WO2012158125A1 - Procédé d'amélioration de la conductivité électrique d'un film de pedot:pss - Google Patents

Procédé d'amélioration de la conductivité électrique d'un film de pedot:pss Download PDF

Info

Publication number
WO2012158125A1
WO2012158125A1 PCT/SG2012/000175 SG2012000175W WO2012158125A1 WO 2012158125 A1 WO2012158125 A1 WO 2012158125A1 SG 2012000175 W SG2012000175 W SG 2012000175W WO 2012158125 A1 WO2012158125 A1 WO 2012158125A1
Authority
WO
WIPO (PCT)
Prior art keywords
pedotpss
acid
films
film
pedot
Prior art date
Application number
PCT/SG2012/000175
Other languages
English (en)
Other versions
WO2012158125A8 (fr
Inventor
Jianyong Ouyang
Yilie XIA
Original Assignee
National University Of Singapore
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by National University Of Singapore filed Critical National University Of Singapore
Publication of WO2012158125A1 publication Critical patent/WO2012158125A1/fr
Publication of WO2012158125A8 publication Critical patent/WO2012158125A8/fr

Links

Classifications

    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass
    • H10K71/40—Thermal treatment, e.g. annealing in the presence of a solvent vapour
    • H10K71/441—Thermal treatment, e.g. annealing in the presence of a solvent vapour in the presence of solvent vapors, e.g. solvent vapour annealing
    • 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
    • H10K85/113—Heteroaromatic compounds comprising sulfur or selene, e.g. polythiophene
    • H10K85/1135—Polyethylene dioxythiophene [PEDOT]; Derivatives thereof
    • 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
    • H10K30/80—Constructional details
    • H10K30/81—Electrodes
    • 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

