• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The present invention relates to a conducting film comprising a network of stacked 2-dimensional platelets, for example graphene platelets, and dopants encapsulated in inter-plate positions in the network of stacked 2-dimensional platelets. Thereby the dopants are to a high degree retained in the structure resulting in a thermally stable and highly conducting film. The dopants are retained within the network of stacked 2-dimensional platelets up to a temperature of at least 550 °C. The invention provides an industrially viable method of producing such films.
    公开号:SE1651087A1
    申请号:SE1651087
    申请日:2016-07-26
    公开日:2018-01-27
    发明作者:Majee Subimal；Zhang Zhibin
    申请人:Sht Smart High Tech Ab；
    IPC主号:
    专利说明:

    Thermally stable and highly conducting film comprising doped 2-dimensional platelets and method ofproducing such.
    Field of the lnventionThe present invention relates to a film comprising stacked doped 2-dimensional platelets and method ofproducing such. ln particular the invention relates to graphene based films doped with iodine.
    Background of the inventionTwo-dimensional materials such as graphene, hexagonal boron nitride, transition metal Di-chalcogenides(TMDCs) like MoSg, WSZ, MoSeg, WSeg, present a class of new materials for a variety of applications.Graphene, in particular, can be used as electrical and thermal conductive films. Applications of graphenefilms include, but are not limited to, electrical Wirings and interconnects in electronic devices and systems,surface coatings for heat dissipation and charge dissipation. A transparent conductive film (TCF) can beapplied to, but are not limited to, touch screens, liquid crystal displays (LCDs), organic photovoltaic cells(OPVs), organic light emitting diodes (OLEDs), smart Windows, sensors and lasers. Indium tin oxide (ITO)is the predominant material of TCFs. However, the use of ITO suffers from scarcity of indium, highprocessing costs and brittleness Which prevent their utilization in flexible electronic devices. A thin enoughgraphene film becomes optically transparent. The advantages of graphene TCF lies in its mechanicalrobustness and flexibility.
    Although graphene has potential to replace ITO used in TCFs and to replace metals used in coatings, it haslimited electrical conductivity, partly due to the limited carrier density in graphene. Currently, doping isrequired to increase the electrical conductivity of graphene thin films. Doping is also important to the other 2-dimensional materials to adjust their electrical and electronic properties. Among all the available dopingagents, such as, halogen dopants (Cl, Br, I and F), alkali metal based dopants (Li, Na, K, Cs) and other kindsof metals (Ca, etc.), acids (HCl, HNO3 and H2SO4) and some organic compounds; iodine is Widely employedas dopant for graphene and carbon nanotubes (CNTs). HoWeVer, the major draWback With the use of thesedopants is the poor thermal stability. As an example, When iodine is used as dopant, it easily detaches andescapes from the host at a temperature as low as at 100 °C or under Vacuum condition. This creates reliabilityproblems in many applications, for example if Joule heating starts to play a role. Therefore, doped graphenefilms of highly thermal stability are required. The same requirement is posed for the other 2-dimensionalmaterials.
    Disclosed in Doping efiïciency of single and randomly stacked bilayer graphene by iodine adsorption,HoKWon Kim et al, Applied Physics Letters 105, 011605 (2014) (and references therein) is a method of dopinga single layer graphene film With iodine. The doping is performed by dipping a single layer graphene film ona substrate into a statured aqueous solution of 12 resulting in a charge transfer doping. The reference teachesthat other structures such as nanotubes can be coated/doped in a similar Way [Scientific Reports, 1, 83 (2011)].
    HoWeVer it is concluded that the structure is not stable even at temperatures as low as around 150 °C.
    Stability ofgraphene doping with M0O3 and I2, Lorenzo D'Arsie et al, Applied Physics Letters 105, 103103(2014) describes a 12 doped structure comprising randomly stacked double layer graphene. It is discussed thatthe oVerlapping bilayered structure prevents eVaporation and the doping remains effective up to a temperatureof around 200 °C.
