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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 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Localization of the Wannier–Mott Exciton on a Langmuir-Film/CdS Organic Semiconductor Interface

The low-temperature (T = 2 K) light reflectance spectra of organic semiconductor structures produced by depositing Langmuir–Blodgett films on a cadmium sulfide (CdS) crystal surface are studied. The spectra were studied in the region of the resonant frequency of the exciton state A{sub n} {sub = 1} in CdS. The spectra were analyzed within a multilayer medium model with allowance for the spatial dispersion and an exciton-free “dead” layer near the crystal surface contacting with the film. A conclusion is made that, as a result of the deposition of an organic film on a semiconductor crystal surface, the Wanier–Mott exciton is spatially localized near the film–crystal interface.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Quantitative study on the chemical solution deposition of zinc oxysulfide

Zinc Oxysulfide (ZnOS) has demonstrated potential in the last decade to replace CdS as a buffer layer material since it is a wide-band-gap semiconductor with performance advantages over CdS (E g = 2.4 eV) in the near UV-range for solar energy conversion. However, questions remain on the growth mechanisms of chemical bath deposited ZnOS. In this study, a detailed model is employed to calculate solubility diagrams that describe simple conditions for complex speciation control using only ammonium hydroxide without additional base. For these conditions, ZnOS is deposited via aqueous solution deposition on a quartz crystal microbalance in a continuous flow cell. Data is used to analyze the growth rate dependence on temperature and also to elucidate the effects of dimethylsulfoxide (DMSO) when used as a co-solvent. Activation energies (EA) of ZnOS are calculated for different flow rates and solution compositions. As a result, the measured EA relationships are affected by changes in the primary growth mechanism when DMSO is included.

14 SOLAR ENERGY↗
DOE OSTI2017

Asymmetric Semiconductor Nanorod/Oxide Nanoparticle Hybrid Materials: Model Nanomaterials for Light-Activated Formation of Fuels from Sunlight. Formal Progress Report -- Award DE-FG02-05ER15753

Executive Summary on Project Accomplishments: We focused our efforts for this project on the synthesis and characterization of semiconductor nanomaterials composed of semiconductor nanorods (NRs - e.g., CdSe, CdSe@CdS, CdS) with metal (Au, Pt, Co) or metal oxide (CoxOy) nanoparticle (NP) “tips.” These systems are attractive model systems where control of spatial, energetic and compositional features of both NRs and NP tips potentially enhances the efficiency of photogeneration and directional transport of charges, and photoelectrochemical conversion of sunlight to fuels. Synthetic methods to control material dimensions (20-200 nm in length), topology (one vs. two NP tips) and NR/NP tip compositions have been developed in the current project period (Pyun). We also achieved, for the first time in heterostructured nanorod materials, estimates of both valence band energies (E VB ) and conduction band energies (E CB ), using unique combinations of in vacuuo ultraviolet photoelectron spectroscopy (UPS, Armstrong), and waveguide spectroelectrochemistry (Saavedra), respectively. The spectroelectrochemical measurements in particular provide a unique path to estimation of E CB , and the distribution in E CB brought about by modification of NR composition. The combination of both approaches promises to be universally applicable to the characterization of energetics in nanomaterials of interest both for photovoltaic and sunlight-to-fuel photoelectrochemical assemblies.

14 SOLAR ENERGY↗
DOE OSTI2019

Manufacturing and Reliability Science for CIGS Photovoltaics

The purpose of this program was to overcome the largest challenges to investor confidence and long product lifetime in CuIn x Ga 1-x Se 2 (CIGS)-based photovoltaic products: metastability, shading-induced hot spots, and potential-induced degradation. Key findings were made in each of these areas by studying CIGS reliability at the cell level, which very few groups are currently doing. Metastability was thought to be a function of the CIGS absorber. We have challenged the state-of-the-art by showing that the metastability seen in commercial products is likely to be caused by the buffer layer. SCAPS device modeling confirmed that the buffer layer has a significant influence on metastability in CIGS devices, and also led to a processing change - the introduction of CdS islands to Zn(O,S) buffer layers - that dramatically reduced metastability in CIGS solar cells. In the reverse-bias shading task, modeling showed us that 19% solar cells are possible with thin CIGS layers of 0.5 µm. We were able to fabricate 15.2% solar cells in this project, which is the highest reported efficiency of devices in the ultra-thin class. We also discovered that the best way to dissipate less power in reverse bias was to eliminate the intrinsic ZnO layer that is often used in CIGS devices. Lower power dissipation led to devices that allowed two times the maximum power point current density in reverse without damage. Potential-induced degradation (PID) is caused by the drift of Na+ ions from the back glass to the CIGS/Mo interface, followed by diffusion into the solar cells and to the CdS region. We found that PID can be slowed by using low-conductivity borosilicate glass that contains higher K and lower Na than soda-lime glass. Based on significant progress in each of the three reliability challenges, the CIGS cell-level reliability project was very successful. We have also proved that module-level degradation mechanisms can be tested and solved at the cell level.