Definitions

  • the present invention relates to a method of improving electrical conductivity of PEDOTPSS.
  • the present invention also relates to a PEDOT:PSS film prepared according to the method.
  • Optoelectronic devices such as liquid crystal displays (LCDs), light-emitting diodes (LEDs), solar cells, touch panel displays, and detectors, have been attracting considerable attention, due to their strong application in various areas.
  • the market for optoelectronic devices is huge and is still rapidly expanding.
  • At least one electrode of an optoelectronic device is required to be transparent in order to emit or harvest light.
  • ITO indium tin oxide
  • ITO indium tin oxide
  • ITO indium tin oxide
  • ITO indium tin oxide
  • PEDOTPSS poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)
  • a PEDOTPSS film has high transparency in the visible range, high mechanical flexibility, and excellent thermal stability.
  • PEDOTPSS suffers a problem of low conductivity.
  • An as- prepared PEDOTPSS film fabricated from its aqueous solution usually has a conductivity below 1 S/cm, which is remarkably lower than that of ITO. Hence, it is important to significantly enhance the conductivity of PEDOTPSS films.
  • PEDOTPSS ethylene glycol and dimethyl sulfoxide
  • polar organic solvents such as ethylene glycol and dimethyl sulfoxide (DMSO) or the addition of an ionic liquid, an anionic surfactant, or dimethyl sulphate into the PEDOTPSS aqueous solution.
  • methods comprising treating PEDOT:PSS films with a polar organic compound, a certain salt, a zwitterion, or cosolvent.
  • the highest conductivity is about 700- 900 S/cm.
  • the present invention seeks to address at least one of the problems in the prior art, and provides a method for preparing poly(3,4- ethylenedioxythiophene):poly(styrenesulfonate) (PEDOTPSS) with improved electrical conductivity.
  • PEDOTPSS poly(3,4- ethylenedioxythiophene):poly(styrenesulfonate)
  • the heat treating may comprise treating the PEDOTPSS film with a fluorine-containing compound or an acid at a suitable temperature.
  • the temperature may be about 120-180°C.
  • the temperature is about 140-160°C.
  • any suitable fluorine-containing compound may be used in the heat treating.
  • the fluorine-containing compound may be an organic fluorine-containing compound.
  • the fluorine-containing compound may be an amphiphilic fluorine-containing compound or a geminal diol.
  • the amphiphilic fluorine-containing compound may be, but not limited to, hexafluoroacetone hydrate, hexafluoroisopropanol, 2,2,2-trifluoroethanol, heptafluorobutyric acid, trifluoroacetic acid, 2,2,3,3,3-pentafluoropropionic acid, 2,2,3,3,3-pentafluoropropanol, trifluoromethanesulfonic acid, or a combination thereof.
  • the geminal diol may be, but not limited to, cyclohexanehexone octahydrate, hexafluoroacetone trihydrate, formaldehyde, acetaldehyde, acetone, perfluorobenzophenone, or a combination thereof.
  • the acid may be any acid which has a pK a which is less than or equal to -2.8.
  • the acid may be, but not limited to, sulphurous acid, sulphuric acid, oxalic acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, phosphoric acid, nitric acid, methanesulfuric acid, fluorosulfuric acid, fluoroantimonic acid, hydrochlorous acid, chlorous acid, chloric acid, perchloric acid, fluoroboric acid, hexafluorophoric acid, chromic acid, boric acid, or a combination thereof.
  • the substrate may be any suitable substrate.
  • the substrate may be a transparent substrate and/or a flexible substrate.
  • the substrate may be a plastic or glass substrate.
  • the method may further comprise applying the PEDOTPSS film on the surface of a substrate prior to the providing the substrate.
  • the substrate may be as described above.
  • the applying may be by any suitable method.
  • the applying may be by, but not limited to, spin coating, spray coating, roller coating, chemical deposition, drop casting, ink-jet printing, rotogravure printing, doctor blading, wire bar coating, electrochemical deposition, or a combination thereof.
  • the applying is by spin coating.
  • the method may further comprise drying the heat treated PEDOT:PSS film.
  • the method may further comprise repeating the heat treating the PEDOTPSS film for a second or subsequent time after the drying of the heat treated PEDOTPSS film.
  • the present invention provides a poly(3,4- ethylenedioxythiophene):poly(styrenesulfonate) (PEDOTPSS) film obtained from the method according to the first aspect of this invention.
  • PEDOTPSS poly(3,4- ethylenedioxythiophene):poly(styrenesulfonate)
  • an article of manufacture comprising the PEDOTPSS film obtained from the method according to the first aspect of the invention.
  • the article of manufacture may be any suitable article.
  • the article of manufacture may be an optoelectronic device or a flexible electronic device.
  • the article of manufacture may be, but not limited to, a light-emitting diode (LED), a flat panel display, a solar cell, a flexible display, a touch panel, a transparent electrode, an electrochromic display, a smart window, or a detector.
  • LED light-emitting diode
  • the article of manufacture may be, but not limited to, a light-emitting diode (LED), a flat panel display, a solar cell, a flexible display, a touch panel, a transparent electrode, an electrochromic display, a smart window, or a detector.
  • Figure 1 is a flow chart showing the general method of improving the electrical conductivity of PEDOTPSS according to the present invention
  • Figure 2 shows the dependence of conductivity of PEDOT:PSS on the treatment temperature with H 2 S0 solution
  • Figure 3 shows the transmittance of a 1 10 nm thick PEDOTPSS film treated with hexafluoroacetone (HFA);
  • Figure 4 shows the conductivity of PEDOTPSS films after one treatment with H 2 S0 4 solutions of different concentrations at 160°C;
  • Figure 5 shows the conductivity of PEDOTPSS films after one treatment with 1 M H 2 S0 solution at different temperatures
  • Figure 6 shows the temperature dependence of the normalized resistance of untreated and H 2 S0 4 treated PEDOTPSS films
  • Figure 7 shows the analysis of resistance-temperature relationship of the H 2 S0 treated PEDOTPSS film with the VRH model
  • Figure 8 shows the spectra of PEDOTPSS films - (a) transmittance spectra of PEDOTPSS films. The thickness was 24, 66, 109 nm for the H 2 S0 4 treated PEDOTPSS film formed by spin coating the PEDOTPSS aqueous solution once, thrice and five times, respectively, (b) XPS spectra of untreated and H 2 S0 4 treated PEDOTPSS films, (c) FTIR spectra of untreated and H 2 S0 4 treated PEDOTPSS film and H 2 S0 4 . The films were treated with 1 M H 2 S0 4 for three times in (a), (b) and (c);
  • Figure 9 shows the AFM height images of (a) untreated PEDOTPSS film and (b) PEDOTPSS film treated with 1 M H 2 S0 4 for three times.
  • the unit for the AFM images is ⁇ ;
  • Figure 10 shows (a) the device architecture of a polymer solar cell with a H 2 S0 4 treated PEDOTPSS film as the transparent anode, (b) chemical structure of P3HT and PCBM, and (c) J-V characteristics of polymer PVs with ITO and H 2 S0 4 treated PEDOTPSS film as the anode under AM 1 .5G illumination (100 mW/cm 2 );
  • Figure 1 1 shows the transmittance spectra of PEDOTPSS films treated with HFA, HFP and 12.2 M formaldehyde solution;
  • Figure 12 shows (a) the temperature dependence of the normalized resistance of untreated and treated PEDOTPSS films and (b) analysis of resistance-temperature relationship of the untreated and treated PEDOT:PSS film with the VRH model.
  • the resistances are normalized to that of the corresponding PEDOTPSS films at 1 10 K;
  • Figure 13 shows the UV absorption spectra of PEDOTPSS films before and after treatments with different solutions
  • Figure 14 shows the S 2p XPS of untreated and treated PEDOTPSS films
  • Figure 15 shows the AFM images of (a) untreated, (b) HFA treated, (c) HFP treated, (d) 36.5% formaldehyde treated, and (e) 2,2,2-trifluoroethanol treated PEDOTPSS films.
  • the unit for the AFM images is ⁇ ;
  • Figure 16 shows the conductivities of PEDOTPSS films after treatment with HFA solutions of various concentrations at 140°C;
  • Figure 17 shows the conductivities of PEDOTPSS films after treatment with HFA.3H 2 0 at various temperatures
  • Figure 18 shows the transmittance spectra of PEDOTPSS film
  • Figure 19 shows (a) the temperature dependence of the normalized resistance of untreated and HFA treated PEDOTPSS films and (b) analysis of resistance- temperature relationship of the untreated and HFA treated PEDOTPSS film with the VRH model.
  • the resistances are normalized to that of the corresponding PEDOTPSS films at 1 10 K;
  • Figure 20 shows the UV absorption spectra of PEDOTPSS films before and after treatment with HFA
  • Figure 21 shows the S 2p XPS of untreated and HFA treated PEDOTPSS films
  • Figure 22 shows the AFM images of (a) untreated and (b) HFA treated PEDOTPSS films.
  • the unit is ⁇ ;
  • Figure 23 shows cyclic voltammograms of PEDOTPSS films untreated, treated with HFA.3H 2 0 and an aqueous solution of 15 wt% HFA.3H 2 0 in 0.1 M NaCI solution;
  • Figure 24 shows J-V characteristics of polymer PVs with ITO and HFA treated PEDOTPSS electrodes under 100 mW/cm 2 AM 1 .5G illumination.
