Process for producing a controlled composition organic-inorganic hybrid perovskite layer

Abstract

Process for the fabrication of a controlled composition organic-inorganic hybrid perovskite layer. This description relates to a process for the fabrication of an organic-inorganic perovskite layer comprising the following steps: Formation of an inorganic precursor layer on a substrate; Implementation of a short-distance sublimation step from a powder comprising the organic precursors, whereby the vapors from the organic precursor layer react with the inorganic precursor layer and an organic-inorganic hybrid perovskite layer is formed; the organic precursor powder being obtained by mechanosynthesis by co-milling at least a first group of particles into a first material and a second group of particles into a second material, until a third group of particles is formed into a third material, the third group of particles forming the organic precursor powder.Figure for the abridged version: Fig. 1.

Description

Title of the invention: Method for producing an organic-inorganic hybrid perovskite layer of controlled composition Technical field

[0001] The present description relates generally to the field of organic-inorganic hybrid perovskites, and more particularly to their production process.

[0002] The invention finds applications in numerous industrial fields, in particular in the photovoltaic field, or for the manufacture of electronic, optical or optoelectronic devices, in particular for the manufacture of light-emitting diodes (LEDs), photo-detectors, scintillators, X-ray detectors for example for medical purposes or even transistors.

[0003] The invention is particularly interesting since it makes it possible to form layers of perovskites of controlled composition with relatively short deposition times. Prior art

[0003] Organic-inorganic hybrid perovskites are particularly interesting materials for photovoltaic cells, and in particular for tandem photovoltaic cells on silicon.

[0004] Among the particularly promising organic-inorganic hybrid materials, we can cite ABX3 type materials with A representing a cation or a mixture of cations chosen from Cs+, FA+ (with FA= CH5N2), MA+ (with MA = CH3-NH3), B a metal cation chosen from Pb, Sn, Ge and X a halogen chosen from Cl, Br and I.

[0005] Generally, the processes for producing hybrid perovskite layers are carried out in two stages: the inorganic part of the perovskite is deposited first and then is caused to react with the organic part to form the perovskite.

[0006] For example, in the article by Sahli et al. (Nature Materials 2018, 17, 820826), a layer of perovskite material of formula CsxFAi xPb(I,Br)3 is obtained by first forming a porous layer by co-evaporation of lead iodide (Pbl2) and cesium bromide (CsBr). Then an organohalide solution comprising formamidinium iodide (FAI) and formamidinium bromide (FABr) is deposited by spin-coating. After annealing at 150 °C in ambient air, the perovskite is crystallized.

[0007] In the article by Zhang et al. (ACS Appl. Energy Mater. 2022, 5, 5797-5803), Cs0.i4FA0.86Pb(BrxIi_x)3 films are also obtained by implementing a two-step process. In a first step, inorganic layers of CSI and Pbl2 are sequentially deposited on a substrate. In a second step, An organic FAI film or an organic FAI / FABr film is prepared by spray depositing an ethanol solution comprising the precursors. This film is used to carry out a close space sublimation (CSS) step at a temperature of 160°C. During this step, the material is sublimated, which allows the organic vapors to react with the CSI and Pbl2 layers and thus form the perovskite material.

[0008] In CSS processes, it is also known that it is possible to use a precursor powder, for example in the form of a solid wafer (target). Such a process is easy to implement in the case where there is only one precursor. However, in the case where there are two different precursors, for example FAI particles and FABr particles, the process is more difficult to implement.

[0009] Indeed, the maximum admissible temperature in a CSS process must be lower than the melting temperature of the target. However, the melting temperature of FAI is 242°C and that of FABr is 135°C. Thus, above 125°C, partial melting of the target and / or attachment to the susceptor is observed.

[0010] Furthermore, if the working temperature is too low, the reaction kinetics are less rapid and the duration of the process can be considerably extended.

[0011] Furthermore, since the sublimation of FABr occurs at a lower temperature than that of FAI, the FABr / FAI ratio in the atmosphere is higher than that of the target, which leads to two major problems. First, controlling the amount of FABr / FAI ratios in the target to obtain the desired Br level in the perovskite is difficult to determine since the FABr / FAI ratio in the atmosphere is different from that of the target.

[0012] Then, the composition of the target evolves over time since the FABr preferentially sublimes to the FAI, which modifies the FABr / FAI ratio in the target over time. The deposited material therefore has neither a homogeneous composition nor the desired composition. Summary of the invention

[0013] There is therefore a need to obtain a method for forming a layer of organic-inorganic hybrid perovskite whose composition is controlled.

