Optoelectronic device comprising metal oxide charge transport layer

Abstract

The present invention relates to an optoelectronic device comprising a plurality of layers wherein at least one layer of the plurality of layers is a charge transport layer comprising metal oxide nanoparticles and a zwitterionic ligand having a non-polar tail of general formula (I): wherein S1 represents a C3-30 alkylene group; wherein the alkylene group is linear or branched, and wherein one or more non-adjacent-CH2-groups of the alkylene group may be replaced independently of each other by a bridging group Y1; and B1 represents hydrogen.

Description

[0001] Invention Field

[0002] This invention relates to the technical field of optoelectronic devices comprising a metal oxide charge transport layer. Background of the Invention

[0004] Charge transport layers (also known as buffer layers) are known to be used in optoelectronic devices (e.g., light-emitting devices, such as displays, e.g., quantum dot displays) and photoelectric conversion devices (e.g., solar cells, such as perovskite solar cells, organic solar cells, optical sensors) to improve the efficiency and lifetime of these devices. Such charge transport layers comprise metal oxides, such as oxides of zinc, tin, titanium, tungsten, nickel, and niobium, as well as corresponding mixed metal oxides or corresponding doped metal oxides, such as Al-doped ZnO (“AZO”), antimony-doped SnO2 (“ATO”), or Cu-doped nickel oxide. Typically, these metal oxides are known in particulate form. The aforementioned charge transport layers containing metal oxides are typically fabricated using high-vacuum thermal evaporation or wet chemical (precursor-based) methods, which require a high-temperature annealing step. Both of these fabrication methods present problems in terms of cost and large-area fabrication processing.

[0005] It is also known that organic photovoltaic (OPV) and perovskite solar cells offer a promising path to low-cost, flexible photovoltaic technology, with proven efficiencies exceeding 10%. Before widespread commercialization, large-area production and stability issues must be addressed. For reliable large-area production with high yields and low shunts, thick, stable, robust, and printable / coatable buffer / charge transport layers are essential.

[0006] WO 2015 / 085441 A1 describes an organic electronic device comprising a buffer layer. This buffer layer comprises metal oxide nanoparticles coated with at least one dispersant. The dispersant used is of the formula RO-(C2H4O). m (C3H6O) n Phosphate esters of -H alkyl ethers, wherein R is C1-C 10 Alkyl group; m and n are each independently 2 to 60;

[0007] Or it could be expressed as RO(C2H4O). o (PES) p Phosphate esters of -H block copolymers, where R is C 1-10 Alkyl group; PES is a polyester derived from cyclic lactones; o is 5 to 60; p is 2 to 30; and RO(C2H4O) o The molecular weight is greater than (PES). pThe molecular weight is [value missing]. A suspension containing metal oxide nanoparticles, a dispersant, and a solvent selected from water, alcohol, glycol ether, and ketone is used as a precursor for the buffer layer. The suspension is applied to a substrate by coating or printing, followed by solvent removal, and optionally, the layer is dried at an elevated temperature.

[0008] WO 2016 / 128133 A1 describes an optoelectronic device comprising a solution-processable metal oxide buffer layer. The buffer layer comprises 70-99.9 wt% metal oxide nanoparticles. These metal oxide nanoparticles contain 1-10 wt% physically adsorbed M... z a+ R y b- The metal salt, wherein the molar fraction of metal salt cations to metal atoms / ions in the nanoparticles is 0.02-6 mol%. The metal salt cation M is selected from Zn, Al, Y, Pb, Bi, Cu, Ni, Co, Fe, Mn, Cr, V, Ti, La, Mg, Ca, SR, and Ba. The buffer layer is prepared using a suspension comprising metal oxide nanoparticles, a metal salt, and a polar solvent. The preparation process includes: applying the suspension to a (coated) substrate by coating or printing, then removing the solvent, and optionally treating the dried layer at an elevated temperature.

[0009] The suspensions described in WO 2015 / 085441 A1 and WO 2016 / 128133 A1 are suitable for direct coating onto electrodes, such as indium tin oxide electrodes or active layers comprising a fullerene-based compound (acceptor) and a second active material (donor). However, due to solvent polarity, the suspensions can damage these sensitive active layers when directly coated onto active layers (e.g., perovskite active layers, small molecule organic active layers, organic polymer active layers, organic light-emitting layers, quantum dot active layers), or onto other organic intermediate layers present on such active layers (where polar solvents typically diffuse through). Furthermore, if the layer to be coated is a hydrophobic organic charge-transport layer (e.g., cross-linked PEDOT:PSS), the high solvent polarity is also detrimental to good substrate wetting and the formation of a uniform dry film.

[0010] For sensitive perovskite active layers, WO 2015 / 085441 A1 recommends using a fullerene-based intermediate layer to prevent corrosion of the active layer.

[0011] Lu et al. (Journal of Materials Research and Technology, Vol 24, May-June 2023, Pages 8162-8170) described an inorganic / organic composite hole transport bilayer structure as a buffer layer in a carbon electrode perovskite solar cell. The inorganic layer is a NiOx layer obtained by coating an isopropanol suspension of NiOx onto the organic hole transport layer. Lu et al. proposed using charge-selective polythiophene (P3HT) as the organic hole transport layer between the perovskite and NiOx layers to avoid corrosion by the carbon paste, inhibit moisture penetration, and promote efficient charge transport and hole extraction to the anode. The isopropanol suspension of NiOx used by Lu et al. has poor colloidal lifetime stability, making it unsuitable for mass production with sufficient quality reproducibility. Furthermore, due to solvent polarity, they cannot be directly coated onto the active layer (e.g., the perovskite layer), and an intermediate layer (e.g., P3HT) is required to prevent solvent-induced corrosion of the active layer caused by the suspension. Also due to solvent polarity, such NiOx suspensions in isopropanol are incompatible with hydrophobic organic charge transport layers (such as cross-linked PEDOT:PSS), resulting in the formation of uneven charge transport layers when coated on these layers.

[0012] CN111564559A describes an electron transport layer composed of an electron transport material and zwitterionic small molecules doped in the electron transport material. The proposed zwitterionic small molecules are 3-(triphenylphosphine)propane-1-sulfonate, 4-(triphenylphosphine)butane-1-sulfonate, and Rhodamine 101 inner salt. A perovskite solar cell with the following structure is also described: ITO / P3CT / CsPbI2Br / ZnO:TPPPS / C60 / Ag electrode. The ZnO:TPPPS electron transport layer is prepared as follows: a trifluoroethanol dispersion containing ZnO nanoparticles and (3-(triphenylphosphine)propane-1-sulfonate) (TPPPS) is coated onto the perovskite layer, and then the solvent is evaporated. The zwitterionic small molecules proposed in CN111564559A appear to have limited dispersion effects. To compensate for the limited dispersion effect of zwitterionic small molecules, CN111564559A proposes using trifluoroethanol as a solvent to prepare dispersions of electron transport materials because it offers better dispersion compared to chlorobenzene, chloroform, and isopropanol. However, the technique described in CN111564559A requires the use of toxic halogenated solvents to disperse the electron transport material particles. These solvents are unsuitable for industrial production environments.

[0013] Therefore, colloidally stable suspensions of metal oxide nanoparticles are needed to produce charge transport layers. When applied to these layers (either directly or to an intermediate organic charge transport layer positioned between the metal oxide charge transport layer and the active layer), such suspensions do not damage polar solvent-sensitive active layers (e.g., perovskite active layers, small organic molecule active layers, organic polymer active layers, organic light-emitting layers, quantum dot active layers). Furthermore, if applied to an intermediate hydrophobic organic charge transport layer separating the sensitive active layer from the metal oxide charge transport layer, good wettability and uniform film formation are ensured. In addition, high-performance optoelectronic devices are needed that incorporate metal oxide charge transport layers compatible with sensitive active layers (e.g., perovskite active layers, small organic molecule active layers, organic polymer active layers, organic light-emitting layers, quantum dot active layers), which can be produced using manufacturing processes that meet industrial manufacturing requirements, such as those excluding vapor-phase processes, requiring high annealing temperatures, or suspensions containing highly toxic solvents. Furthermore, stable, health- and environmentally friendly suspensions are required for the industrial production of charge transport layers in optoelectronic devices. Suspensions with poor or limited stability are unsuitable for producing charge transport layers because they can lead to the formation of uneven, porous layers, thereby impairing the mechanical properties and conductivity of the resulting charge transport layers. Invention Overview

[0015] Therefore, one object of the present invention is to provide an optoelectronic device comprising multiple layers, wherein at least one of the multiple layers is a charge transport layer, the charge transport layer comprising metal oxide nanoparticles and zwitterionic ligands having a nonpolar tail of general formula (I):

[0016]

[0017] in

[0018] S 1 Representing C 3-30 Alkylene; preferably C 8-30 Alkylene;

[0019] The alkylene group is straight-chain or branched, and one or more non-adjacent -CH2- groups of the alkylene group can be independently bridged by a bridging group Y. 1 Substitution; provided that the heteroatoms (e.g., O and S) are not directly connected to each other, where the bridging group Y 1 Selected from -O-, -S-, -CH=CH-, and -C≡C-; and

[0020] B 1 It represents hydrogen.

