Perovskite solar cell and preparation method thereof

Abstract

The invention relates to a perovskite solar cell and a preparation method thereof, the perovskite solar cell comprises a perovskite light absorption layer, and the preparation material of the perovskite light absorption layer comprises zinc chloride and thiourea. A zinc chloride solution and a thiourea solution are respectively added into a perovskite precursor solution for preparing the perovskite light absorption layer, the molar ratio of zinc chloride to thiourea is 1: 3, and the concentration of zinc chloride is 0.01 mM to 0.1 mM. When the perovskite crystal grows, the composite passivator is generated through in-situ reaction, defect sites on the surface of the perovskite crystal are passivated, and the photoelectric property and the long-term stability of the perovskite solar cell are improved.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell fabrication technology, and specifically relates to a perovskite solar cell and its fabrication method. Background Technology

[0002] As an emerging photovoltaic technology, organic-inorganic hybrid perovskite solar cells have developed rapidly, with the photoelectric conversion efficiency of small-area laboratory devices exceeding 25%. Currently, high-efficiency perovskite solar cells typically employ a solution-based rapid crystallization process to prepare the perovskite absorbing layer. This results in a large number of defects in the perovskite absorbing layer film, with the defect concentration at the crystal surface and grain boundaries being much higher than that in the bulk material. These defects exhibit high reactivity and readily undergo chemical reactions under conditions such as water, oxygen, and light, inducing degradation of the perovskite material from the outside in. To improve the performance of perovskite solar cells, it is usually necessary to passivate the defect sites in the perovskite material to reduce the concentration of active defects and suppress their reactivity. Generally, iodine atoms bonded to organic functional groups in perovskite materials have the worst stability, easily breaking their chemical bonds to become free iodide ions, leaving anionic vacancies and insufficiently coordinated cations. These defects significantly impair the performance of perovskite materials. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide a perovskite solar cell and its preparation method, and to propose a novel perovskite defect passivation method, which involves adding zinc chloride and thiourea as raw materials to a perovskite precursor solution, and generating a passivation material in situ at the interface of the perovskite crystal, thereby improving the photoelectric conversion efficiency and stability of the perovskite solar cell.

[0004] The present invention is implemented by providing a perovskite solar cell, comprising a perovskite light-absorbing layer, wherein the material used to prepare the perovskite light-absorbing layer contains zinc chloride and thiourea.

[0005] Typically, introducing trace amounts of exogenous chemical reagents to passivate defects in perovskite crystals can effectively suppress the activity of defect sites and reduce defect concentration. Studies have found that chlorine can effectively passivate iodine vacancies and bind to insufficiently coordinated cations, restoring the chemical environment of defect sites to electroneutrality. Adding zinc chloride to the perovskite light-absorbing layer material to increase the chloride ion concentration achieves this objective.

[0006] Furthermore, the perovskite light-absorbing layer is prepared using a perovskite precursor solution, which contains a zinc chloride solution and a thiourea solution.

[0007] Furthermore, the molar ratio of zinc chloride to thiourea is 1:3.

[0008] Furthermore, the concentration of zinc chloride is 0.01 mM to 0.1 mM.

[0009] The present invention is implemented as follows: a method for preparing a perovskite solar cell as described above is provided, comprising the following steps: adding zinc chloride solution and thiourea solution to the perovskite precursor solution for preparing the perovskite light-absorbing layer, wherein the molar ratio of zinc chloride to thiourea is 1:3, and the concentration of zinc chloride is 0.01 mM to 0.1 mM.

[0010] Compared with existing technologies, the perovskite solar cell and its fabrication method of the present invention include a perovskite light-absorbing layer, wherein the fabrication material of the perovskite light-absorbing layer contains zinc chloride and thiourea. During the growth of the perovskite crystal, a composite passivating agent is generated in situ to passivate defect sites on the surface of the perovskite crystal, thereby improving the photoelectric performance and long-term stability of the perovskite solar cell. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the performance test curves of the perovskite solar cells prepared in various embodiments of the present invention;

[0012] Figure 2 This is a schematic diagram of the continuous illumination stability test curves of the maximum power point of the perovskite solar cells prepared in various embodiments of the present invention. Detailed Implementation

[0013] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0014] A preferred embodiment of the perovskite solar cell of the present invention includes a perovskite light-absorbing layer, wherein the material used to prepare the perovskite light-absorbing layer contains zinc chloride and thiourea.

[0015] The perovskite light-absorbing layer is prepared using a perovskite precursor solution containing a zinc chloride solution and a thiourea solution. The molar ratio of zinc chloride to thiourea is 1:3. The concentration of zinc chloride is 0.01 mM to 0.1 mM.

