WO2017214633A1 - Copolymères de chalcogène - Google Patents

Copolymères de chalcogène Download PDF

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Publication number
WO2017214633A1
WO2017214633A1 PCT/US2017/037062 US2017037062W WO2017214633A1 WO 2017214633 A1 WO2017214633 A1 WO 2017214633A1 US 2017037062 W US2017037062 W US 2017037062W WO 2017214633 A1 WO2017214633 A1 WO 2017214633A1
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copolymer
metal
chalcogen
sulfur
nanoparticles
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PCT/US2017/037062
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Hugh Hillhouse
Ian Larson BRALY
Christine Keiko LUSCOMBE
Trevor Martin
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University Of Washington
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/60—Selection of substances as active materials, active masses, active liquids of organic compounds
    • H01M4/602—Polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/581—Chalcogenides or intercalation compounds thereof
    • H01M4/5815—Sulfides
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/10—Organic polymers or oligomers
    • H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/10—Organic polymers or oligomers
    • H10K85/151—Copolymers
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
    • H10K30/30—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation comprising bulk heterojunctions, e.g. interpenetrating networks of donor and acceptor material domains
    • H10K30/35—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation comprising bulk heterojunctions, e.g. interpenetrating networks of donor and acceptor material domains comprising inorganic nanostructures, e.g. CdSe nanoparticles
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
    • H10K30/50—Photovoltaic [PV] devices
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/549—Organic PV cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • Thin-film semiconductor materials find use in a variety of applications, including photovoltaic (PV) devices.
  • Thin film solar cells of suitable efficiency have been fabricated from thin films of CuInGaSe 2 (CIGSe) and CdTe.
  • CGSe CuInGaSe 2
  • CdTe CuInGaSe 2
  • many currently- used methods of manufacturing such thin films rely upon costly and difficult steps such as vapor-deposition.
  • some solution-phase methods of manufacturing have been developed, which rely upon highly-reactive and dangerous reagents like hydrazine.
  • a copolymer in one aspect, includes a plurality of chalcogen constitutional units and a plurality of a chain-extending units.
  • a bulk material that includes a copolymer as described herein.
  • surface of a substrate includes a copolymer as described herein.
  • a solution in another aspect, includes a copolymer as described herein, and a metal precursor.
  • a method of forming a metal-chalcogen film includes: depositing a metal complex and a copolymer as disclosed herein onto a substrate; and
  • a nanoparticle that includes a copolymer as described herein.
  • a nanoparticle in another aspect includes a chalcogenide material, wherein a copolymer as described herein is used as a chalcogen source for the chalcogenide material.
  • nanoparticle is provided that is formed within a copolymer as described herein.
  • a nanoparticle is provided that is formed in solution with a copolymer as disclosed herein and a metal complex.
  • FIGURE 1 Elemental sulfur transitions to a liquid diradical state once heated to around 150 °C. Further heating beyond 160 °C will cause the sulfur diradical chains to polymerize, producing a solid polymeric material, b) Images of sulfur diradical polymerization process, where the sulfur is heated from room temperature (RT) and cooled.
  • RT room temperature
  • FIGURE 2A Procedure for synthesizing the sulfur copolymer. Oligomeric liquid sulfur diradicals are reacted with a methylstyrene monomer to produce the sulfur copolymer.
  • FIGURE 2B Reaction scheme for producing sulfur copolymer.
  • FIGURE 3 Procedure for synthesizing CdS nanoparticles using a sulfur copolymer.
  • FIGURE 4 Procedure for removing sulfur copolymer and isolating CdS nanoparticles.
  • FIGURE 5 a) Image of sulfur copolymer, b) Image of sulfur copolymer and CdS nanoparticle composite powder.
  • FIGURE 6. a) TEM images depicting nanoparticle growth within the liquid sulfur copolymer, b) Nanoparticle growth profile; the size of the nanoparticles was measured using TEM images.
  • FIGURE 7 UV-Vis spectra illustrating a redshift in absorbance as the CdS nanoparticles grow within the sulfur copolymer matrix.
  • FIGURE 8 a) TEM image of CdS nanoparticles with some of the sulfur copolymer removed, b) Magnified TEM image of the highlighted region, showing a clear planar spacing of 3.3 A. c) SAED pattern for CdS nanoparticle aggregates, d) TEM image of nanoparticle aggregates once the sulfur copolymer has been completely removed with inset EDS data.
  • FIGURE 9 XRD pattern for CdS nanoparticles drop-cast onto a molybdenum coated soda lime glass substrate.
  • FIGURE 10 1H NMR spectrum for the ligand-free CdS nanoparticles.
  • Reference spectra for conventional CdS nanoparticles with oleic acid and octadecylamine ligands (Standard CdS NP), the cadmium acetyl acetonate precursor (Cd(AcAc)) and the sulfur copolymer (Poly S) are also presented for comparison.
  • FIGURE 11 FTIR spectra for the ligand-free CdS nanoparticles. Standard CdS nanoparticles capped with oleic acid and octadecylamine, and the sulfur copolymer are also included for comparison.
  • FIGURE 12 Photoluminescence spectroscopy for sulfur copolymer and nanocomposite.
  • the nanocomposite exhibits a peak that is blue-shifted from the bulk bandgap of CdS (510 nm, 2.4 eV), while the sulfur copolymer exhibits comparatively little photoluminescence.
  • FIGURE 13 Absorbance spectroscopy for sulfur copolymer and nanocomposite.
  • the nanocomposite exhibits a significantly enhanced absorption peak in comparison to the sulfur copolymer alone. Both materials have equal concentrations while in dispersion.
  • FIGURE 14 Absorbance and Photoluminescence spectroscopy of ligand-free CdS nanoparticles.
  • the PL data show a broad peak centered at 510 nm.
  • the UV-Vis-NIR data show a broad absorption curve with a weak absorption shoulder in the range of 450-550 nm.
  • FIGURE 15 TEM images of CIS nanoparticles synthesized using the sulfur copolymer. The nanoparticles exhibit a multifarious platelet structure in the 100 nm size range.
  • FIGURE 16 XRD spectra of CIS nanoparticle film synthesized using the sulfur copolymer prior to annealing.
  • FIGURE 17 XRD diffraction pattern of CISSe film post annealing/selenization made from sulfur copolymer based CIS nanoparticles.
  • FIGURE 18 Raman spectrum of CISSe film post annealing/selenization made from sulfur copolymer based CIS nanoparticles.
  • FIGURE 19 Cross sectional SEM image of CISSe films made using CIS nanoparticles synthesized within a sulfur copolymer and annealed at 500 °C in the presence of Se vapor.
  • FIGURE 20 PL spectrum of CISe film post annealing/selenization made from sulfur copolymer based CIS nanoparticles.
  • FIGURE 21 a), b), c), and d) TEM images of CISSe nanoparticles synthesized using the selenium sulfide terpolymer. e) Fourier transform of the image presented in d) showing a diffraction pattern consistent with the tetragonal crystal structure of chalcopyrite.
  • FIGURE 22 a) and b) SEM images of CISSe nanoparticle films with selenium sulfide terpolymer residue prior to annealing, c) Elemental maps from EDS spectra for region shown in b).
  • FIGURE 23 XRD patterns for CISSe films before and after 250 °C 1 hr annealing.
