Metal oxide-polymer composites for dense semiconductor thin films

Abstract

Provided are metal oxide nanocomposites, and compositions of forming metal oxide nanocomposites, for a solar cell. The metal oxide nanocomposites include an additive, such as a polymeric material, a carbon-based material, and / or a reactive monomer, in an amount from 0.01 wt.% to 49 wt.%, based on a total weight of the metal oxide nanocomposite. The metal oxide nanocomposites include a plurality of metal oxide nanoparticles, where at least a portion of the nanoparticles include one or more ligand-stabilized functionalizations and are homogenously dispersed in the nanocomposite. Further, the metal oxide nanocomposite is in the form of a thin film.

Description

Attorney Docket No.: 117442-1557010-000110WOMETAL OXIDE-POLYMER COMPOSITES FOR DENSE SEMICONDUCTOR THIN FILMSCROSS-REFERENCES TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent ApplicationNo. 63 / 790,954, filed April 18, 2025, which is incorporated by reference in its entirety for all purposes.FIELD OF THE INVENTION

[0002] The present disclosure relates to the integration of nanoparticle-based materials into devices. In particular, but not by way of limitation, the present invention relates to improved materials including nanoparticles that exhibit improved film quality, allowing the resulting nanoparticle containing materials to be incorporated into a large range of devices.BACKGROUND

[0003] Recent advances in nanoparticle synthesis and deposition techniques have allowed for the formation of a host of new applications containing nanoparticles. For example, PCT Pat. App. No. PCT / US2022 / 076697, filed 2022-09-20, discloses methods for preparing perovskite solar cells including functionalized nanoparticles.

[0004] Metal oxide nanomaterials have emerged as versatile functional materials due to their exceptional electrical, magnetic, mechanical, optical, and catalytic properties. Their unique physicochemical characteristics, driven by high surface-to-volume ratios and tunable morphologies, have enabled widespread use in gas sensors, fuel cells, batteries, ceramics, supercapacitors, chemical and biosensors, and more recently, optoelectronic devices such as solar cells.

[0005] These metal oxide nanomaterials can be synthesized in a wide range of morphologies, including spherical particles, nanorods, nanowires, nanotubes, and star-shaped structures, and the specific morphology significantly influences the functional performance. Among these morphologies, spherical nanoparticles are particularly common due to scalable synthesis routes. However, spherical nanoparticles also present challenges in forming compact, void free films for thin-film applications. In particular, solution phase deposition of nanoparticles exhibits various problems, such as incompatibility with certain solutions, low film density, and others.

[0006] In the specific case of perovskite solar cells (PSCs), these deficiencies underscore the need for a new class of nanocomposite materials that: 1) integrate with perovskite layers viaAttorney Docket No.: 117442-1557010-000110WObenign solvents and low-temperature processing; 2) exhibit improved film morphology and coverage without the need for sacrificial ligands; 3) maintain or enhance charge transport properties; and / or 4) remain adaptable across both electron and hole transport layers in a wide range of PSC device architectures. Thus, there is a need for improved compositions for metal oxide materials suitable for use with a variety of applications.SUMMARY OF THE INVENTION

[0007] The following presents a simplified summary relating to one or more aspects and / or embodiments disclosed herein. As such, the following summary should not be considered an extensive overview relating to all contemplated aspects and / or embodiments, nor should the following summary be regarded to identify key or critical elements relating to all contemplated aspects and / or embodiments or to delineate the scope associated with any particular aspect and / or embodiment. Accordingly, the following summary has the sole purpose to present certain concepts relating to one or more aspects and / or embodiments relating to the mechanisms disclosed herein in a simplified form to precede the detailed description presented below.

[0008] Embodiments of the present disclosure include a liquid composition for forming a charge transport layer. The charge transport layer may comprise: an additive, wherein the additive may comprise a polymeric material, a carbon-based material, and / or a reactive monomer, which may be present in an amount from 0.01 wt.% to 49 wt.%, based on a total weight of the composition; a plurality of metal oxide nanoparticles, wherein at least a portion of the nanoparticles may comprise one or more ligand-stabilized functionalizations; and a solvent; wherein the plurality of metal oxide nanoparticles may be homogenously dispersed in the composition. The additive may comprise a conducting or semiconducting material, an insulating polymer or binder, reactive monomers, or combinations thereof. The additive may comprise polymethyl methacrylate (PMMA), polyaniline, carbon 60 (C60), phenyl-C61 -butyric acid methyl ester (PCBM), graphene, poly(2,3-dihydrothieno-l,4-dioxin)-poly(styrenesulfonate) (PEDOT :PSS), poly(3 -hexylthiophene) (P3HT), polyethylenimine (PEI), polyethyleneimine ethoxylated (PEIE), polyvinylpyrrolidone (PVP), carbon nanotubes (CNTs), reduced graphene oxide (rGO), polyvinyl alcohol (PVA), polystyrene (PS), polyethylene glycol (PVG), polyacrylic acid (PAA), combinations thereof, or reactive monomers thereof. The plurality of metal oxide nanoparticles may comprise SnCE, NiOx, CuO, MoOx, or combinations thereof. The metal oxide nanoparticles may comprise a spherical shape.

[0009] Embodiments of the present disclosure include a method for producing a charge transport layer. The method may comprise: functionalizing hydrous metal oxide nanoparticles with a ligandAttorney Docket No.: 117442-1557010-000110WOto form ligand-stabilized metal oxide nanoparticles, combining the ligand-stabilized metal oxide nanoparticles with an additive, dispersing the combined functionalized metal oxide nanoparticles and the additive into a solvent to form a homogenous dispersion depositing a layer of the homogenous dispersion onto a surface, forming the charge transport layer. The method may further comprise removing some or all of the solvent to form a thin film, wherein the thin film, after removal of the solvent, may comprise a thickness of 60 nm or less. The layer of the homogenous dispersion may be treated with heat, UV, or environmental exposure to form the thin film. The layer of the homogenous dispersion may be treated at a temperature from 25°C to 165°C. The layer of the homogenous dispersion may treated for a minimum of 10 minutes. The layer of the homogeneous dispersion may be deposited with spin coating, blade coating, slot-die coating, gravure printing, inkjet printing, or combinations thereof.

[0010] Embodiments of the present disclosure include a metal oxide nanocomposite for a solar cell. The metal oxide nanocomposite for a solar cell may comprise: an additive, wherein the additive may comprise a polymeric material, a carbon-based material, and / or a reactive monomer, and may be present in an amount from 0.01 wt.% to 49 wt.%, based on a total weight of the nanocomposite; and a plurality of metal oxide nanoparticles, wherein at least a portion of the nanoparticles may comprise one or more ligand-stabilized functionalizations; and wherein the plurality of metal oxide nanoparticles may be homogenously dispersed in the nanocomposite; and wherein the nanocomposite may comprise a thin film. The nanocomposite may comprise a total thin film volume, and wherein less than 40% of the total thin film volume may comprise void space. The additive may comprise polymethyl methacrylate (PMMA), polyaniline, carbon 60 (C60), phenyl-C61 -butyric acid methyl ester (PCBM), graphene, poly(2,3-dihydrothieno-l,4-dioxin)-poly(styrenesulfonate) (PEDOT:PSS), poly(3 -hexyl thiophene) (P3HT), polyethylenimine (PEI), polyethyleneimine ethoxylated (PEIE), polyvinylpyrrolidone (PVP), carbon nanotubes (CNTs), reduced graphene oxide (rGO), polyvinyl alcohol (PVA), polystyrene (PS), polyethylene glycol (PVG), polyacrylic acid (PAA), combinations thereof, or reactive monomers thereof. The plurality of metal oxide nanoparticles may comprise SnCh, NiOx, CuO, MoOx, or combinations thereof. The solar cell may comprise the metal oxide nanocomposite of previous embodiments. The solar cell may comprise a perovskite solar cell, which may comprise: a glass layer; a hole transport layer that may be deposited on the glass layer; an interface layer that may be deposited on the hole transport layer; a perovskite layer that may be deposited on the interface layer; and the metal oxide nanocomposite layer that may be deposited on the perovskite layer. The solar cell may further comprise an electrode layer disposed over the nanocomposite layer, wherein the electrode layer may comprise silver (Ag) ITO, gold (Au), carbon, or copper (Cu). The metal oxideAttorney Docket No.: 117442-1557010-000110WOnanocomposite layer may comprise an electron transport layer. The solar cell may comprises a power conversion of greater than or about 15% per 0.1 cm2.

