Method for manufacturing an optoelectronic device

Abstract

Method for manufacturing an optoelectronic device. This description relates to a method for manufacturing an optoelectronic device (100) comprising a step in which a SnOxNy layer (152) with x = 2.0 ± 1.0 and y = 1.0 ± 0.75 is deposited on a perovskite layer (140). It also relates to an optoelectronic device (100) comprising a perovskite layer (140) covered by an SnOxNy layer (152) with x = 2.0 ± 1.0 and y = 1.0 ± 0.75, preferably y = 1.0 ± 0.5. Figure for the abstract: 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] Perovskite-based photovoltaic cells include an electron transport layer (ETL) located between a perovskite layer and an electrode. The ETL layer allows the electrons generated by the perovskite layer to be extracted and transported to the electrode.

[0003] 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 cell performance by limiting charge recombination at the interfaces between the perovskite and the top electrode. The buffer layer acts as an additional hole blocker and as a barrier to the diffusion of ions (particularly iodide ions) from the perovskite to the electrode, leading to improved solar cell stability (Mazumdar et al. “Stobility of Perovskite Solar Cells: Degradation Mechanisms and Remedies” (2021), Frontiers in Electronics, 2, 712785).

[0004] For ETL of perovskite-based solar cells, several buffers can be used in bilayer with C60 or PCBM, such as BCP, LiF, or transparent and selective metal oxides, in particular SnO2.

[0005] In the case of nip-configured cells, the ETL layer is formed before the perovskite layer, which allows for a wide range of deposition techniques, such as liquid deposition like chemical bath deposition or CBD (Mo et al., “Nitrogen-doped tin oxide electron transport layer for stable perovskite solar cells with efficiency over 23%” (2022), Interdisciplinary Materials, 1, 309–315). However, such techniques are not applicable to pin-configured cells. Indeed, in this configuration, the SnO2 layer is formed after the perovskite layer, and this requires soaking all the layers underlying the SnO2 layer in the solution.

[0006] For pin-configured cells, and in particular for high-performance perovskite / silicon pin tandems, the SnO2 layer obtained by deposition of layers atomic (or ALD for 'Atomic Layer Deposition') is the most widespread ETL (Gao et al., "A review on monolithic perovskite / c-Si tandem solar cells: progress, challenges, and opportunities" (2022), J. Mater. Chem. A, 10, 10811-10828).

[0007] However, the deposition of SnO2 by ALD requires a temperature above 80°C, which can degrade the lower layers already formed, particularly the perovskite layer. Furthermore, not only is the deposition time for a 20 nm thick SnO2 layer by ALD lengthy, but it also requires an expensive ultra-high vacuum and the use of chemical precursors. This deposition technique is therefore poorly suited to industrial requirements.

[0008] Another technique for depositing a layer of metal oxide such as SnO2 is sputtering. This method is faster than ALD and the deposits can be made at room temperature. However, sputtering can lead to degradation of the sample surface and the growth of layers of lower quality and less uniformity than those deposited by ALD, making it less suitable in practice.

[0009] A more suitable physical method (without chemical precursors) would be pulsed laser ablation or PLD ('pulsed laser deposition'). Indeed, a recent study demonstrated, for single-junction pin perovskite cells, that SnO2 layers deposited by PLD, at room temperature under an O2 atmosphere, have performance equivalent to SnO2 layers deposited by ALD (Soltanpoor et al., "Low Damage Scalable Pulsed Laser Deposition of SnO2 forp-in Perovskite Solar Cells" (2023), Sol. RRL 7, 2300616).

[0010] This study also showed that the perovskite layers onto which the SnO2 layers are deposited by PLD are not damaged. However, the PLD process presented still requires a high vacuum (0.005 mbar) and a relatively slow deposition rate (28 min compared to 52 min in ALD). Consequently, there is not yet a truly industrializable method for forming the SnO2 layer after the active layer in perovskite solar cells.

[0011] Currently, ETLs in pin configuration are therefore generally SnO2 layers deposited by ALD. Summary of the invention

[0012] There is a need for a manufacturing process for an optoelectronic device comprising a good quality, high-performance and easily industrializable tin oxide layer.

[0013] This goal is achieved by a manufacturing process for an optoelectronic device comprising a step in which a layer of SnOxNy with x = 2.0 ± 1.0 and y = 1.0 ± 0.75 is deposited on a layer of perovskite.