  • FIGURE 24 Raman spectrum for CISSe nanoparticle films after 1 hour of annealing at 250 °C.
  • FIGURE 25 a) and b) SEM images of CISSe nanoparticle films with selenium sulfide terpolymer residue after low-temperature annealing, c) Elemental maps from EDS spectra for region shown in b).
  • FIGURE 26 PL spectrum for CISSe nanoparticle films after 1 hour of annealing at 250 °C. The bandgaps of pure CuInS 2 and CuInSe 2 are presented for comparison. The detector used has an abrupt reduction in sensitivity at approximately 900 nm.
  • FIGURE 27 Schematic representation of a low-temperature, completely solution- processed method for printing CuInSe 2 PV absorber layers using an ink that comprises of CuInS x Se 2-x nanoparticles coated with a selenium sulfide terpolymer.
  • FIGURE 28 illustrates a representative copolymer having organic monomer units along with chalcogen sulfur and selenium units.
  • FIGURE 28 further includes photographs of chalcogen powder, representative chalcogen copolymer solids, and representative chalcogen copolymer solutions.
  • FIGURE 29 illustrates a schematic of stepwise formation of a chalcogen- copolymer-containing photovoltaic thin film, including characterization of the film by optical microscopy, scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDS).
  • SEM scanning electron microscopy
  • EDS energy dispersive x-ray spectroscopy
  • FIGURES 30A-30H Characterization of CuInSe2 photovoltaic crystals formed using a representative selenium polymer.
  • Scanning electron microscopy (SEM) images (FIGURES 30A and 3 OB), concurrent energy dispersive x-ray spectroscopy (EDS) images (FIGURES 30C-30E), x-ray diffraction (XRD; FIGURE 3 OF) and Raman spectroscopy (FIGURE 30G) illustrate it is possible to produce CuInSe 2 crystals using a selenium polymer.
  • the photoluminescence (PL) data (FIGURE 3 OH) demonstrates a bandgap of 1.0 eV.
  • copolymers comprising a plurality of chalcogen constitutional units and a plurality of chain-extending units.
  • the copolymers are therefore hybrid chalcogen-organic copolymers.
  • the properties of the copolymers are tunable through choice of chalcogen, choice of chain-extending unit monomer, and the relative amounts of each component.
  • compositions that include the copolymers; surfaces that include the copolymers, solutions (e.g., "inks") that include the copolymers; methods of forming the copolymers, methods of forming films using or incorporating the copolymers, nanoparticles that include the copolymers, and devices incorporating the copolymers.
  • the copolymers can be used as both the chalcogen source and solvent in the synthesis of semiconducting nanoparticles (e.g., CdS nanoparticles), thereby producing such nanoparticles without organic ligands, the conventional approach.
  • semiconducting nanoparticles e.g., CdS nanoparticles
  • constitutional unit of a polymer refers to an atom or group of atoms in a polymer, comprising a part of the chain together with its pendant atoms or groups of atoms, if any.
  • the constitutional unit can refer to a repeat unit.
  • the constitutional unit can also refer to an end group on a polymer chain.
  • the constitutional unit of polyethylene glycol can be -CH 2 CH 2 0- corresponding to a repeat unit, or -CH 2 CH 2 OH corresponding to an end group.
  • chain extending agent refers to a molecule that chemically links chalcogen constitutional units together, thereby increasing the molecular weight of the copolymer.
  • the chain-extending agent is also referred to herein as a "monomer” or "organic monomer.” It should be appreciated that while the copolymers may be referred to in terms of the monomers used to form them, the chemical structure of the copolymer includes the monomer in polymerized form.
  • repeat unit corresponds to the smallest constitutional unit of a copolymer, the repetition of which constitutes a regular macromolecule (or oligomer molecule or block).
  • a copolymer in one aspect, includes a plurality of chalcogen constitutional units and a plurality of a chain-extending units.
  • a representative copolymer is illustrated in FIGURE 2B, which schematically illustrates a sulfer- methylstyrene copolymer.
  • the sulfur blocks are the plurality of chalcogen constitutional units and the methlstyrene is the chain-extending unit.
  • FIGURE 28 illustrates another representative copolymer, formed using both sulfur and selenium chalcogens and a monomer configured to coordinate with metal cations to provide miscibility with metal-precursor inks.
  • the copolymer will have properties defined in part by its composition.
  • the specific moieties of the monomer can also add additional functionalities to the polymer.
  • using N,N-dimethylvinylbenzylamine allows the polymers to directly coordinated with metal cations and allows the polymers to be miscible with solutions of metal salts.
  • the general trend is that different monomers can be used to impart the polymers with specific properties depending on the application.
  • different monomers can make the polymers soluble in other solvents, can be designed to produce targeted chemical reactions, the ability to coordinate with other materials, or can be designed to facilitate the reactions with the chalcogens to produce the polymer initially.
  • the copolymer is a liquid at about 20 °C. In another embodiment, the copolymer is a liquid at about 50 °C. In another embodiment, the copolymer is a liquid at about 100 °C. In another embodiment, the copolymer is a liquid at about 150 °C.
  • the chalcogen constitutional units comprise at least 50 atomic percent of the copolymer. In one embodiment, the chalcogen constitutional units comprise at least 60 atomic percent of the copolymer. In one embodiment, the chalcogen constitutional units comprise at least 70 atomic percent of the copolymer. In one embodiment, the chalcogen constitutional units comprise at least 80 atomic percent of the copolymer. In one embodiment, the chalcogen constitutional units comprise at least 90 atomic percent of the copolymer. In one embodiment, the chalcogen constitutional units comprise at least 95 atomic percent of the copolymer.
  • the molecular ratio of chalcogenxhain-extending units is in the range of 1 :2 to 100: 1. In one embodiment, the molecular ratio of chalcogenxhain- extending units is in the range of 2: 1 to 6: 1, which typically provides optimized solubility and reactivity.
  • One particularly notable exemplary copolymer is a 4: 1 Se to monomer polymer with 100% Se (chalcogen) polymer and ⁇ , ⁇ -dimethylvinylbenzylamine as the monomer.
  • Another exemplary copolymer is a 6: 1 S to monomer polymer, with 100% S (chalcogen) and ⁇ , ⁇ -dimethylvinylbenzylamine as the monomer.
  • Further examples include a 4: 1 Se/S to monomer ratio polymer with 2: 1, 1 : 1, 1 :2 or 1 :3 Se to S ratios with N,N- dimethylvinylbenzylamine as the monomer.
  • the molecular ratio of chalcogenxhain-extending units about 4: 1.
  • the plurality of chalcogen constitutional units comprise at least two chalcogens selected from the group consisting of oxygen, sulfur, selenium, and tellurium. In a further embodiment, the chalcogen constitutional units comprise both sulfur and selenium. In yet a further embodiment, the ratio of selenium to sulfur is about 3 : 1. In yet a further embodiment, the ratio of selenium to sulfur is about 2: 1. In yet a further embodiment, the ratio of selenium to sulfur is about 1 : 1. In yet a further embodiment, the ratio of selenium to sulfur is about 1 :2. In yet a further embodiment, the ratio of selenium to sulfur is about 1 :3.
  • the chalcogen constitutional units comprise selenium as the only chalcogen.
  • Se-only (i.e., only Se chalcogen) copolymers are that they can be used to produce low-bandgap materials. There are very few other options to do this using solution processing.
