Perovskite solar cell and crystal surface defect passivation method thereof

Abstract

The invention belongs to the technical field of solar cell preparation, and discloses a perovskite solar cell and a crystal surface defect passivation method thereof.The internal structure of the perovskite solar cell sequentially comprises a transparent conductive substrate layer, an electron transport layer, a perovskite light absorption layer, a passivation layer, a hole transport layer and a metal electrode layer from bottom to top; wherein the passivation layer is obtained by passivating perovskite crystals on the surface of the perovskite light absorption layer by a benzotriazole halogenated derivative. According to the invention, the surface defect density of the perovskite crystal passivated by using the benzotriazole derivative is reduced, so that the non-radiative recombination phenomenon of the perovskite solar cell is reduced; and meanwhile, the charge transmission capability at the interface of the perovskite light absorption layer and the passivation layer is not influenced, so that the photoelectric conversion efficiency of the perovskite solar cell is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell preparation, and in particular to a perovskite solar cell and a method for passivating crystal surface defects thereof. Background Art

[0002] After more than a decade of development, the photoelectric conversion efficiency of perovskite solar cells has increased from the initial 3.9% to 26.7%. Titanium ore solar cells have superior optical properties, low processing costs, simple preparation processes, etc., and are constantly undergoing commercial development. Positive devices are a conventional structure of perovskite solar cells. Its basic structure is a transparent conductive electrode layer, an electron transport layer, a perovskite active layer, a hole transport layer, and a metal electrode layer. The interface contact between the perovskite active layer and the transport layer directly affects the performance of the battery. There are many defects on the crystal surface of perovskite, including three-dimensional lead clusters produced by uncoordinated lead iodide and two-dimensional defects at the grain boundaries and crystal surfaces. At the same time, lithium ions in the upper hole transport layer and metal ion impurities diffused from the electrode will also form adjacent layer defects. These defects restrict the efficiency breakthrough and further industrialization of positive perovskite solar cells.

[0003] For example, the patent document with publication number CN117560937A discloses "a perovskite solar cell based on 3-methoxyphenylethylamine passivator and its preparation method", in which the perovskite solar cell uses 3-methoxyphenylethylamine as a surface passivator. After passivation with 3-methoxyphenylethylamine, the defect state density on the perovskite interface can be effectively reduced, solving the problem that the existing perovskite solar cell has uncoordinated Pb 2+ This leads to low photoelectric conversion efficiency and poor stability. The order of the perovskite solar cell from bottom to top is: FTO glass as a conductive cathode, tin oxide deposited on the FTO layer by a chemical bath as an electron transport layer, a perovskite absorption layer spin-coated by a one-step method, 3-methoxyphenylethylamine spin-coated on the perovskite absorption layer as a passivation layer, spin-coated spiro-OMeTAD as a hole transport layer, and a metal anode electrode by vacuum thermal evaporation.

[0004] For example, the patent document with publication number CN118870929A discloses "a method for preparing a perovskite solar cell", which is to sequentially form a hole transport layer, a lower interface passivation layer, a perovskite light absorption layer, an upper interface passivation layer, an electron transport layer, an electron buffer layer and a metal electrode layer on the surface of a conductive glass substrate. The invention uses the passivating agent phenylethyl iodide amine and methylamine ethanol solution to synergistically passivate the upper interface of the perovskite solar cell. MA induces grain boundary migration and regrowth of perovskite grains, while promoting the penetration of the passivating molecule phenylethylamine into the buried interface for deep passivation and reducing non-radiative recombination centers. Moreover, the low production cost and simple operation are more conducive to actual production, providing an important reference for the industrialization of perovskite solar cells.

[0005] For example, the patent document with publication number CN118946176A discloses "a dual-effect modifier passivated perovskite solar cell". The core of the perovskite solar cell lies in the efficient perovskite light-absorbing layer, which can absorb wide-band sunlight and generate photogenerated carriers. However, there are a large number of defects on the surface and grain boundaries of the perovskite material, which become the center of carrier recombination and reduce the photoelectric conversion efficiency. The (1H-benzimidazole-2-yl)-methylamine hydrochloride dual-effect modifier used above has a specific functional group in its molecular design, which can effectively combine with the defects on the perovskite surface to form a stable chemical bond, thereby passivating these defects, reducing non-radiative recombination, and improving the collection efficiency of photogenerated carriers.

