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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Transformational Nano-confined Ionic Liquid Membrane for Greater than or Equal to 97 Percent Carbon Dioxide Capture from Natural Gas Combined Cycle Flue Gas

A transformational process based on nano-confined ionic liquid (NCIL) membranes was developed for capturing ≥97% CO 2 from natural gas combined cycle (NCCC) flue gas. The NCIL membranes were prepared by loading amino acid ionic liquid into a framework composed of single-walled carbon nanotube mesh filled with graphene oxide quantum dots. The membranes exhibited CO 2 permeance as high as 2,000 GPU with a CO 2 /N2 selectivity of 2,300 for a typical NGCC flue gas composition. When H 2 O vapor sweep was applied in the permeate side, 96.6% CO2 dry-basis purity and 97.6% CO 2 capture rate were achieved for a simulated NGCC flue gas with single stage. In the process design, a highly H 2 O-selective membrane would be needed to recover majority of the H 2 O vapor, and the recovered H 2 O vapor could be recycled to the permeate side of the NCIL membrane. Sulfonated poly(ether ether ketone) membranes were successfully developed for this purpose. These membranes exhibited H 2 O permeance great than 11,000 GPU and H 2 O/CO 2 selectivity greater than 1,000 at 70ºC for a feed mixture consisting of 14.5 vol% H2O and balanced CO 2 . A standalone membrane model using MATLAB platform was developed for process simulation. The model was validated with experimental data. Techno-economic analysis based on the testing data collected during the current program suggests this transformational membrane process can achieve 97% CO 2 capture efficiency with a cost of $47.8/tonne of CO 2 , which is a 21% reduction versus DOE’s reference case B31B.97.

03 NATURAL GAS↗
NASA NTRS1993

Squeezed states of electrons and transitions of the density of states

Electron systems which have low dimensional properties have been constructed by squeezing the motion in zero, one, or two-directions. An isolated quantum dot is modeled by a potential box with delta-profiled, penetrable potential walls embedded in a large outer box with infinitely high potential walls which represent the world function with respect to vacuum. We show the smooth crossover of the density of states from the three-dimensional to the quasi-zero dimensional electron gas.

Lee, Seung Joo↗
NASA NTRS1996

Design of intelligent mesoscale periodic array structures utilizing smart hydrogel

Mesoscale Periodic Array Structures (MPAS, also known as crystalline colloidal arrays), composed of aqueous or nonaqueous dispersions of self-assembled submicron colloidal spheres are emerging toward the development of advanced optical devices for technological applications. This is because of their unique optical diffraction properties and the ease with which these intriguing properties can be modulated experimentally. Moreover our recent advancements in this area which include 'locking' the liquid MPAS into solid or semisolid polymer matrices for greater stability with longer life span, and incorporation of CdS quantum dots and laser dyes into colloidal spheres to obtain nonlinear optical (NLO) responses further corroborate the use of MPAS in optical technology. Our long term goal is fabrication of all-optical and electro-optical devices such as spatial light modulators for optical signal processing and flat panel display devices by utilizing intelligent nonlinear periodic array structural materials. Here we show further progress in the design of novel linear MPAS which have the ability to sense and respond to an external source such as temperature. This is achieved by combining the self-assembly properties of polymer colloidal spheres and thermoshrinking properties of smart polymer gels. At selected temperatures the periodic array efficiently Bragg diffracts light and transmits most of the light at other temperatures. Hence these intelligent systems are of potential use as fixed notch filters optical switches or limiters to protect delicate optical sensors from high intensity laser radiation.

Sunkara, H. B.↗
NASA NTRS2001

NATO Advanced Study Institute on Spectroscopy

This booklet presents an account of the course 'Spectroscopy of Systems with Spatially Confined Structures' held in Erice-Sicily, Italy, from June 15 to June 30, 2001. This meeting was organized by the International School of Atomic and Molecular Spectroscopy of the 'Ettore Majorana' Centre for Scientific Culture. The purpose of this course was to present and discuss nanometer-scale physics, a rapidly progressing field. The top-down approach of semiconductor technology will soon meet the scales of the bottom-up approaches of supramolecular chemistry and of spatially localized excitations in ionic crystals. This course dealt with the fabrication, measurement and understanding of the relevant structures and brought together the scientific communities responsible for these development. The advances in this area of physics have already let to applications in optoelectronics and will likely lead to many more. The subjects of the course included spatially resolved structures such as quantum wells, quantum wires and quantum dots, single atoms and molecules, clusters, fractal systems, and the development of related techniques like near-field spectroscopy and confocal microscopy to study such systems.