  • the chalcogen constitutional units comprise sulfur as the only chalcogen.
  • S-only (i.e., only S chalcogen) copolymers is that it is possible to make an S-only copolymer that is a liquid at room temperature. Such embodiments are with a high ratio of monomer, in the range of 2: 1 S to monomer or greater.
  • sulfur is from 15 to 25 atomic percent of the copolymer. In one embodiment sulfur is about 20 atomic percent of the copolymer. In one embodiment sulfur is from 75 to 85 atomic percent of the copolymer. In one embodiment sulfur is about 80 atomic percent of the copolymer.
  • the chain-extending units comprise repeat units derived from the polymerization of a monomer comprising an unsaturated moiety.
  • the chain-extending units comprise repeat units repeat units derived from the polymerization of an ethylenically unsaturated monomer.
  • Functionalized styrene monomers are a genus of monomers that are of particular interest.
  • the chain-extending units are mono-vinylic.
  • Such chain extending agents are advantageous because, when copolymerized with the chalcogen constitutional units they do not tend to crosslink the polymers. Accordingly, the bulk materials have lower melting temperatures and are liquids at lower temperatures.
  • Such copolymers are useful as solvents, making ligand-free nanoparticles, and solvent processing and/or selenizing of metal-containing thin films, as described further herein.
  • metal-sulfide nanoparticle synthesis cannot be easily completed with a divinylic cross-linking monomer in the sulfur source because such a monomer produces a highly viscous material due to the high molecular weight polymers produced and the cross-linking reactions taking place.
  • a single vinylic group monomer(e.g., methylstyrene)-based sulfur copolymer promotes depolymerization and the formation of oligomeric radicals that cause the solution to remain a liquid at elevated temperatures and can subsequently react with the metal precursors.
  • the chain extending agent comprises a divalent metal cation.
  • the divalent metal cation is selected from the group consisting of Be 2+ , Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ , Cu 2+ , and Zn 2+ .
  • the chain-extending units are derived from the polymerization of a monomer selected from the group consisting of styrene, methyl styrene, ethyl styrene, vinylnaphthalene, vinylanthracene, N,N- dimethylvinylbenzylamine, vinylbenzylamine, vinylpyridine, nitrostyrene, methoxystyrene, vinylanisole, vinylbenzyl alcohol, vinylbenzoic acid, cyanostyrene, acetoxy styrene, vinylbenzoate, fluorostyrene, and chlorostyrene.
  • a monomer selected from the group consisting of styrene, methyl styrene, ethyl styrene, vinylnaphthalene, vinylanthracene, N,N- dimethylvinylbenzylamine, vinylbenzylamine, vinylpyridine, nitrostyrene, methoxysty
  • the chain-extending units are configured to provide enhanced solubility in a solvent.
  • FIGURE 28 illustrates an exemplary copolymer formed using DMVBA, S, and Se.
  • the terminal amino group on the monomer provides for both enhanced solubility in certain solvents, which aids in the formation of inks that include metal precursors, and also provides enhanced coordination between the copolymer and metal cations in such a metal precursor ink.
  • the chain- extending units are configured to provide enhanced coordination between the copolymer and metal cations.
  • the copolymer further includes a chain-terminating end group.
  • a chain termination agent is a molecule that reacts with a chalcogen constitutional unit to form a terminal end group, thereby terminating polymerization. This is useful to control polymer length and, as a result, certain properties related to polymer length.
  • the chain termination agent is a halogen.
  • the chain terminating agent releases monovalent cations upon terminating polymerization.
  • such monovalent metal cation chain terminating agents are selected from the group consisting of Li + , Na + , K + , and Rb + .
  • Such chain termination agents include any chemical that dynamically breaks the chain and temporarily terminates it.
  • Such a copolymer provides a bandgap at 1.34 eV at Shockley-Queisser max.
  • a bulk material in another aspect, includes a copolymer as described herein.
  • the bulk material includes at least the copolymer.
  • the bulk material includes the copolymer an at least one additional component, such as a plasticizer or a cation configured to form a complex with the polymer.
  • the bulk material further comprises a plasticizer, wherein the plasticizer is an additive to the bulk material that increases the fluidity or plasticity of a polymer.
  • plasticizers include organic solvents, such as toluene, used to solvate the copolymers. By controllably removing the solvent from the copolymer, an amount of solvent can be left within the copolymer matrix and acts as a plasticizer.
  • Plasticizers also include other polymers or oligomers that disrupt the copolymer matrix, traditional plasticizers can also be used, such as phthalates.
  • the bulk material further comprises the copolymer coordinated with metal cations.
  • metal complexes include metal chlorides, metal iodides, metal bromides, metal acetates, metal acetylacetonates, metal nitrates, and metal amines.
  • Representative metals include copper, indium, gallium, zinc, tin, cadmium, lead, silver, gold, bismuth, iron, vanadium, chromium, manganese, cobalt, nickel, molybdenum, and tungsten.
  • the metal complex comprises a metal cation and an organic or inorganic anion.
  • the organic anion is selected from the group consisting of acetate, acetylacetonate, and thiocyanate.
  • the inorganic anion is selected from T, Br “ , CI “ , [BF 4 ] “ , [PF 6 ] “ , S “2 , Se “2 , and O “2
  • the bulk material further comprises the copolymer coordinated with non-metal cations.
  • Representative non-metallic complexes include germanium, silicon, antimony, arsenic, phosphorus, sodium, potassium, and lithium.
  • surface of a substrate includes a copolymer as described herein.
  • a copolymer on the surface of a substrate, such as a thin film coating.
  • the surface comprises a film of the copolymer disposed on a substrate.
  • the surface further comprises metal complexes configured to form complexes with the copolymer.
  • metal complexes include metal chlorides, metal iodides, metal bromides, metal acetates, metal acetylacetonates, metal nitrates, and metal amines.
  • Representative metals include copper, indium, gallium, zinc, tin, cadmium, lead, silver, gold, bismuth, iron, vanadium, chromium, manganese, cobalt, nickel, molybdenum, and tungsten.
  • the surface further comprises the copolymer coordinated with non-metal cations.
  • Representative non-metallic complexes include germanium, silicon, antimony, arsenic, phosphorus, sodium, potassium, and lithium.
  • the surface includes metal complexes that are metal chalcogenide nanoparticles.
  • Representative nanoparticle materials include CdS, CdSe, CdTe, ZnS, ZnSe, MoS 2 , WS 2 , CuInSe 2 CuInS 2 , CuInGaS 2 CuInGaSe 2 , Cu 2 ZnSnS 4 ,
  • the metal complex is a perovskite precursor or a perovskite.
  • a perovskite can be used to solution-produce functional materials, using mild processing conditions, such as the photovoltaic CuInSe2, when reacted with a selenium copolymer according to embodiments disclosed herein.
  • the perovskite ( H 4 ) 2 CuInCl 6 can be converted to CuInSe 2 using selenium copolymers as disclosed.
  • the surface includes metal complexes that are a perovskite or perovskite precursor having the formula of AB n X 3 , A 2 B I B II X 6 , or A 4 B I 2 B II B IV Xi2, wherein
  • A is selected from a monovalent organic cation and a monovalent inorganic cation;
  • B 1 is a monovalent metal cation;
  • B n is a divalent metal cation
  • B ni is a trivalent metal cation
  • B IV is a tetravalent metal cation
  • each X is selected from a halide and molecular anion.