[0014] This aim is achieved by a method for producing an organic-inorganic perovskite layer comprising the following steps: - Formation of a layer of inorganic precursors on a substrate, - Implementation of a short-distance sublimation step from an organic precursor powder, whereby the vapors of the organic precursor powder react with the inorganic precursor layer and an organic-inorganic hybrid perovskite layer is formed, the organic precursor powder being obtained by mechanosynthesis, by co-grinding at least a first group of particles into a first material and a second group of particles into a second material, until a third group of particles into a third material is formed, the third group of particles forming the organic precursor powder.

[0015] The invention differs fundamentally from the prior art in that the second step of the process is carried out with a powder of inorganic precursors obtained by mechanosynthesis.

[0016] The powder obtained by mechanosynthesis comprises particles whose composition corresponds to the composition that it is desired to react with the layer of inorganic precursors previously deposited. The particles are preferably single-phase.

[0017] Thus, when the third material is sublimed during step b), the vapors of the third material react with the layer of inorganic precursors to form the perovskite.

[0018] The use of particles obtained by mechanosynthesis is particularly interesting from an industrial point of view because, as the particles forming the powder all have the same composition, this makes it possible to increase the temperature of the CCS step and therefore to reduce the duration of this step.

[0019] For example, the melting temperature of FA(Ii.yBry) is between that of FAI and FABr.

[0020] In addition, the vapors generated during the CCS step always have the same composition because the composition of the target remains constant during the process. The perovskite material thus formed is homogeneous and has the desired composition.

[0021] Advantageously, the organic-inorganic hybrid perovskite has the formula A' bx AxBX3 with. A' an inorganic cation or an alloy of inorganic cations, preferably chosen from Cs, Rb, K and Na, To a monovalent organic cation or an alloy of monovalent organic cations, preferably chosen from methylammonium (MA), formamidinium (FA), guanidinium (GA), dimethylammonium (DA) and rimidazolium (IA), even more preferably A corresponds to MA and / or FA, B an inorganic cation or an alloy of inorganic cations, preferably chosen from Pb, Sn and Ge, X one or more halogens, preferably chosen from Cl, Br, I and F.

[0022] Advantageously, the organic-inorganic hybrid perovskite has the formula Cs, x MAxPb(Ii yBry)3, Csj xFAxPb(Ij y zBryClz)3 or Csj xFAxPb(L yBry)3, Csj xFAxPbo.5Sno.5(Ii y Bry)3, Csi x zMAxFAzPb(Ii yBry)3 or Cskx_zMAxFAzPbkkSnkIi_yBry)3 with 0 <y<l,0<k <l,O<x<l,O<z<letO< x+z < 1, et de préférence 0<y<let0<x<l.

[0023] Advantageously, the organic precursor powder comprises particles of formula AX with A representing a monovalent organic cation or an alloy of monovalent organic cations, preferably MA and / or FA, X representing one or more halogens chosen from Cl, Br, I and F. In addition, A represents an alloy of monovalent organic cations and / or X represents several halogens.

[0024] Advantageously, the organic precursor powder is a FA(Ii yBry) powder or a MA(Ii yBry) powder with 0 < y < 1. Such powders can be formed by mechanosynthesis, respectively, from a FAI powder and a FABr powder or from a MAI powder and a MABr powder.

[0025] Advantageously, the layer comprising the inorganic precursors is a layer containing Pb, Cs and one or more halogens chosen from iodine, bromine and chlorine.

[0026] For example, the inorganic precursor layer is a layer of Pbl2 and Csl, a layer of Pbl2 and CsBr, a layer of PbBr2 and Csl, a layer of PbBr2 and CsBr, a layer of Pbl2, PBBr2 and Csl, a layer of Pbl2, PBBr2 and CsBr, a layer of Pbl2, Csl and CsBr, a layer of PbBr2, Csl and CsBr or a layer of PbBr2, Pbl2, Csl and CsBr. Preferably, it is Pbl2 and CsBr or Pbl2 and Csl.

[0027] Advantageously, the organic precursor powder can be in the form of a solid target or a bed of powders.

[0028] According to an advantageous embodiment variant, the layer of inorganic precursors is formed by thermal evaporation or deposition with a spinning wheel.

[0029] According to another advantageous embodiment variant, the layer of inorganic precursors is formed by CSS.

[0030] Advantageously, the substrate is a substrate suitable for the photovoltaic field. For example, it may be a glass, plastic or metal substrate.

[0031] Advantageously, the substrate is a silicon substrate, preferably a textured silicon substrate. Such a substrate is particularly interesting for forming a photovoltaic device.

[0032] The invention also relates to a method for manufacturing a multi-junction photovoltaic cell comprising at least one perovskite photovoltaic cell or a single-junction perovskite photovoltaic cell, the method comprising the production of an organic-inorganic perovskite layer according to the method as described above.