[0006] In the prior art disclosed above, the common passivation method for such defects is to use organic ammonium salts such as phenylethylammonium iodide (PEAI) or some two-dimensional materials such as graphene and transition metal sulfides to passivate the defects on the crystal surface. However, these passivation methods may affect the extraction and transmission of charge carriers, and sometimes may introduce new defects or unstable phases. And its compatibility with perovskite and interface stability are also a challenge. Summary of the invention

[0007] Defects on the surface of perovskite crystals affect the performance of perovskite solar cells. Currently common passivation methods such as organic ammonium salt treatment will affect the extraction and transmission of carriers, thereby reducing the current of the device. In addition, the perovskite / hole passivation methods commonly used in positive devices currently do not take into account the problem of ion migration from the electrode. The purpose of the present invention is to provide a perovskite solar cell and a method for passivating crystal surface defects, which can not only passivate the lead clusters on the surface of the perovskite, but also complex the metal ions from the electrode, thereby improving the efficiency of the device while improving its stability. To achieve the above purpose, the present invention provides the following technical solutions:

[0008] The present invention provides a perovskite solar cell, the internal structure of which comprises, from bottom to top, a transparent conductive substrate layer, an electron transport layer, a perovskite light absorption layer, a passivation layer, a hole transport layer and a metal electrode layer; wherein the passivation layer is obtained by passivating perovskite crystals on the surface of the perovskite light absorption layer with a benzotriazole halogenated derivative.

[0009] Furthermore, the transparent conductive substrate layer is FTO conductive glass.

[0010] Furthermore, the electron transport layer is a metal oxide SnO 2 、TiO 2 , ZnO or AZO.

[0011] Furthermore, the general structural formula of the perovskite in the perovskite light absorbing layer is Cs x MA y FA 1-x-y Pb(I a Br 1-a ) 3 .

[0012] Furthermore, the passivation layer uses benzotriazole halogenated derivatives to passivate the perovskite crystals on the surface of the perovskite light absorbing layer; wherein,

[0013] The benzotriazole halogenated derivative is one of 5,6-difluorobenzotriazole, 5,6-dichlorobenzotriazole, 5,6-diiodobenzotriazole, 4,7-difluorobenzotriazole, 4,7-dichlorobenzotriazole or 4,7-diiodobenzotriazole.

[0014] Furthermore, the hole transport layer is Spiro-OMeTAD.

[0015] Furthermore, the metal electrode layer is a metal material or a transparent metal oxide, and its thickness is 60 to 150 nm;

[0016] in,

[0017] The metal material is one of Au, Ag, Al or Cu;

[0018] The transparent metal oxide is one of ITO and AZO.

[0019] The present invention also provides a method for passivating crystal surface defects of a perovskite solar cell, the method comprising the following steps:

[0020] Step S1, pretreatment of the transparent conductive substrate layer: ultrasonically clean the transparent electrode with deionized water, isopropyl alcohol, and acetone in sequence, dry the cleaned transparent conductive substrate layer with an oven or blow dry with an air gun, and use plasma cleaning for 10 to 30 minutes;

[0021] Step S2, preparing an electron transport layer: preparing an electron transport layer on the pretreated transparent conductive substrate layer by coating and annealing processes;

[0022] Step S3, preparation of a perovskite light absorbing layer: preparing a perovskite light absorbing layer on the electron transport layer by a solution method;

[0023] Step S4, preparation of a passivation layer: using a spin coating and thermal annealing process to passivate the perovskite crystals on the surface of the perovskite light absorbing layer using a benzotriazole halogenated derivative;

[0024] Step S5, hole transport layer preparation: a Spiro-OMeTAD hole transport layer is prepared on the passivation layer by a coating process, and after the preparation is completed, the layer is oxidized in a dry air environment for 2 to 10 hours;

[0025] Step S6, preparation of a metal electrode layer: depositing a metal material or a transparent metal oxide on the hole transport layer to prepare a metal electrode layer.

