Solar cell with adjustable band gap, preparation method and application

Abstract

The invention relates to the technical field of solar cells, in particular to a band-gap-adjustable solar cell, a preparation method and application. The preparation method comprises the following steps: (1) cleaning a conductive glass substrate; (2) depositing a hole transport layer on the conductive glass substrate; (3) adding methyl ammonium lead trihalide into a perovskite precursor solution, and depositing the perovskite precursor solution on the hole transport layer to obtain a perovskite light absorption layer; (4) depositing an electron transport layer on the perovskite light absorption layer; and (5) depositing a top electrode on the electron transport layer. The band gap and color of the solar cell can be adjusted, crystallization of the perovskite thin film can be improved, surface and internal defects of the thin film are reduced, and the application environment is widened.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a solar cell with adjustable bandgap, a preparation method and applications. Background Art

[0002] Perovskite solar cells have attracted considerable research attention due to their photovoltaic properties, including a suitable band gap, high carrier mobility, and excellent light absorption and utilization. As living standards gradually improve, people have higher demands for the aesthetics of photovoltaic cells. By adjusting the band gap and changing the color of perovskite films, their application scenarios can be expanded and better cater to the public's aesthetic taste.

[0003] The band gap of perovskites depends largely on the orbital coupling between lead and halogen elements. Existing technologies typically adjust the band gap by adjusting the ratio of iodine and bromine mixtures, and the band gap increases with increasing Br content. However, when the Br content exceeds 20%, perovskite films typically exhibit strong non-radiative recombination and phase separation under light, which reduces the open-circuit voltage of battery devices and causes rapid performance degradation, hindering the long-term stability of perovskite films for application. Summary of the Invention

[0004] In order to address the defects in the prior art, the present invention provides a solar cell with adjustable band gap, a preparation method and an application. By adding MAPbCl3 components to the perovskite precursor of the perovskite solar cell, the band gap and color of the solar cell can be adjusted. At the same time, the crystallization of the perovskite film can be improved, the surface and internal defects of the film can be reduced, and the application environment can be broadened.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a method for preparing a solar cell with adjustable bandgap, comprising the following steps:

[0007] (1) Clean the conductive glass substrate;

[0008] (2) depositing a hole transport layer on the conductive glass substrate;

[0009] (3) adding methylammonium lead trihalide to the perovskite precursor solution and depositing it on the hole transport layer to obtain a perovskite light absorbing layer;

[0010] (4) depositing an electron transport layer on the perovskite light absorbing layer;

[0011] (5) Depositing a top electrode on the electron transport layer.

[0012] Preferably, the perovskite is Cs 0.15 FA0.85 Pb(I 0.4 Br 0.6 )3.

[0013] Preferably, the perovskite precursor solution is obtained by dissolving cesium iodide, formamidine hydroiodide, lead iodide and lead bromide in a solvent.

[0014] Preferably, the methylammonium lead trihalide is selected from any one of MAPbCl3, MAPbI3, and MAPbBr3.

[0015] Preferably, the molar ratio of the methylammonium lead trihalide to the perovskite precursor is (0.2-1.3):1. In some embodiments of the present invention, the molar ratio of the methylammonium lead trihalide to the perovskite precursor is any one of 0.2:1, 0.5:1, 0.8:1, 1.1:1, 1.3:1, or a value between two of them.

[0016] Preferably, the amount of the methylammonium lead trihalide added is 0.2 to 1.3 mol. In some embodiments of the present invention, the amount of the methylammonium lead trihalide added is any one of 0.2 mol, 0.5 mol, 0.8 mol, 1.1 mol, 1.3 mol, or a value in between.

[0017] Preferably, the deposition method of step (3) is two-step spin coating, and the rotation speed parameters of the two-step spin coating are respectively 1000 rpm for 10s with an acceleration of 1000 rpm / s; and 5000 rpm for 30s with an acceleration of 3000 rpm / s.

[0018] Preferably, the material of the hole transport layer is dimethoxycarbazole.

[0019] Preferably, the material of the electron transport layer is phenyl-C 61 -Methyl butyrate.

[0020] Preferably, the step (4) further comprises depositing a buffer layer on the electron transport layer.

[0021] More preferably, the buffer layer material is BCP.

[0022] In a second aspect, the present invention provides a solar cell with adjustable bandgap prepared by the above preparation method.

[0023] In a third aspect, the present invention provides application of the solar cell in an underwater environment.

[0024] Preferably, the underwater environment is specifically an environment 10 meters underwater.

[0025] Preferably, the conditions in the underwater environment are: temperature 22.5°C, radiation intensity 228W / m 2 .

[0026] The beneficial effects of the present invention are:

[0027] During the preparation of perovskite solar cells, the present invention adds methylammonium lead trihalide to the perovskite precursor, which modifies the band gap and color of the perovskite material, broadening its application range. The addition of methylammonium lead trihalide improves the grain boundaries of the perovskite film, increases the grain size of the perovskite film, broadens the lattice, and increases surface coverage, resulting in a dense, hole-free morphology. The introduction of methylammonium lead trihalide also introduces additional charge carriers (electrons or holes), enhancing the carrier transport capacity of the perovskite device and thus improving the material's electrical conductivity. The overall preparation method is simple and readily available.