[0021] This document also claims and describes a suspension for producing charge transport layers in optoelectronic devices. The suspension comprises...

[0022] (a) Approximately 0.1 wt% to approximately 40 wt% of metal oxide nanoparticles;

[0023] (b) A zwitterionic dispersant based on metal oxide nanoparticles in an amount of about 1 wt% to about 200 wt%, particularly a zwitterionic dispersant having a nonpolar tail of general formula (I);

[0024] (c) Up to 99.899 wt% of solvents with a dielectric constant of less than 10 at 20 °C.

[0025] This paper also requests and describes a method for manufacturing optoelectronic devices. Invention Details

[0027] Therefore, one object of the present invention is to meet the demand for high-performance optoelectronic devices comprising a metal oxide charge transport layer compatible with a sensitive active layer (e.g., a perovskite active layer, an organic small molecule active layer, an organic polymer active layer, an organic light-emitting layer, or a quantum dot active layer), which can be produced by a manufacturing process that meets industrial manufacturing requirements, for example, by a suspension that does not involve gas-phase processes, requires high annealing temperatures, or contains highly toxic solvents. This object is achieved by the optoelectronic device according to claim 1, the suspension for producing the metal oxide charge transport layer present in the optoelectronic device according to claim 14, and the manufacturing process according to claim 18. Preferred embodiments are disclosed in the specification and dependent claims.

[0028] The present invention will now be described in more detail.

[0029] When “preferred” implementation schemes / features are mentioned in this specification, combinations of such “preferred” implementation schemes / features are also considered to be disclosed, provided that the specific combination of “preferred” implementation schemes / features is technically meaningful.

[0030] Unless otherwise specified, the following definitions shall apply in this specification:

[0031] As used herein, the terms “a”, “an”, “the”, and similar terms used in the context of this invention (especially in the context of the claims) should be interpreted to cover both the singular and the plural, unless otherwise stated herein or explicitly provided by the context.

[0032] As used herein, the term “and / or” means that all elements of the group or only one element may be present. For example, “A and / or B” means “A only, or B only, or both A and B”. In the case of “A only”, the term also covers the case where B is not present, i.e., “A only, but no B”.

[0033] The terms “including,” “containing,” and “comprising” as used herein are used in an open-ended, non-limiting sense. It should be understood that various embodiments, preferences, and scopes can be combined freely. Thus, for example, a solution containing compound A may include other compounds besides A. However, the term “comprising,” as in its specific embodiments, also encompasses the more stringent meanings of “consistently composed of” and “composed of,” so, for example, a “solution containing A, B, and optionally C” may also consist (primarily) of A and B, or (primarily) of A, B, and C. The transitional phrase “consistently composed of” (and its grammatical variations) as used herein should be interpreted as covering the stated materials or steps as well as those that do not materially affect the essential and novel features of the claimed invention. Therefore, “consistently composed of” should not be construed as equivalent to “comprising.”

[0034] As used herein, the term "about" refers to a quantity or value that can be a specific value or some other value close to it. Typically, the term "about" indicates a specific value, meaning a range of ±5% of that value. For example, the phrase "about 100" indicates a range of 100 ± 5, that is, a range of 95 to 105. Preferably, the term "about" indicates a range of ±3% of the value, more preferably ±1%. Generally, when using the term "about," it is expected that similar results or effects can be obtained within ±5% of the indicated value according to the invention.

[0035] The term "optoelectronic device" is known in the art and refers to an electronic device capable of generating, detecting, or controlling light. Thus, such devices either convert electrical signals into optical signals (such as light-emitting devices in displays) or vice versa (such as light-absorbing devices in optical sensors and solar cells).

[0036] The terms “perovskite PV,” “OPV,” “OLED,” and “QD-LED” are known in the art and refer to optoelectronic devices comprising a “substrate” and multiple layers, at least one of which is a “charge transport layer” as defined herein. In such devices, at least one layer is an “active layer” responsible for converting light energy into electrical energy or electrical energy into light energy. Depending on the remaining layers, their structure, and their interconnections, these devices can be used for a variety of purposes, such as perovskite solar cells (“perovskite PV”), organic solar cells (“OPV”), organic light-emitting diodes (“OLED”), quantum dot light-emitting diodes (“QD-LED”), or organic photodetectors.

[0037] The terms "charge transport layer" and "buffer layer" are used interchangeably and refer to interface layers in optoelectronic devices. A charge transport layer is a general term for layers with charge-selective functions (e.g., hole transport (HTL) or electron transport (ETL)). In this invention, the term charge transport layer typically refers to different specific functions. Therefore, the term charge transport layer includes both electron transport layer and hole transport layer. The term charge transport layer includes the terms hole extraction layer (HEL), hole injection layer (HIL), electron extraction layer (EEL), and electron injection layer (EIL).

[0038] The term "active layer" refers to a photoactive layer that converts light into electrical energy (light absorption; for example, in solar cells) or converts electrical energy into light (light emission; for example, in LEDs). The active layers of "OPV," "OLED," and organic photodetectors contain polymers or small molecules, the active layers of "QD-LEDs" contain quantum dots, and the active layers of perovskite solar cells contain perovskite crystals.

[0039] The terms "perovskite" and "perovskite-type material" are known in the art and generally refer to materials that conform to... XII A VI Crystalline materials with a BX3 structure. For example, perovskite-type materials include organometallic halides such as lead methylammonium iodide (CH3NH3PbI3) or tin methylammonium iodide (CH3NH3SnI3).

[0040] The term "perovskite crystal" is known, and in particular includes crystalline compounds having a perovskite structure. This type of perovskite structure is known in itself and is described as having the general formula Mi. 1 M 2 X3 can be a cubic, quasi-cubic, tetragonal, or orthorhombic crystal, where M 1 It is a cation with a coordination number of 12 (cubic octahedral), M 2X is a cation with a coordination number of 6 (octahedral), and X is an anion in a cubic, quasi-cubic, tetragonal, or orthorhombic position in the crystal lattice. In these structures, the selected cation or anion can be replaced by other ions (random or regular substitution, up to 30 atoms), thereby forming doped perovskites or non-stoichiometric perovskites while retaining their original crystal structure.

[0041] The term "nanoparticle" is known in the art, and particularly refers to solid amorphous or crystalline particles with at least one dimension in the range of 1-100 nm. Preferably, the nanoparticles are approximately isometric (e.g., spherical or cubic nanoparticles). A particle is considered approximately isometric if the aspect ratio (ratio of the longest direction to the shortest direction) of all three orthogonal dimensions is 1-2. In an advantageous embodiment, the average first-order particle size of the nanoparticles is 2-40 nm, preferably 4-20 nm (measured by transmission electron microscopy).

[0042] The term “metal oxide nanoparticles” includes (i) pure oxide nanoparticles, (ii) nanoparticles doped with oxides, and (iii) mixed metal oxides.

[0043] The terms “surfactant,” “ligand,” “dispersant,” and “dispersing agent” are known in the art and have substantially the same meaning, referring to organic substances other than solvents used in suspensions or colloids to improve particle separation and prevent aggregation or sedimentation. Therefore, the terms “amphoteric surfactant,” “amphoteric ligand,” “amphoteric dispersant,” and “dispersing agent” are used interchangeably herein. While not strictly adhering to theory, it is believed that surfactants adhere to the particle surface physically or chemically before or after the particles are added to a solvent, thereby providing the desired effect.

[0044] The term "suspension" is known and relates to a heterogeneous fluid in which the inner phase (ip) is solid and the outer phase (ep) is liquid. The outer phase comprises one or more dispersants / surfactants, optionally one or more solvents, and optionally one or more prepolymers.

[0045] Surprisingly, it has been found that a multilayer optoelectronic device, wherein at least one layer of the multilayer is a charge transport layer comprising metal oxide nanoparticles and zwitterionic ligands, particularly zwitterionic ligands with a nonpolar tail of general formula (I), exhibits excellent efficiency and / or lifetime and can be reliably manufactured on an industrial scale in a cost-effective manner. Specifically, the manufacturing process relies entirely on a halogen-free solution method and does not involve the use of vapor-phase processes or post-treatment (e.g., plasma cleaning or annealing temperatures >150°C). The charge transport layer comprising metal oxide nanoparticles and the zwitterionic ligands described herein (wherein preferably the nanoparticles are coated with the zwitterionic ligands) is fully compatible with other layers present in the optoelectronic device (i.e., it does not degrade other layers in the optoelectronic device during manufacturing or negatively impact their performance during the optoelectronic device's lifetime) and ensures good electronic level matching between adjacent layers (e.g., electrodes, active layers, or intermediate charge transport layers). Compared to optoelectronic devices containing cationic or anionic ligands rather than zwitterionic ligands, optoelectronic devices of the present invention having zwitterionic ligands as described herein in the charge transport layer exhibit significantly higher efficiency (e.g., power conversion efficiency).

[0046] The optoelectronic device is preferably a light-absorbing optoelectronic device, more preferably a solar cell, especially a perovskite solar cell. The active layer in the solar cell may contain small organic molecules, organic polymers, or perovskite crystals, especially perovskite crystals, or be composed of them.

