Process for manufacturing a multi-cation perovskite layer

Abstract

A process for manufacturing a multi-cation perovskite layer (100) comprising: a) supplying a substrate (1) having a deposition face (2), b) deposition of a precursor solution comprising precursors including CsX, FAY, PbZ2, with X, Y and Z = I, Br, and an additive FACl, the molar ratio of cesium to lead being between about 4% and 22%, the molar ratio of FACl to lead being between 0.1% and 5%, and the perovskite layer (100) having a molecular formula of the form CsxFA(1-x+w)Pb(IyBr(1-y))3 with x between 0.04 and 0.22, y between 0 and 1 and w between 0.001 and 0.05, c) scanning the wet film (5) with an inert gas to crystallize the layer perovskite (100), and heat treatment such that the deposition face (2) has a temperature ranging from approximately 25°C to at least 80°C during step b). Figure for the abstract: Figure 2

Description

Title of the invention: Method for manufacturing a multi-cation perovskite layer

[0001] The present invention relates to the field of perovskite-type material layers for applications in the microelectronic and optoelectronic fields. More particularly, the present invention relates to a method for manufacturing a photoactive halogenated hybrid perovskite layer, and in particular a multi-cation perovskite layer, for use in photovoltaic devices, LEDs, photodetectors, microbatteries, or other devices utilizing their semiconducting properties.

[0002] Halogenated hybrid perovskites are promising materials, and much development is underway to improve their quality and stability, particularly for the manufacture of solar cells. Indeed, lead halide perovskite hybrid organic-inorganic solar cells have shown a remarkable increase in energy conversion efficiency over a relatively short period (10 years). However, the challenges of this technology are 1) scaling up the deposition processes of the different layers, especially the perovskite layer, 2) the stability of photovoltaic devices under real-world conditions, and 3) the presence of lead (Pb) in the absorbing layer of these devices. This invention addresses the first point.Indeed, most of the manufacturing processes developed to date for depositing perovskite materials with physical and optoelectronic properties leading to high photovoltaic performance (>20%) are carried out on a laboratory scale, on small surfaces. Therefore, there remains a need for the design and optimization of processes enabling the industrial-scale production of high-quality perovskite layers at a reasonable cost and without degradation of their properties.

[0003] When a spin coating deposition method is used, the precursors of the target perovskite layer are dissolved and spread onto a rotating substrate. Spraying an anti-solvent onto the rotating substrate initiates perovskite nucleation, thus producing high-quality optoelectronic coatings. However, when this deposition method is used over a large area, a non-homogeneous wet film is produced due to the inhomogeneity of the centrifugal effect. Other deposition methods exist, such as blade coating, slot die coating, or inkjet printing, etc. Although these methods are better suited to the industrial-scale deposition of a precursor solution, a major problem lies in the difficulty of achieving crystallization of the A perovskite film spread on the substrate, regardless of the film formation method. The anti-solvent method, which relies on centrifugal force, is poorly suited to large substrates. Furthermore, this method typically uses a toxic or hazardous solvent (chlorobenzene or toluene) with operators working in glove boxes, an environment unsuitable for industrial-scale use.

[0004] Finally, when implemented in air, which is desirable for an industrial-scale application, the resulting devices may exhibit limited performance, particularly in terms of Voc.

[0005] One of the aims of the present invention is to overcome at least one of these drawbacks. To this end, the invention proposes a method for manufacturing a multi-cation perovskite layer, with a view to forming a photoactive layer, the method comprising the steps of: - a) provision of a substrate having a deposition face, - b) deposition of a precursor solution comprising at least one solvent and perovskite precursors so as to form a wet film on the deposit face, the precursors comprising at least CsX, FAY, PbZ2, with X, Y and Z = I, Br, and an additive of FAQ, the amounts being determined such that the molar ratio of cesium to lead is between about 4% and 22%, preferably between 13% and 20%, that the molar ratio of FAQ to lead is between 0.1% and 5%, in particular between 0.1% and 2%, and that the perovskite layer has an empirical formula of the form CsxFA (i_x+w)Pb(IyBr(i_y))3 with x between 0.04 and 0.22, including between 0 and 1, and w between 0.001 and 0.05, and - c) sweeping an exposed surface of the wet film with a stream of dry air or inert gas at a speed greater than or equal to 120 m / s so as to crystallize the multi-cation perovskite layer,

[0006] the process further comprising applying a heat treatment to the substrate so that the deposition face has a temperature ranging from about 25°C to at least 80°C during step b).