  • Exemplary B 1 cations include Cu, Ag.
  • Exemplary B m cations include In, Ga, Al, Bi, and Sb.
  • Exemplary B IV cations include Si, Ge, Sn, Hf, Ti, and Pt.
  • Representative perovskite compositions include NH 4 CdCl 3 , CH 3 NH 3 CdCl 3 , H 4 ZnCl 3 , CH 3 H 3 ZnCl 3 , H 4 HgCl 3 , CH 3 H 3 HgCl 3 , ( H 4 ) 2 CuInCl 6 , ( H 4 ) 4 CuZn SnCli2, (CH 3 H3) 2 CuInCl6, (CH 3 H3) 4 Cu 2 ZnSnCli2, ( H 4 ) 2 AgInCl 6 ,
  • X is selected from F “ , CI “ , Br “ , ⁇ , CSN “ , [BF ] “ , and [PF 6 ].
  • Exemplary cations include H + , Li + , Na + , K + , Rb + , Cs + , NH 4 + , CH 3 NH 3 + .
  • Exemplary anions include F “ , CI “ , Br “ , ⁇ , CN “ , NCS “ , N 3 “ , BF “ , and PF 6 “ .
  • the organic cations (A) are selected from ammonium and methyl ammonium. In certain embodiments, the monovalent inorganic cations (A) are selected from Group I metal cations.
  • A comprises an ammonium group.
  • A is selected from the group consisting of [CH 3 NH 3 ] + , [NH 4 ] + , [(NH 2 ) 3 C] + , [(NH 2 ) 2 CH] + .
  • A is doped with a Group I monovalent metal cation, for example and without limitation, Li + , Na + , K + , Rb + , and Cs + .
  • the perovskite precursor has the formula AB n X 3 and B n is selected from the group consisting of Mg , Cd , Zn , Pb , and Hg .
  • the perovskite precursor has the formula A ⁇ B 111 ⁇ ; B 1 is selected from the group consisting of Cu + and Ag + ; and B m is selected from the group consisting of In +3 , Ga +3 , Al +3 , and Sb +3 .
  • the perovskite chemical precursor has the formula A 4 B I 2 B II B IV X 12 ; B 1 is selected from the group consisting of Cu + and Ag + ; B n is selected from the group consist of Mg , Cd , and Zn ; and B is selected from the group consisting of Sn +4 and Ge +4 .
  • the copolymer is incorporated into a device or a device component, such as an electrode or a photovoltaic element.
  • the substrate is an electrode.
  • the substrate is a transparent conducting electrode.
  • the copolymer is applied to the electrode substrate and can be used on its own or combined with other materials, such as metal cations, to form functional materials such as photovoltaic materials.
  • the substrate is a portion of an optoelectronic device.
  • the optoelectronic device is a photovoltaic device.
  • the optoelectronic device is selected from the group consisting of a photovoltaic device, a light-emitting diode, a photodetector, a photomultiplier, and a photoresistor.
  • the optoelectronic device is a field-effect transistor.
  • the substrate comprises molybdenum-coated soda lime glass. Solutions Including the Copolymers
  • a solution in another aspect, includes a copolymer as described herein, and a metal precursor.
  • the solutions of the present invention are useful in depositing on substrates to make thin films, including semiconductor and other metal- containing thin films.
  • the metal precursors of this aspect are those described elsewhere herein.
  • Representative metal precursor complexes include metal chlorides, metal iodides, metal bromides, metal acetates, metal acetylacetonates, metal nitrates, and metal amines.
  • Representative metals include copper, indium, gallium, zinc, tin, cadmium, lead, silver, gold, bismuth, iron, vanadium, chromium, manganese, cobalt, nickel, molybdenum, and tungsten.
  • the metal precursor complex comprises a metal cation and an organic or inorganic anion.
  • the organic anion is selected from the group consisting of acetate, acetyl acetonate, and thiocyanate.
  • the inorganic anion is selected from T, Br “ , CI “ , [BF 4 ] “ , [PF 6 ] “ , S “2 , Se “2 , and O “2
  • copolymer "inks” can be used to "print” material that incorporates or is formed using the copolymer.
  • FIGURE 29 illustrates the formation of a copolymer ink by combining a "metals solution” and a “polymer solution” (that is a solution of copolymer) and coating the combined solution on a substrate as a precursor. Heating forms nanoparticles from the complex of the copolymer and metal components. After washing away the excess polymer an anneal step allows crystal growth to form CuInSe2, a photovoltaic material.
  • the solution further includes a plasticizer.
  • Plasticizers were discussed previously and all of the described plasticizers can be incorporated into the solutions, assuming solution compatibility.
  • the solution does not include a solvent.
  • the polymer is in liquid form at certain temperatures, based on its composition. If the copolymer is in liquid form, no solvent is needed to form the solution. In such an embodiment, the copolymer is effectively the solvent for the metal precursor.
  • the solution further includes a solvent.
  • Representative solvents include any that can solvate both the copolymer and the metal precursor.
  • Exemplary solvents include toluene.
  • the solvents can be used in any manner known to those of skill in the art, including inkjet printing, blade coating, drop coating, and screen printing.
  • a method of forming a metal-chalcogen film includes:
  • the metal complex and the copolymer may be deposited according to any method known in the art.
  • the metal complex and the copolymer are deposited as part of a solution. They may be deposited in separate solutions or as part of a common solution.
  • the solution may be a solution as described further herein.
  • the annealing step includes an anneal at the relatively low minimum temperature of 30 °C.
  • One benefit of the provided methods and materials is the ability to anneal at such low temperatures, which allows for reduced time and energy, as well as allowing for more compatible materials to be processed along with the copolymer (e.g., because temperature-sensitive materials can be used that would be damaged at higher temperatures).
  • the annealing step occurs without reaching a temperature greater than 500 °C. In one embodiment, the annealing step occurs without reaching a temperature greater than 250 °C. In one embodiment, the annealing step occurs without reaching a temperature greater than 100 °C.
  • the metal complex is a perovskite precursor as described further herein.
  • FIGURE 29 provides an example of an exemplary method according to this aspect, where a solution is used to deposit a metal-copolymer film that is then annealed to generate nanoparticles and then grow crystals.
  • the copolymer and the metal complex can be deposited together as a single solution, separately, and/or sequentially to provide various effects, including films with a gradient of one or more components.
  • the metal complex is deposited separately and before the copolymer.
  • the copolymer is deposited separately and before the metal complex.
  • the metal complex and copolymer may be deposited several times upon the substrate in order to provide a thicker layer of each.
  • the metal complex is deposited a plurality of times to provide a metal-complex layer.
  • the copolymer is deposited a plurality of times to provide copolymer layer.
  • the metal complex and copolymer are deposited onto the substrate from a mixture comprising the metal complex and the copolymer.
  • This embodiment utilizes an "ink” solution as disclosed previously.
  • the metal complex and copolymer are deposited onto the substrate so as to form a gradient metal copolymer film wherein the ratio of chalcogen changes throughout the thickness of the gradient metal chalcogen film.
  • varying amounts of gallium and indium across the depth of a CuInGa(S,Se) 2 device can be used and/or varying amounts of S to
  • the film will have a thickness of 100 nm to 2 microns. In one embodiment the film is about 1 micron. A 1 micron thickness is optimal for PV devices formed from the copolymers.
