Electron transport self-assembled monolayer compounds for optoelectronic and / or photoelectrochemical devices and manufacture thereof

Abstract

The present disclosure provides novel electron transporting naphthalene-diimide and naphthalene-imide compounds containing phosphonic acid or phosphoric acid as anchoring groups, as well as their use as electron transporting materials in optoelectronic and / or photoelectrochemical devices, particularly photovoltaic devices, and methods for their manufacture. The structure of the compounds according to the invention allows covalent binding to transparent conductive oxide surfaces at suitable energy levels, minimizing thickness at low temperatures.

Description

Technical Field

[0001] The present invention generally relates to novel self-assembled monolayer compounds, and their use as electron transport materials in optoelectronic and / or photoelectrochemical devices, particularly photovoltaic devices, and methods for their manufacture. Background Art

[0002] In the past few decades, there has been a strong interest in renewable energy, especially the most efficient of them all - solar energy. The conversion of solar energy into electricity using thin-film third-generation photovoltaic (PV) devices has been widely explored in the past two decades. Sandwich / monolithic PV devices consisting of a mesoporous photoanode with organic / inorganic light harvesters, a redox electrolyte / solid-state hole conductor, and a counter electrode have received significant interest due to their ease of fabrication, flexibility in material selection, and low cost of production.

[0003] Organic-inorganic metal halide perovskite solar cells (PSCs) have developed rapidly in recent years, with their power conversion efficiency (PCE) increasing from 3.8% in 2009 to an amazing 26.1% in 2023; [1] These values are now comparable to those of established solar cell technologies on the market, such as crystalline silicon (C-Si) and copper indium gallium diselenide (CIGS). In addition, PSCs can be fabricated using low-cost, scalable, and simple solution-processing techniques, further highlighting the promise of PSCs as a future mainstream technology. [2] Furthermore, when combined with C-Si, CIGS, organic, or another PSC as the bottom cell technology, PSCs can also be integrated as the top cell into tandem cells, generating a PCE far higher than that of the sub-cells, opening the path to affordable ultra-high-efficiency PV. [3] Despite the amazing efficiency shown by perovskite solar cells, there are still significant obstacles to overcome before this technology can be commercialized. The most important of these is the lack of stability of the devices, mainly due to the decomposition of the perovskite absorber when exposed to the surrounding environment.

[0004] Conventional PSC devices consist of two electrodes, a perovskite photoabsorber, an n-type electron transport layer (ETL), and a p-type hole transport layer (HTL). [4] The perovskite layer is sandwiched between the ETL and HTL for efficient charge transport. External electrodes, including transparent conductive glass coated with a transparent conductive oxide (TCO) such as indium tin oxide (ITO) or fluorine-doped tin oxide (FTO), and a counter electrode (Au, Ag, or carbon), are used for charge collection. Three types of device configurations are commonly used to fabricate PSCs, including mesoporous n-i-p, planar n-i-p, and planar p-i-n structures, where n represents the ETL, p represents the HTL, and i represents the perovskite layer ( Figure 1)。So far, the n-i-p structure has systematically outperformed its p-i-n counterpart. [5]

[0005] To design stable and efficient PSCs, the selection of electron and hole transport layers as well as perovskite materials is crucial. The ETLs composed of metal oxides (TiO2, ZnO, SnO2) facilitate the collection of photo-generated electrons from the perovskite layer to the corresponding electrodes for conventional PSCs and hydrophobic [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) or its derivatives for inverted PSCs. [6] On the other hand, 2,2’,7,7’-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9’-spirobifluorene (spiro-MeOTAD) is the most commonly used hole transport material (HTM) for conventional PSCs. In the case of inverted PSCs, different HTLs are formed by different organic small molecules including emerging self-assembled monolayers (SAMs) from copper (CuI, CuCrO2) and nickel (NiOx) compounds as well as polymers such as poly(3,4-ethylenedioxythiophene) polystyrenesulfonate (PEDOT:PSS) and poly[bis(4-phenyl)(2,5,6-trimethyl-phenyl)amine] (PTAA). [7]

[0006] Self-assembled monolayers (SAMs) have recently emerged as a viable alternative to traditional charge transport layers in PSCs. [8] In particular, SAM molecules based on carbazole and phosphonic acid groups, commonly referred to as nPACz where n is the aliphatic chain length, have attracted great interest as hole-selective contacts. The carbazole group has a strong electron-donating moiety and thus exhibits hole selectivity, while the phosphonic acid group can covalently bind to the transparent conductive oxide (TCO) surface to form a monolayer. [7-9] Due to their fast hole extraction and good electron passivation at the SAM / perovskite interface, perovskite-based p-i-n single-junction and monolithic perovskite / silicon tandem solar cells have achieved amazing PCEs of approximately 26.1% and 32.5%, respectively. [1]

[0007] Although new SAMs for hole collection of a series of perovskite photoabsorbers have been intensively studied, reports on the design of novel electron-selective SAM molecules are still scarce. Arguably, this is due to the relative scarcity of suitable electron acceptors for the synthesis of electron-selective materials and the effort required to identify and apply non-fullerene derivatives as electron-selective materials in PSCs. [11,12] Generally, the class of organic ETLs is dominated by fullerene derivatives, including C60 and its functionalized analogues (e.g., PC 61 BM, PC 71 BM, etc.). [6,11,12]However, the application of fullerene-based ETLs in solution processing is limited by the poor solubility of unmodified fullerenes in organic solvents. Additionally, the synthesis and purification of modified fullerenes, especially C70 derivatives, are challenging and require complex and expensive multi-step processes.

[0008] As an alternative to fullerenes, small molecules based on naphthalenediimide (NDI) offer favorable ETL properties such as high electron affinity, relatively high electron mobility, and photochemical stability with a simple synthesis procedure. [6,13-15] First, NDI-based SAMs such as N,N'-bis(1-n-hexylpyridin-4-ylmethyl)-1,4,5,8-naphthalenetetracarboximide and ammonium-containing NDI polymers are used as the intermediate layer between the PC 61 BM and the top-contact metal electrode to improve the performance of p-i-n PSCs. [13,16,17] Subsequently, NDI-based SAMs containing carboxyl anchoring groups are directly applied to indium tin oxide (ITO) substrates to modify their work function, enabling electron collection in n-i-p PSCs.

[18] These NDI-based devices exhibit a PCE of 16% and a fill factor (FF) of 70%. However, while these results show potential, they lag behind the best performance of conventional n-i-p PSCs, which typically rely on metal oxide ETLs (e.g., TiO2 or SnO2). Notably, conventional solution-processed metal oxide ETLs require additional surface modification with organic or inorganic materials to minimize interfacial charge losses, posing challenges to the scalability of PSCs.

[0009] The present invention provides electron-transporting NDI-based compounds functionalized with phosphonic or phosphoric acid groups, which can be directly anchored to transparent conductive oxides (ITO, FTO, etc.) with minimal thickness. Compared to traditional low-temperature processed metal oxide ETLs that typically require higher temperature treatment (≥150 °C), these novel electron-selective SAMs are solution-processable and require moderate temperatures (usually around 100 °C), which is beneficial for certain applications of n-i-p PSCs, improving efficiency and stability. Additionally, the need for additional surface modification with organic or inorganic materials to minimize interfacial charge losses and reduce material consumption is a recent issue to be addressed, especially in providing scalable technologies. Moreover, such organic semiconductors are attractive not only for photovoltaic devices but also for the development of other low-cost, high-performance optoelectronic devices such as light-emitting diodes, phototransistors, and photocells. Summary of the Invention

[0010] The object of the present invention is to provide novel organic electron-transporting naphthalene-dicarboximide-based and naphthalene-imide-based compounds which contain phosphonic acid or phosphoric acid as an anchoring group, allowing covalent binding to the surface of a transparent conductive oxide at a suitable energy level and minimizing the thickness at low temperatures. Such compounds also more effectively passivate the sensitizer layer (such as perovskite) of a photovoltaic device. Advantageously, compared to the conventionally used SnO2 ETL, the compounds of the present invention, when used in optoelectronic and / or photoelectrochemical devices, simultaneously provide multiple benefits of reduced optical reflectivity and energy loss. In addition, the compounds of the present invention can be directly applied to a TCO substrate (such as an ITO substrate) and can be used as an alternative to a conventional metal oxide (i.e., SnO2, ZnO, and TiO2) ETL or in place of a conventional metal oxide ETL, for example, in an n-i-p PSC.

[0011] The present invention also provides novel electron-transporting materials which provide higher power conversion efficiency and stability.

[0012] Other aspects and preferred embodiments are detailed below and in the appended claims. From the description of the preferred embodiments given below, other features and advantages will become apparent to those skilled in the art. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 a) shows a schematic diagram of a mesoporous n-i-p PSC device structure; b) a planar n-i-p PSC device structure; c) a p-i-n PSC device structure.

[0014] Figure 2a ) shows the UV-visible spectrum of the electron-transporting SAM material V1264; b) shows the UV-visible transmission spectra of the electron-transporting material V1264 and SnO2 on an ITO substrate; c) shows the UV-visible reflection spectra of the electron-transporting material V1264 and SnO2 on an ITO substrate.

[0015] Figure 3 Shows the TGA heating curve (scan rate 10 °C / min, N2 atmosphere) of the first and second heating curves of the electron-transporting material V1264 by DSC.

[0016] Figure 4 Shows the redox voltammogram of the electron-transporting material V1264.

[0017] Figure 5 Shows the water contact angles of ITO and ITO / V1264.

[0018] Figure 6a) Top view of SEM image of perovskite on bare ITO; b) Top view of SEM image of perovskite on V1264 surface (scale bar 1 μm).

[0019] Figure 7 a) Cross-sectional SEM of bare ITO; b) Cross-sectional SEM of ITO / V1264.

[0020] Figure 8 Schematic diagram of an exemplary PSC device structure is shown.

[0021] Figure 9 J-V characteristics of the ETM SAM compound V1264 in the PSC device are shown.

[0022] Figure 10 External quantum efficiency (EQE) spectra of devices based on ITO / SnO2 and ITO / V1264 are shown.

[0023] Figure 11 shows the statistical distribution of electron-selective SAMs from 25 devices.

[0024] Figure 12 Summary of device efficiencies of electron-selective SAMs and n-i-p devices without ETL from the literature is shown.

