Process for producing a hybrid organic-inorganic perovskite layer

Abstract

Process for the preparation of an organic-inorganic hybrid perovskite layer. This description relates to a process for the preparation of an organic-inorganic hybrid perovskite layer comprising the following steps: Formation of a layer (11) comprising the inorganic precursors of the perovskite material on a substrate (10) by CSS or CSVTD; Implementation of a CSS or CSVTD step from organic precursors (22, 24), whereby the organic precursors (22, 24) react with the layer (11) of inorganic precursors and a layer (12) of organic-inorganic hybrid perovskite material is obtained. Figure for the abstract: Fig. 6

Description

Title of the invention: Method for producing an organic-inorganic hybrid perovskite layer 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 field of photovoltaics, 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, compatible with large-scale implementation. Prior art

[0004] Organic-inorganic hybrid perovskites are particularly interesting materials for photovoltaic cells, and in particular for tandem photovoltaic cells on silicon.

[0005] 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.

[0006] Generally, the processes for developing hybrid perovskite layers are carried out in two stages: the inorganic part of the perovskite is deposited first and then the organic part is added.

[0007] For example, in the article by Zhang et al. (ACS Appl. Energy Mater. 2022, 5, 5797-5803) films of Cso.i4FAo.86Pb(BrxIi_x)3 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 film of FAI or an organic film of FAFFABr is prepared by depositing the organic precursors on a substrate by spraying an ethanol solution comprising said precursors. This film is used to implement a close space sublimation (or 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] However, the described synthesis process requires a first step of depositing the inorganic precursors which is generally done by liquid means or by coevaporation. In these 2 cases, the method of depositing the inorganic precursors poses serious obstacles for industrialization, in particular with regard to production rates, homogeneity of deposition over large surfaces, the possibility of deposition on textured substrates, or even the management of liquid effluents. Summary of the invention

[0009] There is a need to obtain a method for forming a layer of organic-inorganic hybrid perovskite whose composition is controlled and for forming such a layer, on large surfaces (typically greater than 20x 20 cm2) and / or on textured substrates (for example for plates, in particular made of silicon, having on the surface a texture of pyramids having, in particular, a height greater than 1 pm) with a high rate so as to be able to be industrialized.

[0010] This aim is achieved by a method for producing a layer of organic-inorganic hybrid perovskite material comprising the following steps: a) Formation of a layer comprising the inorganic precursors of the perovskite material on a substrate by CSS or by CSVTD, b) Implementation of a CSS or CSVTD step from organic precursors, whereby the organic precursors react with the inorganic precursors present in the layer and a layer of organic-inorganic hybrid perovskite material is obtained.

[0011] The invention is fundamentally distinguished from the prior art by the implementation of a two-step production process, where step a) and step b) can be independently implemented by close-spaced sublimation (CSS) or by close-spaced vapor transport deposition (CSVTD), also sometimes referred to as CSVT. CSVTD is also sometimes referred to as short-range chemical vapor transport.

[0012] The CSS step consists of sublimating a solid material, the distance between the substrate and the material to be sublimated being small. By small distance is meant a distance of between 0.1 and 10 mm, preferably between 0.1 and 5 mm.

[0013] The CSVTD step consists of sublimating a solid material or evaporating a liquid material. The solid or liquid material is, for example, positioned in a crucible which is heated. This step is also carried out at a short distance (for example, of the order of a millimeter).

[0014] The CSVTD allows, just like the CSS, to have a high deposition speed, a low material loss and high layer homogeneity.

[0015] The first step (step a) by CSS or CSVTD makes it possible to form a layer comprising the inorganic precursors of the perovskite material. The second step (step b) by CSS or CSVTD makes it possible to impregnate the previously deposited layer with the organic precursors of the perovskite material. This impregnation results from the reaction of the inorganic precursors with the gaseous phase resulting from the evaporation or sublimation of the organic precursors. During step b), the organic precursors are in gaseous form. This impregnation leads to the formation of the final material.

[0016] These sublimation or evaporation methods are particularly interesting from an industrial point of view because they allow the rapid formation of layers of perovskite material of controlled composition.

[0017] For example, CSS and CSVTD deposition rates can be greater than 100 nm / min or even greater than 1000 nm / min. For illustration, evaporation deposition rates are of the order of 10 nm / min.