[0026] Furthermore, in the preparation of the electron transport layer, the coating process is a spin coating method; the spin coating rate is 1000 to 5000 rpm, and the time is 20 to 60 s;

[0027] The concentration of the spin coating solution prepared by the metal oxide in the electron transport layer (2) is 0.5 to 10 mg / mL;

[0028] The annealing process includes: a temperature of 120 to 180° C. and a time of 10 to 60 minutes.

[0029] Furthermore, in the preparation of the perovskite light absorbing layer, the solution method is a two-step solution method;

[0030] First, lead iodide (PbI) was spin-coated on the electron transport layer using a solution method. 2 ) or lead bromide (PbBr 2 ) solution, the concentration is 0.5-1.5M, the solvent is one or more of DMF, DMSO, NMP, the spin coating rate is 2000-5000rpm, the time is 20-60s, and then annealing treatment is performed, the annealing temperature is 70-150°C, and the annealing time is 1-10min, to obtain a dense lead halide film;

[0031] Then, a layer of organic salt is spin-coated on the lead halide film by a solution method, wherein the organic salt is FAI and / or MAI, the solvent is IPA, the concentration is 80-120 mg / mL, the spin-coating rate is 2000-5000 rpm, the time is 20-60 seconds, and an annealing treatment is performed after the spin-coating is completed, the annealing temperature is 70-150° C., and the annealing time is 5-60 minutes;

[0032] The thickness of the perovskite light-absorbing layer (3) is 200-800 nm.

[0033] Furthermore, in the preparation of the passivation layer, the concentration of the benzotriazole halogenated derivative solution after the benzotriazole halogenated derivative is dissolved in a solvent is 0.5 to 5 mg / mL, and the solvent for dissolving the benzotriazole halogenated derivative is one or more of isopropanol, methanol, ethanol, chlorobenzene, chloroform, and anisole;

[0034] The coating process is a spin coating method, the spin coating rate is 2000-6000 rpm, and the time is 20-60s;

[0035] The annealing process includes: an annealing temperature of 70 to 120° C. and an annealing time of 1 to 10 minutes.

[0036] Furthermore, in the preparation of the hole transport layer, the concentration of the Spiro-OMeTAD is 0.1 to 1 M;

[0037] The coating process is a spin coating method, the spin coating rate is 1000-4000 rpm, and the time is 20-60s.

[0038] Furthermore, the thickness of the metal electrode layer (6) is 60 to 150 nm.

[0039] Technical effects and advantages of the present invention:

[0040] The present invention uses benzotriazole halogenated derivatives to passivate the defects on the surface of perovskite crystals. Benzotriazole materials are often used as one of the donor materials of DA structure polymers and have excellent electron donating ability. Its structure is rich in heteroatom N and has abundant lone electrons, which can coordinate with lead clusters on the surface of perovskite to passivate defects, and can also react with metal ions such as Ag diffused into the perovskite. + , Cu + The complexes form dimers, which hinder their further diffusion into the perovskite. Moreover, as a common electron-donating unit, benzotriazole materials have excellent hole extraction and transfer capabilities, which will not affect the charge extraction of the battery, and will not cause a decrease in current while passivating the perovskite crystal defects. The surface defect density of the perovskite crystal passivated with benzotriazole derivatives is reduced, which reduces the non-radiative recombination phenomenon of the perovskite solar cell. At the same time, the charge transfer capacity at the interface between the perovskite light-absorbing layer and the passivation layer is not affected, thereby improving the photoelectric conversion efficiency of the perovskite solar cell.

[0041] Other features and advantages of the present invention will be described in the following description, and partly become obvious from the description, or be understood by implementing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0043] Figure 1 A structural diagram of a perovskite solar cell provided by the present invention;

[0044] Figure 2 A flow chart of a perovskite solar cell and a method for passivating crystal surface defects thereof provided by the present invention;

[0045] Figure 3 This is a comparison diagram of the efficiency of perovskite solar cells before and after passivation using 5,6-difluorobenzotriazole in an embodiment of the present invention;

[0046] Figure 4 This is a comparison diagram of UV aging of perovskite solar cells before and after passivation with 5,6-difluorobenzotriazole in an embodiment of the present invention;

[0047] Description of the drawings: 1. Transparent conductive substrate layer; 2. Electron transport layer; 3. Perovskite light absorption layer; 4. Passivation layer; 5. Hole transport layer; 6. Metal electrode layer. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the steps. For example, some steps may be decomposed, while some steps may be combined or partially combined, so the actual execution order may change according to the actual situation.