[0033] The multi-junction photovoltaic cell comprising at least one perovskite photovoltaic cell is, for example, a perovskite-silicon tandem photovoltaic cell, a perovskite-perovskite tandem photovoltaic cell, a perovskite-perovskite-silicon triple junction photovoltaic cell or a photo- voltaic triple junction perovskite-perovskite-perovskite. Brief description of the drawings

[0034] These characteristics and advantages, as well as others, will be explained in detail in the following description of particular embodiments given without limitation in relation to the attached figures among which:

[0035] [Fig.l] schematically represents in section a part of a short-distance sublimation furnace device according to a particular embodiment of the invention;

[0036] [Fig.2] schematically represents in section a short-distance sublimation oven according to another particular embodiment of the invention;

[0037] Figures 3A and 3B are schematic and sectional representations, respectively, of a single junction photovoltaic cell and a tandem photovoltaic cell, according to different particular embodiments of the invention;

[0038] [Fig.4] is a graph representing X-ray diffractograms of a FA(Ii yBry) powder with y~0.5 obtained by mechanosynthesis according to a particular embodiment of the invention, as well as of a FAI powder, a FABr powder and a powder obtained by simple mixing of FAI and FABr, the latter being given for comparison. Description of the embodiments

[0039] The same elements have been designated by the same references in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same references and may have identical structural, dimensional and material properties.

[0040] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been shown and are detailed.

[0041] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "upper", "lower", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made unless otherwise specified to the orientation of the figures.

[0042] Unless otherwise specified, the expressions "about", "approximately", "substantially", and "of the order of" mean to within 10%, preferably to within 5%.

[0043] The process that we will subsequently describe in more detail, with reference to Figures 1 and 2, concerns the production of a layer of organic-inorganic hybrid perovskite.

[0044] The organic-inorganic hybrid perovskite preferably has the general formula A' | XAxBXï with: A' an inorganic cation or an alloy of inorganic cations, preferably chosen from Cs, Rb, K and Na, To a monovalent organic cation or an alloy of monovalent organic cations, selected from CH3NH3+ (methylammonium or MA), CH(NH2)2+ (formamidinium or FA)), C(NH2)3+ (guanidinium or GA), C2H8N (dimethylammonium or DA), C3H5N2 (imidazolium or IA); an alloy of monovalent organic cations may be, for example, MAbxFAx with 0 <x<l), B an inorganic cation or an alloy of inorganic cations, preferably chosen from Pb, Sn and Ge, X one or more halogens, preferably chosen from Cl, Br, I and F.

[0045] Preferably, A' represents Cs.

[0046] Preferably, A represents MA and / or FA.

[0047] Preferably, B represents Pb, Sn and Ge,

[0048] Preferably, X represents Br and / or I.

[0049] Advantageously, the organic-inorganic hybrid perovskite has the formula Cs,x MAxPb(Ij yBry)3, Csi xFAxPb(Ii y zBryClz)3or Csj xFAxPb(Ij yBry)3or Csj xFAxPb.3SnoAI i yBry)3 or Csi x zMAxFAzPb(Ii yBry)3 orCskx_zMAxFAzPbi_kSnkIiyBry)3with 0 < y < 1.0 <k<l,0<x<l,0<z<let0< x+z < 1, et de préférence 0<y<let0<x<l.

[0050] The method comprises the following steps: a) Formation of a layer of inorganic precursors 11 on a substrate 10, b) Carrying out a short-distance sublimation step from a powder 20 comprising the organic precursors, the powder 20 being obtained by mechanical synthesis, the distance between the powder 20 of organic precursors and the substrate 10 being, for example, between 0.1 and 5 mm, whereby the organic precursors react with the layer of inorganic precursors 11 and a layer of organic-inorganic hybrid perovskite is formed (Figures 1 and 2).

[0051] The powder 20 used in step b) is prepared during a step, prior to step b), for example between step a) and step b), or preferably before step a).

[0052] The preparation of the powder 20 is carried out according to the following sub-steps:

[0053] - providing at least a first group of particles in a first material and a second group of particles in a second material,

[0054] - carry out a sub-step of mechanosynthesis by co-grinding at least the first group of particles and the second group of particles, until a third group of particles is formed in a third material.

[0055] The final powder 20 mainly comprises, and preferably consists of, the third group of particles. The composition of these particles corresponds to the composition to be reacted with the precursor layer deposited during step a).

[0056] The mechanosynthesis sub-step is therefore carried out by co-grinding several powders.