DiBartolo, Baldassare↗
NASA NTRS2002

Modeling of Gate Bias Modulation in Carbon Nanotube Field-Effect-Transistors

The threshold voltages of a carbon nanotube (CNT) field-effect transistor (FET) are derived and compared with those of the metal oxide-semiconductor (MOS) FETs. The CNT channel is so thin that there is no voltage drop perpendicular to the gate electrode plane, which is the CNT diameter direction, and this makes the CNTFET characteristics quite different from those in MOSFETs. The relation between the voltage and the electrochemical potentials, and the mass action law for electrons and holes are examined in the context of CNTs, and it is shown that the familiar relations are still valid because of the macroscopic number of states available in the CNTs. This is in sharp contrast to the cases of quantum dots. Using these relations, we derive an inversion threshold voltage V(sub Ti) and an accumulation threshold voltage V(sub Ta) as a function of the Fermi level E(sub F) in the channel, where E(sub F) is a measure of channel doping. V(sub Ti) of the CNTFETs has a much stronger dependence than that of MOSFETs, while V(sub Ta)s of both CNTFETs and MOSFETs depend quite weakly on E(sub F) with the same functional form. This means the transition from normally-off mode to normally-on mode is much sharper in CNTFETs as the doping increases, and this property has to be taken into account in circuit design.

Yamada, Toshishige↗
NASA NTRS2002

Nanotube Sensors

Under this project, we explored the feasibility of utilizing carbon nanotubes in sensing applications. The grant primarily supported a graduate student, who worked on a number of aspects of the electrical properties of carbon nanotubes in collaboration with other researchers in my group. The two major research accomplishments are described below. The first accomplishment is the demonstration that solution carbon nanotube transistors functioned well in an electrolyte environment. This was important for two reasons. First, it allowed us to explore the ultimate limits of nanotube electronic performance by using the electrolyte as a highly effective gate, with a dielectric constant of approximately 80 and an effective insulator thickness of approximately 1 nm. Second, it showed that nanotubes function well under biologically relevant conditions (salty water) and therefore offer great promise as biological sensors. The second accomplishment was the demonstration that a voltage pulse applied to an AFM tip could be used to electrically cut carbon nanotubes. We also showed that a carefully applied pulse could also 'nick' a nanotube, creating a tunnel barrier without completely breaking the tube. Nicking was employed to make, for example, a quantum dot within a nanotube.

McEuen, Paul L.↗
NASA NTRS2002

Field-Sensitive Materials for Optical Applications

The purpose of investigation is to develop the fundamental materials and fabrication technology for field-controlled spectrally active optics that are essential for industry, NASA, and DOD (Department of Defense) applications such as: membrane optics, filters for LIDARs (Light Detection and Ranging), windows for sensors and probes, telescopes, spectroscopes, cameras, light valves, light switches, flat-panel displays, etc. The proposed idea is based on the quantum-dots (QD) array or thin-film of field-sensitive Stark and Zeeman materials and the bound excitonic state of organic crystals that will offer optical adaptability and reconfigurability. Major tasks are the development of concept demonstration article and test data of field-controlled spectrally smart active optics (FCSAO) for optical multi-functional capabilities on a selected spectral range.

Choi, Sang H.↗
NASA NTRS2003

Nanostructured Materials Development for Space Power

There have been many recent advances in the use of nanostructured materials for space power applications. In particular, the use of high purity single wall nanotubes holds promise for a variety of generation and storage devices including: thin film lithium ion batteries, microelectronic proton exchange membrane (PEM) fuel cells, polymeric thin film solar cells, and thermionic power supplies is presented. Semiconducting quantum dots alone and in conjunction with carbon nanotubes are also being investigated for possible use in high efficiency photovoltaic solar cells. This paper will review some of the work being done at RIT in conjunction with the NASA Glenn Research Center to utilize nanomaterials in space power devices.

Raffaelle, Ryne P.↗
NASA NTRS2003

Evolution of Local Microstructures of Clusters Undergoing 2-Dimensional Diffusion

A primary objective of our current work is to study the details of evolving microstructures through a study of "island" formation in heteroepitaxial film/substrate systems. Such systems could be of direct relevance to so-called mixed-dimensional coarsening and to the study of heterostructures grown by thin-film techniques. The spontaneous formation of three-dimensional islands in strained-layer heteroepitaxy, e.g., has emerged as a new technique for the synthesis of self-assembled quantum dots. This work focuses on coarsening by two-dimensional diffusion of three-dimensional droplets on a flat surface.