[0011] These and other features, and characteristics of the present technology, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. As used in the specification and in the claims, the singular form of ‘a,’ ‘an,’ and ‘the’ include plural referents unless the context clearly dictates otherwise.BRIEF DESCRIPTION OF DRAWINGS

[0012] FIG. 1 illustrates schematic illustration of a synthesis process for a polymeric mixture according to embodiments of the present technology.

[0013] FIG. 2 shows a schematic illustration of a blade coating process to form a SnO2 layer on perovskite within a perovskite solar cell configuration, in accordance with embodiments.

[0014] FIG. 3 shows a simplified illustration of an exemplary stack of layers within a perovskite solar cell system, in accordance with embodiments.

[0015] FIG. 4 shows an exemplary mechanism of increased layer density as a result of the incorporation of polymeric additives within the ETL, in accordance with embodiments.

[0016] FIG. 5 shows a graph and table summarizing exemplary J-V characteristics of SnCh devices with and without PMMA, in an embodiment.

[0017] FIG. 6 shows J-V curves of a perovskite solar cell including 0.05 wt% of PMMA in the SnCh composition, in accordance with an embodiment.

[0018] FIG. 7 shows J-V curves of a perovskite solar cell including 0.1 wt% of PMMA in the SnCh composition, in accordance with an embodiment.

[0019] FIG. 8 shows J-V curves of a perovskite solar cell including 5 wt% of PMMA in the SnCh composition, in accordance with an embodiment.

[0020] For simplicity and clarity of illustration, the drawing figures illustrate the general manner of construction, and descriptions and details of well-known features and techniques may beAttorney Docket No.: 117442-1557010-000110WOomitted to avoid unnecessarily obscuring the embodiments detailed herein. Additionally, elements in the drawing figures are not necessarily drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of the described embodiments. The same reference numerals in different figures denote the same elements.

[0021] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. In the following detailed description, references are made to the accompanying drawings that form a part hereof, and in which are shown by way of illustrations or specific examples. These aspects may be combined, other aspects may be utilized, and structural changes may be made without departing from the present disclosure. Example aspects may be practiced as methods, systems, or apparatuses. The following detailed description is therefore not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims and their equivalents.

[0022] As used herein, the terms “about” or “approximately” or “substantially” may be interpreted as being within a range that would be expected by one having ordinary skill in the art in light of the specification, such as, when used to modify a value, indicates that the value can be raised or lowered by 10% and remain within the disclosed aspect, such as 7.5%, such as 5%, such as 4%, such as 3%, such as 2%, such as 1 %, or any ranges or values therebetween.DETAILED DESCRIPTION OF THE INVENTION

[0023] In general, the present technology provides nanoparticle based materials that overcome one or more problems with prior solution phase nanoparticle compositions. In particular, the present disclosure discusses metal oxide and polymer composites that are well suited for the formation of dense semiconductor thin films.

[0024] It is notable that, while recent research efforts have explored the use of metal oxide nanomaterials and nanocomposites in optoelectronic and sensing applications, significant limitations remain in their application as charge transport layers in perovskite solar cells, especially with respect to solution-processable, scalable architectures. In particular, while an aqueous colloidal nanoparticle dispersion is commonly used for the deposition of nanomaterials, aqueous solvent systems limit the application to certain substrates, such as to n-i-p perovskite solar cell architectures, due to the incompatibility of perovskite structures with many common solvents.Attorney Docket No.: 117442-1557010-000110WO

[0025] For instance, some commercially available stabilized metal oxide nanoparticle compositions use ligand systems tailored for compatibility with alcohol-based solvents. However, these systems face performance limitations when deposited atop perovskite layers due to interfacial wetting and packing issues. Similarly, PCT Pat. App. No. PCT / US2006 / 045320 discloses the concept of functionalizing metal oxide nanoparticles to tune optical properties for display or coating applications. However, the described methods do not consider optimization of electrical performance or solvent compatibility with materials such as perovskites. There is also no discussion of the use of materials such as SnCh as a target material, nor does it address band alignment, interfacial energetics, or charge extraction efficiency in photovoltaic devices.

[0026] As another example, above-referenced PCT Pat. App. No. PCT / US2022 / 076697 discloses methods for enhancing electron transport layers using conductive cross-linking polymers in conjunction with functionalized metal oxide nanoparticles. However, the methods disclosed in above-referenced PCT Pat. App. No. PCT / US2022 / 076697 rely on functionalizing and removing ligands from metal oxide materials. The core strategy involves chemically modifying the surface of the nanoparticles with functionalizing agents that may be removed during processing. While this method can lead to improved thin film formation and interfacial contact, it introduces added complexity and is not always compatible with the moisture- or solvent-sensitive perovskite layers. Furthermore, the methods are limited to specific chemistries and deposition conditions, restricting its broader use across device architectures and materials systems. Moreover, the removal of the ligands is known to result in nanoparticle voids that reduce electron mobility. This results in the escape of I- ions from the perovskite layer, sub-optimal charge extraction from the perovskite layer (which can induce degradation), and back metal contact ingress forming shunting pathways in the module. The combination of these effects negatively impact performance metrics of the module, such as open-circuit voltage, short-circuit current, fill factor, and power conversion efficiency.

[0027] Additionally, the existing approaches related to nanocomposites do not form a compact thin film suitable for use with difficult applications such as perovskite solar cells. Further, many previous disclosures focus on optical, sensing, or structural properties without addressing charge transport or energy alignment for perovskites. Few incorporate or enable doping, and many omit key photovoltaic materials such as SnCh or NiOx. Many formulations require harsh solvents, functionalizing agents, or post-deposition processing steps that are incompatible with sensitive perovskite layers. Further, vacuum-based deposition or solvent systems that degrade perovskites remain common, limiting the relevance for scalable, solution-processed PSCs.Attomey Docket No.: 117442-1557010-000110WO

[0028] Furthermore, nanomaterials have been the subject of research for a variety of applications including photovoltaic materials. Due to their favorable electrical, magnetic, mechanical, optical, and catalytic properties, metal oxide-based nanomaterials are playing an important role in a wide range of applications, including gas sensors, fuel cells, advanced ceramics, chemical sensors, biosensors, batteries, solar cells, pyroelectric supercapacitors, catalysis, anticorrosion coatings, and others. Metal oxide nanomaterials may exhibit different morphologies, such as spherical, triangular, star, nanowire, nanotube, nanorod, and others, which enable high packing density. However, particularly in thin film applications, achieving homogeneous dispersion of the metal oxide nanoparticles and / or films with low void volumes are a challenge.

[0029] Altogether, nanocomposite formulations represent a promising path forward for a variety of applications, most work to date has focused on either non-electronic applications or narrow classes of additives, leaving an opportunity for more generalized formulations that balance solution-processability, interfacial compatibility, charge transport enhancement in both ETL and HTL contexts, and other electronic and optoelectronic devices.

[0030] Metal oxide nanomaterials have been used in the design of perovskite solar cells (PSCs), particularly as components of charge transport layers (CTLs), which include both electron transport layers (ETLs) and hole transport layers (HTLs). These layers facilitate the selective extraction and transport of charge carriers, namely electrons and holes, while blocking the opposite charge to prevent recombination. The material properties of CTLs are critical for device efficiency, stability, and manufacturability.

[0031] Metal oxides are widely adopted as ETLs due to their favorable characteristics: appropriate conduction band alignment with perovskite layers, high electron mobility, low optical absorption in the visible range, and chemical stability. Commonly used ETL materials include tin oxide (SnCE), titanium dioxide (TiCE), and zinc oxide (ZnO). Among these ETL materials, SnCE is often preferred for its compatibility with low-temperature processing and ability to deliver high power conversion efficiencies (PCEs), usually exceeding 25%. However, existing metal oxide nanomaterials exhibit issues such as interparticle voids, rough surface morphology, and limited control over interfacial energetics can negatively impact device reproducibility and performance.

