Method for manufacturing an optoelectronic device

Abstract

Method for manufacturing an optoelectronic device The present description relates to an optoelectronic device (100) comprising an active layer of perovskite (140), the active layer of perovskite (140) being doped with samarium, from a first face, over a part (141) of its thickness, a buffer layer (150), for example of PCB or oxide, being in direct contact with the doped part (141) of the active layer of perovskite (140), the perovskite having the formula ABX3 with A representing one or more cations, preferably chosen from methylammonium, formamidinium and cesium, B representing lead, tin or a mixture thereof, X representing one or more anions, preferably chosen from chlorine, bromine, iodine and mixtures thereof. Doping can be achieved by depositing on the first face of the active layer in perovskite (140) a solution containing samarium, preferably by spinning deposition in dynamic mode.Figure for the summary: Fig. 2A.

Description

Title of the invention: Method for manufacturing an optoelectronic device. Technical field.

[0001] This description relates generally to the field of optoelectronic devices, and more particularly to optoelectronic devices comprising a perovskite layer, in particular single junction photovoltaic cells or silicon / perovskite tandem photovoltaic cells. Previous technique

[0002] There are several types of perovskite-based photovoltaic cells.

[0003] For example, [Fig.1A] represents a single junction pin-type photovoltaic cell 10 comprising from the face exposed to light radiation: a substrate 11, a transparent conductive oxide layer 12, a hole transport layer 13, a perovskite active layer 14, an electron transport layer 17, a buffer layer 15 and electrodes 16.

[0004] For example, [Fig. 1B] represents a tandem photovoltaic cell comprising a perovskite-based subcell 10 and a silicon-based subcell. The cell comprises, from the face exposed to light radiation: electrodes 16, a transparent conductive oxide layer 12, a buffer layer 15, an electron transport layer 17, a perovskite active layer 14, a hole transport layer 13, an intermediate layer between the two subcells of transparent conductive oxide 20, an n-doped amorphous silicon layer 31, an intrinsic amorphous silicon-based layer 32 serving as a passivation layer, an n-doped crystalline silicon substrate 33, an intrinsic amorphous silicon-based layer 34 serving as a passivation layer, a p-doped amorphous silicon layer 35, an electrode 36, preferably transparent.

[0005] For example, [Fig.1C] represents a single junction nip-type photovoltaic cell 10 comprising from the face exposed to light radiation: a substrate 11, a transparent conductive oxide layer 12, a buffer layer 15, an electron transport layer 17, a perovskite active layer 14, a hole transport layer 13, and electrodes 16.

[0006] These cells comprise an electron transport layer (ETL) located between the perovskite layer and an electrode. The ETL allows the electrons generated by the perovskite layer to be separated, extracted, and transported to the electrode.

[0007] The ETL layer is often formed of a bilayer comprising an n-type extraction layer and an n-type buffer layer. The buffer layer increases the performance of the cell by limiting charge recombination at the interfaces between the perovskite and the upper electrode.

[0008] The buffer layer can be made of BCP, LiF, or transparent metal oxide, for example SnO2.

[0009] The n-type layer is, for example, based on fullerene (C60). C60 is a very common n-type semiconductor in the field of photovoltaics.

[0010] However, the use of C60 creates problems of cell stability (in light and temperature) and charge recombination at the perovskite / C60 interface, which reduces photovoltaic efficiency. Summary of the invention

[0011] There is a need for a manufacturing process for a high-performance and easy-to-manufacture optoelectronic device.

[0012] This goal is achieved by an optoelectronic device comprising an active layer of perovskite, the active layer of perovskite being doped with samarium, from a first face of the active layer of perovskite, over a part of its thickness, a buffer layer, for example of BPC or oxide, being in direct contact with the first face of the active layer of perovskite, the perovskite having the formula ABX3 with A representing an organic or inorganic cation or a combination of one or more organic cations and / or one or more inorganic cations, preferably chosen from methylammonium, formamidinium and cesium, B representing lead, tin or a mixture thereof, X representing one or more anions, in particular one or more halogens, preferably chosen from chlorine, bromine, iodine and a mixture thereof.

[0013] According to a particular embodiment, the perovskite has the formula (Cs,FA) (Sn,Pb)(I,Br)3, preferably (Cs,FA)Pb(I,Br)3.

[0014] According to a particular embodiment, the doped part of the perovskite active layer has a thickness between 50 and 150 nm, preferably between 80 and 120 nm.

[0015] According to a particular embodiment, the optoelectronic device is a single-junction pin-type photovoltaic cell, comprising, for example, from a face subjected to light radiation: - a substrate, - a lower electrode, - a p-type conductive layer, - the samarium-doped perovskite active layer, from the first face of the perovskite active layer, over a portion of its thickness, - a buffer layer in direct contact with the first face of the perovskite active layer, - a top electrode.