[0018] Advantageously, the organic-inorganic hybrid perovskite has the formula A' [ x AxBX3 with:

[0019] A' an inorganic cation or an alloy of inorganic cations, preferably chosen from Cs, Rb, K and Na,

[0020] A monovalent organic cation or an alloy of monovalent organic cations, preferably chosen from methylammonium (MA), formamidinium (FA), guanidinium (GA), dimethylammonium (DA) and Timidazolium (IA), even more preferably A corresponds to MA and / or FA,

[0021] B an inorganic cation or an alloy of inorganic cations, preferably chosen from Pb, Sn and Ge,

[0022] X one or more halogens, preferably chosen from Cl, Br, I and F.

[0023] Advantageously, the organic-inorganic hybrid perovskite has the formula Csbx MAxPb(Ij yBry)3, Csj xFAxPb(Ij y zBryClz)3or Csj xFAxPb(Ij yBry)3, Cs1.xFAxPbo.5Sno.5(Ii-y Bry)3, Csi x zMAxFAzPb(Ii yBry)3 orCskx_zMAxFAzPbkkSnkIi_yBry)3with 0 <y<l,0<k <l,0<x<l,0<z<let0< x+z < 1, et de préférence 0<y<let0<x<l.

[0024] Advantageously, the layer comprising the inorganic precursors is a layer containing Pb, Cs and one or more halogens chosen from iodine, bromine and chlorine. Advantageously, the layer of inorganic precursors is a layer of Pbl 2 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 CSI, a layer of Pbl2, PBBr2 and CSBr, a layer of Pbl2, CSI and CsBr, a layer of PbBr2, CSI and CsBr or a layer of PbBr2, Pbl2, CSI and CsBr.

[0025] Advantageously, the organic precursors are FA(Ii yBry) or MA(L yBry) with 0 < y < 1 and, preferably, 0 < y < 1.

[0026] According to a first advantageous embodiment variant, step a) and step b) are carried out by CSS.

[0027] According to this first advantageous embodiment variant, step a) and / or step b) can be carried out by CSS from a precursor powder obtained by mechanical synthesis.

[0028] For example, step b) can be carried out by CSS from an organic precursor powder, the organic precursor powder is obtained by mechanical synthesis by co-grinding at least a first group of particles in a first material and a second group of particles in a second material, until a third group of particles in a third material is formed, the third group of particles forming the organic precursor powder.

[0029] Step a) can also be carried out in this way by mechanosynthesis by co-grinding different groups of particles made of different materials to obtain the powder of inorganic precursors, formed of particles, preferably single-phase, each particle having the composition that it is desired to subsequently react with the organic precursors.

[0030] According to a second advantageous embodiment variant, step a) and step b) are carried out by CSVTD.

[0031] Advantageously, the substrate is a substrate suitable for the photovoltaic field. For example, it may be a glass, plastic or metal substrate.

[0032] Advantageously, the substrate is a silicon substrate, preferably a textured silicon substrate. Such a substrate is particularly interesting for forming a photovoltaic device.

[0033] 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.

[0034] 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 perovskite-perovskite-perovskite triple junction photovoltaic cell. Brief description of the drawings

[0035] These and other features and advantages will be set forth in detail in the following description of particular embodiments given without limitation in relation with the attached figures among which:

[0036] [Fig.lA] and [Fig.lB] schematically represent different stages of a method for producing an inorganic organic perovskite layer according to a particular embodiment of the invention;

[0037] [Fig.2A] and [Fig.2B] schematically represent different stages of a method for producing an inorganic organic perovskite layer according to another particular embodiment of the invention;

[0038] [Fig. 3] schematically represents in section a short-distance sublimation oven according to a particular embodiment of the invention;

[0039] [Fig.4A] and [Fig.4B] 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;

[0040] [Fig.5A] is a photograph obtained using a scanning electron microscope of a layer of inorganic precursors obtained according to a particular embodiment of the invention;

[0041] [Fig.5B] is a photograph obtained using a scanning electron microscope of a layer of organic-inorganic hybrid perovskite obtained from the layer of inorganic precursors of [Fig.4A], according to a particular embodiment of the invention;