[0007] Contrary to expectations, this combination of parameters relating to the heat treatment applied to the substrate, the composition of the precursor solution used, the presence of a chlorinated additive, the deposition method, and the crystallization method, particularly the gas flow velocity associated with the composition of the precursor solution, makes it possible to obtain a perovskite layer of very high crystalline quality over its entire surface, as will be seen below. Furthermore, the manufacture of photovoltaic cells using the photoactive perovskite layer thus produced gives efficiency results similar to those obtained with a layer deposited by spin coating'. Furthermore, the presence of the FAQ additive makes it possible to limit or even eliminate the appearance of the Pbl2 peak (XRD analyses) following prolonged heat treatment, as classically observed, as will be seen in detail in the rest of the description.

[0008] In this document, the term 'perovskite layer' means a polycrystalline perovskite layer (alpha phase), as opposed in particular to an amorphous layer or a yellow, non-absorbing delta phase in the desired range. In this document, the term FA is well known to those skilled in the art in the field of perovskites and designates Formamidinium HC(NH2)2+.

[0009] The perovskite layer obtained at the end of the process is not perfectly stoichiometric. It has already been reported that perovskite exists in a "sub-" or "super-stoichiometric" form, depending on the method of obtaining it, without necessarily affecting its crystalline quality or its absorption properties (see 'Qualitative Assessment of the Use of Excess Lead Iodide in Lead Halide Perovskite Solar Cells' by Bart Roose et al. in J. Phys. Chem. Lett. 2020, 11, 16, 6505-6512 or 'Fractional deviations in precursor stoichiometry dictate the properties, performance and stability of perovskite photovoltaic devices' by Paul Fassl et al. in Energy Environ. Sci., 2018, 11, 3380-3391).

[0010] However, as already reported on several occasions, notably by Qi Jiang et al. 'Surface passivation of perovskite film for efficient solar cells' in Nature Photonics Volume 13, pages 460-466 (2019), and by Jason J. Yoo et al. 'An interface stabilized perovskite solar cell with high stabilized efficiency and low voltage loss' in Energy & Environmental Science Issue 7, 2019, when using PbCl2 to form MA-based perovskites (and initially MAPbI3-based perovskites), it was observed in the context of the invention that the chlorine in the FAQ additive was not, or only very slightly, integrated into the crystal lattice of the perovskite layer formed at the end of the process. Some hypotheses suggest possible evaporation during the crystallization heat treatment to explain its absence in the resulting perovskite.

[0011] Furthermore, the deposition technique used in the process of the invention can advantageously be used on an industrial scale; deposition on a 5 x 5 cm² surface has, in fact, given good results. The powders of the precursor materials used are not unstable and are therefore compatible with an industrial solution. Crystallization according to the invention does not require the application of significant thermal annealing after step c) of applying gas flow, which reduces manufacturing costs and potential damage to the crystalline structure. Nevertheless, if such thermal annealing were to be applied, the presence of the additive FAQ makes it possible to limit the appearance of crystallized Pbl2 domains, which are potentially detrimental to the yields of the perovskite layer obtained, as will be seen in detail. in the rest of the description.

[0012] Furthermore, the absorption spectrum of hybrid perovskites formed by the process of the present invention, having a general formula of the type CsxFA(i_x+w)Pb(IyBr(i_y))3 comprising lead, halides and two cations is very interesting and can be modified in particular by adjusting the rate of halides in the composition.

[0013] The expression 'dry air' also means compressed air (8 bar) with a dew point below -20°C, and preferably a dew point below -40°C.

[0014] According to one arrangement, the exposed surface of the wet film corresponds to the entire exposed face of the wet film so that the entire wet film is swept by the flow of dry air or inert gas.

[0015] According to one possibility, the application of a heat treatment to the substrate is carried out so that the deposition face has a temperature ranging from 30°C to 70°C, and preferably from approximately 40°C to 60°C. It is indeed advantageous to limit the heat treatment applied to the substrate for economic reasons. If the solvent in the wet film evaporates less readily at 40°C than at 80°C, this can be compensated for by increasing the gas flow velocity.