    Summary of the inventionRecent developments in graphene film technology have addressed the issue of limited carrier density ingraphene, primarily by different kind of doping. Although improved, thermal and long term stability are stillmajor drawbacks. Complexity and cost of the suggested doping methods are also a hinder for scaling up theprocesses to an industrial scale.
    The object of the invention is to provide a production method and a highly conducting film that overcomes thedrawbacks of prior art techniques. This is achieved by the methods as defined in claim 9 and 14, and thethermally stable and highly conducting film the material as defined in claim 1.
    The present invention describes films consisting of randomly stacked 2-dimensional platelets most of whichare doped. 2-dimensional platelets may include, but are not limited to, graphene, hexagonal boron nitride, andtransition metal Di-chalcogenides (TMDCs) such as MoSg, WSZ, MoSeg, and WSeg. Dopants may compriseiodine and bromine. Materials used as dopant sources may also include, but are not limited to, metals (Li, Na,K, Cs, Ca, etc., MoOg and acids (HCl, HNOg and H2SO4). The dopants can be present on surface of plateletsin the form of atoms, ions, molecules, and compounds. The dopant can also be clustered to form nanoparticles.The dopants function as electron donor or acceptor which increases carrier density and as a result increases theelectrical conductivity of the films.
    According to one aspect of the invention, the conducting film is provided on a substrate. The film comprises anetwork of stacked 2-dimensional platelets and dopants encapsulated in inter-plate positions in the network ofthe stacked 2-dimensional platelets. The dopants may be present in different forms or a mixture of differentforms comprising particles, preferably nano- and/or microparticles, atoms, ions, molecules and compounds. Inthis structure the dopants are to a high degree retained in the structure, resulting in a thermally stable and highlyconducting film. The dopants are retained within the network of stacked 2-dimensional platelets up to atemperature of at least 300 °C, preferably up to at least 400 °C and even more preferably up to at least 500 °C.
    According to another aspect of the invention, the 2-dimensional platelets of the conducting film are randomlystacked and closely packed. The randomly stacked 2-dimensional platelets form a network of electricalpathway in the film. The maj ority of the platelets are coated in both sides with dopants.
    According to yet another aspect of the invention, the 2-dimensional platelets of the conducting film aregraphene platelets. The network of stacked graphene platelets may be arranged to form a transparentconductive films (TCF) which is an important element in many applications such as touch screens and smartwindows.
    According to yet another aspect of the invention, iodine and/or bromide is used as a dopant and iodine and/orbromide is present as nanoparticles in inter-plate positions in the network of stacked 2-dimensional platelets.
    According to the method of the invention a film of doped 2D-platelet films can be formed by a deposition anddoping method. In this procedure, the first step is to form films of randomly stacked 2-dimensional platelets.This is followed by doping process when dopants diffuse through the networks of voids present in the films ofrandomly stacked 2-dimensional platelets and fill the networks of voids. The method comprises the steps of:-substrate treatment, comprising washing and drying of the substrate;-2-dimensional platelets coating, comprising that a dispersion of platelets is deposited on the substrate,forn1ing a coated substrate comprising a network of platelets on the substrate;-post-deposition treatment, comprising drying and annealing the coated substrate;-dopant coating, wherein dopant particles are provided to the network of platelets.-post treatment, comprising drying of the solvent from the dopant solution.
    According to another aspect of the invention, the dopant coating is provided by immersing the coatedsubstrate in a aqueous iodine solution.
    According to yet another aspect of the invention, the film material of doped 2-dimensional -platelet films canbe formed by a doping and deposition method. In this procedure, the 2-dimensional platelets are coated withdopants in solution. This is followed by a deposition of the doped platelets. According to this aspect of theinvention the steps of 2-dimensional platelets coating and dopant coating is combined so that a previouslyprepared dispersion of platelets and dopants is deposited on the substrate, forn1ing a coated substratecomprising a network of doped platelets on the substrate.
    According to a further aspect of the invention, the step of 2-dimensional platelets coating or the combined stepof 2-dimensional platelets coating and dopant coating is performed by inkjet printing.
    Thanks to the present invention the well-known problems of un-doped film materials (low carrier density) ordoped film materials (low thermal stability) may be overcome. In the film material according to the invention,the escape of dopants can be efficiently prevented which makes the doping stable up to at least 500 °C evenunder high vacuum condition.