[0016] According to a particular embodiment, the optoelectronic device is a pin-type perovskite-on-silicon tandem photovoltaic cell comprising two subcells stacked one on top of the other, a first subcell being a perovskite subcell and a second subcell being a silicon subcell, for example a silicon heterojunction subcell, the first subcell comprising, for example, from a face subjected to light radiation: - an upper electrode, - a transparent conductive oxide layer, - a buffer layer in direct contact with the first face of the perovskite active layer, - the samarium-doped perovskite active layer, from the first face of the perovskite active layer, over a part of its thickness, - a p-type conductive layer.

[0017] According to a particular embodiment, the optoelectronic device is a single junction photovoltaic cell of the nip type, comprising, for example, from a face subjected to light radiation: - a substrate, - a lower electrode, - a buffer layer in direct contact with the first face of the perovskite active layer, - the samarium-doped perovskite active layer, from the first face of the perovskite active layer, over a part of its thickness, - a p-type conductive layer, - an upper electrode.

[0018] This objective is also achieved by a method for manufacturing an optoelectronic device comprising a step in which a perovskite active layer is doped with samarium from a first face of the active layer, over a portion of its thickness, thereby forming an n-type layer in the perovskite active layer, the perovskite having the formula ABX3 with A representing an organic or inorganic cation or a combination of one or more organic cations and / or one or several inorganic cations, preferably chosen from methylammonium, formamidinium and cesium, B representing lead, tin or a mixture thereof, X representing one or more anions, in particular one or more halogens, preferably chosen from chlorine, bromine, iodine and one of their mixtures, a buffer layer, for example in PCB or oxide, being in direct contact with the first face of the active layer in perovskite.

[0019] According to a particular embodiment, samarium doping is obtained by depositing a solution containing samarium, for example Sml2 or Sm(acac)3, on the perovskite active layer.

[0020] According to a particular embodiment, the solution comprises Sml2 and isopropanol.

[0021] According to a particular embodiment, the solution is deposited by rotating tray in dynamic mode according to the following sub-steps: - rotate the structure containing the perovskite active layer in a spinning deposition machine, for example at 3000 rpm. - deposit the solution containing samarium onto the active perovskite layer, while the structure is still rotating, - maintain rotation after the solution has been applied, for example for a period of 30 seconds. - stop the rotation of the structure.

[0022] According to a particular embodiment, the solution has a concentration in Sml2 less than or equal to 2mg / mL, preferably between 0.5mg / mL and 2mg / mL.

[0023] According to a particular embodiment, the optoelectronic device is a pin-type photovoltaic cell, for example a silicon-on-perovskite tandem photovoltaic cell or a single-junction photovoltaic cell. Brief description of the drawings

[0024] These features and advantages, as well as others, will be described in detail in the following description of particular embodiments, given by way of non-limiting example, in relation to the accompanying figures, among which:

[0025] Fig.1A, Fig.1B and Fig.1C, previously described, represent schematically and in cross-section, respectively, a single pin junction perovskite photovoltaic cell, a silicon / pin perovskite tandem photovoltaic cell and a single nip junction perovskite photovoltaic cell, according to the prior art;

[0026] Figures [Fig. 2A], [Fig. 2B], and [Fig. 2C] represent, schematically and in cross-section, respectively, a single-junction perovskite photovoltaic cell pin, a pin silicon / perovskite tandem photovoltaic cell and a nip single junction perovskite photovoltaic cell, according to different particular embodiments of the invention;

[0027] [Fig.3] represents several photographs A), B) and C) obtained by scanning electron microscopy (SEM), respectively, on the one hand, of the surface of a perovskite layer given as a reference (B1), and on the other hand, of the surface of a perovskite layer having received a surface treatment with a composition of Sml2 at 2mg / mL (B.2) and of the surface of a perovskite layer having received a surface treatment with a composition of Sml2 at 10mg / mL (B.3) according to different particular embodiments of the invention;

[0028] [Fig.4] represents several photographs A), B) and C) corresponding to cross-sectional views of the samples observed in [Fig.3];

[0029] [Fig.5A] represents the UV-visible analysis of the samples observed in figures 3 and 4;

[0030] [Fig.5B] represents the data processing to obtain the band gap energy (Eg), from the curves of [Fig.5A];

[0031] [Fig.6] is a graph representing a chemical profile obtained by X-ray diffraction analysis (X-ray diffractometry), giving the crystalline structure of the samples, for the samples observed in Figures 3 and 4;

[0032] [Fig.7] is a graph representing current-voltage (JV) curves, under illumination (AM1.5G) at 25°C, of ​​conventional Si / Pk tandem photovoltaic cells for comparison (A.1 and A.2) and of Si / PK tandem photovoltaic cells according to different particular embodiments of the invention (A.3, A.4, A.5);

[0033] [Fig.8] is a curve obtained by secondary ion mass spectrometry (SIMS) showing the doping of a perovskite layer by samarium, according to another particular embodiment.