14 SOLAR ENERGY↗
DOE OSTI2022

Advanced Thin Film Core Technology: CIGS Final Technical Report (FTR)

Cu(In,Ga)Se 2 (CIGS) thin-film photovoltaics are a high-efficiency and reliable technology. This project completed research in two important areas and was designed to work collaboratively with industrial partners. Task 1: Alkali Science focused on alkali post-deposition treatments (PDT). PDTs have been instrumental in the dramatic voltage improvements that have moved CIGS device efficiencies from 20% to 23.35% [1]. Based on a survey of CIGS companies at the beginning of the project, the single biggest breakthrough for the CIGS community would be a mechanistic understanding of the role of alkalis in the material system. Significant accomplishments of Task 1: Alkali Science: 1) KF post-deposition treatments were shown to improve lifetime, open-circuit voltage (VOC), and efficiency of industrial partner samples, even when done as a later step, separate from the original CIGS deposition. 2) KF boosted efficiency when incorporated at the end of the third stage of NREL CIGS growth. 3) XPS characterization of CIGS surfaces with and without PDTs led to a proposed mechanism whereby K drives structural transformation at 350 degrees C that is locked in at room temperature even after K is rinsed away. 4) Published recipes for KF and RbF PDTs. Literature to date did not provide enough detail to quickly reproduce experimental results. 5) Identified most important parameters (RbF cell temperature and lamp setpoint temperature) and set boundaries for successful RbF PDTs. The purpose of Task 2: Cell-level Reliability was to overcome the largest challenges to investor confidence and long product lifetime in CIGS-based photovoltaic products: metastability, shading-induced hot spots, and potential-induced degradation (PID). Key findings were made in each of these areas by studying CIGS reliability at the cell level: 1) Published NREL's cell-level reliability testing procedures along with challenges that were encountered while developing them. These were also distributed to the community through an MRS conference presentation. 2) Decreased metastability by adding a CdS hole-injection layer between the CIGS and Zn(O,S) in the device stack. It also improved device performance. Materials other than CdS can be used for the same purpose. 3) Reduced front-glass PID by replacing soda-lime glass with low-Na borosilicate glass. 4) Found that PID depends on leakage current and light/electrical bias. This will help labs avoid test-specific degradation. 5) Discovered that CIGS can suffer from two different types of PID with different mechanisms. Front is slower and leads to shunting ZnO. Back is faster and degrades the p-n junction. 6) Holding cells at open circuit slows PID compared to short circuit. This affects testing protocols for glass/glass modules.

14 SOLAR ENERGY↗
DOE OSTI2022

Metal-Tipped and Electrochemically Wired Semiconductor Nanocrystals: Modular Constructs for Directed Charge Transfer

In our 2017 proposal to the Solar Photochemistry division of DOE/BES/Office of Science we targeted the creation, characterization and integratation of new II-IV semiconductor heterostructured nanomaterials into ultra-thin film (tethered) nanocrystalline arrays on transparent metal oxide (TCO) supports. Materials were to include CdSe quantum dots (QDs), asymmetric CdSe@CdS tetrapods (TPs) and CdSe@CdS nanorods (NRs), into unique photoelectrochemical platforms. The ultimate goal was to tether these new nanomaterials to either electron- or hole-selective oxide interlayers that would afford vectoral photo-induced charge transfer and ultimately formation of molecular products such as H 2 . This was an ambitious set of goals but integrated well with our previous work in this general area.

