than 50%, based on the total weight of the solvent.

[0016] The inventors found through experiments that when the content of N,N-dimethyl-3-methoxypropionamide in the solvent is not less than 10%, the energy conversion efficiency (PCE) will be significantly improved. When the content of N,N-dimethyl-3-methoxypropionamide in the solvent is not less than 50%, the energy conversion efficiency (PCE) will be significantly improved.

[0017] When the solvent is not pure N,N-dimethyl-3-methoxypropionamide, the remaining components in the solvent are one or more combinations of amide solvents, dimethyl sulfoxide, and γ-butyrolactone.

[0018] It should be understood that the remaining components in the solvent can be an amide solvent alone, or dimethyl sulfoxide alone, or γ-butyrolactone alone; or a mixture of any two of an amide solvent, dimethyl sulfoxide, and γ-butyrolactone in any ratio; or a mixture of any three of an amide solvent, dimethyl sulfoxide, and γ-butyrolactone in any ratio.

[0019] Preferably, the amide solvent includes but is not limited to N,N-dimethylformamide, N,N-dimethylacetamide and the like.

[0020] Preferably, in the precursor solution, the concentration of the solute is 0.3-0.5 g / mL. At this concentration, the prepared perovskite absorber layer has better PCE performance.

[0021] The precursor solution of the present invention can be prepared by any suitable method known in the art. For example, the solute PbX2 is directly dissolved in N,N-dimethyl-3-methoxypropionamide, and the corresponding precursor solution can be obtained by stirring and adjusting the concentration of the solute PbX2 in the solution.

[0022] The precursor solution provided by the present invention can be prepared into a precursor film through annealing treatment.

[0023] In a second aspect, the present invention provides a perovskite absorption layer, wherein the perovskite absorption layer is prepared by coating a methylammonium iodide solution on a precursor film and then annealing the film;

[0024] Wherein, the precursor film is prepared by annealing the precursor solution described in the first aspect.

[0025] Based on the above description of the first aspect, the filling factor FF and energy conversion efficiency of the perovskite absorption layer provided by the present invention are significantly improved.

[0026] Specifically, the steps for preparing the precursor film are as follows: coating the precursor solution described in the first aspect on a substrate and then annealing the substrate.

[0027] The annealing treatment described in the present invention is a commonly used annealing treatment process in this field, and the coating in the present invention is specifically spin coating (spin coating).

[0028] Specifically, in the present invention, the spin coating speed is 2000-4000 r / min, and the spin coating time is 10-30s; the annealing temperature in the precursor film preparation step is 60-75°C, and the annealing time is 20-40min; the annealing temperature in the perovskite absorption layer preparation step is 80-90°C, and the annealing time is 20-40min.

[0029] Preferably, the thickness of the perovskite absorption layer is 350-500 nm.

[0030] Preferably, the methylammonium iodide solution is prepared by dissolving methylammonium iodide in isopropanol.

[0031] More preferably, the concentration of methylammonium iodide in the methylammonium iodide solution is 0.03-0.05 g / mL.

[0032] In a third aspect, the present invention provides a perovskite solar cell, comprising the perovskite absorption layer according to the second aspect.

[0033] Preferably, the perovskite solar cell includes a transparent conductive layer, an electron transport layer, a perovskite absorption layer, a hole transport layer and a back electrode layer.

[0034] Specifically, in the present invention: the transparent conductive layer is ITO conductive glass (indium tin oxide), and the thickness of the transparent conductive layer is 30nm-400nm.

[0035] The electron transport layer material includes but is not limited to titanium dioxide (TiO2), tin oxide (SnO2), and zinc oxide (ZnO), and the thickness of the electron transport layer is 30nm-350nm.

[0036] The hole transport material is Spiro-OMeTAD, and the thickness of the hole transport layer is 20nm-500nm.