[0016] According to one provision, said heat treatment is applied to the substrate so that the deposition face has a temperature ranging from about 25°C to 80°C during step b) and step c).

[0017] According to one embodiment, the precursors of the perovskite layer are chosen from a combination of CsX, FAY, and PbZ2, with X, Y, and Z = I, Br, and additive FAQ. In other words, in this embodiment, the precursor solution is devoid of any precursors or additives other than those mentioned in the list above.

[0018] According to another possibility, the precursor solution consists of precursors selected from CsX, FAY, PbZ2, and any combination thereof, with X, Y, and Z selected from I and Br, the additive FAQ, and at least one solvent. In other words, the precursor solution is free of any element other than at least one solvent, the precursors CsX, FAX, PbZ2, and any combination thereof, with X selected from I and Br, and the additive FAQ. The composition of the precursor solution is thus free of any other additive or MA+ (methylammonium) cation, the presence of which could alter the stability of the resulting layer.

[0019] According to one possibility, at least one solvent is chosen from DMF and / or DMSO.

[0020] The choice of the composition of at least one solvent is an important element to facilitate the preparation of the precursor solution by dissolving the precursor elements of the perovskite material and the additive FAQ, and the crystallization which involves the evaporation of said at least one solvent.

[0021] According to one provision, the precursor solution comprises a molar concentration of lead between 0.5 M and 1.7 M, in particular between 0.6 and 1.5 M and for example between 1 M and 1.3 M.

[0022] Preferably, the only thermal budget applied during the manufacturing process is provided by the heat treatment applied to the substrate so that the deposition face has a temperature ranging from approximately 25°C to 80°C during steps b) and c). In practice, said heat treatment is applied before the deposition step b) so that the deposition face has the desired temperature at the time of starting the deposition and it is stopped at the end of step c).

[0023] According to another possibility, step c) of applying the inert gas or dry air stream is followed, after obtaining the crystalline perovskite layer, by step d) of applying thermal annealing at a temperature between 70°C and 100°C. The duration of this thermal annealing is between approximately 5 and 60 minutes, and in a variation between 5 and 30 minutes. This option may be useful for certain targeted perovskite molecular formulas; depending on the values ​​of x, y, and w of the molecular formula CsxFA(i_x+w)Pb(IyBr(i_y))3, it may be desirable to eliminate any minute trace of precursor materials or residual solvent that would not be removed in step c). This possible step d) differs from the thermal annealing known in the prior art, particularly in its duration.

[0024] However, prolonged annealing can be applied after step c) without the appearance of Pbl2 (signal visible by XRD), as is generally observed in the absence of FAQ. Annealing at 100°C for a duration of 60 min is particularly feasible under an inert atmosphere. The addition of the FAQ additive can increase the annealing time range without degrading the perovskite layer.

[0025] Preferably, step c) of scanning by a flow of inert gas or dry air is carried out by a relative displacement of the substrate comprising the wet film and a projection nozzle, such as a projection nozzle of a gas knife, the projection nozzle being arranged so that the length L of the path of the flow of inert gas or dry air between the outlet of the projection nozzle and the exposed surface of the wet film is between about 3.1 millimeters and 6 millimeters, and preferably between about 3.1 millimeters and 4 millimeters.

[0026] More specifically, the outlet of the projection nozzle is delimited by a lower lip and an upper lip spaced apart to form a projection space for the inert gas or dry air flow in the overall shape of a blade, the lower lip defining a low point B and the upper lip defining a high point H. It is understood in this document that the length L of the path of the inert gas or dry air flow between the outlet of the projection nozzle and the exposed surface of the wet film is measured between the high point H and the exposed surface of the wet film. As we have seen, as will be seen below and with reference to the attached figures 4 and 5, said length L depends on the angle a formed between the wet film and the direction of the flow of inert gas or dry air.

[0027] It is understood that the velocity of the inert gas or dry air flow indicated in this document is measured and / or calculated at the outlet of a projection nozzle of a device for projecting said flow. The flow velocity is a function of the gas flow rate and the surface area of ​​the opening at the outlet of the projection nozzle.

[0028] In this document, the expression 'gas knife' or 'air knife' corresponds to the expression well known to those skilled in the art under the Anglo-Saxon names respectively 'gas knife' and 'air knife'.