[0014] According to a particular embodiment, y = 1.0 ± 0.5.

[0015] According to a particular embodiment, the SnOxNy layer is deposited by pulsed laser ablation from a target in the presence of a gas or a mixture of gases.

[0016] According to a particular embodiment, the target is an SnOxNy target and the gas is argon.

[0017] According to a particular embodiment, the target is an SnNy target and the gas is oxygen.

[0018] According to a particular embodiment, the pressure of the gas or gas mixture is between 0.03 and 0.2 mbar, preferably between 0.05 and 0.2 mbar, during pulsed laser ablation deposition.

[0019] 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.

[0020] According to a particular embodiment, the perovskite layer is a perovskite having the formula ABX3 with A representing an organic or inorganic cation or a combination of metallic cations and / or organic cations, A preferably being the formamidinium cation associated with a cesium cation, B representing one or more metallic elements, such as lead, tin, bismuth and antimony, B preferably being lead, X representing one or more anions, in particular one or more halogens, and more particularly chosen from chlorine, bromine, iodine and mixtures thereof, X preferably being a mixture of iodine and bromine.

[0021] According to a particular embodiment, a layer doped n in PCBM or in fullerene, preferably in C60 fullerene, is disposed between the perovskite layer and the SnOxNy layer.

[0022] This goal is also achieved by an optoelectronic device comprising a perovskite layer covered by an SnOxNy layer with x=2.0 ±1.0 and y=l.0 ±0.75, preferably y=l.0 ±0.5.

[0023] According to a particular embodiment, the perovskite layer is formed of a perovskite having the formula ABX3 with A representing an organic or inorganic cation or a combination of metallic cations and / or organic cations, B representing one or more metallic elements, such as lead, tin, bismuth and antimony, X representing one or more anions, in particular one or more halogens, and more particularly chosen from chlorine, bromine, iodine and their mixtures, the perovskite preferably being CsxFAi xPb(IyBri y)3 with, preferably, x < 0.17 and 0 <y< 1.

[0024] According to a particular embodiment, the thickness of the SnOxNy layer is between 1 and 50 nm, preferably between 10 and 15 nm.

[0025] 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 first electrode, - a p-type conductive layer, - the perovskite layer, - optionally, an n-doped layer, for example a fullerene layer, in particular a C60 fullerene layer, - the SnOxNy layer, - a second electrode.

[0026] 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 electrode, - the SnOxNy layer, - optionally, an n-doped layer, for example a PCBM or fullerene layer, in particular a C60 fullerene layer, - the perovskite layer, - a p-type conductive layer. Brief description of the drawings

[0027] 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:

[0028] [Fig.1A] and [Fig.1B] represent, schematically and in cross-section, a part of an optoelectronic device, according to different particular embodiments of the invention;

[0029] [Fig.2A] schematically and in cross-section represents an optoelectronic device, in particular a single-junction pin-type perovskite solar cell, according to another particular embodiment of the invention;

[0030] [Fig.2B] schematically represents, in cross-section, an optoelectronic device, in particular a pin-type perovskite / silicon tandem solar cell, according to another particular embodiment of the invention;

[0031] [Fig.3] is a graph representing the evolution of the resistivity of SnOxNy deposited by PLD as a function of the working pressure in the chamber, under N2, according to a particular embodiment and of SnO2 deposited by PLD under O2 according to a comparative example;

[0032] [Fig.4] represents the evolution of the atomic ratios O / Sn and N / Sn quantified by Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA), as a function of N2 pressure, according to a particular embodiment and as a function of O2 pressure according to a comparative example;

[0033] [Fig.5] is a graph representing the JV ('reverse bias') characteristics of simple junction perovskite cells, under 1 Sun AMI.5 illumination, with a SnOxNy layer deposited by PLD under N2, according to a particular embodiment, and under BCP evaporation according to a comparative example;

[0034] [Fig.6] is a photograph obtained by FIB / STEM (HAADF) of a SnOxN y layer in a single pin junction cell, according to another particular embodiment of the invention;

[0035] [Fig.7] is an EDX cross-sectional map of the Sn (bottom left), O (top right) and N (bottom right) elements of the SnOxNy layer of [Fig.6];

[0036] [Fig.8] represents a chemical profile obtained by EDX of the SnOxNy layer of [Fig.6];

[0037] [Fig.9] is a graph representing the JV ('reverse bias') characteristics of PK / Si 9 cm2 tandem cells, under 1 Sun AMI.5 illumination, with a PLD-SnOxNy layer deposited under N2, according to a particular embodiment, and under BCP evaporation according to a comparative example.