[0057] Co-grinding is carried out with at least two groups of particles. It could also be carried out with more than two groups of particles (for example three or four groups of particles).

[0058] The mechanosynthesis sub-step consists of carrying out very energetic co-grinding of the pure or pre-alloyed materials in a high-energy mill until a powder 20 is obtained whose particles are single-phase or polyphase. Preferably, the particles are single-phase.

[0059] Co-grinding is carried out in a planetary ball mill. The mass of balls is at least twice the mass of powders, for example at least 15 times greater.

[0060] The grinding rotation speed is high (typically from 100 rpm to 700 rpm, for example 500 rpm). It depends on the grinder used as well as the mass of balls and powders. The grinding time is for example between 10 min and 5 h, for example 1 h.

[0061] The mixture may be an equimolar mixture.

[0062] The organic precursor powder obtained by mechanosynthesis comprises, and preferably consists of, particles of general formula AX with A a monovalent organic cation or an alloy of monovalent organic cations, preferably MA and / or FA, X representing one or more halogens chosen from Cl, Br, I and F. In this general formula, A represents an alloy of monovalent organic cations and / or X represents several halogens.

[0063] Preferably, A is an alloy of monovalent organic cations and X an alloy of halogens.

[0064] From this powder, it is possible by CSS to synthesize a perovskite layer of general formula A' LxAxBX3 with A' is an alloy of inorganic cation (Cs, Rb, K, Na), 0 <x<l et B un cation (Pb) ou alliage de cations inorganiques (Pb, Sn, Ge).

[0065] According to a particular embodiment, the powder 20 of organic precursors comprises particles of MA(Ii yBry) with 0 <y<l. La poudre est obtenue par mécanosynthèse à partir de MAI et de MABr. Elle peut, par exemple, servir pour former des couches de Csi xMAxPb(Ii yBry)3.

[0066] According to another particular embodiment, it is possible for example to obtain a powder 20 in MAzFAi zIi yBry (with 0 <z<l et 0<y< 1 ) à partir de poudres de MABr et / ou MAI et / ou FABr et / ou FAI. La mécanosynthèse de ces poudres permet de former, par exemple, des couches de CsxMAzFAi z xPb(Ii yBry)3.

[0067] According to another particular embodiment, it is possible to use FAI and / or FABr and / or FAQ powders to form powders 20 in FAL y zBryClz (with 0 <y<l et 0<z<l)par exemple pour former des couches de Csi xFAxPb(Ii y zBryClz)3.

[0068] The powder 20 obtained can be used as it is, in particular in the form of a bed of powders.

[0069] According to an advantageous embodiment variant, the powder 20 obtained is used to manufacture a solid target (also called a wafer). For this, the powder 20 is pressed, for example with a hydraulic press with P ~ IxlO7 Pa). The pressing of the target can be done by heating the powder.

[0070] During step a), the inorganic precursors of the perovskite are deposited on the substrate 10 to form a layer 11 of inorganic precursors. Preferably, the precursors contain lead and cesium. Lead halides and cesium halides are advantageously used.

[0071] Preferably, the inorganic precursors are chosen from the following materials: CsCl, CsBr, Csl, PbCl2, PbBr2 and Pbl2, with, preferably, at least one Cs halide and one Pb halide. It may be a combination of two, three or more precursors.

[0072] For example, the inorganic precursors are chosen from one of the following combinations: a combination of two materials such as Pbl2 and Csl, Pbl2 and CsBr, PbBr2 and Csl, PbBr2 and CsBr, or a combination of three materials Pbl2, PBBr2 and Csl or Pbl2, PBBr2 and CsBr or Pbl2, CSI and CsBr or PbBr2, CSI and CsBr or a combination of four materials PbBr2, Pbl2, CSI and CsBr. Preferably, it is Pbl2 and CsBr or Pbl2 and Csl.

[0073] The layer of inorganic precursors 11 is, for example, deposited by thermal evaporation or spin coating.

[0074] According to a particular embodiment, the layer of inorganic precursors 11 can also be deposited by CSS.

[0075] The layer of inorganic precursors has a thickness of a few hundred nanometers, for example 300 nm.

[0076] The substrate used may be a glass, polymer (polyimide for example), or steel substrate. Preferably, it is made of silicon. The silicon substrate may be textured or non-textured. It may be polished.

[0077] Advantageously, the substrate is functionalized with a layer or stack of insulating, conductive or semi-conductive layers to inject and / or collect charges in the perovskite material.

[0078] The second step consists of reacting the inorganic precursor layer 11 with the organic precursors to form the perovskite. This step is carried out by CSS.

[0079] The substrate 10 covered by the layer 11 of inorganic precursors is positioned facing the powder 20 of organic precursors (bed of powders or target formed of agglomerated particles).