[0025] Figure 13 shows the evolution of the normalized PCE of unencapsulated devices based on SnO2-ETL and the electron transport SAM material V1264 at a) room temperature storage and b) 65 °C under nitrogen and dark conditions. Detailed Description

[0026] The main object of the present invention is the new compounds of formula (I), (IV) or (V):

[0027]

[0028] Wherein

[0029] X is selected from -L1-A1, H, NH2, C1-C 10 alkyl, C2-C 10 alkenyl, C2-C 10 alkynyl, C4-C 10 aryl, C4-C 20 alkylaryl, C4-C 20 alkenylaryl and C4-C 20 alkynylaryl, each of which is optionally substituted by C1-C 10 alkyl, C2-C 10 alkenyl, C2-C 10 alkynyl, C1-C 10 heteroalkyl, C4-C 10Aryl, C2-C 10 heteroalkenyl, C2-C 10 heteroalkynyl, C4-C 10 heteroaryl or substituted with one or more heteroatoms selected from N, S, and O;

[0030] R1, R2, R3, R4 are independently selected from H, CN, Cl, Br, F, CF3, NO2, C1-C 20 -alkyl, C 2-20 -perfluoroalkyl, C 5-20 -aryl, C 5-20 -heteroaryl;

[0031] A, A1, A2 are anchoring groups and are independently selected from phosphonic acid, monoalkyl ethers of phosphonic acid, phosphoric acid, monoalkyl ethers of phosphoric acid:

[0032]

[0033] or the structure:

[0034]

[0035] R7 is a C1-C9 alkyl group;

[0036] L, L1 are linking segments and are independently selected from C1-C9 alkylene, C4-C 20 arylene, C4-C 20 heteroarylene, C4-C 20 alkylarylene, C4-C 20 alkenylarylene, C4-C 20 heteroalkylarylene, C4-C 20 heteroalkenylarylene, where the heteroatom is selected from O, N, S, Se, Si, or from the following structures:

[0037]

[0038] In embodiments where the compound of formula (I) contains an X selected from C1-C 10 alkyl, C2-C 10 alkenyl, C2-C 10 alkynyl, the alkyl, alkenyl, alkynyl moieties (if they contain 3 or more carbons) can be straight-chain, branched, or cyclic. In embodiments where the compound of formula (I) contains an X selected from C1-C 10 alkyl, C2-C 10 alkenyl, C2-C 10 alkynyl, C4-C 10 aryl, C4-C 20 alkylaryl, C4-C 20 alkenylaryl and C4-C 20In embodiments of X of alkynylaryl, the alkyl, alkenyl, alkynyl, aryl, alkylaryl, alkenylaryl, alkynylaryl may be unsubstituted or substituted by C1-C 10 alkyl, C2-C 10 alkenyl, C2-C 10 alkynyl, C1-C 10 heteroalkyl, C4-C 10 aryl, C2-C 10 heteroalkenyl, C2-C 10 heteroalkynyl, C4-C 10 heteroaryl or one or more heteroatoms selected from N, S and O.

[0039] In embodiments where the compound of formula (I) contains L, L1 is independently selected from C1-C9 alkylene, C4-C 20 arylene, C4-C 20 heteroarylene, C4-C 20 alkylarylene, C4-C 20 alkenylarylene, C4-C 20 heteroalkylarylene, C4-C 20 heteroalkenylarylene, wherein the heteroatoms are selected from O, N, S, Se, Si, or from the following structures:

[0040]

[0041] The alkylene, arylene, heteroarylene, alkylarylene, heteroalkylarylene (if they contain 3 or more carbon atoms) may be straight-chain, branched-chain or cyclic, for example,

[0042]

[0043] As used herein, the term "alkylene" refers to a saturated divalent hydrocarbon group derived by removing two hydrogen atoms from a straight-chain or branched-chain saturated hydrocarbon, and examples are methylene, ethylene and isopropylidene. Thus, as used herein, "arylene", "heteroarylene", "alkylarylene", "alkenylarylene", "heteroalkylarylene" refer to the corresponding divalent groups derived by removing two hydrogen atoms (aryl, heteroaryl, alkylaryl, alkenylaryl, heteroalkylaryl, respectively). As used herein, in cases where the heteroatom is selected from N, the term "C4-C 20 heteroalkenylaryl" should be understood to include structures such as the following:

[0044]

[0045] In a preferred embodiment, the compound is according to formula (I). In some embodiments, the compound of formula (I) may comprise X which is -L1-A1, where L1 is the same as L and A1 is the same as A; such compounds provide electron-transporting naphthalenediimide-based SAM compounds with a symmetric structure. In other embodiments, the compound of formula (I) comprises X which does not have the same structure as -L-A; such compounds provide electron-transporting naphthalenediimide-based SAM compounds with an asymmetric structure.

[0046] According to another embodiment, the naphthalenediimide-based compound of formula (I) contains phosphonic acid as an anchoring group, allowing covalent binding to the surface of a transparent conductive oxide, and it is an electron-transporting material selected from, but not limited to, compounds according to any one of formulas (1) to (35), (37) to (82).

[0047] In some embodiments, the naphthalenediimide-based compound of formula (I) contains phosphoric acid as an anchoring group, such as the compound of formula (36).

[0048] Symmetric structure of exemplary compounds of formula (I):

[0049]

[0050]

[0051]

[0052]

[0053]

[0054] Asymmetric structure of exemplary compounds of formula (I):

[0055]

[0056]

[0057]

[0058]

[0059]

[0060] In some embodiments, where R2 and R3 or R1 and R4 are the same and are selected from CN, Cl, Br, F, CF3, NO2, C1-C 20 -alkyl, C 2-20 -perfluoroalkyl, C 5-20 -aryl, C 5-20-Heteroaryl compounds of formula (I) are preferred because of the increased electronegativity of the compounds.

[0061] In some embodiments, there are provided compounds of formula (I) wherein each of R1, R2, R3, R4 is H, and / or each of A, A1 is phosphonic acid. In such cases, the compound may further comprise L, L1 which are independently selected from C3-C9 alkylene, C4-C 20 arylene, C4-C 20 heteroarylene, C4-C 20 alkylarylene, C4-C 20 heteroalkylarylene, C4-C 20 heteroalkenylarylene, wherein the heteroatom is selected from O, N, S, Se, Si. In particular, for example, in the case where the compound of formula (I) comprises each of R1, R2, R3, R4, i.e., H, A, A1 is phosphonic acid, L, L1 is not methylene or ethylene.

[0062] In some embodiments, there are provided compounds of formula (I) wherein:

[0063] X is selected from -L1-A1,

[0064] R1, R2, R3, R4 are independently selected from H, CN, Cl, Br, F, CF3, NO2, C1-C 20 -alkyl, C 2-20 -perfluoroalkyl, C 5-20 -aryl, C 5-20 -heteroaryl;

[0065] A, A1, A2 are anchoring groups and are independently selected from phosphonic acid, monoalkyl ethers of phosphonic acid, phosphoric acid, monoalkyl ethers of phosphoric acid:

[0066]

[0067] or the structure:

[0068]

[0069] R7 is a C1-C9 alkyl group;

[0070] L, L1 are linking segments and are independently selected from C1-C9 alkylene, C4-C 20 arylene, C4-C 20 heteroarylene, C4-C 20 alkylarylene, C4-C 20 alkenylarylene, C4-C 20 heteroalkylarylene, C4-C 20 heteroalkenylarylene, wherein the heteroatom is selected from O, N, S, Se, Si, or from the following structures:

[0071]

[0072] In some embodiments, such compounds comprise A, A1, A2, i.e., phosphonic acid.

[0073] In some embodiments, such compounds comprise A, A1, i.e., phosphoric acid.

[0074] In some embodiments, when the compound of formula (I) comprises X selected from -L1-A1, the linking segments L and L1 are the same.

[0075] In some embodiments, the compound of formula (I) comprises X, i.e., -L1-A1,

[0076] R1, R2, R3, R4 are independently selected from H, CN, Cl, Br, F, CF3, NO2, C1-C 20 -alkyl, C 2-20 -perfluoroalkyl, C 5-20 -aryl, C 5-20 -heteroaryl,

[0077] The linking segments L and L1 are the same and are selected from C1-C9 alkylene, C4-C 20 arylene, C4-C 20 heteroarylene, C4-C 20 alkylarylene, C4-C 20 alkenylarylene, C4-C 20 heteroalkylarylene, C4-C 20 heteroalkenylarylene, wherein the heteroatom is selected from O, N, S, Se, Si, or from the following structures:

[0078]

[0079] And the anchoring A, A1, A2 anchoring groups are the same and are phosphonic acid. Exemplary compounds of such structures are the compounds of structures 1 to 39, preferably, the compounds of structures 5 to 39.

[0080] In a further embodiment, there is provided a compound of formula (I) wherein X is selected from H, NH2, C1-C 10 alkyl, C2-C 10 alkenyl, C2-C 10 alkynyl, C4-C 10 aryl, C4-C 20 alkylaryl, C4-C 20 alkenylaryl and C4-C 20 alkynylaryl, each of which is optionally substituted by C1-C 10 alkyl, C2-C 10Alkenyl, C2-C 10 Alkynyl, C1-C 10 Heteroalkyl, C4-C 10 Aryl, C2-C 10 Heteroalkenyl, C2-C 10 Heteroalkynyl, C4-C 10 Substituted with a heteroaryl or one or more heteroatoms selected from N, S, and O. Such compounds may have the additional advantage of increased solubility in organic solvents and are thus more convenient to use. Exemplary compounds of such structures are the compounds of Structures 40 to 78.

[0081] In some embodiments, compounds of Formula (I) are provided, wherein X is selected from C4-C optionally substituted with C1-C 10 alkyl-substituted C4-C 20 alkylaryl. When used in a photovoltaic device, such compounds can provide improved interaction with the sensitizer layer of the photovoltaic device. For example, such compounds may have structures as provided in Structures 41, 43, 45, 47, 49, 51, 59, 61, 63, 64, 66, 72.

[0082] Tables 1 and 2 provide some additional non-limiting examples of the compounds of Formula (I) of the present invention.

[0083] Table 1. Examples of Symmetric Compounds of Formula (I) of the Present Invention

[0084]

[0085]

[0086] Table 2. Examples of Asymmetric Compounds of Formula (I) of the Present Invention

[0087]

[0088]

[0089]

[0090] In Tables 1 and 2, the rows numbered with specific numbers represent exemplary compounds or groups of compounds of Formula (I), wherein X, R1, R2, R3, R4, A, A1, A2, L, L1 have specific values. For example, row "No. 90" shows a compound of Formula (I) wherein R1 and R4 are both H, R2 and R3 are both F, A, A1, A2 are phosphonic acids, and L, L1 are the same and are selected from C1-C9 alkylene, C4-C 20 arylene, C4-C 20 heteroarylene, C4-C 20 alkylarylene, C4-C 20Heteroalkylarylene, C4-C 20 Heteroalkenylarylene, wherein the heteroatom is selected from O, N, S, Se, Si or a structure.

[0091] Similarly, it should be understood that, for example, the line "No. 150" represents such a compound wherein X is 2-ethylhexyl, R1 and R4 are both H, R2 and R3 are both phenyl, A, A2 are phosphonic acids, and L, L1 are the same and are selected from C1-C9 alkylene, C4-C 20 Arylene, C4-C 20 Heteroarylene, C4-C 20 Alkylarylene, C4-C 20 Heteroalkylarylene, C4-C 20 Heteroalkenylarylene, wherein the heteroatom is selected from O, N, S, Se, Si or a structure.

[0092] Examples of the structure of the compound of formula (IV) or (V):

[0093]

[0094] In yet another embodiment, the present invention provides an electron transport material comprising one or more of the above-mentioned compounds of formula (I). The compound of the general formula (I) is used as an organic non-polymeric semiconductor. More specifically, the present invention provides an electron transport material comprising at least one compound of formula (I).

[0095] In some embodiments, a composition comprising one or more compounds of formula (I) is provided.

[0096] In another embodiment, the present invention provides an electron transport material comprising one or more of the above-mentioned compounds of formula (IV) or (V). In some embodiments, a composition comprising one or more compounds of formula (IV) or (V) is provided.

[0097] In some embodiments, the composition further comprises a filler molecule (FM), wherein FM is at least one molecule consisting of an anchoring group, an alkyl chain of N carbon atoms, N being 1-18, and at least one functional group selected from methyl, halogen, amino, bromo, ammonium and sulfate functional groups.

[0098] In another embodiment, a optoelectronic and / or photoelectrochemical device comprising an electron transport layer is provided, the electron transport layer comprising a compound of formula (I). In other embodiments, a optoelectronic and / or photoelectrochemical device comprising an electron transport layer is provided, the electron transport layer comprising a composition containing one or more compounds of formula (I).