[0038] The different elements are not necessarily represented at a uniform scale to make the figures more legible. Description of the implementation methods

[0039] 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.

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

[0041] 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.

[0042] 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", "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.

[0043] Unless otherwise specified, the expressions "approximately", "about", "Significantly" and "on the order of" mean at 10%, preferably at 5%.

[0044] 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.

[0045] By between X and Y, we mean that the bounds X and Y are included.

[0046] The process which will be described in more detail later is a manufacturing process of an optoelectronic device 100. The device includes at least one perovskite layer (denoted PK) 140.

[0047] The optoelectronic device 100 can be a device selected from: - a photovoltaic device: a single-junction solar cell, a solar cell in tandem configuration (Silicon / perovskite, perovskite / perovskite, CIGS / perovskite) or, more generally, a multi-junction 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.

[0048] The process includes a step in which a layer of SnOxNy 152 is formed on a layer of perovskite 140 (Figures IA and IB). The SnOxNy 152 layer has the formula SnOxNy with x = 2.0 ± 1.0 and with y = 1.0 ± 0.75 and preferably y = 1.0 + 0.5.

[0049] Such a quantity of nitrogen in layer 152 prevents the material from becoming insulating, while maintaining the desired stoichiometry of the oxide and its desired optoelectronic properties. The SnOxNy 152 layer differs from a nitrogen-doped SnO2 layer by the amount of nitrogen in the oxide. In a doped layer, the N / Sn ratio is a few percent (for example, 2%), which is more than 10 times lower, or even 50 times lower, than the N / Sn ratio of the SnOxNy layer of the present invention.

[0050] The SnOxNy 152 layer can be doped with one or more metallic elements, for example, chosen from fluorine and zirconium, to improve the properties of the 152 layer.

[0051] The thickness of the layer 152 is, for example, between 1 nm and 50 nm, and preferably between 10 nm and 15 nm.

[0052] An intermediate layer 151 can be disposed between the perovskite layer 140 and the SnOxNy layer 152 ([Fig.1B]). The intermediate layer can be an n-type layer.

[0053] The SnOxNy 152 layer can be deposited by atomic layer deposition (ALD) or by a CVD (chemical vapor deposition) method. Such methods result in a high-quality layer with good conformity.

[0054] The SnOxNy 152 layer can be deposited by other physical vapor deposition (PVD) methods such as thermal or electron beam evaporation (single-source or multi-source), sputtering or co-sputtering, or closed-space sublimation. Such deposition methods allow the deposition of uniform, crystalline, and conformal layers with a high deposition rate under vacuum.

[0055] It is also possible to deposit the SnOxNy 152 layer by solvent deposition (liquid chemical deposition), for example by spin-coating, dipping, printing, slot-die coating, doctor-blading, inkjet printing, spray pyrolysis, sol-gel, and chemical bath deposition. These liquid deposition methods are easy and quick to implement, while also having a low processing cost.

[0056] Preferably, the SnOxNy 152 layer is deposited by pulsed laser ablation (PLD). PLD (pulsed laser deposition) is a physical vapor deposition (PVD) technique, which consists of ablating a target material (for oxides, the target is a ceramic target) using a pulsed laser in the presence of a gas or a mixture of gases.

[0057] More specifically, the laser beams can be nanosecond laser beams (e.g., 15 ns) emitted at a controlled frequency (e.g., between 10 and 100 Hz). The laser beams are directed towards the target to break the bonds between atoms, which then take the form of a plasma plume with a composition very close to that of the target (stoichiometric transfer of species). The plume, generated perpendicular to the target, upon contacting a chosen substrate, results in the nucleation of a layer on the substrate, within a controlled-atmosphere vacuum chamber (or enclosure).

[0058] The UV laser (for example, a 248 nm KrF Excimer UV laser) progressively consumes the target according to a defined scan pattern. The pen traverses the substrate (compatible with 300 mm wafers) by rotating and translating it, covering it uniformly. The laser fluence (incident surface energy on the target in J / cm²) is governed by the power setting of the pens and the optical focus (the latter associated with a spot size, for example, of 5 to 10 mm² on the target).