  • the metal complex and the copolymer are deposited onto the substrate so as to form a gradient metal copolymer film wherein the metal stoichiometry changes throughout the thickness of the gradient metal chalcogen film.
  • the metal complex and the copolymer are deposited onto the substrate so as to form a gradient metal copolymer film wherein the ratio of chalcogen changes and the metal stoichiometry changes throughout the thickness of the gradient metal chalcogen film.
  • the gradient metal copolymer film has decreasing chalcogen content as it extends away from the substrate.
  • the gradient metal copolymer film has increasing chalcogen content as it extends away from the substrate.
  • the metal complexes are metal chalcogenide nanoparticles.
  • nanoparticles are discussed elsewhere herein, including below in greater detail.
  • nanoparticle in another aspect includes a copolymer as described herein.
  • nanoparticles can be formed within the disclosed copolymer and then the copolymer can be removed, giving access to the reactive nanoparticle surfaces. These surfaces can then be used as-is or further functionalized with other molecular species. This can provide the nanoparticles selective reactivity with certain molecules or to tune photonic properties. In the bare-nanoparticle-surface case, this can be used to make nanoparticles that easily aggregate together and are easily sintered to produce a bulk material.
  • a nanoparticle in another aspect includes a chalcogenide material, wherein a copolymer as described herein is used as a chalcogen source for the chalcogenide material.
  • a nanoparticle is provided that is formed within a copolymer as described herein.
  • Example 1 further describes such an aspect, referred to as a "nanocomposite" that includes nanoparticles formed using the copolymer and the copolymer surrounding the nanoparticles.
  • a composite is provided comprising a plurality of nanoparticles dispersed within a copolymer as disclosed herein.
  • a nanoparticle is provided that is formed in solution with a copolymer as disclosed herein and a metal complex.
  • Embodiments of this aspect include the descriptions herein of solutions ("inks”) and complexes formed between copolymers and metal complexes (or non-metal cations).
  • the nanoparticle contains no aliphatic ligands.
  • the copolymers are useful as solvents for synthesizing chalcogen-containing nanoparticles without the use of traditional organic ligands. The result is a compositionally different nanoparticle, having no aliphatic ligands.
  • FIGURES 10 and 11 provide NMR and FTIR (respectively) evidence of aliphatic-ligand-free CdS nanoparticles synthesized using exemplary copolymers.
  • the nanoparticle comprises a metal complex associated with the copolymer.
  • the nanoparticle is composed of any chalcogen components and any of the metals disclosed herein.
  • Representative metal complexes include metal chlorides, metal iodides, metal bromides, metal acetates, metal acetylacetonates, metal nitrates, and metal amines.
  • Representative metals include copper, indium, gallium, zinc, tin, cadmium, lead, silver, gold, bismuth, iron, vanadium, chromium, manganese, cobalt, nickel, molybdenum, and tungsten.
  • the nanoparticle can be of the form having any metal disclosed herein (A,B,C,D) and any chalcogen atom or ratio of chalcogen atoms (S, Se, Te).
  • binary metal-chalcogenides (example: CdSe): AxSy, AxSey, AxTey, AxSySez, AxTeySez, AxSyTez;
  • ternary metal-chalcogenides (example: CuInS2): AwBxSy, AwBxSey, AwBxTey, AwBxSySez, AwBxSyTez, AwBxTeySez;
  • quaternary metal-chalcogenides (example: Cu2ZnSnSe4): AvBwCxSy, AvBwCxSey, AvBwCxTey, AvBwCxSySez, AvBwC
  • the nanoparticle has a diameter of 3 nm to 500 nm.
  • the following examples are included for the purpose of illustrating, not limiting, the described embodiments.
  • Example 1 Ligand-Free Nanoparticles Synthesis with Sulfur Copolymer.
  • Elemental sulfur has a number of properties that can be utilized as starting points for the development of new materials.
  • elemental sulfur is heated to around 150 °C, it transitions from an S 8 structured ring to a liquid linearly structured sulfur diradical, as outlined in FIGURE la. If the liquid sulfur is heated further, the sulfur diradicals will react with each other and polymerize, producing a solid material.
  • FIGURE lb further illustrates this polymerization process, where an inverted vial containing heated sulfur shows that the polymer has solidified and as the polymer cools, it transitions back to the liquid state. This process is reversible, where the solid sulfur polymer can be cooled to induce depolymerization and the formation of a liquid, which can be further cooled to form S 8 rings.
  • FIGURE 2A The procedure for synthesizing the methylstyrene based sulfur copolymer is outlined in FIGURE 2A and the reaction scheme is presented in FIGURE 2B. Specifically, elemental sulfur (4 g, 124.8 mmol, S8, 99.5%), was placed in a 20 mL glass vial with a stir bar. The glass vial was capped with a septum and suspended in an oil bath. A needle connected to a Schlenk line was inserted through the septum to provide a nitrogen atmosphere for the synthesis.
  • the mixture was then heated to 150 °C with stirring, and once all of the sulfur reached the liquid state, a-methylstyrene (330 ⁇ ., 2.5 mmol, 99%, 50: 1 molar ratio of Sulfur atoms to monomer molecules) was injected into the solution through the septum. After injection, the solution was heated to 185 °C for 10 min. At this stage, the liquid polymer underwent a color change as the polymerization process occurred. The polymer was then cooled to room temperature (RT), producing a solid material.
  • RT room temperature
  • the procedure for synthesizing the CdS nanoparticles using the methylstyrene based sulfur copolymer is outlined in FIGURE 3. Specifically, sulfur copolymer (4.0 g, 116 mmol) was combined with cadmium acetyl acetonate (Cd(acac), 900 mg, 2.9 mmol 99.9%), in a three neck flask. The flask was subjected to several vacuum and nitrogen pump purge cycles. The flask was then filled with nitrogen and heated to 200 °C for 30 min with stirring after which the reaction mixture was cooled to RT. This synthesis technique produces a nanocomposite where the CdS nanoparticles are suspended within the excess sulfur copolymer.
  • Cd(acac) cadmium acetyl acetonate
  • the nanocomposite powder (200 mg) was dissolved in chloroform (20 mL) and ultrasonicated for 1 h. Chloroform (20 mL) was added to the solution, which was then separated into two 20 mL centrifuge tubes and centrifuged at 10k rpm for 15 min. The sulfur copolymer was then decanted from the settled nanoparticles. The nanoparticles were dispersed in chloroform and sonicated for 15 min, followed by another centrifugation step. This process was repeated until all of the orange colored sulfur copolymer was removed (4-5 repeats) (FIGURE 4). The final CdS nanoparticles were placed under high vacuum to remove all of the residual solvent.
  • FIGURE 5a shows an image of the sulfur copolymer synthesized using the steps outlined in section 1.3.1. Next, this sulfur copolymer was used to grow CdS nanoparticles in solution according to the steps outlined in section 1.3.2. Once cooled, the liquid solidified into a black nanocomposite powder that is easily processed, as depicted in FIGURE 5b.
  • a metal-sulfide nanoparticle synthesis cannot be easily completed with a divinylic cross-linking monomer such as DIB in the sulfur source, since this monomer produces a highly viscous material due to the high molecular weight polymers produced and the cross-linking reactions taking place.
