Patent Application
20100055562
1. Technical Field
The present disclosure relates generally to nanotechnology and, more particularly, to nanowire layer adhesion.
2. Description of Related Art
The current trend of electronic products becoming smaller and thinner has led to the use of various thin film members. In general, thin films may be formed using deposition methods such as sputtering, vapor deposition, and the like.
As a representative thin film member, a transparent electrode may be manufactured by depositing transparent conductive materials such as Indium Tin Oxide (ITO) on a transparent substrate.
While crystalline thin films such as ITO, and the like, exhibit adhesive strength with the substrate, such films may be difficult to employ in electronic products requiring flexibility.
On the other hand, conventional flexible thin films formed, for example, from nano fibers, tend to exhibit weaker adhesive strength between the nano fiber and the substrate, thereby reducing the durability of the electronic products and increasing contact resistance, resulting in deterioration of the electrical characteristics of the products.
In one embodiment, a method for forming a nanowire layer includes etching a substrate with an ionized gas, coating the etched substrate with a solution containing nanowires, and drying the substrate.
In another embodiment, a method for forming a carbon nanotube (CNT) layer includes preparing CNTs, purifying the CNTs, dispersing the purified CNTs in a solvent to form a CNT-containing solution, coating an etched substrate with the CNT-containing solution, and drying the coated substrate.
The Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. It will be readily understood that the components of the present disclosure, as generally described herein, and illustrated in the Figures, may be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and make part of this disclosure.
The embodiment(s) described, and references in the specification to “one embodiment”, “an embodiment”, “an example embodiment”, etc., indicate that the embodiment(s) described may include a particular feature, structure, or characteristics, but every embodiment may not necessarily include the particular feature, structure, or characteristics, but every embodiments may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is understood that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
Substrate 100 may include, by way of non-limiting example, a silicon substrate, a glass substrate, an oxide substrate, a polymeric substrate, and the like. The material employed for substrate 100 may vary depending on a use of the substrate 100. By way of example, substrate 100 applicable for use in a transparent electrode may include transparent substrates such as a glass substrate, an oxide substrate, a transparent resin film, and the like. Further, substrate 100 may be cleaned to remove foreign substances on substrate 100 before performing the etching process described herein. The transparent resin film may include, by way of non-limiting example, a polyethylene terephthalate (PET) film.
The term substrate, as used herein, may include both a thick or bulky-typed substrate and a thin film having a nano or micro sized structure. Such a thin film may include, by way of non-limiting example metal thin films formed through metal deposition using metals such as aluminum, copper, and the like. Such metal thin films may be transparent.
Ionized gas 110 may be generated by providing electric power from power supply 170 to electrodes 162, 164 in etching chamber 150 including a source gas. The electric field is formed when the electric power is provided to electrodes 162, 164. The source gas may be, by way of non-limiting example, provided to etching chamber 150 from an external source. When the electric field is formed in etching chamber 150, particles or elements within the source gas may be converted into ionized (or radicalized) particles 112. Ionized particles 112 may collide with substrate 100 in response to the electric field. Further, substrate 100 may be electrically charged while the electric field is formed in etching chamber 150. Subsequently, surface 102 of substrate 100 may be physically etched and/or chemically modified by collisions with ionized particles 112
The strength of the applied electric field may vary according to a type of the source gas. As a non-limiting example, when using an oxygen(O2) containing gas as the source gas, the source gas may be ionized by an electric field having an electric power of about 150 to 300 watts.
Ionized gas 110 may include, by way of example and not a limitation, group 16 elements, group 17 elements or any combination thereof. As a non-limiting example, ionized gas 110 may include elements such as oxygen (O), sulfur (S), selenium (Se), tellurium (Te), fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and the like. Alternatively, the ionized gas 110 may include inert elements of group 18 elements such as helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and the like.
As a non-limiting example, the etching process described herein may be performed in a Reactive Ion Etching (RIE) device. An RIE device supplies Radio Frequency (RF) power to two parallel flat plate electrodes facing each other. The source gas may be provided to the space between the two parallel flat plate electrodes. When Radio Frequency (RF) power is supplied to the two parallel flat plate electrodes, the source gas may be activated to etch a target substrate. The activated source gas (ionized gas) 110 may chemically react with a portion of the substrate 100. In some implementations, the internal pressure of the RIE may be maintained in a vacuum state of about 30 to 50 mTorr while the etching process is performed.