[0034] The different elements are not necessarily represented at a uniform scale to make the figures more legible. Description of the implementation methods

[0035] The same elements have been designated by the same reference numerals in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same reference numerals and may have identical structural, dimensional and material properties.

[0036] For the sake of clarity, only the steps and elements useful for understanding the described embodiments have been represented and are detailed.

[0037] Unless otherwise specified, when referring to two interconnected elements, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") to each other, it means that these two elements can be connected or linked through one or more other elements.

[0038] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", etc., or relative position qualifiers, such as the terms "above", "below", "superior", "inferior", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made, unless otherwise specified, to the orientation of the figures.

[0039] Unless otherwise specified, the expressions "approximately", "roughly", and "on the order of" mean at 10%, preferably at 5%.

[0040] By transparency, it is understood that the structure or element in question has a transmittance greater than or equal to 70%, preferably greater than or equal to 80%, and even more preferably greater than or equal to 90%. Transmittance represents the intensity of light passing through the element or structure across the visible spectrum. It can be measured by UV-Vis-IR spectrometry. The transmittance of the visible spectrum corresponds to the transmittance for wavelengths between 350 and 800 nm.

[0041] By between X and Y, it is meant that the bounds X and Y are included.

[0042] The optoelectronic device 100 can be a device selected from: - a photovoltaic device: a single junction solar cell, a tandem configuration solar cell (Silicon / perovskite, perovskite / perovskite, CIGS / perovskite) or, more generally, a multijunction solar cell (SI / PK / PK), - a light sensor further comprising perovskites, quantum dots (e.g. PbS), ILVI (e.g. CdTe), CIGS, thin-film semiconductors, OLEDs, or organic semiconductors, - a light emitter: perovskites, quantum dots (e.g., PbS), ILVI (e.g., CdTe), CIGS, thin-film semiconductors, OLEDs, or organic semiconductors, - a photocatalytic device, - a device for photoelectrolysis.

[0043] Preferably, it is a photovoltaic cell. The photovoltaic cell can be of the nip type or of the pin type (with inverted structure).

[0044] The device comprises at least one active layer 140 made of perovskite material of general formula ABX3 with: A representing an organic or inorganic cation or a combination of inorganic and / or organic cations, B representing lead (Pb), tin (Sn), or a mixture thereof, X representing one or more unions, in particular one or more halogens, more particularly chosen from chlorine, bromine, iodine and one of their mixtures.

[0045] Preferably, the perovskites are organic-inorganic hybrid perovskites. In such perovskite materials, A comprises one or more organic cations that may be associated with one or more metal cations, for example, cesium. The organic cation(s) may be selected from alkylammonium cations (for example, a methylammonium (MA) type cation) and formamidinium (FA) cations.

[0046] The perovskite material is preferably a compound of formula (Cs,FA)(Sn,Pb)X 3, even more preferably (Cs,FA)PbX3 with X being chlorine, bromine, iodine or a mixture thereof. Even more preferably, (Cs,FA)Pb(I,Br)3 is chosen.

[0047] The active layer 140 comprises a first face and a second face. The active layer 140 is doped with samarium over a portion 141 of its thickness from the first face. The doping is carried out at the extreme surface of the perovskite active layer. The active layer is not doped over its entire thickness: it includes an undoped portion 142. Typically, the thickness of the doped portion 141 of the perovskite layer 140 is between 50 and 150 nm, preferably between 80 and 120 nm. Advantageously, it is on the order of 100 nm.

[0048] By partially substituting lead or tin with samarium on the surface of the active layer 140 of the solar cell, a heavily doped n-type perovskite semiconductor layer is formed.

[0049] Indeed, perovskite is a semiconductor material that has a high tolerance to point defects and can be doped. Samarium can be integrated into the perovskite matrix by substituting for lead and / or tin, without changing the crystalline phase of the perovskite.

[0050] The doping of a perovskite layer with europium, and more particularly with samarium, is known [1,2].

[0051] This doping is particularly advantageous in the case of a photovoltaic cell. Indeed, the doped part 141 of the perovskite active layer 140 makes it possible to separate and extract the negative charges created in the active layer 140. It acts as an n-type conducting layer, which makes it possible to do without the use of a conventional electron transport layer (ETL for 'Electron Transport Layer'), for example in C60.

[0052] Here we obtain a photovoltaic cell with a simplified architecture and very good stability.

[0053] The first face of the active layer is in direct contact with a buffer layer 150 (in other words, there are no intermediate layers between the active layer 140 and the buffer layer 150). The second face is in contact with the hole transport layer 130 (also called p-type layer or HTL for 'Hole transport layer').