[0029] Preferably, the relative movement speed between the wet film and the projection nozzle during step c) is between 1 and 50 mm / s and preferably between 5 and 30 mm / s.

[0030] According to one arrangement, the deformed angle between the inert gas or dry air flow and the wet film is between 90° and 45°.

[0031] Advantageously, step b) of depositing the precursor solution is carried out by coating via a flat die or via a blade coating, so as to obtain a wet film of constant thickness and homogeneous concentration. These deposition techniques are indeed used on the large deposition areas required in an industrial solution.

[0032] In this document, the expression 'coating via a flat die' corresponds to the technique well known to those skilled in the art under the Anglo-Saxon name 'slot die coating'. Similarly, blade coating corresponds to the technique well known to those skilled in the art under the Anglo-Saxon name 'blade coating', sometimes also called 'blade coating'.

[0033] According to one arrangement, step b) of deposition consists of depositing the precursor solution by a deposition head of the slot die coating device onto the deposition face, with a flow rate of between 80 and 125 microlitre / min for a molar concentration of lead in the precursor solution of between 1 M and 1.3 M.

[0034] According to one possibility, step b) of depositing the precursor solution is carried out so as to obtain a constant wet film thickness, between 2 and 16 micrometers preferably between 2.5 and 8 micrometers and even more preferably between 3 and 5 micrometers.

[0035] These ranges of wet film thicknesses ensure that it is possible in step c) to obtain crystallization of the perovskite layer with good quality and yield. These thicknesses naturally depend on the concentration of the precursor solution to obtain a crystalline perovskite layer with a thickness in the range of approximately 350–600 nm.

[0036] In order to reduce the thermal budget applied to steps b) and c) while maintaining With good crystallization of the perovskite layer, it is possible to limit the scanning speed of the film by the projection nozzle.

[0037] Another lever consists of modifying the concentration in the precursor solution, within the ranges indicated above.

[0038] It is also possible to position oneself in a lower part of the range of the length L of the trajectory of the gas flow. In practice, the projection nozzle is brought closer to the exposed surface of the wet film, with a vertical distance D between 100 and 400 micrometers for example.

[0039] Another option is to choose a speed of the inert gas or dry air flow from among the fastest of the possibilities offered by the projection nozzle, for example from 135 m / s to 250 m / s.

[0040] According to other features, the manufacturing process of the invention comprises one or more of the following optional features considered alone or in combination: - The relative speed between the deposition face and the deposition head (in the case of slot die coating) of the precursor solution or of the spreading blade (in the case of blade coating) is between approximately 1 and 100 mm / s and preferably between 15 and 45 mm / s and even more preferably between approximately 20 and 30 mm / s. - The application of the inert gas flow or dry air according to step c) is carried out on the exposed surface of the wet film before the end of the deposition of the precursor solution according to step b). - The application of the inert gas flow or dry air according to step c) is carried out on the exposed surface of the wet film after the completion of the deposition of the precursor solution according to step b). - The relative velocity between the deposition head or the spreading blade of the precursor solution and the deposition face is similar to the relative velocity between the wet film and the projection nozzle of the inert gas flow or dry air. - The relative speed between the deposition head or spreading blade and the deposition face is greater than the relative speed between the wet film and the projection nozzle of the inert gas flow or dry air. - The relative speed between the deposition head or spreading blade and the deposition face is less than the relative speed between the wet film and the projection nozzle of the inert gas flow or dry air. - The movement between the deposition face and the deposition head (or spreading blade) and the movement between the exposed surface of the wet film and the projection nozzle consists of translational movement, in the longitudinal extension direction of the deposition face. - The flow of dry air or inert gas is distributed from a gas source compressed. It is projected onto the exposed surface of the wet film at a temperature of approximately 15°C to 25°C without an intermediate heating step. - The flow of dry air or inert gas has a velocity between 120 m / s and 250 m / s during step c). - The vertical distance D between the exposed surface of the wet film and point B of the projection nozzle outlet is between 100 micrometers and 1 mm and preferably between 200 and 400 micrometers. - The projection nozzle is devoid of a flat so that M = 0 and the low point B and the high point H are at the same vertical distance D from the exposed surface of the wet film. - The heat treatment of the substrate is carried out by placing the substrate on a dedicated heating platform, so that the support is heated through a face opposite to the wet film deposition face. - The heat treatment is stopped at the end of step b). - The precursor solution deposition head is positioned at a measured distance directly above the deposition face, between 25 and 500 micrometers and preferably between about 80 and 125 micrometers, and even more preferably about 100 micrometers. - The distance between the spreading blade during blade coating and the deposition face is between 25 and 200 micrometers and in particular between 50 and 100 micrometers. - Steps a) to c) and the heat treatment are carried out in a cleanroom enclosure with a temperature between 20 and 35°C. - Steps a) to c) and the heat treatment are carried out in a cleanroom enclosure with a relative humidity level between 8 and 38%. - The cleanroom has a temperature of approximately 21°C and a relative humidity of approximately 35%.

