An axisymmetric small-molecule assisted crystallization inorganic perovskite solar cell and a preparation method thereof

Abstract

The application discloses an axisymmetric type small-molecule assisted crystallization inorganic perovskite solar cell and a preparation method thereof. By introducing 2,6-pyridine dicarboxamide as a modulation molecule in a perovskite precursor solution, a perovskite absorption layer is obtained by using a one-step spin coating method in a nitrogen environment and annealing in an air environment. The amide and pyridine groups in the structure of 2,6-pyridine dicarboxamide form interaction forces with different lead in the inorganic perovskite, induce perovskite crystal face orientation, increase the grain size, reduce the grain boundary, and at the same time, play the role of in-situ passivation and improve the crystalline quality, reduce the non-radiative recombination of carriers caused by trap states. In addition, the uniform stress between them effectively inhibits the transformation of the perovskite phase from the optically active alpha phase to the non-perovskite delta phase under high humidity, and finally to a certain extent, the problems of poor crystalline quality, high defect state density, serious open circuit voltage loss and phase instability in the inorganic perovskite solar cell are relieved.

Description

Technical Field

[0001] The present invention belongs to the field of new energy, and specifically relates to an axially symmetric small molecule-assisted crystallization inorganic perovskite solar cell and a preparation method thereof. Background Art

[0002] In recent years, in order to solve the global energy crisis, environmental pollution and other problems and seek sustainable development of human society, people are seeking and developing new clean and renewable energy. Among them, wide-bandgap perovskite solar cells have received widespread attention in the fields of semi-transparent devices, tandem cells and indoor photovoltaics, and have broad application prospects in terawatt-level deployment. Inorganic perovskite solar cells (IPSCs) have become ideal candidates for top cells in perovskite / crystalline silicon tandem solar cells due to their suitable bandgap and excellent photothermal stability. However, despite extensive research, polycrystalline inorganic perovskite films prepared by the solution method still face problems such as poor crystallization quality and high defect state density, which can cause serious non-radiative recombination of carriers, resulting in large open-circuit voltage loss (V OC ), resulting in a large gap in photoelectric conversion efficiency (PCE) compared with organic-inorganic hybrid perovskite solar cells, which seriously limits their commercial application and development.

[0003] Another key factor limiting the commercialization of IPSCs is the instability of the inorganic perovskite phase. The small radius of Cs ions in the inorganic perovskite crystal structure results in a relatively small tolerance factor. The black phases (α, β, and γ phases) are severely unstable under ambient conditions. In particular, when exposed to high relative humidity, the black phase rapidly transforms into an optically inactive yellow phase (δ phase), causing severe collapse of the perovskite structure. This further exacerbates the phase transition and instability of the inorganic perovskite film, significantly limiting the device performance and industrialization of IPSCs.

[0004] In summary, the problems of existing inorganic perovskite solar cells are mainly poor crystal quality, high defect state density, severe open circuit voltage loss and phase instability. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned deficiencies in the prior art and to provide an axially symmetric small molecule-assisted crystallization inorganic perovskite solar cell and a preparation method thereof.

[0006] To achieve the objectives of this invention, we propose introducing the axisymmetric small molecule 2,6-pyridinedicarboxamide into a perovskite precursor solution. During the annealing process, we manipulate the perovskite crystal orientation and extend the annealing time of inorganic perovskite films in air. The amide and pyridine groups in the molecular structure interact with the lead in the inorganic perovskite. This modulation modulates the perovskite crystal plane orientation, increases grain size, improves perovskite crystallinity, and enhances film quality. This effectively passivates perovskite defects, reduces nonradiative recombination, promotes efficient carrier transport, and achieves higher open-circuit voltage. Furthermore, the uniform force between the two helps stabilize the perovskite lattice, effectively suppressing phase instabilities and enabling the realization of highly efficient and stable inorganic perovskite solar cells.

[0007] The technical solution of the present invention:

[0008] A method for preparing an axisymmetric small molecule-assisted crystallization inorganic perovskite solar cell, the method comprising:

[0009] (1) cleaning a transparent conductive substrate and preparing an electron transport layer on the transparent conductive substrate;

[0010] (2) spin-coating a perovskite precursor solution containing an axisymmetric small molecule on the electron transport layer, and preparing a perovskite absorption layer after annealing;

[0011] (3) spin coating a hole transport layer precursor solution on the perovskite absorption layer to prepare a hole transport layer;

[0012] (4) preparing a metal / carbon electrode on the hole transport layer;

[0013] The perovskite absorber layer contains 2,6-pyridinedicarboxamide molecules.