[0054] For example, the 100 simple pin junction solar cell comprises successively from the face exposed to light radiation represented by the arrows in [Fig.2A]: - a substrate 110, preferably transparent, for example made of glass, - a first electrode 120 called the lower electrode, preferably transparent, for example a layer of transparent conductive oxide (TCO for 'Transparent conductive Oxide'), - a p-type conductive layer 130, for example in a carbazole, - an active perovskite layer 140 having a part doped with samarium 141 and an undoped part 142, - a buffer layer 150, preferably made of BCP or oxide, in contact with the doped part 141 of the active layer 140, - a second electrode 160 called the upper electrode made of metal, for example silver or aluminium.

[0055] Metallic contacts (not shown), for example in Cr / Au, are formed on the substrate 110. They can be offset.

[0056] Illumination occurs through substrate 110.

[0057] The first electrode 120 is preferably made of a TCO (transparent conductive oxide) selected from, for example, ITTO (indium tin oxide or 'Indium Tin Oxide'), AZO (aluminum zinc oxide), IZO (indium zinc oxide) or an oxide selected from ZnO or Al:ZnO. In the case of a TCO, it may have a thickness of between 50 and 500 nm and in the case of an oxide, it may have a thickness of between 20 and 250 nm.

[0058] The p-type material can also be chosen, for example, from sodium poly(styrene sulfonate) (PSS), oxides such as WO3, MoOx (e.g. MoO3), V2O5, NiOx (e.g. NiO), NiOx:Cu, or from pi-conjugated polymers (such as poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3-hexylthiophene) or P3HT and PTAA), or mixtures thereof. It can also be a self-assembled monolayer (SAM) of molecules, for example, a carbazole, specifically chosen from one of the following components: 2PACz ((2-(9H-carbazol-9-yl)ethyl)phosphonic acid), 3PACz, 4PACz, Me-4PACz, MeO-2PACz, MPA, or a derivative with an anchoring function on oxides. The thickness of the p130 layer is between 1 and 50 nm, the thickness being chosen according to the nature of the layer. For example, for SAMs, the thickness of the p130 layer is preferably between 1 and 5 nm whereas for pi-conjugated polymers, it can be between 5 and 50 nm.

[0059] The active layer in perovskite 140 has, for example, a thickness between 200 nm and 1.5 pm.

[0060] The buffer layer 150 can be a BCP layer or an oxide layer, for example chosen from SnOx (with x between 1 and 2), SnOxNy, TiOx, ZnOx. Preferably, the buffer layer 150 is made of SnOx, SnOxNy, or BCP. It has, for example, a thickness of between 1 and 7 nm for BCP and between 5 and 50 nm when it is an oxide layer.

[0061] The upper electrode 160 is, for example, metallic. It can be made of Ag, Cu, Ni, Al. It has, for example, a thickness between 50 and 500 nm.

[0062] The solar cell 100 can be a pin-type perovskite-silicon tandem cell. It is a structure comprising two subcells A, B stacked one on top of the other. The upper subcell A is a perovskite subcell while the lower subcell B is silicon, in particular it is a silicon heterojunction subcell ([Fig.2B]).

[0063] The two subcells A, B can be separated by an intermediate layer 200 that is electronically conductive or semiconductive, and preferably transparent to electromagnetic radiation. It can be made of a TCO (transparent conductive oxide) selected from, for example, ITTO (indium tin oxide), AZO (aluminum zinc oxide), IZO (indium zinc oxide). It has, for example, a thickness of between 5 and 100 nm.

[0064] The perovskite-based subcell A comprises successively, from the upper face exposed to light radiation, represented by arrows in [Fig. 2B]: - a so-called upper electrode, preferably transparent, 160 - a buffer layer 150, preferably made of BCP or oxide, for example SnOxNy, in contact with the doped part 141 of the active layer 140, - an active layer of perovskite 140, part of which 141 is doped with samarium and acts as an ETL, - a p 130 type conductive layer (HTL).

[0065] The silicon heterojunction subcell B comprises, for example, from the intermediate layer 200 or from the perovskite-based subcell: - a layer of n-doped amorphous silicon 310, - preferably a layer of intrinsic amorphous silicon 320 serving as a passivation layer, - a n-doped crystalline silicon substrate 330, - preferably, an intrinsic amorphous silicon-based layer 340 serving as a passivation layer, - a p-doped amorphous silicon layer 350, - an electrode 360, preferably transparent.

[0066] Metallic contacts 370, for example made of silver, are formed on the electrode 360 ​​of the silicon-based subcell, and other metallic contacts can be formed on the upper electrode 160 of the perovskite-based subcell. They can be located on the illuminated side.