[0050] The terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein.

[0051] In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or sub-modules is not necessarily limited to those steps or sub-modules explicitly listed, but may include other steps or sub-modules not explicitly listed or inherent to these processes, methods, products, or apparatuses.

[0052] In order to solve the deficiencies of the prior art, the present invention discloses a perovskite solar cell. Figure 1 The structural diagram of the perovskite solar cell provided by the present invention is as follows: Figure 1 As shown, the internal structure of the perovskite solar cell includes, from bottom to top, a transparent conductive substrate layer 1, an electron transport layer 2, a perovskite light absorption layer 3, a passivation layer 4, a hole transport layer 5 and a metal electrode layer 6; wherein the passivation layer (4) is obtained by passivating the perovskite crystals on the surface of the perovskite light absorption layer (3) with a benzotriazole halogenated derivative;

[0053] Exemplarily, the transparent conductive substrate layer 1 is FTO conductive glass (fluorine-doped tin oxide conductive glass);

[0054] The electron transport layer 2 may be SnO 2 、TiO 2 , ZnO, AZO and other metal oxides;

[0055] The general structural formula of the perovskite in the perovskite light absorbing layer 3 is Cs x MA y FA 1-x-y Pb(I a Br 1-a ) 3 ;

[0056] The passivation layer 4 uses a benzotriazole halogenated derivative to passivate the perovskite crystals on the surface of the perovskite light absorbing layer 3; wherein the benzotriazole halogenated derivative includes one of 5,6-difluorobenzotriazole, 5,6-dichlorobenzotriazole, 5,6-diiodobenzotriazole, 4,7-difluorobenzotriazole, 4,7-dichlorobenzotriazole or 4,7-diiodobenzotriazole;

[0057] The hole transport layer 5 is Spiro-OMeTAD;

[0058] The metal electrode layer 6 is a metal material or a transparent metal oxide; wherein the metal material may be Au, Ag, Al, Cu, etc., and the transparent metal oxide may be ITO, AZO, etc.

[0059] The present invention also discloses a perovskite solar cell and a method for passivating crystal surface defects thereof. Figure 2 The flow chart of the perovskite solar cell and the crystal surface defect passivation method provided by the present invention is as follows: Figure 2 As shown, the method comprises the following steps:

[0060] Step S1, pretreatment of the transparent conductive substrate layer 1: ultrasonically clean the transparent electrode with deionized water, isopropyl alcohol and acetone in sequence, dry the cleaned transparent conductive substrate layer 1 with an oven or blow dry with an air gun, and use plasma cleaning for 10 min to 30 min.

[0061] Step S2, preparation of electron transport layer 2: on the pre-treated transparent conductive substrate layer 1, a coating process and an annealing process are used to prepare an electron transport layer 2, wherein the electron transport layer 2 may be SnO 2 、TiO 2 , ZnO, AZO and other metal oxides; the concentration of the spin coating liquid prepared by the metal oxide in the electron transport layer (2) is 0.5-10 mg / mL;

[0062] The coating process is a spin coating method; the spin coating rate is 1000-5000 rpm, and the time is 20-60 s;

[0063] The annealing process includes: a temperature of 120 to 180° C. and a time of 10 to 60 minutes.

[0064] Step S3, preparation of perovskite light absorbing layer 3: preparing perovskite light absorbing layer 3 on the electron transport layer 2 by solution method, wherein the general structural formula of perovskite in the perovskite light absorbing layer 3 is Cs x MA y FA 1-x-y Pb(I a Br 1-a ) 3 ;in,

[0065] The solution method is a two-step solution method: first, lead iodide (PbI) is spin-coated on the electron transport layer by spin coating. 2 ) or lead bromide (PbBr 2) solution, the concentration is 0.5-1.5M, the solvent is one or more of DMF, DMSO, NMP, the spin coating rate is 2000-5000rpm, the time is 1000-5000rpm, and then annealing is performed, the annealing temperature is 70-150°C, and the annealing time is 1-10min, to obtain a dense lead halide film. Then, a layer of organic salt is spin-coated on the lead halide film by spin coating, the organic salt is one or more of FAI and MAI, the solution is IPA, the concentration is 80-120mg / mL, the spin coating rate is 2000-5000rpm, the time is 1000-5000rpm, and after the spin coating is completed, annealing is performed, the annealing temperature is 70-150°C, and the annealing time is 5-60min;

[0066] The thickness of the perovskite light-absorbing layer (3) is 200-800 nm.

