Hole transport layer, preparation method and trans-perovskite photovoltaic cell

Abstract

The invention provides a hole transport layer, a preparation method and a trans-perovskite photovoltaic cell, and relates to the technical field of perovskite photovoltaic cells. The hole transport layer is composed of self-assembled micromolecules and sulfydryl-containing organic matters; and the self-assembled small molecules are selected from one or a combination of two or more of MeO (MeO)-2PACz, MeO (4) PACz, MeOF (MeF)-4PACz, Me (Me4) PACz, Me (Me-2) PACz, MPA (MPa-BT)-CA (Methyl Phosphate), MPA-Ph (Methyl Phosphate)-CA, MTPA (Methyl Tetraacetic Acid)-BA, MC-43, EADR03, Br-2EPT (Br-2EPT) and CbzNaph. Preferably, the self-assembled micromolecules and the sulfydryl-containing organic matter are dissolved by adopting a mixed solvent, and the transition metal oxide layer is subjected to oxidation treatment by adopting an oxidizing agent. According to the invention, the combining capacity of the transition metal oxide layer and SAMs can be improved, and the photoelectric conversion efficiency can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of perovskite photovoltaic cells and relates to a hole transport layer, a preparation method and an inverse perovskite photovoltaic cell. Background Art

[0002] For inverse perovskite photovoltaic cells, self-assembled small molecule layers (SAMs) can greatly solve the problems of energy loss and insufficient carrier extraction, but it is often difficult to form a high-density, tightly packed SAMs layer. From the interface perspective, due to the irregular surface coverage of transparent conductive oxides (TCOs) such as indium tin oxide (ITO) and fluorine-doped tin oxide (FTO), the rough surface of TCO will lead to poor adhesion of SAMs, making it difficult to form sufficient coverage. From the bulk phase perspective, SAMs molecules tend to form micellar nanoparticles in solution rather than remain dispersed as single molecules. The limited solubility makes the chemical bonds formed by self-assembled small molecules and metal oxides insufficient, and these SAMs micelles require additional energy to decompose them when deposited on the substrate, resulting in defects, making it difficult for the lower interface to be tight and orderly.

[0003] The presence of high-order cluster dimers of these SAMs molecules will result in poor anchoring between them and the substrate, which will lead to obstructed hole transport and damage the carrier transport performance and photoelectric conversion efficiency of perovskite solar cells.

[0004] Therefore, despite the promising prospects of SAMs, achieving high-density, tightly packed SAMs remains challenging. Summary of the invention

[0005] In order to solve the above technical problems, the present invention proposes to improve the dispersibility of SAMs to form a stable interface, so as to significantly improve the photoelectric conversion efficiency of trans-perovskite. Based on this, the present invention provides a hole transport layer, a preparation method and a trans-perovskite photovoltaic cell.

[0006] The technical solution of the present invention is as follows:

[0007] A hole transport layer, the hole transport layer is composed of self-assembled small molecules and thiol-containing organic matter;

[0008] The self-assembling small molecule is selected from one or a combination of two or more of MeO-2PACz, MeO-4PACz, MeOF-4PACz, Me-4PACz, Me-2PACz, MPA-BT-CA, MPA-Ph-CA, MTPA-BA, MC-43, EADR03, Br-2EPT and CbzNaph.

[0009] Preferably, the structure of the thiol-containing organic compound is as shown in the following formula (1):

[0010] HSR 1 R 2 (1)

[0011] Among them, R 1 is absent, C1-C4 alkylene or arylene, R 2 Selected from -COOH, -OH, C1-C4 alkyl or -NH 2 .

[0012] Preferably, the weight ratio of the self-assembling small molecules to the thiol-containing organic matter is 0.01-0.1:1.

[0013] A method for preparing a hole transport layer according to any one of the above embodiments comprises the following steps:

[0014] Dissolving the self-assembled small molecule layer and the thiol-containing organic compound in a mixed solvent to obtain a precursor solution A;

[0015] The mixed solvent consists of a main solvent and a secondary solvent, and the polarity of the secondary solvent is greater than that of the main solvent;

[0016] The precursor solution A is deposited on the surface of the transition metal oxide layer and annealed to obtain the hole transport layer.