Measurement of Changes in Roughness of Transparent Substrate Before and After Etching
Changes in roughness of a glass substrate after performing etching using an ionized gas may be observed. For example, substrate roughness before and after etching may be measured by scanning a relatively small surface area (e.g., a 4 μm2 area) of the substrate using an Atomic force microscope (AFM). Etching as described herein may increase an average roughness of a substrate by an order of magnitude or more, although claimed subject matter is not limited in this regard. For example, etching as described herein has been measured to increase glass substrate roughness from about 0.8 nm before etching to about 20 nm after etching.
Measurement of Changes in Light Transmittance of Glass Substrate Before and After Etching
Changes in light transmittance of the transparent substrate after performing etching may also be observed. For example, etching as described herein may reduce transmittance of a glass substrate at shorter wavelengths by about 1% although claimed subject matter is not limited in this regard.
Nanowire layer 200 may be formed by coating nanowire materials 210 onto substrate 100 using a nanowire-containing solution, and drying coated substrate 100. The solution containing the nanowire materials may be, by way of non-limiting example, a colloidal solution formed by evenly dispersing the nanowire materials in a solvent. The solvents used may vary depending on a type of the nanowire materials 210 employed. For example, solvents employed when using CNT for the nanowire materials 210 may include 1,2-Dichlorobenzene, Chloroform, 1-Methylnaphthalene, 1-Bromo-2-methoylnaphthalene, N-Methylpyrrolidinone, Dimethylformamide, Tetrahydrofuran, 1,2-Dimethylbenzene, Pyridine, Carbon disulfide, 1,3,5-Trimethylbenzene, and the like. Further, the nanowire-containing solution used to coat a substrate may include a single solvent or a mixture of solvents.
In addition, although claimed subject matter is not limited in this regard, nanowire materials 210 may undergo a preparation process before being mixed with the solvent to form the solution. To do so, nanowire materials 210 may be subjected to an ultrasonic treatment in an acidic solution such as, by way of non-limiting example, a nitric acid solution. Bundle-typed nanowire materials provided by nanowire-makers may be separated into individual nanowires by the ultrasonic treatment.
Further, the preparation process may act to remove catalyst from nanowire materials 210 and nanowire materials 210 may subsequently be coupled with a functional group such as, by way of non-limiting example, a hydroxy group derived form an acid solution. The coupled functional group may enhance the affinity of nanowire materials 210 for modified surface 102 of substrate 100. As a non-limiting example, functional groups such as a hydroxy group, a carboxyl group, and the like may be combined with nanowire materials 210.
The nanowire-containing solution may be coated on the surface of substrate 100 by various schemes such as, by way of non-limiting example, spin coating, spraying, dip-coating, and the like. The dip-coating scheme may be performed by immersing substrate 100 in the nanowire-contained solution. Once coated with the nanowire-containing solution, the solvent elements may be volatilized by drying leaving nanowire layer 200 including nanowire materials 210 on substrate 100.
Hereinafter, according to an illustrative embodiment, preparing a CNT-containing solution, as an example of the nanowire-containing solution, will be described in detail. However, this example is for illustrative purpose only, and should not be construed as limiting the scope of claimed subject matter.
Preparing a CNT-Containing Solution
In order to prepare an amount of SW-CNT for incorporation into a nanowire-containing solution the SW-CNT may be dispersed in a nitric acid solution and reacted with the nitric acid solution for 30 minutes at 50° C. Next, ultrasonic waves may be applied to the reaction solution so as to remove, as a non-limiting example, a catalyst associated with or bonded to the CNT. After completion of the reaction, the reaction solution may be neutralized with deionized water. Then, the neutralized reaction solution may be subjected to a filtering process, such as vacuum filtering, to remove the CNT from the solution. The removed CNT may be dried for about 48 hours at 80° C. in a vacuum oven chamber. The dried CNT may then be uniformly dispersed in a 1,2-Dichlorobenzene solvent to produce a CNT-containing solution of a colloidal type. The CNT-containing solution may be subjected to an ultrasonic treatment for about 10 hours to additionally disperse the CNTs in the solvent.
When coated on the substrate nanowire materials 210 may adhere to surface 102 of substrate 100 to form nanowire layer 200, where layer 200 may include a large number of nanowires where some of the nanowires in nanowire layer 200 across or otherwise make physical and/or electrical contact with other nanowires in nanowire layer 200. By forming nanowire layer 200 on surface 102 of substrate 100, thin film member 300 may be obtained. Thin film member 300 may be utilized for various applications such as, but not limited to, applications that make use of transparent electrodes.
Again referring to
As described above, a transparent electrode having a flexible characteristic and including CNTs as a conductive layer may be manufactured. The transparent electrode possesses excellent durability and electric characteristics.
From the foregoing, it will be appreciated that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