[0067] Step S4, preparation of the passivation layer 4: passivating the perovskite crystals on the surface of the perovskite light absorbing layer 3 using a coating process and a thermal annealing process using a benzotriazole halogenated derivative; wherein,

[0068] The concentration of the benzotriazole halogenated derivative solution after dissolving the benzotriazole halogenated derivative in a solvent is 0.5 to 5 mg / mL, and the solvent for dissolving the benzotriazole halogenated derivative can be one or more of isopropanol, methanol, ethanol, chlorobenzene, chloroform, and anisole;

[0069] The coating process is a spin coating method, the spin coating rate is 2000-6000rpm, and the time is 1000-5000rpm;

[0070] The annealing process includes: an annealing temperature of 70 to 120° C. and an annealing time of 1 to 10 minutes.

[0071] Step S5, preparation of hole transport layer 5: Prepare Spiro-OMeTAD hole transport layer 5 on the passivation layer 4 by coating process, with a concentration of 0.1-1M, a spin coating rate of 1000-4000rpm, and a time of 20-60s. After preparation, oxidize in a dry air environment for 2-10h.

[0072] Step S6, preparation of metal electrode layer 6: depositing metal material or transparent metal oxide on the hole transport layer 5 to prepare metal electrode layer 6, the metal material can be Au, Ag, Al, Cu, etc., the transparent metal oxide can be ITO, AZO, etc., and its thickness is 60 to 150 nm.

[0073] The technical solution of the present invention is further explained and illustrated below in conjunction with specific embodiments.

[0074] Embodiment 1:

[0075] Embodiment 1 of the present invention provides a perovskite solar cell and a method for passivating crystal surface defects thereof, the method comprising the following steps:

[0076] Step S1, pretreatment of transparent conductive substrate layer 1: ultrasonically clean a 6*6 cm FTO (fluorine-doped tin oxide conductive glass) substrate with deionized water, isopropanol, and acetone in turn for 15 min each, then blow dry the FTO substrate with nitrogen and plasma treat for 30 min.

[0077] Step S2, preparation of electron transport layer 2: preparing SnO on the pretreated FTO conductive substrate layer 1 2 As the electron transport layer 2, the SnO 2 The concentration was 4 mg / mL, and it was spin-coated on FTO at 4000 rpm for 30 s and then transferred to a hot stage at 150 °C for annealing for 15 min.

[0078] Step S3, preparation of perovskite light absorbing layer 3: 1 mmol of PbBr 2 Dissolve in 1 mL DMF: NMP = 4:1 (v / v) mixed solvent, heat and stir at 60 °C for 2 h, take 500 μL PbBr 2 The precursor solution was spin-coated on the electron transport layer 2 at a speed of 4000 rpm for 60 s. After the spin coating, the substrate was annealed at 120 ° C for 10 min to obtain PbBr 2 Take 500 μL FAI in IPA solution and spin coat it at 3000 r / s for 60 s on PbBr 2 The film is then placed on a hot plate for annealing at 120°C for 10 minutes to obtain a dense perovskite light-absorbing layer 3.

[0079] Step S4, preparation of passivation layer 4: dissolve 1 mg of 5,6-difluorobenzotriazole in 1 mL of IPA, stir for 1 hour, and then spin-coat the perovskite light absorbing layer 3 at a speed of 5000 rpm for 30 seconds, and then anneal on a hot plate at 100° C. for 10 minutes to obtain passivation layer 4.

[0080] Step S5, preparation of hole transport layer 5: Spiro-OMeTAD was dissolved in chlorobenzene at a concentration of 78 mg / mL, and 1M Li-TFSI acetonitrile solution and TBP were added as additives at concentrations of 40 μL / mL and 17 μL / mL, respectively. After stirring for 1 hour, the mixture was spin-coated at a speed of 3000 rpm for 30 seconds, and then placed in a light-proof air drying oven for oxidation for 10 hours to obtain hole transport layer 5.