[0017] Preferably, the weight ratio of the main solvent to the secondary solvent is 9:1-49:1.

[0018] More preferably, the main solvent is selected from alcohol solvents.

[0019] More preferably, the secondary solvent is selected from one or a combination of two or more of DMSO, DMF, DMAc, acetonitrile and NMP.

[0020] Preferably, the content of the mercapto-containing organic matter in the precursor solution is 1-10 wt %.

[0021] An inverse perovskite photovoltaic cell comprises, from bottom to top, at least a conductive substrate layer, a composite hole transport layer, a perovskite layer, a passivation layer, an electron transport layer and a back electrode;

[0022] The composite hole transport layer comprises the hole transport layer described in any one of the above embodiments or a hole transport layer prepared by the method for preparing a hole transport layer described in any one of the above embodiments and a transition metal oxide layer, and the hole transport layer is located above the transition metal oxide layer.

[0023] Preferably, the transition metal oxide layer is composed of transition metal oxide nanoparticles oxidized by an oxidant.

[0024] The beneficial effects of the present invention are:

[0025] (1) The present invention adds thiol-containing organic matter to SAMs to decompose the high-order molecular clusters of self-assembled small molecules. The thiol group can reduce the aggregation of dimers, decompose the high-order clusters of self-assembled small molecules, and even the distribution of molecules, thereby solving the problem of self-assembled small molecules and bottom transition metal oxide bonding anchoring to the greatest extent. Moreover, the thiol group of the thiol-containing organic matter is embedded in the self-assembled small molecules to form a mixed layer, rather than forming a passivation layer on the surface of the self-assembled small molecules, which will not affect the crystallization and electron transmission of the overlying perovskite layer.

[0026] (2) The present invention adopts a mixed organic solvent strategy to dissolve the self-assembled small molecule layer. The solubility of the self-assembled small molecule layer in the secondary solvent is much greater than that in the main solvent. Adding a certain amount of secondary solvent can improve the dispersibility of the self-assembled small molecules and make the SAMs deposited more compactly and orderly.

[0027] (3) In the present invention, an aqueous solution containing an oxidant is used to treat transition metal oxide nanoparticles, so that the transition metal oxide nanoparticles are smaller and more uniformly induced to produce variable valence transition metal ion surface groups, thereby improving the binding property and binding ability with SAMs.

[0028] (4) The present invention adopts a composite hole transport layer of transition metal oxide-self-assembled small molecule layer. The self-assembled small molecule layer has good adhesion to the relatively dense transition metal oxide layer, which can avoid direct contact between the perovskite and the highly conductive glass substrate to cause power loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a comparison diagram of the current I-voltage V curves of T-1 of Example 1 and C-1 of Comparative Example 1.

[0030] Figure 2 It is a comparison diagram of the current I-voltage V curves of T-4 of Example 4 and C-3 of Comparative Example 3. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further illustrated and described below through specific implementation methods.

[0032] On the one hand, the present invention provides a hole transport layer, which is composed of self-assembled small molecules and thiol-containing organic matter;

[0033] The self-assembling small molecule is selected from one or a combination of two or more of MeO-2PACz, MeO-4PACz, MeOF-4PACz, Me-4PACz, Me-2PACz, MPA-BT-CA, MPA-Ph-CA, MTPA-BA, MC-43, EADR03, Br-2EPT and CbzNaph.

[0034] Self-assembled small molecules are prone to form high-order molecular clusters (such as aggregates such as dimers or polymers), which affects their dispersion performance, resulting in poor bonding and anchoring performance with the bottom transition metal oxide, affecting the hole transport performance. The present invention adds thiol-containing organic matter to the self-assembled small molecules, and the thiol groups of the thiol organic matter are embedded in the self-assembled small molecules to form a mixed layer, rather than forming a passivation layer on the surface of the self-assembled small molecules, which will not affect the crystallization of the overlying perovskite layer, and can hinder the self-assembled small molecules from forming aggregates or high-order molecular clusters, thereby improving the dispersion ability of the self-assembled small molecules, thereby improving the bonding and anchoring performance of the self-assembled small molecule layer and the bottom transition metal oxide.

