Press releaseKonarka Technologies, Inc. (Lowell, MA) researchers have developed photovoltaic cells using carbon nanotubes that may be formed into a flexible fabric or textile. The photovoltaic material includes a fiber core having an outer surface, a light-transmissive electrical conductor, a photosensitized nanomatrix material, and a charge carrier material, where the photosensitized nanomatrix material and the charge carrier material are disposed between the outer surface of the fiber core and the light-transmissive electrical conductor. The photosensitized nanomatrix material includes one or more types of interconnected metal oxide nanoparticles, and may also include a photosensitizing agent. The photosensitizing agent may be a dye or an organic molecule, such as a xanthine, cyanine, merocyanine, phthalocyanine, or pyrrole, according to U.S. Patent 7,622,667.
Figure 11 shows an exemplary method for forming a flexible fiber including a photovoltaic material using a continuous manufacturing process.
Press release
Press releaseFIG. 11 shows a method 1100 for forming a photovoltaic material in the form of a fiber using a continuous manufacturing process. Referring to FIG. 11, a fiber 1101 is provided, for example, by a supply spool 1102. The fiber 1101 may be an electrically insulative fiber corecoated with an electrical conductor, an electrically conductive fiber core, or a combination of both. According to the illustrative embodiment, the fiber 1101 is coated with a suspension of titanium dioxide nanoparticles and poly(n-butyl titanate) (serving as a reactive polymeric linking agent) by passing it into such a fluid suspension contained in a cup 1104 with a small hole in its bottom. Upon exiting the cup 1104, the interconnected nanoparticle-coated fiber 1105 enters an oven 1106 to remove excess suspending medium (e.g., water or other solvent).
If the solvent for the polyelectrolyte is a monomer, it is preferably chosen such that it can be photopolymerized and such that the resulting polymer structure does not detract from the electrical properties of the polyelectrolyte. Hence, in the illustrative embodiment where the solvent includes a monomer, the photoconversion material-coated fiber 1112 is passed through a chamber containing UV lamps 1114, which initiate photopolymerization of the monomer. The resultant fiber 1115 is then coated with the photoconversion material including a solid state electrolyte, and may be readily spooled onto a take-up spool 1116.
The photoconversion material-coated fiber 1115 then passes through or is placed in a vacuum chamber 1118 where a very thin layer of platinum, followed by a transparent, conductive coating of ITO, are deposited on the fiber. The platinum may be, for example, between about 15 .ANG. and about 50 .ANG. thick. The ITO serves as the significant light transmitting electrical conductor. The completed photovoltaic fiber 1119 may then be passed through a polymer solution 1120 to provide a transparent, protective coating, such as by wire extrusion or other means known to the art. Thus a flexible photovoltaic material 1121 is taken up on a finished spool 1122 and is ready for subsequent use in a weaving or matting operation.
The practical and widespread implementation of nanotechnology requires precise three-dimensional arrangement of functional materials. There is significant demand for an inkjet printer that can print structures with complex topologies. To meet this demand Japan’s National Institute of Advanced Industrial Science and Technology (AIST) has successfully developed a super-fine inkjet printer, which can discharge micro ink droplets, far smaller than those of normal inkjet printers. To allow widespread use of this technology, AIST has designed a portable unit that is about 600 times smaller than the first generation SIJ printer and fits in the palm of a hand. By using this ultra-small SIJ units, micrometer scale patterning or precise material deposition in the femtoliter order is feasible. Mask-less patterning, such as micrometer scale circuit pattern can be achieved without the photolithographic process.
Photo: AIST Palm Sized Superfine Inkjet Printer and Original Superfine Inkjet Printer
Credit AIST
Superfine inkjet technology developed at AIST’s Nanotechnology Research Institute is being commercialized bySIJ Technology, Inc, an AIST spin-off company. The technology allows the ejection of super-fine liquid droplets smaller than the conventional droplets ejected by a home-use conventional inkjet printer. The revolutionary autonomous ink-jet method developed by Dr. K.Murata, NRI, AIST allows production and arrangements of dots with a minimum size of less than one micron, which corresponds to sub-femtoliter units in volume. This volume corresponds to a 1/1000 of the volume of the dots dispensed using the ink-jet devices currently on the market, which places this technology at the top of circuit printing technologies in the world
The super-fine inkjet technology developed by the Nanotechnology Research Institute of AIST allows the ejection of super-fine droplets much smaller than the conventional droplets ejected by a conventional inkjet printer-at least 1/10 smaller in size and 1/1000 smaller in volume.
Figure Comparison of Discharged Ink Drop Size
Credit: SIJ Technology Inc.
SIJ Technology, Inc. is engaged in the research and development with AIST and Harima Chemical to commericialize super-fine inkjet technology. Using this newly developed technology, the team has confirmed that diverse materials such as nanotubes, electroconductive polymers and ceramics can be used as solutes for the ink. At the same time, tests using NanoPaste®, stable dispersion of metal particles developed by Harima Chemicals, have been carried out, resulting in successful circuit printing on diverse substrates such as glass or polyimide. This result shows that it is possible to directly print ultrafine metallic wire of only a few microns in width.
Figure: Using NanoPaste® to Draw a Super-Fine Wiring Pattern
Credit: SIJ Technology Inc.
This technology can be applied not only to surface mounting related technologies but also to innovative applications in other nanotechnology fields such as biotechnology, optical and ultrafine processing technologies. Harima and AIST have filed U.S. Patent Application 20060286301 to protect NanoPaste® compositions and superfine inkjet technology.
To deepen the scope of the research, and to expand the range of applications in this field, AIST, SIJTechnology, Inc. and Harima are engaged in an ambitious joint research program that includes development of a range of metal nanoparticles for circuit printing.
An interesting aspect to metals is that for particles smaller than 20 nm in diameter, the effective melting point decreases dramatically. For example, the melting point of a super-fine silver particle may be as low as room temperature, whereas a micron sized particle of silver melts at 961ºC.
Using a solution with these nano-size particles as ink, with out novel printer, enables maskless patterning with a line width of several microns, which is comparable to the photolithographic methods, but at room temperature and normal atmospheric pressure.
Because super-fine liquid droplets dry very quickly, the droplets can be accumulated to form a three-dimensional structure by shooting them at a fixed target.
Figure: Forming a three-dimensional structure.
Credit SIJ Technology Inc.
Photo: Circuit boards and structures fabricated by super-fine inkjet