[0059] During deposition, the deposition chamber is under high pressure of gas or gas mixture, for example under high pressure of N2. By high pressure, it is understood here that the pressure of the gas or gas mixture is between 0.03 and 0.2 mbar, preferably between 0.05 and 0.2 mbar (i.e. between 3 and 20 Pa, and preferably between 5 and 20 Pa).

[0060] The combination of high pressure in gas or gas mixture and a controlled stoichiometry target makes it possible to obtain the SnOxNy composition.

[0061] For example, the combination of high nitrogen pressure and a target with SnO2 stoichiometry yields the composition SnOxNy. The deposition atmosphere is devoid of dioxygen. It consists solely of nitrogen. Oxygen is supplied by the target and nitrogen by the gas in the chamber.

[0062] According to another embodiment, the target is a SnO2 stoichiometric target and a nitrogen-containing gas mixture, for example, a nitrogen / oxygen or nitrogen / argon mixture is used.

[0063] The SnOxNy thin film can also be obtained with an SnNx target during deposition under O2.

[0064] Such gas pressures are compatible, on the one hand, with a less demanding vacuum level (often a criticism of vacuum deposition methods), and, on the other hand, with a PLD process capable of high deposition rates and uniform deposition even over large areas (for example, with 300mm / G12 substrates). The 300mm / G12 substrates comprise a square substrate (G12 (or M12) format) of 21x21cm² able to fit inside the footprint of a 300 mm diameter (295 mm) disc substrate ('wafer').

[0065] Moreover, this deposition method avoids the use of chemical precursors, as with ALD.

[0066] Such pressures make it possible to produce SnOxNy layers in a more industrialized way.

[0067] In particular, such pressures are advantageous in the case of the development of electron transport layer (ETL) for perovskite solar cells.

[0068] Preferably, the SnOxNy 152 layers are deposited at room temperature (typically between 20 and 25°C). The underlying perovskite is not damaged (so-called 'low-damage' deposition). They could be deposited at a higher temperature, for example up to 150°C.

[0069] An annealing step can be implemented after the deposition of the SnOx Ny 152 layer to improve the crystallinity of the layer. Such a step is, for example, carried out for nip-type solar cells, or after the deposition of an inorganic perovskite 140 layer.

[0070] The layers thus obtained by PLD exhibit low resistivity and a suitable stoichiometry. Such characteristics are achievable at high pressure, particularly under N2, but would not be achievable under a conventional O2 atmosphere.

[0071] In addition, the 152 layers obtained exhibit good transparency.

[0072] It is possible to deposit one or more SnOxNy 152 layers or several SnOx Ny layers with different processing parameters to obtain a multilayer made up of several layers having different properties.

[0073] It is also possible to fabricate a layer 152 with a composition gradient. This can, for example, allow the first part of the layer to be formed in such a way as to preserve the underlying layer(s) (i.e., not to damage them; this first part acting as a buffer layer) or to passivate interface defects that may be present on the surface of the underlying layer, and then to form a second part (forming the upper layers) to achieve optimal electrical / optical properties. The use of a multilayer can allow the underlying and upper layers to be tuned to promote the extraction or injection of charge carriers, and / or optical confinement or antireflection.

[0074] Such layers can be deposited during the fabrication of perovskite solar cells. The solar cells can be single-junction or tandem cells. The SnOxNy 152 layer of the device can be a charge-transporting or charge-injection layer.

[0075] Solar cells can be of nip type or pin type (so-called inverted type structure).

[0076] The manufacturing process of a silicon-perovskite (Si / PK) tandem solar cell or a single junction solar cell implementing a step of deposition of an SnOxNy layer deposited by PLD makes the device very industrializable (compared to a deposition step by ALD).

[0077] For example, the simple pin junction solar cell comprises successively from the face exposed to light radiation ([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'), in particular indium tin oxide (or ITO for 'Indium Tin Oxide'), - a p 130 type conductive layer (also called a hole transport layer (HTL for 'Hole Transport Layer'), for example in a carbazole, notably 2PACz ((2-(9H-carbazol-9-yl)ethyl)phosphonic acid)), - an active layer of perovskite 140, - an n-type conducting layer (also called an electron transport layer (ETL), for example formed of a bilayer 150 comprising an n-doped layer 151, for example a fullerene layer, in particular a C60 fullerene layer, and the SnOxNy layer 152 or for example formed of the SnOxNy layer 152, - a second electrode 160 called the upper electrode made of metal, for example silver or aluminium.