[0035] In some embodiments, the structure of the thiol-containing organic compound is shown in the following formula (1):

[0036] HSR 1 R 2 (1)

[0037] Among them, R 1 is absent, C1-C4 alkylene or arylene, R 2 Selected from -COOH, -OH, C1-C4 alkyl or -NH 2 For example, the thiol-containing organic compound may be 3-mercaptopropionic acid, thioglycolic acid, mercaptoformic acid, mercaptopropanol, mercaptoethanol, mercaptomethanol, mercaptopropylamine, mercaptoethylamine, mercaptomethylamine, 1-butylmercaptan, 1-propanethiol, thiophenol, 3-methylthiophenol, 4-methylthiophenol, and the like.

[0038] In some embodiments, the weight ratio of the self-assembling small molecule to the thiol-containing organic compound is 0.01-0.1: 1. For example, the weight ratio of the self-assembling small molecule to the thiol-containing organic compound can be any value in 0.01: 1, 0.015: 1, 0.02: 1, 0.025: 1, 0.03: 1, 0.035: 1, 0.04: 1, 0.045: 1, 0.05: 1, 0.055: 1, 0.06: 1, 0.065: 1, 0.07: 1, 0.075: 1, 0.08: 1, 0.085: 1, 0.09: 1, 0.095: 1, 0.1: 1, etc., without any particular limitation.

[0039] On the other hand, the present invention also provides a method for preparing a hole transport layer according to any one of the above embodiments, comprising the following steps:

[0040] Dissolving the self-assembled small molecule layer and the thiol-containing organic matter in a mixed solvent to obtain a precursor solution A;

[0041] The mixed solvent is composed of a main solvent and a secondary solvent. Both the main solvent and the secondary solvent are polar organic solvents. The polarity of the secondary solvent is greater than that of the main solvent. The polarity of the polar organic solvent is evaluated by the dielectric constant. The larger the dielectric constant, the higher the polarity. The dielectric constant of the main solvent at 20° C. is 15-34, and the dielectric constant of the secondary solvent at 20° C. is not less than 36.

[0042] The precursor solution A is deposited on the surface of the transition metal oxide layer and annealed to obtain the hole transport layer. The deposition method can be spin coating, chemical deposition, spray coating, etc., without special restrictions. The annealing temperature can be 50-200° C., and the annealing time can be 1-10 minutes.

[0043] The self-assembled small molecules generally contain a (9H-carbazole-9-yl)phosphonic acid structure or a derivative structure or a similar structure thereof, have strong amphiphilicity, cannot be well dissolved by a single solvent, and are prone to form high-order molecular clusters or aggregates in the solution. The present invention finds that a mixed solvent consisting of a main solvent and a secondary solvent with different polarities is used to dissolve the self-assembled small molecule layer and the thiol-containing organic matter, the main solvent and the secondary solvent are both high-polarity organic solvents, and the polarity of the secondary solvent is higher than that of the main solvent, which can better dissolve the self-assembled small molecules and prevent them from forming high-order molecular clusters or aggregates, thereby improving the bonding and anchoring performance of the formed self-assembled small molecule layer and the bottom transition metal oxide.

[0044] In some embodiments, the weight ratio of the main solvent to the secondary solvent is 9:1-49:1. If the weight ratio of the secondary solvent is too low or too high, it is not conducive to improving the aggregation of self-assembled small molecules or forming high-order molecular clusters. For example, the weight ratio of the main solvent to the secondary solvent can be any value in 9:1, 10:1, 12:1, 13:1, 15:1, 16:1, 18:1, 20:1, 22:1, 24:1, 25:1, 27:1, 30:1, 32:1, 35:1, 37:1, 40:1, 42:1, 45:1, 47:1, 49:1, etc., without special restrictions.

[0045] More preferably, the main solvent is selected from alcohol solvents, especially C1-C4 alkyl alcohols, such as methanol, ethanol, isopropanol IPA, etc.