[0099] As provided herein, optoelectronic and / or photoelectrochemical devices can be selected from photovoltaic devices, organic photovoltaic devices, photovoltaic solid-state devices, organic solar cells, solid-state solar cells, perovskite solar cells, tandem solar cells, light-emitting electrochemical cells, and OLEDs. In a p-n heterojunction, a dye-sensitized solar cell can be provided as a further example of such a device.

[0100] In some embodiments, a photovoltaic device comprising an electron transport material containing a compound of formula (I) is a tandem solar cell, preferably wherein the tandem solar cell comprises at least one perovskite solar cell. A tandem solar cell is a photovoltaic device composed of multiple (two or more) stacked photovoltaic sub-cells, which can be separate cells (mechanically stacked) or electrically interconnected and integrated into one device. At least one sub-cell is a perovskite solar cell (based on a perovskite semiconductor). Examples are: perovskite / silicon; perovskite / CIGS; perovskite / perovskite; organic / perovskite, etc. The tandem type, comprising two photovoltaic sub-cells, can be four-terminal, two-terminal, and three-terminal. Due to the optimized and complementary absorption of electromagnetic radiation by different semiconductors, the goal of forming a tandem device is to more efficiently utilize the solar spectrum. As provided herein, the compounds of the present invention or compositions containing the compounds can be used as an electron transport material in at least one of the perovskite sub-cells of a tandem solar cell.

[0101] In some embodiments, the optoelectronic and / or photoelectrochemical device is a photovoltaic device, preferably the device is a photovoltaic cell. In some embodiments, a photovoltaic device, such as a photovoltaic cell, is provided, which comprises a conductive carrier layer covered with an electron transport layer, a sensitizer layer, a hole transport layer, and a counter electrode, wherein the electron transport layer contains a compound according to formula (I). In some embodiments, the electron transport layer contains a composition comprising one or more compounds according to formula (I) and optionally filler molecules. In some embodiments, the optoelectronic and / or photoelectrochemical device is a photovoltaic device, preferably the device is a photovoltaic cell. In some embodiments, a photovoltaic device, such as a photovoltaic cell, is provided, which comprises a conductive carrier layer covered with an electron transport layer, a sensitizer layer, a hole transport layer, and a counter electrode, wherein the electron transport layer contains a compound according to formula (IV) or formula (V). In some embodiments, the electron transport layer contains a composition comprising one or more compounds according to formula (IV) or (V) and optionally filler molecules.

[0102] In some embodiments, the photovoltaic device comprises an electron transport layer composed of a compound according to formula (I). In some embodiments, the photovoltaic device comprises only an electron transport layer composed of a compound according to formula (I). That is, in such a device, an electron transport material or electron transport layer other than the compound of the present invention may not be required. The compound of the present invention can be directly applied to the TCO substrate and can be used as an alternative to a conventional metal oxide (i.e., SnO2, ZnO, and TiO2) ETL or in place of a conventional metal oxide ETL. In some embodiments, the photovoltaic device comprises an electron transport layer composed of a compound according to formula (I). In some embodiments, the electron transport layer is composed of a composition comprising one or more compounds according to formula (I) and optional filler molecules.

[0103] The conductive support layer of the photovoltaic device is preferably substantially transparent. "Transparent" means transparent to at least a portion, preferably a majority, of visible light. Preferably, the conductive support layer is substantially transparent to all wavelengths or types of visible light. In addition, the conductive support layer may be transparent to invisible light such as UV and IR radiation. The conductive support layer preferably functions and / or comprises a current collector that collects the current obtained from the photovoltaic solid-state device. The conductive support layer may comprise a conductive material selected from indium-doped tin oxide (ITO), indium zinc oxide (IZO), fluorine-doped tin oxide (FTO), metals, and / or other conductors, preferably coated on a transparent substrate such as plastic or glass. In this case, the plastic or glass provides the support structure for the layer, and the listed conductive materials provide conductivity. Such support layers are commonly referred to as conductive glass and conductive plastic, respectively, and are preferred conductive support layers according to the present invention.

[0104] According to some embodiments, the sensitizer layer of the photovoltaic device comprises at least one pigment selected from organic, inorganic, organometallic, organic-inorganic pigments, or combinations thereof. The sensitizer is preferably a light-absorbing compound or material. Preferably, the sensitizer is a pigment, and most preferably, the sensitizer is an organic-inorganic pigment.

[0105] According to a preferred embodiment, the electron transport layer comprising the compound of formula (I) is coated with a layer comprising a sensitizer. Preferably, the sensitizer layer comprises an organic-inorganic perovskite.

[0106] In some embodiments, the electron transport layer comprising the compound of formula (IV) or (V) is coated with a layer comprising a sensitizer.

[0107] According to a preferred embodiment, the sensitizer or the sensitizer layer comprises or consists of an organic-inorganic perovskite. The organic-inorganic perovskite is provided under a thin film of a perovskite pigment or a mixed perovskite pigment or a perovskite pigment mixed with other dyes or sensitizers.

[0108] According to another embodiment, the sensitizer layer comprises another pigment in addition to the organic-inorganic perovskite pigment, and the other pigment is selected from organic pigments, organometallic pigments or inorganic pigments.

[0109] According to another embodiment, the optoelectronic and / or photoelectrochemical device is a dye-sensitized solar cell (DSC) comprising a compound of formula (I) as an electron transport material and a pigment as a sensitizer, the pigment being selected from organic pigments, organometallic pigments, inorganic pigments or combinations thereof.

[0110] For the purposes of this specification, the term "perovskite" refers to a "perovskite structure" and does not specifically refer to the perovskite material CaTiO3. For the purposes of this specification, "perovskite" encompasses and preferably relates to any material having the same type of crystal structure as the calcium titanate oxides and materials in which the divalent cation is replaced by two separate monovalent cations. The perovskite structure has the general stoichiometry AMX3, where "A" and "M" are cations and "X" is an anion. The "A" and "M" cations can have a variety of charges, for example, in the original perovskite mineral (CaTiO3), the A cation is divalent and the M cation is tetravalent.

[0111] In another embodiment, the organic-inorganic perovskite layer material comprises a perovskite structure of formula (II):

[0112] AMX3 (II)

[0113] where

[0114] A is an alkali metal ion, preferably Li + , Na + , K + , Rb + , Cs + ; an ammonium or amidinium ion in which one or more hydrogens are replaced by an alkyl or acyl group; said ammonium ions include monoalkylammonium ions, dialkylammonium ions, trialkylammonium ions and tetraalkylammonium ions in which one or more hydrogens are replaced by an alkyl group. Preferably, the substituents are alkyl groups or groups independently selected from C1-C6, preferably methyl or ethyl. Said ammonium ions, N-alkyl amidinium and iminium ions in which one or more hydrogens are replaced by an alkyl group. Preferably, the amidinium or iminium ions are selected from C1-C6 carboxamide groups, preferably formamide or acetamide groups. The hydrogen atoms in the organic cation A can be replaced by a halogen selected from F, Cl, I and Br, preferably F or Cl.

[0115] Preferably, A is Cs + or methylammonium ion (MA + ) or formamidinium ion (FA + ).

[0116] M is a divalent metal cation selected from the group consisting of: Cu 2+ 、Ni 2+ 、Co 2+ 、Fe 2+ 、Mn 2+ 、Cr 2+ 、Pd 2+ 、Cd 2+ 、Ge 2+ 、Sn 2+ 、Pb 2+ 、Eu 2+ 、or Yb 2+ ; preferably Pb 2+ 、Sn 2+ 。

[0117] X is a monovalent anion independently selected from the group consisting of: Cl - 、Br - 、I - 、NCS - 、CN - 、and NCO - ; preferably Cl - 、Br - 、or I - 。X may be the same or different.

[0118] According to a preferred embodiment, examples of organic-inorganic perovskites are: methylammonium lead halides, such as methylammonium lead iodide (CH3NH3PbI3); methylammonium lead mixed halides, such as, CH3NH3PbClI2; formamidinium lead halides, such as, HC(NH2)2PbI3, HC(NH2)2PbBr3 or HC(NH2)2PbCl2I; cesium lead iodide (CsPbI3), cesium tin iodide (CsSnI3).

[0119] In another embodiment, the organic-inorganic perovskite layer material comprises a mixed perovskite structure, wherein A is a mixture of two or more cations as defined above, and X is a mixture of two or more anions as defined above. Preferably, A is a mixture of two cations, M is Pb, and X is a mixture of two anions. Formula (II) can be represented as the following formula (III):

[0120] A 1 1-y A 2 y PbX 1 3-z X 2 z(III)

[0121] Wherein:

[0122] A 1and A 2 is an organic monovalent cation as defined above for A;

[0123] X 1 and X 2 may be the same or different monovalent anions selected from the group consisting of: Clˉ, Brˉ, Iˉ, NCSˉ, CNˉ, and NCOˉ;

[0124] y is in the range between 0.1 and 0.9;

[0125] z is in the range between 0.2 and 2.

[0126] The sensitizer layer is coated with a layer comprising a hole transport layer (HTL), which may include inorganic and / or organic hole transport materials. The inorganic hole transport materials may include at least one selected from nickel oxide (NiO x ), CuSCN, CuCrO2, and CuI.

[0127] The organic hole transport material may include carbazole derivatives, polyarylalkane derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives, fluorene derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, compounds based on aromatic dimethylidine, compounds based on porphyrin, compounds based on phthalocyanine, polythiophene derivatives, polypyrrole derivatives, poly(phenylenevinylene) derivatives, pentacene, coumarin, 6,3-(2-benzothiazolyl)-7-(diethylamino)coumarin, ZnPC (zinc phthalocyanine), CuPC (copper phthalocyanine), TiOPC (titanium oxide phthalocyanine), spiro-MeOTAD (2,2’,7,7’-tetrakis(N,N-di-p-methoxyaniline)-9,9’-spirobifluorene), F16CuPC (copper(II) 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecafluoro-29H,31H phthalocyanine), SubPc (boron subphthalocyanine chloride), and N3 (cis-bis(isothiocyanato)-bis(2,2’-bipyridine-4,4’-dicarboxylic acid)-ruthenium(II)), P3HT (poly[3-hexylthiophene]), MDMO-PPV (poly[2-methoxy-5-(3’,7’-dimethyloctyloxy)]-1,4-phenylenevinylene), MEH-PPV (poly[2-methoxy-5-(2”-ethylhexyloxy)-p-phenylenevinylene]), P3OT (poly(3-octylthiophene)), POT (poly(octylthiophene)), P3DT (poly(3-decylthiophene)), P3DDT (poly(3-dodecylthiophene)), PPV (poly(phenylenevinylene)), TFB (poly(9,9’-dioctylfluorene-co-N-(4-butylphenyl)diphenylamine), polyaniline, spiro-MeOTAD ([2,22’,7,77’-tetrakis(N,N-di-p-methoxyaniline)-9,9,9’-spirobifluorene]), CuSCN, CuI, PCPDTBT (poly[2,1,3-benzothiadiazole-4,7-diyl[4,4-bis(2-ethylhexyl-4H-cyclopenta[2,1-b:3,4-b’]dithiophene-2,6-diyl]]), Si-PCPDTBT (poly[(4,4’-bis(2-ethylhexyl)dithieno[3,2-b:2’,3’-d]silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl]), PBDTTPD (poly(4,8-diethylhexyloxy)), PFDTBT (poly[2,7-(9-(2-ethylhexyl)-9-hexylfluorene)-alt-5,5-(4’,7-di-2-thienyl-1,2’,1’,3’-benzothiadiazole)]), PFO-DBT (poly[2,7-,9,9-(dioctylfluorene)-alt-5,5-(4’,7’-Di-2-thienyl-2’,1’,3’-benzothiadiazole), PSiFDTBT (poly[(2,7-dioctylsilicon fluorene)-2,7-diyl-(4,7-bis(2-thienyl)-2,1,3-benzothiadiazole)-5,5’-diyl]), PCDTBT (poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophene diyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophene diyl]), PFB (poly(9,9’-dioctylfluorene co-bis(N,N’-(4-butylphenyl))bis(N,N’-phenyl-1,4-phenylene) diamine), F8BT (poly(9,9’-dioctylfluorene co-benzothiadiazole), PEDOT (poly 3,4-ethylenedioxythiophene), PEDOT:PSS poly(3,4-ethylenedioxythiophene) poly(styrenesulfonic acid), PTAA (poly(triarylamine)), 2-PACz, and / or MeO-2PACz, 4-PACz.,

[0128] The present invention also provides a method for preparing an electron transport layer using the compound of the present invention. Various methods can be used to form and produce an electron transport layer containing one or more compounds of the present invention. Suitable coating methods for providing a thin layer of a single-layer electron transport layer can be selected from various solution-based coating methods disclosed herein, for example, as described below.