[0041] - The perovskite layer obtained in step c) has a thickness of approximately 500 nanometers.

[0042] - The manufacturing process is devoid of a conversion solvent-resistant treatment from wet film to crystalline film.

[0043] - The substrate used for deposition is a wafer-type substrate of a few hundred micrometers, for example in silicon or glass, or a thin and flexible substrate in a rolled form. In the latter case, the substrate is driven by a translational movement leading to its unwinding and movement under the stationary slot die coating or blade coating device, and under the nozzle projecting a flow of inert gas or dry air, also stationary.

[0044] The invention will be more fully understood upon reading the following non-limiting description, made with reference to the figures attached hereto.

[0045] [Fig-1] is a schematic view illustrating steps a) to b) of an embodiment of the process of the invention.

[0046] [Fig.2] is a schematic view illustrating steps b) and c) of the process of the invention.

[0047] [Fig.3] is a schematic view illustrating step c) of the process of the invention.

[0048] [Fig.4] is a schematic view of the outlet of a gas flow projection nozzle according to step c) of the process of the invention.

[0049] [Fig.5] is a schematic view of an inclined projection nozzle according to step c) of the method of the invention.

[0050] [Fig.6] is a schematic view of an architecture of the structure for a NIP type solar cell formed from a layer of perovskite 100 manufactured according to an embodiment of the process of the invention.

[0051] [Fig.7] is a view of an X-ray diffraction (XRD) analysis of the structure for a NIP-type solar cell without additive FAQ.

[0052] [Fig.8] is an XRD view of the structure for a NIP type solar cell comprising a molar ratio of 0.1% of FAQ relative to lead according to an embodiment of the process of the invention.

[0053] [Fig.9] is a view of an XRD analysis of the structure for a NIP type solar cell comprising a molar ratio of 0.5% of FAQ relative to lead according to an embodiment of the process of the invention.

[0054] [Fig. 10] is a view of an XRD analysis of the structure for a PIN-type solar cell without additive FAQ.

[0055] [Fig. 11] is a view of an XRD analysis of the structure for a PIN type solar cell comprising a molar ratio of 0.1% of FAQ relative to lead according to an embodiment of the process of the invention.

[0056] [Fig. 12] is a view of an XRD analysis of the structure for a PIN type solar cell comprising a molar ratio of 0.5% of FAQ relative to lead according to an embodiment of the process of the invention.

[0057] In the following examples, the Pbl2 used is 99.99% pure and comes from TQ Chemicals (Japan), the PbBr2, FAI, Csl, FAQ, DMF and DMSO come from Sigma Aldrich.

[0058] The gas knife used is the Silent X-Stream Air Blade equipment, available from supplier AirFlow.

[0059] The slot die coating is carried out using the Automatic-Research TFC 300 equipment.

[0060] The blade coating is carried out using a Zehntner ZUA 2000 deposition blade.

[0061] In these examples described below, the substrate 1 and the deposition face 2 are immobile but according to a particular arrangement, the substrate 1 and therefore the deposition face 2 moves while the wet film deposition device (blade coating) and the gas flow projection device (gas knife) are stationary (case of the flexible substrate in rolled form).