[0032] Less widely explored, yet increasingly relevant, are metal oxides for HTL applications. Transition metal oxides such as nickel oxide (NiOx), molybdenum oxide (MoOx), and copperbased oxides have shown promise as hole transport layers due to their deep valence band positions, stability under illumination, and potential for high work function alignment with perovskite absorbers. These materials also offer advantages over conventional organic HTLs, such as 20,7,70-Attorney Docket No.: 117442-1557010-000110WOtetrakis[N,N-di(4-methoxyphenyl)amino]-9,90-spirobifluorene (Spiro-OMeTAD, CAS number 207739-72-8, available from OssilaLtd), or Poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA, CAS number 1333317-99-9, also available from OssilaLtd), which can be expensive, hygroscopic, and / or chemically unstable under operational conditions.

[0033] Despite their attractive properties, metal oxide materials face several challenges when used as charge transport layers in perovskite solar cells, such as the following issues:

[0034] 1) Thin film Uniformity and Morphological Control: Achieving uniform and compact thin films from nanoparticle dispersions can be difficult. Issues such as particle agglomeration, non-uniform packing, and adverse coating behaviors during solution-based deposition can lead to incomplete surface coverage, pinholes, or poor layer conformity, especially over rough or delicate perovskite layers. These defects can act as recombination sites and reduce device performance.

[0035] 2) Interfacial Compatibility with Perovskites: Metal oxide nanoparticle compositions are often stabilized in aqueous or alcohol-based solvents that are incompatible with halide perovskites, which are highly sensitive to moisture and polar solvents. Unless the metal oxide surface is functionalized or passivated, the material is typically limited to deposition beneath the perovskite absorber (e.g., in n-i-p architectures) or require vacuum deposition methods, during which no solvent contact occurs. These limitations restrict the design flexibility for scalable, fully solution-processed PSCs, particularly in inverted (p-i-n) structures.

[0036] 3) Electronic Property Control: While the conductivity and band alignment of metal oxides can be tuned through intentional doping, improper control of nanoparticle morphology, aggregation, or surface states can introduce resistive losses. Such non-idealities may hinder charge extraction or introduce energetic barriers at the interface.

[0037] 4) Surface Reactivity and Stability: Certain metal oxides may participate in redox reactions at the perovskite interface, especially under illumination or bias. These reactions can degrade the perovskite or form interfacial defect states that accelerate degradation of the PSCs. Addressing this reactivity through surface modification or passivation is often necessary to ensure long-term device stability.

[0038] Surprisingly, the present technology has found that utilizing an inorganic-organic nanocomposite that contains a metal oxide and one or more additives to functionalize the metal oxide nanoparticles for use in perovskite solar cells, improved coatings and thin films can be provided that are particularly well suited for use in solar cells. For instance, nanocomposites asAttorney Docket No.: 117442-1557010-000110WOdiscussed herein may increasing desirable properties such as, but not limited to, durability, stability, and power output.

[0039] It is recognized that, in prior publications involving the use of polymers within perovskite solar cells, the polymeric material functions as the hole transport layer (HTL) as the sole active material used for charge extraction on the relevant side of the device. In contrast, the present disclosure does not replace the ETL with a polymer. Instead, the present disclosure incorporates additives (polymeric or carbon-based) into a bulk metal oxide nanoparticle matrix to form a nanocomposite, thus improving device performance. More particularly, while the concept of using polymer-based charge transport materials, either as HTLs or ETLs, has been explored in prior publications, the present disclosure provides embodiments including CTLs with a composite nature. That is, rather than relying solely on the polymer for charge transport, the presently disclosed approach provides a path toward optimization of liquid metal oxide nanoparticle compositions by tuning their morphology and interface properties with small amounts of additives.

[0040] In other words, the specific composition, structure, and application of this metal oxide nanocomposite approach within perovskite solar cells provide heretofore unavailable and improved performance of the resulting device.

[0041] As recognized herein, polymer-metal oxide nanocomposites offer several distinct advantages for integration, particularly into PSC systems, if the above described deficiencies may be overcome. Polymers can act as matrix materials or binding agents that facilitate uniform thin film formation by reducing interparticle voids and mitigating aggregation. When well -dispersed, these polymers can enable smoother, more conformal coatings on top of perovskite layers, which characteristic may be especially important in inverted (p-i-n) architectures where the ETL is deposited last. Depending on their chemical structure, polymer additives may also modulate the surface energy of the formulation, improve adhesion to the underlying substrate, and enhance mechanical flexibility. A desirable surface energy for embodiments of the present disclosure may be from 35 mJ / m2to 60 mJ / m2, e.g, from 35 mJ / m2to 50 mJ / m2, from 50 mJ / m2to 60 mJ / m2, or any range of values therebetween. Further, the presence of metal oxide nanoparticles may improve thermal stability, roughness, glass transition temperature, optical tensile strength, and other properties of the resulting polymer nanocomposites.

[0042] To address the above-mentioned limitations, the present specification has explored composite formulations that blend metal oxide nanoparticles with functional additives, such as including polymers, carbon nanomaterials, and dopants, to improve nanocomposite thin film morphology, surface coverage, electrical conductivity, and processing compatibility. Such metalAttorney Docket No.: 117442-1557010-000110WOoxide nanocomposite systems offer a path to develop high-performing CTLs with tailored functionality for both n-i-p and p-i-n architectures. For example, researchers have explored hybrid strategies that incorporate functional additives, such as polymers and carbon-based nanomaterials, into metal oxide nanoparticle formulations. Surprisingly these nanocomposite systems improve thin film morphology, electronic functionality, and interfacial compatibility, while maintaining optical transparency and chemical stability.

[0043] Whereas organic metal oxide composite materials based on conductive cross-linking polymers have been used for a variety of applications, the use of nanocomposite materials such as disclosed herein in a manner compatible with difficult materials, such as perovskite, have not been heretofore contemplated. In particular, metal oxide-polymer composites suitable for use as the basis of an effective, electron transport layer within a perovskite solar cell are not currently available. The metal oxide nanocomposites disclosed herein are compatible with perovskites due to their solubility in perovskite-compatible solvents. While polymers are commonly compatible with perovskite-compatible solvents, the addition of metal oxides can lead to solvent incompatibility. The present disclosure overcomes these limitations with the use of functionalized metal oxide particles, as the functionalization thereof promotes compatibility with perovskitecompatible solvents. Further, while the present disclosure focuses on examples of polymer-metal oxide nanocomposites suitable for use with perovskite solar cell applications, the material may also be useful for other types of solar cells and other optoelectronic applications, such as light emitting diodes, gas sensors, infrared blockers, and others.

[0044] It is recognized herein that a crucial aspect in achieving a polymer-metal oxide nanocomposites with a nanophase-separated structure is the homogeneous dispersion of the metal oxide nanoparticles throughout the matrix. Specifically, minimizing the size and size distribution of the polymer-metal oxide composite domains in solution is essential, as domain size governs both the uniformity of nanoparticle dispersion within the film and the macroscopic film coverage. A homogeneous dispersion of the metal oxide nanoparticles throughout the polymer matrix is therefore essential for improved perovskite solar cell performance.

[0045] Furthermore, it would be desirable to ensure solvent compatibility of the polymer-metal oxide nanocomposites with a variety of different metal oxides and applications, such as perovskite. Additionally, it would be desirable to modify the electronic properties of the resulting polymer-metal oxide nanocomposite, for example, by appropriate doping of the metal oxide nanoparticles, while maintaining transparency over a desired wavelength spectrum range for the resulting perovskite and / or tandem architectures. The desired wavelength spectrum range for the perovskiteAttorney Docket No.: 117442-1557010-000110WOmay range from 300 nm to 750 nm, e.g., from 300 nm to 650 nm, from 300 nm to 550 nm, from 300 nm to 450 nm, from 300 nm to 350 nm, from 400 nm to 750 nm, from 400 nm to 650 nm, from 400 nm to 550 nm, from 400 nm to 450 nm, from 500 nm to 750 nm, from 500 nm to 650 nm, from 500 nm to 550 nm, from 600 nm to 750 nm, from 600 nm to 650 nm, and from 700 nm to 750 nm. The desired wavelength spectrum range for the resulting tandem architecture may be from 300 nm to 1200 nm, e.g., from 300 nm to 1000 nm, from 300 nm to 800 nm, from 300 nm to 600 nm, from 300 nm to 400 nm, from 400 nm to 1200 nm, from 400 nm to 1000 nm, from 400 nm to 800 nm, from 400 nm to 600 nm, from 600 nm to 1200 nm, from 600 nm to 1000 nm, from 600 nm to 800 nm, from 800 nm to 1200 nm, from 800 nm to 1000 nm, and from 1000 nm to 1200 nm. Still further, it is recognized herein that a combination of conductive polymers with metal oxide nanoparticles enables further tailoring of the electronic properties of the resulting metal oxide nanocomposite thin film, particularly for optoelectronic and sensor applications.

