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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 1,657 records · Page 92
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Characterization of FeCl 3 Intercalation Doped CVD Few-Layer Graphene

Historically, intercalation doping has been theoretically and experimentally studied on Chemical Vapor Deposition (CVD) synthesized few-layer graphene. Density Functional Theory calculations identified FeCl 3 as a good dopant to reduce the sheet resistance of few-layer graphene. A simple vapor transfer approach is employed to dope graphene. The successful doping is confirmed by the Raman spectra as well as electrical measurements. After doping, graphene shows p-type conducting behavior and its conductance is significantly enhanced compared with that of undoped graphene. 3-layer graphene exhibited a sheet resistance of 40 Ω/$\square$, while 4-layer graphene has even smaller sheet resistance of 20 Ω/$\square$, with transmittance ≥ 90% for both cases. which offer the best combination of sheet resistance and transmittance among all previously reported transparent conductors.

42 ENGINEERING↗
DOE OSTI2016

Interfacial Modifiers for Enhanced Stability and Reduced Degradation of Cu(In,Ga)Se2 Devices

Transparent conductive oxide (TCO) degradation is a known failure mode in thin-film photovoltaic (PV) devices through mechanisms such as resistivity increase and delamination. Here we apply thin interfacial modifiers to aluminum-doped zinc oxide (AZO) to mitigate damp heat induced degradation of electrical performance. Additionally, we demonstrate that these modifiers can be applied to the AZO front contact of a Cu(In, Ga)Se2 device without significantly degrading the device performance, a promising step towards improving the lifetime performance.

14 SOLAR ENERGY↗
DOE OSTI2018

Impact of Infrared Optical Properties on Crystalline Si and Thin Film CdTe Solar Cells

Photons with energies below the photovoltaic (PV) absorber band gap do not generate current and adversely impact performance when absorbed in other solar cell components to produce heat. Here we incorporate infrared (IR) optical response in simulations for understanding thermal losses. Spectroscopic ellipsometry is used to measure Al-Si interface optical properties in Si PV. Reflectance of an Si module has been analyzed to account for encapsulant and Al-Si interface contributions. IR extended quantum efficiency simulations calculate efficiency gains / losses arising from variations in current generated and total reflectance as functions of transparent front contact material in thin film CdTe PV.

14 SOLAR ENERGY↗
DOE OSTI2014

Spectroelectrochemical Sensors: New Polymer Films for Improved Sensitivity

The selectivity of an optical sensor can be improved by combining optical detection with electrochemical oxidation or reduction of the target analyte to change its spectral properties. The changing signal can distinguish the analyte from interferences with similar spectral properties that would otherwise interfere. The analyte is detected by measuring the intensity of the electrochemically modulated signal. In one form this spectroelectrochemical sensor consists of an optically transparent electrode (OTE) coated with a film that preconcentrates the target analyte. The OTE functions as an optical waveguide for attenuated total reflectance (ATR) spectroscopy, which detects the analyte by absorption. Sensitivity relies in part on a large change in molar absorptivity between the two oxidation states used for electrochemical modulation of the optical signal. A critical part of the sensor is the ion selective film. It should preconcentrate the analyte and exclude some interferences. At the same time the film must not interfere with the electrochemistry or the optical detection. Therefore, since the debut of the sensor’s concept one major focus of our group has been developing appropriate films for different analytes. Here we report the development of a series of quaternized poly(vinylpyridine)-co-styrene (QPVP-co-S) anion exchange films for use in spectroelectrochemical sensors to enable sensitive detection of target anionic analytes in complex samples. The films were either 10% or 20% styrene and were prepared with varying degrees of quaternized pyridine groups, up to 70%. Films were characterized with respect to thickness with spectroscopic ellipsometry, degree of quaternization with FTIR, and electrochemically and spectroelectrochemically using the anions ferrocyanide and pertechnetate.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2019

Investigating the Effect of Lamination on FAMACs: Toward a New Phase Space of Perovskite Solar Cell Fabrication