  • DIB divinylic cross-linking monomer
  • the single vinylic group of the methylstyrene based sulfur copolymer promotes depolymerization and the formation of oligomeric radicals that cause the solution to remain a liquid at elevated temperatures and can subsequently react with the metal precursors.
  • FIGURE 8b shows a magnified image of the highlighted region in FIGURE 8a and exhibits a clear crystal plane spacing of 3.3 A, which is consistent with the (111) plane of zincblende CdS or the (002) plane of wurtzite CdS.
  • IGURE 8c shows the selected area electron diffraction pattern (SAED) for the CdS nanoparticles, which shows the presence of polycrystalline aggregates.
  • FIGURE 8d shows the CdS nanoparticles once all of the copolymer has been removed and the inset shows the EDS data, where a nearly 1 to 1 ratio of Cd to S atoms is seen, which indicates that the sulfur copolymer has been effectively removed and further confirms the formation of CdS nanoparticles.
  • X-ray diffraction XRD was performed to examine the crystal structure of the resulting nanoparticles (FIGURE 9). The diffraction pattern is consistent with the SAED pattern in FIGURE 9c and is consistent with the formation of wurtzite and zincblende structured CdS.
  • FIGURE 10 shows the 1H NMR spectra with several reference spectra, including standard OLA/oleic acid ligated CdS. Clearly, the spectra show that the nanoparticles do not possess conventional organic ligands.
  • the sulfur copolymer NMR does not show any protons coordinating at the methylstyrene vinyl functional group at 5-6 ppm, which supports the sulfur copolymer structure presented in FIGURE 27.
  • FIGURE 11 shows the powder FTIR spectra for the same samples, which also show that the nanoparticles do not have conventional organic ligands.
  • FIGURE 12 shows the absorbance of the particles while they are suspended within the sulfur copolymer matrix (nanocomposite).
  • FIGURE 13 shows the PL of the nanocomposite and the sulfur copolymer. Since the concentrations of each dispersion are equal for FIGURES 12 and 13, the data show that the nanocomposite exhibits an enhanced absorbance onset in comparison to only the sulfur copolymer that is blue-shifted from the bulk bandgap of CdS (510 nm, 2.4 eV).
  • the photoluminescence data presented in FIGURE 14 show that the nanocomposite exhibits a broad peak that is also blue-shifted from the bulk bandgap of CdS, while the sulfur copolymer peak is comparatively small.
  • the broad, blue-shifted nature of the PL spectra is likely due to quantum confinement effects that arise in CdS particles in the 2-5 nm size range, coupled with a relatively high level of nanoparticle size dispersity as seen in the TEM images, as well as the presence of surface-mediated sub-bandgap energy states.
  • FIGURE 14 shows both the UV- Vis and PL data.
  • the nanoparticles have a broad PL peak that is centred at the bulk bandgap of CdS and a correspondingly broad absorption spectrum with a small absorption edge that is in the range of 450-550 nm.
  • nanoparticles can be effectively ligated with chalcogenide surface species, although this process requires using hydrazine, which is a highly toxic and explosive liquid.
  • This work posits that the nanoparticles made using this method have similarly structured chalcogen species on the nanoparticle surface, although in comparison the method described herein is a simple, scalable, and nontoxic way to synthesize nanoparticles without the presence of organic ligands.
  • This Example establishes a unique method for utilizing elemental sulfur and presented a novel technique for directly synthesizing nanoparticles without conventional aliphatic ligands.
  • the Example began by developing a new sulfur copolymer that is simple to synthesize, easily processable and is a liquid at elevated temperatures.
  • This sulfur copolymer can be used as a high boiling point solvent and as a sulfur precursor to synthesize stabilized metal-sulfide nanoparticles that are suspended within a sulfur copolymer matrix.
  • the ligand-free nanoparticles Once the ligand-free nanoparticles are ready to be used, they can be separated from the sulfur copolymer.
  • This nascent ligand-free nanoparticle synthesis method can potentially be useful in a range of situations including future biomedical and photonic materials applications, where the presence of aliphatic coordinating ligands is otherwise detrimental.
  • the next step focused on using these discoveries to produce photovoltaic (PV) materials.
  • the chalcopyrite CISSe was chosen as a next step due to its reduced complexity in comparison to CIGSSe and CZTSSe.
  • CISSe benefits from comparatively simplified crystallographic, stoichiometric, and defect chemistry properties due to the reduction in elemental constituents. Accordingly, the goal of this stage of the research was to transition from synthesizing simple binary metal-chalcogenides to more complicated PV materials.
  • CIS nanoparticles were synthesized in a manner similar to what was outlined in sections 1.3.1-1.3.3 of Example 1. Specifically, a batch of sulfur copolymer was synthesized using the methods outlined in section 1.3.1 (4.0 g). Next, copper (I) acetate (Cu(ac), 202 mg, 1.65 mmol 97.0%) and indium (III) acetate (In(ac), 482 mg, 1.65 mmol 99.9%) were added to a three-neck flask on top of the sulfur copolymer forming CIS nanoparticles. The flask was purged with vacuum and dry nitrogen several times. Next, the flask was heated to 200 °C and the metal precursors subsequently mixed with the liquid sulfur copolymer. The nanoparticles were allowed to grow for 30 min before the flask was cooled to room temperature. Next, the nanoparticles were removed from the sulfur copolymer using the methods detailed in section 1.3.3 of Example 1.
  • Isolated CIS nanoparticles were dispersed in formamide (200 mg/mL) and were sonicated for 30 min to ensure dispersion.
  • This nanoparticle ink was then pipetted onto a cleaned Mo coated SLG substrate in 7 ⁇ _, increments.
  • the ink was printed onto the substrate using a doctor-blade printing technique with a 125 ⁇ thick spacer and was then rapidly dried on a hot plate set at 300 °C in a fume hood for 10 s.
  • these printed thin films were annealed and selenized concurrently. Specifically, the films were placed in a graphite box and then were placed in a controlled atmosphere tube connected to a tube furnace.
  • the tube was purged with vacuum and argon several times to remove air and residual water vapor.
  • the furnace was heated to 500 °C while the sample remained outside of the furnace. Once the furnace reached a stabilized temperature, the sample was then placed into the furnace using a sealed pushrod. All samples used in this study were annealed for 20 minutes. For the selenium vapor reactions, approximately 400 mg of selenium was placed in the graphite box next to the samples (six selenium pellets).
  • FIGURE 15 shows the TEM images of the resulting nanoparticles. It is important to note that the metal precursors used were acetates, instead of acetylacetonates, as was used in the CdS synthesis. A precursor with a smaller counter ion was chosen in an effort to try to increase the reactivity of the precursors by choosing a smaller molecule. With a more reactive precursor, the nanoparticles will grow to a larger size, as is clearly seen in the TEM images in FIGURE 15. If larger, more crystalline nanoparticles can be grown in solution then this will facilitate the formation of a more crystallographically ordered thin- film material.
  • the nanoparticles were next printed onto Mo coated SLG substrates and analyzed with XRD (FIGURE 16), except without the annealing step. From the diffraction pattern, it is clear that the nanoparticles exhibit several different crystal structures. Although it is difficult to deconvolute these spectra, there are several peaks that are well defined and are consistent with the formation of Cu 2 S, CuInS 2 , and In 2 S 3 . Therefore, although several phases are present, some CIS formation does occur and the metals remain in the proper oxidation states (Cu 1+ and In 3+ ).