[0016] Zinc chloride and thiourea undergo the following chemical reaction upon addition to the perovskite precursor solution:

[0017] CS(NH2)2+ZnCl2→Zn(SCN2H4)2Cl2;

[0018] Zn(SCN2H4)2Cl2→ZnS+NH4ZnCl3+2NH3+HCl+CS2+HNCS+2H2NCN.

[0019] In the formula, CS(NH2)2 is thiourea and ZnCl2 is zinc chloride.

[0020] Therefore, the passivation materials formed on the surface of perovskite crystals mainly consist of Zn(SCN2H4)2Cl2 and ZnS, and the two passivation materials work together to passivate the defect sites of perovskite crystals.

[0021] The present invention also discloses a method for preparing a perovskite solar cell as described above, comprising the following steps: adding zinc chloride solution and thiourea solution to the perovskite precursor solution for preparing the perovskite light-absorbing layer, wherein the molar ratio of zinc chloride to thiourea is 1:3, and the concentration of zinc chloride is 0.01mM to 0.1mM.

[0022] The perovskite solar cell and its preparation method of the present invention are further illustrated below through specific embodiments.

[0023] Example 1

[0024] The first embodiment of the method for fabricating perovskite solar cells of the present invention includes the following steps:

[0025] Step 11. Use cleaning agent, purified water, acetone and isopropanol in sequence to ultrasonically clean the FTO conductive glass, and then treat it with ultraviolet ozone for 15 minutes.

[0026] Step 12. Spin-coat a 2.5 wt% tin dioxide nano-aqueous dispersion onto a clean FTO surface, anneal at 150°C for 30 minutes to deposit an electron transport layer.

[0027] Step 13. Preparation of perovskite Cs 0.05 (FA 0.9 MA 0.1 ) 0.95 Pb(I 0.97 br 0.03 The precursor solution of 3 was prepared by solvent of DMF:DMSO mixture with a volume ratio of 4:1 and a concentration of 1.2 mol / L. Zinc chloride and thiourea were added sequentially with concentrations of 0.02 mM and 0.06 mM, respectively, and stirred to dissolve. The mixed perovskite precursor solution was dropped onto the surface of the electron transport layer and spin-coated at 5000 rpm for 10 s. 200 μL of chlorobenzene was then rapidly added, and spin-coated for another 20 s. The substrate was then removed and annealed at 100 °C for 30 minutes to complete the preparation of the perovskite light-absorbing layer.

[0028] Step 14. Add N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate to a Spiro chlorobenzene solution with a concentration of 70 mg / mL, which accounts for 10% of the Spiro molar ratio; stir thoroughly for 12 h, filter, and spin-coat at 3000 rpm to deposit it onto the surface of the perovskite light-absorbing layer to form a hole transport layer.

[0029] Step 15. Deposit a 60-nanometer-thick layer of gold on the surface of the hole transport layer to complete the fabrication of the perovskite solar cell.

[0030] Example 2

[0031] A second embodiment of the method for preparing perovskite solar cells of the present invention includes the following steps:

[0032] Step 21. Use cleaning agent, purified water, acetone and isopropanol in sequence to ultrasonically clean the ITO conductive glass, and then treat it with ultraviolet ozone for 15 minutes.

[0033] Step 22. Prepare a 2 mg / mL PTAA chlorobenzene solution, drop it onto the ITO surface, spin coat at 4000 rpm for 30 s, and anneal at 100 °C for 10 minutes to prepare a 5 nm thick hole transport layer.

[0034] Step 23. Prepare perovskite FA 0.6 MA 0.4 The PbI3 precursor solution was prepared by adding a DMF:NMP mixture (9:1 volume ratio) at a concentration of 1.5 mol / L to the solvent. Zinc chloride and thiourea were then added sequentially at concentrations of 0.07 mM and 0.21 mM, respectively, and stirred until dissolved. The mixed perovskite precursor solution was then dropped onto the surface of the hole transport layer and spin-coated at 6000 rpm for 10 s. One mL of diethyl ether was then rapidly added, followed by spin-coating and annealing at 100 °C for 10 minutes to complete the preparation of the perovskite light-absorbing layer.

[0035] Step 24. Sequentially deposit 30 nm C60 and 5 nm BCP on the surface of the perovskite light-absorbing layer as an electron transport layer and a blocking layer.

[0036] Step 25. Deposit a 100-nanometer-thick layer of silver on the barrier layer to complete the fabrication of the perovskite solar cell.

[0037] The perovskite solar cells prepared in Examples 1 and 2 were subjected to performance tests, and the results are shown in Table 1 and Table 2. Figure 1 The performance test JV graph and parameters shown are as follows: Figure 2 The illumination stability curve is shown.