[0129] A spin coating method for forming a self-assembled monolayer on a TCO substrate, for example, for a perovskite solar cell, may comprise the following steps:

[0130] 1) Provide a substrate covered with an oxide layer (TCO); for example, provide a glass substrate covered with ITO (i.e., a conductive support layer);

[0131] 2) Optionally clean the substrate covered with the oxide layer by sonication; for example, sonication can be carried out in a sonication bath in acetone and / or isopropyl alcohol (IPA); for example, sonication can be carried out for 15 min;

[0132] 3) Optionally treat the substrate covered with TCO with UV ozone or plasma treatment; for example, the treatment can be applied for 15 minutes;

[0133] 4) Provide a solution containing a solvent and a compound according to formula (I); for example, a solution of a compound of formula (I) dissolved in chlorobenzene at a concentration of 0.1 mg / ml to 10 mg / ml can be used, and preferably a solution at a concentration of about 1 mg / ml can be used;

[0134] 5) Spin coat the compound according to Figure (I) in solution on the substrate; for example, by rotating at 5,000 r.p.m for 30 s;

[0135] 6) Heat anneal the compound to the TCO-coated substrate; for example, by heating for a period of 10 minutes to 60 minutes, preferably 10 minutes, at 100 °C;

[0136] 7) Optionally, wash the resulting coated substrate; the washing is carried out to remove unbound molecules, for example, by dynamically spin-coating for 30 s at 5,000 r.p.m. with a solvent for washing.

[0137] In a preferred embodiment, the spin-coating method for forming a self-assembled monolayer on a TCO substrate includes step 3) treating the TCO-coated substrate with UV ozone or plasma treatment.

[0138] The dipping / immersion method for forming a self-assembled monolayer on a TCO substrate, for example for perovskite solar cells, may comprise the following steps:

[0139] 1) Provide a substrate coated with an oxide layer (TCO); for example, provide a glass substrate coated with ITO (i.e., a conductive support layer);

[0140] 2) Optionally clean the oxide layer-coated substrate by sonication; for example, sonication can be carried out in a sonication bath in acetone and / or isopropyl alcohol (IPA); for example, sonication can be carried out for 15 min;

[0141] 3) Optionally treat the TCO-coated substrate with UV ozone or plasma treatment; for example, the treatment can be applied for 15 minutes;

[0142] 4) Provide a solution containing a solvent and a compound according to formula (I); for example, a solution of a compound of formula (I) at a concentration of 0.1 mg / ml to 10 mg / ml dissolved in chlorobenzene can be used, preferably a solution at a concentration of about 1 mg / ml can be used;

[0143] 5) Immerse the TCO-coated substrate in a solution containing a compound according to formula (I); for example, the immersion can be carried out for 10 min to 24 hours, preferably about 1 hour;

[0144] 6) Heat anneal the compound to the TCO-coated substrate; for example, by heating for a period of 10 minutes to 60 minutes, preferably 10 minutes, at 100 °C;

[0145] 7) Optionally, wash the resulting coated substrate; the washing is carried out to remove unbound molecules, for example, by dynamically spin-coating for 30 s at 5,000 r.p.m. with a solvent for washing.

[0146] In a preferred embodiment, the dipping / immersion method for forming a self-assembled monolayer on a TCO substrate includes step 3) treating the TCO-coated substrate with UV ozone or plasma treatment.

[0147] Other solution-based coating methods can be applicable to form self-assembled monolayers on TCO substrates, such as spray coating, slot-die coating, inkjet printing, doctor-blading, screen printing, etc. When used, these methods may include the same steps as the spin coating method provided above, characterized by performing spray coating, slot-die coating, inkjet printing, doctor-blading, or screen printing steps respectively depending on the method used instead of the spin coating step.

[0148] Once a self-assembled monolayer (SAM) is formed on a TCO substrate by the method as described above, other steps of thermal annealing (e.g., about 5 minutes at 80 °C) can be carried out to remove the solvent.

[0149] Alternatively, a SAM can be formed on a TCO substrate by thermal evaporation. For example, the evaporation can be carried out in a thermal evaporation system, where the formed SAM film can be deposited at a rate of -6 at a pressure of ≈5×10 -1 mbar, and can be carried out at a rate of up to

[23] . Then, a 1-step spin coating procedure (e.g., 3,000 rpm, 40 s) can be used and the thermally annealed or evaporated film can be washed with ethanol, for example.

[0150] In some embodiments, a method of forming a self-assembled monolayer on a TCO substrate, such as for a perovskite solar cell, may include the step of simultaneously forming a SAM ETL comprising a compound of formula (I) and a perovskite layer. In such a method, for example, a single treatment step using a single solution containing two additives - a compound of formula (I) and a perovskite precursor can form the SAM layer and the perovskite layer. The method may include, for example, the following steps:

[0151] 1) Prepare a solution comprising a perovskite precursor, a solvent, and a compound according to formula (I);

[0152] 2) Apply the solution to a substrate to form a liquid layer on the substrate; and

[0153] 3) Treat the liquid layer to form a perovskite layer adjacent to the first layer containing molecules.

[0154] Examples

[0155] The following provides information on examples of actual embodiments, describing the preparation patterns and properties of exemplary compounds (V1612, V1625, V1486, V1624, V1635). This information is provided for illustrative purposes and not for limitation.

[0156] Example 1 ​

[0157] General synthetic scheme for the compounds of formula (I): The symmetric structure of the naphthalene diimide-based SAM compounds for electron transport.

[0158]

[0159] Scheme 1. Synthetic routes for the symmetric structures of the naphthalene diimide-based SAM compounds V1612, V1625, and V1486 for electron transport.

[0160] The naphthalene diimide-based compounds V1612, V1625, and V1486 for electron transport containing phosphonic acid anchoring groups and corresponding to formula (I) are prepared through the two-step synthetic route shown in Scheme 1.

[0161] The first step is to reflux the commercially available 1,4,5,8-naphthalenetetracarboxylic dianhydride (1a, TCI Europe) or 2,6-dibromo-1,4,5,8-naphthalenetetracarboxylic dianhydride (1b, TCI Europe) with (aminomethyl)phosphonic acid (abcr GmbH) or (aminoethyl)phosphonic acid (abcr GmbH) in acetic acid to form the intermediates 2a-c with symmetric ether groups (Scheme 1). The next step is to hydrolyze the intermediates 2a-c with trimethylsilyl bromide at room temperature (Method A) or under reflux in concentrated hydrochloric acid (Method B). The target products are obtained as beige crystals.

[0162] N,N’-Bis[diethyl(methyl)]-1,4,5,8-naphthalenetetracarboximide diphosphonate (2a):

[0163]

[0164] 1,4,5,8-Naphthalenetetracarboxylic dianhydride (1a, 2 g, 7.45 mmol) and diethyl (aminomethyl)phosphonate (2.68 ml; 16.33 mmol) were refluxed in acetic acid (40 ml) under an argon atmosphere for 12 h. After termination of the reaction (TLC: methanol∶dichloromethane, 7∶243), the reaction mixture was extracted with EtOAc, and the organic layer was dried over anhydrous Na2SO4. The crude product was purified by column chromatography (methanol∶dichloromethane, 5∶245) to give 2a as white crystals (2.87 g, (68%); melting point 248 - 249 °C. 1 H NMR (400 MHz, CDCl3) δ: 8.79 (s, 4H), 4.69 (d, J = 12.7 Hz, 4H), 4.32–4.07 (m, 8H), 1.34 (t, J = 7.0 Hz, 12H) ppm. 1313C NMR (101 MHz, CDCl3) δ: 162.20, 131.48, 126.86, 126.65, 63.00, 62.94, 37.00, 35.46, 16.54, 16.48 ppm. Analysis and calculation of C 24 H 28 N2O 10 P2: C 50.89; H 4.98; N 4.95; Found: C 50.95; H 4.82; N 4.80.

[0165] N,N'-Bis(methyl)-1,4,5,8-naphthalenetetracarboxylic diimide diphosphonic acid (V1612)

[0166]

[0167] Method A. N,N'-Bis[diethyl(methyl)]-1,4,5,8-naphthalenetetracarboxylic diimide (2a, 0.4 g, 0.70 mmol) was dissolved in chloroform (20 ml), and then trimethylsilyl bromide (1.35 ml, 14.1 mmol) was added dropwise. The reaction mixture was stirred at 25 °C under an argon atmosphere for 12 h. After the reaction was completed (TLC: methanol∶dichloromethane (5∶245)), methanol (3 ml) was added and stirring was continued for 3 h. Then, distilled water (30 ml) was added dropwise until a beige precipitate formed, and stirring was continued for 12 h. The precipitate was filtered off and washed with distilled water (20 ml) and THF (10 ml). The product was obtained as beige crystals (0.2 g, 62% yield).

[0168] Method B. N,N'-Bis[diethyl(methyl)]-1,4,5,8-naphthalenetetracarboxylic diimide (2a, 2.87 g, 5.06 mmol) and concentrated hydrochloric acid (80 ml) were refluxed for 24 h. The formed beige solid was filtered off and washed with 100 ml of distilled water and THF (80 ml). 2.22 g (96% yield) of the product as beige crystals was obtained; melting point > 405 °C. Analysis and calculation of C 16 H 12 N2O 10 P2: C 42.31; H 2.66; N 6.17; Found: C 42.22; H 2.5; N 6.05. MS (ESI, pos.mode), m / z: 453 (M - 1).

[0169] Example 2

[0170] N,N'-Bis[diethyl(ethyl)]-1,4,5,8-naphthalenetetracarboxylic diimide diphosphonate (2b)

[0171]

[0172] 1,4,5,8-Naphthalenetetracarboxylic dianhydride (1a, 2g, 7.46 mmol) and diethyl (aminoethyl)phosphonate (2.7 ml; 16.39 mmol) were refluxed in acetic acid (40 ml) under an argon atmosphere for 48 h. After the reaction was terminated (TLC: methanol∶dichloromethane, 7∶243), the reaction mixture was extracted with EtOAc and the organic layer was dried over anhydrous Na2SO4. The crude product was purified by column chromatography (methanol∶dichloromethane, 7∶243) to give a white-tinged yellow crystal (1.9 g, (43%); mp 226-227 °C). 1 1H NMR (400 MHz, CDCl3) δ: 8.75 (s, 4H), 4.49-4.26 (m, 4H), 4.22-4.05 (m, 8H), 2.37-2.05 (m, 4H), 1.34 (t, J = 7.0 Hz, 12H) ppm. 13 13C NMR (101 MHz, CDCl3) δ: 162.61, 131.22, 126.88, 126.70, 62.13, 62.07, 35.26, 25.19, 23.81, 16.60, 16.54 ppm. Anal. Calcd for C 26 H 32 N2O 10 P2: C 52.53; H 5.43; N 4.71; Found: C 52.30; H 5.32; N 4.50.