14 SOLAR ENERGY↗
DOE OSTI2023

PIPII cryoplant non thermal cycling updates

The Proton Improvement Plan-II (PIP-II) is a crucial upgrade to the Fermilab accelerator complex, featuring a new 800-MeV Superconducting Radio-Frequency (SRF) linear accelerator (LINAC) with 23 cryomodules operating at 2K. The LINAC thermohydraulic conditions are satisfied by the cryogenic subsystems: Cryogenic Distribution System (CDS), a helium refrigerator cold box (CB), a warm compression station (WCS) and a helium recovery system (RSYS). The accelerator has a strict requirement of non-thermal cycling of the LINAC cryomodules during planned and unplanned subsystem outages. This paper presents an integrated operating modes analysis of the of the LINAC/CDS thermohydraulic loads satisfied by the CB/WCS cooling system supported by the RSYS inventory management system. The study is based on latest cryoplant and CDS engineering deliverables, as well as the recent performance data from single cryomodule qualification tests performed at the Fermilab PIP-II Injector Test test s tand. The study evaluates both normal and abnormal operating modes, with a focus on identifying integrated scenarios that put subsystems components under stress. The conclusions of this study will help build redundancy to reduce the risk of thermal cycles during planned and unplanned subsystem outages.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Design and Analysis of 10” Parallel Plate Relief Device

All Cryomodule (CM) and Cryogenic Distribution System (CDS) relieving into Helium Low Pressure (LP) return header, which is connected to compressor suction so, helium can be preserved during small flow relieving event and recirculated to system. However, during worst case scenario, Helium LP header requires a parallel plate relief device to relieve excess pressure from header. To complete the CDS Warm piping header, a new design for a 10 parallel plate relief device is necessary to relieve outside of the tunnel into atmosphere.

Chicas, Kelly↗
DOE OSTI2025

Alaska Liquid Natural Gas Pipeline Front-End Engineering & Design (Final Technical Report)

The Alaska Gasline Development Corporation (AGDC) is Alaska’s natural gas infrastructure development corporation established in 2013. AGDC’s mission is to maximize the benefit of Alaska’s vast North Slope natural gas resources for Alaskans through the development of infrastructure necessary to move the gas into local and international markets. AGDC was identified for a Congressionally Directed Spending (CDS) project for funding in the Energy and Water Development and Related Agencies Appropriations Act, 2023 under the heading: “Congressionally Directed Energy Efficiency and Renewable Energy Projects.” The CDS included $\$$4,000,000 of direct funding, with required match funds, to move the project forward. Alaska’s North Slope holds America’s largest proven and conventional natural gas supply. The integrated Alaska LNG Project will deliver 3.5 billion cubic feet of natural gas per day from Alaska’s North Slope gas fields to Alaskans as well as to a marine terminal located at tidewater in Cook Inlet. Alaska LNG is an integrated gas infrastructure project with three major components: a gas treatment plant (GTP) located at Prudhoe Bay, an 807-mile (1,287 km) gas pipeline (Mainline Pipeline) to Southcentral Alaska with interconnections for in-state gas use, and a natural gas liquefaction facility (LNG Facility) in Nikiski, Alaska. The integrated Alaska LNG Project has several strategic advantages including proven gas resources, existing upstream infrastructure, an advantageous arctic climate for LNG production, proximity to LNG markets, a track record of reliability from a state that first began exporting LNG to Japan in 1969, and broad support from Alaskans. North Slope natural gas is a conventional resource and can be produced with minimal drilling at a fraction of the carbon dioxide emissions of shale gas from the Lower 48 states. Through the development of the Alaska LNG Project, Alaska can provide energy security to Alaskans and a stable source of LNG to the Asia-Pacific region for generations. The Alaska LNG Project has been progressed through Pre-Front-End Engineering Design (Pre-FEED) and has obtained all major federal and State of Alaska permits and authorizations to construct the project, including the Federal Energy Regulatory Commission (FERC) Order Granting Authorization Under Section 3 of the Natural Gas Act. On September 5, 2024, the U.S. Department of Energy (DOE), National Energy Technology Laboratory (NETL) awarded Project No. DE-FE0032307 to AGDC with the objective to progress the project to Front-End Engineering Design (FEED) entry for the Alaska LNG Project Phase 1 Pipeline. The award Start Date was made effective July 1, 2023, with a Period of Performance through June 30, 2025. On March 27, 2025, AGDC announced the execution of definitive commercial agreements with Glenfarne Alaska LNG, LLC, an affiliate of Glenfarne Group, LLC, (together as “Glenfarne”), to lead the development of the Alaska LNG Project and enter FEED for the Phase 1 Pipeline. Project activities are now funded and directed by this private sector partner who holds a 75% interest in 8 Star Alaska, LLC (8 Star). 8 Star holds the assets of the Alaska LNG Project. As planned, AGDC continues to hold 25% minority interest in 8 Star and will play a governance role moving forward with Alaska LNG. This definitive commercial agreement milestone led to the successful completion of AGDC’s Statement of Project Objectives (SOPO) for FEED entry and led to the completion of DOE Project No. DE-FE0032307. At conclusion of the SOPO, AGDC also reached the award’s maximum federal cost share of $\$$4,000,000. AGDC is, therefore, providing Final Technical Report to close out DOE Project No. DE-FE0032307.