  • the exemplary embodiments aim to provide a simple method of improving the electrical conductivity of PEDOTPSS.
  • the method of the present invention significantly enhances the electrical conductivity of PEDOTPSS.
  • the electrical conductivity of PEDOTPSS achieved by using the method of the present invention is comparable to the electrical conductivity of ITO on polyethylene terephthalate (PET) and close to the electrical conductivity of ITO on glass. Accordingly, the PEDOTPSS with enhanced electrical conductivity obtained from the method of the present invention may be used as a replacement for ITO as transparent electrodes in optoelectronic devices.
  • the method of the present invention is a cheap and scalable method, ensuring that the cost of providing PEDOT:PSS with enhanced electrical conductivity remains affordable.
  • a method of improving the electrical conductivity of PEDOTPSS comprising:
  • the method 100 for improving the electrical conductivity of PEDOTPSS may generally comprise the steps as shown in Figure 1. Each of these steps will now be described in more detail.
  • Step 102 comprises applying poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOTPSS) solution on a surface of a substrate to form a PEDOTPSS film 1 18 on the surface of the substrate.
  • PEDOTPSS generally has the structure as shown in Scheme 1 below.
  • PEDOTPSS can be dispersed in water and some organic solvents.
  • PEDOTPSS can processing techniques. Such methods may include coating and printing.
  • PEDOTPSS films have high transparency in the visible range, high mechanical flexibility and good thermal stability. It has been understood that PEDOTPSS has a core/shell structure in water and in PEDOTPSS films. The shell is rich of insulating PSS, while the core is rich of conductive PEDOT.
  • the substrate onto which the PEDOTPSS solution is applied may be any suitable substrate for the purposes of the present invention.
  • the substrate may be a transparent substrate and/or a flexible substrate.
  • the substrate may be a plastic or glass substrate.
  • the plastic substrate may be a substrate containing polypropylene (PP), polycarbonate (PC), polyimide (PI), polyethersulfone (PES), polyethylene terephthalate (PET), polymethylmethacrylate (PMMA), polyethylene (PE), polyethylenenaphatalene (PEN), polyvinylalcohol (PVA), polyvinylchloride (PVC), cyclic olefin copolymer (COC), styrene polymer, or a mixture or copolymer thereof.
  • PP polypropylene
  • PC polycarbonate
  • PI polyimide
  • PES polyethersulfone
  • PET polyethylene terephthalate
  • PMMA polymethylmethacrylate
  • PE polyethylene
  • PE polyethylenen
  • the step 102 of applying may be carried out under conditions suitable for the purposes of the present invention and may comprise any suitable method of applying the PEDOTPSS solution on the surface of the substrate.
  • the step 102 of applying may be by any suitable deposition method.
  • the step 102 of applying may comprise chemical deposition or physical deposition of the PEDOTPSS on the substrate surface.
  • the step 102 of applying may comprise wet chemistry, spin coating, spray coating, roller coating, chemical solution deposition, drop casting, electrohydrodynamic deposition, ink-jet printing, rotogravure printing, doctor blading, wire bar coating, electrochemical deposition, spin on glass (SOG) or a combination thereof, of the PEDOTPSS solution on the substrate surface.
  • the step 102 of applying comprises spin coating the PEDOTPSS on the surface of the substrate.
  • the step 102 of applying may also comprise chemical vapour deposition, plasma-enhanced chemical vapour deposition, thermal evaporator, electron beam evaporator, sputtering, pulsed laser deposition, cathodic arc deposition, physical vapour deposition, and molecular beam epitaxy.
  • the substrate may be pre-cleaned prior to the step 102 of applying the PEDOT:PSS solution on the substrate surface. Any suitable pre-cleaning method may be used prior to the step 102.
  • the PEDOT:PSS film 1 18 formed on the substrate surface may have any thickness suitable for the purposes of the present invention.
  • the PEDOTPSS film 1 18 may be a thin PEDOTPSS film.
  • the PEDOTPSS film 1 18 may have a thickness between 3 nm to 1 mm.
  • the PEDOTPSS film 1 18 may have a thickness of less than 500 nm, 400 nm, 300 nm, 200 nm, 100 nm, 50 nm, 25 nm, 20 nm, 15 nm, 10 nm, or 5 nm.
  • the PEDOTPSS film 118 may be a single layer or multiple layers, and wherein each layer of the PEDOTPSS film 1 18 may be of the same or different thickness from the other layer.
  • Step 104 comprises drying the PEDOTPSS film 1 18 obtained from step 102.
  • the step 104 of drying may be carried out under any suitable conditions.
  • the step 104 of drying may be carried out at a suitable temperature for a suitable period of time.
  • the step 104 of drying may be carried out at about 00-150°C.
  • the step 104 of drying may be carried out for about 1 -20 minutes.
  • the PEDOTPSS film 1 18 after the step 104 of drying may then be subjected to a step 106 of heat treating the PEDOTPSS film 1 18. It should be noted that if at the step 106 a substrate with a pre-applied PEDOTPSS film on its surface is used, the steps 102 and 104 may not be required for the method 100.
  • the step 106 of heat treating the PEDOTPSS film 1 18 may comprise treating the PEDOTPSS film 1 18 with a fluorine-containing compound or an acid at a suitable temperature.
  • a heat treated PEDOTPSS film 120 with improved electrical conductivity compared to the PEDOTPSS film 18 is obtained.
  • the temperature may be about 120-180°C.
  • the temperature may be about 125-175°C, 130-165°C, 140-160°C, 145-150°C. Even more in particular, the temperature may be about 140-160°C.
  • the fluorine-containing compound may be any suitable compound which comprises at least one fluorine atom for the purposes of the present invention.
  • the fluorine-containing compound may be an organic fluorine-containing compound.
  • the fluorine-containing compound may be a compound which hydrolyzes into a geminal diol with water.
  • an amphiphilic fluorine-containing compound is defined as a chemical compound which comprises at least one fluorine atom and which possess both hydrophilic and hydrophobic properties.
  • the fluorine-containing compound may be, but not limited to, hexafluoroacetone hydrate (HFA), hexafluoroisopropanol, 2,2,2-trifluoroethanol, heptafluorobutyric acid, trifluoroacetic acid, 2,2,3,3, 3-pentafluoropropionic acid, 2,2,3,3,3-pentafluoropropanol, trifluoromethanesulfonic acid, or a combination thereof.
  • HFA hexafluoroacetone hydrate
  • hexafluoroisopropanol 2,2,2-trifluoroethanol
  • heptafluorobutyric acid trifluoroacetic acid
  • 2,2,3,3, 3-pentafluoropropionic acid 2,2,3,3,3-pentafluoropropan
  • a geminal diol is defined as a chemical compound which has at least two hydroxyl groups which are bonded to the same atom.
  • Geminal diols are usually generated through hydrolysis of ketones or aldehydes. The equilibrium constant for the conversion of a ketone or aldehyde into a geminal diol depends on the molecular structure. Any suitable geminal diol may be used for the purposes of the present invention.
  • the geminal diol may be, but not limited to, cyclohexanehexone octahydrate, hexafluoroacetone trihydrate, formaldehyde, acetaldehyde, acetone, perfluorobenzophenone, or a combination thereof.
  • the fluorine-containing compound may be hexafluoroacetone (HFA).
  • HFA hydrolyzes into 1 ,1 ,1 ,3,3,3-hexafluoropropane-2,2-diol (HFP20H) with water. This is shown in Scheme 2 below.
  • HFP20H is a geminal diol with two -OH groups connected to the middle carbon atom and is highly amphiphilic arising from the hydrophobic -CF 3 and hydrophilic -OH groups.
  • the formation of the geminal diol is due to the two electron-withdrawing -CF 3 groups.
  • the equilibrium constant of the hydrolysis is 10 6 at room temperature.
  • HFA.3H 2 Treatment of PEDOTPSS with a geminal diol enhances the conductivity of PEDOTPSS even more significantly than normal polyols with only one -OH group connected to a carbon atom.
  • the amphiphilic groups can preferentially interact with the hydrophobic PEDOT and hydrophilic PSS chains of PEDOTPSS, and these interactions can give rise to conductivity enhancement of PEDOTPSS.
  • the PEDOTPSS film has a core/shell structure in which the shell is rich of insulating PSS, while the core is rich of conductive PEDOT.
  • HFA HFA-induced PSSH reduction reduces the thickness of the less conductive shell and benefits the charge transport across the PEDOT chains.
  • the energy barrier for the interchain and inter-domain charge hopping is lowered, giving rise to significant conductivity enhancement. While the above explanation specifically refers to HFA, it would be understood by a person skilled in the art that the same applies to any fluorine-containing compound used for the step 106 of heat treating the PEDOTPSS film 1 18.
  • the acid may be an acid which has a pK a which is less than or equal to -2.8.
  • the acid may be, but not limited to, sulphurous acid, sulphuric acid, oxalic acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, phosphoric acid, nitric acid, methanesulfuric acid, fluorosulfuric acid, fluoroantimonic acid, hydrochlorous acid, chlorous acid, chloric acid, perchloric acid, fluoroboric acid, hexafluorophoric acid, chromic acid, boric acid, or a combination thereof.