[0014] The transparent conductive substrate in step (1) is ITO / FTO conductive glass;

[0015] The electron transport layer in step (1) is TiO2, SnO2 or ZnO and related composites;

[0016] The concentration of the axisymmetric small molecule in the perovskite precursor solution in step (2) is 0.5-15 mg / mL;

[0017] The perovskite precursor solution solvent in step (2) is a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide, and the solute is CsPbI x Br 3-x (0≤X≤3); the concentration of the solute is 0.2-1.5 mol / L; the band gap is 1.68-2.3 eV;

[0018] The perovskite absorption layer described in step (2) is prepared by spin coating a perovskite precursor solution and then annealing, the spin coating speed is 500-5000 rpm / min, preferably the spin coating speed is 1000-3000 rpm / min, and the time is 20-120s; the annealing conditions are annealing at 30-120°C in a nitrogen environment for 0.5-30min, and annealing at 150-350°C in ambient air for 1-30min;

[0019] The hole transport layer in step (3) is Spiro-OMeTAD, Spiro-TTB, PTAA, CuSCN or P3HT, and the spin coating speed is 1000-6000 rpm / min for 10-60 s.

[0020] The metal electrode described in step (4) is a gold or silver electrode deposited with a thickness of 30-200 nm by vacuum evaporation or a carbon electrode obtained by scraping.

[0021] Advantages and positive effects of the present invention:

[0022] The present invention introduces the axisymmetric small molecule 2,6-pyridinedicarboxamide into a perovskite precursor solution and prepares a perovskite thin film via spin coating. During the annealing process, the 2,6-pyridinedicarboxamide molecules, with their symmetrical p-π conjugation and planar configuration, can regulate the perovskite crystal orientation. The amide and pyridine groups interact with the different lead groups in the inorganic perovskite. Through this interaction between the molecule and the perovskite, the perovskite crystal plane orientation is induced, grain size is increased, grain boundaries are reduced, and the crystalline quality of the perovskite film is improved. Furthermore, the 2,6-pyridinedicarboxamide can in situ passivate uncoordinated lead ions in the perovskite, reducing non-radiative carrier recombination caused by trap states, extending carrier lifetime, and minimizing open-circuit voltage loss. Furthermore, the uniform force between the two helps stabilize the perovskite lattice, effectively inhibiting the perovskite phase transition from the optically active α phase to the non-perovskite δ phase at high humidity, thereby improving phase stability. Therefore, the present invention is beneficial for improving the performance of inorganic perovskite solar cells, with simple operation and good reproducibility. Furthermore, the application of 2,6-pyridinedicarboxamide as a perovskite precursor additive in formal inorganic perovskite and crystalline silicon two-terminal tandem solar cells provides a basis for further industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the structure of an inorganic perovskite solar cell according to a specific embodiment of the present invention;

[0024] Figure 2 This is a graph showing the volt-ampere characteristic of an inorganic perovskite solar cell using 2.0 mg / mL of 2,6-pyridinedicarboxamide at a concentration of 0.8 mol / L as a perovskite precursor additive according to a specific embodiment of the present invention;

[0025] Figure 3 This is a graph showing the volt-ampere characteristic of an inorganic perovskite solar cell using 4.0 mg / mL of 2,6-pyridinedicarboxamide at a concentration of 0.8 mol / L as a perovskite precursor additive according to a specific embodiment of the present invention;

[0026] Figure 4 This is a graph showing the volt-ampere characteristic of an inorganic perovskite solar cell using 6.0 mg / mL of 2,6-pyridinedicarboxamide at a concentration of 0.8 mol / L as a perovskite precursor additive according to a specific embodiment of the present invention;

[0027] Figure 5 This is a graph showing the volt-ampere characteristic of an inorganic perovskite solar cell using 2.0 mg / mL of 2,6-pyridinedicarboxamide at a concentration of 0.8 mol / L as a perovskite precursor additive according to a specific embodiment of the present invention;