[0046] Thus, the present disclosure provides polymer-, carbon-, and reactive monomer-enhanced metal oxide nanocomposites that are: 1) compatible with perovskite layers, enabling direct deposition in inverted (p-i-n) and / or tandem architectures; 2) processable in non-aqueous solvents, preserving perovskite integrity and expanding formulation flexibility; 3) capable of improved thin film morphology, through the use of additives that reduce interparticle voids, suppress aggregation, and enhance surface coverage; 4) electrically and optically tunable, through the integration of functional additives and dopants that modulate conductivity, band alignment, and transparency; and / or 5) applicable to both ETLs and HTLs, allowing the same formulation principles to be applied to a variety of metal oxides, such as SnCE, NiOx, CuO, and MoOx. Unlike existing methods that rely on sacrificial ligands or narrowly scoped functionalization strategies, embodiments of the present disclosure leverage stable, non-reactive additives, such as PMMA, C60, graphene, PEDOT:PSS, polyaniline, and others, to improve the physical structure and electrical performance of CTLs, which may be either ETLs and HTLs, without introducing degradation pathways or requiring high-temperature processing.

[0047] Beyond polymers, conductive and semi conductive carbon-based additives such as graphene, C60, PEDOT:PSS, and polyaniline have demonstrated utility in nanocomposite formulations. As the present disclosure illustrates, these additives can introduce additional charge transport pathways, facilitate electronic coupling at interfaces, or serve as structural frameworks to reduce pinholes and improve surface coverage. Further, the present technology has surprisingly found that non-conductive polymers such as polymethyl methacrylate (PMMA), when integrated into optimized metal oxide dispersions, can improve the dry metal oxide nanocomposite thin film morphology in ways that indirectly enhance charge transport and reduce recombination losses.Attorney Docket No.: 117442-1557010-000110WO

[0048] Further, in embodiments, the metal oxide nanocomposite systems, which may include electron transport layers (ETLs), described herein may further include reactive monomers that are capable of undergoing in situ polymerization or crosslinking upon exposure to specific stimuli. Monomers may be used instead of polymers, or in addition to polymers. These monomers, for example, may be thermally activated (e.g., epoxies), photo-activated (e.g., acrylates), or initiated under anaerobic or moisture-sensitive environments (e.g., cyanoacrylates).

[0049] It is recognized herein that reactive monomers have previously been utilized in the context of perovskite solar cells, such as typically within the perovskite absorber layer itself or as part of a polymeric encapsulation strategy. In contrast, embodiments of the present disclosure use reactive monomers as functional additives within the charge transport layer, such as within a metal oxide-based ETL. In embodiments, unlike approaches that rely on the polymerization of monomers as part of the bulk perovskite film, the inclusion of reactive monomers in the SnCE-based nanocomposite formulation enables tuning of interfacial, morphological, and stability characteristics directly at the CTL interface.

[0050] In certain embodiments, the reactive monomer may be co-deposited with the liquid metal oxide nanoparticle composition and subsequently polymerized after deposition using heat, light, or environmental exposure. Depending on the monomer, polymerization may take place at a temperature as low as 25°C. Typically, polymerization may take place at temperatures ranging from 25°C to 150°C, e.g., from 25°C to 125°C, from 25°C to 100°C, from 25°C to 75°C, from 25°C to 50°C, from 50°C to 150°C, from 50°C to 125°C, from 50°C to 100°C, from 50°C to 75°C, from 75°C to 150°C, from 75°C to 125°C, from 75°C to 100°C, from 100°C to 150°C, from 100°C to 125°C, and from 125°C to 150°C. At lower temperatures, UV or catalytic activation may be required to initiate polymerization. In certain embodiments, the metal oxide may provide catalytic activation, or an additional catalyst may be included. Polymerization time may vary greatly depending on the composition and / or reactive monomer, ranging from several minutes to several days. In certain embodiments, the polymerization may be complete in 5 hours or less. The resulting material is a hybrid metal oxide nanocomposite, wherein the metal oxide network is interpenetrated with an in situ-formed polymer matrix. This structure offers several potential advantages, including enhanced thin film adhesion, suppression of interfacial defects, and improved environmental and mechanical stability of the ETL. In this way, in contrast to previously published uses of in situ polymerizable systems, the approach described herein enables tailoring of the properties of CTLs in perovskite solar cells through post-deposition chemical structuring, rather than relying solely on compositional doping or blending.Attorney Docket No.: 117442-1557010-000110WO

[0051] Unlike existing methods that rely on sacrificial ligands or narrowly scoped functionalization strategies, embodiments of the present disclosure leverage stable, non-reactive additives, such as PMMA, C60, graphene, PEDOT:PSS, polyaniline, and others, to improve the physical structure and electrical performance of CTLs without introducing degradation pathways or requiring high-temperature processing.

[0052] Embodiments of the present disclosure incorporate conductive, cross-linking polymers, with polymeric, carbon-based, and / or reactive monomer additives introduced directly into the formulation of ligand-stabilized structure nanoparticles. In some embodiments, the ligand may comprise a carboxylic acid base. Rather than removing the additives, the additives of the present disclosure are made to remain in the liquid metal oxide nanoparticle composition and the formed nanocomposite thin film, thus reducing nanoparticle voids and enhancing device performance by improving charge transport layer morphology and uniformity. In PSC applications, this approach provides high performance CTLs, supporting scalable manufacturing, improved device stability, and higher efficiency across multiple perovskite architectures.

[0053] In embodiments, the metal oxide nanocomposite thin film comprises a total thin film volume, wherein a portion of the thin film volume may comprise nanoparticle voids. In some embodiments, less than 40% of the total thin film volume may comprise void space.

[0054] In embodiments, the additive is one or more conductive polymers or organic semiconductors, such as a polymer, a carbon material, or a reactive monomer with a loading percentage for the additive being less than 49 wt% based on a total weight of the solids in the liquid metal oxide nanoparticle composition, e.g., from 0.01 wt% to 49 wt%, from 0.01 wt% to 40 wt%, from 0.01 wt% to 30 wt%, from 0.01 wt% to 20 wt%, from 0.01 wt% to 10 wt%, from 0.01 wt% to 5 wt%, from 0.01 wt% to 2 wt%, from 0.01 wt% to 1 wt%, from 0.01 wt% to 0.5 wt%, from 0.01 wt% to 0.1 wt%, or any ranges or values therebetween. In embodiments, the additive is PMMA and the loading percentage is in a range between 0.01 and 5 wt%, e.g., from 0.01 wt% to 4 wt%, from 0.01 wt% to 3 wt%, from 0.01 wt% to 2 wt%, from 0.01 wt% to 1 wt%, from 0.01 wt% to 1 wt%, from 0.01 wt% to 0.5 wt%, from 0.01 wt% to 0.1 wt% based on a total weight of solids in the liquid metal oxide nanoparticle composition, or any ranges or values therebetween.

[0055] In embodiments, the metal oxide nanoparticles may comprise 55 wt.% or less based on a total weight of the solids in the liquid metal oxide nanoparticle composition, e.g., from 1 wt.% to 55 wt.%, from 5 wt.% to 50 wt.%, from 10 wt.% to 45 wt.%, from 15 wt.% to 45 wt.%, from 20 wt.% to 45 wt.%, from 25 wt.% to 45 wt.%, from 30 wt.% to 45 wt.% from 35 wt.% to 45 wt.%, from 40 wt.% to 45 wt.%, from 41 wt.% to 45 wt.%, from 42 wt.% to 45 wt.%, from 43 wt.% toAttorney Docket No.: 117442-1557010-000110WO45 wt.%, from 44 wt.% to 45 wt.%, or any ranges or values therebetween. In some aspects, the metal oxide nanoparticles comprise from 40 wt.% to 45 wt.% based on a total weight of the solids in the liquid metal oxide nanoparticle composition.