  • the acid may be sulphuric acid (H 2 S0 4 ).
  • H 2 S0 4 dissociates into H + and HS0 4 " ions.
  • This dissociation has a pK a of -6.4 in water.
  • the pK a value of H 2 S0 4 is higher than the pK a value of PSSH (PSSH -» PSS " + H + ).
  • H + from H 2 S0 4 will associate with PSS " that exists as the counter anions of positively charged PEDOT in the untreated PEDOTPSS film 1 18 by following the scheme H + + PSS " -> PSSH.
  • the total reaction can be written as: This results in the replacement of some PSS " with HS0 4 " as the counter anions of PEDOT.
  • the PSSH chains are neutral and do not have any Coulombic interaction with PEDOT, so that phase separation occurs between the hydrophilic PSSH and hydrophobic PEDOT chains.
  • the replacement of PSS ' with HS0 4 " results in the conformational change of conjugated PEDOT chains.
  • PEDOT has a coil conformation as the result of the coiled PSS " conformation and the Coulombic interactions between PSS " and positively charged PEDOT in the untreated PEDOTPSS film 1 18.
  • the coil conformation causes the localization of the positive charges on the PEDOT chains.
  • the disappearance of the Coulombic attractions between PEDOT and PSSH can thus induce conformational change of PEDOT from the coil to extended-coil or linear structure.
  • the removal of PSSH leads to the reduction of the energy barrier width for the interchain and inter-domain charge hopping, whereas the conformational change of PEDOT makes the positive charges on PEDOT more delocalized. Both effects contribute to the conductivity enhancement of PEDOTPSS. While the above explanation specifically refers to H 2 S0 4 , it would be understood by a person skilled in the art that the same applies to any other acid used for the step 06 of heat treating the PEDOTPSS film 1 18.
  • the method 100 may further comprise a step 108 of drying the heat treated PEDOTPSS film 120.
  • the step 108 of drying may or may not be carried out under similar conditions to the step 104 of drying the PEDOTPSS film 1 18.
  • the step 108 of drying the heat treated PEDOTPSS film 120 may be carried out at about 100-150°C.
  • the step 108 of drying may be carried out for about 1 -20 minutes.
  • the step 108 may be carried out at about 160°C for about 5 minutes.
  • the heat treated PEDOTPSS film 120 is then subjected to a step 1 10 of cooling the heat treated PEDOTPSS film 120.
  • the step 10 of cooling may be carried out under any suitable conditions.
  • the step 1 10 of cooling may be carried out until the heat treated PEDOTPSS film 120 reaches a suitable temperature.
  • the step 1 10 of cooling may be carried out until the heat treated PEDOTPSS film cools down to room temperature or about 25°C.
  • the heat treated PEDOTPSS film 120 may then be rinsed according to step 1 12.
  • the step 1 12 of rinsing may be with any suitable solvent.
  • the heat treated PEDOTPSS film 120 may be rinsed with deionised water.
  • the step 1 12 of rinsing may be repeated more than one time.
  • step 1 14 of drying may be similar to the steps 104 and 108, as described above.
  • the step 106 of heat treating the PEDOT:PSS film 120 may be repeated at least once. This may result in a PEDOT:PSS film 122 which has an electrical conductivity which is even higher than the electrical conductivity of the PEDOT:PSS film 120. Steps 108 to 1 14 may also be repeated following the repetition of the step 106.
  • the steps 102 to 106 may be repeated to obtain a thicker PEDOT:PSS film 122 which has an electrical conductivity which is even higher than the electrical conductivity of the PEDOT:PSS film 120.
  • Steps 108 to 1 14 may also be repeated following the repetition of the steps 102 to 106.
  • the prepared PEDOT:PSS films 120 and 122 have desirable properties. As mentioned above, the electrical conductivity of the PEDOT:PSS films 120 and 122 are enhanced compared to the untreated PEDOTPSS film 1 18. In fact, the electrical conductivity of the PEDOTPSS films 120 and 122 are enhanced by an order of more than 10 3 . Further, despite the heat treatment, the PEDOT:PSS films 120 and 122 are able to maintain the transparency of the PEDOT:PSS and have transmittance which is higher than 90% in the wavelength below 550 nm. The PEDOT:PSS films 120 and 122 are also thermally stable. In this way, the PEDOTPSS films 120 and 122 may be used in optoelectronic devices in view of the high conductivity and transparency.
  • the method 100 is a simple and cost-effective method. Further, the method 100 is a scalable method, thus allowing the method 100 to be scaled up to an industrial scale.
  • the method 100 may be suitable for fabricating thin films of PEDOTPSS with high conductivity, high transparency and high stability on flexible substrates.
  • the method 100 results in the penetration of the fluorine-containing compound or acid into PEDOTPSS, thereby resulting in the improvement of the electrical conductivity of PEDOT:PSS.
  • the penetration of the fluorine-containing compound or acid causes the PEDOT chains to separate from the PSS chains, which gives rise to a reduction in the Coulombic attraction between PEDOT and PSS.
  • a phase segregation occurs between the hydrophobic PEDOT and hydrophilic PSS chains.
  • a poly(3,4- ethylenedioxythiophene):poly(styrenesulfonate) (PEDOTPSS) film obtained from or obtainable by the method described above.
  • the PEDOTPSS film may have desirable properties such as an improved electrical conductivity suitable.
  • the electrical conductivity may be comparable to that of indium tin oxide (ITO) films.
  • the PEDOTPSS film may be as described in relation to the heat treated PEDOTPSS films 120 and 122.
  • the present invention further provides an article of manufacture comprising the PEDOTPSS film 120 or 122.
  • the article of manufacture may be any suitable article of manufacture which requires a PEDOTPSS film with high electrical conductivity.
  • the article of manufacture may be any suitable article of manufacture in which ITO films are currently used.
  • the article of manufacture may comprise optoelectronic devices or a flexible electronic device.
  • the flexible electronic device may comprise flexible optoelectronic devices.
  • the article of manufacture may be, but not limited to, a light-emitting diode (LED), a flat panel display, a solar cell, a flexible display, a touch panel, a transparent electrode, an electrochromic display, a smart window, or a detector.
  • LED light-emitting diode
  • the article of manufacture may be, but not limited to, a light-emitting diode (LED), a flat panel display, a solar cell, a flexible display, a touch panel, a transparent electrode, an electrochromic display, a smart window
  • PEDOTPSS aqueous solution (CleviosTM PH1000) was obtained from H.C. Starck. The concentration of PEDOTPSS was 1 .3% by weight, and the weight ratio of PSS to PEDOT was 2.5 in solution.
  • PEDOTPSS films were prepared by spin coating the PEDOTPSS aqueous solution on eleven 1 .3 x 1.3 cm 2 glass substrates, which were pre-cleaned successively with detergent (Sigma-Aldrich), de-ionized (Dl) water, acetone (Sigma-Aldrich) and isopropanol (IPA) (Sigma-Aldrich). The PEDOTPSS films were dried at 1 10°C on a hot plate for 30 min. The treatment was performed by dropping 100 ⁇ _ solvent or solution as indicated in Table 1 on each of the eleven PEDOTPSS films on a hot plate at 140°C. The films were then dried for about 5 minutes.
  • the conductivity of each of the PEDOTPSS films were measured by the van der Pauw four-point probe technique with a source meter (Keithley instruments, Series 2400).
  • the electrical contacts were made by pressing indium on the four corners of each PEDOTPSS film on the glass substrate.
  • the UV-Vis-NIR absorption spectra of the polymer films were taken with a Varian Cary 5000 UV-Vis-NIR spectrometer.
  • the thicknesses of the polymer films were determined with an Alpha 500 step profiler.
  • the conductivity increased to 1 160 S/cm and 1500 S/cm for the PEDOTPSS films treated with hexafluoroacetone at 140°C and with 0.5 M sulohuric acid at 140°C. respectively. These conductivities were significantly higher than that of the PEDOTPSS films treated with ethylene glycol or DMSO. When a PEDOT:PSS film was treated with ethylene glycol at 160°C, the conductivity was only 700 S/cm, and it was 600 S/cm by adding 5% DMSO into the PEDOTPSS aqueous solution. Table 1 also lists the conductivities of PEDOTPSS films treated with other fluorine-containing compounds and acids.
  • Table 1 Conductivities of PEDOTPSS films after treatment with different solvents at different temperatures The improvement in the conductivity enhancement was dependent on the temperature during the treatment.
  • Figure 2 shows the conductivities of PEDOT:PSS films treated with H 2 S0 4 at different temperatures. The conductivity was more . than 1 ,200 S/cm when the temperature during the treatment with the H 2 S0 4 was more than 120°C.
  • Figure 2 shows that the optimal temperature or treatment with H 2 S0 4 was about 140°C.
  • the conductivity of the PEDOT:PSS films was further improved by multiple heat treatments with the solvent/solution. For example, when a PEDOT:PSS film treated with hexafluoroacetone was subjected to a repeat of the heat treatment with hexafluoroacetone again, the conductivity of the PEDOT:PSS film was 1650 S/cm.