[0028] Figure 6 This is a graph showing the volt-ampere characteristic of an inorganic perovskite solar cell using 2.0 mg / mL of 2,6-pyridinedicarboxamide at a concentration of 0.6 mol / L as a perovskite precursor additive according to a specific embodiment of the present invention;

[0029] Figure 7 This is a graph showing the volt-ampere characteristic of an inorganic perovskite solar cell using 2.0 mg / mL of 2,6-pyridinedicarboxamide at a concentration of 0.8 mol / L as a perovskite precursor additive according to a specific embodiment of the present invention;

[0030] Figure 8 is a graph showing the volt-ampere characteristic of an inorganic perovskite solar cell without 2,6-pyridinedicarboxamide as a perovskite precursor additive at a concentration of 0.8 mol / L according to a comparative embodiment of the present invention;

[0031] Figure 9 This is a schematic diagram of the mode of action of the axisymmetric small molecule 2,6-pyridinedicarboxamide introduced in the present invention. DETAILED DESCRIPTION

[0032] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] The present invention provides an axially symmetrical small molecule assisted crystallization inorganic perovskite solar cell and its preparation method; 2,6-pyridinedicarboxamide is used as an additive to modify and optimize the perovskite precursor solution, thereby achieving perovskite crystal plane orientation control and increasing grain size, playing the role of in-situ passivation and improving crystallization quality, and effectively improving the efficiency and stability of the perovskite solar cell. The cell structure is as shown in the attached figure. Figure 1As shown, stacked from bottom to top are a transparent conductive substrate, an electron transport layer, a perovskite absorption layer, a hole transport layer and a metal / carbon electrode.

[0034] Example 1:

[0035] The present invention provides an axisymmetric molecule-assisted crystallization inorganic perovskite solar cell and a preparation method thereof, comprising the following steps:

[0036] 1. Place the ITO / FTO conductive glass substrate (2×2cm 2 ) ultrasonically clean the substrate with detergent, deionized water, and isopropyl alcohol for 15 min, blow dry the moisture with nitrogen, and treat the substrate with UV-ozone for 20 min to obtain a clean and well-wettable ITO / FTO conductive glass substrate;

[0037] 2. Mix deionized water and SnO2 colloid in a volume ratio of 3:1 to obtain a SnO2 colloid solution (only SnO2 is used as an example here);

[0038] 3. Spin-coat the SnO2 colloidal solution prepared in step 2 onto the ITO / FTO conductive glass substrate prepared in step 1 at a speed of 1000-6000 rpm / min for 10-60 s; then anneal in ambient air at 100-200°C for 5-60 min to obtain an electron transport layer.

[0039] 4. Dissolve CsI, HPbI3, PbBr2, and CsBr in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide at a certain molar ratio, and add 2.0 mg / mL of 2,6-pyridinedicarboxamide as an additive. Then, heat and stir at 60°C in a nitrogen environment until completely dissolved, to obtain a CsPbI solution containing 2.0 mg / mL of 2,6-pyridinedicarboxamide at a concentration of 0.8 mol / L. x Br 3-x Perovskite precursor solution;

[0040] 5. Spin-coat the perovskite solution obtained in step 4 on the electron transport layer obtained in step 3 at a rotation speed of 500-9000 rpm / min for 10-120 s; then anneal in a nitrogen environment at 30-120° C. for 0.5-30 min, and then anneal in ambient air at 150-350° C. for 1-30 min to obtain a perovskite absorption layer;

[0041] 6. Add 72.3 mg of Spiro-OMeTAD, 35 μL of LiTFSI solution (260 mg of LiTFSI powder dissolved in 1 mL of acetonitrile), and 30 μL of 4-tert-butylpyridine to 1 mL of chlorobenzene and stir until completely dissolved to obtain a hole transport layer precursor solution (Here, only Spiro-OMeTAD is used as an example);

[0042] 7. Spin-coat the hole transport layer precursor solution obtained in step 6 on the perovskite absorption layer prepared in step 5 using a one-step spin coating method at a spin coating speed of 1000-6000 rpm / min for 5-60 s to prepare a hole transport layer;

[0043] 8. Evaporate a 30-200 nm gold / silver electrode or scrape a carbon electrode on the hole transport layer of step 7 to prepare an inorganic perovskite solar cell.

[0044] Experimental results: Conduct performance tests on solar cells, such as Figure 2 As shown, at AM1.5, 100mW / cm 2 Under standard light intensity, the open circuit voltage of the solar cell prepared in this embodiment is 1.311V and the short circuit current density is 20.39mA / cm 2 , filling factor 80.22% and efficiency 21.44%.