    Afforded by the present invention is a method that is cost effective and well suited for industrial scale-up.
    One advantage of the inventions is that transparent and highly conducting films can be provided at reasonablecosts and with and expected long lifetime, which is sought for in many applications.
    A further advantage is that the conducting films can be produced by a process with relatively few steps andwhich may utilize well established techniques such as ink-jet printingDescription of drawingsA more complete understanding of the above mentioned and other features and advantages of the presentinvention Will be apparent from the following detailed description of preferred embodiments in conjunctionWith the appended drawings, Wherein:Figure 1 is a schematic illustration of the film according to the invention;Figure 2 is an AFM image in top-view of a doped graphene platelet film according to the invention.
    Figure 3 is a graph of the change of sheet resistance of a doped graphene platelet film according to theinvention;Figure 4 is a floWchart over the method of producing a doped film according to the invention;Figure 5 is a floWchart over one embodiment of the method of producing a doped film according to theinvention.
    Detailed descriptionA conducting film 100 according to the present invention is schematically illustrated in Fig. 1. The conductingfilm 100 is typically provided on a substrate 110, Which can be silicon, glass, polymeric substrates such aspolyimide (PI), Polyethylene terephthalate (PET) and Polyethylene naphthalate (PEN), cellulose substrate likepaper board, and silicone based rubbers. The conducting film 100 comprises of a network of stacked 2-dimensional platelets 120. The platelets are typically and preferably stacked in a random manner. The platelets120 comprise one or a combination of the materials: graphene, hexagonal boron nitride, and transition metalDi-chalcogenides (TMDCs) such as MoSg, WSg, MoSeg, and WSeg. Most of the platelets are coated Withdopants. Dopants may comprise iodine and bromine. Materials used as dopant sources may also include, butare not limited to, metals (Li, Na, K, Cs, Ca, etc.), MoOg, and acids (HCl, HNOg and H2SO4). The dopants canbe present on the surface of platelets in the form of atoms, ions, molecules, and compounds 130. The dopantcan also be clustered to form particles, typically and preferably micro- or nanoparticles. In the film accordingto the invention, the platelets 120 are stacked and packed closely in a way that the dopants are encapsulated ininter-plate positions 140. Thereby the dopants are prevented from leaving the structure even at elevatedtemperature and under vacuum condition. Preferably the platelets 120 are in a size range from 100 nm to 1000nm and single or few atomic layers. The size of the platelets 120 can also comprise the range up to hundredsmicrometer.
    The structure of the film according to the invention, with dopants 130 encapsulated at inter-plate positions 140in the network of stacked platelets 120, provides that the dopants to a high degree are retained within thenetwork up to a temperature of at least 300 °C, preferably up to at least 400 °C and even more preferably up toat least 550 °C.
    According to one embodiment of the invention the thermally stable and highly conducting film 100 comprisesgraphene platelets as the 2-dimensional platelets 120. The graphene platelets 120 may for example have beenprovided by means of inkjet printing on a substrates 110. The platelets 120 is in a size range from 100 to 1000nm with a typical average size of 300 nm. The dopant comprises iodine and/or bromide in a form that comprisesparticles, preferably and typically nanoparticles 130 wherein at least a portion is arranged in inter-platepositions 140. Iodine/bromide may also be present as smaller molecules and ions. Suitable graphene plateletsare possible to produce with known methods or alternatively are commercially available from for examplesuppliers such as Sigma-Aldrich. Methods for providing iodine dopants will be described below.
    According to one embodiment of the invention the network of stacked graphene platelets (120) forms atransparent conductive films (TCF). TCF are a particularly interesting product that can be included in a longrange of products such as touch screens, liquid crystal displays (LCDs), organic photovoltaic cells (OPVs),organic light emitting diodes (OLEDs), smart windows, sensors and lasers.