  • FIG. 3 shows the transmittance spectrum of a 1 10 nm thick PEDOT:PSS film treated with hexafluoroacetone in the visible range. As seen from the figure, the transmittance is about 90.6% at 550 nm. The transmittance is higher than 90% at a wavelength below 550 nm, and decreases slightly but still higher than 85% at a wavelength over 550 nm.
  • PEDOT:PSS aqueous solution (Clevios PH1000) from H. C. Starck was used.
  • concentration of PEDOTPSS was 1 .3% by weight, and the weight ratio of PSS to PEDOT was 2.5 in solution. All other chemicals were obtained from Sigma-Aldrich. All the materials were used without further purification.
  • PEDOTPSS films were prepared by spin coating the PEDOT:PSS aqueous solution on 1 .3 x 1 .3 cm 2 glass or PET substrates, which were pre-cleaned successively with detergent, de-ionized (Dl) water, acetone and isopropanol (IPA).
  • the PEDOTPSS films were dried at 120°C on a hot plate for 15 minutes.
  • the H 2 S0 4 treatment was performed by dropping 100 ⁇ _ H 2 S0 4 solution on a PEDOTPSS film on a hot plate at 160°C. The films were dried for about 5 minutes.
  • PEDOTPSS films were dried at 160°C for about 5 minutes again. Some PEDOTPSS films were treated with a H 2 S0 solution multiple times. Thick PEDOT.PSS films were prepared by spin coating the PEDOTPSS aqueous solution multiple times. The PEDOTPSS films were dried after each spin coating and then treated with H 2 S0 4 .
  • the conductivities of the PEDOT.PSS films were measured by the van der Pauw four- point probe technique with a Keithley 2400 source/meter.
  • the electrical contacts were made by pressing indium on the four corners of each PEDOT SS film on glass substrate.
  • the temperature dependences of the resistivity of the untreated and H 2 S0 4 treated PEDOTPSS films were tested using a Janis Research VPF-475 dewar with liquid nitrogen as coolant and a Conductus LTC- 1 temperature controller.
  • the UV-Vis- NIR absorption spectra of the PEDOTPSS films were taken with a Varian Cary 5000 UV-Vis-NIR spectrometer, and the AFM images of the PEDOTPSS films were obtained using a Veeco NanoScope IV Multi-Mode AFM with the tapping mode.
  • the X- ray photoelectron spectroscopy (XPS) spectra were collected with an Axis Ultra DLD X- ray photoelectron spectrometer equipped with an Al K a X-ray source (1486.6 eV).
  • the thicknesses of the PEDOTPSS films were determined with an Alpha 500 step profiler.
  • the ac impedance spectra were obtained using an SI 1260 impedance analyzer.
  • the highly conductive PEDOTPSS films on glass were used as the anode of polymer solar cells. It was coated with a 50 nm thick PEDOTPSS film (Clevios Al 4083 by H. C. Starck).
  • the active layer was formed by spin coating a 1 ,2-dichlorobenzene solution consisting of 20 mg/mL P3HT (poly(3-hexylthiophene-2,5-diyl)) and 20 mg/mL PCBM ([6, 6]-phenyl-C 6 i -butyric acid methyl ester) at 800 rpm for 1 minute in a glove box filled with nitrogen. It was dried at room temperature for 3 hours and had a thickness of about 220 nm.
  • P3HT poly(3-hexylthiophene-2,5-diyl)
  • PCBM [6, 6]-phenyl-C 6 i -butyric acid methyl ester
  • the devices were completed by thermally depositing a 20 nm-thick Ca layer and subsequently a 200 nm-thick Al layer in a vacuum of 10 ⁇ 6 mbar. Each polymer solar cell had an active area of 0.09 cm 2 .
  • the polymer solar cells were encapsulated with a UV-curable epoxy and glass sheets in the glove box. They were then taken out for electrical testing.
  • the photovoltaic performance of the devices was measured with a computer-programmed Keithley 2400 source/meter.
  • the light source was a Newport's Oriel class A solar simulator, which simulated the AM1 .5G sunlight (100 mW/cm 2 ) and was certified to the JIS C 8912 standard.
  • the conductivity increased to more than 1000 and 2000 S/cm after treatment with 0.05 M and 1 M H 2 S0 4 , respectively.
  • the maximum conductivity reached 2400 S/cm when the H 2 S0 4 concentration was 1 .5 M.
  • the conductivity enhancement depended on the temperature during the treatment, as shown in Figure 5.
  • the optimal treating temperature was 160°C.
  • the effect of the temperature during the H 2 S0 4 treatment on the conductivity of the PEDOTPSS film may be considered to be related to the thermal properties of the PEDOT: PSS films.
  • the conductivity of the PEDOTPSS films was further enhanced by multiple treatments with H 2 SO 4 as presented in table 2 below.
  • a conductivity of 3065 S/cm was observed after the PEDOTPSS film was treated with 1 M H 2 S0 4 at 160°C for three times. This conductivity is comparable to that of ITO, and is significantly higher than that demonstrated by other methods in the prior art.
  • the resistance of the PEDOTPSS films before and after the H 2 S0 4 treatment was investigated from 313 K down to 1 10 K. The results obtained are shown in Figure 6.
  • the resistance of the H 2 S0 treated PEDOTPSS film decreased with the elevating temperature. It became almost constant at temperature above 230 K. It can therefore be concluded that the H 2 S0 4 treated PEDOTPSS film behaves almost like a metal or semimetal.
  • the log R vs T "1 2 has a linear relationship at the low temperature range below 230 K, and the T 0 value estimated from this linear relationship is 29 K. It deviates from the linear relationship at T>230 K.
  • the temperature dependence of the resistance of the H 2 S0 4 treated PEDOTPSS film is saliently different from that of the untreated PEDOTPSS film.
  • the latter has a linear log R vs T "1/2 relationship in the whole temperature range from 1 10 to 300 K, and the estimated T 0 value is 1901 K.
  • the H 2 S0 4 treatment can significantly reduce the energy barrier for the interchain and inter-domain charge hopping.
  • the thickness of PEDOTPSS films is reduced after the treatment with H 2 S0 4 as shown in Table 2.
  • the sheet resistance of the PEDOTPSS film is 136 ⁇ sq " after the treatment with 1 M H 2 S0 4 for three times.
  • Thick PEDOTPSS films with a low sheet resistance can be obtained by spin coating the PH1000 solution for multiple times.
  • Treatment with 1 M H 2 S0 4 was carried out on each PEDOTPSS layer.
  • the conductivity of the H 2 S0 4 treated multiple-layer PEDOTPSS film was slightly lower still higher than 2500 S/cm.
  • the transmittance of the 66 nm-thick PEDOTPSS film, whic has a sheet resistance of 67 ⁇ sq "1 , is 87% at 550 nm.
  • the transmittance is higher than 90% in the wavelength below 500 nm, and decreases a little but still higher than 80% at the wavelength above 550 nm.
  • the transmittance of the 109 nm-thick PEDOTPSS film, which has a sheet resistance of 39 ⁇ sq "1 is more than 80% at 550 nm.
  • the thickness of the ITO layer on ITO/PET is about 100 nm, quite close of the thickness of the thickest PEDOTPSS film in Figure 8(a).
  • the optical absorption coefficient of the H 2 S0 4 treated PEDOTPSS films is slightly higher than ITO.
  • the PEDOTPSS films before and after the H 2 S0 4 treatment were further characterized by X-ray photoelectron spectroscopy (XPS), UV absorption spectroscopy, FTIR spectroscopy and atomic force microscopy (AFM).
  • XPS X-ray photoelectron spectroscopy
  • UV absorption spectroscopy UV absorption spectroscopy
  • FTIR spectroscopy atomic force microscopy
  • AFM atomic force microscopy
  • the two XPS bands between 166 and 172 eV are the S 2p band of the sulfur atoms in PSS
  • the two XPS bands between 162 and 166 eV are the S 2p band of the sulfur atoms in PEDOT.
  • the S 2p XPS intensity ratio of PEDOT to PSS saliently increased after the H 2 S0 treatment. This indicated the removal of some PSSH chains from the PEDOTPSS film.
  • the XPS spectra indicate that the C/S molar ratio changed from 6.4 to 4.2 after the H 2 S0 4 treatment.
  • the change in the C/S molar ratio is consistent with the removal of PSSH from PEDOTPSS.
  • This conclusion is confirmed by the UV absorption spectra.
  • the two absorption bands in the UV range originate from the aromatic ring of PSS. Their intensities remarkably drop after the H 2 S0 4 treatment.
  • the PEDOTPSS films were also characterized by the FTIR spectroscopy ( Figure 8(c)).
  • the FTIR bands near 600 cm "1 are the S-0 stretching modes of the sulfate ions. These bands are absent in the FTIR spectrum of the untreated PEDOTPSS film, while they appear for the H 2 S0 treated PEDOTPSS film. Therefore, it can be concluded that some sulfate ions remain in the PEDOTPSS film after the H 2 S0 4 treatment even after The surface morphology of the PEDOT:PSS films changed after the H 2 S0 4 treatment, as seen in Figure 9.
  • the untreated PEDOT:PSS film was quite smooth with a RMS roughness of 1 .63 nm.
  • the RMS roughness increased to 2.95 nm after the H 2 S0 treatment.
  • entangled wires with a diameter of tens of nanometers could be observed on the H 2 S0 4 treated PEDOT:PSS films.
  • the AFM images suggest the conformational change of the polymer chains during the H 2 S0 4 treatment, which may be related to the change in the energy barrier of charge hopping as observed by the temperature dependence of the resistances.
  • the H 2 S0 4 treated PEDOTPSS films were used to replace ITO as the transparent electrode of polymer solar cells.