02 PETROLEUM↗
DOE OSTI2025

Uncertainty quantification and sensitivity analysis of a nuclear thermal propulsion reactor startup sequence

The research presented in this article describes progress in applying stochastic methods, uncertainty quantification, parametric studies, and variance-based sensitivity analysis (also known as Sobol sensitivity analysis) to a full-core model of a nuclear thermal propulsion (NTP) system simulated via the radiation transport code Griffin to simulate neutronics. Our goal is to develop a reduced-order (surrogate) model that can be rapidly sampled with perturbations to multiple input parameters. In this NTP system, reactivity and power feedback affect the rotation of control drums (CDs), which is itself controlled by a hybrid proportional-integral-derivative (PID) controller actuated by the power demand and reactivity feedback from the numerical model. This model uses reactor kinetic feedback (mean generation time [Λ] and effective delayed neutron fraction [ β eff ] from a transient Griffin simulation executed via Griffin’s improved quasi-static solver to provide the kinetic parameters) as inputs to functions that control the CD rotation angle. By investigating numerous stochastic approaches, we developed a dual-purpose surrogate model of the NTP system, using polynomial regression in the Multiphysics Object-Oriented Simulation Environment (MOOSE) Stochastic Tools Module (STM). The trained model can be rapidly sampled while simultaneously perturbing various input parameters, such as coefficients on the PID control or temperature (directly affecting the neutron cross section). The surrogate model delivers accurate (within 5%) results at speeds orders of magnitude faster (minutes, not days of computational time) than the base model. Once the surrogate model has been trained, distributions of the uncertain parameters can be changed at will to investigate the effects of perturbing multiple inputs as well as the effects of these inputs on the model output. For example, coefficients used in the PID control system may vary due to some type of physical interference, or uncertainty may exist in the temperature of the neutron cross sections in various regions of the reactor. A distribution can be placed on these parameters, and operational boundaries can be determined. The goal of this work is to support development of an advanced control system for operating CDs in a functioning NTP system. This work is a scoping study of the MOOSE STM.

21 - SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLAN↗
DOE OSTI2020

Preparation and Characterization of Inclusion Complexes of β-Cyclodextrin and Phenolics from Wheat Bran by Combination of Experimental and Computational Techniques

Bitterness often associated with whole wheat products may be related to phenolics in the bran. Cyclodextrins (CDs) are known to form inclusion complexes. The objective was to form inclusion complexes between β-CD and wheat phenolics. Pure phenolic acids (trans-ferulic acid (FA), caffeic acid (CA), and p-coumaric acid (CO)) and phenolic acids from wheat bran were used to investigate complex formation potential. Complexes were characterized by spectroscopy techniques, and a computational and molecular modeling study was carried out. The relative amount of complex formation between β-CD and wheat bran extract was CA > CO > FA. The phenolic compounds formed inclusion complexes with β-CDs by non-covalent bonds. The quantum-mechanical calculations supported the experimental results. The most stable complex was CO/β-CD complex. The ΔH value for CO/β-CD complex was -11.72 kcal/mol and was about 3 kcal/mol more stable than the other complexes. The QSPR model showed good correlation between binding energy and 1H NMR shift for the H5 signal. This research shows that phenolics and β-CD inclusion complexes could be utilized to improve the perception of whole meal food products since inclusion complexes have the potential to mask the bitter flavor and enhance the stability of the phenolics in wheat bran.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2013