[0067] The illumination of a Si / PK 100 tandem device is achieved from the perovskite-based subcell.

[0068] The materials and thicknesses previously described for the single junction perovskite cell can be used for the perovskite-based subcell.

[0069] The solar cells 100 could also be single junction nip type cells or tandem nip type cells.

[0070] Fig. 2C represents, for example, a single-junction nip-type cell 100. The cell comprises, from the upper face exposed to light radiation represented by arrows: - a substrate 110, - a first electrode 120 called the lower electrode, - a buffer layer 150 in direct contact with the first face of the perovskite active layer, - the perovskite active layer 140, a part 141 of whose thickness is doped with samarium, from the first face, - a p-type conductive layer 130, - a second electrode 160 called the upper electrode.

[0071] The materials and thicknesses previously described for the single junction perovskite cell or for the perovskite-based subcell can be used for nip-type cells.

[0072] The devices 100 described exhibit good properties (stability, efficiency) while being easier to manufacture.

[0073] The manufacturing process for such cells includes a step in which a portion 141 of the perovskite active layer 140 is doped with samarium. The doping is carried out from the first face of the active layer 140. After the doping step, the active layer 140 comprises a doped portion 141 acting as an ETL and an undoped portion 142 acting as the active layer.

[0074] It is therefore no longer necessary to deposit an n-type layer (for example in C60), on the perovskite layer of the pin solar cells in single junction or tandem. The manufacturing process for solar cells is made easier because the number of layers to be deposited is reduced.

[0075] In the case of a pin-type structure, the cell manufacturing process may include the following steps: - deposit an active layer of perovskite 140, - doping the perovskite layer 140, from a first face of the active layer 140, so as to form a doped part 141 and an undoped part 142, - deposit the buffer layer 150 on the doped part 141 of the active layer 140.

[0076] Doping can be easily achieved by depositing a solution containing samarium and a solvent onto the active layer 140 in perovskite.

[0077] Samarium is, for example, samarium iodide (Sml2) or samarium acetylacetonate (Sm(acac)3).

[0078] Preferably, the concentration in Sml2 is less than or equal to 2mg / mL. It may be between 0.5 mg / mL and 2 mg / mL.

[0079] Preferably, the solvent is isopropanol (IPA). Such a solvent does not damage the already formed layers of the photovoltaic cell, unlike other solvents such as N,N-dimethylformamide (DMF).

[0080] The solution containing the samarium can be deposited by solvent deposition (liquid chemical deposition), for example by a spin-coating method, also known as dipping, printing, slot-die coating, doctor-blading, inkjet printing, spray pyrolysis, sol-gel deposition, and chemical bath deposition. These liquid deposition methods are easy and quick to implement, while also having a low development cost.

[0081] The deposition is preferably carried out by spin coating.

[0082] Preferably, the spinning deposition is carried out in dynamic mode. The dynamic mode allows the Sm to be introduced only on the surface of the perovskite layer 140.

[0083] By dynamic mode, it is understood that when the solution is deposited on the surface of the perovskite layer 140, the perovskite layer 140 is already rotating. The dynamic mode differs from the static mode in which the perovskite layer is set into rotation after the solution has been deposited on its surface.

[0084] For example, the dynamic mode filing includes the following steps: - position the structure containing the perovskite layer 140 on a tray in a rotary deposition machine; the structure can be held on the tray by suction. - rotate the platter, for example at 3000 rpm, and maintain the rotation, - deposit the solution containing samarium onto the surface of the perovskite layer 140, while the tray is still rotating, - maintain rotation after the solution has been applied, for example for a period of 30 seconds. - stop the rotation of the platform.

[0085] In the case of a pin-type cell, the cell manufacturing process includes, for example, the following steps: - formation of the doped part 141 of the perovskite layer 140 by depositing a thin perovskite-based layer from a solution containing the elements: Cs, FA, Pb, Sm, I, Br (Sm can be introduced into the solution, for example, in the form of Sml2 or Sm(acac)3), - formation of the undoped part 142 of the perovskite layer 140 by depositing a perovskite layer from a standard solution (i.e. that does not contain Sm), for example, with a solution that contains the elements: Cs, FA, Pb, I, Br.

[0086] The different layers of photovoltaic cells 100 can be deposited by conventionally used techniques.

[0087] The upper electrodes 160 can be deposited by screen printing, thermal evaporation or electron beam.

[0088] The transparent electrodes 120 can be deposited by atomic layer deposition (ALD for 'Atomic Layer Deposition') or cathodic sputtering.

[0089] The buffer layer 150 can be deposited by thermal evaporation in the case of BCP or by spin coating, slot die coating, Doctor Blade deposition, ALD or sputtering in the case of an oxide.