[0042] [Fig.6] is a graph representing an X-ray diffractogram of an organic-inorganic perovskite layer, according to a particular embodiment of the invention;

[0043] [Fig.7] is a photograph obtained using a scanning electron microscope of a layer of perovskite deposited on a textured silicon substrate, according to a particular embodiment of the invention;

[0044] [Fig.8] is a current-voltage curve, under AMI,5 illumination at t=0 and at t=24h and in the dark, of a photovoltaic cell comprising a layer of organic-inorganic perovskite obtained according to a particular embodiment of the invention;

[0045] [Fig.9] is a current-voltage curve under AM 1.5 illumination of a photovoltaic cell comprising an organic-inorganic perovskite layer obtained according to another particular embodiment of the invention. Description of the embodiments

[0046] 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.

[0047] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been shown and are detailed.

[0048] Unless otherwise specified, when referring to two elements connected to each other, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") to each other, this means that these two elements can be connected or be connected by means of one or more other elements.

[0049] 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.

[0050] Unless otherwise specified, the expressions "about", "approximately", "substantially", and "of the order of" mean to within 10%, preferably to within 5%.

[0051] The process that we will subsequently describe in more detail, with reference to Figures 1A and 1B as well as to Figures 2A and 2B, concerns the production of a layer of organic-inorganic hybrid perovskite.

[0052] 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 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 Pb2+, Sn2+ and Ge2+, X a halogen anion or alloy of halogen anions, preferably chosen from Cl, Br, I and F.

[0053] Preferably, A' represents Cs.

[0054] Preferably, A represents MA and / or FA.

[0055] Preferably, B represents Pb, Sn and Ge,

[0056] Preferably, X represents Br and / or I.

[0057] Advantageously, the organic-inorganic hybrid perovskite has the formula Cs, x MAxPb(L yBry)3, Csj xFAxPb(Ij y zBryClz)3 or Csj xFAxPb(L yBry)3 or Csj xFAxPb(L yBry)3 or Csj xFAxPbo.xSnoAI i yBry)3 or Csi x zMAxFAzPb(Ii yBry)3 or Cskx_zMAxFAzPbi_kSnkIiyBry)3 with 0 < y < 1.0 <k<l,0<x<l,0<z<let0< x+z < 1, et de préférence 0<y<let0<x<l.

[0058] The method comprises the following steps: a) Formation of a layer 11 on a substrate 10, by CSS or CSVTD, by sublimating or evaporating the inorganic precursors 21, 23 of the perovskite material, whereby a layer 11 is formed comprising, and preferably consisting of, the inorganic precursors (figures 1A or 2A), b) Sublimation or evaporation, by CSS or CSVTD, of organic precursors 22, 24 of the perovskite material, whereby the organic precursors, in gaseous form, react with the inorganic precursors present in the layer 11 formed in step a) and a layer 12 of organic-in-organic hybrid perovskite material is obtained (figures 2A or 2B).

[0059] It is possible to implement one of the four embodiment variants:

[0060] - implementation of step a) by CSS and implementation of step b) by CSVTD,

[0061] - implementation of step a) by CSS and implementation of step b) by CSS,

[0062] - implementation of step a) by CSVTD and implementation of step b) by CSS,

[0063] - implementation of step a) by CSVTD and implementation of step b) by CSVTD.

[0064] According to a particularly advantageous variant, step a) and step b) are implemented by CSS (figures 1A and 1B).

[0065] In the case of deposition by CSS, the precursors 21, 22 are in the solid state, preferably in the form of a powder.

[0066] The powder can form a bed of particles.

[0067] Alternatively, the particles can be agglomerated to form a solid target (also called a wafer). The powder can be compacted, for example, by means of a hydraulic press. For this, the powder is pressed, for example, with a hydraulic press with P ~ IxlO7 Pa). The pressing of the target can be done by heating the powder.

[0068] The precursor powder 21, 22 used may comprise, for example, a first group of particles made of a first material and a second group of particles made of a second material.

[0069] According to an advantageous embodiment, the precursor powder 21, 22 is obtained by mechanosynthesis, by co-grinding at least a first group of particles in a first material and a second group of particles in a second material, until a third group of particles in a third material is formed.