    A film 100 according to the present invention is depicted in Fig. 2, which is an AFM image in top-view showingthe presence of halogen dopant in the form of iodine present on the top surface of graphene in a film consistingof randomly stacked and closely packed graphene platelets. The film has before doping an electricalconductivity at 4 >< 104 S/m. The doped film 100 according to the embodiment of the invention show a notableenhancement in DC conductivity from 4 >< 104 S/m up to ~105 S/m (sheet resistance, RS ~ 80 Q/U coupled Withan optical transmittance, T ~70% at 550 nm Wavelength). The stability assessment of the doped graphene TCFsby means of electrical characterization, as illustrated in Fig. 3, showing a graph of the change of sheetresistance of the film consisting of randomly stacked graphene platelets Which are doped With halogen as theVariation of annealing temperature in Vacuum. The Vacuum is ~10'6 mbar during annealing. The stability isadditionally confirmed by Raman spectroscopy showing significant thermal stability up to 550 °C and timedependent ambient stability for ~3 months. X-ray photoelectron spectrometer (XPS) on a film that has beenannealed at 500 °C confirms the presence of iodine in the film.
    The method according to the inVention of producing a film comprising of stacked doped 2-dimensionalplatelets Will be described With reference to the floWchart of Fig. 4. The method comprises the steps:410: Substrate treatment, Which comprises Washing and drying of the substrate, for example a glasssubstrate.420: 2-dimensional platelets coating; In this step a dispersion of graphene platelets is deposited onsubstrate; The methods include, but are not limited to, dip-coating, spraying, spin-coating and printing e. g.,ink-jet printing, screen printing, and graVure printing.430: Post-deposition treatment, Which comprises drying and annealing at temperature e. g., from 200to 260 °C, to remove solVents and dispersion agents from the deposited platelets and substrate440: Dopant coating, Which can be conducted by immersing the samples in dopant solutions or bydeposition of dopant solution on top of the film.450: Post treatment, Which refers to drying of the solVent from the dopant solution.
    According to one embodiment of the inVention the step 420 of 2-dimensional platelets coating, is performedby means of inkjet printing.
    According to one embodiment of the inVention the step 440 of dopant coating, is performed by means ofimmersing the films in saturated aqueous iodine solution With a concentration in the range 0.01 to 0.5 mM. Analternative method, representing on embodiment of the method according to the inVention utilizes acombination of the 2-dimensional platelets coating and the Dopant coating. The embodiment of the methodWill be described With reference to the flowchart of Fig. 5, and comprises the steps:510: Substrate treatment, Which comprises Washing and drying of the substrate, for example a glasssubstrate.520: 2-dimensional platelets and dopants mixing. This step is implemented by mixing of 2-dimensional platelets and dopant in dispersion. The dispersion comprises graphene platelets and dopants inliquid. Graphene platelets are dispersed With aid of stabilizers.530: Deposition coating, Which implements the deposition of 2-dimensional platelets With dopantfrom dispersion on substrate. The methods of coat include, but are not limited to, dip-coating, spraying, spin-coating and printing (e. g., ink-j et printing, screen printing, and gravure printing)540: Post-deposition treatment, Which comprises drying and annealing at temperature e. g., from 200to 260 °C, to remove solvents from the deposited platelets and substrate to remove solvents and dispersionagents from the deposited platelets and substrate.
    In the above embodiments of the method graphene is used as a non-limiting example. Alternatively to grapheneplatelets, the dispersion can comprise the other types of 2-dimensional material such as hexagonal boronnitride, and transition metal Di-chalcogenides (TMDCs) such as MoSg, WSQ, MoSeg, and WSeg platelets.Solvents used to disperse platelets include, but are not limited to, ethanol, N, N-dimethylformamide; N-Methyl-2-pyrrolidone; Cyclohexanone and Water. Different types of stabilizing agents that are used indispersion includes, but not limited to, surfactants (e.g., Sodium dodecyl sulfate, Sodiumdodecylbenzenesulfonate, Sodium Cholate); cellulose (e.g., Nanofiber cellulose, Ethyl Cellulose;(Hydroxypropyl) methyl cellulose). The platelets are deposited from the dispersion. Preferably the platelets120 are in a size range from 100 nm to 1000 nm and single or few atomic layers. The size of the platelets 120can also comprise the range up to hundreds micrometer.