[0056] In embodiments, the stabilizing ligand may comprise 45 wt.% or more based on a total weight of the solids in the liquid metal oxide nanoparticle composition, e.g., from 45 wt.% to 99 wt.%, from 50 wt.% to 90 wt.%, from 55 wt.% to 80 wt.%, from 55 wt.% to 70 wt.%, from 55 wt.% to 60 wt.%, from 55 wt.% to 58 wt.%, from 55 wt.% to 56 wt.%, or any ranges or values therebetween. In some aspects, the stabilizing ligand may comprise 55 wt.% to 60 wt.% more based on a total weight of the solids in the liquid metal oxide nanoparticle composition.

[0057] It is understood that the above-disclosed wt.% of the metal oxide nanoparticles, the additive, and the stabilizing ligand in the liquid metal oxide nanoparticle composition are exemplary, and they may be diluted or concentrated based on a variety of factors such as consumer desire and / or need. For instance, in embodiments, the above discussed weight percentages may be present in the liquid dispersion. Thus, in embodiments, the liquid dispersion may be diluted from 1 to 500 times prior to application to a substrate, such as from 5 to 250 times, from 10 to 100 times, from 15 to 90 times, from 20 to 80 times, from 25 to 75 times, from 30 to 70 times, from 35 to 65 times, from 40 to 60 times, or any ranges or values therebetween.

[0058] In embodiments, the additive may be a conductive polymer and / or an organic semiconductor. For example, the following materials may be suitable for use as an additive, in accordance with embodiments:

[0059] 1) Conducting / Semiconducting additives such as:

[0060] a) Carbon 60 (C60): Provides high electron mobility, passivate defects;

[0061] b) Phenyl-C61 -butyric acid methyl ester (PCBM): Similar advantages as C60;

[0062] c) Graphene;

[0063] d) Poly(2,3-dihydrothieno-l,4-dioxin)-poly(styrenesulfonate) (PEDOT:PSS):Improves ETL conductivity when acid treated or doped;

[0064] e) Poly(3 -hexylthiophene) (P3HT): Often used as HTL, blends with SnO2 have been demonstrated to enhance charge separation and morphology control;

[0065] f) Polyethylenimine (PEI): Improves interference dipoles on SnO2 and Indium- Tim-Oxide and provides enhanced electron extraction;Attorney Docket No.: 117442-1557010-000110WO

[0066] g) Polyethyleneimine ethoxylated (PEIE): Provides similar advantages to PEI;

[0067] h) Polyvinylpyrrolidone (PVP): Functions as a dispersant or stabilizer;

[0068] i) Carbon nanotubes (CNTs): Provides excellent electron mobility; and

[0069] j) Reduced graphene oxide (rGO): Provides good dispersibility with some conductivity (tunable conductivity); or

[0070] 2) Insulating Polymers / Binders, such as:

[0071] a) Polymethyl methacrylate (PMMA): Excellent for densifying thin films;

[0072] b) Polyvinyl alcohol (PVA): Enables control of film porosity;

[0073] c) Polystyrene (PS): Functions as a void-filling or morphology-modifying agent;

[0074] d) Polyethylene glycol (PVG): Enables control of thin film porosity; and

[0075] e) Polyacrylic acid (PAA): Improves surface modification and binding.

[0076] 3) Reactive monomers such as:

[0077] a) Acrylates: polymerize upon exposure to UV or visible light

[0078] 1) 2-Hydroxyethyl acrylate (HEA): Water-compatible, good adhesion promoter, forms hydrophilic networks.

[0079] 2) Methyl methacrylate (MMA): forms rigid transparent thin films.

[0080] 3) Ethoxylated trimethylolpropane triacrylate (ETPTA): A crosslinking monomer, commonly used in optical coatings and liquid metal oxide nanoparticle compositions.

[0081] 4) Polyethylene glycol diacrylate (PEGDA): Hydrophilic, biocompatible; useful for tailoring mechanical and permeability properties.

[0082] b) Epoxies: polymerize upon exposure to heat

[0083] 1) Bisphenol A diglycidyl ether (BADGE / DGEBA): forms rigid, high-strength networks.

[0084] 2) Cycloaliphatic epoxides (e.g., 3, 4-epoxycy cl ohexylmethyl-3', 'epoxycyclohexane carboxylate): Lower viscosity, UV-stable, used in electronics.

[0085] 3) Glycidyl methacrylate (GMA): A bifunctional monomer with both epoxy and acrylate groups — can be crosslinked via either heat or UV.Attorney Docket No.: 117442-1557010-000110WO

[0086] c) Cyanoacrylates: polymerize under anaerobic or moisture-controlled conditions.

[0087] 1) Ethyl cyanoacrylate: fast-curing in moist environments.

[0088] 2) Butyl cyanoacrylate: More flexible and less brittle; used in medical and flexible electronics applications.

[0089] 3) Octyl cyanoacrylate: Higher hydrophobicity, improved water resistance and flexibility.

[0090] Thus, in embodiments, the additives may include at least one of polymethyl methacrylate (PMMA), polyaniline, carbon 60 (C60), phenyl-C61 -butyric acid methyl ester (PCBM), graphene, poly(2,3-dihydrothieno-l,4-dioxin)-poly(styrenesulfonate) (PEDOT :PSS), poly(3 -hexylthiophene) (P3HT), polyethylenimine (PEI), polyethyleneimine ethoxylated (PEIE), polyvinylpyrrolidone (PVP), carbon nanotubes (CNTs), reduced graphene oxide (rGO), polyvinyl alcohol (PVA), polystyrene (PS), polyethylene glycol (PVG), and polyacrylic acid (PAA). As discussed above, in embodiments, the liquid metal oxide nanoparticle composition may form a metal oxide nanocomposite thin film upon deposition with a reduced volume of voids between nanoparticles and remains substantially unchanged during thermal processing. The resulting metal oxide nanocomposite thin film, when used in a perovskite solar cell, may provide improved power conversion efficiency relative to a thin film formed without one or more of the discussed additives. In some embodiments, the power conversion efficiency of a solar cell utilizing the resulting thin film may be greater than or about 15% per 0.1 cm2.

[0091] The result is a class of metal oxide nanocomposite thin film that exhibit significant performance improvements when used in difficult systems, such as perovskite solar cells. In embodiments, the inclusion of the additives, as described herein, provides an improvement of -0.020V in open circuit voltage (Voc), ~1 mA / cm2in short circuit current (Jsc), -4% in fill factor, and / or -2% in power conversion efficiency (PCE). For example, incorporation of PMMA into an ligand-stabilized metal oxide nanoparticle dispersion enabled the formation of a compact, uniform electron transport layer with a 2% absolute increase in power conversion efficiency over control samples. Importantly, this result was achieved without damage to the underlying perovskite layer and without sacrificing optical transparency.

[0092] Optical transparency, for the purposes of this disclosure, can be quantified by the transmittance (how much light passes through a material) of the metal oxide nanocomposite thin film. In some embodiments, the transmittance of the nanocomposite may be at least 80%, e.g., from 80% to 100%, from 80% to 95%, from 80% to 90%, from 80% to 85%, from 85% to 100%,Attorney Docket No.: 117442-1557010-000110WOfrom 85% to 95%, from 85% to 90%, from 90% to 100%, from 90% to 95%, and from 95% to 100%. In certain aspects, the transmittance through the desired wavelength spectrum range of perovskites as discussed above is greater than 95%.