  • the device architecture and the chemical structure of P3HT and PCBM are shown in Figure 10(a) and Figure 10(b), respectively.
  • the H 2 S0 4 treated PEDOTPSS film had a thickness of 70 nm.
  • the current density (J )-voltage (V) curves of these solar are presented in Figure 10(c).
  • the device with the H 2 S0 4 treated PEDOTPSS film anode exhibited high photovoltaic performance: J sc of 9.29 mA/cm 2 , V oc of 0.59 V, FF of 0.65, and PCE of 3.56%.
  • the photovoltaic performance was comparable to that of the control devices using ITO anode, as can be seen from the results in Table 3.
  • PEDOTPSS films were prepared in the same manner as described in Example 2. Once the PEDOTPSS films were obtained, treatment was performed by dropping 100 ⁇ _ geminal diol or fluorine-containing compound or an aqueous solution of the same on a PEDOTPSS film on a hot plate at 140°C. The films were dried for about 5 minutes. They were cooled down to room temperature, and then were rinsed with deionized water. Finally, the treated PEDOTPSS films were dried at 140°C for about 5 minutes again.
  • the conductivity of the untreated PEDOTPSS film was found to be 0.3 S/cm.
  • Tables 4 and 5 provide the conductivities of the PEDOTPSS films after the treatment with the different compounds.
  • PEDOTPSS films were treated with a neat compound or a maximum concentration solution.
  • the numbers in the parentheses indicate the concentrations for the aqueous solutions used for the treatment
  • PEDOTPSS films were treated with a neat compound or a maximum concentration solution.
  • the numbers in the parentheses indicate the concentrations for the aqueous solutions used for the treatment
  • PEDOT:PSS film treated with cyclohexanehexone was also investigated. Only its geminal dioi structure, dodecahydroxycyclohexane, exists in water. Cyclohexanehexone is a solid at room temperature, and it has limited solubility in water. The conductivity of PEDOTPSS film enhanced to 349 S/cm after a treatment with 0.1 M cyclohexanehexone aqueous solution.
  • FIG. 1 1 shows the transmittance spectra of PEDOT:PSS films treated with HFA, HFP and formaldehyde. more than 90% in the visible range from 400 to 700 nm.
  • the HFA-treated PEDOTPSS films, as well as the HFP and formaldehyde treated PEDOTPSS films had comparable transmittance and surface resistance to ITO on plastic.
  • Figure 12b shows the analysis of the temperature dependences of the resistances with the one-dimensional variable range hopping (VRH) model, which has been described in Example 2 above.
  • the untreated PEDOTPSS film has a linear logR vs T "1 2 in the whole temperature range from 1 10 to 310 K, and the estimated T 0 value from this linear relationship is 1901 K.
  • the logR vs T "1 2 relations of the HFA and HFP treated PEDOTPSS films had a linear relationship only at the low temperature range below 200 K, and the T 0 value estimated from the linear relationships are 99 and 127 K, respectively.
  • the T 0 value of PEDOTPSS film treated with formaldehyde at T ⁇ 200 K is 194 K.
  • T 0 values in the low temperature range were consistent with the conductivities of the PEDOTPSS films at room temperature, which were 0.3, 1 64, 1022, and 862 S/cm for the untreated, HFA, HFP, and formaldehyde treated PEDOTPSS films, respectively.
  • T 0 decreased with the increasing conductivity.
  • the treatment with a geminal diol or an amphiphilic fluorine-containing compound lowers the energy barrier for the interchain and inter-domain charge hopping.
  • the logR vs T "1/2 curves of the PEDOTPSS films treated with HFA, HFP and formaldehyde show that the polymer films experience a phase transition at around 230 K.
  • the T 0 value of PEDOTPSS films treated with formaldehyde decreased to 54 K at the temperature range from 230 to 310 K.
  • the resistances of the PEDOTPSS films treated with HFA and HFP were almost insensitive to temperature at the temperature range of more than 230 K.
  • the phase transition at around 230 K for the PEDOTPSS films treated with HFA and HFP was an insulator-to-metal Dhase transition.
  • X-ray diffraction band for untreated PEDOTPSS films and PEDOTPSS films treated with HFA, HFP and formaldehyde was not observed.
  • the mechanism for the conductivity enhancements of PEDOT:PSS by treatment with geminal diols and amphiphilic fluorine-containing compounds was studied by various chemical and physical characterizations.
  • the UV absorption spectra of PEDOTPSS films are shown in Figure 13.
  • the intensities of the two absorption bands hardly changed after a treatment with 2,2,2-trifluoroethanol. This indicates that the treatment with 2,2,2-trifluoroethanol did not give rise to remarkable change in the composition of PEDOTPSS.
  • the changes in the UV absorption spectra of PEDOTPSS films after the treatment with different compounds are consistent with the effects of these compounds on the conductivity of the PEDOTPSS films.
  • the reduction of PSSH from the PEDOTPSS films after treatment was confirmed by the XPS spectra of the PEDOTPSS films ( Figure 14).
  • the two XPS bands with binding energies between 166 and 172 eV are the S 2p bands of the sulfur atoms in PSS, whereas the two XPS bands with binding energies between 162 and 166 eV are the S 2p bands of the sulfur atoms in PEDOT.
  • the S 2p XPS intensity ratio of PEDOT to PSS increased after the HFA and HFP treatment, while it only slightly changed after the treatment with 2,2,2-trifluoroethanol.
  • the surface morphology of the PEDOT:PSS films also changed after the treatment with geminal diols and fluorine-containing compounds as seen from the AFM results shown in Figure 15.
  • the rms roughness was 1 .63 nm, 1 .68 nm, 1 .44 nm, and 2.27 nm for the untreated, HFA, HFP, and formaldehyde treated PEDOTPSS films.
  • the apparent rms roughness increased to 4.88 nm for the PEDOTPSS film treated with 2,2,2- trifluoroethanol. This was mainly due to the appearance of pores in the 2,2,2- trifluoroethanol-treated PEDOTPSS film.
  • a close-up look on the AFM image showed changes in the morphology of the PEDOTPSS films after the treatment. Fiber structures were observed on the PEDOTPSS films treated with HFA, HFP and formaldehyde, while they were absent for the untreated and 2,2,2-trifluoroethanol- treated PEDOTPSS films.
  • the change in the AFM images indicates phase segregation of PSSH chains from PEDOTPSS films after the treatment. It also indicates the conformational change of the PEDOT chains during the treatment.
  • PEDOTPSS films were prepared in the same manner as described in Example 2. Once the PEDOTPSS films were obtained, treatment was performed by dropping 100 ⁇ _ pure HFA.3H 2 0 (Sigma-Aldrich) or an aqueous solution of the same on a PEDOTPSS film on a hot plate at 140°C. The films were dried for about 5 minutes. They were cooled down to room temperature, and then were rinsed with deionized water. Finally, the treated PEDOTPSS films were dried at 140°C for about 5 minutes again. Some PEDOTPSS files were treated multiple times. Thick PEDOTPSS films were prepared by spin coating the PEDOTPSS aqueous solution multiple times. The PEDOTPSS films were dried after each spin coating, and an HFA treatment was carried out after each spin coating.
  • the conductivities, temperature dependences of the resistivities, UV-Vis-NIR absorption spectra, AFM images, XPS spectra and thicknesses of the PEDOTPSS films were measured in the same manner as described in Example 2 above. Cyclic voltammetric (CV) measurements were carried out with a ECO CHEMIE AUTOLAB PGSTAT 302N + FRA2 system in 0.1 M NaCI solution with a Au disc coated with a PEDOTPSS film as the working electrode.
  • the PEDOTPSS films for the CVs were prepared by dropping PEDOTPSS aqueous solution on a Au disc with a diameter of 2 mm and subsequently drying at 120°C.
  • a Pt wire and Ag/AgCI (3 M NaCI) were used as the counter and reference electrodes, respectively.
  • the scan rate was 50 mV/s.
  • the X-ray diffractions (XRD) of the thin films were analyzed using a Bruker D8 Advance X- ray diffractometer equipped with Cu Kai radiation (40 kV, 40 mA).
  • PEDOTPSS films on glass were used as the anode of polymer solar cells (PSCs).
  • 50 nm thick PEDOTPSS film (Clevios Al 4083 by H. C. Starck) was spin coated on a HFA-treated PEDOTPSS film as a buffer layer.
  • the active layer was formed by spin coating a 1 ,2-dichlorobenzene solution consisting of 18 mg/mL P3HT and 18 mg/mL PCBM at 500 rpm for 1 minute in a glove box filled with nitrogen. It was dried at room temperature for 3 hours and had a thickness of about 200 nm.
  • the devices were completed by thermally depositing a 40 nm-thick Ca layer and subsequently a 200 nm-thick Al layer in a vacuum of 10 ⁇ 6 mbar.
  • Each PSC had an active area of 0.1 1 cm 2 .
  • the P3HT and PCBM were used as the donor and acceptor in the active layer.
  • the polymer solar cells were encapsulated with a UV-curable epoxy and glass sheets in the glove box. They were then taken out for electrical testing.
  • the photovoltaic performance of the devices was measured with a computer-programmed Keithley 2400 source/meter.
  • the light source was a Newport's Oriel class A solar simulator, which simulated the AM1 .5G sunlight (100 mW/cm 2 ) and was certified to the JIS C 8912 Results and discussion
  • FIG 16 presents the conductivities of PEDOTPSS films after treatment with aqueous solutions of different HFA concentrations.