[0080] The assembly is heated under vacuum (e.g. 50-100 Pa). The distance between the powder 20 of organic precursors and the substrate 10 is, for example, between 0.1 and 5 mm.

[0081] The organic precursors change state and pass into gaseous form (represented by arrows in [Fig. 1]) and they react with the layer 11 inorganic precursors to form the organic-in-organic hybrid perovskite material.

[0082] Step b) is carried out in a short-distance sublimation oven.

[0083] A lamp oven can be used to carry out this step.

[0084] For example, as shown in [Fig. 2], the CSS oven 100 comprises a reactor 102 around which a heating system is positioned. For example, it may be lamps 104 ([Fig. 2]) or any other heating system (e.g., resistance).

[0085] The reactor 102 can be made of quartz, graphite, or metal.

[0086] The reactor 102 may be tubular.

[0087] As shown in Figures 1 and 2, the furnace 100 also includes a susceptor 106 (also called a source block) and a cover 108 (also called a substrate block). The susceptor 106 and the cover 108 are made of thermally conductive materials that can withstand pressure, vacuum, and high temperatures. They are preferably made of graphite.

[0088] The substrate 10 and the target 20 are positioned between the susceptor 106 and the cover 108.

[0089] Preferably, the substrate 10 is in direct contact with the cover 108 which maintains its temperature at the set value.

[0090] The powder 20 of organic precursors is placed on the susceptor 106.

[0091] The substrate 10 is at a short distance from the powder 20. By short distance, we mean a distance typically of 0.1 mm to 20 mm, preferably of 1 mm to 7 mm, for example of 0.1 mm to 5 mm or of 3 mm to 5 mm. In particular, a distance of 1 mm may be chosen.

[0092] One or more spacers 112, which may be made of a thermal insulating material (for example glass, quartz, or alumina) serve to keep the substrate 10 at a short distance from the powder 20.

[0093] The cover 108 can be held pressed against the substrate by a closure system in the susceptor 106 not shown (for example a screw or any other fixing system).

[0094] The susceptor 106 and the cover 108 each have a thermocouple 114 or any other system (pyrometer, etc.) to measure and control their temperature.

[0095] A heating system (lamp, resistors, etc.) makes it possible to regulate the temperature of the susceptor 106 (Ttarget) and the cover 108 (Tsubstrate) in a range which can go from 20°C to 600°C. Temperature rise ramps can be controlled in a range, for example, from 0.1°C / s to 10°C / s. The susceptor 106 (Ttarget) and the cover 108 (Tsubstrate) can be controlled by temperature ramps (or sequences of ramps), independently. Thus, it is possible to adjust the sublimation kinetics of the powder 20 and the reaction temperatures with the inorganic layer deposited on the substrate 10 so as to control the morphology of the layer and / or the duration of the process.

[0096] The device 100 is connected to a system with an inert gas supply 116 (such as argon or N2).

[0097] The device 100 can also be connected to an oxidizing gas supply (such as O2) or to a reducing gas supply (such as H2).

[0098] The device 100 comprises a gas outlet 122, connected to a pumping system making it possible to achieve a vacuum Pfour ranging, for example, from 0.00001 Pa - 1 Pa. The value Pfour depends on the CSS furnace used.

[0099] During step b), the target is sublimated. The sublimation deposition is carried out by heating the susceptor 106 and the cover 108 under vacuum.

[0100] During step b), the temperature of the target may be identical to the temperature of the substrate.

[0101] According to an alternative embodiment, during step b), the temperature of the substrate Tsub is advantageously lower than the temperature of the target Tcible in order to create a thermal gradient while promoting a greater partial pressure of organic compound without risking decomposition of the perovskite. The temperature difference Tcible - Tsub is from 1°C to 350°C (for example from 1 to 100°C, in particular 20°C), preferably from 50°C to 300°C and even more preferably from 100°C to 250°C, for example 150°C.

[0102] According to another embodiment variant, during step b), Ttarget < Tsubstrate to promote condensation of the vapor on the substrate and thus accelerate the reaction. The temperature difference may be from 1 to 100°C, for example 20°C.

[0103] The target temperatures depend on the material to be sublimated.

[0104] The perovskite layers obtained can be used in many industrial fields, in particular, in the field of X-ray detection for medical, safety, security, radiation protection, or large scientific instruments, but also in the field of photovoltaics, detection of gamma radiation, ionizing radiation (alpha, beta, neutron) or even for the manufacture of electronic, optical or optoelectronic devices, in particular for the manufacture of light-emitting diodes (LEDs), photo-detectors, scintillators or even transistors.