[0070] The third group of particles forms the inorganic precursor powder 21 (step a)) or the organic precursor powder 22 (step b)).

[0071] Mechanosynthesis consists of carrying out a very energetic co-grinding of pure or pre-alloyed materials in a high-energy mill until a powder is obtained whose particles are single-phase or polyphase. Preferably the particles are single-phase.

[0072] Co-grinding is carried out with at least two groups of particles. It could also be implemented with more than two particle groups (e.g. three or four particle groups).

[0073] 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.

[0074] The grinding rotation speed is high (typically from 100 rpm to 700 rpm, for example 500 rpm). It depends on the mill 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.

[0075] The mixture may be an equimolar mixture.

[0076] This embodiment is particularly advantageous because it makes it possible to directly have the correct composition and the correct phase of the material to be sublimated.

[0077] According to another embodiment variant, to implement step a) and / or step b) by CSS, the precursors may be in the form of a layer previously deposited on another substrate. Such a layer may be, for example, formed by a vacuum deposition method (evaporation or sputtering in particular) or by a liquid deposition method (for example by spin coating, or by slot-die deposition). It is also possible to form a single crystal of the material to be deposited (wafer, cut ingot, etc.).

[0078] During step a) by CSS, the transfer of material between the precursors 21 and the substrate 10 takes place over a very short distance (between 0.1 and 10 mm, advantageously 5 mm). The precursors 21 are advantageously arranged so as to have the same geometric shape and the same surface area as the substrate 10 on which it is desired to deposit the precursors. Thus, the inorganic precursors 21 sublime and are deposited on the substrate 10 (arrow in [Fig. 1A]).

[0079] During step b) by CSS, the precursors pass from a solid state to a gaseous state (represented by arrows in [Fig.lB]). The precursors 22 can therefore be shaped in a form which may be identical to or different from that of the substrate 10 covered by the layer 11 of inorganic precursors.

[0080] During step b) by CSS, only the composition of the target is important. Advantageously, the composition of the target can be identical to the composition of the gas phase that one wishes to react with the layer of inorganic precursors (case of a single-phase target).

[0081] Steps a) and b) of CSS can be carried out in a short-distance sublimation oven.

[0082] A lamp oven can be used to carry out these steps.

[0083] For example, as shown in Figures 1A, 1B and in particular detail in [Fig.3], the CSS 100 furnace comprises a reactor 102 around which a heating system is positioned. For example, it may be lamps 104 or any other heating system (resistance, induction for example).

[0084] The reactor 102 can be made of quartz, graphite, or metal.

[0085] The reactor 102 may be tubular.

[0086] The furnace 100 also comprises 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, capable of withstanding pressure, vacuum and high temperatures. They are preferably made of graphite.

[0087] The substrate 10 and the precursors 21, 22 are positioned between the susceptor 106 and the cover 108.

[0088] Preferably, the substrate 10 is in direct contact with the cover 108 which maintains its temperature at the set value.

[0089] The precursors 21, 22 are arranged on the susceptor 106.

[0090] The substrate 10 is at a short distance from the precursors 21, 22. By short distance, we mean a distance typically of 0.05 mm to 20 mm, or even of 0.1 to 20 mm, preferably of 1 mm to 7 mm, for example of 1 mm to 5 mm or of 3 mm to 5 mm for step a) and preferably of 0.1 mm to 5 mm for step b). In particular, a distance of 1 mm or 5 mm may be chosen. A compromise will be chosen between a distance close enough to have a high deposition speed and a distance sufficient to be able to maximize and maintain the thermal gradient during deposition.

[0091] 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.

[0092] The cover 108 can be held pressed against the substrate 10 by a closure system in the susceptor 106 not shown (for example a screw or any other fixing system).

[0093] The susceptor 106 and the cover 108 each have a thermocouple 114 or any other system (pyrometer, etc.) to measure and control their temperature.

[0094] A heating system (lamp, resistors, induction, etc.) makes it possible to regulate the temperature of the susceptor 106 (Ttarget) and the cover 108 (Tsubstrate) in a range that can go from 20°C to 600°C. Temperature increase 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.

[0095] It is possible to add specific cooling devices for the cover 108 (for example, integrated piping for coolant, protective screen against radiation of the susceptor, radiators.