  • the as-prepared PEDOTPSS films had a conductivity of 0.3 S/cm.
  • the conductivity was significantly enhanced after the treatment, and the conductivity increased with the increasing HFA concentration.
  • the highest conductivity of 1 164 S/cm was observed for the treatment ith pure HFA.3H 2 0.
  • This conductivity is saliently higher than that of PEDOTPSS treated with ethylene glycol or DMSO once.
  • the highest conductivity is only 735 S/cm for the PEDOTPSS films treated with ethylene glycol, and it is 680 ⁇ 50 S/cm by adding 5% DMSO into the PH1000 aqueous solution as reported in the prior art.
  • PEDOTPSS films were further enhanced through the treatment with HFA multiple times. It reached 1325 S/cm after treatment with HFA.3H20 four times. This conductivity is comparable to that of the PEDOTPSS films reported by YH Kim et al. by adding EG into the Clevious PH 000 PEDOTPSS aqueous solution and subsequent treatment of the polymer films in an EG bath.
  • the two-step treatment of PEDOTPSS with EG as reported by YH Kim et al. was reported and it was observed that the conductivity was only 882 S/cm.
  • the lower conductivity than that of YH Kim et al. is probably related to the different Clevious PH1000 PEDOTPSS batches used in the different experiments.
  • the conductivity enhancement also depended on the temperature during the treatment (Figure 17).
  • the conductivity increased with the elevating temperature from 80 to 140°C, and then dropped slightly when the temperature was further increased to 200°C, but the conductivity was still more than 100 S/cm even when the treatment temperature was 200°C.
  • the HFA treated PEDOTPSS films were more thermally stable than those treated with other compounds, such as salts, zwitterions, acids and cosolvents as in the methods of the prior art.
  • PEDOTPSS films had a thickness of 60 nm. The thickness decreased to 50 nm after treatment with HFA once, and HFA treated PEDOTPSS films had a sheet resistance of 172 ⁇ sq "1 .
  • thick PEDOTPSS films were prepared by spin coating the Clevios PH1000 aqueous solution multiple times. An HFA treatment was carried out after spin coating each PEDOTPSS layer.
  • Four-layer PEDOTPSS films had a thickness of 164 nm and a conductivity of 1319 S/cm after the HFA treatment. The corresponding sheet resistance was 46 ⁇ sq "1 . It is comparable or even lower than that of ITO coated on PET, which is about 50 ⁇ sq "1 .
  • the PEDOTPSS films were smooth and homogeneous after the HFA treatment. Their transmittance in the visible range was not affected by the HFA treatment.
  • Figure 18 shows the transmittance spectra of HFA treated PEDOTPSS films with different thicknesses in the visible range.
  • the transmittance is above 90% in the visible wavelength range from 400 to 700 nm.
  • the transmittance of the 164 nm-thick PEDOTPSS film, which has a sheet resistance of 46 ⁇ sq "1 is more than 80% at 550 nm.
  • the high conductivity and transparency indicate that the HFA treated PEDOTPSS films are suitable as the transparent conductive electrode of optoelectronic devices.
  • Figure 19b shows the analysis of the temperature dependences of the resistances of untreated and HFA treated PEDOTPSS films with the one-dimensional variable range hopping (VRH) model, as described in Example 2.
  • the untreated PEDOTPSS film has a linear logR vs T "1/2 in the whole temperature range from 1 10 to 310 K, and the estimated T 0 value from this linear relationship is 1901 K.
  • the logR vs T "1 2 relations of the HFA-treated PEDOTPSS film had a linear relationship only at the low temperature range below 200 K, and the T 0 value estimated from the linear relationship is 99 K.
  • T 0 decreased with the increasing conductivity.
  • the treatment with HFA lowers the energy barrier for the interchain and inter-domain charge hopping.
  • the mechanism for the conductivity enhancement through the HFA treatment was studied by various chemical and physical characterizations.
  • the UV absorption spectra of untreated and HFA treated PEDOTPSS films are shown in Figure 20.
  • the two absorption bands in the UV range originate from the aromatic rings of PSS. Their intensity drops after the HFA treatment. This change indicates the decrease of the PSSH amount in PEDOTPSS.
  • the reduction of PSSH from the PEDOTPSS films after the HFA treatment is confirmed by XPS spectra of the PEDOTPSS films ( Figure 21 ).
  • the two XPS bands with binding energies between 166 and 172 eV are the S 2p band of the sulfur atoms in PSS, whereas the two XPS bands with binding energies between 162 and 166 eV are the S 2p band of the sulfur atoms in PEDOT.
  • the S 2p XPS intensity ratio of PEDOT to PSS increases after the HFA treatment.
  • the surface morphology of the PEDOTPSS films changed after the HFA treatment, as revealed by the AFM images ( Figure 22). Both the untreated and HFA treated PEDOTPSS films have quite a smooth surface. The rms roughness was 1 .63 and 1 .68 nm for the untreated and HFA treated PEDOTPSS films, respectively, but a remarkable difference in the AFM images can be observed.
  • the untreated PEDOTPSS film consisted of mainly polymer particles with a size of about 50 nm. These polymer particles turned into entangled wires with a diameter of tens of nanometers after the HFA treatment.
  • the AFM results are consistent with the energy barriers for the charge hopping obtained by the temperature dependences of the conductivities of the untreated and HFA treated PEDOTPSS films.
  • the conductive nanowires can promote the charge hopping in comparison with the particles.
  • the AFM images suggest the conformational change of the polymer chains after the HFA treatment. It is further evidenced by the electrochemical activity of untreated and HFA treated PEDOTPSS films, which is quite sensitive to the chain conformation.
  • CVs of PEDOTPSS films untreated, treated with HFA.3H 2 0 and an aqueous solution of 15 wt% HFA.3H 2 0 are presented in Figure 23.
  • the untreated PEDOTPSS film exhibited electrochemical activity only at potentials higher than -0.2 V vs. Ag/AgCI, whereas additional electrochemical activity appears at potentials down to -0.8 V vs. Ag/AgCI for the HFA treated PEDOTPSS films.
  • the electrochemical activities of the untreated and treated PEDOTPSS films are consistent with the conductivities of the PEDOTPSS films.
  • the higher conductivity of the PEDOTPSS films corresponds to more redox behavior in a more negative potential range.
  • the PEDOTPSS film treated with an aqueous solution of 15 wt% HFA.3H 2 0 had a conductivity of 532 S/cm, the peak potentials of the redox pair in the lowest potential range was -0.57 V and -0.54 V vs. Ag/AgCI, while this redox pair was not observed for the untreated PEDOTPSS film.
  • the peak potentials of this redox pair shifted to -0.68 V and -0.64 V vs.
  • the additional electrochemical activity for the HFA treated PEDOTPSS film was due to the decrease in the PSSH amount and the conformational change of the PEDOT chains.
  • the PEDOT chains with a linear or extended-coil conformation were electrochemically reduced and subsequently oxidized, while the reduction and oxidation were difficult for the PEDOT chains with a coil conformation surrounded by a relatively thick shell rich of PSSH.
  • HFA induced the reduction of PSSH and the conformational change of the PEDOT chains in PEDOTPSS films.
  • the geminal diol, HFP20H corresponding to HFA is an amphiphilic compound with the hydrophobic - CF 3 and hydrophilic -OH groups.
  • the hydrophobic -CF 3 groups of HFP20H preferentially interact with the hydrophobic PEDOT chains, whereas the hydrophilic - OH groups of HFP20H preferentially interact with the hydrophilic PSS chains of PEDOTPSS as shown in Scheme 3 below.
  • Scheme 3 Schematic representation of PEDOT:PSS before and after HFA treatment.
  • HFA induces the conformational change of the PEDOT chains in the PEDOTPSS films.
  • the hydrophobic PEDOT chains are stabilized by the hydrophilic PSS chains in water, so that the PEDOT chains follow the coil conformation of PSS chains due to the Coulombic attraction between them.
  • the coil conformation is conserved in the as- prepared PEDOTPSS films.
  • the PEDOT chains turn to an extended-coil or linear conformation as a result of the Coulombic screening between PSS and PEDOT by HFA.
  • the linear PEDOT chains have stronger inter-chain interactions, which facilitates the inter-chain charge transport, thus leading to an improved conductivity of the PEDOTPSS film.
  • the HFA treatment significantly enhances the conductivity while not affecting the transparency in the visible range of the PEDOTPSS films.
  • the HFA treated PEDOTPSS films are thus suitable for use as the transparent electrode of PSCs to replace ITO.
  • the current density (J)-voltage (V) curves of the PSCs are provided in Figure 24.
  • the photovoltaic performance is comparable to that of the control device using an. ITO anode.
  • the photovoltaic performance of the control device was: J sc of 10.00 mA/cm 2 , V oc of 0.59 V, FF of 0.70, and PCE of 4.13%.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Treatments Of Macromolecular Shaped Articles (AREA)
  • Coating Of Shaped Articles Made Of Macromolecular Substances (AREA)
  • Paints Or Removers (AREA)