[0062] First example of an embodiment of the process for manufacturing a crystalline perovskite 100 layer according to the invention by blade coating:

[0063] The steps of the process are illustrated in Figures 1 to 3. Figure 1 illustrates step a) of the process, which consists of providing a substrate 1 having a deposition face 2 on a heated platform 3 in a controlled atmosphere chamber (temperature of approximately 21°C and a relative humidity of approximately 20%). In the context of the preparation of photovoltaic devices, the substrate 1 used is a structure (5 cm x 5 cm) consisting of a glass support 7 (thickness 1.1 mm), coated with a layer of ITO 8 (indium tin oxide layer approximately 220 nm thick) itself coated with a layer of SnO2 9 (tin oxide) prepared for the fabrication of a NIP-type solar cell (illustrated in Figure 6). Typically, the SnO2 layer is first deposited by spin coating or slot-die coating and then dried at 80°C for one minute. It has a thickness of approximately 50 nm and a roughness of approximately 5 nm.

[0064] A substrate 1 consisting of a PIN-type solar cell structure can also be used, as can a substrate 1 for fabricating a tandem-type structure using silicon. In the case of a PIN-type architecture, a self-assembled monolayer of 2-Pacz (or [2-(9H-Carbazol-9-yl)ethyl]phosphonic acid supplied by TCI America - CAS number: 20999-38-6) forms the hole-extracting layer 11. This layer 11 is deposited by spin-coating onto the ITO Glass substrate, which has been previously treated with UV-ozone.

[0065] A heat treatment is applied via the heating platform 3 to the substrate 1 through the face opposite the deposition face 2. This heat treatment is controlled so that the temperature of the deposition face 2 of the substrate 1 is maintained at about 40°C.

[0066] A precursor solution is prepared from the following quantities of precursors: Pbl2 (3.707 g), PbBr2 (1.453 g), FAI (1.631 g), Csl (0.468 g), and additive FAC1 (9.7 mg), dissolved in 12 mL of a solvent mixture composed of 10.8 mL of DMF and 1.2 mL of DMSO. The concentration of Pb in the solution is approximately 1 M, the molar ratio of Cs to Pb is approximately 15%, and the molar ratio of FAC1 to Pb is approximately 0.1%.

[0067] After stirring the precursor solution at approximately 40°C for about 12 hours, the coating is applied by a blade coating device to a deposition face 2 of the substrate 1, which is at a temperature of approximately 40°C. The distance between the spreading blade 4 of the blade coating device and the deposition face 2 of the substrate 1 is approximately 70 micrometers. The relative velocity between the deposition face 2 and the spreading blade 4 is 20 mm / s, and the ink volume used is 20 microliters. The nitrogen stream is applied to the exposed surface of the wet film 5 at a speed of approximately 137 m / s. The nitrogen stream's projection nozzle 6 is arranged so that the length L of the gas stream path is approximately 3.6 mm. The nozzle 6 moves at a speed of 5 mm / s.

[0068] The projection nozzle 6 is oriented so that the nitrogen flow is projected at an angle α of 50° with the exposed surface of the wet film 5. According to a step d) (not shown) of the process, a heat treatment lasting 5 minutes at a temperature of 100°C under an inert atmosphere is carried out after the passage of the projection nozzle. A layer of crystalline perovskite 100 with the empirical formula Cso.i5FAo.79Pb(I 0.731^0.22)2.94 is obtained with high quality (the precision concerning the empirical formula values ​​is limited to two decimal places).

[0069] Extended annealing tests were also carried out, with a total annealing time of 60 minutes at 100°C, always under an inert atmosphere.

[0070] Second example of an embodiment of the process for manufacturing a crystalline perovskite 100 layer according to the invention by blade coating:

[0071] In this second example, the precursor solution contains the following quantities of precursors: Pbl2 (3.707 g), PbBr2 (1.453 g), FAI (1.631 g), Csl (0.468 g), and FAC1 (48.3 mg) dissolved in 12 mL of a mixture composed of 10.8 mL of DMF and 1.2 mL of DMSO. The concentration of Pb in the solution is approximately 1 M, the molar ratio of Cs to Pb is approximately 15%, and the molar ratio of FAC1 to Pb is approximately 0.5%.

[0072] The other parameters described for the first embodiment are identical for this second embodiment.

[0073] Although not described in the examples, the deposition of the precursor solution by slot die coating is a possible deposition method.

[0074] Analyses and measurements carried out on the perovskite layers formed according to The manufacturing process of the invention:

[0075] Different layers of perovskite 100 were fabricated by a blade coating device for FACl / Pb molar ratios of 0.1 and 0.5% in NIP (Figures 8 and 9) and PIN (Figures 11 and 12) architectures (the other elements remaining unchanged). The same analyses were also performed on layers prepared from a precursor solution not containing the FAQ additive, and these serve as a reference ([Fig. 7] for NIP and [Fig. 10] for PIN).