    Materials used as dopant sources in the embodiments of the method according to the invention include, but arenot limited to iodine and bron1ine, metals (Li, Na, K, Cs, Ca, etc., MoOg and acids (HCl, HNOg and H2SO4).
    The possibility to produce doped graphene platelet films that is stable up to at least 500 °C, Which representsa stability 5 times higher than the state of the art, opens up for new applications for graphene based technology.In particular this can extend the application of films of doped 2-dimensional platelets Which requires largeWorking temperature range. For example, When a TCF made of the present inVention is used as electrode inorganic photoVoltaic cells (OPV), it can increase the reliability and extend the lifetime since a constant sunlightirradiation generates heat and thus increase the temperature in the device. In principle, an enhanced electricalconductiVity is usually accompanied by an increase of thermal conductiVity for a metal. When a conductivegraphene film is used for heat and charge dissipation, this requires a film of high thermal stability. When aconductiVe graphene film is used as electrical Wiring and interconnects, high stability and reliability to jouleheating are important.
    The film according to the inVention may be utilized in a Wide range of applications, including, but not limitedto electrodes in touch screens, transparent conducting electrodes in liquid crystal displays (LCDs), organicphotovoltaic cells (OPVs), organic light emitting diodes (OLEDs), photochromatic (smart) Windows, printedantennas, electromagnetic radiation shielding, anti-corrosion coatings, electrodes in thin film transistors,sensors and lasers.
    权利要求:
    Claims (16)
    [1] Claims:
    [2] A conducting film (100) provided on a substrate (110), the film (100) comprising a network ofstacked 2-dimensional platelets (120), characterized in that the film (100) comprises dopants (130) encapsulated in inter-plate positions(140) in the network of stacked 2-dimensional platelets (120), thereby the dopants are to a high degree retained in the structure.
    [3] The conducting film (100) according to claim 1, wherein the dopants are retained within the networkof stacked 2-dimensional platelets (120) up to a temperature of at least 300 °C, preferably up to at least 400 °C and even more preferably up to at least 500 °C.
    [4] The conducting film (100) according to claim 2, wherein the network of stacked 2-dimensionalplatelets (120) comprises one or a combination of the materials: graphene, hexagonal boron nitride, and transition metal Di-chalcogenides, such as MoSg, WSg, MoSeg, and WSeg.
    [5] The conducting film (100) according to claims 2 or 3, wherein the dopants comprises one of or a combination of bromide and iodine.
    [6] The conducting film (100) according to claim 4, wherein at least a portion of the dopants are present in the inter-plate positions (140) in the form of particles, preferably microparticles or nanoparticles.
    [7] The conducting film (100) according to any of claims 2 to 5, wherein platelets are graphene platelets.
    [8] The conducting film (100) according to claim 6, wherein the network of stacked graphene platelets (120) forms a transparent conductiVe films.
    [9] The conducting film (100) according to claim 5, wherein at least a portion of the dopants are nanoparticles (130) comprising iodine. 11
    [10] 10.
    [11] 11.
    [12] 12.
    [13] 13.
    [14] 14.
    [15] 15. The conducting film (100) according to any of claims 2 to 8, Wherein the network of stacked 2- dimensional platelets (120) comprises randomly stacked 2-dimensional platelets (120). A method of producing a thermally stable and conducting film (100), the method comprising thesteps of: -substrate treatment, comprising washing and drying of a substrate; -2-dimensional platelets coating, comprising that a dispersion of platelets is deposited on thesubstrate, forn1ing a coated substrate comprising a network of platelets on the substrate;-post-deposition treatment, comprising drying and annealing the coated substrate; -dopant coating, wherein dopant particles are provided to the network of platelets. -post treatment, comprising drying of the solvent from the dopant solution. The method according to claim 10, Wherein the step of dopant coating comprises immersing the coated substrate in at least one dopant solution. The method according to claim 11, Wherein the step of dopant coating comprises immersing the coated substrate in a aqueous iodine solution. The method according to claim 10, Wherein the step of dopant coating comprises deposition of at least one dopant solution on top of the coated substrate. The method according to any of claims 9 to 13, Wherein the step of 2-dimensional platelets coating is performed by inkjet printing. A method of producing a thermally stable and highly conducting film (100), the method comprisingthe steps of: -substrate treatment, comprising washing and drying of a substrate; -2-dimensional platelets and dopants mixing, comprising mixing of 2-dimensional platelets anddopant to form a dispersion; -2-dimensional platelets coating and dopants coating, comprising that the dispersion of platelets and dopants is deposited on the substrate, forn1ing a coated substrate comprising a network of doped 12 platelets on the substrate; -post-deposition treatment, comprising drying and annealing the coated substrate.