Abstract

La présente invention concerne un procédé d'amélioration de la conductivité électrique d'un film de PEDOT:PSS consistant à utiliser un substrat possédant un film de PEDOT:PSS sur une surface du substrat ; et à traiter thermiquement ledit film avec un composé contenant du fluor ou un acide. La présente invention concerne également un film de PEDOT:PSS préparé selon le procédé.
PCT/SG2012/000175 2011-05-19 2012-05-18 Procédé d'amélioration de la conductivité électrique d'un film de pedot:pss WO2012158125A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US201161487743P 2011-05-19 2011-05-19
US61/487,743 2011-05-19
US61/487.743 2011-05-19

Publications (2)

Publication Number Publication Date
WO2012158125A1 true WO2012158125A1 (fr) 2012-11-22
WO2012158125A8 WO2012158125A8 (fr) 2013-01-24

Family

ID=47177208

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SG2012/000175 WO2012158125A1 (fr) 2011-05-19 2012-05-18 Procédé d'amélioration de la conductivité électrique d'un film de pedot:pss

Country Status (1)

Country Link
WO (1) WO2012158125A1 (fr)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104151565A (zh) * 2014-07-24 2014-11-19 常州大学 一种高导电率的pedot水分散体及其制备方法
CN105575462A (zh) * 2016-02-23 2016-05-11 华南理工大学 一种磺化丙酮甲醛缩合物分散聚3,4-乙撑二氧噻吩导电复合物及制备与应用
US9478743B2 (en) * 2014-09-02 2016-10-25 Gwangju Institute Of Science And Technology PEDOT:PSS based electrode and method for manufacturing the same
WO2017069716A1 (fr) * 2015-10-19 2017-04-27 Icelli Orhan Utilisation d'acide borique dans la production de film de pedot:pss
US9825226B2 (en) 2014-12-03 2017-11-21 Electronics And Telecommunications Research Institute Method for controlling an increase in conductivity of a polymer thin-film to provide a conductive film
CN111599922A (zh) * 2020-05-11 2020-08-28 暨南大学 一种调控pedot:pss薄膜组分纵向分布的方法及其薄膜与应用
CN113643855A (zh) * 2021-06-18 2021-11-12 南京邮电大学 一种柔性透明电极的制备方法及其应用
CN113740540A (zh) * 2021-09-03 2021-12-03 浙江理工大学 一种用于丝素蛋白检测的有机电化学晶体管的制备方法
CN113861461A (zh) * 2021-08-18 2021-12-31 浙江大学 一种梯度电导率pedot:pss自组装薄膜、制备方法及应用

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7560776B2 (en) * 2005-03-30 2009-07-14 Seiko Epson Corporation Semiconductor device, electronic apparatus, method of manufacturing semiconductor device, and method of manufacturing electronic apparatus
US20100294350A1 (en) * 2009-05-25 2010-11-25 Ko Min-Jae Photo-electrode comprising conductive non-metal film, and dye-sensitized solar cell comprising the same

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7560776B2 (en) * 2005-03-30 2009-07-14 Seiko Epson Corporation Semiconductor device, electronic apparatus, method of manufacturing semiconductor device, and method of manufacturing electronic apparatus
US20100294350A1 (en) * 2009-05-25 2010-11-25 Ko Min-Jae Photo-electrode comprising conductive non-metal film, and dye-sensitized solar cell comprising the same

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
JIAN-GING CHEN ET AL.: "Using modified poly (3,4-ethylene dioxythiophene): Poly (styrene sulfonate) film as a counter electrode in dye-sensitized solar cells", SCIENCE DIRECT, SOLAR ENERGY MATERIALS AND SOLAR CELLS, vol. 91, 17 May 2007 (2007-05-17), TAIPEI 10617, TAIWAN, pages 1472 - 1477 *

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104151565A (zh) * 2014-07-24 2014-11-19 常州大学 一种高导电率的pedot水分散体及其制备方法
US9478743B2 (en) * 2014-09-02 2016-10-25 Gwangju Institute Of Science And Technology PEDOT:PSS based electrode and method for manufacturing the same
US9825226B2 (en) 2014-12-03 2017-11-21 Electronics And Telecommunications Research Institute Method for controlling an increase in conductivity of a polymer thin-film to provide a conductive film
WO2017069716A1 (fr) * 2015-10-19 2017-04-27 Icelli Orhan Utilisation d'acide borique dans la production de film de pedot:pss
CN105575462A (zh) * 2016-02-23 2016-05-11 华南理工大学 一种磺化丙酮甲醛缩合物分散聚3,4-乙撑二氧噻吩导电复合物及制备与应用
CN111599922A (zh) * 2020-05-11 2020-08-28 暨南大学 一种调控pedot:pss薄膜组分纵向分布的方法及其薄膜与应用
CN111599922B (zh) * 2020-05-11 2023-11-24 暨南大学 一种调控pedot:pss薄膜组分纵向分布的方法及其薄膜与应用
CN113643855A (zh) * 2021-06-18 2021-11-12 南京邮电大学 一种柔性透明电极的制备方法及其应用
CN113861461A (zh) * 2021-08-18 2021-12-31 浙江大学 一种梯度电导率pedot:pss自组装薄膜、制备方法及应用
CN113861461B (zh) * 2021-08-18 2022-07-05 浙江大学 一种梯度电导率pedot:pss自组装薄膜、制备方法及应用
CN113740540A (zh) * 2021-09-03 2021-12-03 浙江理工大学 一种用于丝素蛋白检测的有机电化学晶体管的制备方法
CN113740540B (zh) * 2021-09-03 2024-05-03 浙江理工大学 一种用于丝素蛋白检测的有机电化学晶体管的制备方法

Also Published As

Publication number Publication date
WO2012158125A8 (fr) 2013-01-24

Similar Documents

Publication Publication Date Title
Xia et al. Highly conductive poly (3, 4-ethylenedioxythiophene): poly (styrene sulfonate) films treated with an amphiphilic fluoro compound as the transparent electrode of polymer solar cells
WO2012158125A1 (fr) Procédé d'amélioration de la conductivité électrique d'un film de pedot:pss
Yu et al. PEDOT: PSS films with metallic conductivity through a treatment with common organic solutions of organic salts and their application as a transparent electrode of polymer solar cells
Jiang et al. Recent advances of synthesis, properties, film fabrication methods, modifications of poly (3, 4‐ethylenedioxythiophene), and applications in solution‐processed photovoltaics
Song et al. Conductive channel formation for enhanced electrical conductivity of PEDOT: PSS with high work-function
Wang et al. Ammonia-treated graphene oxide and PEDOT: PSS as hole transport layer for high-performance perovskite solar cells with enhanced stability
Zhang et al. Highly conductive PEDOT: PSS transparent electrode prepared by a post-spin-rinsing method for efficient ITO-free polymer solar cells
Ouyang Solution-processed PEDOT: PSS films with conductivities as indium tin oxide through a treatment with mild and weak organic acids
Fan et al. Bendable ITO-free organic solar cells with highly conductive and flexible PEDOT: PSS electrodes on plastic substrates
Huseynova et al. Rising advancements in the application of PEDOT: PSS as a prosperous transparent and flexible electrode material for solution-processed organic electronics
Nevrela et al. Secondary doping in poly (3, 4‐ethylenedioxythiophene): Poly (4‐styrenesulfonate) thin films
Elschner et al. Solution-deposited PEDOT for transparent conductive applications
Cao et al. Transparent electrodes for organic optoelectronic devices: a review
Xia et al. Highly conductive PEDOT: PSS films prepared through a treatment with geminal diols or amphiphilic fluoro compounds
Howden et al. oCVD poly (3, 4-ethylenedioxythiophene) conductivity and lifetime enhancement via acid rinse dopant exchange
Li et al. Graphene-based transparent electrodes for hybrid solar cells
EP1914781A2 (fr) Électrode transparente à nanotubes en carbone utilisant un dispersant conducteur et son procédé de fabrication
JP2015526836A (ja) 銀ナノワイヤをベースとする透明導体材料の電気的および光学的性能を改善する方法
Chalh et al. Plasmonic Ag nanowire network embedded in zinc oxide nanoparticles for inverted organic solar cells electrode
Lim et al. Flexible PEDOT: PSS/ITO hybrid transparent conducting electrode for organic photovoltaics
Khasim et al. Post treated PEDOT-PSS films with excellent conductivity and optical properties as multifunctional flexible electrodes for possible optoelectronic and energy storage applications
KR20110051821A (ko) 유기태양전지의 Ｐ형 전도막으로 사용되는 ＮｉＯ 전도막, 이의 제조방법 및 이를 포함하는 광전변환효율이 향상된 유기태양전지
WO2013123046A2 (fr) Matériaux tampons de cathode et dispositifs et procédés associés
Liu et al. One-step solution-processed low surface roughness silver nanowire composite transparent electrode for efficient flexible indium tin oxide-free polymer solar cells
KR20160110863A (ko) 3차원 나노 리플 구조의 금속산화물 박막, 이의 제조방법 및 이를 포함하는 유기태양전지

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 12786503

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 12786503

Country of ref document: EP

Kind code of ref document: A1