[0078] Metallic contacts, for example in Cr / Au, are formed on the substrate 110 (not shown). They can be offset.

[0079] Illumination occurs through substrate 110.

[0080] The active layer 140 is a layer made of perovskite material of general formula ABX3 with: A representing an organic or inorganic cation or a combination of metallic cations and / or organic cations, B representing one or more metallic elements, such as lead (Pb), tin (Sn), bismuth (Bi) and antimony (Sb), X representing one or more anions, in particular one or more halogens, more particularly chosen from chlorine, bromine, iodine and their mixtures.

[0081] 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 metallic cations, for example cesium and / or rubidium. The organic cation(s) may be chosen from alkyl-ammonium cations such as (for example a methylammonium (MA) type cation) and formamidinium (FA) cations.

[0082] Preferably, A represents the formamidinium cation (FA), possibly associated with cesium; B is chosen from lead, tin, bismuth, antimony and mixtures thereof (preferably lead) and X is chosen from chlorine, bromine, iodine and mixtures thereof (preferably a mixture of iodine and bromine).

[0083] The perovskite material can be a compound of formula CsxFAi xPb(Ii yBry)3 with, for example, x < 0.17; 0 < y < 1 and FA symbolizing the formamidinium cation or CsxFAi xPbI3 yBry (with 0 < y < 1 or 0 < y < 3).

[0084] In the case of a bilayer, the C60 fullerene can be replaced by another n-type material, such as for example a polyethyleneimine in particular polyethyleneimine ethoxylated (PEIE), a thiophene such as thiophene-C61-methyl butyrate, or another fullerene, for example C70, C80 fullerene, C84 fullerene.

[0085] The p-type material could also be chosen, for example, from sodium poly(styrene sulfonate) (PSS), oxides such as WO3, MoO3, V2O5 and NiO, or from pi-conjugated polymers (such as poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3-hexylthiophene) or P3HT), or one of their mixtures.

[0086] The obtained single junction pin-type perovskite solar cells exhibit a photovoltaic efficiency (PCE) of 14.3%, for an open circuit voltage (Voc) of 1032 mV, a short circuit current (Jsc) of 21.9 mA / cm2 and a form factor (FF) of 63.1%.

[0087] The pin-type silicon perovskite tandem solar cell is a structure comprising two subcells stacked one on top of the other. The upper subcell is a perovskite subcell while the lower subcell is silicon, in particular it is a silicon heterojunction subcell ([Fig.2B]).

[0088] Perovskite tandem photovoltaic cells on silicon to maximize solar energy conversion efficiency.

[0089] The two subcells 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) chosen from, for example, ITTO (indium tin oxide), AZO (aluminum zinc oxide), IZO (indium zinc oxide).

[0090] The perovskite-based subcell comprises successively, from the upper face exposed to the sun: - a so-called upper electrode, preferably transparent, 160 - an n-type conductive layer (also called an electron transport layer (ETL)), for example formed of a bilayer 150 comprising an n-doped layer 151 in fullerene, in particular in C60 fullerene, and the SnOxNy layer 152 in contact with the upper electrode, or for example formed of the SnOxNy layer 152, - an active layer of perovskite 140, - a p 130 type conductive layer (HTL).

[0091] The silicon heterojunction subcell includes, for example, from the layer intermediate 200 or from the perovskite-based subcell: - a layer of n-310 doped amorphous silicon, - preferably a layer based on intrinsic amorphous silicon 320 serving as a passivation layer, - a n-330 doped crystalline silicon substrate, - preferably, a layer based on intrinsic amorphous silicon 340 serving as a passivation layer, - a layer of p-doped amorphous silicon, - a 360 electrode, preferably transparent.

[0092] Metallic contacts 370, for example in Cr / Au, are formed on the electrode 360 ​​of the silicon-based subcell, and other metallic contacts 170 can be formed on the upper electrode 160 of the perovskite-based subcell. They can be offset at the illuminated face.

[0093] The illumination of a Si / PK tandem device is achieved from the perovskite-based subcell.

[0094] The materials previously described for the single junction perovskite cell can be used for the perovskite-based subcell.