[0081] Step S6, preparation of metal electrode layer 6: Place the battery with prepared hole transport layer 5 into a vacuum thermal evaporator at 4E-4 120 nm Ag was deposited under vacuum of 1.5 Pa as electrode.

[0082] Embodiment 2:

[0083] Embodiment 2 of the present invention provides a perovskite solar cell and a method for passivating crystal surface defects thereof, the method comprising the following steps:

[0084] Step S1, pretreatment of transparent conductive substrate layer 1: ultrasonically clean a 6*6 cm FTO (fluorine-doped tin oxide conductive glass) substrate with deionized water, isopropanol, and acetone in turn for 15 min each, then blow dry the FTO substrate with nitrogen and plasma treat for 30 min.

[0085] Step S2, preparation of electron transport layer 2: preparing SnO on the pretreated FTO conductive substrate layer 1 2 As the electron transport layer, the SnO 2 The concentration was 4 mg / mL, and it was spin-coated on FTO at 4000 rpm for 30 s and then transferred to a hot stage at 150 °C for annealing for 15 min.

[0086] Step S3, preparation of perovskite light absorbing layer 3: 1 mmol of PbBr 2 Dissolve in 1 mL DMF: NMP = 4:1 (v / v) mixed solvent, heat and stir at 60 °C for 2 h, take 500 μL PbBr 2 The precursor solution was spin-coated on the electron transport layer 2 at a speed of 4000 rpm for 60 s. After the spin coating, the substrate was annealed at 120 ° C for 10 min to obtain PbBr 2 Take 500 μL FAI in IPA solution and spin coat it at 3000 r / s for 60 s on PbBr 2 The film is then placed on a hot plate for annealing at 120°C for 10 minutes to obtain a dense perovskite light-absorbing layer 3.

[0087] Step S4, preparation of passivation layer 4: dissolve 2 mg of 5,6-dichlorobenzotriazole in 1 mL of IPA, stir for 1 hour, and then spin-coat the perovskite light absorbing layer 3 at a speed of 4500 rpm for 30 seconds, and then anneal on a hot plate at 100° C. for 10 minutes to obtain a passivation layer 4.

[0088] Step S5, preparation of hole transport layer 5: Spiro-OMeTAD was dissolved in chlorobenzene at a concentration of 78 mg / mL, and 1M Li-TFSI acetonitrile solution and TBP were added as additives at concentrations of 40 μL / mL and 17 μL / mL, respectively. After stirring for 1 hour, the mixture was spin-coated at a speed of 3000 rpm for 30 seconds, and then placed in a light-proof air drying oven for oxidation for 10 hours to obtain hole transport layer 5.

[0089] Step S6, preparation of metal electrode layer 6: Place the battery with prepared hole transport layer 5 into a vacuum thermal evaporator at 4E -4 100 nm Au was deposited under a vacuum of 1.3 Pa as an electrode.

[0090] Embodiment 3:

[0091] Embodiment 3 of the present invention provides a perovskite solar cell and a method for passivating crystal surface defects thereof, the method comprising the following steps:

[0092] Step S1, pretreatment of transparent conductive substrate layer 1: ultrasonically clean a 6*6 cm FTO (fluorine-doped tin oxide conductive glass) substrate with deionized water, isopropanol, and acetone in turn for 15 min each, then blow dry the FTO substrate with nitrogen and plasma treat for 30 min.

[0093] Step S2, preparation of electron transport layer 2: preparing SnO on the pretreated FTO conductive substrate layer 1 2 As the electron transport layer 2, the SnO 2 The concentration was 3.5 mg / mL, and it was spin-coated on FTO at 4000 rpm for 30 s and then transferred to a hot stage at 150 °C for annealing for 15 min.