[0046] More preferably, the secondary solvent is selected from one or a combination of two or more of DMSO, DMF, DMAc, acetonitrile and NMP.

[0047] In some embodiments, the content of the thiol-containing organic matter in the precursor solution is 1-10wt%. For example, the content of the thiol-containing organic matter in the precursor solution can be any value of 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 9.5wt%, 10wt%, etc., without special restrictions.

[0048] On the other hand, the present invention also proposes an inverse perovskite photovoltaic cell, which includes at least a conductive substrate layer, a composite hole transport layer, a perovskite layer, a passivation layer, an electron transport layer and a back electrode from bottom to top; preferably, a hole blocking layer can also be arranged between the electron transport layer and the back electrode.

[0049] The composite hole transport layer comprises a hole transport layer described in any of the above embodiments or a hole transport layer prepared by the method for preparing a hole transport layer described in any of the above embodiments and a transition metal oxide layer, and the hole transport layer is located above the transition metal oxide layer. That is, in the above composite hole transport layer, the transition metal oxide layer is located between the hole transport layer and the conductive substrate layer. In the present invention, there is no particular limitation on the thickness of the hole transport layer and the transition metal oxide layer, for example, the thickness of the hole transport layer can be 1-20 nm, and the thickness of the transition metal oxide layer can be 5-30 nm.

[0050] In some embodiments, the transition metal oxide layer is composed of transition metal oxide nanoparticles oxidized by an oxidant. After the transition metal oxide nanoparticles are oxidized by an oxidant, the transition metal oxide nanoparticles become smaller, and can more evenly induce the generation of variable valence transition metal ion surface groups, and improve the binding performance with the self-assembled small molecule layer, thereby improving the hole transport performance. Therefore, in the present invention, the binding force or bonding anchoring performance between the self-assembled small molecule layer and the transition metal oxide layer is improved by the following two methods, thereby improving the quality of the interface between the trans-perovskite and the buried bottom, and improving the photoelectric conversion efficiency and operation stability of the trans-perovskite solar cell; method (1), adding thiol-containing organic matter to the self-assembled small molecule layer, hindering the aggregation of the self-assembled small molecules or forming high-order molecular clusters, is conducive to the dispersion of the self-assembled small molecules; method (2), the transition metal oxide nanoparticles used in the transition metal oxide layer are oxidized by an oxidant, and the particles are finer, and can evenly induce the generation of variable valence transition metal ion surface groups.

[0051] The transition metal oxide nanoparticles include at least one of nickel oxide, tin oxide, molybdenum oxide, manganese oxide, copper oxide, iron oxide, zinc oxide and cobalt oxide, preferably nickel oxide nanoparticles, wherein the nickel oxide is in the form of NiO xIndicates that it contains NiO, Ni 2 O 3 and NiO 2 The average particle size of the transition metal oxide nanoparticles may be 10-50 nm.

[0052] Specifically, the specific method for preparing a transition metal oxide layer composed of transition metal oxide nanoparticles oxidized by an oxidant can be as follows: the transition metal oxide nanoparticles are dispersed in a solution containing an oxidant to obtain a precursor solution B, and the precursor solution B is deposited on a conductive substrate layer by spin coating, spraying, etc. and annealed to obtain a transition metal oxide layer.

[0053] In the above method, the solution containing the oxidant is not particularly limited, and can be a hydrogen peroxide solution, a peracetic acid solution, a peroxyformic acid solution, a dicumyl peroxide solution, a benzoyl peroxide solution, a methyl ethyl ketone peroxide solution, a cyclohexanone peroxide solution, a tert-butyl alcohol peroxide solution, a tert-butyl perbenzoate peroxide solution, etc., preferably a hydrogen peroxide solution. The concentration of the solution containing the oxidant can be 0.1-0.5wt%. Too high or too low a concentration is not suitable. The transition metal oxide nanoparticles are NiO x For example, the oxidant concentration is too low to effectively reduce NiO x Agglomeration of nanoparticles. Too high an oxidant concentration will produce too much Ni 3+ , which damages the contact quality between the nickel oxide layer and the hole transport layer. The annealing temperature can be 50-200°C, and the annealing time can be 1-10 minutes. The concentration of transition metal oxide nanoparticles in the precursor solution B can be 10-50 mg / ml.