[0028] The solar cell prepared by the present invention has better chemical stability and moisture resistance, which prolongs its life in practical applications. The band gap is close to 2.0eV, which is more suitable for full perovskite stacking. The color is more reddish, and the single-junction cell device is more beautiful, making it more suitable for underwater power generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Characterization diagram of the external quantum efficiency of the perovskite cells prepared in each example.

[0030] Figure 2 These are SEM characterization images of the perovskite films prepared in Example 1 and Example 6.

[0031] Figure 3 Graphs showing the cell JV curve and external quantum efficiency curve corresponding to the solar cell device of Example 6.

[0032] Figure 4 This is a performance diagram of the solar cell device prepared in Example 6 tested in a simulated 10-meter underwater environment. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the technical solution of the invention, the present invention is further described in detail below in conjunction with specific implementation methods.

[0034] Example 1

[0035] This embodiment provides an inverted perovskite solar cell, whose structure includes, from bottom to top, conductive glass, a hole transport layer, a perovskite light absorption layer, an electron transport layer, and a top electrode.

[0036] The preparation of the inverse perovskite solar cell comprises the following steps:

[0037] (1) The indium tin oxide (ITO) conductive glass substrate was gently wiped clean with anhydrous ethanol and then treated in a UV light ozone cleaning machine for 20 minutes to remove impurities on the substrate surface and improve the substrate wettability;

[0038] (2) 70 μL of a 0.6 mg / ml dimethoxycarbazole (Me-2PACz) solution (ethanol solvent) was spin-coated on a conductive substrate at a speed of 3000 rpm for 30 s with an acceleration of 3000 rpm / s. To ensure uniformity of the film, the solution was allowed to stand for 5 s before spin coating. The film was then placed on a hot plate at 100°C for 10 min to obtain a hole transport layer.

[0039] (3) Perovskite precursor solution (Cs 0.15 FA 0.85 Pb(I 0.4 Br 0.6 )3) 1M cesium iodide (CsI), formamidine hydroiodide (FAI), lead iodide (PbI2) and lead bromide (PbBr2) were dissolved in DFM:DMSO (volume ratio of 4:1) in a mass ratio of 0.15:0.85:0.1:0.9, stirred for 1 hour to fully dissolve, and then 0mol of methylammonium lead trichloride (MAPbCl3) was added, mixed evenly and then spin-coated on the hole transport layer by a two-step spin coating method. The dosage was 40 μL, and the two-step speed parameters were 1000 rpm for 10 seconds with an acceleration of 1000 rpm / s, and 5000 rpm for 30 seconds with an acceleration of 3000 rpm / s. 200 μL of anisole was added as an antisolvent in the last 8 seconds of the spin coating to promote the crystallization of the perovskite film. Finally, the spin-coated film was placed on a hot plate at 100°C for annealing for 10 minutes to obtain the perovskite light-absorbing layer.

[0040] (4) First, spin-coat phenyl-C with a concentration of 20 mg / ml on the perovskite light-absorbing layer. 61 -Methyl butyrate (PC 61 BM) (solvent: chlorobenzene) 40 μL, spin coating speed at 1500 rpm for 30 s, acceleration at 1500 rpm / s, as an electron transport layer; then spin coating 70 μL of bathocuproine (BCP) (solvent: isopropanol) with a concentration of 0.5 mg / ml, spin coating speed at 6000 rpm for 30 s, acceleration at 6000 rpm / s, as a buffer layer;

[0041] (5) A Ag electrode was deposited onto the BCP buffer layer using thermal evaporation as a top electrode with a thickness of 120 nm.

[0042] Example 2

[0043] Same as Example 1, except that the amount of methylammonium lead trichloride (MAPbCl3) added in step (3) is 0.2 mol.

[0044] Example 3

[0045] Same as Example 1, except that the amount of methylammonium lead trichloride (MAPbCl3) added in step (3) is 0.5 mol.

[0046] Example 4

[0047] Same as Example 1, except that the amount of methylammonium lead trichloride (MAPbCl3) added in step (3) is 0.8 mol.

[0048] Example 5

[0049] Same as Example 1, except that the amount of methylammonium lead trichloride (MAPbCl3) added in step (3) is 1.1 mol.

[0050] Example 6

[0051] Same as Example 1, except that the amount of methylammonium lead trichloride (MAPbCl3) added in step (3) is 1.3 mol.

[0052] Effect Example 1: Solar Cell Bandgap Effect

[0053] The band gaps of the solar cells obtained in Examples 1 to 6 were tested, and the results are shown in Table 1.