[0090] The perovskite 140 layer can be deposited, for example, by one of the following techniques given by way of illustration and not limitation: thermal evaporation or co-evaporation (PVD), closed space sublimation (CSS), chemical vapor deposition (CVD) or ALD, pulsed laser ablation (PLD). It can also be a so-called hybrid deposition technique combining, for example, liquid deposition (centrifuge coating, scraping deposition, or slotted die, for example) and another deposition technique chosen from CSS, PVD, PLD, CVD or ALD.

[0091] The p 130 type layer can be deposited by centrifugal coating, scraping deposition, slotted die, thermal evaporation, ALD, sputtering.

[0092] The intermediate layer 200 can be deposited by sputtering or ALD.

[0093] Illustrative and non-limiting example(s)

[0094] Initially, samples with perovskite layers were prepared and characterized. One of the samples did not receive any surface treatment and the other two samples received a surface treatment to dope the perovskite with a composition of Sml2 at different concentrations.

[0095] The samples comprise, from a glass substrate, a transparent conductive oxide layer, a p-type (2PACz) layer and a perovskite layer of formula (Cs, FA)Pb(I,Br)3.

[0096] The samples were prepared as follows: - deposit, on a glass substrate covered with a layer of transparent conductive oxide (TCO), a layer of PACz by spin-coating, preferably under N2, and carry out a heat treatment for 10 min at 100°C, - deposit the perovskite layer by spin-coating, preferably under N2 and carry out a heat treatment for 60 min at 100°C.

[0097] For the first sample (sample Bl), no surface treatment was implemented on the perovskite layer.

[0098] For the other two samples, a solution of Smf2 was deposited on the perovksite layer. The concentration used for sample B2 was 2 mg / mL and the concentration used for sample B3 was 10 mg / mL.

[0099] Sml2 solutions are prepared by adding Sml2 powder to anhydrous 1 TPA. The solutions are stirred at room temperature (typically between 20 and 25 °C) for a period, for example, of 8 to 12 hours.

[0100] The solutions are deposited by dynamic dispensing. For this purpose, the doping step is carried out according to the following sub-steps: - Position the sample on a tray in a smear deposition machine, - Rotate the tray, for example at 3000 rpm. - deposit 200 pl of the Sml2 solution diluted in 1 TPA ​​onto the surface of the perovskite layer, with the tray still rotating, - maintain the rotation 30s after the deposit of the solution, - stop the rotation of the tray.

[0101] The sample can then be annealed at 100°C for 10 minutes.

[0102] The 3 samples were characterized by SEM (figures 3 and 4), UV-vis (figures 5A and 5B) and XRD ([Fig.6]).

[0103] SEM characterizations show that surface treatment with the 2 mg / ml solution (sample B2) does not affect the morphology or size of the perovskite grains. XRD characterization shows that the XRD peaks of B1 and B2 are identical (same position and same full width at half maximum or FWHM). The perovskites have the same structure. Finally, the measured band gap energy is similar for B1 and B2.

[0104] These results indicate that doping with samarium (using the 2 mg / ml solution) does not affect the structural and optical properties of the perovskite. This suggests that the doping did indeed lead to the formation of a (Cs,FA)(Pb,Sm)(I,Br)3 perovskite layer on the surface by substitution of lead with samarium. This also suggests that the bulk of the active layer 140 (i.e., the undoped portion 142 beneath the doped portion 141) remains intact.

[0105] In contrast, surface treatment with the 10 mg / ml solution (sample B3) impacts the surface morphology of the perovskite layer (grain size): the surface of the layer is composed of small samarium-based grains. However, the size and grain morphology of the bulk perovskite are only slightly affected. The XRD peaks are shifted to the left, indicating an increase in the lattice parameter ("lattice expansion"). The band gap energy of the B3 perovskite is higher than the band gap energies of perovskites B1 and B2. This suggests that, beyond a certain concentration, in addition to replacing lead atoms with samarium, the samarium atoms insert themselves into the lattice, thus modifying the optical properties of the perovskite.

[0106] Tandem silicon / perovskite photovoltaic cells were also studied. Each of these cells comprises a silicon subcell. A transparent conductive oxide (TCO) layer separates the silicon subcell from the perovskite subcell. The silicon subcell and the TCO layer are identical for each tandem cell studied. Only the perovskite subcell differs from one sample to another.

[0107] Table 1 below lists the different perovskite subcells used.

[0108] [Tables] No. Sub-cell architecture PK Concentration of Sml2 in the Al solution 2PACz / PK / Layer n / BCP / ITO / Ag A.2 2PACz / PK / BCP / ITO / Ag A.3 2PACz / PK with Sm / BCP / ITO / Ag 0.5mg / mL A.4 2PACz / PK with Sm / BCP / ITO / Ag Img / mL A.5 2PACz / PK with Sm / BCP / ITO / Ag 2mg / mL

[0109] For these different tests, the HTL layer is a 2PACz layer, the perovskite (PK) layer is a (Cs,FA)Pb(I,Br)3 layer, the TCO layer is an indium tin oxide (ITO for 'Indium Tin Oxide') layer and the electrode is silver.