[0173] N,N'-Bis(ethyl)-1,4,5,8-naphthalenetetracarboximide diphosphonic acid (V1625)

[0174]

[0175] N,N'-Bis[diethyl(ethyl)]-1,4,5,8-naphthalenetetracarboximide (2b, 1.8 g, 3.02 mmol) and concentrated hydrochloric acid (60 ml) were refluxed for 24 h. The beige solid formed was filtered off and washed with 80 ml of distilled water and THF (50 ml). The product was obtained as beige crystals (1.36 g, 93% yield); mp >405 °C. Anal. Calcd for C 18 H 16 N2O 10 P2: C 44.83; H 3.34; N 5.81; Found: C 44.61; H 3.13; N 5.59. MS (ESI, pos. mode), m / z: 481 (M - 1).

[0176] Example 3

[0177] 2,6-Dibromo-N,N’-bis(ethyl(methyl))-1,4,5,8-naphthalenetetracarboxydiimide diphosphonate (2c)

[0178]

[0179] 2,6-Dibromonaphthalene-1,4,5,8-tetracarboxylic dianhydride (1b, 1g, 1.16 mmol) and diethyl (aminomethyl)phosphonate (0.36 ml; 2.20 mmol) were refluxed in acetic acid (20 ml) under an argon atmosphere for 4 h. After the reaction was terminated (TLC: methanol∶dichloromethane, 5∶245), distilled water (200 ml) was poured into the mixture. The red precipitate solid was filtered out and washed with water (100 ml). The crude product was purified by column chromatography (methanol∶dichloromethane, 5∶245) to give yellow crystals (0.522 g, (33%); melting point > 405 °C). 1 1H NMR (400 MHz, CDCl3) δ: 9.00 (s, 2H), 4.68 (d, J = 12.8 Hz, 4H), 4.33 - 4.08 (m, 8H), 1.35 (t, J = 7.0 Hz, 12H) ppm. 13 13C NMR (101 MHz, CDCl3) δ: 160.27, 160.04, 139.45, 128.93, 127.86, 125.28, 124.28, 63.06, 63.00, 37.27, 35.73, 16.52, 16.46 ppm. Anal. Calcd for C 24 H 26 Br2N2O 10 P2: C 39.80; H 3.62; N 3.87; Found: C 40.22; H 3.7; N 3.93.

[0180] 2,6-Dibromo-N,N’-bis(ethyl)-1,4,5,8-naphthalenetetracarboxydiimide diphosphonate (V1486)

[0181]

[0182] Dissolve 2,6-dibromo-N,N’-[diethyl(methyl)]-1,4,5,8-naphthalenetetracarboxydiimide diphosphate (2c) (0.522 g, 0.72 mmol) in anhydrous 1,4-dioxane (25 ml), and then add trimethylsilyl bromide (1.9 ml, 12.41 mmol) dropwise. Stir the reaction mixture at 25 °C under an argon atmosphere for 14 h. After the reaction is complete (TLC: methanol∶dichloromethane (5∶245)), add methanol (3.5 ml) and continue stirring for 4 h. Then, add distilled water (50 ml) dropwise until a yellow precipitate forms, and continue stirring for 12 h. Filter the precipitate and wash it with distilled water (50 ml) and THF (20 ml). The product is obtained as yellow crystals (0.336 g, 76% yield). 1 H NMR (400 MHz, DMSO-d6) δ 8.76 (s, 2H), 4.40 (d, J = 12.7 Hz, 4H), 3.56 (s, 2H) ppm. 13 C NMR (101 MHz, DMSO) δ: 159.99, 159.74, 137.38, 127.34, 126.78, 125.63, 124.17, 16.36 ppm. Anal. Calcd for C 16 H 10 Br2N2O 10 P2: C 31.40; H 1.65; N 4.58; Found: C 31.21; H 1.50; N 4.4.

[0183] Example 4

[0184] General synthetic scheme for the compounds of formula (I): Asymmetric structure of naphthalenediimide-based SAM compounds for electron transport.

[0185]

[0186] Scheme 2. Synthetic routes for the asymmetric structures of naphthalenediimide-based SAM compounds V1264 and V1624 for electron transport.

[0187] The electron - transporting naphthalenediimide - based compounds V1264 and V1624 containing phosphonic acid anchoring groups and corresponding to the general formula (I) are prepared via the three - step synthetic route shown in Scheme 2. The first two steps are carried out by a one - pot operation: We first carry out the reaction of commercially available 1,4,5,8 - naphthalenetetracarboxylic dianhydride (1, TCI Europe) and diethyl (aminomethyl) phosphonate or diethyl (aminoethyl) phosphonate (abcr GmbH) in anhydrous DMF at 110 °C, and then carry out the imidization reaction with 2a, b and 2,5 - di - tert - butylaniline to obtain intermediates 3a, b (Scheme 2). The final step is to hydrolyze the phosphonates 3a, b with trimethylsilyl bromide at room temperature (Method A) or hydrolyze the phosphonates 3a, b under reflux in concentrated hydrochloric acid (Method B). The target products are obtained as green - yellow crystals.

[0188] N-(2,5 - Di - tert - butylphenyl)-N’-[diethyl(methyl)] - 1,4,5,8 - naphthalenetetracarboxylic diimide phosphonate (3a)

[0189]

[0190] Dissolve 1,4,5,8 - naphthalenetetracarboxylic dianhydride (1, 0.5 g, 1.86 mmol) in anhydrous DMF (50 ml) and add dropwise diethyl (aminomethyl) phosphonate (0.337 g, 1.86 mmol). Stir the solution and react at 110 °C in a nitrogen atmosphere for 4 hours. Then (TLC: acetone∶n - hexane, 1∶4, developed with 1% ninhydrin solution for TLC), add 2,5 - di - tert - butylaniline (0.458 g, 2.23 mmol), heat the reaction mixture to 140 °C and react for another 24 hours. After the reaction is terminated (TLC: acetone∶n - hexane, 1∶4), extract the reaction mixture with ethyl acetate. Dry the organic layer with anhydrous Na2SO4 and evaporate the solvent under reduced pressure. Obtain the product by column chromatography (acetone∶n - hexane, 1∶4) as a green - yellow powder (0.359 g, 32%); melting point 217 - 218 °C. 1 HNMR(400MHz,CDCl3)δ:8.82(s,4H),7.60(d,J = 8.6Hz,1H),7.48(d,J = 10.8Hz,1H),7.00(s,1H),4.71(d,J = 12.8Hz,2H),4.30 - 4.19(m,4H),1.36(t,J = 7.1Hz,6H),1.32(s,9H),1.26(s,9H)ppm. 1313C NMR (101 MHz, CDCl3) δ: 163.87, 162.33, 150.51, 143.82, 132.09, 131.56, 131.52, 129.13, 127.66, 127.07, 126.82, 126.60, 62.99, 62.93, 36.96, 35.69, 34.41, 31.84, 31.32, 16.55, 16.49 ppm. Analysis and calculation of C 33 H 37 C65.55H6.17N4.63O7P: Calculated: C 65.55; H 6.17; N 4.63; Found: C 65.29; H 5.91; N 4.34.

[0191] N-(2,5-Di-tert-butylphenyl)-N'-(methyl)-1,4,5,8-naphthalenetetracarboxylic diimide phosphonic acid (V1264)

[0192]

[0193] Method I. Dissolve N-(2,5-di-tert-butyl-phenyl)-N'-[diethyl(methyl)]-1,4,5,8-naphthalenetetracarboxylic diimide phosphonate (3a) (0.150 g, 0.24 mmol) in anhydrous 1,4-dioxane (5 ml), and then add trimethylsilyl bromide (0.32 ml, 2.42 mmol) dropwise. Stir the reaction mixture at 25 °C under an argon atmosphere for 12 h. After completion of the reaction (TLC: acetone∶n-hexane (1∶4)), add methanol (1 ml) and continue stirring for 4 h. Then, add distilled water (10 ml) dropwise until a yellow precipitate forms, and continue stirring for 12 h. Filter off the precipitate and wash it with ether (150 ml). The product is obtained as green-yellow crystals (0.096 g, 73% yield).

[0194] Method II. Reflux N-(2,5-di-tert-butylphenyl)-N'-[diethyl(methyl)]-1,4,5,8-naphthalenetetracarboxylic diimide phosphonate (3a) (0.200 g, 0.36 mmol) and concentrated hydrochloric acid (25 ml) for 24 h. Filter off the formed yellow solid and wash it with 200 ml of distilled water. Dissolve the product in THF (50 ml) and recrystallize it from ether (250 ml). Filter off the crystals and wash them with ether (50 ml) to obtain 0.173 g (95% yield) of yellow crystals; melting point 275 - 276 °C. 11H NMR (400 MHz, CDCl3) δ: 8.78 (s, 4H), 7.57 (d, J = 8.6 Hz, 1H), 7.46 (d, J = 10.6 Hz, 1H), 6.99 (s, 1H), 4.53 (s, 2H), 3.49 (s, 1H), 3.48 (s, 1H), 1.26 (s, 9H), 1.22 (s, 9H) ppm. 13 13C NMR (101 MHz, CDCl3) δ: 163.95, 162.73, 150.46, 143.79, 132.13, 131.91, 131.53, 129.11, 127.64, 127.50, 126.80, 126.37, 66.01, 34.38, 31.85, 31.30, 29.84 ppm. Analysis and calculation of C 29 H 29 F5N2O7P: C 63.50; H 5.33; N 5.11; Found: C 63.27; H 5.08; N 4.88. MS (ESI, pos. mode), m / z: 547 (M + H + )

[0195] Example 5

[0196] N-(2,5-Di-tert-butylphenyl)-N'-[diethyl(ethyl)]-1,4,5,8-naphthalenetetracarboxylic diimide phosphonate (3b)

[0197]

[0198] Dissolve 1,4,5,8-naphthalenetetracarboxylic dianhydride (1, 0.5 g, 1.86 mmol) in anhydrous DMF (40 ml) and add dropwise diethyl (2-aminoethyl)phosphonate (0.3 ml, 1.86 mmol). Stir the solution at 110 °C for 4 h in a nitrogen atmosphere. After that (TLC: acetone∶n-hexane, 8∶17), add 2,5-di-tert-butylaniline (0.458 g, 2.23 mmol), heat the reaction mixture to 140 °C and react for another 24 h. After the reaction is terminated (TLC: acetone∶n-hexane, 8∶17), the reaction mixture is extracted with ethyl acetate. The organic layer is dried over anhydrous Na2SO4 and the solvent is evaporated under reduced pressure. The crude product is purified by column chromatography (acetone∶n-hexane, 8∶17) to obtain the product, a beige powder (0.35 g, 30%); melting point 234 - 235 °C. 11H NMR (400 MHz, CDCl3) δ: 8.81 (s, 4H), 7.59 (d, J = 8.6 Hz, 1H), 7.48 (d, J = 8.5 Hz, 1H), 6.99 (s, 1H), 4.57 - 4.42 (m, 2H), 4.27 - 4.06 (m, 4H), 2.36 - 2.22 (m, 2H), 1.37 (t, J = 7.0 Hz, 6H), 1.32 (s, 9H), 1.25 (s, 9H) ppm. 13 13C NMR (101 MHz, CDCl3) δ: 163.91, 162.72, 150.48, 143.80, 131.54, 131.30, 129.12, 127.64, 127.30, 127.18, 127.11, 126.82, 68.10, 62.16, 35.67, 35.24, 34.40, 31.84, 31.32, 25.74, 16.61, 16.55 ppm. Analysis and calculation for C 34 H 39 N2O7P: C 66.01; H 6.35; N 4.53; Found: C 65.91; H 6.26; N 4.55.

