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  • C08G61/12—Macromolecular compounds containing atoms other than carbon in the main chain of the macromolecule
  • C08G61/122—Macromolecular compounds containing atoms other than carbon in the main chain of the macromolecule derived from five- or six-membered heterocyclic compounds, other than imides
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  • C07C309/01—Sulfonic acids
  • C07C309/02—Sulfonic acids having sulfo groups bound to acyclic carbon atoms
  • C07C309/03—Sulfonic acids having sulfo groups bound to acyclic carbon atoms of an acyclic saturated carbon skeleton
  • C07C309/04—Sulfonic acids having sulfo groups bound to acyclic carbon atoms of an acyclic saturated carbon skeleton containing only one sulfo group
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  • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
  • C09K11/06—Luminescent, e.g. electroluminescent, chemiluminescent materials containing organic luminescent materials
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  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/10—Organic polymers or oligomers
  • H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/10—Organic polymers or oligomers
  • H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
  • H10K85/115—Polyfluorene; Derivatives thereof
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  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/60—Organic compounds having low molecular weight
  • H10K85/631—Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine
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  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K50/00—Organic light-emitting devices
  • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
  • H10K50/14—Carrier transporting layers
  • H10K50/16—Electron transporting layers
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K50/00—Organic light-emitting devices
  • H10K50/10—OLEDs or polymer light-emitting diodes [PLED]
  • H10K50/17—Carrier injection layers
  • H10K50/171—Electron injection layers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/50—Photovoltaic [PV] energy
  • Y02E10/549—Organic PV cells
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

• This invention relates to organic semiconductors and, in particular, although not exclusively, to polymeric semiconductors which are usable in optoelectronic, e.g . photo-responsive, devices.
• LEDs light emitting diodes
• PV photovoltaic diodes
• FETs field effect transistors
• lasers lasers
• conjugated polymers exemplify the considerable material advantages that organic semiconductor may have over inorganic semiconductors including chemically tunable optoelectronic properties and low-temperature, solution-based processing suitable for printed electronics.
• CPEs Conjugated polyelectrolytes
• charge transport e.g. electron transport or electron injection
• the electronic properties of the CPEs, in combination with their solubility in polar solvents, makes them attractive candidates for materials in e.g. LEDs and PVs.
• optoelectronic devices including CPEs have slow turn-on times. Without wishing to be bound by any particular theory, it is postulated that this is at least in part owing to the migration of the counter ions, which may also lead to redistribution of the internal field . Moreover, these mobile counter ions also appear to make the device operation mechanism more complicated, as they may alter the work function of the one or both of the electrodes. Furthermore, in OLEDs, for example, the counter ions may impact on the doping characteristics of the light emitting layer. It is an object of the present invention to provide materials for electronic devices having the advantages of CPEs, while minimising drawbacks such as those described above. It is a further object of the present invention to provide electronic devices including such materials.
• the invention provides an optoelectronic device comprising a charge transfer layer including a first semiconductive polymer comprising one or more zwitterions.
• the invention provides an optoelectronic device comprising a charge transfer layer including a first semiconductive polymer comprising one or more zwitterions covalently attached to the polymer.
• zwitterion shall denote a moiety which exists in a stable, charge neutral form having at least one formal positive charge centre and at least one negative charge centre.
• zwitterionic substituent refers to a distinct moiety having zwitterionic character attached to a molecule (e.g. a polymer) .
• the one or more zwitterions are covalently attached to the semiconductive polymer backbone.
• the first semiconductive polymer comprises a first repeat unit having at least one zwitterionic substituent.
• the zwitterionic substituent comprise at least one quaternary amine group.
• the zwitterionic substituent comprise a sulfonate group.
• the zwitterionic substituent comprises a cationic centre and an anionic centre separated by at least 1, e.g. 2, 3, 4, 5, or more atomic (e.g. carbon) centres, for example an integer number between 2 and 20, say 2 and 10.
• the first repeat unit comprises a fluorene residue.
• the first repeat unit comprises the structure : where R 1 comprises the or a zwitterionic substituent.
• R 2 comprises the or a zwitterion group (e.g. a different zwitterion group), H or a d to Cio straight or branched alkyl, alkenyl or alkynyl chain .
• a zwitterion group e.g. a different zwitterion group
• R 1 and R 2 both comprise zwitterionic substituents, e.g. the same zwitterionic substituents.