[0095] The obtained perovskite pin tandem solar cells on silicon exhibit a photovoltaic efficiency (PCE) of 20.0%, for an open circuit voltage (Voc) of 1766 mV, a short circuit current (Jsc) of 16.6 mA / cm2 and a form factor (FF) of 68.1%.

[0096] Pin-type cells have been particularly described. Solar cells could also be single-junction NiP-type cells or tandem NiP-type cells. Indeed, the SnOxNy layer deposition method, particularly by PLD, can be used for these different structures since this method requires a low thermal budget, can be implemented for many substrates, and allows the formation of stable layers with the desired composition, which is favorable for obtaining good photovoltaic properties. The layers obtained have a suitable and adjustable stoichiometry, are very smooth, and are of Controllable morphology (more or less dense, columnar or non-columnar). Therefore, they are suitable for the subsidiary growth of a perovskite for single-junction NiP cells. They are also adapted to the thermal stress of a silicon heterojunction subcell (200°C max due to the amorphous silicon) for tandem NiP cells.

[0097] Illustrative and non-limiting example

[0098] In this first comparative example, the deposition of a layer of tin oxide 152 was carried out by PLD under O2 and under N2.

[0099] For PLD deposition under O2, the O2 pressure in the chamber was initially increased from 0.005 mbar to reduce the vacuum level requirement. The conductivity of the formed SnO2 layer increases (i.e., the resistivity decreases) until it reaches a maximum around 0.017 mbar. The addition of oxygen then rapidly leads to the filling of the oxygen vacancies that govern the desired n-type semiconductor property. The layer then becomes insulating, increasing the resistivity beyond the measurement range ([Fig. 3]).

[0100] Surprisingly, it has been observed that deposition under nitrogen (N2) makes it possible to achieve high conductivity without requiring a high vacuum level. It is therefore possible to obtain a material with good electrical properties at high pressure by replacing oxygen with nitrogen ([Fig.3]).

[0101] Furthermore, the obtained layers were characterized by RBS chemical analysis to determine their stoichiometry. Increasing the O2 pressure leads to an excess of oxygen (responsible for the insulating properties), whereas high-pressure deposition under N2 in the chamber results in an SnOxNy layer with the desired O / Sn ratio. Thus, an N / Sn ratio of 1 was obtained by performing SnO2 deposition by PLD under nitrogen at 0.15 mbar, while maintaining an O / Sn ratio of 2. ([Fig. 4]).

[0102] The presence of nitrogen in the layer under these conditions was confirmed by NRA ([Fig.4]), a variant of RBS adapted to light elements.

[0103] A SnOxNy deposit was then integrated into a single-junction perovskite solar cell (for example, a pin-configured photovoltaic cell as shown in [Fig. 2A]). The resulting cell was compared with the same cell having a BCP deposit instead of SnOxNy.

[0104] The manufacturing process for single-junction cells may include the following steps: - washing the substrate (in particular a glass substrate coated with an ITO layer) with acetone, IPA, then deionized water (EDI) under ultrasound, - deposition of Cr / Au contacts on ITO, by thermal evaporation under vacuum (1.104 mbar) with a deposition rate of 0.1 to 0.5 Å / s, - 30-minute UV-ozone treatment of the substrate, - Deposition of the p-type layer in 2PACz, by spinning and then annealing at 100°C, - Deposition of the perovskite layer, by spinning and then annealing at 100°C, - Deposition of a 15 nm C60 layer, by thermal evaporation under vacuum (1.106 mbar) with a deposition rate of 0.1 to 0.3 Å / s, - Deposition of the 10 nm SnOxNy layer by pulsed laser ablation (PLD) at 4 J / cm² and 50 Hz, with an N₂ flux of 22 sccm corresponding to a working pressure of 1.5 x 10⁻¹ mbar; for comparison, the BCP layer was deposited by thermal evaporation at -6°C under vacuum (1.10 mbar) with a deposition rate of 0.1 to 0.3 A / s for the reference cell, - deposition of the upper Ag electrode by thermal evaporation under vacuum (5.106 mbar) with a deposition rate of 0.5 to 1.5 Â / s.