[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] Sublimation deposition is carried out by heating the susceptor 106 and the cover 108 under vacuum (typically between 0.01 and 100 Pa, for example 1 Pa), so as to sublimate the organic or inorganic precursors.

[0100] In the case of step a) of CSS deposition, the temperature of the substrate Tsub is lower than the temperature of the target Tcible in order to create a thermal gradient. The substrate is advantageously maintained at a controlled temperature. The same applies to the target.

[0101] In the case of step a) of deposition by CSS, the temperature difference Ttarget -Tsub is from 10°C to 350°C, preferably from 50°C to 300°C and even more preferably from 50°C to 200°C, for example 100°C.

[0102] During step b), the temperature of the target may be identical to the temperature of the substrate.

[0103] 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.

[0104] 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.

[0105] The target temperatures depend on the material to be sublimated.

[0106] For example, temperature rise ramps of between 0.2°C / s and 10°C / s, for example 1°C / s, can be carried out.

[0107] According to another particularly advantageous variant, step a) and step b) are implemented by CSVTD (figures 2A and 2B).

[0108] As shown in Figures 2A and 2B, in the case of a step by CSVTD, the precursors 23, 24 can be positioned in a crucible 25. The substrate 10 is positioned opposite the crucible 25. It is also possible to scroll the substrate 10 relative to the crucible 25.

[0109] The use of crucibles makes it possible to consider heating the inorganic precursors or the organic precursors up to their melting temperature or even beyond their melting temperature to accelerate the material flows (deposition rate of the inorganic precursors or partial pressure of the organic part).

[0110] The CSVTD reactor is, for example, a quartz tube. The heating system can be equipped with lamps 104, or even with heating resistors.

[0111] The substrate 10 and the crucible 25 can be heated independently of each other by lamps or any other heating system (resistance for example).

[0112] The precursors 23, 24 may be in the liquid state or in the solid state. Thus, depending on the state of the precursor (liquid or solid), the CSVTD step may be carried out by evaporation or by sublimation, respectively.

[0113] When the precursors are in the solid state, they can be in the form of powders obtained by mechanosynthesis.

[0114] The implementation of a CSVTD makes it possible either to form a layer 11 on the substrate 10 from the inorganic precursors 23 (step a)) or to react the vapors of the organic precursors 24 with the layer 11 of inorganic precursors to form the perovskite layer 12 (step b)).

[0115] The temperature of the substrate Tsub used in the process (i.e. during step a) and / or during step b)) are advantageously less than 250°C and even more advantageously less than 200°C.

[0116] In the various embodiments described above, the deposition chamber used for step a) and the deposition chamber used for step b) may be identical or different.

[0117] Advantageously, different chambers are used and the method is carried out continuously by implementing step a) in a first chamber and step b) in a second chamber.

[0118] The implementation of the step by CSS or by CSVTD allows the substrate to move from one chamber to another to be in successive contact with the inorganic precursors then with the organic precursors.

[0119] The nature of the substrate is closely linked to the intended application. The substrate 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.

[0120] Advantageously, the substrate is functionalized with a layer or a stack of insulating, conductive and / or semiconducting layers to inject and / or collect charges in the perovskite material.

[0121] The layers obtained by such a process are homogeneous and continuous.

[0122] Preferably, the inorganic precursors 21, 23 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 than three precursors.

[0123] For example, the inorganic precursors 21, 23 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 PbBr2, Pbl2, CSI and CsBr. Preferably, these are Pbl2 and CsBr.

[0124] For example, the organic precursors 22, 24 are FA(Ii yBry) or MA(Ii yBry) with 0 < y < 1. Such precursors can be obtained, for example, by mechanosynthesis from FABr and FAI powders or from MABr and MAI powders. The organic precursors MA(L yBry) can be used to form layers of Csi_x MAxPb(Ii yBry)3. The organic precursors FA(Ii yBry) can be used to form layers 12 of Csi xFAxPb(Ii yBry)3.

[0125] According to another example, the organic precursors 22, 24 can be MAzFAi.zIi.y Bry (with 0 <z<l et 0<y<l). Ils peuvent être obtenus par mécanosynthèse à partir de poudres de MABr et / ou MAI et / ou FABr et / ou FAI. Ces précurseurs peuvent être utilisés pour former des couches 12 de CsxMAzFAi z xPb(Ii yBry)3.