[0037] Based on the description of the first and second aspects above, the perovskite solar cell provided by the present invention also has better light absorption and energy conversion efficiency compared with the prior art.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] In this case, N,N-dimethyl-3-methoxypropionamide is used to replace N,N-dimethylformamide (DMF) in the traditional solution. N,N-dimethyl-3-methoxypropionamide has a higher dipole moment and a greater polarity than DMF, and it dissolves metal salts more easily than DMF. In addition, the precursor solution prepared with N,N-dimethyl-3-methoxypropionamide as a solvent is stable, has a moderate viscosity, and can be retained in the atmosphere for a long time. After annealing treatment of PbX2, the uniform surface is more easily combined with methylammonium iodide to obtain a uniform film-forming perovskite absorption layer. In terms of performance, the filling factor FF and energy conversion efficiency PCE of the uniform film-forming perovskite absorption layer are significantly improved. DETAILED DESCRIPTION

[0040] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0041] It should be noted that in the embodiments of the present invention, X in PbX2 is F, Cl, Br or I; preferably iodine, but according to the records of the prior art and the experimental scheme of preparing the perovskite absorption layer by a two-step method, X can be obtained by using F, Cl, and Br to achieve the same effect as iodine.

[0042] The perovskite solar cell provided by the present invention has a formal structure.

[0043] Example 1

[0044] This embodiment provides a perovskite solar cell, which includes a transparent conductive layer, an electron transport layer, a perovskite absorption layer, a hole transport layer, and a back electrode layer; a method for preparing the perovskite solar cell includes the following steps:

[0045] Clean the ITO transparent conductive glass and perform UV-ozone treatment to a thickness of 30 nm;

[0046] The electron transport layer SnO2 was spin-coated on the ITO transparent conductive glass with a thickness of 30 nm;

[0047] The perovskite absorption layer is spin-coated on the electron transport layer SnO2 with a thickness of 350nm;

[0048] The specific preparation steps of the perovskite absorption layer are as follows:

[0049] PbI2 was dissolved in N,N-dimethyl-3-methoxypropionamide to obtain solution A, and methylammonium iodide was dissolved in isopropanol to obtain solution B; the concentration of PbI2 in solution A was 400 mg / mL; the concentration of methylammonium iodide in solution B was 40 mg / mL;

[0050] Solution A was spin-coated on the electron transport layer SnO2 and annealed to obtain a PbI2 thin film; the spin-coating speed was 3000 r / min and the spin-coating time was 20 s; the annealing temperature was 70 ° C and the annealing time was 30 min;

[0051] Solution B was spin-coated on the PbI2 film and annealed to obtain a perovskite absorption layer (thickness 350 nm); the spin-coating speed was 3000 r / min and the spin-coating time was 20 s; the annealing temperature was 90 ° C and the annealing time was 30 min;

[0052] The hole transport layer spiro-OMeTAD was prepared by spin coating on the perovskite absorber layer with a thickness of 100 nm.

[0053] An Au back electrode layer with a thickness of 100 nm was prepared by vapor deposition on the hole transport layer to obtain a perovskite solar cell.

[0054] Example 2

[0055] This embodiment provides a perovskite solar cell, which includes a transparent conductive layer, an electron transport layer, a perovskite absorption layer, a hole transport layer, and a back electrode layer; a method for preparing the perovskite solar cell includes the following steps:

[0056] Clean the ITO transparent conductive glass and perform UV-ozone treatment to a thickness of 30 nm;

[0057] The electron transport layer SnO2 was spin-coated on the ITO transparent conductive glass with a thickness of 30 nm;

[0058] The perovskite absorption layer is spin-coated on the electron transport layer SnO2 with a thickness of 500nm;

[0059] The specific preparation steps of the perovskite absorption layer are as follows:

[0060] PbI2 was dissolved in N,N-dimethyl-3-methoxypropionamide to obtain solution A, and methylammonium iodide was dissolved in isopropanol to obtain solution B; the concentration of PbI2 in solution A was 300 mg / mL; the concentration of methylammonium iodide in solution B was 50 mg / mL;

[0061] Solution A was spin-coated on the electron transport layer SnO2 and annealed to obtain a PbI2 thin film; the spin-coating speed was 4000 r / min and the spin-coating time was 30 s; the annealing temperature was 70°C and the annealing time was 30 min;

[0062] Solution B was spin-coated on the PbI2 film and annealed to obtain a perovskite absorption layer (thickness 500 nm); the spin-coating speed was 4000 r / min and the spin-coating time was 30 s; the annealing temperature was 90° C. and the annealing time was 30 min.

