Patent number 8603705 is assigned to
The following quote was obtained by the news editors from the background information supplied by the inventors: "There are a number of advantages to replacing traditional (i.e., inorganic-based) electronic devices with those formed form organic materials (e.g., electroactive or conjugated polymers). For example, organic materials are generally lighter, more flexible, and cheaper to fabricate than inorganic materials. These materials and the devices produced therefrom, however, are not immune to the fabrication and/or integration challenges that exist for traditional electronics, especially with the ever-increasing demands of consumers for improved devices.
"One such remaining challenge involves controlling the microstructure of organic materials in the solid state. Given the importance of microstructure on the intermolecular charge transport properties of films of conjugated polymers, the ability to control the microstructure of such materials should lead to improved conductivities or at least to similar conductivities with fewer charge carriers.
"A common method for increasing the charge transport, or carrier mobility, in a polymer film entails thermally annealing the polymer at a high temperature, which is typically close to the glass transition temperature of the polymer, followed by a slow crystallization. This, however, requires the process to be conducted under extremely low oxygen and moisture concentrations so as to ensure that the polymer does not oxidize. Dielectric surface modifications using self-assembled monolayers provide another technique for mobility enhancement. Controlled deposition of monolayers, however, is often difficult to achieve and also requires moisture free environments. Other techniques include the use of high boiling point solvents, different deposition techniques, and the generation of ordered precursors in solution by using non-solvent aggregation. Unfortunately, the increases in mobility that are achieved by each of the above-referenced techniques are not significant. High mobility can be achieved by using high purity polymers with high regioregularity (e.g., greater than 98%), which can be process intensive to synthesize.
"Thus, despite the advancements made in controlling the microstructure (and, by extension, the mobility) of organic materials in the solid state, there remains a need for improved methods for doing so. Such methods can lead to improved devices that exhibit higher mobilities and potentially higher conductivities. It is to the provision of such methods and devices that the various embodiments of the present inventions are directed."
In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "The various embodiments of the present invention provide new and facile approaches to enhance the crystallinity of solution-processed polymer films. Such processes present significant advantages over existing techniques for improving crystallinity, and result in improved films and devices.
"According to some embodiments of the present invention, a method includes contacting a polymer with a solvent to at least partially solvate the polymer in the solvent. The method can also include exposing the at least partially solvated polymer and solvent to ultrasonic energy for a duration effective to form a plurality of ordered assemblies of the polymer in the solvent. The method can also include forming a solid film of the polymer, wherein the solid film comprises the plurality of ordered assemblies of the polymer. In some implementations, the method also involves forming an electronic device from the solid film of the polymer.
"The polymer can be chosen from a variety of polymers. For example, the polymer can be a conjugated polymer. The conjugated polymer can be a rigid-rod conjugated polymer. In some cases, the polymer can be a polythiophene or derivative thereof. For example, the polymer can be poly(3-hexylthiophene). In some situations, a weight average molecular weight of the polymer will be at least about 10 kiloDaltons. In other situations, a weight average molecular weight of the polymer will be at least about 15 kiloDaltons.
"The solvent will, in some embodiments, completely solvate the polymer during the contacting step. In some other cases, the solvent will not allow solute-solute interactions to dominate over solvent-solute interactions.
"The duration of the exposing step can be less than or equal to about 15 minutes. During the exposing step, the ultrasonic energy can cause individual chains of the polymer to disentangle from each other, and aggregate to form the plurality of ordered assemblies. In certain situations, each of the plurality of ordered assemblies will be at least nanocrystalline in size.
"The solid film of the polymer is capable of exhibiting a carrier mobility of at least one order of magnitude greater than a solid film formed without the exposing step.
"According to some embodiments, a polymer film can be formed. According to other embodiments, an electronic device can be formed.
"Still according to other embodiments, another method includes contacting poly(3-hexylthiophene) with a solvent to at least partially solvate the poly(3-hexylthiophene) in the solvent. In this method, the poly(3-hexylthiophene) has a weight average molecular weight of at least 15 kiloDaltons and a regioregularity of at least 92%. This method can also include exposing the at least partially solvated poly(3-hexylthiophene) and solvent to ultrasonic energy for a duration effective to form a plurality of ordered assemblies of the poly(3-hexylthiophene) in the solvent. In addition, the method can involve forming a solid film of the poly(3-hexylthiophene), wherein the solid film comprises the plurality of ordered assemblies of the poly(3-hexylthiophene) and wherein the solid film comprises a carrier mobility of at least one order of magnitude greater than a solid film of poly(3-hexylthiophene) formed without the exposing. In still other cases, the method can further include forming an electronic device from the solid film of the polymer.
"Using this method, the solvent can be one or more of chloroform, thiophene, chlorobenzene, dichlorobenzene, trichlorobenzene, or toluene.
"Using this method, the plurality of ordered assemblies can be at least nanocrystalline in size.
"According to some embodiments, a poly(3-hexylthiophene) film can be formed.
"According to other embodiments, an electronic device can be formed.
"Other aspects and features of embodiments of the present invention will become apparent to those of ordinary skill in the art, upon reviewing the following detailed description in conjunction with the accompanying figures."
URL and more information on this patent, see: Aiyar, Avishek; Nambiar, Rakesh; Collard, David; Reichmanis, Elsa. Polymer Film-Producing Methods and Devices Produced Therefrom. U.S. Patent Number 8603705, filed
Keywords for this news article include: Nanotechnology, Nanocrystalline, Emerging Technologies,
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