[0126] According to another example, the organic precursors 22, 24 are FAIi y zBryClz (with 0 <y<l et 0<z<l). Ils peuvent être obtenus à partir de poudres de FAI et / ou FABr et / ou FAQ. Ils peuvent servir à former des couches 12 de Csi xFAxPb(Ii y zBryClz)3

[0127] 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.

[0128] In particular, the method is applicable to depositing organic-inorganic hybrid perovskites of low thickness (between 10 nm and 5000 nm). These materials are generally used for visible or near infrared optical applications. Examples include photovoltaic applications, but also infrared and near infrared detection or light emission in wavelengths visible, near infrared and infrared waves.

[0129] In particular, with regard to photovoltaic applications, the method previously described can be used to produce a layer of organic-inorganic hybrid perovskite material in a photovoltaic cell.

[0130] By varying the amount of iodine, bromine and chlorine in the perovskite material, it is possible to modify the band gap energy.

[0131] Photovoltaic cells can be single junction cells or multi-junction cells.

[0132] For example, a single junction photovoltaic cell of the pin type may comprise from the rear face to the front face ([Fig.4A]): - 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 270 substrate.

[0133] Preferably, the photovoltaic cell is made up of the different elements mentioned above.

[0134] The front face of the photovoltaic cell is intended to receive a luminous flux.

[0135] The incident radiation is represented by arrows in [Fig.4A].

[0136] The upper electrode 210 is, for example, made of Ag, Cu, Ni, Al. It has, for example, a thickness of between 50 and 300 nm.

[0137] The buffer layer 220 has a thickness of between 1 nm and 5 nm, preferably between 3 and 4 nm. It is advantageously continuous and conformal. It is in direct contact with the n-type layer.

[0138] It can be a layer of LiF, SnS, metal oxide, BCP (bathocuproine) or even alumina of formula A12O3 or formula AIOx with x between 0.8 and 1.5.

[0139] The n 230 type layer may be, for example, made of 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 made of C60. The n 230 type layer has, for example, a thickness of between 5 and 50 nm.

[0140] 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.

[0141] Such layers have a thickness between 5 and 30 nm.

[0142] The active layer 240 is a perovskite active layer obtained by the pre-process previously described. Preferably the perovskite layer is a perovskite of type APbX3 with A representing methylammonium, dimethylammonium, formamidinium, guanidinium or cesium cations (the aforementioned cations can be used alone or in a mixture) and X representing halide anions (preferably chlorine, bromine, iodine anions alone or in a mixture).

[0143] The active layer 240 has, for example, a thickness of between 200 nm and 1.5 pm.

[0144] 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). It can have a thickness between 5 and 50 nm.

[0145] 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 (phosphonic 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 (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. Additives can also be added. The molecules of the SAM layer advantageously have a function allowing them to anchor themselves on the underlying oxide layer. Such a p 250 type layer can have a thickness between 1 and 5 nm.

[0146] According to a third variant, the p-type layer 250 is an oxide layer, for example a MoOx layer (having for example a thickness between 5 and 30 nm), a NiOx layer (having for example a thickness between 1 and 30 nm).

[0147] According to another variant, the p-type layer 250 may be an oxide / SAM bilayer, for example a NiOx / SAM bilayer.

[0148] The transparent conductive oxide layer 260 has, for example, a thickness of between 50 and 300 nm. Preferably, it is indium-tin oxide (or ITO).

[0149] These different elements are positioned on a substrate 270 arranged on the rear face. The substrate 270 is, for example, made of glass.

[0150] For example, the photovoltaic cell comprises from the rear face to the front face: - a 210 silver upper electrode, - a buffer layer of alumina 220, - a layer of type n 230 in C60, - an active layer 240 in FAo.83Cso.i7)Pb(Io.6Bro.4)3, - a layer of type n 250 in 2PACz, - a layer of transparent conductive oxide 260 in ITO, - a substrate, preferably in glass 270.

[0151] For example, a tandem photovoltaic cell may include a lower Silicon (Si) sub-cell and an upper Perovskite (PK) sub-cell.