[0199] N-(2,5-Di-tert-butylphenyl)-N'-(ethyl)-1,4,5,8-naphthalenetetracarboxylic diimide phosphonic acid (V1624)

[0200]

[0201] N-(2,5-Di-tert-butylphenyl)-N'-[diethyl(ethyl)]-1,4,5,8-naphthalenetetracarboxylic diimide phosphonate (3b) (0.22 g, 0.35 mmol) and concentrated hydrochloric acid (15 ml) were refluxed for 24 h. After the reaction was completed (acetone∶n-hexane, 8∶17), the solvent was evaporated. The crude product was dissolved in THF (60 ml) and recrystallized from diethyl ether (280 ml). The crystals were filtered off and washed with diethyl ether (40 ml) to give yellow crystals (0.19 g, 95% yield); melting point 213 - 214 °C. 1 1H NMR (400 MHz, DMSO-d6) δ: 8.71 (s, 4H), 7.56 (d, J = 8.5 Hz, 1H), 7.45 (d, J = 8.5 Hz, 1H), 7.37 (s, 1H), 4.28 (s, 2H), 2.53 (s, 1H), 2.18 (s, 1H), 2.08 - 1.90 (m, 2H), 1.27 (s, 9H), 1.16 (s, 9H) ppm. 1313C NMR (101 MHz, DMSO-d6) δ: 163.84, 162.46, 143.22, 139.21, 132.92, 130.70, 130.45, 128.27, 128.05, 126.89, 126.63, 126.44, 35.07, 34.40, 34.05, 31.34, 31.04, 30.43 ppm. Analysis and calculation of C 30 H 31 C6H5N2O7P: C 64.05; H 5.55; N 4.98; Found: C 64.20; H 5.39; N 4.81.

[0202] Example 6

[0203] N-(2,5-Di-tert-butylphenyl)-N'-(phenyl)-1,4,5,8-naphthalenetetracarboxylic diimide phosphonate

[0204]

[0205] Dissolve 1,4,5,8-naphthalenetetracarboxylic dianhydride (1, 0.5 g, 1.86 mmol) in anhydrous DMF (40 ml) and add diethyl (4-aminophenyl)phosphonate (0.427 g, 1.86 mmol). Stir the solution at 140 °C for 12 h under a nitrogen atmosphere. Then (TLC: acetone∶n-hexane, 12∶13), add 2,5-di-tert-butylaniline (0.459 g, 2.23 mmol)), heat the reaction mixture to reflux and allow the reaction to proceed for another 12 h. After the reaction is terminated (TLC: acetone∶n-hexane, 9∶16), the reaction mixture is extracted with ethyl acetate. The organic layer is dried over anhydrous Na2SO4 and the solvent is evaporated under reduced pressure. The crude product is purified by column chromatography (acetone∶n-hexane, 9∶16) to give the product, beige crystals (0.131 g, 11%); melting point 165 - 166 °C. 1 1H NMR (400 MHz, CDCl3) δ: 8.87 (s, 4H), 8.11 - 7.93 (m, 2H), 7.61 (d, J = 8.5 Hz, 1H), 7.48 (dd, J = 14.2, 8.2 Hz, 3H), 7.02 (s, 1H), 4.28 - 4.09 (m, 4H), 1.38 (t, J = 7.0 Hz, 6H), 1.33 (s, 9H), 1.28 (s, 9H) ppm. 1313C NMR (101 MHz, CDCl3) δ: 166.95, 163.85, 162.92, 150.56, 143.79, 138.39, 133.31, 133.20, 132.04, 131.74, 131.65, 130.80, 129.18, 129.07, 128.92, 127.63, 127.53, 127.47, 126.86, 62.58, 62.53, 35.71, 34.43, 31.87, 31.33, 30.45, 16.56, 16.49 ppm. Analysis and calculation of C 38 H 39 For C8H11N2O7P: C 68.46; H 5.90; N 4.20; Found: C 68.55; H 5.73; N 4.33.

[0206] N-(2,5-Di-tert-butylphenyl)-N'-(phenyl)-1,4,5,8-naphthalenetetracarboxylic diimide phosphonate (V1635)

[0207]

[0208] N-(2,5-Di-tert-butylphenyl)-N'-(phenyl)-1,4,5,8-naphthalenetetracarboxylic diimide phosphonate (0.1 g, 0.14 mmol) and concentrated hydrochloric acid (15 ml) were refluxed for 24 h. The formed yellow solid was filtered out and washed with 50 ml of distilled water and ether (30 ml) to give 0.081 g of yellow crystals (89% yield); melting point 300 - 301 °C. 1 1H NMR (400 MHz, CDCl3) δ: 8.91 - 8.40 (m, 4H), 8.00 (s, 3H), 7.52 (t, J = 11.1 Hz, 1H), 7.42 (d, J = 8.4 Hz, 2H), 7.04 (s, 1H), 1.21 (s, 18H) ppm. 13 13C NMR (101 MHz, CDCl3) δ: 163.77, 163.09, 150.46, 143.64, 132.03, 131.47, 127.35, 126.81, 35.64, 34.35, 31.88, 31.25 ppm. Analysis and calculation of C 34 H 31 For C8H11N2O7P: C 66.88; H 5.12; N 4.59; Found: C 66.65; H 4.96; N 4.37.

[0209] Example 7

[0210] Absorption spectrum

[0211] In the n-i-p structure PSC, light first passes through the ETL, so it is important to minimize the parasitic absorption of this layer. Through UV / visible light spectroscopy from 10 -4 M anhydrous dichloromethane to study the optical properties of the electron transport SAM compound V1264 ( Figure 2a ). Apparently, there is no obvious absorption in the visible light region. In addition, compared with the bare ITO and ITO / SnO2 films, the UV-visible light transmittance results of the electron transport material SAM functionalization on the ITO surface show negligible optical losses ( Figure 2b , c).

[0212] Example 8

[0213] Thermogravimetric analysis (TGA)

[0214] TGA was carried out on a Q50 thermogravimetric analyzer (TA Instruments) at a scanning rate of 10 K min -1 in a nitrogen atmosphere. It can be seen from Figure 3 that the electron transport SAM compound V1264 has a 95% weight loss temperature of 356 °C, which is suitable for practical applications in optoelectronic devices.

[0215] Example 9

[0216] Cyclic voltammetry (CV)

[0217] CV measurements were carried out by a three-electrode assembled cell from Bio-Logic SP-150. Measurements were carried out on a glassy carbon electrode in a solution of DMF and DCM containing 0.1 M tetrabutylammonium hexafluorophosphate as the electrolyte, Pt as the counter electrode and as the reference electrode. Each measurement was calibrated with ferrocene (Fc) and the potential was calculated as Fc + / Fc. Conversion factors: ferrocene in DCM is 0.46 relative to SCE, in DMF is 0.45 relative to SCE, SCE relative to SHE: 0.244, SHE relative to vacuum: 4.43 (N.G. Connelly, W.E. Geiger, Chemical Reviews 1996, 96, 877; V.V. Pavlishchuk, A.W. Addison, Inorganica Chimica Acta 2000, 298, 97). The half-wave potential E 1 / 2vs Fc is obtained as the average between the maximum values of the cathode and anode potentials: E 1 / 2vs Fc = 1 / 2(E red - E ox ). The optical band gap is estimated from the edge of the electron absorption spectra in DCM and DMF solutions E LUMO from the equation E LUMO= (Evs Fc / Fc + + (solvent vs SCE) + 0.244 + 4.43 calculated. E HOMO From the equation E HOMO = E LUMO + E gopt calculated.

[0218] The voltammogram of V1264 in solution shows a reversible reduction wave during the scan and is typical for NDI derivatives ( Figure 4 ). The reversible process indicates that the material exhibits good electrochemical stability. The calculated energy level redox potential measurements show that the E LUMO level of V1264 is measured to be -3.81 eV, while E HOMO = -6.97 eV (Table 1). The E LUMO of the electron transport compound shows a good alignment with the conduction band maximum of the perovskite absorber, while the E HOMO energy level is high enough to block holes from the perovskite layer.

[0219] Table 3. Energy levels of electron transport SAM compounds.

[0220]

[0221] Example 10

[0222] Characterization of the ITO / NDI-SAM surface: Contact angle measurement, SEM images

[0223] Relative to bare ITO at about 28.5°, the electron transport molecule V1264 coated on ITO significantly increases the surface hydrophobicity of the ITO substrate to about 78.4° ( Figure 5 ). Note that all samples were washed with their respective solvents to remove unbound SAM molecules from the ITO substrate. This reveals that attaching only the SAM to the ITO will affect the surface hydrophobicity, which can be directly related to the coverage of our SAM on the ITO.

[20] The higher hydrophobicity of the ITO / SAM substrate will affect the crystallization and morphology of the perovskite film. [21,22] The more hydrophobic surface (less wettable) of the ITO / NDI-SAM can suppress the drag force of the perovskite ink, resulting in larger-sized perovskite crystals, as shown in the top-view scanning electron microscopy (SEM) images in Figure 6 a, b. [21,22] In addition, the tert-butyl group of V1264 on the upper side can interact well with the perovskite layer, resulting in fewer pinholes or voids formed at the ITO / V1264 / perovskite interface, see Figure 7 .

[0224] The contact potential difference (CPD) values of V1264 mapped the surface of ITO, confirming the uniformity of SAM coverage. The fairly uniform pattern is proportional to the narrow work function (WF) fluctuations in the specific surface area (~4.45 eV), generally indicating good V1264 coverage on ITO.

[0225] Example 11

[0226] Photovoltaic cell fabrication and performance measurement

[0227] The performance of the electron transport self-assembled monolayer compound V1264 was tested in a hybrid perovskite-based solar cell using an ITO photoanode and an Ag cathode (ITO / V1264 / hybrid perovskite / HTL / MoOx / Ag) ( Figure 8 ).

[0228] Device fabrication: The patterned ITO / glass substrates were cleaned in an ultrasonic bath in acetone and isopropyl alcohol (IPA) for 15 minutes each, followed by a 15-minute UV ozone treatment for surface cleaning and increasing the oxygen concentration. Then, 0.5 - 1.0 mg / mL of V1264 was dissolved in chlorobenzene. The SAM solution was coated on ITO / glass by spin-coating at 5,000 r.p.m for 30 s, followed by a 10-minute thermal annealing at 100 °C. After cooling, the SAM film was washed with chlorobenzene to remove unbound molecules by dynamic spin-coating at 5,000 r.p.m for 30 s. Subsequently, it was thermally annealed at 80 °C for 5 minutes to evaporate the remaining solvent. Based on the formula Cs 0.03 (FA 0.90 MA 0.10 ) 0.97PbI3, diluting a perovskite solution (1.5 M) with a 1.55 eV bandgap composed of a triple A-site cation mixture in DMF∶DMSO (4∶1 v / v ratio) (S.-K. Jung, J.H. Heo, D.W. Lee, S.-C. Lee, S.-H. Lee, W. Yoon, H. Yun, S.H. Im, J.H. Kim, O.-P. Kwon, Advanced Functional Materials 2018, 28, 1800346). Thus, the perovskite solution was applied to the SAM film by two-step spin-coating, where it was spun at 2,000 r.p.m. for 40 s and then at 6,000 r.p.m. for 10 s to form a perovskite film. Solvent quenching using anisole (300 μl) was applied as a standard procedure during the last 10 s of spin-coating the substrate, followed by annealing at 100 °C for 40 min. After cooling, the HTL was spin-coated on top of the perovskite film at 4000 r.p.m. for 35 s without additional annealing. The organic HTL was prepared by dissolving 72.3 mg of spiro-OMeTAD, 28.8 μl of tBP, and 17.5 μl of LiTFSI in 1 mL of chlorobenzene. Then, at 10 -6 Torr vacuum, 5 nm of MoO x and 100 nm of Ag were thermally evaporated, and the metal mask area was approximately 0.1 cm 2 to define the active area of the device.