[0047] Typically, a solar cell includes a photoelectric conversion layer (active layer) disposed between a first electrode and a second electrode. The first and second electrodes are in electrical contact with the photoelectric conversion layer. This means they are electrically connected to the photoelectric conversion layer directly or indirectly. Direct contact means the electrode directly contacts the photoelectric conversion layer. Indirect contact means that one or more charge transport layers, particularly hole or electron charge transport layers, may exist between the electrode and the photoelectric conversion layer. Advantageously, the first and second electrodes can have partial contact with the photoelectric conversion layer, for example, when the charge transport layer is porous.

[0048] A preferred embodiment of the invention relates to a solar cell, particularly a perovskite solar cell, wherein one or more charge transport layers comprising metal oxide nanoparticles and zwitterionic ligands as described herein are arranged between a first electrode and an active layer and / or between a second electrode and an active layer. If the solar cell, particularly a perovskite solar cell, comprises at least two charge transport layers as described herein, the layers have different compositions. The charge transport layers described herein exhibit advantageous energy level matching with the active layer. In addition to the charge transport layers described herein, the solar cell, particularly a perovskite solar cell, may also comprise one or more additional charge transport layers (i.e., charge transport layers other than those comprising metal oxide nanoparticles and zwitterionic ligands), which are arranged between the first electrode and the active layer and / or between the second electrode and the active layer. In a preferred embodiment, such additional charge transport layers are arranged between the charge transport layer comprising metal oxide nanoparticles and zwitterionic ligands as described herein and the active layer.

[0049] A solar cell may include charge transport layers disposed between a first electrode and a photoelectric conversion layer, and between a second electrode and a photoelectric conversion layer. Advantageously, in this structure, the charge transport layer disposed between the first electrode and the photoelectric conversion layer is a hole transport layer, while the charge transport layer disposed between the second electrode and the photoelectric conversion layer is an electron transport layer; or, the charge transport layer disposed between the first electrode and the photoelectric conversion layer is an electron transport layer, while the charge transport layer disposed between the second electrode and the photoelectric conversion layer is a hole transport layer.

[0050] If there are two charge transport layers between the electrode and the photoelectric conversion layer, the charge transport layer in direct contact with the photoelectric conversion layer is called the "intermediate charge transport layer." If there are two electron transport layers between the electrode and the photoelectric conversion layer, the electron transport layer in direct contact with the photoelectric conversion layer is called the "intermediate electron transport layer." If there are two hole transport layers between the electrode and the photoelectric conversion layer, the hole transport layer in direct contact with the photoelectric conversion layer is called the "intermediate hole transport layer."

[0051] The additional charge transport layer described herein may be an organic layer (e.g., a small organic molecule or polymer) or an inorganic layer (e.g., a known metal oxide layer).

[0052] Examples of additional organic charge transport layers include, but are not limited to, poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), poly[(4,4′-bis(2-butyloctyloxycarbonyl-[2,2′-bithiophene]-5,5-diyl)-alternating-(2,2′-bithiophene-5,5′-diyl)] (PDCBT), poly(3-hexylthiophene-2,5-diyl) (P3HT), and N4,N4′-bis(naphthyl-1-yl)-N4,N4′-bis(4-vinylphenyl)biphenyl-4,4′-diamine (VNPB).

[0053] The first and / or second electrode can be an indium tin oxide (ITO) electrode, a fluorine-doped tin dioxide (FTO) electrode, a carbon electrode, a gold electrode, a silver electrode, a PEDOT:PSS electrode, and silver nanowires, preferably ITO or FTO.

[0054] In a preferred embodiment, the optoelectronic device is a perovskite solar cell. The perovskite crystals of the active layer are preferably formed as a polycrystalline layer, particularly a polycrystalline layer with a thickness of 0.3-5 µm.

[0055] Because the charge transport layer described herein is fully compatible with perovskite (i.e., it does not degrade the perovskite active layer present in the solar cell during manufacturing, nor does it negatively affect the performance of the solar cell during its lifetime), it can advantageously be arranged above the perovskite active layer, in direct contact with the perovskite active layer, or arranged above an intermediate organic charge transport layer. Therefore, a preferred embodiment of the invention relates to a perovskite solar cell in which the charge transport layer is arranged adjacent to the perovskite layer, or adjacent to an intermediate, preferably hydrophobic, organic charge transport layer, wherein the intermediate organic charge transport layer is arranged between the charge transport layer and the active layer.

[0056] The intermediate organic charge transport layer is preferably an organic hole transport layer, more preferably selected from PEDOT:PSS, and most preferably cross-linked PEDOT:PSS.

[0057] The first layer is arranged adjacent to the second layer, meaning that the first layer is in direct contact with the second layer. The surface of the first layer may completely or partially overlap the surface of the second layer.

[0058] Furthermore, it is preferable to arrange the charge transport layer adjacent to the electrodes (preferably carbon electrodes) in the perovskite solar cell.

[0059] Perovskite solar cells can have the following structures:

[0060] - First electrode / electron transport layer / perovskite layer / hole transport layer / second electrode, wherein at least one of the electron transport layer and hole transport layer comprises metal oxide nanoparticles and zwitterionic ligands;

[0061] - First electrode / hole transport layer / perovskite layer / electron transport layer / second electrode, wherein at least one of the electron transport layer and hole transport layer comprises metal oxide nanoparticles and zwitterionic ligands;

[0062] - First electrode / electron transport layer / perovskite / intermediate hole transport layer / hole transport layer / second electrode, wherein at least one of the electron transport layer, intermediate hole transport layer and hole transport layer comprises metal oxide nanoparticles and zwitterionic ligands;

[0063] - First electrode / electron transport layer / intermediate electron transport layer / perovskite layer / hole transport layer / second electrode, wherein at least one of the electron transport layer, intermediate electron transport layer and hole transport layer comprises metal oxide nanoparticles and zwitterionic ligands;

[0064] - First electrode / electron transport layer / intermediate electron transport layer / perovskite layer / intermediate hole transport layer / hole transport layer / second electrode, wherein at least one of the electron transport layer, intermediate electron transport layer, intermediate hole transport layer and hole transport layer comprises metal oxide nanoparticles and zwitterionic ligands.

[0065] In the above structure, a charge transport layer comprising metal oxide nanoparticles and zwitterionic ligands described herein is formed on the perovskite layer, i.e., directly applied to the perovskite layer, or applied to an intermediate charge transport layer, particularly on an organic (preferably hydrophobic) charge transport layer.

[0066] In one embodiment, the perovskite solar cell contains an intermediate electron transport layer and / or an intermediate hole transport layer, wherein the intermediate electron transport layer and / or the intermediate hole transport layer comprises metal oxide nanoparticles and zwitterionic ligands as described herein.

[0067] In another embodiment, the perovskite solar cell contains an intermediate hole transport layer selected from PEDOT:PSS and a hole transport layer comprising metal oxide nanoparticles and zwitterionic ligands as described herein, preferably selected from nickel oxide or antimony-doped tin oxide.

[0068] In another embodiment, the perovskite solar cell comprises a titanium oxide intermediate electron transport layer and an electron transport layer comprising metal oxide nanoparticles and zwitterionic ligands as described herein, preferably selected from tin oxide, titanium oxide, or antimony-doped tin oxide.

[0069] Perovskite solar cells can be transparent or semi-transparent, so that the first and second electrodes are transmissive to light.

[0070] The terms "zwitterionic surfactant," "zwitterionic ligand," "zwitterionic dispersant," and "zwitterionic dispersing agent" are used interchangeably and refer to amphoteric surfactants, a class of compounds well known in the art. These compounds contain both cationic and anionic moieties. In the zwitterionic ligands described herein,

[0071] The cationic portion is preferably selected from ammonium groups, sulfonium groups, and phosphonium groups, and more preferably from ammonium groups;

[0072] The anionic portion is preferably selected from carboxyl groups, sulfonate groups, sulfite groups, sulfate groups, phosphonite groups, phosphonate groups, phosphite groups, and phosphate groups, and more preferably from carboxyl groups, sulfonate groups, and phosphonate groups.

[0073] Particularly preferred zwitterionic ligands have a nonpolar tail of general formula (I):

[0074]

[0075] In the general formula (I), S 1 Representing C 3-30 Alkylene, wherein the alkylene is straight-chain or branched, and B 1 Represents hydrogen. One or more non-adjacent -CH2- groups of the alkylene group can be independently bridged by the group Y. 1 Substitution; provided that the heteroatoms (e.g., O and S) are not directly connected to each other. Bridging group Y 1 Selected from -O-, -S-, -CH=CH- and -C≡C-.

[0076] Amphoteric ligands may contain two nonpolar tails of general formula (I), which may be the same or different.

[0077] Bridge group Y 1 Preferably selected from -O- and -CH=CH-, more preferably -CH=CH-.

[0078] S 1 It may contain up to four bridging groups Y 1 For example, no bridging group (i.e., the nonpolar tail is alkyl), one bridging group (e.g., the nonpolar tail can be, for example, alkenyl or alkoxyalkyl, such as ethoxyalkyl, propoxyalkyl), two identical or different bridging groups, three identical or different bridging groups, or four identical or different bridging groups.

[0079] S 1 Representing C 6-30Alkylene (-(CH2)) 6-30 ), more preferably C 8-30 Alkylene, or even more preferably C 8-26 Alkylene, particularly preferred C 10-26 Alkylene, C is the most preferred. 10-20 Alkylene, wherein the alkylene is straight-chain or branched, and wherein one or more non-adjacent -CH2- groups of the alkylene can be independently bridged by a bridging group Y. 1 Substitution; provided that heteroatoms (e.g., O and S) are not directly connected to each other.