[0105] In particular, the step of depositing the 10 nm thick SnOxNy layer onto the C60 layer, from an SnO2 target and under high nitrogen pressure, at room temperature, may include at least the following substeps: - loading of substrates / cells into the chamber (onto a 200 mm test substrate or on a custom-made holder), - isolation of the enclosure, stabilization of the laser energy and start-up of the working pressure setpoint (high pressure of N2: 0.15 mbar at a rate of a flow of 22 sccm); - deposition of the layer at 50 Hz (50 laser pulses per second), in 5 radial back-and-forth passes of the plasma plume on the 200 mm substrate (3 min 42 sec deposition); - restoring the enclosure to equilibrium; - unloading of substrates / cells.

[0106] The conversion efficiencies of the two cells were compared ([Fig.5]). The cell with the SnOxNy layer deposited by PLD achieves a photovoltaic conversion efficiency (PCE) of 14.3% under 1 sun AMI.5 (1000 W / m2), i.e. a relative performance of 86% compared to the reference cell with BCP as the ETL buffer.

[0107] This confirms that SnOxNy layers can be deposited under high nitrogen pressure. The process is industrializable. The remarkable properties of the electron transport layers (ETLs) are preserved, without damaging the underlying perovskite.

[0108] A cross-sectional view of the layer within the cell was taken by scanning transmission electron microscopy (STEM) after sectioning by ion beam microscopy (IBM). The images reveal a deposit of very good uniformity, considering the high deposition rate, without deterioration of the underlying layers and (Figures 6 and 7). The chemical profile of the layer obtained by EDX confirms the presence of nitrogen, uniform over the thickness of the layer ([Fig.8]).

[0109] Finally, the study led to the integration of the proposed SnOxNy layer into a tandem pin cell (such as the one shown in [Fig.2B]). It has a surface area of ​​9 cm2.

[0110] The process for manufacturing the tandem cell may include the following steps: - deposition of intrinsic and doped hydrogenated (passivating) amorphous silicon layers (a-Si:H), by plasma-enhanced chemical vapor deposition (PECVD), on both sides of a 6-inch type n c-Si wafer, - Deposition of a 100 nm thick ITO layer, by DC magnetron sputtering, on the a-Si:H (p) for the pin configuration, to form the back contact, - Deposition of a thin TCO layer on the a-Si:H (n) for the pin configuration, to form the recombination layer between the lower and upper cells, - Cutting of the lower silicon cells into four 50 mm x 50 mm samples, - Silver is deposited by thermal evaporation on the back of the samples to form a contact across the entire surface, - deposition of a 2PACz layer on the recombination TCO side by spinning deposition and annealing at 100°C, - deposition of a perovskite layer by turning and annealing at 100°C, - deposition of a C60 layer by thermal evaporation under vacuum (1.106 mbar) with a deposition rate of 0.1 to 0.3 Å / s, - deposition of the SnOxNy layer by pulsed laser ablation (PLD) at a fluence of 4 J / cm2 and at 50 Hz, with an N2 flux of 22 sccm corresponding to a working pressure of 1.5 x 10⁻¹ mbar; for comparison, a BCP layer in a reference cell was deposited by thermal evaporation under vacuum (1 x 10⁶ mbar) with a deposition rate of 0.1 to 0.3 Å / s, - Deposition of an ITO layer by cathodic sputtering (DC-sputtering) at 2500W with an argon flow of 315 sccm and an O2 flow of 6 sccm. - deposition of a silver top electrode by thermal evaporation under vacuum (1.10 mbar) with a deposition rate of 5 A / s.

[0111] Although the yield does not yet reach that of a reference with SnO2 by ALD, it remains promising, as it reaches 20.0% under 1 sun AMI.5 irradiance (1000 W / m2), representing a relative performance of 87% compared to the reference ([Fig.9]). Nevertheless, this confirms that the SnOxNy layer is usable in a Large area tandem cell. Future optimization of the layer will be carried out based on this first operating point.

[0112] Table 1 below lists the properties of solar cells obtained with a literature SnO2 layer (by ALD or PLD) and an SnOxNy layer deposited by PLD under N2, in terms of figure of merit, ease of fabrication and optical and electrical properties.