[0063] The hole transport layer spiro-OMeTAD was prepared by spin coating on the perovskite absorber layer with a thickness of 100 nm.

[0064] An Au back electrode layer with a thickness of 100 nm was prepared by vapor deposition on the hole transport layer to obtain a perovskite solar cell.

[0065] Example 3

[0066] This embodiment provides a perovskite solar cell, which includes a transparent conductive layer, an electron transport layer, a perovskite absorption layer, a hole transport layer, and a back electrode layer; a method for preparing the perovskite solar cell includes the following steps:

[0067] Clean the ITO transparent conductive glass and perform UV-ozone treatment to a thickness of 30 nm;

[0068] The electron transport layer SnO2 was spin-coated on the ITO transparent conductive glass with a thickness of 30 nm;

[0069] The perovskite absorption layer is spin-coated on the electron transport layer SnO2 with a thickness of 400nm;

[0070] The specific preparation steps of the perovskite absorption layer are as follows:

[0071] PbI2 was dissolved in N,N-dimethyl-3-methoxypropionamide to obtain solution A, and methylammonium iodide was dissolved in isopropanol to obtain solution B; the concentration of PbI2 in solution A was 500 mg / mL; the concentration of methylammonium iodide in solution B was 30 mg / mL;

[0072] Solution A was spin-coated on the substrate film and annealed to obtain a PbI2 thin film; the spin-coating speed was 2000 r / min and the spin-coating time was 30 s; the annealing temperature was 75 ° C and the annealing time was 30 min;

[0073] Solution B was spin-coated on the PbI2 film and annealed to obtain a perovskite absorption layer (thickness 400 nm); the spin-coating speed was 2000 r / min and the spin-coating time was 30 s; the annealing temperature was 80 ° C and the annealing time was 30 min;

[0074] A hole transport layer spiro-OMeTAD with a thickness of 100 nm was prepared by spin coating on the perovskite absorption layer; and an Au back electrode layer with a thickness of 100 nm was prepared by vapor deposition on the hole transport layer to obtain a perovskite solar cell.

[0075] Example 4

[0076] This embodiment provides a perovskite solar cell. Compared with the embodiment 1, the difference between the perovskite solar cell and the embodiment 1 is that the specific preparation steps of the perovskite absorption layer are as follows:

[0077] PbI2 was dissolved in N,N-dimethyl-3-methoxypropionamide and N,N-dimethylformamide to obtain solution A, wherein the weight ratio of N,N-dimethyl-3-methoxypropionamide to N,N-dimethylformamide was 1:9;

[0078] Methylammonium iodide was dissolved in isopropanol to obtain solution B; the concentration of PbI2 in solution A was 400 mg / mL; the concentration of methylammonium iodide in solution B was 40 mg / mL;

[0079] Solution A was spin-coated on the electron transport layer SnO2 and annealed to obtain a PbI2 thin film; the spin-coating speed was 3000 r / min and the spin-coating time was 20 s; the annealing temperature was 70 ° C and the annealing time was 30 min;

[0080] Solution B was spin-coated on the PbI2 film and annealed to obtain a perovskite absorption layer (thickness 350 nm); the spin-coating speed was 3000 r / min and the spin-coating time was 20 s; the annealing temperature was 90° C. and the annealing time was 30 min.

[0081] Example 5

[0082] This embodiment provides a perovskite solar cell. Compared with the embodiment 1, the difference between the perovskite solar cell and the embodiment 1 is that the specific preparation steps of the perovskite absorption layer are as follows:

[0083] PbI2 was dissolved in N,N-dimethyl-3-methoxypropionamide and N,N-dimethylformamide to obtain solution A, wherein the weight ratio of N,N-dimethyl-3-methoxypropionamide to N,N-dimethylformamide was 5:5;

[0084] Methylammonium iodide was dissolved in isopropanol to obtain solution B; the concentration of PbI2 in solution A was 400 mg / mL; the concentration of methylammonium iodide in solution B was 40 mg / mL;

[0085] Solution A was spin-coated on the electron transport layer SnO2 and annealed to obtain a PbI2 thin film; the spin-coating speed was 3000 r / min and the spin-coating time was 20 s; the annealing temperature was 70 ° C and the annealing time was 30 min;

[0086] Solution B was spin-coated on the PbI2 film and annealed to obtain a perovskite absorption layer (thickness 350 nm); the spin-coating speed was 3000 r / min and the spin-coating time was 20 s; the annealing temperature was 90° C. and the annealing time was 30 min.