[0080] In a preferred embodiment, S 1 C 6-30 Alkylene (-(CH2)) 6-30 C is preferred. 8-30 Alkylene, more preferably C 8-26 Alkylene, particularly preferred C 10-26 Alkylene, C is the most preferred. 10-20 Alkylene, wherein the alkylene is straight-chain or branched, and wherein one of the -CH2- groups of the alkylene can be bridged by a group Y. 1 Instead, the bridging group Y 1 For -CH=CH-.

[0081] Examples of zwitterionic ligands include, but are not limited to, betaines such as caprylate glycinate, cocoamidopropyl betaine, and disodium cocoamphodiacetate; 3-(N,N-dimethylalkylammonium)propane sulfonate, alkylphosphonium zwitterions, and phosphocholine.

[0082] Specific categories of zwitterionic surfactants include:

[0083] Ammonium carboxylate of formula (I-1),

[0084] Ammonium derivatives of formula (I-2),

[0085] Phosphocholine of formula (I-3),

[0086] 1-Ammonium-2-propanol derivatives of formula (I-4),

[0087] Ammonium amide alkylcarboxylate of formula (I-5),

[0088] Acylaminoalkylammonium derivatives of formula (I-6), and

[0089] 1-(acylaminoalkyl-ammonium)-2-hydroxypropyl derivative of formula (I-7).

[0090] Ammonium carboxylate of formula (I-1),

[0091] in:

[0092] R 5 It is hydrogen or methyl.

[0093] v is 1-8, and

[0094] R 6 It is a nonpolar tail, selected from substituted or unsubstituted hydrocarbons, especially the nonpolar tail of general formula (I) described herein.

[0095] In one implementation, R 6 It is selected from alkyl, alkoxyalkyl, arylalkyl, aryloxyalkyl and alkenyl.

[0096] In a preferred embodiment, R 6 It is the nonpolar tail of the general formula (I) described herein. Particularly preferably, R 6 Selected from straight-chain or branched alkyl groups, more preferably linear (straight-chain) or branched C-chain. 8-30 Alkyl group, most preferably C 10-20 alkyl.

[0097] v preferably represents an integer between 1 and 4.

[0098] Specific subgroups of ammonium carboxylate (I-1) include: glycine salts (where R 5 (where H is v = 1), dimethylammonium betaine (where R is H, v is 1) 5 (CH3, v = 1) and ammonium propionate (where R is CH3, v is ... 5 H is 2, v is 2.

[0099] According to the ammonium derivatives of formula (I-2),

[0100] in:

[0101] R 5 R 6 And v is as defined in equation (I-1), and

[0102] FG represents a negatively charged functional group.

[0103] FG is preferably selected from sulfonates (terminal group -SO3) - ), sulfite (terminal group O-SO2) - ), sulfate (terminal group -O-SO3) - ), phosphonates (terminal group -P(OR) 7O2 - ), phosphonite (terminal group -PR) 7 O2 - ), phosphate (terminal group -OP(OH)O2) - ) and phosphite (terminal group -OP(H)O2) - ).

[0104] R 7 Preferably selected from alkyl, alkoxyalkyl, arylalkyl, aryloxyalkyl and alkenyl.

[0105] R 7 Particularly preferred are straight-chain or branched alkyl groups, more preferably straight-chain or branched C groups. 8-30 Alkyl group, C is the most preferred. 10-20 alkyl.

[0106] The preferred subgroup is ammonium sulfonate of formula (I-2.1).

[0107] in:

[0108] R 5 R 6 And v is as defined in equation (I-2).

[0109] According to formula (I-2.1), a specific subgroup of ammonium sulfonates includes sulfobetaine, wherein R 5 It is CH3.

[0110] Another preferred subgroup is ammonium sulfite of formula (I-2.2),

[0111] in:

[0112] R 5 R 6 And v is as defined in equation (I-2).

[0113] A specific subgroup of ammonium sulfite in formula (I-2.2) includes betaine sulfite, wherein R 5 It is CH3.

[0114] Another preferred subgroup is ammonium sulfate according to formula (I-2.3),

[0115] in:

[0116] R 5 R 6 And v is as defined in equation (I-2).

[0117] A specific subgroup of ammonium sulfate of formula (I-2.3) includes betaine sulfate, wherein R 5 = CH3.

[0118] Another preferred subgroup is ammonium phosphonate according to formula (I-2.4),

[0119] in:

[0120] R 5 R 6 R 7 And v is as defined in equation (I-2).

[0121] The specific subgroup of ammonium phosphonates of formula (I-2.4) includes R 5 It is a phosphonic betaine in the form of CH3.

[0122] Another preferred subgroup is ammonium phosphonate according to formula (I-2.5),

[0123] in:

[0124] R 5 R 6 R 7 And v is as defined in equation (I-2).

[0125] According to formula (I-2.5), a specific subgroup of ammonium phosphonates includes phosphonate betaine, wherein R 5 = CH3.

[0126] Another preferred subgroup is ammonium phosphate according to formula (I-2.6),

[0127] in:

[0128] R 5 R 6 And v is as defined in equation (I-2).

[0129] According to formula (I-2.6), a specific subgroup of ammonium phosphate includes betaine phosphate, where R 5 = CH3.

[0130] Another preferred subgroup is ammonium phosphite according to formula (I-2.7),

[0131] in:

[0132] R 5 R 6 And v is as defined in equation (I-2).

[0133] According to formula (I-2.7), a specific subgroup of ammonium phosphite includes betaine phosphite, where R 5 = CH3.

[0134] According to the phosphoric acid choline derivatives of formula (I-3),

[0135] in:

[0136] v is 1-8, preferably 1-4, and especially preferably 2.

[0137] R 5 and R 6 They are independently selected from hydrogen and methyl, and

[0138] R 8 It is a nonpolar tail selected from substituted or unsubstituted hydrocarbons, especially the nonpolar tail of general formula (I) as described herein.

[0139] In one implementation, R 8 Preferably selected from alkyl, alkoxyalkyl (e.g., (poly)ethoxyalkyl, such as ethoxyalkyl, di(ethoxy)alkyl, tri(ethoxy)alkyl, etc.; (poly)propoxyalkyl, such as propoxyalkyl, di(propoxy)alkyl, tri(propoxy)alkyl), arylalkyl, aryloxyalkyl and alkenyl.

[0140] In a preferred embodiment, R 8 It is the nonpolar tail of the general formula (I) described herein. Particularly preferably, R 8 Selected from straight-chain or branched alkyl groups, more preferably straight-chain or branched C4 groups. 8-30 Alkyl group, most preferably C 10-20 alkyl.

[0141] According to formula (I-3), specific subgroups of phosphoric choline include R 5 and R 6 It is a CH3-containing form of phosphoric acid choline. Mitefocin is a specific example.

[0142] A further particularly preferred zwitterionic ligand is a phosphoric acid choline derivative according to formula (I-3).

[0143] in:

[0144] v is 1-8, preferably 1-4, and especially preferably 2.

[0145] R 5 and R 6 They are independently selected from hydrogen and methyl, and

[0146] R 8 It is part of general formula (II)

[0147]

[0148] S 1 and B 1 With the meaning defined in this article,

[0149] S 2 Representing C 3-30 Alkylene;

[0150] The alkylene group is straight-chain or branched, and one or more non-adjacent -CH2- groups of the alkylene group can be independently bridged by a bridging group Y. 2 Substitution; provided that the heteroatoms, such as O and S, are not directly connected to each other, and the bridging group Y is used. 2 The selection is made from -O-, -S-, -CH=CH-, and -C≡C-, preferably -O- and -CH=CH-, and more preferably -CH=CH-; and

[0151] B 2 It represents hydrogen.

[0152] Two nonpolar tails B 1 -S 1 -and B 2 -S 2 They can be the same or different.

[0153] S 2 It may contain up to four bridging groups Y 2 For example, there may be no bridging group (i.e., the nonpolar tail is alkyl), one bridging group (e.g., the nonpolar tail may be alkenyl or alkoxyalkyl, such as ethoxyalkyl or propoxyalkyl), two identical or different bridging groups, three identical or different bridging groups, or four identical or different bridging groups.

[0154] S 2 Preferably representing C 6-30 Alkylene (-(CH2)) 6-30 ), more preferably C 8-30 Alkylene, or even more preferably C 8-26 Alkylene, particularly preferred C 10-26 Alkylene, C is the most preferred. 10-20 Alkylene, wherein the alkylene is straight-chain or branched, and one or more non-adjacent -CH2- groups of the alkylene can be independently bridged by a bridging group Y. 2 Substitution; provided that heteroatoms (e.g., O and S) are not directly connected to each other.

[0155] In a preferred embodiment, S 2 C 6-30 Alkylene (-(CH2)) 6-30 C is preferred. 8-30 Alkylene, more preferably C 8-26 Alkylene, particularly preferred C 10-26 Alkylene, C is the most preferred. 10-20 Alkylene (-(CH2))10-20 -), wherein the alkylene group is straight-chain or branched, and one of the -CH2- groups of the alkylene group may be bridged by a Y group. 2 Instead, the bridging group Y 2 For -CH=CH-.