The rapid progress in the field of perovskite solar cells has led to efficiencies approaching that of crystalline silicon in single junction devices, and increasing emphasis is now being placed on scalable fabrication strategies that have the potential to truly impact the photovoltaics industry. The standard fabrication route of sequential, layer-bylayer depositions to form the device stack is limited by the small range of selective materials that can withstand successive solvent exposures and thermal annealings. In order to overcome this limitation, we have developed a method to fabricate the device stacks through mechanical lamination under moderate pressures and temperatures. The procedure involves fabricating two transparent conductive oxide/transport material/perovskite half stacks and laminating them together at the perovskite/perovskite interface. This procedure previously achieved 10% efficiency in initial attempts based on methyl ammonium lead iodide (MAPI) perovskite compositions. Herein, we reported the fabrication conditions to achieve a reproducible lamination with a complex, multi-cation perovskite, [Cs0.05(MA0.17F A0.83)0.95P b(I0.83Br0.17)3] (FAMACs), laminated at 18 degrees C and with a pressure of 350 psi for 30 minutes. The resulting material showed a sharpening of the optical absorption edge and a slight reduction in the band gap from 1.622 eV to 1.616 eV, indicative of improved ordering and reduced defects. Concurrently, time resolved photoluminescence measurements revealed an increased luminescence lifetime from 85 ns to 123 ns.

14 SOLAR ENERGY↗
DOE OSTI2024

Color symmetry and confinement as an underlying superconformal structure in holographic QCD

Dedicated to the memory of our colleague, Harald Fritzsch, who, together with Murray Gell-Mann, introduced the color quantum number as the exact symmetry responsible for the strong interaction, thus establishing quantum chromodynamics (QCD) as a fundamental non-Abelian gauge theory. A basic understanding of hadron properties, however, such as confinement and the emergence of a mass scale, from first principles QCD has remained elusive: Hadronic characteristics are not explicit properties of the QCD Lagrangian and perturbative QCD, so successful in the large transverse momentum domain, is not applicable at large distances. In this article, we shall examine how this daunting obstacle is overcome in holographic QCD with the introduction of a superconformal symmetry in anti de Sitter (AdS) space which is responsible for confinement and the introduction of a mass scale within the superconformal group. When mapped to light-front coordinates in physical spacetime, this approach incorporates supersymmetric relations between the Regge trajectories of meson, baryon and tetraquark states which can be visualized in terms of specific SU(3) C color representations of quarks. Finally, we will also briefly discuss here the implications of holographic models for QCD color transparency in view of the present experimental interest.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Conducting more inclusive solar geoengineering research: A feminist science framework

Solar geoengineering, or deliberate climate modification, has been receiving increased attention in recent years. Given the far-reaching consequences of any potential solar geoengineering deployments, it is prudent to identify inherent biases, blind spots, and other potential issues at all stages of the research process. Here we articulate a feminist science-based framework to concretely describe how solar geoengineering researchers can be more inclusive of different perspectives and potentially contradictory conclusions, in the process illuminating potential implicit bias and enhancing the conclusions that can be gained from their studies. Importantly, this framework is an adoptable method of practice that can be refined, with the aim of conducting better research in solar geoengineering. As an illustration, we retrospectively apply this framework to a well-read solar geoengineering study (also led by the first author of this study), improving transparency by revealing its implicit values, conclusions made from its evidence base, and the methodologies that study pursues. We conclude here with a set of recommendations for the geoengineering research community whereby more inclusive research can become a regular part of practice. Throughout this process, we illustrate how feminist science scholars can use this approach to study climate modeling.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Improvement of screen-printable metallization paste for low-cost silicon solar cells utilizing silver coated copper powders