[0152] Such a cell is for example shown in [Fig.4B]. 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 in 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 in BCP or in oxide such as SnOx, - a third layer of transparent conductive oxide 326, for example in ITO or AZO, - a second electrode 328, for example made of Ag, Cu, Ni or Al.

[0153] 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.

[0154] 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).

[0155] For photovoltaic applications, the process of developing a pe- rovskite can also be used to make perovskite-based single-junction solar cells. 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.

[0156] It is also possible to fabricate a perovskite (1.2 eV) / perovskite (1.8 eV) tandem cell by depositing a first perovskite in Csi_xFAxPbo.5Sno.5(Ii_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.

[0157] 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.

[0158] 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.

[0159] Illustrative and non-limiting example of a particular embodiment of the invention

[0160] In this example, an organic-inorganic hybrid perovskite layer of formula CsxFAi xPb(Ii yBry)3 with x~0.8 and y~0.2 was grown. The layer has a thickness of 300 nm.

[0161] Preparation of the first target for the first CCS deposition step and deposition of the inorganic precursors from this first target

[0162] The first target is manufactured from precursors of Pb and Cs. In particular, the precursors are halides of Pb and Cs, chosen from, on the one hand, Pbl2 and PbBr2, and, on the other hand, Csl and CsBr.

[0163] The powder is compacted using a hydraulic press (P ~ IxlO7 Pa). It forms a solid wafer with lateral dimensions identical to those of the deposit that we want to make. It has a thickness of approximately 0.5 mm. The mass of the powder to make the target is calculated from its dimensions, the density of the powder and the compactness of the wafer (approximately 0.8 for this pressure value).

[0164] For example, for a 3 cm2 Pbl2+ 40at% CsBr target, approximately 0.4 g of powder will be used.

[0165] It is also possible to obtain a powder formed from particles, made of the same material, by co-grinding the Pbl2 and the CsBr. This produces a very homogeneous mixture. This step is optional.

[0166] For example, the powder can be manufactured by co-grinding in a planetary mill for 1 h at 500 revolutions / min (rpm) under a neutral atmosphere (Ar or N2) the Pbl2 with 40 at% CsBr. This grinding is carried out in a tungsten carbide bowl with tungsten carbide balls and a powder / balls mass ratio < 0.2.

[0167] The deposition of the inorganic precursors is carried out by CSS from the first target.

[0168] CSS deposition can be carried out in an annealing furnace in which the substrate on which the deposition is to be made is placed opposite the target of the material that is to be deposited.

[0169] The substrate here is a silicon heterojunction solar cell which has a textured surface covered with an ITO electrode and a SAM (“Self-Assembled Monolayer”) type charge injection layer.

[0170] The substrate is placed at a short distance from the target. Typically, a short distance is a distance between 0.1 and 10 mm. For example, a distance of about 5 mm is chosen.

[0171] The assembly is under vacuum, typically the pressure can be between 0.01 Pa and 100 Pa. For example, the pressure is 1 Pa.

[0172] A heating system allows the target and the substrate to be heated independently. The target is heated to a temperature sufficient for it to sublime and below its melting temperature. The substrate is heated to a temperature lower than that of the target (10°C to 300°C lower, typically 100°C lower).

[0173] The heating system is provided by a susceptor and a graphite cover against which the target and the substrate are pressed respectively to ensure their thermalization. The heating system chosen is a lamp system. Any other heating system (resistive heating, induction) for heating a susceptor / cover system made of thermally conductive material (graphite or other) or a system directly heating the target and substrate by controlling their temperature is possible.

[0174] The target material sublimes and condenses on the substrate.

[0175] The deposition time and temperatures determine the thickness of the deposit.

[0176] The thickness of the final perovskite is a function of the thickness of the layer of inorganic precursors deposited by CSS.

[0177] For example, to synthesize a perovskite layer having a thickness of 300 nm, a layer of inorganic precursors (from a target of Pbl2 + 40 at% CsBr) of about 250 nm can be deposited ([Fig.5A]). The target can be, for example, heated to 270°C and the substrate to 170°C for a period of 5 min.

[0178] The target substrate distance is 5 mm and the pressure is 1 Pa.

[0179] Preparation of the second target for the second deposition step by CCS and formation of the perovskite layer from this second target.