[0054] In the present invention, the material of the conductive substrate layer is not particularly limited, and for example, it can be ITO glass. Before use, the conductive substrate layer must be cleaned and / or the organic matter on the surface must be removed; the material of the perovskite layer is not particularly limited, and for example, it can be (Rb a Cs b MA c FA d )Pb(I x Br y Cl z ) 3 , where MA is methylamine (chemical formula CH 3 NH 2 ), FA is formamidine (chemical formula HC(NH 2 ) 2), a, b, c, d, x, y, z are all any values ​​between 0 and 1, and a+b+c+d=1, x+y+z=1; the passivation layer can effectively improve the electron migration ability and the photoelectric conversion efficiency of the perovskite solar cell. The passivation layer material is not particularly limited. For example, it can be phenylethylamine iodate (PEAI), phenylethylamine bromide (PEABr), phenylethylamine hydrochloride (PEACl), piperazine derivatives, guanidine salts, n-octylammonium iodide, isobutylammonium hydrobromide, 3-aminomethylpyridine, etc.; the electron transport layer is not particularly limited, and can be PCBM, C 60 , BCP, etc.; there is no special restriction on the material of the back electrode, and it can be a metal material or a metal alloy material such as Au, Ag, Cu, Mo, Ni, etc.

[0055] The technical solution of the present invention is further described and illustrated according to various embodiments below.

[0056] Example 1

[0057] (1) Cleaning of the conductive substrate: Place a 2 cm × 2 cm ITO glass in a glass holder, use acetone ultrasonic cleaning for 15 min, then place in a 60°C oven for drying, then place in a UV ozone cleaning agent for 20 minutes, and then take out for use.

[0058] (2) Preparation of hole transport layer 1 precursor solution B: Add 25 μL of 40% hydrogen peroxide solution to 5 mL of water to prepare a solution with a concentration of 2 wt‰, and then add 75 mg of nano-NiO with an average particle size of 20 nm to the solution. x After 15 minutes of ultrasound treatment, the precursor solution B of the hole transport layer 1 was obtained.

[0059] (3) Preparation of hole transport layer 1: Place the ITO glass on a spin coater, place the ITO glass in the center of the base of the spin coater, click the vacuum adsorption button, blow the ITO surface with a nitrogen gun, use a pipette to transfer 200 μL of the above precursor solution B and drop it on the surface of the ITO glass before starting spin coating. The spin coating process is 2000 rpm × 30s, and the acceleration is 1000 rpm / s. After the spin coating is completed, remove the ITO glass and anneal it at 200 ° C for 10 minutes to obtain the intermediate layer 1, which is transferred to the sample box and placed in the glove box.

[0060] (4) Preparation of hole transport layer 2 precursor solution A: 100 μL of 3-mercaptopropionic acid was added to 5 mL of a mixed solvent of IPA / DMF with a weight ratio of 9:1, and then 2.5 mg of Meo-2PACz was added. The mixture was completely dissolved by ultrasonication for 15 min to obtain a hole transport layer 2 precursor solution A.

[0061] (5) Preparation of hole transport layer 2: Place the above-mentioned intermediate layer 1 in the center of the spin coater base, click the vacuum adsorption button, use a pipette to take 150 μL of precursor solution A, drop it on the surface of the hole transport layer 1, let it stand for 5 seconds, and then click to start spin coating. The spin coating process is 3000 rpm×30s, and the acceleration is 3000 rpm / s. After the spin coating is completed, remove the glass and anneal it at 100°C for 10 minutes to obtain the intermediate layer 2, which is then transferred to the sample box for storage.