• one or more the of the zwitterionic substituents comprises a first cationic charge centre separated from a first anionic charge centre by more than 2 atomic (e.g. carbon) centres.
• the first semiconductive polymer comprises a second repeat unit.
• the second repeat unit comprises a fluorene residue, e.g. 9,9- dioctylfluorene.
• the first semiconductive polymer comprises an alternating copolymer of the first repeat unit and the or a second repeat unit.
• the charge transport layer is positioned between a light emissive layer and a cathode, e.g. the charge transport layer is positioned directly adjacent the light emissive layer and/or the cathode.
• the charge transport layer is positioned between a photovoltaic layer and a cathode, e.g. the charge transport layer is positioned directly adjacent the photovoltaic layer and/or the cathode.
• the cathode comprises one or more materials selected from aluminium, calcium, indium tin oxide (ITO) .
• ITO indium tin oxide
• the charge transport layer (e.g. the electron transport layer) is at least lnm (e.g. at least 2nm, at least 5nm, at least 7nm or at least 9nm) thick.
• the charge transport layer (e.g. the electron transport layer) is between lnm and 20nm thick. More preferably, the echarge transport layer is between 2nm and lOnm thick.
• the invention provides a semiconductive polymer comprising a first repeat unit having at least one zwitterionic substituent, where the zwitterionic substituent comprises a first cationic charge centre separated from a first anionic charge centre by more than 2 atomic (e.g. carbon) centres.
• the zwitterionic substituent comprise at least one quaternary amine group.
• the zwitterionic substituent comprise a sulfonate group.
• the first repeat unit comprises a fluorene residue.
• the first repeat unit comprises the structure : where R 1 comprises the or a zwitterionic substituent.
• R 2 comprises the or a zwitterion group (e.g. a different zwitterion group), H or a d to Cio straight or branched alkyl, alkenyl or alkynyl chain.
• a zwitterion group e.g. a different zwitterion group
• R 1 and R 2 both comprise zwitterionic substituents, e.g. the same zwitterionic substituents.
• the semiconductive polymer comprises a second repeat unit.
• the second repeat unit comprises a fluorene residue, e.g. 9,9- dioctylfluorene.
• the semiconductive polymer comprises an alternating copolymer of the first repeat unit and the or a second repeat unit.
• the invention provides an electron injection material comprising a semiconductive polymer as described above.
• the invention provides an electron transport material comprising a polymer as described above.
• the invention comprises a method of manufacturing an electrically semiconductive zwitterionic polymer comprising : polymerising at least a first conjugated monomer to form a conductive polymer and reacting the polymer with at least one zwitterion forming reactant to form the conductive zwitterionic polymer.
• the first conjugated monomer comprises at least one tertiary amine substitution, e.g. such that the semiconductive polymer formed therefrom comprises a tertiary amine substituted polymer.
• the first zwitterion forming reactant comprises a negative charge carrying species or precursor thereof, for example for reacting with the or a tertiary amine group.
• the negative charge carrying species or precursor thereof comprises a sulfone.
• the method comprises copolymerising the first monomer with at least one further monomer, e.g. an amine free monomer.
• at least one further monomer e.g. an amine free monomer.
• the polymerisation comprises a Suzuki polymerisation.
• the polymerisation comprises a Yamamoto or Stille polymerisation.
• Figure 1 shows a synthetic pathway for a conductive polymer according to the invention
• Figure 2 shows a schematic diagram of an optoelectronic device according to the present invention
• Figure 3 shows a plot of luminance against voltage for devices according to the invention and the prior art
• Figure 4 shows a plot of efficiency against voltage for devices according to the invention and the prior art
• Figure 5 shows a plot of absorption intensity against wavelength for materials according to the present invention and the prior art
• Figure 6 shows a plot of photoluminescent intensity against wavelength for materials according to the present invention and the prior art
• Figure 7 shows plots of luminescence and current density against time for devices according to the present invention
• Figure 8 shows plots of capacitive charge and charge density versus voltage for devices according to the present invention and the prior art.
• a charge-neutral conjugated polyelectrolyte was synthesised according to the following method.
• Neutral tertiary amine polymers were synthesised by Pd-mediated Suzuki condensation polymerisation of 2,7-bis(l,3,2-dioxaborolan-2-yl)-9,9- dioctylyfluorene (1) with 2,7-dibromo-9,9-bis((N,N-dimethylamino)ethanyl) fluorene (2), under conditions as are well known in the art.