[0105] In particular, the method is applicable for depositing gold hybrid perovskites thin inorganic materials (between 10 nm and 5000 nm). These materials are generally used for visible or near infrared optical applications. These include photovoltaic applications, but also infrared and near infrared detection or light emission in the visible, near infrared and infrared wavelengths.

[0106] Advantageously, with regard to photovoltaic applications, the method described above can be used to produce a layer of organic-inorganic hybrid perovskite material in a photovoltaic cell.

[0107] By varying the amount of iodine and bromine in the perovskite material, it is possible to modify the band gap energy.

[0108] Photovoltaic cells can be single junction cells or multi-junction cells.

[0109] For example, a single junction pin-type photovoltaic cell may comprise, from the rear face to the front face ([Fig.3A]): - an upper electrode 210, - a buffer layer 220, - a layer of type n 230, - an active layer of perovskite 240, - a layer of type p 250, - a layer of transparent conductive oxide 260, - a substrate 270.

[0110] Preferably, the photovoltaic cell is made up of the different elements mentioned above.

[0111] The front face of the photovoltaic cell is intended to receive a luminous flux.

[0112] The incident radiation is represented by arrows in [Fig.3A].

[0113] The upper electrode 210 is, for example, made of Ag, Cu, Ni, Al.

[0114] The buffer layer 220 may be a layer of LiF, SnS, metal oxide or BCP (bathocuproine).

[0115] The layer of type n 230 can be for example in C60, PC61BM ([6,6]-phenyl-C61-methyl butanoate or “[6,6]-phenyl-C61-butyric acid methyl ester”), PC71BM ([6,6]-phenyl-C71-methyl butanoate or “[6,6]-phenyl-C71-butyric acid methyl ester”), PCBM / C60 or PCBM / C. Preferably, it is in C60.

[0116] According to other embodiment variants, the n-type layer 230 may be an oxide layer, for example SnOx (with x between 1 and 2), ZnO, Al:ZnO, ITO or IZO.

[0117] The active layer 240 is a perovskite active layer obtained by the method described above. Preferably, the perovskite layer is a perovskite of the APbX3 type with A representing methylammonium, dimethylammonium, formamidinium, guanidinium or cesium cations (the aforementioned cations can be used alone). or in mixture) and X representing halide anions (preferably chlorine, bromine, iodine anions alone or in mixture).

[0118] The active layer 240 has, for example, a thickness of between 200 nm and 1.5 pm.

[0119] According to a first variant, the p-type layer 250 may be a layer of poly(3,4-ethylenedioxythiophene) (PEDOT) or poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA).

[0120] According to a second variant, the p-type layer 250 is a self-assembled layer (or SAM for “Self-Assembled Monolayer”). The SAM layer may be a layer of 2PACz ([2-(9H-Carbazol-9-yl)ethyl]phosphonic acid), 3PACz (3-(9H-carbazol-9-yl)propyl)phosphonic acid), 4PACz (4-(9H-carbazol-9-yl)butyl)phosphonic acid), Me-4PACz (acid (4-(3,6-Dimethyl-9H-carbazol-9-yl)butyl)phosphonic acid), MeO-2PACz ((2-(3,6-Dimethoxy-9H-carbazol-9-yl)ethyl)phosphonic acid), 6dPA (acid 1,6-hexylenediphosphonic acid) or a layer of MPA (methylphosphonic acid) or a layer obtained from a mixture of these molecules. It can also be one of their derivatives.

[0121] According to a third variant, the p-type layer 250 is an oxide layer, for example a MoOx layer, a NiOx layer.

[0122] According to another variant, the p-type layer 250 may be an oxide / SAM bilayer, for example a NiOx / SAM bilayer.

[0123] The transparent conductive oxide layer 260 may be an indium tin oxide (or ITO) layer.

[0124] These different elements are positioned on a substrate 270 arranged on the rear face. The substrate 270 is, for example, made of glass.

[0125] We will now describe in more detail a Si / perovskite tandem photovoltaic cell. Such a cell comprises a lower Silicon (Si) sub-cell and an upper Perovskite (PK) sub-cell.

[0126] Such a cell is for example shown in [Fig.3B]. This structure is called “inverse” or pin type. The cell comprises from the rear face to the front face: - a first electrode 302, - a first layer of transparent conductive oxide 304, for example in ITO or AZO, - a layer of p-doped amorphous silicon 306, - possibly a layer of intrinsic amorphous silicon 308, - an active layer of crystalline silicon 310, - possibly a layer of intrinsic amorphous silicon 312, - a layer of n 314 doped amorphous silicon, - a second layer of transparent conductive oxide 316, for example ITO or AZO, - a p-type layer (HTL) 318, for example in PEDOT, PT AA, or even in oxide (MoOx or NiOx for example) or formed from a SAM, - an active layer of perovskite 320, for example of formula APbX3, - a passivation layer, for example, MgFx, AIOx, LiF, - an n-type layer (ETL) 322, for example in C60, - a buffer layer 324, for example made of BCP or oxide such as SnOx, - a third layer of transparent conductive oxide 326, for example made of ITO or AZO, - a second electrode 328, for example made of Ag, Cu, Ni or Al.