This aims of this project were to develop low-cost screen-printable Ag|Cu metallization, as alternative to Ag paste, for contacting PERC solar cells with transparent emitter for high performance and reliability. The intended goal was to achieve 81% fill factor with a screen-printable Ag|Cu paste alternative. This was attempted through a three strand approach including Ag|Cu formulation by SVMT, production using cavitation technology by ACI and contact formation through the understanding of (i) the liquid phase sintering of the nano/macro particles of Ag|Cu to achieve bulk metal with very low series resistance, (ii) optimization of contact firing to avoid penetration of Cu into the silicon bulk, and finally (iii) proper analysis to quantify the contributions of each resistance component and keep the total series resistance at 0.2 Ω-cm2, which would result in high fill factor of 81% by UNC Charlotte. The objectives also involved i) the implementation of glass frit with Cu metal that will etch through the ARC for low contact resistance and adhesion, ii) development of Ag|Cu pastes with the optimized glass frit, iii) investigation of the impact of Cu particle size, morphology and loading on the gridline resistance, iv) narrow gridline screen designs along with narrow gridline prints, v) development of fast belt speeds of up to 375 inches per minute (ipm) sintering, and vi) stability study on Ag|Cu contact to high performance and reliability.

14 SOLAR ENERGY↗
DOE OSTI2026

Open-Air Manufacturing of Efficient Large-Area Perovskite Solar Cells to Meet Stability and Cost Targets

This SETO-funded project (DE-EE0009516) developed a fully open-air manufacturing pathway for perovskite solar cells and modules, eliminating vacuum-based processing steps while improving device stability. Open-air ultrasonic spray deposition, solution combustion synthesis, rapid thermal processing, and atmospheric plasma curing were developed and optimized for all functional device layers — perovskite absorber, hole transport layers (HTLs), electron transport layers (ETLs), transparent conducting oxides (TCOs), and rear electrodes — without reliance on vacuum. Sprayed organic ETLs preserved perovskite crystal structure and enabled power conversion efficiencies exceeding 20%, and open-air processed TCOs and rear electrodes achieved optoelectronic performance comparable to sputtered alternatives at substantially lower manufacturing cost. Device stability was assessed through accelerated aging protocols aligned with IEC and ISOS standards, combined with high-throughput optical diagnostics that identified key degradation mechanisms and antagonistic interactions among heat, humidity, and illumination stressors. A comprehensive technoeconomic analysis quantified the cost and throughput advantages of open-air manufacturing over conventional vacuum-based processes, identifying vacuum deposition as the dominant cost driver and demonstrating a clear pathway toward the $0.02/kWh target. The project produced five peer-reviewed journal publications, eleven conference presentations, two patents/applications, and five Ph.D. dissertations.

14 SOLAR ENERGY↗
DOE OSTI2021

Adaptive Cognitive Mechanisms to Maintain Calibrated Trust and Reliance in Automation

Trust calibration for a human–machine team is the process by which a human adjusts their expectations of the automation’s reliability and trustworthiness; adaptive support for trust calibration is needed to engender appropriate reliance on automation. Herein, we leverage an instance-based learning ACT-R cognitive model of decisions to obtain and rely on an automated assistant for visual search in a UAV interface. This cognitive model matches well with the human predictive power statistics measuring reliance decisions; we obtain from the model an internal estimate of automation reliability that mirrors human subjective ratings. The model is able to predict the effect of various potential disruptions, such as environmental changes or particular classes of adversarial intrusions on human trust in automation. Finally, we consider the use of model predictions to improve automation transparency that account for human cognitive biases in order to optimize the bidirectional interaction between human and machine through supporting trust calibration. The implications of our findings for the design of reliable and trustworthy automation are discussed.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2026

Data Associated with "Identifying Suitable Front Contacts for High-Efficiency Cd(Se,Te) Solar Cells on Space-Qualified Cover Glass"