• the neutral tertiary amine polymer (3) so-formed is soluble in organic solvents such as chloroform, THF and toluene, but insoluble in methanol, DMSO and water.
• the polymer was then quaternised by refluxing for 3 days at 70°C in toluene/methanol with 1,4-butane sultone.
• the resulting zwitterionic conjugated polyelectrolyte (4) was soluble in methanol and DMSO. Elemental analysis of the polyelectrolyte showed a near 100% conversion of the tertiary amines of the first polymer into the sulfobetaine zwitterionic groups.
• FIG. 2 shows a simple optoelectronic device 10 according to the invention.
• the device 10 comprises in series an aluminium cathode layer 12, a 2nm thick electron transfer layer 14 comprising the zwitterionic polyelectrolyte, a lOOnm thick light emissive layer 16 comprising poly(9,9-dioctylfluorene)- co-benothiadazole (F8BT) and an ITO/PEDOT: PSS anode 18.
• the device 10 was manufactured by successively spin coating the anode 18, light emissive layer 18 and electron transfer layer 14 onto a glass substrate, followed by depositing the aluminium cathode 12 onto the electron transfer layer 14.
• the device 10 as described above was tested for luminance against voltage.
• the results of the test are plotted in Figure 3.
• the turn-on voltage (defined as the voltage at which the luminance reached lcd/m 2 ) was 2.3V and the brightness increased to 1900cd/m 2 at 3V and a maximum of 80000cd/m 2 at 5.8V.
• the same device 10 was tested for current efficiency against voltage. The results of the test are plotted in Figure 4.
• the efficiency at 5.8V was found to be 8.8 cd/A (the corresponding current density being 910.5 cd/m 2 ), the maximum efficiency being 10.4 cd/A (at a brightness of 26000 cd/m 2 ). It is notable that the device efficiency is stable at operating voltages, with no significant decrease observed up to 5.8V.
• a first comparative device was prepared to comprise, in series, an aluminium/calcium cathode, an F8BT emissive layer and a PEDOT: PSS anode.
• a second comparative device was prepared to comprise, in series, an aluminium cathode, an F8BT emissive layer and a PEDOT: PSS anode.
• the first comparative device was tested for luminance against voltage and efficiency against voltage. The results are plotted in Figures 3 and 4 respectively.
• the first comparative device performed very poorly in both tests, owing to poor electron injection.
• the turn-on voltage was around 7.5V, far higher than the 2.3V observed for Example 1.
• the second comparative device was also tested for luminance against voltage and efficiency against voltage. The results are plotted in Figures 3 and 4 respectively.
• the turn-on voltage of the second comparative device was found to be substantially the same as that of Example 1, which can be explained by the small difference between the LUMO of F8BT (2.94eV) and the work function of Ca (2.87eV).
• the maximum brightness of the second comparative device was found to be only 30,000cd/m 2 , less than half of that of the device of Example 1.
• the energy conversion efficiency of the second comparative device was found to be approximately half that observed in Example 2.
• Example 4a A solution of the zwitterionic polyelectrolyte in methanol was tested for its solution absorption (Example 4a) and solution photoluminescent properties (Example 4b). The results are plotted in Figures 5 and 6 respectively. Comparative Example 4
• the HOMO of the zwitterionic polyelectrolyte and F8BT were found, by cyclic voltammetry, each to be 5.6eV .
• the corresponding LUMOs were found through the absorption onset to be 2.67eV and 2.64eV respectively.
• Example 5a An device similar to that tested in Example 1, but having a 7nm thick electron transfer layer comprising the zwitterionic polyelectrolyte, was tested to measure its luminescence (Example 5a) and current density dynamics (Example 5b) during rectangular lHz voltage pulses of 4.9V. The results are plotted in Figure 7.
• Example 5 The time-dependence of the current measured in Example 5 (and as shown in Figure 7), and equivalent data for a similar device having an electron transfer layer comprising the zwitterionic polymer lOnm thick (Examples 6 and 7 respectively) are integrated to show charge accumulated in the device.
• the capacitive charge accumulation and charge density are shown in a plot against voltage in Figure 8.
• the zwitterionic polyelectrolyte of the invention therefore offers excellent performance as a charge transport material, while maintaining fast switching times and high efficiency, and without compromising emission frequency.

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• 2010
  • 2010-12-16 GB GB1021382.5A patent/GB2486480A/en not_active Withdrawn
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