Frazier, Donald O.↗
NASA NTRS2003

Using Proteins to Build Nanocomputers

How low can we go? This is the question challenging scientists who want to build ever-smaller electronic components. As famed physicist Richard Feynmann said in 1959, 'there is plenty of room at the bottom,' meaning at the atomic or nanometric scale. But even Feynmann could only guess at how we might eventually build things 'down there.' As current lithographic techniques for etching semiconductor circuits rapidly approach their physical limits, scientists are looking for new and less expensive ways to fabricate circuits at infinitesimally small scales. NASA scientists have discovered a new tool that may help accomplish this goal - proteins. The basic building blocks of life may be harnessed to build computers and sensors on the nanoscale. Proteins provide self-assembling structures that can be engineered to build ordered arrays of quantum dots.

Laufenberg, Larry↗
NASA NTRS2004

Novel Biomedical Devices Utilizing Light-Emitting Nanostructures

As part of the NASA project, we are investigating the formation, properties, and performance of QD heterostructures, to be incorporated into a novel biomedical device for detecting bacteria and/or viruses in fluids on board space vehicles. We are presently synthesizing the epitaxial quantum dot structures using molecular beam epitaxy. We recently developed a method for controlling the arrangement of QDs, based upon a combination of buffer layer growth and controlled annealing sequences. This method is promising for producing arrangements of QDs with a locally well-controlled distribution of sizes. In the future, we plan to explore selective pre-patterning of the starting surface using focused ion-beam nanopatterning, which will enable us to precisely tune the compositions, sizes, and placement of the QDs, in order laterally tune the emission and detection wavelengths of QD based devices.

Goldman, Rachel S.↗
NASA NTRS2005

The Future of Bio-technology

Hosts of technologies, most notably in electronics, have been on the path of miniaturization for decades and in 2005 they have crossed the threshold of the nano-scale. Crossing the nano-scale threshold is a milestone in miniaturization, setting impressive new standards for component-packing densities. It also brings technology to a scale at which quantum effects and fault tolerance play significant roles and approaches the feasible physical limit form many conventional "top-down" manufacturing methods. I will suggest that the most formidable manufacturing problems in nanotechnology will be overcome and major breakthroughs will occur in a host of technologies, when nanotechnology converges with bio-technology; i.e. I will argue that the future of bio-technology is in nanotechnology. In 2005, methods in molecular biology, microscopy, bioinformatics, biochemistry, and genetic engineering have focused considerable attention on the nano-scale. On this scale, biology is a kind of recursive chemistry in which molecular recognition, self-assembly, self-organization and self-referencing context-control lead to the emergence of the complexity of structures and processes that are fundamental to all life forms. While we are still far from understanding this complexity, we are on the threshold of being able to use at least some of these biological properties for .technology. I will discuss the use of biomolecules, such as DNA, RNA, and proteins as "tools" for the bio-technologist of the future. More specifically, I will present in some detail an example of how we are using a genetically engineered 60-kDa protein (HSP60) from an organism living in near boiling sulfuric acid to build nano-scale templates for arranging metallic nanoparticles. These "extremophile" HSP60s self-assemble into robust double-ring structures called "chaperonins," which further assemble into filaments and arrays with nanometer accuracy. I will discuss our efforts to use chaperonins to organize quantum dots, electronic and magnetic nano-particles for electronic and photonic applications.

Trent, Jonathan↗
NASA NTRS2004

Thin Film Solar Cells: Organic, Inorganic and Hybrid

Thin film solar cells are an important developing resource for hundreds of applications including space travel. In addition to being more cost effective than traditional single crystal silicon cells, thin film multi-crystaline cells are plastic and light weight. The plasticity of the cells allows for whole solar panels to be rolled out from reams. Organic layers are being investigated in order to increase the efficiency of the cells to create an organic / inorganic hybrid cell. The main focus of the group is a thin film inorganic cell made with the absorber CuInS2. So far the group has been successful in creating the layer from a single-source precursor. They also use a unique method of film deposition called chemical vapor deposition for this. The general makeup of the cell is a molybdenum back contact with the CuInS2 layer, then CdS, ZnO and aluminum top contacts. While working cells have been produced, the efficiency so far has been low. Along with quantum dot fabrication the side project of this that is currently being studied is adding a polymer layer to increase efficiency. The polymer that we are using is P3OT (Poly(3-octylthiopene-2,5-diyll), retroregular). Before (and if) it is added to the cell, it must be understood in itself. To do this simple diodes are being constructed to begin to look at its behavior. The P3OT is spin coated onto indium tin oxide and silver or aluminum contacts are added. This method is being studied in order to find the optimal thickness of the layer as well as other important considerations that may later affect the composition of the finished solar cell. Because the sun is the most abundant renewable, energy source that we have, it is important to learn how to harness that energy and begin to move away from our other depleted non-renewable energy sources. While traditional silicon cells currently create electricity at relatively high efficiencies, they have drawbacks such as weight and rigidness that make them unattractive especially for space applications. Thin film photovoltaics have the potential to alleviate these problems and create a cheap and efficient way to harness the power of the sun.