[0045] Example 2:

[0046] The present invention provides an axially symmetric small molecule-assisted crystallization inorganic perovskite solar cell and a preparation method thereof, comprising the following steps:

[0047] 1. Place the ITO / FTO conductive glass substrate (2×2cm 2 ) ultrasonically clean the substrate with detergent, deionized water, and isopropyl alcohol for 15 min, blow dry the moisture with nitrogen, and treat the substrate with UV-ozone for 20 min to obtain a clean and well-wettable ITO / FTO conductive glass substrate;

[0048] 2. Mix deionized water and SnO2 colloid in a volume ratio of 3:1 to obtain a SnO2 colloid solution (only SnO2 is used as an example here);

[0049] 3. Spin-coat the SnO2 colloidal solution prepared in step 2 onto the ITO / FTO conductive glass substrate prepared in step 1 at a speed of 1000-6000 rpm / min for 10-120 s; then anneal in ambient air at 100-200°C for 5-60 min to obtain an electron transport layer.

[0050] 4. Dissolve CsI, HPbI3, PbBr2, and CsBr in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide at a certain molar ratio, and add 4.0 mg / mL of 2,6-pyridinedicarboxamide as an additive. Then, heat and stir at 60°C in a nitrogen environment until completely dissolved, to obtain a CsPbI solution containing 4.0 mg / mL of 2,6-pyridinedicarboxamide at a concentration of 0.8 mol / L. x Br 3-xPerovskite precursor solution;

[0051] 5. Spin-coat the perovskite solution obtained in step 4 on the electron transport layer obtained in step 3 at a speed of 500-9000 rpm / min for 10-120 s; then anneal in a nitrogen environment at 30-120° C. for 0.5-30 min, and anneal in ambient air at 150-350° C. for 1-30 min to obtain a perovskite absorption layer;

[0052] 6. Add 72.3 mg of Spiro-OMeTAD, 35 μL of LiTFSI solution (260 mg of LiTFSI powder dissolved in 1 mL of acetonitrile), and 30 μL of 4-tert-butylpyridine to 1 mL of chlorobenzene and stir until completely dissolved to obtain a hole transport layer precursor solution (Here, only Spiro-OMeTAD is used as an example);

[0053] 7. Spin-coat the hole transport layer precursor solution obtained in step 6 on the perovskite absorption layer prepared in step 5 using a one-step spin coating method at a spin coating speed of 1000-6000 rpm / min for 5-60 s to prepare a hole transport layer;

[0054] 8. Evaporate a 30-200 nm gold / silver electrode or scrape a carbon electrode on the hole transport layer of step 7 to prepare an inorganic perovskite solar cell.

[0055] Experimental results: Conduct performance tests on solar cells, such as Figure 3 As shown, at AM1.5, 100mW / cm 2 Under standard light intensity, the open circuit voltage of the solar cell prepared in this embodiment is 1.342V and the short circuit current density is 20.40mA / cm 2 , fill factor 80.59% and efficiency 22.07%.

[0056] Example 3:

[0057] The present invention provides an axially symmetric small molecule-assisted crystallization inorganic perovskite solar cell and a preparation method thereof, comprising the following steps:

[0058] 1. Place the ITO / FTO conductive glass substrate (2×2cm 2 ) ultrasonically clean the substrate with detergent, deionized water, and isopropyl alcohol for 15 min, blow dry the moisture with nitrogen, and treat the substrate with UV-ozone for 20 min to obtain a clean and well-wettable ITO / FTO conductive glass substrate;

[0059] 2. Mix deionized water and SnO2 colloid in a volume ratio of 3:1 to obtain a SnO2 colloid solution (only SnO2 is used as an example here);

[0060] 3. Spin-coat the SnO2 colloidal solution prepared in step 2 onto the ITO / FTO conductive glass substrate prepared in step 1 at a speed of 3000 rpm / min for 30 seconds; then anneal at 180°C in ambient air for 30 minutes to obtain an electron transport layer.