[0229] n-i-p PSCs with pristine SnO2 were used for comparison. SnO2 was prepared as follows: The patterned ITO / glass substrates were cleaned in an ultrasonic bath in acetone and isopropyl alcohol (IPA) for 15 min each, followed by UV ozone treatment for 15 min for surface cleaning and increasing the oxygen concentration. Then, an SnO2 layer was prepared by spin-coating a colloidal dispersion of SnO2 (15%, in H2O, Alfa Aesar) diluted with deionized water (1:4 v / v ratio) on the ITO substrate (4000 rpm, 35 s), and then annealing at 150 °C for 25 min.

[0230] Device characterization: The fabricated perovskite photovoltaic cells were evaluated by photocurrent density-voltage (J-V) characteristics. The J-V characteristics of the device performance were measured in a stable N2-purged glove box under an Abet Technologies Sun 3000 solar simulator equipped with a Keithley 2400 source unit. The light source was calibrated to AM 1.5G (100 mW cm 2 ) using a single-crystalline silicon standard cell (Newport). Forward and reverse scans were performed on all devices at a scan rate of 100 mV s -1, a 30 s light soaking treatment was performed before each measurement. The external quantum efficiency (EQE) spectra were organized by a monochromator and a filter in an N2 glove box on an optical test board equipped with a 400 W xenon lamp and calibrated to 603621 silicon and germanium reference detectors. Capacitance-voltage measurements were performed to obtain the capacitance with a scanning frequency from 1 MHz to 1 Hz (10 mV AC voltage). The voltage was varied from 0 to 1.2 V at a constant frequency of 1 kHz.

[0231] The ETM self-assembled monolayer compound V1264 exhibited higher device performance under reverse scan, with a maximum PCE of 21.5% (V OC being 1.13 V, J SC being 24.7 mA cm -2 , and FF being 77%), with negligible hysteresis ( Figure 9 ). The external quantum efficiency (EQE) of the devices based on V1264 showed a slightly higher total J SC than that of the devices based on SnO2, because of the higher absorption at the EQE edge due to the lower optical reflectance loss of the ITO / V1264 film. The statistical distribution of the electron-selective SAMs from 25 devices is shown in (Figure 11), which shows the reproducibility of the V1264-based devices with a narrow PCE distribution. This result represents a higher performance of the electron-selective SAM and ETL-free based on the reported n-i-p PSC ( Figure 12 ).

[0232] Example 12

[0233] Long-term stability test of photovoltaic cells

[0234] First, the devices based on SnO2-ETL and SAM molecule V1264 were stored in an N2-glove box at room temperature for 1000 h, and the devices were occasionally measured ( Figure 13a ). The SnO2-based n-i-p devices could only retain about 58% of their initial PCE after 1000 h of storage, while the devices based on V1264 showed a longer lifetime with about 84% retention.

[0235] Next, we also evaluated the thermal stability of the photovoltaic devices on a hot plate under dark conditions at 65 °C in an N2-glove box for more than 1000 h, and compared the SAM molecule-based V1264 and SnO2-based devices in Figure 13b . It was clearly shown that the devices based on SAM molecule V1264 exhibited better thermal stability compared to the SnO2-based devices that only retained about 38% under the same conditions, with about 72% retention of their initial PCE.

[0236] It should be noted that the degradation of n-i-p devices can also be triggered by the doped spiro-OMeTAD HTL at elevated temperatures. [7,12] To this end, we also used a relatively thermally stable HTL and evaluated devices based on the SAM molecule V1264 using poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), which showed more than 90% retention under the same conditions.

[0237] Example 13

[0238] Table 4. Solubility of various compounds

[0239]

[0240]

[0241] Example 14

[0242] Other aspects of the present disclosure are illustrated by the following numbered clauses:

[0243] Clause 1. A compound of formula (I), (IV), (V):

[0244]

[0245] Wherein

[0246] X is selected from -L1-A1, H, NH2, C1-C 10 alkyl, C2-C 10 alkenyl, C2-C 10 alkynyl, C4-C 10 aryl, C4-C 20 alkylaryl, C4-C 20 alkenylaryl and C4-C 20 alkynylaryl, each of which is optionally substituted by C1-C 10 alkyl, C2-C 10 alkenyl, C2-C 10 alkynyl, C1-C 10 heteroalkyl, C4-C 10 aryl, C2-C 10 heteroalkenyl, C2-C 10 heteroalkynyl, C4-C 10 heteroaryl or one or more heteroatoms selected from N, S, and O;

[0247] R1, R2, R3, R4 are independently selected from H, CN, Cl, Br, F, CF3, NO2, C1-C 20 -alkyl, C 2-20 -perfluoroalkyl, C 5-20 -aryl, C5-20 - heteroaryl;

[0248] A, A1, A2 are independently selected from phosphonic acid, monoalkyl ether of phosphonic acid, phosphoric acid, monoalkyl ether of phosphoric acid:

[0249]

[0250] or the structure:

[0251]

[0252] R7 is a C1-C9 alkyl group;

[0253] L, L1 are independently selected from C1-C9 alkylene, C4-C 20 arylene, C4-C 20 heteroarylene, C4-C 20 alkylarylene, C4-C 20 alkenylarylene, C4-C 20 heteroalkylarylene, C4-C 20 heteroalkenylarylene, wherein the heteroatom is selected from O, N, S, Se, Si, or from the following structures:

[0254]

[0255] Clause 2. The compound according to Clause 1, wherein the compound is a compound of formula (I).

[0256] Clause 3. The compound according to Clause 1 or 2, wherein when each of R1, R2, R3, R4 is H, and each of A, A1 is phosphonic acid, then L, L1 are independently selected from C3-C9 alkylene, C4-C 20 arylene, C4-C 20 heteroarylene, C4-C 20 alkylarylene, C4-C 20 heteroalkylarylene, C4-C 20 heteroalkenylarylene, wherein the heteroatom is selected from O, N, S, Se, Si, or from the following structures:

[0257]

[0258] Clause 4. The compound according to any one of the preceding clauses, wherein A, A1 and A2 are phosphonic acid.

[0259] Clause 5. The compound according to any one of the preceding clauses, wherein L and L1 are the same.

[0260] Clause 6. The compound according to any one of the preceding clauses, wherein X is -L1-A1.

[0261] Clause 7. The compound according to any one of Clauses 1 to 4, wherein X is selected from H, NH2, C1-C 10 alkyl, C2-C 10 alkenyl, C2-C 10 alkynyl, C4-C 10 aryl, C4-C 20 alkylaryl, C4-C 20 alkenylaryl and C4-C 20 alkynylaryl, each of which is optionally substituted by C1-C 10 alkyl, C2-C 10 alkenyl, C2-C 10 alkynyl, C1-C 10 heteroalkyl, C4-C 10 aryl, C2-C 10 heteroalkenyl, C2-C 10 heteroalkynyl, C4-C 10 heteroaryl or one or more heteroatoms selected from N, S, and O.

[0262] Clause 8. The compound according to Clause 7, wherein X is selected from C4-C optionally substituted by C1-C 10 alkyl-substituted C4-C 20 alkylaryl.

[0263] Clause 9. A composition comprising one or more compounds according to any one of the preceding clauses.

[0264] Clause 10. The composition according to Clause 9, further comprising a filler molecule (FM), wherein FM is at least one molecule consisting of an anchoring group, an alkyl chain of N carbon atoms, N being 1-18, and at least one functional group selected from methyl, halogen, amino, bromo, ammonium, and sulfate functional groups.

[0265] Clause 11. A optoelectronic and / or photoelectrochemical device comprising an electron transport layer, the electron transport layer comprising a compound according to any one of Clauses 1 to 8 or a composition according to Clause 9 or 10.

[0266] Clause 12. The optoelectronic and / or photoelectrochemical device according to Clause 11, wherein the device is selected from photovoltaic devices, organic photovoltaic devices, photovoltaic solid-state devices, organic solar cells, solid-state solar cells, perovskite solar cells, tandem solar cells, light-emitting electrochemical cells, and OLEDs.

[0267] Clause 13. The optoelectronic and / or photoelectrochemical device according to Clause 12, wherein the device is a photovoltaic device.

[0268] Clause 14. The photovoltaic device according to Clause 13, comprising a conductive support layer covered with an electron transport layer, a sensitizer layer, a hole transport layer, and a counter electrode, wherein the electron transport layer comprises the compound according to any one of Clauses 1 to 8 or the composition according to Clause 9 or 10.

[0269] Clause 15. The photovoltaic device according to Clause 14, wherein the electron transport layer consists of the compound according to any one of Clauses 1 to 8 or the composition according to Clause 9 or 10.

[0270] Clause 16. The photovoltaic device according to any one of Clauses 12 to 15, wherein the device is a tandem solar cell, preferably wherein the tandem solar cell comprises at least one perovskite solar cell.

[0271] Clause 17. The photovoltaic device according to any one of Clauses 14 to 16, wherein the sensitizer layer comprises an organic-inorganic perovskite.

[0272] Clause 18. The photovoltaic device according to Clause 17, wherein the organic-inorganic perovskite is a perovskite-type structure of formula (II):

[0273] AMX3 (II)

[0274] Wherein:

[0275] A is an alkali metal ion, preferably Li + , Na + , K + , Rb + , Cs + ; ammonium or amidinium ion, wherein one or more hydrogens are replaced by alkyl or acyl groups;

[0276] M is a divalent metal cation selected from the group consisting of: Cu 2+ , Ni 2+ , Co 2+ , Fe 2+ , Mn 2+ , Cr 2+ , Pd 2+ , Cd 2+ , Ge 2+ , Sn 2+ , Pb 2+ , Eu 2+ , or Yb 2+ ;

[0277] X is a monovalent anion independently selected from the group consisting of: Cl - , Br - , I - , NCS - , CN- , and NCO - ;

[0278] Clause 19. The photovoltaic device according to Clause 18, wherein the organic-inorganic perovskite is a mixed perovskite-type structure according to formula (III):

[0279] A 1 1-y A 2 y PbX 1 3-z X 2 z(III)

[0280] Wherein:

[0281] A 1 and A 2 are independently selected from Li + , Na + , K + , Rb + , Cs + ammonium or amidinium ions of organic monovalent cations; wherein one or more hydrogens of the ammonium or amidinium ions are substituted by alkyl or acyl or halogen;

[0282] X 1 and X 2 are the same or different monovalent anions selected from Cl - , Br - , I - , NCS - , CN - , and NCO - ;

[0283] y is in the range between 0.1 and 0.9; and

[0284] z is in the range between 0.2 and 2.

[0285] Clause 20. The photovoltaic device according to any one of Clauses 14 to 19, wherein the conductive support layer comprises a conductive material selected from indium-doped tin oxide (ITO), indium zinc oxide (IZO), fluorine-doped tin oxide (FTO), metal, and / or other conductors.