[0110] The buffer layer is a BCP (bathocuproin) layer except for sample A.2 which does not contain it.

[0111] The ETL layer (layer n) of comparative example A1 is a C60 layer. In cases A.2, A.3, A.4 and A.5 there is no ETL layer.

[0112] In cases A.3, A.4 and A.5, a surface treatment with an Sml2 solution was carried out on the perovskite layer to dope it on the surface.

[0113] The other layers are identical for all 5 samples.

[0114] The tandem cells were manufactured according to the following steps: - supply double-sided polished silicon substrates ('wafer') of type n, 6 inches (i.e., 15.24 cm) in size, - deposit a-Si:H layers on both sides of the silicon substrate by PECVD, - deposit 1TTO on the back and 1 recombination TTO on the front by PVD, - cut the silicon substrate by laser to substrate sizes of 2.5 x 2.5 cm2, - deposit the Ag electrode on the back by thermal evaporation under vacuum (1.106 mbar) with a deposition rate of 5 Å / s, - deposit the 2PACz by dropping it off at the turntable under N2, - deposit the (Cs,FA)Pb(I,Br)3 perovskite layer by spinning under N2, then perform a heat treatment for 1 hour under nitrogen at 100°C, - for the Al sample, deposit the C60 by thermal evaporation under vacuum (1.106 mbar) with a deposition rate of 0.1 to 0.3 Å / s, - deposit the BCP by thermal evaporation under vacuum (1.106 mbar) with a deposition rate of 0.1 to 0.4 Å / s, - deposit 1TTO on the front panel by cathodic sputtering ('DC-sputtering') at 2500W, - deposit the upper Ag electrode by thermal evaporation under vacuum (1.106 mbar) with a deposition rate of 5 Å / s.

[0115] In order to obtain a perovskite layer with a heavily doped n-type surface, for samples A.3, A.4, and A.5, 200 pL solutions of Sml2 are deposited onto the perovskite surface by spinning (3000 rpm for 30 s). The samples are then annealed at 100°C for 10 minutes. After surface treatment, the BCP, ITO, and Ag layers are deposited as described above.

[0116] The various solutions were prepared, as before, by adding a powder of Sml2 to anhydrous PIPA. After stirring at room temperature (20-25°C) for 8 to 12 hours, the solutions were ready.

[0117] The current density as a function of voltage was measured for each tandem cell ([Fig.7]).

[0118] The following Table 2 lists the photovoltaic properties of the Si / PK tandem solar cells.

[0119] [Tables2] No. V^idemmy Jsc mA / cm2 FF % PCE% Al 1737 17.1 70.1 21.9 A.2 1031 18.0 45.3 8.9 A.3 1680 17.5 61.4 18.0 A.4 1611 17.2 56.0 15.6 A.5 1067 17.2 51.0 8.4

[0120] These different results show that the tandem cells (A.3 and A.4) without C60 and with an active layer in PK having been surface doped with a solution of Sml2 of 0.5mg / ml and Img / ml are functional with photovoltaic efficiencies close to those of the reference cell (Al).

[0121] Configuration A.2 (Standard cell without C60) leads to very low Voc, FF and therefore PCE indicating carrier extraction problems and charge recombinations.

[0122] The tandem cell (A.5) with a PK active layer having been surface-doped with a 2mg / ml Sml2 solution has a low Voc and a low PCE.

[0123] The cells of configuration A.2 (Standard cell without C60) and A.5 (configuration with Sml2 2mg / ml) have very low Voc around 1000mV, which indicates the presence of strong charge recombination at the PK / BCP interface.

[0124] In case A.2 (Standard cell without C60), the low FF also shows a strong charge carrier extraction barrier at the PK / BCP interface.

[0125] In another example, a SIMS analysis was performed on a perovskite layer, part of which was doped with samarium by spinning-on deposition of an Sml2 solution. The perovskite layer has a thickness of 575 nm. In [Fig. 8], zero corresponds to the upper surface of the perovskite (the surface on which the samarium solution was deposited), and the dashed lines correspond to the perovskite / ITO interface. The analysis shows that the Sm doping occurs at the surface of the perovskite layer and does not penetrate the entire layer ([Fig. 8]). The doping region is estimated to be approximately 92–95 nm thick.

[0126] Various embodiments and variations have been described. A person skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will become apparent to a person skilled in the art.

[0127] Finally, the practical implementation of the embodiments and variants described is within the reach of a person skilled in the art, based on the functional indications given above.