[0061] 4. Dissolve CsI, HPbI3, PbBr2, and CsBr in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide at a certain molar ratio, and add 6.0 mg / mL of 2,6-pyridinedicarboxamide as an additive. Then, heat and stir at 60°C in a nitrogen environment until completely dissolved, to obtain a CsPbI solution containing 6.0 mg / mL of 2,6-pyridinedicarboxamide at a concentration of 0.8 mol / L. x Br 3-x Perovskite precursor solution;

[0062] 5. Spin-coat the perovskite solution obtained in step 4 on the electron transport layer obtained in step 3 at a speed of 500-9000 rpm / min for 10-120 s; then anneal in a nitrogen environment at 30-120° C. for 0.5-30 min, and anneal in ambient air at 150-350° C. for 1-30 min to obtain a perovskite absorption layer;

[0063] 6. Add 72.3 mg of Spiro-OMeTAD, 35 μL of LiTFSI solution (260 mg of LiTFSI powder dissolved in 1 mL of acetonitrile), and 30 μL of 4-tert-butylpyridine to 1 mL of chlorobenzene and stir until completely dissolved to obtain a hole transport layer precursor solution (Here, only Spiro-OMeTAD is used as an example);

[0064] 7. Spin-coat the hole transport layer precursor solution obtained in step 6 on the perovskite absorption layer prepared in step 5 using a one-step spin coating method at a spin coating speed of 1000-6000 rpm / min for 5-60 s to prepare a hole transport layer;

[0065] 8. Evaporate a 30-200 nm gold / silver electrode or scrape a carbon electrode on the hole transport layer of step 7 to prepare an inorganic perovskite solar cell.

[0066] Experimental results: Conduct performance tests on solar cells, such as Figure 4 As shown, at AM1.5, 100mW / cm 2 Under standard light intensity, the open circuit voltage of the solar cell prepared in this embodiment is 1.320V and the short circuit current density is 20.26mA / cm 2 , filling factor 76.73% and efficiency 20.53%.

[0067] Example 4:

[0068] The present invention provides an axially symmetric small molecule-assisted crystallization inorganic perovskite solar cell and a preparation method thereof, comprising the following steps:

[0069] 1. Place the ITO / FTO conductive glass substrate (2×2cm 2 ) ultrasonically clean the substrate with detergent, deionized water, and isopropyl alcohol for 15 min, blow dry the moisture with nitrogen, and treat the substrate with UV-ozone for 20 min to obtain a clean and well-wettable ITO / FTO conductive glass substrate;

[0070] 2. Mix deionized water and SnO2 colloid in a volume ratio of 3:1 to obtain a SnO2 colloid solution (only SnO2 is used as an example here);

[0071] 3. Spin-coat the SnO2 colloidal solution prepared in step 2 onto the ITO / FTO conductive glass substrate prepared in step 1 at a speed of 3000 rpm / min for 30 seconds; then anneal at 180°C in ambient air for 30 minutes to obtain an electron transport layer.

[0072] 4. Dissolve CsI, HPbI3, PbBr2, and CsBr in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide at a certain molar ratio, and add 2.0 mg / mL of 2,6-pyridinedicarboxamide as an additive. Then, heat and stir at 60°C in a nitrogen environment until completely dissolved, to obtain a CsPbI solution containing 2.0 mg / mL of 2,6-pyridinedicarboxamide at a concentration of 0.8 mol / L. x Br 3-x Perovskite precursor solution;

[0073] 5. Spin-coat the perovskite solution obtained in step 4 on the electron transport layer obtained in step 3 at a speed of 500-9000 rpm / min for 10-120 s; then anneal in a nitrogen environment at 30-120° C. for 0.5-30 min, and anneal in ambient air at 150-350° C. for 1-30 min to obtain a perovskite absorption layer;

[0074] 6. Add 72.3 mg of Spiro-OMeTAD, 35 μL of LiTFSI solution (260 mg of LiTFSI powder dissolved in 1 mL of acetonitrile), and 30 μL of 4-tert-butylpyridine to 1 mL of chlorobenzene and stir until completely dissolved to obtain a hole transport layer precursor solution (Here, only Spiro-OMeTAD is used as an example);

[0075] 7. Spin-coat the hole transport layer precursor solution obtained in step 6 on the perovskite absorption layer prepared in step 5 using a one-step spin coating method at a spin coating speed of 1000-6000 rpm / min for 5-60 s to prepare a hole transport layer;

[0076] 8. Evaporate a 30-200 nm gold / silver electrode or scrape a carbon electrode on the hole transport layer of step 7 to prepare an inorganic perovskite solar cell.