    [16] 16. The method according to any of claims 9 to 13, Wherein the step of 2-dimensiona1 platelets and dopants coating is performed by inkj et printing. 13
    类似技术:
    公开号 | 公开日 | 专利标题
    US20180297840A1|2018-10-18|Metal nanowire networks and transparent conductive material
    Gomathi et al.2017|Large‐area, flexible broadband photodetector based on ZnS–MoS2 hybrid on paper substrate
    Zhong et al.2016|Continuous patterning of copper nanowire-based transparent conducting electrodes for use in flexible electronic applications
    Aliprandi et al.2017|Hybrid copper‐nanowire–reduced‐graphene‐oxide coatings: a “green solution” toward highly transparent, highly conductive, and flexible electrodes for | electronics
    US20090169819A1|2009-07-02|Nanostructure Films
    Coskun et al.2013|Optimization of silver nanowire networks for polymer light emitting diode electrodes
    KR101611421B1|2016-04-26|Nanostructure-film lcd devices
    Layani et al.2009|Transparent conductive coatings by printing coffee ring arrays obtained at room temperature
    Wang et al.2011|Flexible graphene-based electroluminescent devices
    CN102834936B|2015-05-20|Nanowire-based transparent conductors and methods of patterning same
    Hu et al.2010|Flexible organic light-emitting diodes with transparent carbon nanotube electrodes: problems and solutions
    CN102324462B|2015-07-01|Nanowire-based transparent conductors and applications thereof
    KR20110036543A|2011-04-07|Improved cnt/topcoat processes for making a transplant conductor
    Chien et al.2010|A solution processed top emission OLED with transparent carbon nanotube electrodes
    US20080317982A1|2008-12-25|Compliant and nonplanar nanostructure films
    Xian et al.2017|A Practical ITO Replacement Strategy: Sputtering‐Free Processing of a Metallic Nanonetwork
    Ding et al.2014|Fabrication and Characterization of Organic Single Crystal‐Based Light‐Emitting Devices with Improved Contact Between the Metallic Electrodes and Crystal
    Aleksandrova2016|Specifics and challenges to flexible organic light-emitting devices
    JP6465795B2|2019-02-06|Method for improving the electrical and / or optical performance of transparent conductor materials based on silver nanowires
    Wang et al.2017|Roll-to-roll slot die production of 300 mm large area silver nanowire mesh films for flexible transparent electrodes
    KR101296809B1|2013-08-14|Conductivity enhanced carbon nanotube films by graphene oxide nanosheets
    Kong et al.2020|Significant enhancement of out-coupling efficiency for yarn-based organic light-emitting devices with an organic scattering layer
    SE1651087A1|2018-01-27|Thermally stable and highly conducting film comprising doped2-dimensional platelets and method of producing such
    Li et al.2017|Highly-flexible, ultra-thin, and transparent single-layer graphene/silver composite electrodes for organic light emitting diodes
    Sim et al.2021|Highly flexible Ag nanowire network covered by a graphene oxide nanosheet for high-performance flexible electronics and anti-bacterial applications
    同族专利:
    公开号 | 公开日
    SE540866C2|2018-12-04|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    SE1651087A|SE540866C2|2016-07-26|2016-07-26|Thermally stable and highly conducting film comprising doped2-dimensional platelets and method of producing such|SE1651087A| SE540866C2|2016-07-26|2016-07-26|Thermally stable and highly conducting film comprising doped2-dimensional platelets and method of producing such|
    [返回顶部]