[0128] REFERENCES [1] Molenda et al. “Redox-active ions unlock substitutional doping in halide perovskites” Mater. Horiz., 2023, 10, 2845-2853 [2] Chih Shan Tan “Lead-free europium and ytterbium perovskites”, RSC Adv., 2023, 13, 19013-19019

Claims

Demands

1. An optoelectronic device (100) comprising a perovskite active layer (140), the perovskite active layer (140) being samarium-doped from a first face of the perovskite active layer (140) over a portion (141) of its thickness, a buffer layer (150), for example of PCB or oxide, being in direct contact with the first face of the perovskite active layer (140), the perovskite having the formula ABX3 with A representing an organic or inorganic cation or a combination of one or more organic cations and / or one or more inorganic cations, preferably selected from methylammonium, formamidinium, and cesium, B representing lead, tin, or a mixture thereof, X representing one or more anions, in particular one or more halogens, preferably selected from chlorine, bromine, iodine, and one of their mixtures.

2. Device according to claim 1, wherein the perovskite has the formula (Cs,FA)(Sn,Pb)(I,Br)3, preferably (Cs,FA)Pb(I,Br)3.

3. Device according to any one of claims 1 and 2, the portion (141) doped with the perovskite active layer (140) has a thickness between 50 and 150 nm, preferably between 80 and 120 nm.

4. Device according to any one of claims 1 to 3, wherein the optoelectronic device (100) is a pin-type single-junction photovoltaic cell, comprising, for example, from a face subjected to light radiation: - a substrate (110), - a lower electrode (120), - a p-type conductive layer (130), - the samarium-doped perovskite active layer (140), from the first face of the perovskite active layer (140), over a portion (141) of its thickness, - a buffer layer (150) in direct contact with the first face of the perovskite active layer (140), - an upper electrode (160).

5. Device according to any one of claims 1 to 3, wherein the optoelectronic device (100) is a pin-type perovskite tandem photovoltaic cell on silicon comprising two sub- cells stacked one on top of the other, a first sub-cell (A) being a perovskite sub-cell and a second sub-cell (B) being a silicon sub-cell, for example a silicon heterojunction sub-cell, the first sub-cell (A) comprising, for example, from a face subjected to light radiation: - a top electrode (160), - a transparent conductive oxide layer (180), - a buffer layer (150) in direct contact with the first face of the perovskite active layer (140), - the samarium-doped perovskite active layer (140), from the first face of the perovskite active layer (140), over a part (141) of its thickness, - a p-type conductive layer (130).

6. Device according to any one of claims 1 to 3, wherein the optoelectronic device (100) is a single junction nip-type photovoltaic cell, comprising, for example, from a face subjected to light radiation: - a substrate (110), - a lower electrode (120), - a buffer layer (150) in direct contact with the first face of the perovskite active layer, - the samarium-doped perovskite active layer (140), from the first face of the perovskite active layer (140), over a part (141) of its thickness, - a p-type conductive layer (130), - an upper electrode (160).

7. A method for manufacturing an optoelectronic device (100) comprising a step in which a perovskite active layer (140) is doped with samarium from a first face of the active layer (140), over a portion (141) of its thickness, thereby forming an n-type layer in the perovskite active layer (140), the perovskite having the formula ABX3 with A representing an organic or inorganic cation or a combination of one or more organic cations and / or one or more inorganic cations, preferably selected from methylammonium, formamidinium and cesium, B representing lead, tin or a mixture thereof, X representing one or more anions, in particular one or more halogens, preferably chosen from chlorine, bromine, iodine and a mixture thereof, a buffer layer (150), for example in PCB or oxide, being in direct contact with the first face of the active layer in perovskite (140).

8. A method according to the preceding claim, wherein samarium doping is achieved by depositing a solution containing samarium, for example Sml2 or Sm(acac)3, on the active layer in perovskite (140).

9. A method according to claim 8, wherein the solution comprises Sml2 and isopropanol.

10. A method according to any one of claims 8 and 9, wherein the solution is deposited by dynamic spinning in the following substeps: - rotating the structure containing the perovskite active layer (140) in a spinning deposition machine, for example at 3000 rpm, - depositing the samarium-containing solution onto the perovskite active layer (140), the structure still being in rotation, - maintaining the rotation after the solution has been deposited, for example for a period of 30s, - stopping the rotation of the structure.

11. A method according to any one of claims 8 to 10, wherein the solution has a concentration in Sml2 less than or equal to 2mg / mL, preferably between 0.5mg / mL and 2mg / mL.

12. A method according to any one of claims 8 to 11, wherein the optoelectronic device (100) is a pin-type photovoltaic cell, for example a silicon-on-perovskite tandem photovoltaic cell or a single-junction photovoltaic cell.

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