Dankovich, John↗
NASA NTRS2004

Analysis of Electrical Characteristics of Thin Film Photovoltaic Cells

Solar energy is the most abundant form of energy in many terrestrial and extraterrestrial environments. Often in extraterrestrial environments sunlight is the only readily available form of energy. Thus the ability to efficiently harness solar energy is one of the ultimate goals in the design of space power systems. The essential component that converts solar energy into electrical energy in a solar energy based power system is the photovoltaic cell. Traditionally, photovoltaic cells are based on a single crystal silicon absorber. While silicon is a well understood technology and yields high efficiency, there are inherent disadvantages to using single crystal materials. The requirements of weight, large planar surfaces, and high manufacturing costs make large silicon cells prohibitively expensive for use in certain applications. Because of silicon s disadvantages, there is considerable ongoing research into alternative photovoltaic technologies. In particular, thin film photovoltaic technologies exhibit a promising future in space power systems. While they are less mature than silicon, the better radiation hardness, reduced weight, ease of manufacturing, low material cost, and the ability to use virtually any exposed surface as a substrate makes thin film technologies very attractive for space applications. The research group lead by Dr. Hepp has spent several years researching copper indium disulfide as an absorber material for use in thin film photovoltaic cells. While the group has succeeded in developing a single source precursor for CuInS2 as well as a unique method of aerosol assisted chemical vapor deposition, the resulting cells have not achieved adequate efficiencies. While efficiencies of 11 % have been demonstrated with CuInS2 based cells, the cells produced by this group have shown efficiencies of approximately 1 %. Thus, current research efforts are turning towards the analysis of the individual layers of these cells, as well as the junctions between them, to determine the cause of the poor yields. As a student of electrical engineering with some material science background, my role in this research is to develop techniques for analyzing the electrical characteristics of the CuInS2 cells. My first task was to design a shadow mask to be used to place molybdenum contacts under a layer of CuInS;! in order to analyze the contact resistance between the materials. In addition, I have also analyzed evaporated aluminum top contacts and have tested various methods of increasing their thicknesses in order to decrease series resistance. More recently I have worked with other members of the research group in reviving a vertical cold-wall reactor for experimentation with CuInS2 quantum dots. As part of that project, I have improved the design for a variable frequency and pulse width square wave generator to be used in driving the precursor injection process. My task throughout the remainder of my tenure is to continue to analyze and develop tools for the analysis of electrical properties of the CuInS2 cells with the ultimate goal of discovering ways to improve the efficiency of our photovoltaic cells. Traditionally, photovoltaic cells are based on a single crystal silicon absorber. While The research group lead by Dr. Hepp has spent several years researching copper indium

Kasick, Michael P.↗
NASA NTRS2005

Inorganic Photovoltaics Materials and Devices: Past, Present, and Future

This report describes recent aspects of advanced inorganic materials for photovoltaics or solar cell applications. Specific materials examined will be high-efficiency silicon, gallium arsenide and related materials, and thin-film materials, particularly amorphous silicon and (polycrystalline) copper indium selenide. Some of the advanced concepts discussed include multi-junction III-V (and thin-film) devices, utilization of nanotechnology, specifically quantum dots, low-temperature chemical processing, polymer substrates for lightweight and low-cost solar arrays, concentrator cells, and integrated power devices. While many of these technologies will eventually be used for utility and consumer applications, their genesis can be traced back to challenging problems related to power generation for aerospace and defense. Because this overview of inorganic materials is included in a monogram focused on organic photovoltaics, fundamental issues and metrics common to all solar cell devices (and arrays) will be addressed.

Hepp, Aloysius F.↗
NASA NTRS2006

Single-source precursors for ternary chalcopyrite materials, and methods of making and using the same

A single source precursor for depositing ternary I-III-VI.sub.2 chalcopyrite materials useful as semiconductors. The single source precursor has the I-III-VI.sub.2 stoichiometry built into a single precursor molecular structure which degrades on heating or pyrolysis to yield the desired I-III-VI.sub.2 ternary chalcopyrite. The single source precursors effectively degrade to yield the ternary chalcopyrite at low temperature, e.g. below 500.degree. C., and are useful to deposit thin film ternary chalcopyrite layers via a spray CVD technique. The ternary single source precursors according to the invention can be used to provide nanocrystallite structures useful as quantum dots. A method of making the ternary single source precursors is also provided.

Banger, Kulbinder K.↗