[0286] According to the grant agreement No. 101082176 of the VALHALLA project, the Horizon Europe Research and Innovation Action program provided financial support for the research work of this project.

[0287] Reference document

[0288] [1]Best Research-cell Efficiencies Chart,https: / / www.nrel.gov / pv / assets / pdfs / best-research-cell-efficiencies.pdf

[0289] [2]L.Chao,T.Niu,W.Gao,C.Ran,L.Song,Y.Chen,W.Huang,Adv.Mater.2021,33,2005410.

[0290] [3]F.Fu,J.Li,T.C.Yang,H.Liang,A.Faes,Q.Jeangros,C.Ballif,Y.Hou,Adv.Mater.2022,34,2106540.

[0291] [4]J.Y.Kim,J.W.Lee,H.S.Jung,H.Shin,N.G.Park,Chem Rev,2020,120:7867–7918.

[0292] [5]H.Min,M.Kim,S.-U.Lee,H.Kim,G.Kim,K.Choi,J.H.Lee,S.I.Seok,Science2019,366,749.

[0293] [6]H.Si,X.Zhao,Z.Zhang,Q.Liao,Y.Zhang,Coordination ChemistryReviews2024,500:215502.

[0294] [7]Y.Yao,C.Cheng,C.Zhang,H.Hu,K.Wang,S.De Wolf,Adv.Mater.2022,34,2203794.

[0295] [8]C.E.Puerto Galvis,D.A.Gonzalez Ruiz,E.Martinez-Ferrero,E.Palomares,Chem.Sci.2023,DOI:10.1039 / d3sc04668k

[0296] [9]A.Al-Ashouri,A.Magomedov,M.Ross,M.Jost,M.Talaikis,G.Chistiakova,T.Bertram,J.A.Márquez, E. Kasparavicius, S. Levcenco, L. Gil-Escrig, C. J. Hages, R. Schlatmann, B. Rech, T. Malinauskas, T. Unold, C. A. Kaufmann, L. Korte, G. Niaura, V. Getautis, S. Albrecht, Energy & Environmental Science 2019, 12, 3356.

[0297]

[10] Q. Tan, Z. Li, G. Luo, X. Zhang, B. Che, G. Chen, H. Gao, D. He, G. Ma, J. Wang, J. Xiu, H. Yi, T. Chen, Z. He, Nature 2023.

[0298]

[11] D. Meng, J. Xue, Y. Zhao, E. Zhang, R. Zheng, Y. Yang, Chemical Reviews 2022, 122, 14954.

[0299]

[12] R. Azmi, S. Zhumagali, H. Bristow, S. Zhang, A. Yazmaciyan, A. R. Pininti, D. S. Utomo, A. S. Subbiah, S. De Wolf, Advanced Materials 2023, 2211317.

[0300]

[13] M. A. Jameel, T. C.-J. Yang, G. J. Wilson, R. A. Evans, A. Gupta, S. J. Langford, Journal of Materials Chemistry A 2021, 9, 27170.

[0301]

[14] A. A. Said, S. M. Wagalgave, J. Xie, A. L. Puyad, W. Chen, Z. Wang, S. V. Bhosale, S. V. Bhosale, Q. Zhang, Journal of Solid State Chemistry 2019, 270, 51.

[0302]

[15] A. A. Said, J. Xie, Q. Zhang, Small 2019, 15, 1900854.

[0303]

[16] S. Valero, A. Cabrera-Espinoza, S. Collavini, J. Pascual, N. Marinova, I. Kosta, J. L. Delgado, European Journal of Organic Chemistry 2020, 2020, 5329.

[0304]

[17] S. Peng, J. Miao, I. Murtaza, L. Zhao, Z. Hu, M. Liu, T. Yang, Y. Liang, H. Meng, W. Huang, Journal of Materials Chemistry C 2017, 5, 5949.

[0305]

[18] L. Li, Y. Wu, E. Li, C. Shen, H. Zhang, X. Xu, G. Wu, M. Cai, W.-H. Zhu, Chemical Communications 2019, 55, 13239.

[0306]

[19] R. Azmi, E. Ugur, A. Seitkhan, F. Aljamaan, A. S. Subbiah, J. Liu, G. T. Harrison, M. I. Nugraha, M. K. Eswaran, M. Babics, Y. Chen, F. Xu, T. G. Allen, A. u. Rehman, C.-L. Wang, T. D. Anthopoulos, M. De Bastiani, E. Aydin, S. De Wolf, Science 2022, 376, 73.

[0307]

[20] X. Deng, F. Qi, F. Li, S. Wu, F. R. Lin, Z. Zhang, Z. Guan, Z. Yang, C.-S. Lee, A. K.-Y. Jen, Angewandte Chemie International Edition 2022, 61, e202203088.

[0308]

[21] R. Azmi, W. T. Hadmojo, S. Sinaga, C.-L. Lee, S. C. Yoon, I. H. Jung, S.-Y. Jang, Advanced Energy Materials 2018, 8, 1701683.

[0309]

[22] C. Bi, Q. Wang, Y. Shao, Y. Yuan, Z. Xiao, J. Huang, Nature Communications 2015, 6, 7747.

[0310]

[23] A. Farag et al., Adv. Energy Mater. 2023, 13, 2203982.

Claims

1. A compound of formula (I), (IV), or (V): Wherein X is selected from -L1-A1, H, NH2, C1-C 10 alkyl, C2-C 10 alkenyl, C2-C 10 alkynyl, C4-C 10 aryl, C4-C 20 alkylaryl, C4-C 20 alkenylaryl and C4-C 20 alkynylaryl, each of which is optionally substituted by C1-C 10 alkyl, C2-C 10 alkenyl, C2-C 10 alkynyl, C1-C 10 heteroalkyl, C4-C 10 aryl, C2-C 10 heteroalkenyl, C2-C 10 heteroalkynyl, C4-C 10 heteroaryl or substituted with one or more heteroatoms selected from N, S, and O; R1, R2, R3, and R4 are independently selected from H, CN, Cl, Br, F, CF3, NO2, C1-C 20 -alkyl, C 2-20 -perfluoroalkyl, C 5-20 -aryl, C 5-20 -heteroaryl; A, A1, and A2 are independently selected from phosphonic acid, monoalkyl ethers of phosphonic acid, phosphoric acid, monoalkyl ethers of phosphoric acid: Or the structure: R7 is a C1-C9 alkyl group; L and L1 are independently selected from C1-C9 alkylene, C4-C 20 arylene, C4-C 20 heteroarylene, C4-C 20 alkylarylene, C4-C 20 alkenylarylene, C4-C 20 heteroalkylarylene, C4-C 20 heteroalkenylarylene, wherein the heteroatom is selected from O, N, S, Se, Si, or from the following structures:

2. The compound according to claim 1, wherein the compound is a compound of formula (I).

3. The compound according to claim 1 or 2, wherein when each of R1, R2, R3, R4 is H, and each of A, A1 is phosphonic acid, then L, L1 are independently selected from C3-C9 alkylene, C4-C 20 arylene, C4-C 20 heteroarylene, C4-C 20 alkylarylene, C4-C 20 heteroalkylarylene, C4-C 20 heteroalkenylarylene, wherein the heteroatom is selected from O, N, S, Se, Si, or is selected from the following structures:

4. The compound according to any one of the preceding claims, wherein A, A1, and A2 are phosphonic acids.

5. The compound according to any one of the preceding claims, wherein L and L1 are the same.

6. The compound according to any one of the preceding claims, wherein X is -L1-A1.

7. The compound according to any one of claims 1 to 4, wherein X is selected from H, NH2, C1-C 10 alkyl, C2-C 10 alkenyl, C2-C 10 alkynyl, C4-C 10 aryl, C4-C 20 alkylaryl, C4-C 20 alkenylaryl and C4-C 20 alkynylaryl, each of which is optionally substituted by C1-C 10 alkyl, C2-C 10 alkenyl, C2-C 10 alkynyl, C1-C 10 heteroalkyl, C4-C 10 aryl, C2-C 10 heteroalkenyl, C2-C 10 heteroalkynyl, C4-C 10 heteroaryl or one or more heteroatoms selected from N, S, and O.

8. The compound according to claim 7, wherein X is selected from C4-C optionally substituted with C1-C 10 alkyl-substituted C4-C 20 alkylaryl.

9. A composition comprising one or more compounds according to any one of the preceding claims.

10. The composition according to claim 9, further comprising a filler molecule (FM), wherein the filler molecule is at least one molecule consisting of an anchoring group, an alkyl chain of N carbon atoms, where N is 1-18, and at least one functional group selected from methyl, halogen, amino, bromine, ammonium, and sulfuric acid functional groups.

11. An optoelectronic and / or photoelectrochemical device comprising an electron transport layer, wherein the electron transport layer comprises a compound according to any one of claims 1 to 8 or a composition according to claim 9 or 10.

12. The optoelectronic and / or photoelectrochemical device according to claim 11, wherein the device is selected from photovoltaic devices, organic photovoltaic devices, photovoltaic solid-state devices, organic solar cells, solid-state solar cells, perovskite solar cells, tandem solar cells, light-emitting electrochemical cells, and OLEDs.

13. The optoelectronic and / or photoelectrochemical device according to claim 12, wherein the device is a photovoltaic device.

14. The photovoltaic device according to claim 13, which comprises a conductive support layer covered with an electron transport layer, a sensitizer layer, a hole transport layer, and a counter electrode, wherein the electron transport layer comprises a compound according to any one of claims 1 to 8 or a composition according to claim 9 or 10.

15. The photovoltaic device according to claim 14, wherein the electron transport layer consists of a compound according to any one of claims 1 to 8 or a composition according to claim 9 or 10.

16. The photovoltaic device according to any one of claims 12 to 15, wherein the device is a tandem solar cell, preferably wherein the tandem solar cell comprises at least one perovskite solar cell.

17. The photovoltaic device according to any one of claims 14 to 16, wherein the sensitizer layer comprises an organic-inorganic perovskite.

18. The photovoltaic device according to claim 17, wherein the organic-inorganic perovskite is a perovskite-type structure of formula (II): AMX3 (II) Wherein: A is an alkali metal ion, preferably Li + , Na + , K + , Rb + , Cs + ; ammonium or amidinium ions in which one or more hydrogens are replaced by alkyl or acyl groups; M is a divalent metal cation selected from the group consisting of: Cu 2+ , Ni 2+ , Co 2+ , Fe 2+ , Mn 2+ , Cr 2+ , Pd 2+ , Cd 2+ , Ge 2+ , Sn 2+ , Pb 2+ , Eu 2+ , or Yb 2+ ; X is a monovalent anion independently selected from the group consisting of: Cl - , Br - , I - , NCS - , CN - , and NCO - .

19. The photovoltaic device according to claim 18, wherein the organic-inorganic perovskite is a mixed perovskite-type structure according to formula (III): A 1 1-y A 2 y PbX 1 3-z X 2 z(III) Wherein: A 1 and A 2 are independently selected from Li + 、Na + 、K + 、Rb + 、Cs + an organic monovalent cation of ammonium or amidinium ion; wherein one or more hydrogens of said ammonium or amidinium ion are substituted by alkyl or acyl or halogen; X 1 and X 2 are the same or different monovalent anions selected from Cl - , Br - , I - , NCS - , CN - , and NCO - ; y is in the range between 0.1 and 0.9; And z is in the range between 0.2 and 2.

20. The photovoltaic device according to any one of claims 14 to 19, wherein the conductive support layer comprises a conductive material selected from indium-doped tin oxide (ITO), indium zinc oxide (IZO), fluorine-doped tin oxide (FTO), metals, and / or other conductors.

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