[0076] X-ray diffraction (XRD) analyses of the formed layers show that a polycrystalline perovskite 100 layer (alpha phase, or so-called black phase) is indeed present whether at 0.1 or 0.5% molar ratio of FAQ with a total absence of a delta phase (or so-called yellow, undesirable phase).

[0077] Furthermore, a 0.5% rate of the FAQ additive makes it possible to limit, or even eliminate The appearance of the Pbl2 signal (between 12.5° and 13°) in both NIP and PIN architectures (see [Fig. 9] or 12) is absent, while this signal is present for the reference solution ([Fig. 7] or 10) and for the solution with a FAC1 / Pb molar ratio of 0.1%. Furthermore, the Pbl2 peak is increased with prolonged annealing at 60 minutes at 100°C (not shown). Interestingly, for this FAC1 concentration of 0.5%, the Pbl2 peak is also not observed after prolonged annealing (total duration of 60 minutes - not shown).

[0078] Implementation of the perovskite layers prepared according to the invention in solar cells: PIN configuration:

[0079] The perovskite layers 100 prepared as previously described are deposited on substrates 1 comprising a glass support 7, an ITO layer 8 (transparent electrode) / an SnO2 layer 9 (electron extracting layer) in the shape of a 5 cm x 5 cm square. To complete the fabrication of the device, a hole-extracting layer 11 commonly called a 'holes extracting layer' of doped AA PT is deposited by spin-on deposition onto the perovskite layer 100, and then a top gold electrode 12 is vaporized onto the surface (refer to the stacking diagram in [Fig. 6]). PIN configuration:

[0080] In this alternative configuration, the perovskite layers prepared as described above are deposited onto substrates comprising a glass support, an ITO layer (transparent electrode) / a self-assembled monolayer of 2-PACz (or [2-(9H-Carbazol-9-yl)ethyl]phosphonic acid supplied by TCI America - CAS number: 20999-38-6) forming the hole extracting layer, which is 5 cm x 5 cm square. To complete the fabrication of the device, an electron extracting layer of C6O, then a layer of BCP (or Bathocuproine, a derivative of 1,10-phenantroline, supplied by Sigma Aldrich - CAS number 4733-39-5) and a top silver electrode are evaporated onto the surface.

[0081] The photovoltaic performance of the 200 solar cells was measured at 25 °C under standard irradiance conditions (1000 W.m2, AM 1.5 G) using a Newport solar simulator. Current-voltage curves were recorded using a Keithley recorder. The results are shown in Table 1 below.

[0082] The first line of Table 1 reports the results obtained for a perovskite layer deposited by the Dr. Blade process in a NIP architecture without the FAQ additive and serves as a reference. The results of the first example of the realization of a perovskite layer- Rovskite 100 with additive (Dr Blade coating as previously described) in NIP architecture are listed in the second row of Table 1. These devices were prepared as modules comprising 8 strips connected in series with a total active area of ​​10 cm2.

[0083] The third row of Table 1 shows the results obtained from 200 cells prepared in a PIN architecture without the FAQ additive and serves as a reference. The results of fabricating a 100 perovskite layer with the additive (Dr Blade coating as previously described) in a PIN architecture are recorded in the fourth row of Table 1. These devices were prepared as unit cells with a surface area of ​​33 mm².

[0084] [Tables 1] Deposition Conditions VOc (mV) Jsc (mA.cm-2) FF (%) PCE (%) Blade Coating® Deposition (Pb IM - Cs / Pb 15%) NIP Architecture Reference Without Additive 9280 2.54 69.4 16.4 Blade Coating® Deposition (Pb IM - Cs / Pb 15%) NIP Architecture With Additive FAQ 0.5% 9635 2.44 77.5 18.2 Blade Coating® Deposition (Pb IM - Cs / Pb 15%) PIN Architecture Reference Without Additive 1028 19.5 67.4 13.5 Blade Coating® Deposition (Pb IM - Cs / Pb 15%) PIN Architecture With Additive FAQ 0.5% 1073 20.8 66.2 14.8

[0085] ® Best result obtained for cells prepared in the form of cells unit area 33 mm2

[0086] (2) Best result obtained for cells prepared in the form of modules comprising 8 strips connected in series.