[0038] Table 1 Performance test results of perovskite solar cells in Examples 1 and 2

[0039]

[0040]

[0041] from Figure 1 As can be seen from Table 1, the photoelectric conversion efficiency of the perovskite solar cell in Example 1 is 24.29%, and the photoelectric conversion efficiency of the perovskite solar cell in Example 2 is 22.40%, both achieving good photoelectric conversion efficiency results.

[0042] from Figure 2 It can be seen that after 1200 hours of continuous illumination, the perovskite solar cell of Example 1 has a degradation rate of 0.90%, and the perovskite solar cell of Example 2 has a degradation rate of 0.75%. Both Examples 1 and 2 have good light stability.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A perovskite solar cell, comprising a perovskite light-absorbing layer, characterized in that, The materials used to prepare the perovskite light-absorbing layer contain zinc chloride and thiourea.

2. The perovskite solar cell as described in claim 1, characterized in that, The perovskite light-absorbing layer is prepared using a perovskite precursor solution, which contains a zinc chloride solution and a thiourea solution.

3. The perovskite solar cell as described in claim 2, characterized in that, The molar ratio of zinc chloride to thiourea is 1:

3.

4. The perovskite solar cell according to claim 2, characterized in that, The concentration of zinc chloride is 0.01 mM to 0.1 mM.

5. A method for preparing a perovskite solar cell as described in any one of claims 1 to 4, characterized in that, The process includes the following steps: adding zinc chloride solution and thiourea solution to the perovskite precursor solution for preparing the perovskite light-absorbing layer, wherein the molar ratio of zinc chloride to thiourea is 1:3, and the concentration of zinc chloride is 0.01 mM to 0.1 mM.

6. The method for preparing a perovskite solar cell as described in claim 5, characterized in that, Includes the following steps: Step 11. Use cleaning agent, purified water, acetone and isopropanol in sequence to ultrasonically clean the FTO conductive glass, and then treat it with ultraviolet ozone for 15 minutes. Step 12. Spin-coat a 2.5 wt% tin dioxide nano-aqueous dispersion onto a clean FTO surface, anneal at 150°C for 30 minutes to deposit an electron transport layer; Step 13. Preparation of perovskite Cs 0.05 (FA 0.9 MA 0.1 ) 0.95 Pb(I 0.97 br 0.03 The precursor solution of 3 was prepared by using a DMF:DMSO mixture with a volume ratio of 4:1 and a concentration of 1.2 mol / L as the solvent. Zinc chloride and thiourea were then added sequentially at concentrations of 0.02 mM and 0.06 mM, respectively, and stirred until dissolved. The mixed perovskite precursor solution was then dropped onto the surface of the electron transport layer and spin-coated at 5000 rpm for 10 s. 200 μL of chlorobenzene was then rapidly added, followed by spin-coating for another 20 s. The substrate was then removed and annealed at 100 °C for 30 minutes to complete the preparation of the perovskite light-absorbing layer. Step 14. Add N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate to a Spiro chlorobenzene solution with a concentration of 70 mg / mL, which accounts for 10% of the Spiro content; stir thoroughly for 12 h, filter, and spin-coat at 3000 rpm to deposit it onto the surface of the perovskite light-absorbing layer to form a hole transport layer. Step 15. Deposit a 60-nanometer-thick layer of gold on the surface of the hole transport layer to complete the fabrication of the perovskite solar cell.

7. The method for preparing a perovskite solar cell as described in claim 5, characterized in that, Includes the following steps: Step 21. Use cleaning agent, purified water, acetone and isopropanol in sequence to ultrasonically clean the ITO conductive glass, and then treat it with ultraviolet ozone for 15 minutes. Step 22. Prepare a 2 mg / mL PTAA chlorobenzene solution, drop it onto the ITO surface, spin coat at 4000 rpm for 30 s, anneal at 100 °C for 10 min, and prepare a 5 nm thick hole transport layer. Step 23. Prepare perovskite FA 0.6 MA 0.4 The precursor solution of PbI3 was prepared by adding a DMF:NMP mixture (9:1 volume ratio) at a concentration of 1.5 mol / L, followed by the addition of zinc chloride and thiourea at concentrations of 0.07 mM and 0.21 mM, respectively, and stirring until dissolved. The mixed perovskite precursor solution was dropped onto the surface of the hole transport layer, spin-coated at 6000 rpm for 10 s, 1 ml of diethyl ether was quickly added, and then spin-coated and annealed at 100 °C for 10 minutes to complete the preparation of the perovskite light-absorbing layer. Step 24. Sequentially deposit 30 nm of C60 and 5 nm of BCP on the surface of the perovskite light-absorbing layer as an electron transport layer and a blocking layer. Step 25. Deposit a 100-nanometer-thick layer of silver on the barrier layer to complete the fabrication of the perovskite solar cell.

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