[0094] Step S3, preparation of perovskite light absorbing layer 3: 1 mmol of PbBr 2 Dissolve in 1 mL DMF: NMP = 4:1 (v / v) mixed solvent, heat and stir at 60 °C for 2 h, take 500 μL PbBr 2 The precursor solution was spin-coated on the electron transport layer 2 at a speed of 4000 rpm for 60 s. After the spin coating, the substrate was annealed at 120 ° C for 10 min to obtain PbBr 2 Take 500 μL FAI in IPA solution and spin coat it at 3000 r / s for 60 s on PbBr 2 The film is then placed on a hot plate for annealing at 120°C for 10 minutes to obtain a dense perovskite light-absorbing layer 3.

[0095] Step S4, preparation of passivation layer 4: dissolve 1 mg of 4,7-difluorobenzotriazole in 1 mL of IPA, stir for 1 hour, and then spin-coat the perovskite light absorbing layer 3 at a speed of 4500 rpm for 30 seconds, and then anneal on a hot plate at 100° C. for 10 minutes to obtain passivation layer 4.

[0096] Step S5, preparation of hole transport layer 5: Spiro-OMeTAD was dissolved in chlorobenzene at a concentration of 78 mg / mL, and 1M Li-TFSI acetonitrile solution and TBP were added as additives at concentrations of 40 μL / mL and 17 μL / mL, respectively. After stirring for 1 hour, the mixture was spin-coated at a speed of 3000 rpm for 30 seconds, and then placed in a light-proof air drying oven for oxidation for 10 hours to obtain hole transport layer 5.

[0097] Step S6, preparation of metal electrode layer 6: Place the battery with prepared hole transport layer 5 into a vacuum thermal evaporator at 4E -4 100 nm Au was deposited under a vacuum of 1.3 Pa as an electrode.

[0098] The passivation material of the present invention is used to passivate the perovskite crystal defects, and the photoelectric conversion efficiency is significantly improved compared with the unpassivated perovskite device. Figure 3 This is a comparison diagram of the efficiency of the perovskite solar cell before and after passivation using 5,6-difluorobenzotriazole in Example 1 of the present invention; Figure 3 As shown, the filling factor of the device is significantly improved, indicating that the contact at the interface is improved. At the same time, the current after passivation does not decrease, proving that the passivation method of the present invention has no effect on charge extraction. And the use of the passivation material of the present invention to passivate the perovskite crystal defects can hinder the migration of ions from the electrode, thereby improving stability.

[0099] Figure 4 This is a UV aging comparison diagram of the perovskite solar cell before and after passivation with 5,6-difluorobenzotriazole in Example 1 of the present invention; Figure 4 As shown, the passivated device can still maintain 96.5% of the initial efficiency after UV irradiation of about 115KWh, while the efficiency of the control group device has decayed to 76%.

[0100] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A perovskite solar cell, characterized in that: The internal structure of the perovskite solar cell comprises, from bottom to top, a transparent conductive substrate layer (1), an electron transport layer (2), a perovskite light absorption layer (3), a passivation layer (4), a hole transport layer (5) and a metal electrode layer (6); wherein the passivation layer (4) is obtained by passivating perovskite crystals on the surface of the perovskite light absorption layer (3) with a benzotriazole halogenated derivative.

2. The perovskite solar cell according to claim 1, characterized in that The transparent conductive substrate layer (1) is FTO conductive glass.

3. The perovskite solar cell according to claim 1 or 2, characterized in that: The electron transport layer (2) is one of the metal oxides SnO2, TiO2, ZnO or AZO.

4. The perovskite solar cell according to claim 2, characterized in that: The general structural formula of the perovskite in the perovskite light absorbing layer (3) is Cs x MA y FA 1-x-y Pb(I a Br 1-a )3.

5. The perovskite solar cell according to claim 1, characterized in that: The passivation layer (4) uses a benzotriazole halogenated derivative to passivate the perovskite crystals on the surface of the perovskite light absorbing layer (3); wherein: The benzotriazole halogenated derivative is one of 5,6-difluorobenzotriazole, 5,6-dichlorobenzotriazole, 5,6-diiodobenzotriazole, 4,7-difluorobenzotriazole, 4,7-dichlorobenzotriazole or 4,7-diiodobenzotriazole.

6. The perovskite solar cell according to claim 1, characterized in that: The hole transport layer (5) is Spiro-OMeTAD.

7. The perovskite solar cell according to claim 1, characterized in that: The metal electrode layer (6) is a metal material or a transparent metal oxide; wherein, The metal material is one of Au, Ag, Al or Cu; The transparent metal oxide is one of ITO and AZO.