  • PL spectroscopy was conducted.
  • the PL spectra presented in FIGURE 20 is centred at approximately 1.0 eV (1240 nm) which is the theoretical bandgap value for a fully selenized CuInSe 2 material. This is extremely encouraging, since many printed PV materials exhibit a PL peak that is redshifted from the theoretical value due to the presence of defect states. However, the PL intensity of the peak is low, indicating that the photoluminescence quantum yield of the material is diminished.
  • the method suffers from some issues with the presence of copper-rich surface species that can quench PL and lead to recombination.
  • this issue can be fixed by synthesizing inks that are stoichiometrically indium rich at the outset.
  • sulfur copolymer is completely removed, it is likely that some surface defect passivation is lost. Therefore, it may be favourable to retain some amount of polymer to passivate these surface defects.
  • this Example constitutes a promising step towards making PV devices using these techniques.
  • Example 2 The work from the Example 2 showed that the disclosed methods can be effectively implemented to produce highly crystalline CISSe materials, with crystal growth properties that are extremely promising in comparison to what is seen for conventionally ligated nanoparticle inks. However, those methods still relied on a high- temperature (500 °C) annealing procedure and a concurrent selenium vapor-phase reaction. The ultimate goal of this work is to develop a method to make low-bandgap chalcogenide materials without high-temperature processing, expensive vapor-phase reaction procedures, or hydrazine (a highly toxic and explosive solvent), which has not been previously achieved.
  • hydrazine a highly toxic and explosive solvent
  • the organic monomer was refluxed until it completely reacted with the liquid radicals, at which point there was no longer any condensation within the condenser.
  • the ratio of S, Se, and a-methylstyrene yields a random terpolymer with a stoichiometry of 8:4: 1 for S:Se: a-methylstyrene as presented in FIGURE 2B.
  • CISSe nanoparticles were synthesized within a terpolymer matrix in a manner analogous to the techniques outlined in section 3.2.1.
  • the selenium sulfide terpolymer (4.0 g, 83.9 mmol chalcogen atoms) was placed in a three neck flask and copper (I) acetate (Cu(ac), 202 mg, 1.65 mmol 97.0%) and indium (III) acetate (In(ac), 482 mg, 1.65 mmol 99.9%) were added to a three-neck flask on top of the sulfur copolymer.
  • the mixture was heated to 215 °C with stirring and the metal precursors subsequently mixed with the liquid terpolymer.
  • the nanoparticles were allowed to grow for 30 min before the flask was cooled to room temperature. Next, the nanoparticles were removed from the sulfur copolymer using the methods detailed in section 1.3.3 of Example 1.
  • the CISSe nanoparticles were dispersed in anhydrous formamide (100 mg/mL) and were sonicated for 30 min to ensure dispersion.
  • the ink was then transferred to a controlled atmosphere glove box.
  • the ink was pipetted onto cleaned Mo coated SLG substrates in 100 ⁇ _, increments.
  • Printing was accomplished with a spin coater set at 2k rpm for 30 sec. Once the printing step was finished, the films were immediately placed on a hot plate and heated to 150 °C. This printing and drying cycle was repeated 10 times to produce a nanoparticle thin film. Next, the final films were placed on a hot plate and heated to 250 °C and were annealed for 1 hr.
  • FIGURE 21 shows some TEM images as well as a Fourier transform diffraction pattern for the synthesized CISSe nanoparticles.
  • FIGURES 21a, 21b, and 21c show that the CISSe nanoparticles exhibit a platelet morphology and range in size from 10 to 30 nm.
  • the particles remain suspended within some remaining chalcogen polymer. This can be attributed to the fact that some fraction of the selenium sulfide terpolymer is less soluble than the pure sulfur variant and is consequently more difficult to remove from the nanoparticles via the ultrasonication and centrifugation step.
  • the CISSe nanoparticles were then printed onto substrates and dried at 250 °C for
  • FIGURE 22 shows some representative SEM images of the resulting films as well as several elemental maps obtained via EDS spectroscopy.
  • FIGURES 22a and 22b show that the films consist of CISSe particles that remain suspended within the selenium sulfide terpolymer matrix, as opposed to the annealed films shown in the previous Example, where it is evident that all of the sulfur copolymer has been removed. This further confirms the evidence that the selenium sulfide terpolymer is less soluble and is more difficult to remove.
  • FIGURE 23 shows the XRD diffraction patterns for the films before and after annealing. Remarkably, these films show substantial crystal growth at this low temperature. This result is extremely encouraging and constitutes an important first step in the path towards making low-temperature, completely solution-processed chalcopyrite PV films.
  • the diffraction pattern is consistent with the formation of both CIS and CISe.
  • the annealed films were subsequently analysed with Raman spectroscopy (FIGURE 24).
  • the Raman spectrum shows a multitude of resonance modes that are consistent with the formation of CuInSe 2 , CuInSg, CuSe 2 , CuS 2 , In 2 Se 3 , In 2 S 3 , and chalcogen-chalcogen resonance modes.
  • FIGURE 25 shows the images and elemental maps for the films after the low-temperature annealing procedure.
  • the images and maps show that much of the terpolymer has evaporated.
  • the elemental maps show that there are some regions which are Cu rich while others are In rich, which agrees with the Raman spectra.
  • the images show that the particles have undergone some grain growth, with grains in the micron size range.
  • the films are also have good surface coverage in, which is encouraging for PV applications, however these films are in the range of 2-5 ⁇ in thickness, which is thicker than is needed for thin-film absorbers. This extra thickness eliminates the background signals associated with the molybdenum substrates, however future films will require optimization of the printing process.
  • Table 1 summarizes the stoichiometric date for these films from various EDS spectra.
  • Table 1 Stoichiometric ratios for pre-annealed and low-temperature annealed CISSe Films synthesized using the selenium sulfide terpolymer.
  • the Table 1 data indicate that some of the selenium sulfide terpolymer remains after this annealing procedure; however, much of it has evaporated, which is a very promising result.
  • the data also indicate that the films start out slightly copper rich and become even more copper rich after annealing.
  • the data show that as the films anneal, the selenium to sulfur ratio increases, indicating relative sulfur loss due to its higher vapor pressure.
  • the data also indicate that as the annealing process proceeds, the terpolymer vaporizes overall (although the rate of sulfur loss is faster than the rate of selenium loss), as indicated by the reduction in the overall chalcogen to metal ratios.
  • the films were examined with PL spectroscopy in order to gauge the quality of the material for PV applications (FIGURE 26).
  • the CCD system that was used has an abrupt reduction in sensitivity beginning at approximately 900 nm and extending into lower wavelengths, which means that the data beyond 900 nm should be considered qualitatively only and that the abrupt drop off seen in the data is likely due to this issue in part. Nevertheless, the spectrum is useful and promising for several reasons.
  • the broadness of the peak is due to the fact that a population of particles with a range of chalcogen stoichiometries that vary between that of CuInS 2 and CuInSe2 are illuminated simultaneously, thereby producing an amalgam of spectra that convolute to produce the broad peak observed in the data.
  • the data are also promising in that the PL signal is not completely quenched, as was seen in the small CIS particles that were annealed in the presence of Se vapor.
  • the selenium sulphide terpolymer may be useful as a mechanism to passivate surface defects when it is printed with the nanoparticles and is slowly volatilized as the films are annealed at this low temperature.