[0054] Table 1

[0055] sample <![CDATA[Addition amount of MAPbCl3 (mol)]]> Band gap (eV) Example 1 0 1.9 Example 2 0.2 1.91 Example 3 0.5 1.93 Example 4 0.8 1.95 Example 5 1.1 1.97 Example 6 1.3 1.98

[0056] As can be seen from Table 1, compared with the solar cell without MAPbCl3 (Example 1), the band gap of the solar cell device with MAPbCl3 added in the present invention has been effectively improved, reaching a maximum of 1.98eV. It is worth noting that due to the limited solubility of methylammonium lead trichloride (MAPbCl3) single crystals, when the concentration exceeds 1.3 mol, MAPbCl3 can no longer be completely dissolved, making it difficult to obtain a solar cell with a higher band gap. Due to the tunable band gap advantage of MAPbCl3, the band gap can be widened from 1.9eV to 1.98eV, which is more suitable for triple-junction all-perovskite stacks. If a single-junction cell is prepared for low-light or underwater photovoltaics, it can meet the spectral requirements of different water depths, thereby maximizing the use of light energy.

[0057] The external quantum efficiency (EQE) of the perovskite cells prepared in each example was characterized, and the results are shown in Figure 1It can be seen that with the change of the concentration of MAPbCl3 introduced, the corresponding absorption cutoff edge of the battery also changes significantly. When the concentration is 1.3 mol, the absorption edge is the narrowest and the corresponding band gap is also the widest, reaching 1.98 eV.

[0058] Effect Example 2 Surface morphology of perovskite film

[0059] The perovskite films prepared in Example 1 and Example 6 were characterized by SEM. Figure 2 The left image shows the characterization of Example 1, and the right image shows the characterization of Example 6. It can be seen that the introduction of MAPbCl3 leads to a more uniform and dense perovskite film morphology. Due to the change in band gap, the film grain size also shows a significant trend of change, with increased surface coverage and a dense, void-free film. The inset in the upper right corner shows that as the band gap increases, the color of the perovskite film also changes, from brown-red to a red, translucent cell, which is more aesthetically pleasing.

[0060] Effect Example 3: Electrochemical Performance Test of Solar Cells

[0061] Figure 3 The JV curve (left) and external quantum efficiency (EQE) curve (right) of the solar cell device of Example 6 are shown in FIG. OC The FF is as high as 84.06%, and the final photoelectric conversion efficiency is 15.06%, which is one of the highest efficiencies at 1.98eV. Figure 3 (Right) shows the EQE curve corresponding to this band gap. It can be seen that this band gap material has a good photoelectric conversion ability in the range of 400-600nm, and the curve intensity is higher. Subsequently, the short-circuit current density (J SC ) is 12.76 mA / cm 2 This is consistent with the J SC The results are basically consistent, thus verifying the reliability of the device current.

[0062] Effect Example 4: Application Performance in Underwater Environment

[0063] The 1.98 eV single-junction cell device prepared in Example 6 was placed in a simulated underwater environment at 10 meters for performance testing. The simulated underwater illumination experiment was carried out in a nitrogen-filled glove box at a temperature of 22.5°C. The test light source was a xenon lamp, and the radiometer showed an intensity of 228 W / m 2 , the results are shown in Figure 4 . Figure 4 It shows that the fill factor (FF) can reach 81.05%, and the final photoelectric conversion efficiency (PCE) is 6.51%, which is converted to an efficiency of 28.55% at 10 meters underwater, which also confirms the prospect of using this bandgap battery device in underwater photovoltaics.

[0064] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. Persons skilled in the art will appreciate that improvements and modifications may be made without departing from the spirit and scope of the present invention, and such improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a solar cell with adjustable bandgap, characterized in that: The following steps are involved: (1) Clean the conductive glass substrate; (2) depositing a hole transport layer on the conductive glass substrate; (3) adding methylammonium lead trihalide to the perovskite precursor solution and depositing it on the hole transport layer to obtain a perovskite light absorbing layer; (4) depositing an electron transport layer on the perovskite light absorbing layer; (5) Depositing a top electrode on the electron transport layer.

2. The preparation method according to claim 1, characterized in that: The methylammonium lead trihalide is selected from any one of MAPbCl3, MAPbI3, and MAPbBr3.

3. The preparation method according to claim 1, characterized in that: The perovskite precursor solution is obtained by dissolving cesium iodide, formamidine hydroiodide, lead iodide and lead bromide in a solvent.

4. The preparation method according to claim 1, characterized in that: The deposition method of step (3) is two-step spin coating, and the rotation speed parameters of the two-step spin coating are respectively 1000 rpm for 10 seconds with an acceleration of 1000 rpm / s; and 5000 rpm for 30 seconds with an acceleration of 3000 rpm / s.

5. The preparation method according to claim 1, characterized in that: The step (4) also includes depositing a buffer layer on the electron transport layer.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The molar ratio of the methylammonium lead trihalide to the perovskite precursor is (0.2-1.3):

1.

7. A solar cell with adjustable bandgap prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the solar cell according to claim 7 in an underwater environment.

9. The use according to claim 8, characterized in that: The underwater environment is specifically an environment 10 meters underwater.

10. The use according to claim 9, characterized in that: The conditions in the underwater environment are: temperature 22.5°C, radiation intensity 228W / m 2 .

Images