[0127] The different materials used for the upper perovskite (PK) sub-cell can be chosen, for example, from the materials previously described for the single junction cell.

[0128] The CSS deposition method is particularly suitable for forming perovskite-based solar cells on a lower Si cell. The lower cell may have a textured surface (for example, a surface in the form of pyramids 1 to 2 pm high). In the case of tandem cells on Si, this may in particular be the perovskite Csi xFAxPb(L yBry)3 with 0.65 <x<0,9 (de préférence x~0,8) et y~0,3. Le taux de Br peut être facilement ajusté pour obtenir une bande d’énergie interdite à 1,7 eV (soit 0,2 < y < 0,4).

[0129] For photovoltaic applications, the perovskite layer production process can also be used to manufacture single junction solar cells based on perovskite. In this case, the perovskite will have a band gap energy between 1.3 eV and 1.5 eV. In particular, it could be the perovskite Csi xFAxPb(Ii yBry)3 with x~0.85 and 0.05 < y < 0.25.

[0130] It is also possible to fabricate a perovskite (1.2 eV) / perovskite (1.8 eV) tandem cell by depositing a first perovskite in CS| XFAxPb()3Sn()dI| yBry)3 with x~0.85 and y~0.05 and a second in Csi xFAxPb(Ii yBry)3 with x~0.85 and y~0.5. One of the perovskite layers or both perovskite layers can be formed according to the method previously described.

[0131] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will occur to those skilled in the art.

[0132] Finally, the practical implementation of the embodiments and variants described is within the reach of those skilled in the art from the functional indications given above.

[0133] Illustrative and non-limiting example of a particular embodiment of the invention

[0134] In this example, the mechanosynthesis step is carried out by co-grinding an equimolar mixture of FAI and FABr powders in a planetary mill for 1 h at 500 revolutions / min (rpm). The powder / molecule mass ratio is less than 0.2. An X-ray diffraction characterization ([Fig.4]) shows that only the peaks related to FAI are visible. They are largely shifted to the left.

[0135] The absence of FABr-related peaks together with the shift of FAI peaks proves that Br has inserted into the FAI lattice to form a FA(IlyBry) solid solution.

[0136] For comparison, X-ray diffraction on a powder mixture shows that the signature of the FAI of the FABr is visible. This confirms that the two phases (FAI and FABr) coexist well in the powder mixture.

[0137] An organic-inorganic hybrid perovskite layer was deposited by CSS from FA(Ii yBry) powder with 0 <y<l obtenue par mécanosynthèse.

[0138] The powder used may be in the form of a solid CSS target or it is possible to place a powder bed in the CSS furnace rather than a solid target.

[0139] Several layers of organic-inorganic hybrid perovskite of formula Csi.xFAx Pb(L yBry)3 were fabricated according to the following steps: a) deposition of inorganic precursors (Pbl2 + CsBr) on a substrate to form inorganic layers of approximately 250 nm thickness containing Pbl2 and CsBr, b) CSS step from a FA(Ii yBry) powder obtained by mechanosynthesis to form the perovskite Csi xFAxPb(Ii yBry)3 from the previously deposited precursors.

[0140] For comparison, perovskites have also been produced from a target formed from simply mixed powders.

[0141] The different perovskites obtained (from the powder mixture or from the powder obtained by mechanosynthesis) were characterized by X-ray diffraction to determine the Br content in the perovskite Csi xFAxPb(Ii yBry)3. This content can be determined relative to the shift of the (101) peak at 13.9° of the perovskite structure.

[0142] They were also characterized by UV-Vis spectrometry to determine the value of the perovskite band gap.

[0143] The results are listed in the following table:

[0144] [Tables 1] [FABr] / ([FAI] + [FABr]) in target CSS CSS CSS Time CSS y-value Band gap powder mixture 12.5% ​​125°C 40 min ~ 18% 1.63 eV powder mechanosynthesis 50% 140°C 10 min -21% 1.66 eV

[0145] The FABr content of the target obtained by mechanosynthesis had to be increased compared to that of the target obtained by simple mixing of powders. Indeed, in the case of mixed powders, the FABr sublimes at a lower temperature, it reacts preferentially to form the perovskite. With the mechanosynthesis step, the powder obtained being an alloy at the atomic scale, the gas phase contains the same content of Br and I as the target. To obtain the same quantity of Br in the gas, its content in the target must therefore be increased. The mass of the target is unchanged.