[0077] Experimental results: Conduct performance tests on solar cells, such as Figure 5 As shown, at AM1.5, 100mW / cm 2 Under standard light intensity, the open circuit voltage of the solar cell prepared in this embodiment is 1.308V and the short circuit current density is 19.72mA / cm 2 , fill factor 78.95% and efficiency 20.33%.

[0078] Example 5:

[0079] The present invention provides an axially symmetric small molecule-assisted crystallization inorganic perovskite solar cell and a preparation method thereof, comprising the following steps:

[0080] 1. Place the ITO / FTO conductive glass substrate (2×2cm 2 ) ultrasonically clean the substrate with detergent, deionized water, and isopropyl alcohol for 15 min, blow dry the moisture with nitrogen, and treat the substrate with UV-ozone for 20 min to obtain a clean and well-wettable ITO / FTO conductive glass substrate;

[0081] 2. Mix deionized water and SnO2 colloid in a volume ratio of 3:1 to obtain a SnO2 colloid solution (only SnO2 is used as an example here);

[0082] 3. Spin-coat the SnO2 colloidal solution prepared in step 2 onto the ITO / FTO conductive glass substrate prepared in step 1 at a speed of 3000 rpm / min for 30 seconds; then anneal at 180°C in ambient air for 30 minutes to obtain an electron transport layer.

[0083] 4. Dissolve CsI, HPbI3, PbBr2, and CsBr in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide at a certain molar ratio, and add 2.0 mg / mL of 2,6-pyridinedicarboxamide as an additive. Then, heat and stir at 60°C in a nitrogen environment until completely dissolved, to obtain a CsPbI solution containing 2.0 mg / mL of 2,6-pyridinedicarboxamide at a concentration of 0.6 mol / L. x Br 3-x Perovskite precursor solution;

[0084] 5. Spin-coat the perovskite solution obtained in step 4 on the electron transport layer obtained in step 3 at a speed of 500-9000 rpm / min for 10-120 s; then anneal in a nitrogen environment at 30-120° C. for 0.5-30 min, and anneal in ambient air at 150-350° C. for 1-30 min to obtain a perovskite absorption layer;

[0085] 6. Add 72.3 mg of Spiro-OMeTAD, 35 μL of LiTFSI solution (260 mg of LiTFSI powder dissolved in 1 mL of acetonitrile), and 30 μL of 4-tert-butylpyridine to 1 mL of chlorobenzene and stir until completely dissolved to obtain a hole transport layer precursor solution (Here, only Spiro-OMeTAD is used as an example);

[0086] 7. Spin-coat the hole transport layer precursor solution obtained in step 6 on the perovskite absorption layer prepared in step 5 using a one-step spin coating method at a spin coating speed of 1000-6000 rpm / min for 5-60 s to prepare a hole transport layer;

[0087] 8. Evaporate a 30-200 nm gold / silver electrode or scrape a carbon electrode on the hole transport layer of step 7 to prepare an inorganic perovskite solar cell.

[0088] Experimental results: Conduct performance tests on solar cells, such as Figure 6 As shown, at AM1.5, 100mW / cm 2 Under standard light intensity, the open circuit voltage of the solar cell prepared in this embodiment is 1.315V and the short circuit current density is 20.27mA / cm 2 , fill factor 78.76% and efficiency 20.97%.

[0089] Example 6:

[0090] The present invention provides an axially symmetric small molecule-assisted crystallization inorganic perovskite solar cell and a preparation method thereof, comprising the following steps:

[0091] 1. Place the ITO / FTO conductive glass substrate (2×2cm 2 ) ultrasonically clean the substrate with detergent, deionized water, and isopropyl alcohol for 15 min, blow dry the moisture with nitrogen, and treat the substrate with UV-ozone for 20 min to obtain a clean and well-wettable ITO / FTO conductive glass substrate;

[0092] 2. Mix deionized water and SnO2 colloid in a volume ratio of 3:1 to obtain a SnO2 colloid solution (only SnO2 is used as an example here);

[0093] 3. Spin-coat the SnO2 colloidal solution prepared in step 2 onto the ITO / FTO conductive glass substrate prepared in step 1 at a speed of 3000 rpm / min for 30 seconds; then anneal at 180°C in ambient air for 30 minutes to obtain an electron transport layer.