[0180] This second deposit will make it possible to transform the inorganic precursors into pe- rovskite. The second target for CSS deposition therefore brings the organic elements of perovskite. Here, it is FA (CH5N2) or MA (CH3NH3).

[0181] The second target comprises FA halides. The target is a solid target, obtained from a compacted powder of FAI 50at% + FABr 50 at%. The conditions for manufacturing the second solid target are identical to those used for manufacturing the first target.

[0182] The type of CSS equipment used is the same as that used for the first deposition. The substrate comprising the inorganic precursors is positioned opposite and at a short distance and under vacuum from the CSS target.

[0183] This step is not a deposition step: it is not a matter of transferring material from the target to the substrate, but rather it is a step of annealing the precursors present on the substrate under an atmosphere generated by the sublimation of the second target. Consequently, the target and the substrate can be maintained at the same temperature or at different temperatures.

[0184] For a given temperature, the duration of this step is adjusted so that all the precursors present on the substrate have reacted. Care should be taken not to exceed this duration at the risk of degrading the perovskite (over-reaction).

[0185] For example, for a 250 nm precursor layer containing PbI2 and 40 at% CsBr, and a solid target comprising 50 at% FAI and 50 at% FABr, the target and the substrate are heated to 140°C for a duration of 15 min for a target-substrate distance of 5 mm and under a pressure of 1 Pa. The perovskite layer obtained is shown in [Fig.5B].

[0186] The perovskite layer was characterized by X-ray diffraction ([Fig.6]). The perovskite layer corresponds well to the material Csi xFAxPb(Ii yBry)3 with x~0.9 and y~0.2.

[0187] A sectional observation ([Fig.7]) confirms that, even for a textured substrate, the layer obtained is conformal and continuous.

[0188] The obtained photovoltaic cell was tested by means of a current-voltage curve in the dark under AMI illumination,5 at t=0 and at t=24h ([Fig.8]). The photovoltaic cell comprising a perovskite layer obtained with such a process has good properties.

[0189] The influence of the presence of a MgFx passivation layer and thermal annealing at 150°C for 20 min in air in a single junction cell was also studied ([Fig.9]). The organic-inorganic perovskite layer is produced using the two-step process previously described (curve denoted CSS + annealing). The resulting photovoltaic cell exhibits very good performance. These performances are comparable to those obtained for a photovoltaic cell comprising an organic-inorganic perovskite layer prepared by spin coating (curve 'spin coating'). The spin coating technique is a deposition technique that is difficult to industrialize for such applications. Its replacement by successive CSS / CSVTD deposits is therefore particularly interesting.

Claims

Claims

1. A method for preparing a layer of organic-inorganic hybrid perovskite material comprising the following steps: a. Forming a layer (11) comprising the inorganic precursors of the perovskite material on a substrate (10) by CSS or CSVTD, b. Carrying out a CSS or CSVTD step from organic precursors (22, 24), whereby the organic precursors (22, 24) react with the layer (11) of inorganic precursors and a layer (12) of organic-inorganic hybrid perovskite material is obtained.

2. Method according to claim 1, characterized in that the organic-inorganic hybrid perovskite has the formula A' kxAxBX3 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 organic-inorganic hybrid perovskite has the formula Csi xMAxPb(I i yBry)3, Csi xFAxPb(Ii y zBryClz)3jCsj xFAxPb(Ii y Bry)3j Csi.xFAxPbo.5Sno.5(I i y Bry)3, Csj x zMAxFAzPb(Ij y Bry)3 orCsj x zMAxFAzPbj kSnkIj y Bry)3with 0 <y<l,0<k<l,0<x<l,0<z<let0< x+z < 1.

4. 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.

5. Process according to any one of the preceding claims, characterized in that the organic precursors are FA(Ii yBry) or MA(I । yBry) with 0 < y < 1.

6. Method according to any one of claims 1 to 5, characterized in that step a) and step b) are carried out by CSS.

7. Method according to any one of claims 1 to 6, characterized in that step b) is carried out by CSS from an organic precursor powder (22), the organic precursor powder (22) 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 (22).

8. Method according to any one of claims 1 to 5, characterized in that step a) and step b) are carried out by CSVTD.

9. 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.

10. 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 9.

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