[0062] (6) Preparation of perovskite layer: The perovskite formula is Cs 0.05 R 0.05 MA 0.05 FA 0.85 Pb(I 0.95 Br 0.05 ) 3 , the concentration is 1.5M. After configuration, use a 0.22μm filter head to filter and remove insoluble matter in the perovskite precursor solution. Place the intermediate layer 2 in the center of the spin coater base, and click the vacuum adsorption button to start spin coating. Use a pipette to take 80μL of perovskite precursor solution, drop it on the sample surface, and click to start spin coating. The spin coating process is 1000rpm×10s and 3000rpm×40s, and the acceleration is 3000rpm / s. Add the anti-solvent chlorobenzene between 32-35s. After the spin coating is completed, remove the sample and anneal it at 100℃ for 10min to obtain the intermediate layer 3, which is transferred to the sample box for storage.

[0063] (7) Preparation of passivation layer: Dissolve 1 mg PEAI in 1 mL IPA to obtain a passivation layer precursor solution. Place the above intermediate layer 3 in the center of the spin coater base and click the vacuum adsorption button to start spin coating. The spin coating process is 4000 rpm × 40 s, with an acceleration of 4000 rpm / s. After 10 s, use a pipette to drop 70 μL of the passivation layer precursor solution at the center to obtain the intermediate layer 4.

[0064] (8) Preparation of electron transport layer: 20 mg of PCBM was dissolved in 1 mL of chlorobenzene to obtain an electron transport layer precursor solution. The PCBM solution was filtered and the intermediate layer 4 was placed in the center of the spin coater base. The vacuum adsorption button was clicked and 120 μL of PCBM solution was taken with a pipette and dropped on the sample surface. The spin coating process was 2000 rpm × 30 s and the acceleration was 2000 rpm / s to obtain the intermediate layer 5.

[0065] (9) Preparation of hole blocking layer: 0.5 mg of BCP was dissolved in 1 mL of IPA to obtain a hole blocking layer precursor solution. The intermediate layer 5 was placed in the center of the spin coater base, and the vacuum adsorption button was clicked to start spin coating. The spin coating process was 5000 rpm × 40 s, with an acceleration of 2500 rpm / s. After 10 s, 70 μL of the hole blocking layer precursor solution was dripped into the center with a pipette to obtain the intermediate layer 6, which was then placed in a sample box for storage.

[0066] (10) Evaporation of back electrode: The intermediate layer 6 is transferred to the evaporation glove box, and the perovskite films on both sides are scraped off with a scraper to expose the bottom electrode. After processing, the sample is placed on the mask in the correct direction, and the mask is placed in the evaporation box. The evaporation speed is After evaporation of 100 nm, an inverse perovskite photovoltaic cell was obtained, which was marked as T-1.

[0067] Example 2

[0068] The difference between this embodiment and embodiment 1 is that when the precursor solution B is prepared in embodiment 1, the nano NiO with an average particle size of 20 nm is x The amount of the catalyst was adjusted from 75 mg to 150 mg. The remaining steps remained unchanged to obtain an inverse perovskite photovoltaic cell, which was recorded as T-2.

[0069] Example 3

[0070] The difference between this embodiment and embodiment 1 is that in embodiment 1, the amount of 3-mercaptopropionic acid added is adjusted so that the concentration of 3-mercaptopropionic acid in the precursor solution A is adjusted to 1 wt %. The remaining steps remain unchanged to obtain a trans-perovskite photovoltaic cell, which is recorded as T-3.

[0071] Example 4

[0072] The difference between this embodiment and embodiment 1 is that in embodiment 1, the amount of 3-mercaptopropionic acid added is adjusted so that the concentration of 3-mercaptopropionic acid in the precursor solution A is adjusted to 10 wt %. The remaining steps remain unchanged to obtain a trans-perovskite photovoltaic cell, which is recorded as T-4.

[0073] Comparative Example 1

[0074] The difference between this comparative example and Example 1 is that the hole transport layer 1 is omitted in the inverse perovskite photovoltaic cell in Example 1. The remaining steps remain unchanged to obtain an inverse perovskite photovoltaic cell, which is recorded as C-1.