[0087] From reading the table, it can be seen that the performance of the solar cells The 200 is increased for the perovskite layer obtained with the FAQ additive. The presence of the additive notably allows for a significant improvement in the Voc, whether in NIP or PIN configuration. Thus, the 100 perovskite layers obtained according to the process of the present invention are of high quality and can be used in highly efficient perovskite solar cells.

[0088] In conclusion, the invention optimizes the manufacturing process of a multi-cation perovskite layer. It enables the formation of a high-quality crystalline layer under conditions suitable for an industrial application. The integration of these layers into solar cell-type devices is possible and leads to very good results.

Claims

Demands

1. A method for manufacturing a multi-cation perovskite layer (100) for forming a photoactive layer, the method comprising the steps of: - a) supplying a substrate (1) having a deposition face (2), - b) deposition of a precursor solution comprising at least one solvent and perovskite precursors so as to form a wet film (5) on the deposition face (2), the deposition being effected by coating via a flat die or by sheet coating, the precursors comprising at least CsX, FAY, PbZ2, with X, Y and Z = I, Br, and an additive FAQ, the amounts being determined such that the molar ratio of cesium to lead is between about 4% and 22%, preferably between 13% and 20%, and the molar ratio of FAQ to lead is between 0.1% and 5%, in particular between 0.1% and 2%, and that the perovskite layer (100) has a general formula of the type Cs%Ad x+WJPb(IvBr( i .J; with x between 0.04 and 0.22, including between 0 and 1, and w between 0.001 and 0.05, and - c) sweeping an exposed surface of the wet film (5) with a stream of dry air or inert gas having a velocity greater than or equal to 120 m / s so as to crystallize the multi-cation perovskite layer (100), the process further comprising applying a heat treatment to the substrate (1) so that the deposition face (2) has a temperature ranging from about 25°C to at least 80°C during step b).

2. A manufacturing method according to the preceding claim, wherein the application of a heat treatment to the substrate (1) is carried out such that the deposition face (2) has a temperature ranging from approximately 30°C to 70°C, and preferably from approximately 40°C to 60°C.

3. A manufacturing process according to any one of claims 1 to 2, wherein the precursors of the perovskite layer (100) are selected from a combination of CsX, FAY and PbZ2, with X, Y and Z = I, Br and the additive FAQ.

4. A manufacturing method according to any one of the preceding claims, in in which at least one solvent is chosen from DMF and / or DMSO.

5. A manufacturing process according to any one of the preceding claims, wherein the molar concentration of lead in the precursor solution is between 0.5 M and 1.7 M.

6. A manufacturing process according to any one of the preceding claims, wherein the only thermal budget applied during the manufacturing process is provided by the heat treatment applied to the substrate (1) such that the deposition face (2) has a temperature ranging from about 25°C to 80°C during steps b) and c).

7. A manufacturing method according to any one of claims 1 to 5, wherein step c) of applying the inert gas or dry air stream is followed by step d) of applying a thermal anneal carried out at a temperature between 70°C and 100°C.

8. A manufacturing method according to any one of claims 1 to 7, wherein step c) of scanning by a flow of inert gas or dry air is carried out by a relative displacement of the substrate (1) comprising the wet film (5) and a projection nozzle (6), such as a projection nozzle of a gas knife, the projection nozzle being arranged so that the length (L) of the path of the flow of inert gas or dry air between the outlet of the projection nozzle (6) and the exposed surface of the wet film (5) is between about 3.1 millimeters and 6 millimeters, and preferably between about 3.1 millimeters and 4 millimeters.

9. A manufacturing method according to the preceding claim wherein the relative displacement velocity between the wet film (5) and the projection nozzle (6) during step c) is between 1 and 50 mm / s and preferably between 5 and 30 mm / s.

10. A manufacturing method according to claim 8 or 9, wherein the deformed angle between the inert gas or dry air flow and the wet film is between 90° and 45°.

11. A manufacturing method according to any one of the preceding claims wherein step b) of depositing the precursor solution is carried out so as to obtain a constant wet film thickness (5) of between 2 and 16 micrometers preferably between 2.5 and 8 micrometers and preferably still between 3 and 5 micrometers.

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