[0093] Using the approaches described herein, the integration of metal oxide nanoparticles with polymers to form metal oxide nanocomposites offers an effective route to tailor material performance. Embodiments of the method disclosed herein enable homogeneous dispersion of nanoparticles throughout the polymer matrix, thus decreasing agglomeration while increasing interfacial interactions. For the purposes of this disclosure, the homogeneity of dispersion of the nanoparticles can be quantified by transmittance, as discussed above, and / or the average particle size. In some embodiments, the particle size of the metal oxide nanoparticle composite may be from 3 nm to 25 nm, or such as from 4 nm to 20 nm, or such as from 5 nm to 15 nm, or such as from 7 nm to 12 nm or any ranges or values therebetween. The resulting nanocomposites exhibit improved mechanical properties, thermal stability, optical clarity, and structural integrity. These tunable and enhanced properties enable the resulting metal oxide nanocomposite to be useful across a variety of advanced applications, including biomedical devices, protective coatings, structural materials, and optoelectronic devices.

[0094] FIG. 1 shows an exemplary synthesis process to produce a liquid metal oxide nanoparticle composition in accordance with the present technology. As shown in FIG. 1, the process begins with the synthesis 1001 of hydrous metal oxide nanoparticles, which in some embodiments may be SnCh nanoparticles. In some embodiments, the synthesis can include reacting a metal salt to form hydrous-metal oxide nanoparticles. This synthesis of the metal oxide from the metal salt may be accomplished by any suitable methods, including, precipitation and calcination, thermal decomposition, mechanochemical synthesis, or combinations thereof.

[0095] While FIG. 1 discussed herein refer to SnC>2,as an exemplary metal oxide, it should be clear that other metal oxide nanoparticles for use in the compositions herein include a metal oxide, a doped metal oxide, or a combination thereof, such as one or more of doped or undoped TiCh, SnCh, NiOx, CuO, ZnO, Z SC , WO3, I Ch, SrTiCh, Nb2Os, BaSnCh, Y:SnC>2, Cu:NiOx, or combinations thereof.

[0096] Once the metal oxide nanoparticles are formed and cleaned, the next step of the synthesis process is the functionalization 1002 of the hydrous metal oxide. In some embodiments, the hydrous metal oxide may be functionalized with a stabilizing ligand. The stabilizing ligand may comprise a carboxylic acid base or phosphonic acid base, which, in embodiments may have a general structure R — CO — OH, where R can be C1-C27 , or such as a C1-C20 , or such as C1-C15 , orAttorney Docket No.: 117442-1557010-000110WOsuch as C1-C10 , or such as C1-C4 , alky or salts thereof. In embodiments, the functionalization may include acetate, propionate, or combinations thereof.

[0097] Additional functionalizing compounds may comprise one or more of Rla-CO-OH or salts thereof, where Ria is substituted or unsubstituted alkyl; R2a-O-CS2'M+2a where R2a is substituted or unsubstituted alkyl, and M+2a is a cation; either of the following chemical structures:Where X3 is an anion; Rja, Rae, Rsd, and Rae is the same or different and is H, substituted or unsubstituted alkyl, or substituted or unsubstituted aryl; Rjb is H, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted Lewis base, quaternary nitrogen salts, carboxylates, xanthates, alkoxides, or thiolates; either of the following chemical structures:where X4 is an anion; R4a, R4c, R4d, R4e, Rrf, and R4gis the same or different and is H, substituted or unsubstituted alkyl, or substituted or unsubstituted aryl; R4b is H, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted Lewis base, quaternary nitrogen salts, carboxylates, xanthates, alkoxides, or thiolates; the following chemical structure:where Rsa, Rsb, and Rsc is the same or different and is H, substituted or unsubstituted alkyl, or substituted or unsubstituted aryl; the following chemical structure: where Reb, Rec, and Red is the same or different and is H, substituted or unsubstituted alkyl, or substituted or unsubstituted aryl; Rea is H, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, where the ReaAttorney Docket No.: 117442-1557010-0001 IOWOsubstituted alkyl is optionally substituted with one or more substituted or unsubstituted Lewis bases, quaternary nitrogen salts, carboxylates, xanthates, alkoxides, or thiolates, where the Rea substituted aryl is optionally substituted with one or more substituted or unsubstituted Lewis bases, quaternary nitrogen salts, carboxylates, xanthates, alkoxides, or thiolates; orR7a-NH-CS2'M+7a where R?a is a substituted or unsubstituted alkyl and M+2a is a cation. In certain embodiments, Ria is a substituted or unsubstituted Ci-Cs alkyl, methyl, ethyl, propyl, or butyl; and / or such as wherein R2a is a substituted or unsubstituted alkyl C1-C36 alkyl, methyl, ethyl, propyl, butyl, dodecyl, or octadecyl; M+2a is Na+, K+, or Li+; or a combination thereof; and / or such as wherein X3 is Cl’, Br’, L, BF4’, PFe’, or CFsSCh’; R3a, Rae, Rad, and R3e is the same or different and is H, substituted or unsubstituted Ci-Cs alkyl, or substituted or unsubstituted phenyl; Rab is H, substituted or unsubstituted Ci-Cs alkyl, substituted or unsubstituted phenyl, -C(O)H, -C(O)OH, -C(0)NHR3f, -CH2OR.31, -CH2NHR3f, quaternary nitrogen salts, carboxylates, xanthates, alkoxides, or thiolates, R.31 is H, substituted or unsubstituted Ci-Cs alkyl; or a combination thereof; and / or such as wherein X4 is CF, Br, I’, BF4’, PFe’, or CFsSCh’; R4a, R4c, R4d, R4e, R4f, and R4gis the same or different and is H, substituted or unsubstituted Ci-Cs alkyl, or substituted or unsubstituted phenyl; R4b is H, substituted or unsubstituted Ci-Cs alkyl, substituted or unsubstituted phenyl, -C(O)H, -C(O)OH, -C(0)NHR4h, -CH2OR.411, -CH2NHR4h, quaternary nitrogen salts, carboxylates, xanthates, alkoxides, or thiolates, R4h is H, substituted or unsubstituted Ci-Cs alkyl; or a combination thereof; and / or such as wherein Rsa, Rsb, and Rsc is the same or different and is H, substituted or unsubstituted Ci-Cs alkyl, or substituted or unsubstituted phenyl; and / or such as wherein Reb, Rec, and Red is the same or different and is H, substituted or unsubstituted Ci-Cs alkyl, or substituted or unsubstituted phenyl; Rea is H, substituted or unsubstituted Ci-Cs alkyl, substituted or unsubstituted phenyl, where the Rea substituted alkyl is optionally substituted with one or more -C(O)H, -C(O)OH, -C(O)NHRee, -CFLORee, -CH2NHRee, quaternary nitrogen salts, carboxylates, xanthates, alkoxides, or thiolates, where the Rea substituted aryl is optionally substituted with one or more -C(O)H, -C(O)OH, -C(O)NHRee, -CFLORee, -CH2NHRee, quaternary nitrogen salts, carboxylates, xanthates, alkoxides, or thiolates, Reeis H, substituted or unsubstituted Ci-Cs alkyl; or a combination thereof; and / or such as wherein R?a is a substituted or unsubstituted alkyl C1-C36 alkyl, methyl, ethyl, propyl, butyl, dodecyl, or octadecyl; M+7a is Na+, K+, or Li+; or a combination thereof; optionally wherein the chemical formula may be:Atorney Docket No.: 117442-1557010-000110WOand / or optionally wherein formula (V) is selected from triarylamines (TAA), substituted TAA, triphenylamine, substituted triphenylamines, triethylamine and substituted triethylamines.

[0098] The functionalization step may be accomplished by any suitable methods, which may include, but are not limited to, combining the hydrous metal oxide with the stabilizing ligand (for example, a carboxylic acid based ligand), heating the combination, and conducting a ligand exchange.

[0099] After the metal oxide nanoparticles are functionalized, the next step in the synthesis process is combining the functionalized metal oxide nanoparticles with an additive 1003. The combination may be accomplished by any suitable methods. The additive may be any of the additives listed above. In some embodiments, heat is introduced to the metal oxide nanoparticles and the additive to facilitate the combination.

[0100] The final step of the synthesis process may comprise dispersing 1004 the combined functionalized metal oxide nanoparticles and the additive into a solvent to form a homogenous dispersion, which may also be referred to as a liquid metal oxide nanoparticle composition. In some embodiments, the solvent may be a nonaqueous solvent. Examples of a nonaqueous solvent may include but is not limited to alcohols such as isopropanol, butanol, ethanol, or combinations thereof. While the metal illustrated in FIG. 1 shows SnCh, it should be clear that the process can be used with other metal oxide nanoparticles discussed herein. The homogeneous dispersion / liquid metal oxide nanoparticle composition may then be used for forming a metal-oxide nanocomposite thin film.