[0094] 4. Dissolve CsI, HPbI3, PbBr2, and CsBr in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide at a certain molar ratio, and add 2.0 mg / mL of 2,6-pyridinedicarboxamide as an additive. Then, heat and stir at 60°C in a nitrogen environment until completely dissolved, to obtain a CsPbI solution containing 2.0 mg / mL of 2,6-pyridinedicarboxamide at a concentration of 0.8 mol / L. x Br 3-x Perovskite precursor solution;

[0095] 5. Spin-coat the perovskite solution obtained in step 4 on the electron transport layer obtained in step 3 at a speed of 500-9000 rpm / min for 10-120 s; then anneal in a nitrogen environment at 30-120° C. for 0.5-30 min, and anneal in ambient air at 150-350° C. for 1-30 min to obtain a perovskite absorption layer;

[0096] 6. Add 72.3 mg of Spiro-OMeTAD, 35 μL of LiTFSI solution (260 mg of LiTFSI powder dissolved in 1 mL of acetonitrile), and 30 μL of 4-tert-butylpyridine to 1 mL of chlorobenzene and stir until completely dissolved to obtain a hole transport layer precursor solution (Here, only Spiro-OMeTAD is used as an example);

[0097] 7. Spin-coat the hole transport layer precursor solution obtained in step 6 on the perovskite absorption layer prepared in step 5 using a one-step spin coating method at a spin coating speed of 1000-6000 rpm / min for 5-60 s to prepare a hole transport layer;

[0098] 8. Evaporate a 30-200 nm gold / silver electrode or scrape a carbon electrode on the hole transport layer of step 7 to prepare an inorganic perovskite solar cell.

[0099] Experimental results: Conduct performance tests on solar cells, such as Figure 7 As shown, at AM1.5, 100mW / cm 2 Under standard light intensity, the open circuit voltage of the solar cell prepared in this embodiment is 1.267V and the short circuit current density is 20.23mA / cm 2 , filling factor 77.37% and efficiency 19.84%.

[0100] Comparative Example:

[0101] The present invention provides an inorganic perovskite solar cell based on non-axisymmetric small molecule-assisted crystallization and a preparation method thereof, comprising the following steps:

[0102] 1. Place the ITO / FTO conductive glass substrate (2×2cm 2 ) ultrasonically clean the substrate with detergent, deionized water, and isopropyl alcohol for 15 min, blow dry the moisture with nitrogen, and treat the substrate with UV-ozone for 20 min to obtain a clean and well-wettable ITO / FTO conductive glass substrate;

[0103] 2. Mix deionized water and SnO2 colloid in a volume ratio of 3:1 to obtain a SnO2 colloid solution (only SnO2 is used as an example here);

[0104] 3. Spin-coat the SnO2 colloidal solution prepared in step 2 onto the ITO / FTO conductive glass substrate prepared in step 1 at a speed of 3000 rpm / min for 30 seconds; then anneal at 180°C in ambient air for 30 minutes to obtain an electron transport layer.

[0105] 4. CsI, HPbI3, PbBr2 and CsBr were dissolved in a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide in a certain molar ratio. Then, the mixture was heated and stirred at 60°C in a nitrogen environment until it was completely dissolved to obtain CsPbI with a concentration of 0.8 mol / L. x Br 3-x Perovskite precursor solution;

[0106] 5. Spin-coat the perovskite solution obtained in step 4 on the electron transport layer obtained in step 3 at a speed of 500-9000 rpm / min for 10-120 s; then anneal in a nitrogen environment at 30-120° C. for 0.5-30 min, and anneal in ambient air at 150-350° C. for 1-30 min to obtain a perovskite absorption layer;

[0107] 6. Add 72.3 mg of Spiro-OMeTAD, 35 μL of LiTFSI solution (260 mg of LiTFSI powder dissolved in 1 mL of acetonitrile), and 30 μL of 4-tert-butylpyridine to 1 mL of chlorobenzene and stir until completely dissolved to obtain a hole transport layer precursor solution (Here, only Spiro-OMeTAD is used as an example);

[0108] 7. Spin-coat the hole transport layer precursor solution obtained in step 6 on the perovskite absorption layer prepared in step 5 using a one-step spin coating method at a spin coating speed of 1000-6000 rpm / min for 5-60 s to prepare a hole transport layer;

[0109] 8. Evaporate a 30-200 nm gold / silver electrode or scrape a carbon electrode on the hole transport layer of step 7 to prepare an inorganic perovskite solar cell.