[0113] [Tables 1] ALD-SnO2 PLD-SnO2 (pure O2) PLD-SnOxNy (pure N2) Factor of Merit or PCE (%) 18.3 17.8 14.3 Illuminated Area (cm2) 0.01 0.01 0.13 PCE (%) per 9 cm2 in tandem 23.0 - 20.0 Material Source Precursors Ceramic Target Ceramic Target Vacuum (mbar) 0.00001 0.005 0.15 Thickness (nm) 24 19 10 Deposition Rate (nm / m in) 0.46 0.67 2.7 at 50 Hz (up to 16 at 300 Hz) Deposition Time (min) 52 28 3.7 at 50 Hz (approx. 40 s at 300 Hz) Resistivity (Q.cm) - 16 0.0076 Transmittance above 400 nm (%) Greater than 84 Greater than 65 Greater than 83 Band gap with the Tauc method (eV) 3.3 3.1 3.6

[0114] In addition to the advantages related to the manufacturing process (particularly the vacuum level) and the good conductivity obtained, the layers have a transmittance as high as their counterparts obtained by ALD and a higher bandgap energy, which would allow for better hole blocking. Furthermore, nitrogen deposition by PLD is four times faster than the depositions mentioned in the literature.

[0115] The work function and valence band of SnOxNy were measured by ultraviolet photoelectron spectroscopy (UPS). The results show a band alignment favorable to electron extraction and hole blocking.

[0116] Finally, the integration into a photovoltaic device did not benefit from interface passivation, nor from an illumination surface as restricted as in the literature, two factors likely to inflate performance.

[0117] 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.

[0118] 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.

Claims

Demands

1. Method of manufacturing an optoelectronic device (100) comprising a step in which a layer of SnOxNy (152) with x = 2.0 ± 1.0 and y = 1.0 ± 0.75 is deposited on a layer of perovskite (140).

2.

3. A method according to the preceding claim, wherein y = 1.0 ± 0.

5. A method according to any one of the preceding claims, wherein the SnOxNy (152) layer is deposited by pulsed laser ablation from a target in the presence of a gas or a mixture of gases.

4. Method according to claim 3, wherein the target is a SnOxNy target and the gas is argon.

5. Method according to claim 3, wherein the target is an SnNy target and the gas is oxygen.

6. A method according to any one of claims 3 to 5, wherein the pressure of the gas or gas mixture is between 0.03 and 0.2 mbar, preferably between 0.05 and 0.2 mbar, during pulsed laser ablation deposition.

7. A method according to any one of the preceding claims, 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.

8. A method according to any one of the preceding claims, wherein the perovskite layer (140) is a perovskite having the formula ABX3 with A representing an organic or inorganic cation or a combination of metallic cations and / or organic cations, A preferably being the formamidinium cation associated with a cesium cation, B representing one or more metallic elements, such as lead, tin, bismuth and antimony, B preferably being lead, X representing one or more anions, in particular one or more halogens, and more particularly selected from chlorine, bromine, iodine and mixtures thereof, X preferably being a mixture of iodine and bromine.

9. A method according to any one of the preceding claims, wherein a layer doped n (151) with PCBM or fullerene, preferably in fullerene C60, is arranged between the perovskite layer (140) and the SnOxNy layer (152).

10. Optoelectronic device (100) comprising a perovskite layer (140) covered by an SnOxNy layer (152) with x = 2.0 ± 1.0 and y = 1.0 ± 0.75, preferably y = 1.0 ± 0.

5.

11. Device according to claim 10, wherein the perovskite layer (140) is formed of a perovskite having the formula ABX3 with A representing an organic or inorganic cation or a combination of metallic cations and / or organic cations, B representing one or more metallic elements, such as lead, tin, bismuth and antimony, X representing one or more anions, in particular one or more halogens, and more particularly selected from chlorine, bromine, iodine and mixtures thereof, the perovskite preferably being CsxFAi xPb(IyBri y)3 with, preferably, x < 0.17 and 0 < y < 1.

12. Device according to any one of claims 10 and 11, wherein the thickness of the SnOxNy (152) layer is between 1 and 50 nm, preferably between 10 and 15 nm.

13. Device according to any one of claims 10 to 12, 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 first electrode (120), - a p-type conductive layer (130), - the perovskite layer (140), - optionally, an n-doped layer (151), for example a fullerene layer, in particular a C60 fullerene layer, - the SnOxNy layer (152), - a second electrode (160).

14. A device according to any one of claims 10 to 12, wherein the optoelectronic device (100) 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 electrode (160), - the SnOxNy (152) layer, - possibly, an n-doped layer (151), for example a PCBM or fullerene layer, particularly a C60 fullerene layer, - the perovskite layer (140), - a p-type (130) conductive layer.

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