[0075] Comparative Example 2

[0076] The difference between this comparative example and Example 1 is that the hole transport layer 2 is omitted in the inverse perovskite photovoltaic cell in Example 1. The remaining steps remain unchanged to obtain an inverse perovskite photovoltaic cell, which is recorded as C-2.

[0077] Comparative Example 3

[0078] The difference between this comparative example and Example 1 is that 3-mercaptopropionic acid is not added to the precursor solution A in Example 1. The remaining steps remain unchanged, and a perovskite photovoltaic cell is obtained, denoted as C-3.

[0079] Example 5

[0080] The difference between this example and Example 1 is that in Example 1, the weight ratio of IPA / DMF in the precursor solution A of the hole transport layer 2 is adjusted from 9:1 to 19:1. The remaining steps remain unchanged, and a perovskite photovoltaic cell is obtained, denoted as T-5.

[0081] Example 6

[0082] The difference between this example and Example 1 is that in Example 1, the weight ratio of IPA / DMF in the precursor solution A of the hole transport layer 2 is adjusted from 9:1 to 49:1. The remaining steps remain unchanged, and a perovskite photovoltaic cell is obtained, denoted as T-6.

[0083] Comparative Example 4

[0084] The difference between this comparative example and Example 1 is that in Example 1, the IPA / DMF in the precursor solution A of the hole transport layer 2 is adjusted to equal weight of IPA. The remaining steps remain unchanged, and a perovskite photovoltaic cell is obtained, denoted as C-4.

[0085] Comparative Example 5

[0086] The difference between this comparative example and Example 1 is that in Example 1, the IPA / DMF in the precursor solution A of the hole transport layer 2 is adjusted to equal weight of DMF. The remaining steps remain unchanged, and a perovskite photovoltaic cell is obtained, denoted as C-5.

[0087] Comparative Example 6

[0088] The difference between this comparative example and Example 1 is that in Example 1, the weight ratio of IPA / DMF in the precursor solution A of the hole transport layer 2 is adjusted from 9:1 to 5:1. The remaining steps remain unchanged, and a perovskite photovoltaic cell is obtained, denoted as C-6.

[0089] Example 7

[0090] The difference between this example and Example 1 is that in Example 1, when preparing the precursor solution B of the hole transport layer 1, the concentration of the hydrogen peroxide solution is adjusted to 1 wt‰. The remaining steps remain unchanged, and a perovskite photovoltaic cell is obtained, denoted as T-7.

[0091] Example 8

[0092] The difference between this embodiment and embodiment 1 is that in embodiment 1, when preparing the precursor solution B of the hole transport layer 1, the concentration of the hydrogen peroxide solution is adjusted to 5 wt‰. The remaining steps remain unchanged to obtain an inverse perovskite photovoltaic cell, which is recorded as T-8.

[0093] Comparative Example 7

[0094] The difference between this comparative example and Example 1 is that in Example 1, no hydrogen peroxide solution is added when preparing the precursor solution B of the hole transport layer 1. The remaining steps remain unchanged to obtain an inverse perovskite photovoltaic cell, which is recorded as C-7.

[0095] Comparative Example 8

[0096] The difference between this comparative example and Example 1 is that in Example 1, when preparing the precursor solution B of the hole transport layer 1, the concentration of the hydrogen peroxide solution is adjusted to 8 wt ‰. The remaining steps remain unchanged to obtain an inverse perovskite photovoltaic cell, which is recorded as C-8.

[0097] Example 9

[0098] The difference between this embodiment and embodiment 1 is that in embodiment 1, when preparing the body solution A, the mixed solvent is adjusted to be composed of IPA / DMAc in an equal volume at a weight ratio of 19:1. The remaining steps remain unchanged to obtain an inverse perovskite photovoltaic cell, which is recorded as T-9.

[0099] Example 10

[0100] The difference between this embodiment and embodiment 1 is that in embodiment 1, when preparing the body solution A, the mixed solvent is adjusted to be composed of anhydrous ethanol / DMSO in an equal volume at a weight ratio of 19:1. The remaining steps remain unchanged to obtain a trans-perovskite photovoltaic cell, which is recorded as T-10.