[0156] In another preferred embodiment, S 1 and S 2 All represent C 6-30 Alkylene (e.g., S) 1 and S 2 All are C 16 Alkylene; S 1 C 16 Alkylene, S 2 C 18 Alkylene), preferably C 8-30 Alkylene, more preferably C 8-26 Alkylene, particularly preferably C 10-26 Alkylene, most preferably C 10-20 Alkylene (-(CH2)) 10-20 -), wherein the alkylene group is straight-chain or branched. One of the -CH2- groups of the alkylene group may be bridged by a Y group. 1 and / or Y 2 Replacement, where Y 1 and Y 2 It represents -CH=CH-.

[0157] In the general formula (Ic), the group R 5 and R 6 Both can represent hydrogen. Examples of such commercially available compounds include phosphatidylethanolamine (CAS No.: 1334474-30-4).

[0158] In the general formula (Ic), the group R 5 and R 6 Both can represent methyl. Examples of such commercially available compounds include phosphatidylcholine (CAS No.: 97281-44-2).

[0159] 1-Ammonium-2-propanol derivatives of formula (I-4),

[0160] in:

[0161] R 5 and R 6 As defined in equation (I-1), and

[0162] FG represents a negatively charged functional group.

[0163] FG is preferably selected from sulfonates (terminal group -SO3) -), sulfite (terminal group O-SO2) - ), sulfate (terminal group -O-SO3) - ), phosphonates (terminal group -P(OR) 7 O2 - ), phosphonite (terminal group -PR) 7 O2 - ), phosphate (terminal group -OP(OH)O2) - ) and phosphite (terminal group -OP(H)O2) - ), where R 7 As defined above.

[0164] FG particularly preferably represents sulfonates. Specific subgroups of compounds of formula (I-4) include hydroxysulfobetaine, wherein R... 5 CH3, R 6 It is the nonpolar tail of general formula (I), and FG is -SO3. - .

[0165] Ammonium amide alkylcarboxylate of formula (I-5),

[0166] in:

[0167] R 5 R 6 And v is as defined in equation (I-1), and

[0168] w is 2-5, with 2 being the preferred value.

[0169] Acylaminoalkylammonium derivatives of formula (I-6),

[0170] in:

[0171] R 5 R 6 And v is as defined in equation (I-1),

[0172] w is 2-5, preferably 2, and

[0173] FG represents a negatively charged functional group.

[0174] FG is preferably selected from sulfonates (terminal group -SO3) - ), sulfite (terminal group O-SO2) - ), sulfate (terminal group -O-SO3) - ), phosphonates (terminal group -P(OR) 7 O2 - ), phosphonite (terminal group -PR) 7 O2 -), phosphate (terminal group -OP(OH)O2) - ) and phosphite (terminal group -OP(H)O2) - ), where R 7 As defined above.

[0175] FG particularly preferably represents sulfonates. Specific subgroups of acylamide alkyl sulfonates include acylamide alkyl sulfobetaines, wherein R 5 CH3, FG -SO3 - .

[0176] 1-(acylaminoalkyl-ammonium)-2-hydroxypropyl derivatives of formula (I-7)

[0177] in:

[0178] R 5 and R 6 As defined in equation (I-1), and

[0179] FG represents a negatively charged functional group.

[0180] FG particularly preferably represents sulfonates. A specific subgroup of ammonium amide alkyl hydroxy sulfonates includes amide alkyl hydroxy sulfobetaine, wherein R 5 CH3, FG -SO3 - .

[0181] Imidazolyl-derived amphoteric surfactants: This group includes amphoteric acetates (monoacetates or diacetates) and amphoteric propionates.

[0182] In a preferred embodiment, the zwitterionic ligand is phosphocholine as defined herein.

[0183] The term metal oxide nanoparticles is as defined above. Preferably, the metal oxide nanoparticles are selected from pure metal oxides, mixed metal oxides, and doped metal oxides.

[0184] In one embodiment, the nanoparticles are selected from pure metal oxides, preferably ZnO, SnOx, TiOx, NiOx, or WOx.

[0185] In one embodiment, the nanoparticles are selected from mixed metal oxides, preferably zinc-containing mixed metal oxides, and most preferably indium gallium zinc oxide (IGZO), indium zinc oxide (IZO), zinc tin oxide (ZnSnO3), and zinc magnesium oxide (ZnMgxOy).

[0186] In one embodiment, the nanoparticles are selected from doped metal oxides, particularly doped ZnO, SnOx, TiOx, NiOx, and WOx, with SnOx and NiOx being most preferred. Suitable dopants and their amounts are known in the art. The term "doped metal oxide" refers to compositions of MOx in which the metal (M) is replaced by one or more metals (i.e., "dopants"). Dopant atoms are incorporated into M in a substitutional or interstitial manner. Y O X Within the crystal lattice, a homogeneous single phase (“solid solution”) is formed. Specific examples include ITO (indium tin oxide; typically 90% In₂O₃: 10% SnO₂) and ATO (antimony-doped tin oxide; typically 90% SnO₂: 10% Sb₂O₃). In this invention, a separated multiphase system (e.g., MO) is used. x + Fe2O3) is not considered a doped oxide. Oxide doping allows for fine-tuning of the properties of the thin films of this invention, such as conductivity, work function, and / or light absorption. The metal oxide may be doped with one or more metals at a doping level of 0.001-30 wt%, preferably 0.01-15 wt%, more preferably 0.1-10 wt% (relative to the metal). In a preferred embodiment, the dopant atoms are selected from transition metals, alkali metals, and alkaline earth metals.

[0187] According to a preferred embodiment of the present invention, therein is an optoelectronic device as described and claimed herein, wherein the metal oxide nanoparticles are selected from nickel oxide, doped nickel oxide (especially copper-doped nickel oxide), zinc oxide, doped zinc oxide (especially aluminum-doped zinc oxide), tin oxide, doped tin oxide (especially antimony-doped tin oxide), titanium oxide, and doped titanium oxide nanoparticles, preferably selected from nickel oxide, doped nickel oxide (especially copper-doped nickel oxide), tin oxide, and doped tin oxide (especially antimony-doped tin oxide) nanoparticles.

[0188] The metal oxide nanoparticles of the charge transport layer are preferably coated with zwitterionic ligands. While not strictly adhering to theory, it is believed that coating nanoparticles with zwitterionic ligands has a beneficial effect on the electronic properties of the corresponding charge transport layer. The term "coating" as used herein includes (i) direct chemical bonding (e.g., covalent bonding) between the metal oxide and the ligand as defined herein; and (ii) adsorption (e.g., physisorption) of the dispersant on the metal oxide surface. Depending on the metal oxide and the dispersant, an equilibrium may exist between chemical bonding / adsorption and free components.

[0189] The charge transport layer is preferably composed of metal oxide nanoparticles and the ligands described herein.

[0190] In one embodiment, the metal oxide nanoparticles are coated with a ligand as defined herein. In another embodiment, the present invention provides a charge transport layer having the following composition: 34-99 wt% metal oxide and 1-66 wt% zwitterionic ligand, preferably 50-97 wt% metal oxide and 3-50 wt% zwitterionic ligand, more preferably 67-94 wt% metal oxide and 6-33 wt% zwitterionic ligand, and most preferably 75-90 wt% metal oxide and 10-25 wt% zwitterionic ligand, wherein the wt% is based on the total weight of the charge transport layer.

[0191] In an advantageous embodiment, the charge transport layer is an electron transport layer, which consists of zwitterionic ligands as described herein and zinc oxide nanoparticles, doped zinc oxide nanoparticles, mixed zinc oxide nanoparticles, tin oxide nanoparticles, doped tin oxide nanoparticles, mixed tin oxide nanoparticles, titanium oxide nanoparticles, doped titanium oxide nanoparticles, or mixed titanium oxide nanoparticles.

[0192] In other advantageous embodiments, the charge transport layer is a hole transport layer composed of the zwitterionic agent described herein and nickel oxide nanoparticles, tungsten oxide nanoparticles, or antimony-doped tin oxide (ATO) nanoparticles (especially antimony-doped tin oxide nanoparticles, which preferably contain 5-30 mol% antimony relative to the total metal oxide composition, preferably 10-20 mol% antimony).

[0193] The thickness of the charge transport layer is preferably 2-200 nm, more preferably 4-100 nm, and most preferably 10-50 nm. In one embodiment, a single-layer structure may also be used, with a thickness typically 2-50 nm, preferably 4-20 nm. The thickness can be measured by profilometry, atomic force microscopy, or transmission electron microscopy.

[0194] The charge transport layer can be dense, mesoporous, or nanoparticle-like.

[0195] The average surface roughness of the charge transport layer can be below 20 nm, especially below 10 nm (measured by electron microscopy, atomic force microscopy or profilometry).

[0196] Preferably, the charge transport layer described herein is

[0197] Uniform (i.e., having a uniform thickness across its entire surface), and

[0198] The average surface roughness is below 20 nm.

[0199] A second aspect of the invention relates to a suspension and its use in the production of the charge transport layer described herein. The suspension comprises...