[0146] In the case of the target obtained by mechanosynthesis, the process temperature could be increased from 125°C to 140°C and the process was thus shortened from 40 min to 10 min, which is a considerable advantage for applying the process on a large scale.

[0147] The properties of the layers in terms of crystallographic quality, Br content and band gap energy are similar.

[0148] Organic-inorganic hybrid perovskite layers were deposited on textured silicon substrates to fabricate tandem cells on Si.

[0149] In the case of a layer formed from a target obtained by mixing FAI+FABr, characterization by X-ray diffraction shows the presence of an iodine-rich perovskite phase and a bromine-rich perovskite phase. In the case of a layer formed from a target composed of a FAIi yBry powder obtained by mechanosynthesis, characterization by X-ray diffraction confirms the presence of a single perovskite phase with a halogen composition equivalent to that of the target.

Claims

Claims

1. A method for producing an organic-inorganic perovskite layer comprising the following steps: - Forming an inorganic precursor layer (11) on a substrate (10), - Carrying out a short-distance sublimation step from an organic precursor powder (20), whereby the vapors of the organic precursor powder react with the inorganic precursor layer (11) and an organic-inorganic hybrid perovskite layer is formed, characterized in that the organic precursor powder (20) is obtained by mechanosynthesis by co-grinding at least a first group of particles made of a first material and a second group of particles made of a second material, until a third group of particles made of a third material are formed, the third group of particles forming the organic precursor powder (20).

2. Method according to claim 1, characterized in that the organic-inorganic hybrid perovskite has the formula A' bxAxBX3 with. A' an inorganic cation or an alloy of inorganic cations, chosen from Cs, Rb, K and Na, A a monovalent organic cation or an alloy of monovalent organic cations, preferably chosen from methylammonium, for-mamidinium, guanidinium, dimethylammonium and rimidazolium, even more preferably A corresponds to MA and / or FA, B an inorganic cation or an alloy of inorganic cations chosen from Pb, Sn and Ge, X one or more halogens chosen from Cl, Br, I and F.

3. Method according to one of claims 1 and 2, characterized in that the powder (20) of organic precursors comprises particles of formula AX with A representing a monovalent organic cation or an alloy of monovalent organic cations, preferably MA and / or FA, X representing one or more halogens chosen from Cl, Br, I and F and in that A represents an alloy of monovalent organic cations and / or X represents several halogens.

4. A method according to any one of the preceding claims, characterized in that the organic-inorganic hybrid perovskite has the formula Csi xMAxPb(Ii yBry)3, Csi xFAxPb(Ii y zBryClz)3jCsi xFAxPb(Ii yBry )3, Cs1_xFAxPbo.5Sno.5(Ii-yBry)3, Cs1_x_zMAxFAzPb(I1_yBry)3 orCskx_zMAxFAz PbkkSnkIkyBry)3with 0 <y<l,0<k<l,0<x<l,0<z<let0< x+z < 1.

5. Method according to any one of the preceding claims, characterized in that the layer (11) comprising the inorganic precursors is a layer containing Pb, Cs and one or more halogens chosen from iodine, bromine and chlorine.

6. Method according to any one of the preceding claims, characterized in that the powder (20) of organic precursors is a powder of FA(Ii yBry) or a powder of MA(h yBry) with 0 < y < 1.

7. Method according to any one of the preceding claims, characterized in that the powder (20) of organic precursors can be in the form of a solid target or a bed of powders.

8. Method according to any one of claims 1 to 7, characterized in that the layer of inorganic precursors (11) is formed by thermal evaporation or spin coating.

9. Method according to any one of claims 1 to 7, characterized in that the layer of inorganic precursors (11) is formed by short-distance sublimation.

10. A method according to any one of the preceding claims, characterized in that the substrate (10) is a glass, plastic, metal or silicon substrate, preferably a textured silicon substrate.

11. A method of manufacturing a single-junction perovskite photovoltaic cell or a multi-junction perovskite photovoltaic cell comprising at least one perovskite photovoltaic cell, for example a perovskite-silicon tandem photovoltaic cell, a perovskite-perovskite tandem photovoltaic cell, a perovskite-perovskite-silicon triple-junction photovoltaic cell or a perovskite-perovskite-perovskite triple-junction photovoltaic cell, the method comprising providing an organic-inorganic perovskite layer according to the method according to any one of claims 1 to 10.

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