[0087] Example 6

[0088] This embodiment provides a perovskite solar cell. Compared with the embodiment 1, the difference between the perovskite solar cell and the embodiment 1 is that the specific preparation steps of the perovskite absorption layer are as follows:

[0089] PbI2 was dissolved in N,N-dimethyl-3-methoxypropionamide, dimethyl sulfoxide, and N,N-dimethylformamide to obtain solution A, wherein the weight ratio of N,N-dimethyl-3-methoxypropionamide, dimethyl sulfoxide, and N,N-dimethylformamide was 2:2:6;

[0090] Methylammonium iodide was dissolved in isopropanol to obtain solution B; the concentration of PbI2 in solution A was 400 mg / mL; the concentration of methylammonium iodide in solution B was 40 mg / mL;

[0091] Solution A was spin-coated on the electron transport layer SnO2 and annealed to obtain a PbI2 thin film; the spin-coating speed was 3000 r / min and the spin-coating time was 20 s; the annealing temperature was 70 ° C and the annealing time was 30 min;

[0092] Solution B was spin-coated on the PbI2 film and annealed to obtain a perovskite absorption layer (thickness 350 nm); the spin-coating speed was 3000 r / min and the spin-coating time was 20 s; the annealing temperature was 90° C. and the annealing time was 30 min.

[0093] Comparative Example 1

[0094] Comparative Example 1 provides a perovskite solar cell, which includes a transparent conductive layer, an electron transport layer, a perovskite absorption layer, a hole transport layer and a back electrode layer; a method for preparing the perovskite solar cell includes the following steps:

[0095] Clean the ITO transparent conductive glass and perform UV-ozone treatment to a thickness of 30 nm;

[0096] The electron transport layer SnO2 was spin-coated on the ITO transparent conductive glass with a thickness of 30 nm;

[0097] The perovskite absorption layer is spin-coated on the electron transport layer SnO2 with a thickness of 350nm;

[0098] The specific preparation steps of the perovskite absorption layer are as follows:

[0099] PbI2 was dissolved in DMF to obtain solution A, and methylammonium iodide was dissolved in isopropanol to obtain solution B; the concentration of PbI2 in solution A was 400 mg / mL; the concentration of methylammonium iodide in solution B was 40 mg / mL;

[0100] Solution A was spin-coated on the electron transport layer SnO2 and annealed to obtain a PbI2 thin film; the spin-coating speed was 3000 r / min and the spin-coating time was 20 s; the annealing temperature was 70 ° C and the annealing time was 30 min;

[0101] Solution B was spin-coated on the PbI2 film and annealed to obtain a perovskite absorption layer (thickness 350 nm); the spin-coating speed was 3000 r / min and the spin-coating time was 20 s; the annealing temperature was 90 ° C and the annealing time was 30 min;

[0102] The hole transport layer spiro-OMeTAD was prepared by spin coating on the perovskite absorber layer with a thickness of 100 nm.

[0103] An Au back electrode layer with a thickness of 100 nm was prepared by vapor deposition on the hole transport layer to obtain a perovskite solar cell.

[0104] Example 7

[0105] The performance of the perovskite solar cells prepared in Examples 1-6 and Comparative Example 1 was tested.

[0106] The performance tests specifically include open circuit voltage Voc, short circuit current density Jsc, fill factor FF, and power conversion efficiency PCE.

[0107] Open circuit voltage Voc refers to the voltage output across the solar cell device when the external circuit of the solar cell device is in an open circuit state under sunlight.