  • FIGURE 27 shows a schematic representation of the process.
  • the initial nanocomposite consists of CuInS x Se 2-x nanoparticles suspended within a selenium sulfide terpolymer matrix.
  • most of the polymer is removed via the ultrasonication and centrifugation process; however, some selenium rich polymer remains and coats the nanoparticles.
  • the nanoparticle ink is printed onto a substrate and is annealed at 250 °C.
  • chalcogen polymers that are highly reactive with metal precursors at low temperatures (100 °C) to form semiconducting materials, are miscible with metal precursor inks, are stable for months, are highly soluble, can be made with varying ratios of sulfur and selenium in the polymer backbone, and are readily amenable to large-scale printing methods such as blade coating.
  • these chalcogen polymers are made using a simple, scalable one-pot reaction with functionalized styrene monomers and liquid sulfur/selenium at 185 °C to 225 °C.
  • FIGURE 28 illustrates a representative copolymer having organic monomer units along with chalcogen sulfur and selenium units.
  • FIGURE 28 further includes photographs of chalcogen powder, representative chalcogen copolymer solids, and representative chalcogen copolymer solutions.
  • Elemental sulfur (1.0 g, 31.2 mmol S atoms) was placed in a 25 mL three neck flask.
  • the flask was connected to a temperature probe, a condenser, and connected to a Schlenk line.
  • the flask was placed on a heating mantle and was purged several times with vacuum and dry nitrogen.
  • the mixture was heated to 150 °C under dry nitrogen.
  • N,N-Dimethylvinylbenzylamine (DMVBA, mixture of isomers, 0.91 mL, 5.2 mmol, 97%) was injected.
  • the solution was heated to 185 °C and held for 10 mins to allow the organic monomer to completely react with the sulfur radicals.
  • ⁇ , ⁇ -Dimethylvinylbenzylamine (DMVBA, mixture of isomers, 2.2 mL, 12.6 mmol, 97%) was injected into the flask dropwise over the course of 5 min, to ensure that the mixture remained heated throughout the course of monomer addition (225 ⁇ 5 °C). The mixture was reacted for another 25 min once all of the monomer was injected, to allow the organic monomer to completely react with the selenium sulfide radicals. The flask was cooled immediately once the mixture became viscous, in order to limit the polymer growth and retain solubility.
  • DMVBA ⁇ , ⁇ -Dimethylvinylbenzylamine
  • the chalcogen polymer (500 mg) was placed in a 20 mL vial and combined with 20 mL of chloroform (CHC1 3 ). The vial was sealed and placed in an ultrasonicator for 60 min. This mixture was pipetted into two 20 mL Teflon centrifuge tubes and was centrifuged at 5 krpm for 10 min. The isolated polymer remained in solution while the unreacted chalcogen side-products dropped out of solution. The polymer was decanted from the centrifuge tubes and combined into a 20 mL vial. The CHCI 3 solvent was removed via rotovap and placed under high vacuum for 12 hr to ensure the removal of the solvent. 4.2.5 Polymer solution and ink preparation
  • the chalcogen polymers were dissolved in an organic solvent such as toluene at concentrations up to 1 mmol per mL and beyond this concentration to form printable, viscous gels. These polymer inks were then combined with various metal precursor salts dissolved in dimethylformamide (DMF) to produce a PV ink.
  • organic solvent such as toluene
  • DMF dimethylformamide
  • PV photovoltaics
  • perovskite materials are very efficient and can be printed using solution- processing methods, which provides a route for simple manufacturing; however, they have considerable stability issues.
  • Organic photovoltaics (OPVs) can also be solution- processed and are relatively cheap and simple to manufacture, but are comparatively unstable and inefficient.
  • Conventional silicon PV and thin-film metal -chalcogenide materials such as CdTe, the chalcopyrite material CuInS x Se 2- x (CISSe), the gallium alloy variant CuIn x Gai -x S y Se 2-y (CIGSSe), and the earth-abundant kesterite material Cu 2 ZnSnS x Se 4-x (CZTSSe) are stable and efficient, but are extremely complicated to manufacture, which causes the technology to remain expensive.
  • chalcogen polymers with a unique structure and have investigated how these novel chalcogen polymers can be used to fabricate metal-chalcogenide photovoltaic materials that are efficient, stable, and simple to manufacture via solution-processing.
  • chalcogen polymer solutions can be combined with metal precursor solutions to produce an ink that contains all of the necessary components to directly form a PV material without any additional reagents.
  • This ink can be printed onto a substrate (molybdenum coated glass) using simple, scalable printing techniques such as blade coating.
  • This amorphous polymer film can then be heated (115 °C) to form semiconducting nanoparticles.
  • the chalcogen atoms in the polymer backbone react with the metal precursors (for example: Cu + and In 3+ salts) to form a photovoltaic material (for example: CuInS x Se 2- x).
  • the reaction produces a semiconducting nanoparticle layer with some reaction side products and remaining monomers, which are subsequently washed away with an organic solvent, thereby yielding a bare nanoparticle film without problematic carbon impurities.
  • This nanoparticle film can then be annealed at a moderate temperature (300 °C) to produce a PV thin film.
  • FIGURE 29 illustrates a schematic of stepwise formation of a chalcogen- copolymer-containing photovoltaic thin film, including characterization of the film by optical microscopy, scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDS).
  • SEM scanning electron microscopy
  • EDS energy dispersive x-ray spectroscopy
  • SEM scanning electron microscopy
  • EDS energy dispersive x-ray spectroscopy
  • XRD x- ray diffraction
  • FIGURE 30F x- ray diffraction
  • FIGGURE 30G Raman spectroscopy
  • the photoluminescence (PL) data show that the material has the expected bandgap of 1.0 eV, which further confirms the formation of CuInSe 2 .
  • the narrow shape of the peak also indicates the formation of a high optoelectronic quality material, which is necessary for high performance devices.

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Abstract

L'invention concerne des copolymères comprenant une pluralité de motifs constitutionnels chalcogènes et une pluralité de motifs d'allongement de chaîne. Les copolymères sont donc des copolymères hybrides chalcogènes-organiques. Les propriétés des copolymères sont ajustables par choix du chalcogène, du motif monomère d'allongement de chaîne et des quantités relatives de chaque composant. L'invention concerne également des compositions qui comprennent les copolymères ; des surfaces qui comprennent les copolymères, des solutions (par exemple, des « encres ») qui comprennent les copolymères ; des procédés de formation des copolymères, des procédés de formation de films utilisant ou incorporant les copolymères, des nanoparticules qui comprennent les copolymères, et des dispositifs (par exemple, photovoltaïques) incorporant les copolymères.
PCT/US2017/037062 2016-06-10 2017-06-12 Copolymères de chalcogène WO2017214633A1 (fr)

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CN111987306A (zh) * 2020-06-09 2020-11-24 河南大学 一种钠离子电池负极材料
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CN111987306B (zh) * 2020-06-09 2021-06-11 河南大学 一种钠离子电池负极材料
CN113823747A (zh) * 2020-06-18 2021-12-21 Tcl科技集团股份有限公司 纳米材料及其制备方法和发光二极管
CN112951933A (zh) * 2021-02-24 2021-06-11 青岛科技大学 室温脉冲激光沉积法制备铜锌锡硫/硫化铋薄膜异质结

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