[0110] Experimental results: Conduct performance tests on solar cells, such as Figure 8 As shown, at AM1.5, 100mW / cm 2 Under standard light intensity, the open circuit voltage of the solar cell prepared in this embodiment is 1.238V and the short circuit current density is 20.25mA / cm 2 , fill factor 78.78% and efficiency 19.75%.

[0111] In summary, an inorganic perovskite solar cell assisted by crystallization of an axisymmetric small molecule and a preparation method thereof are provided. The axisymmetric small molecule 2,6-pyridinedicarboxamide is introduced into the perovskite precursor solution and a thin film is deposited using a one-step spin coating method, and annealed to obtain an inorganic perovskite absorption layer. During the annealing process, the amide and pyridine groups in the 2,6-pyridinedicarboxamide structure form an interaction force with different lead groups in the inorganic perovskite. Through the modulation effect between the molecule and the perovskite, the perovskite crystal plane orientation is adjusted and the grain size is increased, which plays a role in in-situ passivation and improving the crystallization quality, and effectively suppresses the unfavorable phase change process, and finally obtains an efficient and stable inorganic perovskite solar cell. The introduced axisymmetric small molecule 2,6-pyridinedicarboxamide acts as shown in the attached figure. Figure 9 shown.

[0112] The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. The electron transport layer in the above embodiments only takes SnO2 as an example, and the hole transport layer only takes Spiro-OMeTAD as an example to illustrate the embodiment of the present invention, which does not limit the present invention. The electron transport layer selects TiO2, ZnO, and the hole transport layer selects Spiro-TTB, PTAA, CuSCN or P3HT, and the technical effects achieved are the same as those in the above embodiments. Any changes or replacements that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for preparing an axially symmetric small molecule-assisted crystallization inorganic perovskite solar cell, characterized in that: Adding an axially symmetrical small molecule to a perovskite precursor solution; the molecule is 2,6-pyridinedicarboxamide; The following steps are involved: (1) Preparing an electron transport layer on a transparent conductive substrate; (2) spin-coating an inorganic perovskite precursor solution containing an axisymmetric small molecule on the electron transport layer, and preparing a perovskite absorption layer after annealing; (3) preparing a hole transport layer on the perovskite absorption layer; (4) preparing a metal / carbon electrode on the hole transport layer; By introducing the axisymmetric small molecule 2,6-pyridinedicarboxamide into the perovskite precursor solution and preparing the perovskite film by spin coating, the obtained perovskite absorption layer has 2,6-pyridinedicarboxamide molecules; The concentration of the axisymmetric small molecule in the perovskite precursor solution is 0.5-15 mg / mL; The solvent of the perovskite precursor solution is a mixed solution of N,N-dimethylformamide and dimethyl sulfoxide, and the solute is CsPbI x Br 3-x Wherein 0≤X≤3; the concentration of the solute is 0.2-1.5 mol / L; The perovskite absorption layer is prepared by spin coating a perovskite precursor solution and then annealing it. The spin coating speed is 500-5000 rpm / min and the time is 20-120 seconds. The annealing conditions are: annealing at 30-120°C in a nitrogen environment for 0.5-30 minutes, followed by annealing at 150-350°C in ambient air for 1-30 minutes. The perovskite absorption layer is CsPbI with a thickness of 100-800 nm. x Br 3-x Inorganic perovskite thin films with a band gap of 1.68-2.30 eV.

2. The preparation method according to claim 1, wherein The transparent conductive substrate is ITO / FTO conductive glass; the electron transport layer is TiO2, SnO2 or ZnO and related composites; the hole transport layer is Spiro-OMeTAD, Spiro-TTB, PTAA, CuSCN or P3HT; and the metal electrode is gold, silver or carbon electrode.

3. The inorganic perovskite solar cell obtained by the preparation method according to claim 1 or 2, characterized in that: The structure of the inorganic perovskite solar cell is stacked in sequence from bottom to top: a transparent conductive substrate, an electron transport layer, a perovskite absorption layer, a hole transport layer and a metal electrode; the perovskite absorption layer has 2,6-pyridinedicarboxamide molecules.

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