8. A method for passivating crystal surface defects of a perovskite solar cell according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: Step S1, pretreatment of the transparent conductive substrate layer (1): ultrasonically clean the transparent electrode using deionized water, isopropyl alcohol, and acetone in sequence, dry the cleaned transparent conductive substrate layer (1) in an oven or blow dry it with an air gun, and use plasma cleaning for 10 to 30 minutes; Step S2, preparing the electron transport layer (2): preparing the electron transport layer (2) on the pretreated transparent conductive substrate layer (1) by coating and annealing processes; Step S3, preparation of a perovskite light absorbing layer (3): preparing a perovskite light absorbing layer (3) on the electron transport layer (2) by a solution method; Step S4, preparation of the passivation layer (4): using a spin coating and thermal annealing process to passivate the perovskite crystals on the surface of the perovskite light absorbing layer (3) using a benzotriazole halogenated derivative; Step S5, preparation of hole transport layer (5): preparing a Spiro-OMeTAD hole transport layer (5) on the passivation layer (4) by a coating process, and oxidizing it in a dry air environment for 2 to 10 hours after the preparation; Step S6, preparation of the metal electrode layer (6): depositing a metal material or a transparent metal oxide on the hole transport layer (5) to prepare the metal electrode layer (6).

9. The method for passivating crystal surface defects of a perovskite solar cell according to claim 8, characterized in that: In the preparation of the electron transport layer (2), the coating process is a spin coating method; the spin coating rate is 1000 to 5000 rpm, and the time is 20 to 60 seconds; The concentration of the spin coating solution prepared by the metal oxide in the electron transport layer (2) is 0.5 to 10 mg / mL; The annealing process includes: a temperature of 120 to 180° C. and a time of 10 to 60 minutes.

10. The method for passivating crystal surface defects of a perovskite solar cell according to claim 8, characterized in that: In the preparation of the perovskite light absorbing layer (3), the solution method is a two-step solution method; First, a lead iodide (PbI2) or lead bromide (PbBr2) solution is spin-coated on the electron transport layer (2) using a solution method, the concentration of which is 0.5 to 1.5 M, the solvent is one or more of DMF, DMSO, and NMP, the spin-coating speed is 2000 to 5000 rpm, the time is 20 to 60 seconds, and then an annealing treatment is performed, the annealing temperature is 70 to 150° C., and the annealing time is 1 to 10 minutes, to obtain a dense lead halide film; Then, a layer of organic salt is spin-coated on the lead halide film by a solution method, wherein the organic salt is FAI and / or MAI, the solvent is IPA, the concentration is 80-120 mg / mL, the spin-coating rate is 2000-5000 rpm, the time is 20-60 seconds, and an annealing treatment is performed after the spin-coating is completed, the annealing temperature is 70-150° C., and the annealing time is 5-60 minutes; The thickness of the perovskite light-absorbing layer (3) is 200-800 nm.

11. The method for passivating crystal surface defects of a perovskite solar cell according to claim 8, characterized in that: In the preparation of the passivation layer (4), the concentration of the benzotriazole halogenated derivative solution after dissolving the benzotriazole halogenated derivative in a solvent is 0.5 to 5 mg / mL, and the solvent for dissolving the benzotriazole halogenated derivative is one or more of isopropanol, methanol, ethanol, chlorobenzene, chloroform, and anisole; The coating process is a spin coating method, the spin coating rate is 2000-6000 rpm, and the time is 20-60s; The annealing process includes: an annealing temperature of 70 to 120° C. and an annealing time of 1 to 10 minutes.

12. The method for passivating crystal surface defects of a perovskite solar cell according to claim 8, characterized in that: In the preparation of the hole transport layer (5), the concentration of the Spiro-OMeTAD is 0.1 to 1 M; The coating process is a spin coating method, the spin coating rate is 1000-4000 rpm, and the time is 20-60s.

13. The method for passivating crystal surface defects of a perovskite solar cell according to claim 8, characterized in that: The thickness of the metal electrode layer (6) is 60-150 nm.

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