Seeded Synthesis of CdSe/CdS Rod and Tetrapod Nanocrystals

Here, we demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded synthesis strategy is used in which spherical seeds of CdSe are prepared first using a hot-injection technique. By controlling the crystal structure of the seed to be either wurtzite or zinc-blende, the subsequent hot-injection growth of CdS off of the seed results in either a rod-shaped or tetrapod-shaped nanocrystal, respectively. The phase and morphology of the synthesized nanocrystals are confirmed using Xray diffraction and transmission electron microscopy, demonstrating that the nanocrystals are phase-pure and have a consistent morphology. The extinction coefficient and quantum yield of the synthesized nanocrystals are calculated using UV-Vis absorption spectroscopy and photoluminescence spectroscopy. The rods and tetrapods exhibit extinction coefficients and quantum yields that are higher than that of the bare seeds. This synthesis demonstrates the precise arrangement of materials that can be achieved at the nanoscale by using a seeded synthetic approach.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Nucleotide sequence

Saccharomyces kudriavzevii isolate AH052 alpha-1,2-mannosyltransferase MNN2 (MNN2) and Transportin (KAP104) genes, complete cds; GAL7, GAL10, and GAL1 pseudogenes, complete sequence; and Plasma membrane localized uracil permease (FUR4), Phosphatase Of ADP-ribose 1'-phosphate (POA1), and chitin synthase CHS3 (CHS3) genes, complete cds

Genetics↗
NASA NTRS1973

Ultrasonic signal enhancement by resonator techniques

Ultrasonic resonators increase experimental sensitivity to acoustic dispersion and changes in attenuation. Experimental sensitivity enhancement line shapes are presented which were obtained by modulating the acoustic properties of a CdS resonator with a light beam. Small changes in light level are made to produce almost pure absorptive or dispersive changes in the resonator signal. This effect is due to the coupling of the ultrasonic wave to the CdS conductivity which is proportional to incident light intensity. The resonator conductivity is adjusted in this manner to obtain both dispersive and absorptive sensitivity enhancement line shapes. The data presented verify previous thoretical calculations based on a propagating wave model.

Heyman, J. S.↗
NASA NTRS1975

Reactively sputtered thin film photovoltaic devices

The feasibility of a reactively sputtered thin film CdS - Cu2S solar cell is proven. Identification of the reactively sputtered Cu2S film is made by X-ray diffractometer and spectro-transmission measurements. Because of its simplicity, economical use of material, and high yield, the reactive sputtering process promises to be a low cost method for producing CdS - Cu2S solar cells.

Hsieh, E. J.↗
NASA NTRS1975

Applied research on 2-6 compound materials for heterojunction solar cells

Several II-VI heterojunctions show promise for photovoltaic conversion of solar energy. The three of greatest interest are p-CdTe/n-CdS, p-CdTe/n-ZnSe, and p-ZnTe/n-CdSe. Several p-CdTe/n-CdS heterojunction cells have been prepared by close spaced transport deposition of p-CdTe on single crystal n-CdS, and by two source vacuum evaporation of n-CdS on single crystal p-CdTe. Both types of cells, in an experimental stage, are quite comparable, exhibiting values of quantum efficiency between 0.5 and 0.9, open circuit voltages between 0.50 and 0.66 V, fill factors between 0.4 and 0.6, and solar efficiencies up to 4 percent. Cells of p-ZnTe/n-CdSe have also been made by close spaced vapor transport deposition of n-CdSe on single crystal p-ZnTe.

Bube, R. H.↗
NASA NTRS1980

Internal electrostatic discharge hazard risk assessment to the Galileo orbiter

A worst case assessment was performed on the Command Data System (CDS) multilayer printed circuit board and an output power transformer module in the power subsystem. An estimate of the Jovian environment during the 35 hour orbit insertion was supplied by JPL and used as an input to calculate the electron transport into the Galileo components. A radiation shielding analysis computer code, CHARGE, calculated the electron transport deposition trapped in the anticipated sensitive areas of the multilayer board and transformer module. Based on these trapped charge calculations electric fields were calculated between the identified isolated areas and the spacecraft ground. The results of the assessment of electrostatic discharge (DSD) in the CDS multilayer printed circuit board indicate that the probability of ESD in the FR4 is low. The probability of ESD in the components attached to the multilayer board, however, is uncertain based on a lack of prior experimental data.

Schmidt, R. E.↗