[0200] (a) The metal oxide nanoparticles described herein are based on a total weight of about 0.1 wt% to about 40 wt%, preferably about 0.5 wt% to about 30 wt%, more preferably about 1 wt% to about 20 wt% of the suspension;

[0201] (b) Based on the amount of metal oxide nanoparticles from about 1 wt% to about 200 wt%, preferably from about 5 wt% to about 100 wt%, more preferably from about 10 wt% to about 50 wt% of the zwitterionic ligand (dispersant) described herein.

[0202] (c) The solvent, based on a total weight of at most 99.899 wt% of the suspension, has a dielectric constant of less than 10, preferably less than 7, and more preferably less than 4 at 20°C. As used herein, the dielectric constant of the solvent refers to the dielectric constant of the solvent determined by capacitance measurement at 20°C. The hydrodynamic size D of the metal oxide nanoparticles in the suspension based on particle volume. 90 The wavelength can be less than 100 nm, preferably less than 50 nm, and most preferably less than 20 nm (measured by dynamic light scattering or centrifugal sedimentation techniques).

[0203] Advantageously, the nanoparticles are synthesized via a gas-phase pyrolysis process, preferably flame spray synthesis.

[0204] The suspension described and claimed herein is stable for at least 3 months and can be directly applied to various layers present in optoelectronic devices, including electrodes, active layers, or charge transport layers, such as perovskite active layers or intermediate organic charge transport layers.

[0205] Preferably, the solvent described herein is:

[0206] Halogen-free;

[0207] Boiling point is 70-220℃, preferably 80-150℃;

[0208] The viscosity at 25°C is 0.4 - 30 mPaS, preferably 0.5 - 15 mPaS.

[0209] The solvents described herein are preferably selected from hydrocarbons (including straight-chain, branched, and cyclic hydrocarbons), aromatic hydrocarbons, ethers (including glycol ethers), esters, and mixtures thereof, preferably from saturated hydrocarbons, unsaturated hydrocarbons, aromatic hydrocarbons, and mixtures thereof, and more preferably from straight-chain, branched, or cyclic hydrocarbons. 5-15 Alkanes, C6-12 Aromatic hydrocarbons and their mixtures.

[0210] In one embodiment, the suspension consists of metal oxide nanoparticles, zwitterionic ligands (dispersants), and solvents.

[0211] A third aspect of the invention relates to the manufacture of the innovative suspension and optoelectronic device disclosed herein. This aspect of the invention will be explained in more detail below.

[0212] The preparation of suspensions is a known procedure. The functionalization of nanoparticles with ligands is also a known procedure. These procedures can be applied to the starting materials of the suspensions of this invention.

[0213] In one embodiment, the solvent and nanoparticles are combined, for example, by mixing or ball milling. A ligand is added to the resulting initial suspension. Ligand functionalization of the nanoparticles is performed at room temperature or under heating and mixing.

[0214] In another embodiment, the solvent and ligands are combined by mixing or other means. Nanoparticles are added to the resulting initial solution. Ligand functionalization of the nanoparticles is performed at room temperature, or under heating and mixing.

[0215] Advantageously, the optoelectronic device according to the invention can be obtained by solution processing. This is considered a significant advantage because it enables the fabrication of all layers using a simple process suitable for large-area continuous processing. It is also advantageous that the suspension used in the solution process does not contain halogenated solvents (such as trifluoroethanol and chloroform), thus making it suitable for industrial production environments.

[0216] In one embodiment, the present invention provides a method for manufacturing the intermediate product described herein, the method comprising the following steps:

[0217] i) Provide a sheet-like substrate with at least one layer; and

[0218] ii) Preferably, the suspension is applied to a sheet-like substrate having at least one layer by coating or printing; and

[0219] iii) Optionally, remove the solvent from the applied suspension and / or treat the applied suspension at an elevated temperature.

[0220] The sheet-like substrate can be a glass substrate or a polymer substrate. A sheet-like substrate with at least one layer can have any of the following structures:

[0221] - Sheet-like substrate / electrode layer;

[0222] - Sheet-like substrate / electrode layer / active layer;

[0223] - Sheet-like substrate / electrode layer / active layer / intermediate organic charge transport layer;

[0224] - Sheet-like substrate / electrode layer / charge transport layer / active layer;

[0225] - Sheet-like substrate / electrode layer / charge transport layer / active layer / intermediate organic charge transport layer.

[0226] Preferably, the sheet-like substrate with at least one layer has one of the following structures:

[0227] - Sheet-like substrate / electrode layer / active layer;

[0228] - Sheet-like substrate / electrode layer / active layer / intermediate organic charge transport layer;

[0229] - Sheet-like substrate / electrode layer / charge transport layer / active layer;

[0230] - Sheet-like substrate / electrode layer / charge transport layer / active layer / intermediate organic charge transport layer.

[0231] Step i) Application of the suspension: Many processes are known to apply a liquid composition to a substrate to form a wet film; those skilled in the art can make suitable selections. For example, coating, particularly roll-to-roll coating, slot coating, spraying, ultrasonic spraying, dip coating, roll-to-roll coating, and doctor blade coating; or printing, particularly inkjet printing, pad printing, offset printing, gravure printing, screen printing, intaglio printing, and sheet-to-sheet printing. These processes are generally considered advantageous for large-scale production compared to vacuum-based processes. Depending on the composition used in step i), this step can be repeated (i.e., it can be performed multiple times). This embodiment facilitates fine-tuning of the final film thickness.

[0232] Step ii) Drying and film formation: Many methods are known for removing liquid from a wet film on a coated substrate; those skilled in the art can make appropriate selections. For example, drying at room temperature or at elevated temperatures is suitable. Drying can be carried out in air or in a protective gas such as nitrogen or argon. Low-humidity gases (e.g., nitrogen, dry air, argon) are particularly suitable.

[0233] Step iii): Temperature cleaning step: Optionally, a temperature annealing cleaning step may be performed at a temperature below 150°C. In an advantageous embodiment, in step iii), the dried nanoparticle film is annealed in air or in a protective gas at 80°C–150°C.

[0234] project

[0235] #1. An optoelectronic device comprising multiple layers, wherein at least one of the multiple layers is a charge transport layer, the charge transport layer comprising metal oxide nanoparticles and zwitterionic ligands, preferably, the nanoparticles being coated with the zwitterionic ligands.

[0236] #2. The optoelectronic device according to #1, wherein the optoelectronic device is a perovskite solar cell.

[0237] #3. The optoelectronic device according to #2, wherein the charge transport layer is arranged adjacent to the perovskite layer or adjacent to an intermediate, preferably hydrophobic, organic charge transport layer, particularly a PEDOT:PSS layer, wherein the intermediate organic charge transport layer is arranged between the charge transport layer and the perovskite layer.

[0238] #4. The optoelectronic device according to #3, wherein the charge transport layer is arranged adjacent to the electrode, preferably a carbon electrode.

[0239] #5. The optoelectronic device according to #2 has one of the following structures:

[0240] - First electrode / electron transport layer / perovskite layer / hole transport layer / second electrode, wherein at least one of the electron transport layer and hole transport layer comprises metal oxide nanoparticles and zwitterionic ligands;

[0241] - First electrode / hole transport layer / perovskite layer / electron transport layer / second electrode, wherein at least one of the electron transport layer and hole transport layer comprises metal oxide nanoparticles and zwitterionic ligands;

[0242] - First electrode / electron transport layer / perovskite layer / intermediate hole transport layer / hole transport layer / second electrode, wherein at least one of the electron transport layer, intermediate hole transport layer and hole transport layer comprises metal oxide nanoparticles and zwitterionic ligands;

[0243] - First electrode / electron transport layer / intermediate electron transport layer / perovskite layer / hole transport layer / second electrode, wherein at least one of the electron transport layer, intermediate electron transport layer and hole transport layer comprises metal oxide nanoparticles and zwitterionic ligands;

[0244] - First electrode / electron transport layer / intermediate electron transport layer / perovskite layer / intermediate hole transport layer / hole transport layer / second electrode, wherein at least one of the electron transport layer, intermediate electron transport layer, intermediate hole transport layer and hole transport layer comprises metal oxide nanoparticles and zwitterionic ligands.

[0245] #6. The optoelectronic device according to any one of #1 to #5, wherein

[0246] The zwitterionic ligand contains a cationic moiety selected from ammonium, sulfonium, and phosphonium groups, and an anionic moiety selected from carboxylates, sulfonates, sulfites, sulfates, phosphonites, phosphonates, phosphites, and phosphates; and / or

[0247] The metal oxide nanoparticles are selected from pure metal oxides, mixed metal oxides, and doped metal oxides.

[0248] #7. The optoelectronic device according to any one of #1 to #6, wherein the zwitterionic ligand is a compound of formula (I-3).

[0249] in:

[0250] v is 1-8, preferably 1-4, and especially preferably 2.

[0251] R 5 and R 6 They are independently selected from hydrogen and methyl, and

[0252] R 8 It is a nonpolar tail selected from substituted or unsubstituted hydrocarbons.

[0253] #8. The optoelectronic device according to any one of #1 to #7, wherein the metal oxide nanoparticles are selected from nickel oxide, doped nickel oxide, especially copper-doped nickel oxide, zinc oxide, doped zinc oxide, especially aluminum-doped zinc oxide, tin oxide, doped tin oxide, especially antimony-doped tin oxide, titanium oxide and doped titanium oxide nanoparticles.