[0101] FIG. 2 shows a schematic illustration of a blade coating process to form a for forming a metal-oxide nanocomposite thin film, or in particular, a SnCh nanocomposite layer, as described above, on a perovskite layer within a perovskite solar cell configuration, in accordance with certain embodiments. For example, a perovskite solar cell may include a glass layer, for example an indium tin oxide (ITO)-coated glass 102 with a poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA) layer 104 deposited thereon as a holetransport layer (HTL). The HTL may alternatively comprise MeO-2PACz (SAM), NiOx, PEDOT:PSS, MoO3, V2O5, Spiro-OMeTAD. A poly [(9,9-Attorney Docket No.: 117442-1557010-000110WObis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene)-alt-2,7-(9,9- dioctylfluorene)] (PFN) layer 106 may be deposited on the HTL as an interface layer to improve extraction of the converted electrons from a perovskite layer 108 deposited thereon. Following deposition of the SnCh polymer composition (see FIG. 1), such as by blade coating, as an example, the SnCh nanoparticle thin film layer 110 is formed after appropriate processing steps, such as by application of heat, UV, environmental exposure, or other forms of energy to remove either some or all of the solvent. The processing steps may comprise drying the thin film layer for 5 minutes at 100°C to 120°C and then 20 minutes at 150°C. However, it should be clear that other drying times and temperatures are contemplated herein based upon the coating composition and coating thickness.

[0102] In embodiments, the metal oxide nanocomposite thin film may be produced using at least one of spin coating, blade coating, slot-die coating, gravure printing, and inkjet printing. In embodiments where printing is utilized, the liquid composition may be referred to as an “ink”.

[0103] In embodiments, the metal oxide nanocomposite thin film thickness after it has been cast but before either some or all of the solvent has been removed may be from 1000 nm to 3000 nm, e.g., from 1000 nm to 2750 nm, from 1000 nm to 2500 nm, from 1000 nm to 2250 nm, from 1000 nm to 2000 nm, from 1000 nm to 1750 nm, from 1000 nm to 1500 nm, from 1000 nm to 1250 nm, from 1250 nm to 3000 nm, from 1250 nm to 2750 nm, from 1250 nm to 2500 nm, from 1250 nm to 2250 nm, from 1250 nm to 2000 nm, from 1250 nm to 1750 nm, from 1250 nm to 1500 nm, from 1500 nm to 3000 nm, from 1500 nm to 2750 nm, from 1500 nm to 2500 nm, from 1500 nm to 2250 nm, from 1500 nm to 2000 nm, from 1500 nm to 1750 nm, from 1750 nm to 3000 nm, from 1750 nm to 2750 nm, from 1750 nm to 2500 nm, from 1750 nm to 2250 nm, from 1750 nm to 2000 nm, from 2000 nm to 3000 nm, from 2000 nm to 2750 nm, from 2000 nm to 2500 nm, from 2000 nm to 2250 nm, from 2250 nm to 3000 nm, from 2250 nm to 2750 nm, from 2250 nm to 2500 nm, from 2500 nm to 3000 nm, from 2500 nm to 2750 nm, from 2750 nm to 3000 nm, or any ranges or values therebetween. In certain embodiments, the metal oxide nanoparticle thin film thickness after either some or all of the solvent is removed may be from 20 nm to 60 nm thick, e.g., from 30 nm to 55 nm, from 30 nm to 50 nm, from 30 nm to 45 nm, from 35 nm to 50 nm, from 35 nm to 45 nm, from 35 nm to 40 nm, from 40 nm to 50 nm, from 40 nm to 45 nm, from 45 nm to 50 nm, or any ranges or values therebetween.

[0104] As shown in FIG. 3, a perovskite solar cell may further contain a metal layer 112 overlying the metal oxide nanocomposite thin film layer 110, shown as a silver (Ag) layer, as an electrode layer. The electrode layer may also comprise other common electrode materials, such as ITO, gold (Au), carbon, copper (Cu), or combinations thereof.Attorney Docket No.: 117442-1557010-000110WO

[0105] FIG. 4 illustrates an exemplary mechanism of increased layer density obtained through the incorporation of polymeric additives 150 within the liquid metal oxide nanoparticle composition 140, in accordance with embodiments. By integrating polymeric additives into the perovskite-compatible, liquid metal oxide nanoparticle composition used in forming the CTL, the polymeric additives 150 dispersed in the liquid composition fills in between the metal-oxide particles 140 to increase the layer density, thus improving the electrical properties of the resulting CTL, which in certain embodiments, may be an ELT as shown in Table 1.Table 1: Exemplary J-V characteristics of SnCh devices with and without PMMAFunctionalized SnO2+ PMMA Functionalized SnO2ControlAverage J-V Average J-VJsc 24.572 0.8368 Jsc 23.576 0.5507Foe 1.0976 0.0102 Foe 1.0779 0.0263FF 64.014 2.5829 FF 60.76 3.2845PCE 17.271 1.0349 PCE 15.437 0.9279

[0106] FIG. 5 shows a graph and a table, summarizing exemplary current density-voltage (J-V) characteristics of SnCh devices (e.g., as illustrated in FIG. 3) with and without inclusion of PMMA as a polymeric additive, in accordance with an embodiment. As may be seen in FIG. 5, the inclusion of the polymeric additive improves the overall current density performance of the analyzed device.

[0107] FIGS. 6 - 8 illustrate the J-V curves for a perovskite solar cell including various concentration values of PMMA added to the liquid metal oxide nanoparticle composite used in the formation of the ETL. This experiment was performed to identify the optimal PMMA loading for a given liquid metal oxide nanoparticle composite, in accordance with an embodiment.

[0108] In particular, FIG. 6 shows J-V curves of a perovskite solar cell including 0.05 wt% of PMMA in the SnCh liquid composition, in accordance with an embodiment. The graph shows the J-V curves obtained from measurement of multiple devices, including a layered structure illustrated at the top right of FIG. 6. Table 2 summarizes the average and standard deviation of the measured Jsc, Voc, fill factor (FF), and power conversion efficiency (PCE) performance of the measured devices.Table 2: 0.05 wt.% PMMA Perovskite performance measurementsJsc(mA / cm2) Voc(V) FF(%) PCE(%)Average -22.12 1.14 61.32 15.8SD 0.75 0.03 4.32 0.851.58Attorney Docket No.: 117442-1557010-000110WO

[0109] FIG. 7 shows J-V curves of a perovskite solar cell including 0.1 wt% of PMMA in the SnCh liquid composition, in accordance with an embodiment. Again, the graph shows the J-V curves obtained from measurement of multiple devices, including a layered structure illustrated at the top right of FIG. 7. Table 3 again summarizes the average and standard deviation of the measured Jsc, Voc, FF, and PCE performance of the measured devices.Table 3: 0.1 wt.% PMMA Perovskite performance measurementsJsc(mA / cm2) Voc(V) FF(%) PCE(%)Average -22.69 1.11 60.46 15.18SD 0.5 0.04 2.56 0.85

[0110] FIG. 8 shows J-V curves of a perovskite solar cell including 5 wt% of PMMA in the SnO2 liquid composition, in accordance with an embodiment. Again, the graph shows the J-V curves obtained from measurement of multiple devices, including a layered structure illustrated at the top right of FIG. 8. Table 4 again summarizes the average and standard deviation of the measured J, V, FF, and PCE performance of the measured devices.Table 4: 5 wt.% PMMA Perovskite performance measurementsJsc(mA / cm2) Voc(V) FF(%) PCE(%)Average -20.64 1.08 61.27 13.761SD 1.61 0.0109 5.74 1.84

[0111] Notably, the power conversion efficiency (PCE) peaks at 0.1 wt% PMMA, in the present embodiment, indicating that higher concentrations may compromise the layer's performance, while lower concentrations may not provide sufficient benefit. This hypothesis was confirmed by the results as shown in FIG. 9, in the present embodiment.