[0101] The performance test results of the inverse perovskite photovoltaic cells of Examples 1-10 and Comparative Examples 1-8 are shown in Table 1 below, where V oc is the open circuit voltage, FF is the fill factor, J sc is the short-circuit current, PCE is the photoelectric conversion efficiency, Fwd is the forward scan, and Rev is the reverse scan.

[0102] The current I-voltage V curves of T-1 of Example 1 and C-1 of Comparative Example 1 are shown in the attached figure. Figure 1 As shown, the current I-voltage V curves of T-4 of Example 4 and C-3 of Comparative Example 3 are compared as shown in the attached figure. Figure 2 shown.

[0103] Table 1

[0104]

[0105]

[0106] Therefore, the above examples and comparative examples confirm that the inverse perovskite photovoltaic cell adopts NiO x / Meo-2PACz composite hole transport layer, in which NiO x After oxidation treatment, 3-mercaptopropionic acid is added to Meo-2PACz and dissolved in a mixed solvent, which can effectively improve the buried performance of the device and make the photoelectric conversion efficiency reach more than 22%.

[0107] As described above, the basic principles, main features and advantages of the present invention are shown and described. Those skilled in the art should understand that the present invention is not limited by the above embodiments, which are only preferred embodiments of the present invention and cannot be used to limit the scope of the present invention. That is, equivalent changes and modifications made according to the scope of the present invention and the contents of the specification should still be within the scope of the present invention. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A hole transport layer, characterized in that: The hole transport layer is composed of self-assembled small molecules and thiol-containing organic matter; The self-assembling small molecule is selected from one or a combination of two or more of MeO-2PACz, MeO-4PACz, MeOF-4PACz, Me-4PACz, Me-2PACz, MPA-BT-CA, MPA-Ph-CA, MTPA-BA, MC-43, EADR03, Br-2EPT and CbzNaph.

2. The hole transport layer according to claim 1, characterized in that The structure of the mercapto-containing organic compound is shown in the following formula (1): HSR 1 R 2 (1) Among them, R 1 is absent, C1-C4 alkylene or arylene, R 2 Selected from -COOH, -OH, C1-C4 alkyl or -NH2.

3. The hole transport layer according to claim 1, characterized in that The weight ratio of the self-assembling small molecules to the thiol-containing organic matter is 0.01-0.1:

1.

4. A method for preparing a hole transport layer according to any one of claims 1 to 3, characterized in that: The following steps are involved: Dissolving the self-assembled small molecule layer and the thiol-containing organic compound in a mixed solvent to obtain a precursor solution A; The mixed solvent consists of a main solvent and a secondary solvent, and the polarity of the secondary solvent is greater than that of the main solvent; The precursor solution A is deposited on the surface of the transition metal oxide layer and annealed to obtain the hole transport layer.

5. The method for preparing a hole transport layer according to claim 4, characterized in that: The weight ratio of the main solvent to the secondary solvent is 9:1-49:

1.

6. The method for preparing a hole transport layer according to claim 5, characterized in that: The main solvent is selected from alcohol solvents.

7. The method for preparing a hole transport layer according to claim 5, characterized in that: The secondary solvent is selected from one or a combination of two or more of DMSO, DMF, DMAc, acetonitrile and NMP.

8. The method for preparing a hole transport layer according to claim 4, characterized in that: The content of the mercapto-containing organic compound in the precursor solution is 1-10 wt %.

9. An inverse perovskite photovoltaic cell, characterized in that: From bottom to top, it includes at least a conductive substrate layer, a composite hole transport layer, a perovskite layer, a passivation layer, an electron transport layer and a back electrode; The composite hole transport layer comprises a hole transport layer according to any one of claims 1 to 3 or a hole transport layer prepared by the method for preparing a hole transport layer according to any one of claims 4 to 8 and a transition metal oxide layer, wherein the hole transport layer is located above the transition metal oxide layer.

10. The inverse perovskite photovoltaic cell according to claim 9, characterized in that: The transition metal oxide layer is composed of transition metal oxide nanoparticles oxidized by an oxidant.

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