[0254] #9. A suspension for producing a charge transport layer of an optoelectronic device according to any one of claims #1 to #8, wherein the suspension comprises

[0255] (a) Based on metal oxide nanoparticles with a total weight of about 0.1 wt% to about 40 wt% of the suspension;

[0256] (b) An amphoteric dispersant based on metal oxide nanoparticles in an amount of about 1 wt% to about 200 wt%;

[0257] (c) Based on a total weight of up to 99.899 wt% of a solvent with a dielectric constant of less than 10 at 20 °C.

[0258] #10. The suspension according to #9, wherein

[0259] The zwitterionic ligand contains a cationic moiety selected from ammonium, sulfonium, and phosphonium groups, and an anionic moiety selected from carboxylates, sulfonates, sulfites, sulfates, phosphonites, phosphonates, phosphites, and phosphates; and / or

[0260] The metal oxide nanoparticles are selected from pure metal oxides, mixed metal oxides, and doped metal oxides; and / or

[0261] The solvent is selected from hydrocarbons, including straight-chain, branched, and cyclic hydrocarbons; aromatic hydrocarbons; ethers, including glycol ethers; esters; and mixtures thereof, preferably selected from saturated hydrocarbons, unsaturated hydrocarbons, aromatic hydrocarbons, and mixtures thereof, and more preferably selected from straight-chain, branched, or cyclic hydrocarbons. 5-15 Alkanes, C 6-12 Aromatic hydrocarbons and their mixtures.

[0262] #11. The suspension according to #9 or #10, wherein the zwitterionic dispersant is a compound of formula (I-3),

[0263] in:

[0264] v is 1-8, preferably 1-4, and more preferably 2.

[0265] R 5 and R 6 They are independently selected from hydrogen and ethyl, and

[0266] R 8 It is a nonpolar tail selected from substituted or unsubstituted hydrocarbons, preferably selected from alkyl, alkoxyalkyl, arylalkyl, aryloxyalkyl and alkenyl.

[0267] #12. Use of the suspension according to any one of #9 to #11 for manufacturing a charge transport layer contained in an optoelectronic device according to any one of #1 to #8.

[0268] #13. A method for manufacturing an optoelectronic device according to any one of #1 to #8, wherein the method comprises the following steps:

[0269] i) Provide a sheet-like substrate with at least one layer; and

[0270] ii) Preferably, the suspension according to any one of claims 9 to 11 is applied to a sheet-like substrate having at least one layer by coating or printing; and

[0271] iii) Optionally, remove the solvent from the applied suspension and / or treat the applied suspension at an elevated temperature.

[0272] Provide the following Example The present invention will be further illustrated here. However, these examples are not intended to limit the scope of the invention.

[0273] Invention Embodiment 1:

[0274] Preparation of suspension according to the present invention

[0275] Following a procedure similar to that in EP3080849B1, NiOx nanoparticles were prepared by flame spray pyrolysis, with an average grain size of 7 nm (measured by X-ray diffraction; Scherrer method).

[0276] 10 g of the obtained NiOx nanoparticles were mixed with 297 g of toluene and 3 g of phosphatidylcholine (CAS No.: 97281-44-2) by ball milling. The resulting suspension maintained colloidal stability for at least one month, with only a very small amount of sediment forming.

[0277] Fabrication of perovskite solar cells according to the present invention

[0278] Perovskite solar cells are fabricated as follows:

[0279] The tin fluoride oxyfluoride (FTO) glass-based electrode was cleaned for 30 minutes each in an ultrasonic bath using deionized water, ethanol, acetone, and IPA, respectively. After drying, it was cleaned with plasma for 5 minutes. ETL was prepared using an aqueous solution of SnO2 nanoparticles (Alfa Aesar). The solution was diluted to 3.0 wt.% SnO2, treated in an ultrasonic bath for 10 minutes, and then filtered through a 0.45 µm PTFE filter. The solution was then spin-coated onto an ITO substrate. Subsequently, the film was annealed at 120 °C for 30 minutes to form a nanoparticle SnO2 layer.

[0280] A precursor solution of methylammonium lead iodide (MAPbI3) with a concentration of 1.2 M was prepared by dissolving methylammonium iodide (MAI) and lead iodide (PbI2) in a mixed solution of DMF and DMSO (9:1 volume ratio). This precursor solution was then deposited onto a SnO2 layer at 4000 rpm for 30 s. Finally, the film was annealed at 100 °C for 20 min.

[0281] Toluene-based PEDOT:PSS (HTL-Solar-3 from Ossila) was spin-coated with 5 wt% crosslinking agent ((3-glycidoxypropyl)trimethoxysilane from SigmaAldrich) and dried at 60°C for 5 minutes.

[0282] The NiOx dispersion was spin-coated onto the crosslinked PEDOT:PSS layer and dried at 60°C for 5 minutes.

[0283] The resulting NiOx nanoparticle layer completely covered the PEDOT:PSS layer and was defect-free. This layer exhibited a low RMS (root mean square) surface roughness of 3 nm (measured by AFM; 5×5 μm scan), indicating that the NiOx nanoparticle suspension possesses good wettability and uniform dry layer formation.

[0284] Carbon electrodes are deposited by applying carbon paste (Dyenamo) with a doctor blade and then annealed on a hot plate at 120°C for 15 minutes.

[0285] The power conversion efficiency (PCE) of the final perovskite solar cell was measured to be 19.8%.

[0286] Comparative Example 1:

[0287] Preparation of suspensions containing anionic dispersants

[0288] Toluene dispersions were prepared using the NiOx nanoparticles described in Example 1. 10 g of NiOx was combined with 297 g of toluene and 3 g of sodium dioctyl sulfosuccinate (CAS No.: 577-11-7). The mixture was then dispersed by ball milling as described in Experiment 1. The resulting suspension exhibited good colloidal stability, with only a very small amount of sediment forming.

[0289] Manufacturing perovskite solar cells

[0290] As described in Example 1, perovskite solar cells were fabricated using the NiOx described in this comparative example.

[0291] The power conversion efficiency (PCE) of the final perovskite solar cell was measured to be 16.5%, which was significantly lower than the PCE obtained using zwitterionic ligands in Example 1.

[0292] Comparative Example 2:

[0293] Preparation of suspensions containing cationic dispersants

[0294] The same procedure as in Comparative Example 1 was used, but didecylammonium bromide (CAS No.: 3282-73-3) was used instead of sodium dioctylsulfosuccinate as the dispersant. The weight ratio of NiOx nanoparticles to dispersant was 10 g: 3 g.

[0295] Manufacturing perovskite solar cells

[0296] As described in Example 1, perovskite solar cells were fabricated using the NiOx described in this comparative example.

[0297] The power conversion efficiency (PCE) of the final perovskite solar cell was measured to be 17.4%, which was significantly lower than the PCE obtained using zwitterionic ligands in Example 1.

[0298] Invention Embodiment 2

[0299] Toluene suspensions were prepared using Al-doped ZnO (AZO) nanoparticles prepared according to a procedure similar to that in EP3080849B1, with an average grain size of 12 nm (measured by X-ray diffraction; Scherrer method). 10 g of AZO was combined with 297 g of toluene and 3 g of phosphatidylcholine (CAS No.: 97281-44-2) by ball milling. The resulting suspensions maintained colloidal stability for at least one month, with only a very small amount of sediment forming.

[0300] Invention Embodiment 3

[0301] Toluene suspensions were prepared using SnO2 nanoparticles prepared according to a procedure similar to that in EP3080849B1, with an average grain size of 10 nm (measured by X-ray diffraction; Scherrer method). 10 g of SnO2 was combined with 297 g of toluene and 3 g of phosphatidylcholine (CAS No.: 97281-44-2) by ball milling. The resulting suspensions maintained colloidal stability for at least one month, with only a very small amount of sediment forming.

[0302] Invention Embodiment 4

[0303] Antimony-doped tin oxide (ATO) nanopowder with an antimony doping content of 10 mol% (Sn 0.9 Sb 0.1 O x A toluene suspension was prepared using antimony-doped tin oxide (ATO) nanopowder, prepared according to a procedure similar to that in EP3080849B1, with an average grain size of 10 nm (measured by X-ray diffraction; Scherrer method). 10 g of ATO nanopowder was combined with 297 g of toluene and 3 g of phosphatidylcholine (CAS No.: 97281-44-2) by ball milling. The resulting suspension maintained colloidal stability for at least one month, forming only a very small amount of sediment.

[0304] Stability Study

[0305] To evaluate the stability of suspensions containing NiOx particles and zwitterionic ligands, suspensions (S5, S6) according to the present invention and suspensions containing zwitterionic small molecules (C3: Rhodamine 101 inner salt; C4: TPPPS (3-(triphenylphosphine)propane-1-sulfonate)) were prepared (Table 1).

[0306] Following a procedure similar to that in EP3080849B1, NiOx nanoparticles were prepared by flame spray pyrolysis, with an average grain size of 7 nm (measured by X-ray diffraction; Scherrer method).