[0112] In addition to the additive compositions already discussed in this application, several other modifications and extensions of the disclosed technology may be considered. While the embodiments discussed above focus on polymer and metal oxide systems, it is conceivable that future embodiments may explore polymer and metal oxide alloy formulations, for example, to further enhance performance. Such expanded systems are considered to form a part of the present disclosure.

[0113] For example, ink rheology optimization is another area of interest, particularly for adapting the formulation to different scalable coating techniques such as inkjet, slot-die, or gravure printing. These changes may be achieved through additive engineering, solvent systemAttorney Docket No.: 117442-1557010-000110WOmodifications, or even adjustments to coating equipment or parameters, to name a few possible approaches.

[0114] Further device performance improvements may be achieved through pre- or postdeposition treatments, including thermal annealing, photo-induced treatments, plasma exposure, solvent vapor exposure, chemical passivation, or multi-layer deposition strategies. These approaches could further optimize interfacial properties and charge transport.

[0115] Integration of passivation strategies may further enhance the embodiments described herein. While interfacial engineering is well-established in perovskite development, direct embedding of passivation agents into the liquid metal oxide nanoparticle compositions or applying them as co-deposited or post-treated surface modifiers may be particularly helpful in improving device performance, in certain embodiments. These treatments may be aimed at reducing interfacial recombination losses and improving stability under operational conditions.

[0116] Additional modifications may include, for example, incorporating stability-enhancing agents and / or surface-functionalizing components to mitigate degradation due to moisture or heat. While these changes may arise from compositional adjustments, their purpose is to improve longterm device reliability and module-level durability.

[0117] As used herein, the recitation of “at least one of A, B and C” is intended to mean “either A, B, C or any combination of A, B and C ” The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0118] The terms and expressions employed herein are used as terms and expressions of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described or portions thereof. Each of the various elements disclosed herein may be achieved in a variety of manners. This disclosure should be understood to encompass each such variation, be it a variation of an embodiment of any apparatus embodiment, a method or process embodiment, or even merely a variation of any element of these. Particularly, it should be understood that the words for each element may be expressed by equivalent apparatus terms or method terms, even if only the function or result is the same. Such equivalent, broader, or even more generic terms should beAttorney Docket No.: 117442-1557010-000110WOconsidered to be encompassed in the description of each element or action. Such terms can be substituted where desired to make explicit the implicitly broad coverage to which this invention is entitled.

[0119] As but one example, it should be understood that all action may be expressed as a means for taking that action or as an element which causes that action. Similarly, each physical element disclosed should be understood to encompass a disclosure of the action which that physical element facilitates. Regarding this last aspect, by way of example only, the disclosure of a “protrusion” should be understood to encompass disclosure of the act of “protruding,” whether explicitly discussed or not, and, conversely, were there only disclosure of the act of “protruding,” such a disclosure should be understood to encompass disclosure of a “protrusion.” Such changes and alternative terms are to be understood to be explicitly included in the description.

Claims

Attorney Docket No.: 117442-1557010-000110WOWHAT IS CLAIMED IS:

1. A liquid composition for forming a charge transport layer comprising: an additive, wherein the additive comprises a polymeric material, a carbon-based material, and / or a reactive monomer, and is present in an amount from 0.01 wt.% to 49 wt.%, based on a total weight of the composition;a plurality of metal oxide nanoparticles, wherein at least a portion of the nanoparticles comprise one or more ligand-stabilized functionalizations; anda solvent;wherein the plurality of metal oxide nanoparticles are homogenously dispersed in the composition.

2. The composition of claim 1, wherein the additive comprises a conducting or semiconducting material, an insulating polymer or binder, reactive monomers, or combinations thereof.

3. The composition of claim 1, wherein the additive comprises polymethyl methacrylate (PMMA), polyaniline, carbon 60 (C60), phenyl-C61 -butyric acid methyl ester (PCBM), graphene, poly(2,3-dihydrothieno-l,4-dioxin)-poly(styrenesulfonate) (PEDOT:PSS), poly(3 -hexyl thiophene) (P3HT), polyethylenimine (PEI), polyethyleneimine ethoxylated (PEIE), polyvinylpyrrolidone (PVP), carbon nanotubes (CNTs), reduced graphene oxide (rGO), polyvinyl alcohol (PVA), polystyrene (PS), polyethylene glycol (PVG), polyacrylic acid (PAA), combinations thereof, or reactive monomers thereof.

4. The composition of claim 1, wherein the plurality of metal oxide nanoparticles comprise SnCL, NiOx, CuO, MoOx, or combinations thereof.

5. The composition of claim 1, wherein the metal oxide nanoparticles comprise a spherical shape.

6. A method for producing a charge transport layer, the method comprising: functionalizing hydrous metal oxide nanoparticles with a ligand to form ligand-stabilized metal oxide nanoparticles,combining the ligand-stabilized metal oxide nanoparticles with an additive, dispersing the combined functionalized metal oxide nanoparticles and the additive into a solvent to form a homogenous dispersiondepositing a layer of the homogenous dispersion onto a surface,Attorney Docket No.: 117442-1557010-000110WOforming the charge transport layer.

7. The method of claim 6, further comprising removing some or all of the solvent to form a thin film, wherein the thin film, after removal of the solvent, comprises a thickness of 60 nm or less.

8. The method of claim 7, wherein the layer of the homogenous dispersion is treated with heat, UV, or environmental exposure to form the thin film.

9. The method of claim 8, wherein the layer of the homogenous dispersion is treated at a temperature from 25°C to 165°C.

10. The method of claim 8, wherein the layer of the homogenous dispersion is treated for a minimum of 10 minutes.

11. The method of claim 6, wherein the layer of the homogeneous dispersion is deposited with spin coating, blade coating, slot-die coating, gravure printing, inkjet printing, or combinations thereof.

12. A metal oxide nanocomposite for a solar cell, comprising:an additive, wherein the additive comprises a polymeric material, a carbon-based material, and / or a reactive monomer, and is present in an amount from 0.01 wt.% to 49 wt.%, based on a total weight of the nanocomposite; anda plurality of metal oxide nanoparticles, wherein at least a portion of the nanoparticles comprise one or more ligand-stabilized functionalizations; andwherein the plurality of metal oxide nanoparticles are homogenously dispersed in the nanocomposite; andwherein the nanocomposite comprises a thin film.

13. The metal oxide nanocomposite of claim 12, wherein the nanocomposite comprises a total thin film volume, and wherein less than 40% of the total thin film volume comprises void space.

14. The metal oxide nanocomposite of claim 12, wherein the additive comprises polymethyl methacrylate (PMMA), polyaniline, carbon 60 (C60), phenyl-C61 -butyric acid methyl ester (PCBM), graphene, poly(2,3-dihydrothieno-l,4-dioxin)-poly(styrenesulfonate) (PEDOT:PSS), poly(3 -hexylthiophene) (P3HT), polyethylenimine (PEI), polyethyleneimine ethoxylated (PEIE), polyvinylpyrrolidone (PVP), carbon nanotubes (CNTs), reduced grapheneAttorney Docket No.: 117442-1557010-000110WOoxide (rGO), polyvinyl alcohol (PVA), polystyrene (PS), polyethylene glycol (PVG), polyacrylic acid (PAA), combinations thereof, or reactive monomers thereof.

15. The metal oxide nanocomposite of claim 12, wherein the plurality of metal oxide nanoparticles comprise SnCh, NiOx, CuO, MoOx, or combinations thereof .

16. A solar cell comprising the metal oxide nanocomposite of claim 12.

17. The solar cell of claim 16, wherein the solar cell comprises a perovskite solar cell comprising:a glass layer;a hole transport layer deposited on the glass layer;an interface layer deposited on the hole transport layer;a perovskite layer deposited on the interface layer; andthe metal oxide nanocomposite layer deposited on the perovskite layer.

18. The solar cell of claim 17, further comprising an electrode layer disposed over the nanocomposite layer, wherein the electrode layer comprises silver (Ag) ITO, gold (Au), carbon, or copper (Cu).

19. The solar cell of claim 17, wherein the metal oxide nanocomposite layer comprises an electron transport layer.

20. The solar cell of claim 17, wherein the solar cell comprises a power conversion of greater than or about 15% per 0.1 cm2.

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