[0108] The short-circuit current density Jsc refers to the current output by a solar cell device per unit area when the external circuit of the solar cell device is in a short-circuit state under sunlight.

[0109] Fill factor FF refers to the ratio of the maximum output power density of a solar cell device to Jsc.Voc, and the formula is:

[0110] FF=Pmax / (Isc.Voc)=(Jmax.Vmax) / (Jsc.Voc);

[0111] Pmax is the maximum output power value of the solar cell device;

[0112] Jmax and Vmax are the maximum current density and maximum operating voltage values ​​of the solar cell device when the solar cell device is in the maximum output power state.

[0113] FF represents the performance of the battery in providing output power;

[0114] The energy conversion efficiency PCE is the ratio of the maximum output power density of the solar cell device to the incident light intensity power density. The formula is:

[0115] PCE=Pmax / Ps=(Jsc.Voc.FF) / Ps;

[0116] Ps represents the power density value of the incident light intensity;

[0117] PCE represents its ability to convert incident light into electrical energy.

[0118] The specific results can be found in Table 1 below.

[0119] Table 1

[0120] Voc / V Jsc / milliampere / square centimeter FF / % PCE / % Example 1 1.05 20.15 64.26 11.87 Example 2 1.03 19.87 68.44 12.05 Example 3 1.08 20.09 63.73 11.93 Example 4 1.04 19.75 60.01 10.59 Example 5 1.05 19.84 62.05 11.21 Example 6 1.04 20.01 61.12 11.05 Comparative Example 1 1.04 19.72 59.18 10.27

[0121] According to the test data in Table 1, the solar cells prepared in Examples 1-5 dissolve PbX2 by using a solvent containing N,N-dimethyl-3-methoxypropionamide. N,N-dimethyl-3-methoxypropionamide has a higher dipole moment, a polarity greater than DMF, and it is easier to dissolve metal salts than DMF. In addition, the precursor solution prepared with N,N-dimethyl-3-methoxypropionamide as a solvent is stable, has a moderate viscosity, can be retained in the atmosphere for a long time, and can better disperse PbX2. After PbX2 is annealed, the uniform surface is more easily combined with methylammonium iodide to obtain a uniform film-forming perovskite absorption layer. The uniform film-forming perovskite absorption layer is applied to a perovskite solar cell, and its filling factor FF and energy conversion efficiency PCE are significantly improved compared with the perovskite absorption layer prepared using DMF (Comparative Example 1) as a solvent.

Claims

1. A precursor solution, characterized in that The precursor solution is prepared by dissolving solute PbX2 in a solvent; wherein X is F, Cl, Br or I; The solvent contains at least N,N-dimethyl-3-methoxypropionamide; The content of the N,N-dimethyl-3-methoxypropionamide is not less than 10%, based on the total weight of the solvent.

2. The precursor solution according to claim 1, characterized in that In the solvent, the content of the N,N-dimethyl-3-methoxypropionamide is not less than 50%, based on the total weight of the solvent.

3. The precursor solution according to claim 1 or 2, characterized in that The solvent further comprises one or more combinations of amide solvents, dimethyl sulfoxide, and γ-butyrolactone.

4. The precursor solution according to claim 1 or 2, characterized in that The concentration of the solute is 0.3-0.5 g / mL.

5. A perovskite absorption layer, characterized in that: The perovskite absorption layer is prepared by coating a methylammonium iodide solution on a precursor film and then annealing the film; Wherein, the precursor film is prepared by annealing the precursor solution according to any one of claims 1 to 4.

6. The perovskite absorption layer according to claim 5, characterized in that The methylammonium iodide solution is prepared by dissolving methylammonium iodide in isopropyl alcohol.

7. The perovskite absorption layer according to claim 5 or 6, characterized in that The concentration of methylammonium iodide in the methylammonium iodide solution is 0.03-0.05 g / mL.

8. The perovskite absorption layer according to claim 5, characterized in that The thickness of the perovskite absorption layer is 350-500 nm.

9. A perovskite solar cell, characterized in that: The perovskite solar cell comprises the perovskite absorption layer according to any one of claims 5 to 8.