[0307] Suspensions S5, S6, C3, and C4 containing 2 wt% NiOx nanoparticles were prepared by ball milling NiOx nanoparticles with toluene and ligands for 60 minutes. The stability of the suspensions was evaluated by measuring the average hydrodynamic particle size at preparation time (t0) and after 14 days of storage at room temperature in the dark. The average hydrodynamic particle size was measured using a LUMiSizer® (LUMGmbH) centrifugal particle size analyzer. The results are summarized in Table 1.

[0308] Table 1:

[0309]

[0310] The suspensions S5 and S6 according to the present invention contain phosphatidylcholine and phosphatidylethanolamine as zwitterionic dispersants, respectively, and maintain high stability even after 14 days of storage, and are particularly suitable for preparing uniform charge transport layers. Phosphatidylcholine and phosphatidylethanolamine have excellent dispersing effects on metal oxide nanoparticles in solvents (e.g., toluene) with a dielectric constant of less than 10 at 20°C.

[0311] The zwitterionic small molecules Rhodamine 101 inner salt (suspension C3) and TPPPS (suspension C3) have poor dispersion effects on NiOx nanoparticles, leading to the formation of large agglomerates. Unstable suspensions C3 and C4 cannot be used to produce charge transport layers because they result in porous layers with poor mechanical properties and low electrical conductivity.

Claims

1. An optoelectronic device comprising multiple layers, wherein at least one of the multiple layers is a charge transport layer, the charge transport layer comprising metal oxide nanoparticles and zwitterionic ligands having a nonpolar tail of general formula (I): in S 1 Representing C 3-30 Alkylene; The alkylene group is straight-chain or branched, and one or more non-adjacent -CH2- groups of the alkylene group can be independently bridged by a bridging group Y. 1 Substitution; provided that the heteroatoms, such as O and S, are not directly connected to each other, and the bridging group Y is used. 1 The selection is made from -O-, -S-, -CH=CH-, and -C≡C-, with -O- and -CH=CH- being preferred; and B 1 It represents hydrogen.

2. The optoelectronic device according to claim 1, wherein... The zwitterionic ligand contains a cationic moiety selected from ammonium, sulfonium, and phosphonium groups, and an anionic moiety selected from carboxylates, sulfonates, sulfites, sulfates, phosphonites, phosphonates, phosphites, and phosphates; and / or The metal oxide nanoparticles are selected from pure metal oxides, mixed metal oxides, and doped metal oxides.

3. The optoelectronic device according to claim 1 or 2, wherein the zwitterionic ligand is a compound of formula (I-3), in v is 1-8, preferably 1-4, and especially preferably 2. R 5 and R 6 They are independently selected from hydrogen and methyl, and R 8 It is the nonpolar tail of the general formula (I).

4. The optoelectronic device according to claim 1 or 2, wherein the zwitterionic ligand is a compound of formula (I-3), in v is 1-8, preferably 1-4, and especially preferably 2. R 5 and R 6 They are independently selected from hydrogen and methyl, and R 8 It is part of general formula (II) S 1 and B 1 It has the meaning as defined in claim 1. S 2 Representing C 3-30 Alkylene; The alkylene group is straight-chain or branched, and one or more non-adjacent -CH2- groups of the alkylene group can be independently bridged by a bridging group Y. 2 Substitution; provided that the heteroatoms, such as O and S, are not directly connected to each other, and the bridging group Y is used. 2 The selection is made from -O-, -S-, -CH=CH-, and -C≡C-, with -O- and -CH=CH- being preferred; and B 2 It represents hydrogen.

5. The optoelectronic device according to claim 3 or 4, wherein R 5 and R 6 It represents hydrogen.

6. The optoelectronic device according to claim 3 or 4, wherein R 5 and R 6 Represents methyl.

7. The optoelectronic device according to any one of claims 4 to 6, wherein S 1 and S 2 different.

8. The optoelectronic device according to any one of claims 1 to 7, wherein the nanoparticles are coated with the zwitterionic ligand.

9. The optoelectronic device according to any one of claims 1 to 8, wherein the optoelectronic device is a perovskite solar cell.

10. The optoelectronic device of claim 9, wherein the charge transport layer is arranged adjacent to the perovskite layer or adjacent to an intermediate, preferably hydrophobic, organic charge transport layer, particularly a PEDOT:PSS layer, wherein the intermediate organic charge transport layer is arranged between the charge transport layer and the perovskite layer.

11. The optoelectronic device of claim 10, wherein the charge transport layer is arranged adjacent to the electrode, preferably a carbon electrode.

12. The optoelectronic device according to claim 9, wherein it has the following structure: - First electrode / electron transport layer / perovskite layer / hole transport layer / second electrode, wherein at least one of the electron transport layer and hole transport layer comprises metal oxide nanoparticles and zwitterionic ligands; - First electrode / hole transport layer / perovskite layer / electron transport layer / second electrode, wherein at least one of the electron transport layer and hole transport layer comprises metal oxide nanoparticles and zwitterionic ligands; - First electrode / electron transport layer / perovskite layer / intermediate hole transport layer / hole transport layer / second electrode, wherein at least one of the electron transport layer, intermediate hole transport layer and hole transport layer comprises metal oxide nanoparticles and zwitterionic ligands; - First electrode / electron transport layer / intermediate electron transport layer / perovskite layer / hole transport layer / second electrode, wherein at least one of the electron transport layer, intermediate electron transport layer and hole transport layer comprises metal oxide nanoparticles and zwitterionic ligands; - First electrode / electron transport layer / intermediate electron transport layer / perovskite layer / intermediate hole transport layer / hole transport layer / second electrode, wherein at least one of the electron transport layer, intermediate electron transport layer, intermediate hole transport layer and hole transport layer comprises metal oxide nanoparticles and zwitterionic ligands.

13. The optoelectronic device according to any one of claims 1 to 12, wherein the metal oxide nanoparticles are selected from nickel oxide, doped nickel oxide, especially copper-doped nickel oxide, zinc oxide, doped zinc oxide, especially aluminum-doped zinc oxide, tin oxide, doped tin oxide, especially antimony-doped tin oxide, titanium oxide, and doped titanium oxide nanoparticles.

14. A suspension for producing a charge transport layer of an optoelectronic device according to any one of claims 1 to 13, wherein the suspension comprises (a) Based on metal oxide nanoparticles with a total weight of about 0.1 wt% to about 40 wt% of the suspension; (b) An amphoteric dispersant based on metal oxide nanoparticles in an amount of about 1 wt% to about 200 wt%; (c) Based on solvents with a dielectric constant of less than 10 at 20°C, comprising up to 99.899 wt% of the total weight of the suspension; in, The zwitterionic ligand has a nonpolar tail of general formula (I): in S 1 Representing C 3-30 Alkylene; The alkylene group is straight-chain or branched, and one or more non-adjacent -CH2- groups of the alkylene group can be independently bridged by a bridging group Y. 1 Substitution; provided that the heteroatoms, such as O and S, are not directly connected to each other, and the bridging group Y is used. 1 The selection is made from -O-, -S-, -CH=CH-, and -C≡C-, with -O- and -CH=CH- being preferred; and B 1 It represents hydrogen.

15. The suspension according to claim 14, wherein The zwitterionic ligand contains a cationic moiety selected from ammonium, sulfonium, and phosphonium groups, and an anionic moiety selected from carboxylates, sulfonates, sulfites, sulfates, phosphonites, phosphonates, phosphites, and phosphates; and / or The metal oxide nanoparticles are selected from pure metal oxides, mixed metal oxides, and doped metal oxides; and / or The solvent is selected from hydrocarbons, including straight-chain, branched, and cyclic hydrocarbons; aromatic hydrocarbons; ethers, including glycol ethers; esters; and mixtures thereof, preferably selected from saturated hydrocarbons, unsaturated hydrocarbons, aromatic hydrocarbons, and mixtures thereof, and more preferably selected from straight-chain, branched, or cyclic hydrocarbons. 5-15 Alkanes, C 6-12 Aromatic hydrocarbons and their mixtures.

16. The suspension according to claim 14 or 15, wherein the zwitterionic dispersant is a compound of formula (I-3). in: v is 1-8, preferably 1-4, and more preferably 2. R 5 and R 6 They are independently selected from hydrogen and methyl, and R 8 It is either the nonpolar tail of general formula (I) or a part of general formula (II). in S 1 and B 1 It has the meaning as defined in claim 14. S 2 Representing C 3-30 Alkylene; The alkylene group is straight-chain or branched, and one or more non-adjacent -CH2- groups of the alkylene group can be independently bridged by a bridging group Y. 2 Substitution; provided that the heteroatoms, such as O and S, are not directly connected to each other, and the bridging group Y is used. 2 The selection is made from -O-, -S-, -CH=CH-, and -C≡C-, with -O- and -CH=CH- being preferred; and B 2 It represents hydrogen.

17. Use of the suspension according to any one of claims 14 to 16 for manufacturing the charge transport layer contained in the optoelectronic device according to claim 1.

18. A method for manufacturing an optoelectronic device according to any one of claims 1 to 13, wherein the method comprises the following steps: i) Provide a sheet-like substrate with at least one layer; as well as ii) Preferably, the suspension according to any one of claims 14 to 16 is applied to a sheet-like substrate having at least one layer by coating or printing; and iii) Optionally, remove the solvent from the applied suspension and / or treat the applied suspension at an elevated temperature.

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