This is data associated with the publication " Identifying Suitable Front Contacts for High-Efficiency Cd(Se,Te) Solar Cells on Space-Qualified Cover Glass " by Aesha P. Patel, Ryan Muzzio, Matthew R. Young, Robert Morrissey, Suresh Chaulagain, B. Edward Sartor, Prabodika N. Kaluarachchi, Christian Velez, Joshua A. Brown, Joel N. Duenow, Stephen Glynn, Michael J. Heben, Zhaoning Song, Nikolas J. Podraza, Adam B. Phillips, Randy J. Ellingson, Matthew O. Reese. All data associated with each figure in the manuscript and supplementary should be available in this dataset. A readme file is also included to provide some guidance. Abstract: Deployment of photovoltaics in space requires devices that combine high-efficiency, low areal mass, and resilience to harsh environments. Historically, high-efficiency multijunction III–V materials have dominated space power systems; however, their high cost and limited manufacturing throughput motivate the exploration of scalable alternatives. While CdTe-based thin-film photovoltaics offer an attractive option, their performance on non-conventional substrates can suffer from front-contact instability under higher-temperature processing. Here, the role of front-contact chemistry in limiting cell performance is investigated using CdTe-based devices fabricated on 150 μm thick Ceria-doped space-qualified 0214 Corning glass. A matrix of four transparent conducting oxides (TCOs: CTO, AZO, ITO, IZO) combined with two n-type emitters (MZO, IGO) reveals chemical stability at the front interface—rather than absorber composition alone—governs recombination losses, voltage deficits, and device reproducibility. Chemically stable front-contact combinations suppress elemental diffusion and interfacial degradation, resulting in significantly improved carrier lifetimes and junction quality. These insights are validated through record-certified Cd(Se,Te) cell efficiencies of 18.4% under AM1.5G and 16.2% under AM0 illumination on ultra-thin glass. Beyond CdTe, this work provides a general framework for the rational selection of TCO/emitter interfaces in superstrate thin-film photovoltaics, including emerging technologies like metal halide perovskites, while enabling high-efficiency, lightweight photovoltaics for space applications.

14 SOLAR ENERGY↗
NASA NTRS2003

Opto-electronic oscillator stabilized by hyperfine atomic transition

We have built an opto-electronic oscillator (OEO) with a frequency filter implemented by electromagnetically induced transparency (EIT). This internal fundamental frequency reference corresponding to the hyperfine splitting in 87Rb allows for efficient stabilization of the oscillator.

opto-electronic↗
NASA NTRS2021

NASA Framework for the Ethical Use of Artificial Intelligence (AI)

The NASA Framework for the Ethical Use of Artificial Intelligence (AI) provides six key principles to guide NASA's use of AI. The principles are NASA's AI must be 1. Fair, 2., Explainable and transparent, 3. Accountable, 4. Secure and safe, 5. Human-centric and societally beneficial, and 6. Scientifically and technically robust. The framework describes each ethical AI principle, and then applies that principle to NASA work. The framework also includes a list of questions practitioners should use to guide their AI work. Finally, the framework focuses on concrete, practical considerations for the next five - ten years, while also beginning to lay the foundation for longer-term disruptive change as human-level (or beyond) AI is created.

Artificial Intelligence↗
NASA NTRS2022

NASA's Responsible AI Plan

Artificial Intelligence (AI) is an integral part of today’s process of conducting science and technology development. At NASA, AI has become an integral and important tool for researchers, engineers, data scientists, and technologists in pursuing the ground-breaking discoveries that we are known for, including the command and controlling of our spacecraft and other supporting infrastructures. Consequently, research and engineering efforts incorporating AI have permeated almost every area of our work. It is contributing to NASA’s drive toward the future, not just of space science, but for society here at home. We are dedicated to continuing the use of AI in a safe and fully transparent approach so that the public can have high confidence in the outcomes and benefits. We believe that the plan outlined here will be responsive and contribute to the call for openness across the federal government. NASA is committed to responsible use of AI in all of its activities and in all phases of development and deployment of its space and terrestrial programs missions. NASA does not deliberately focus on “AI Research” as a separate field (we have no single “AI office” or “AI program”), rather NASA uses AI to build tools for its programs. This plan, being put forward, adheres to the Responsible AI (RAI) principles set and laid down by the White House in its Presidential Executive Order 13960. Our research, engineering and technical communities have been made aware of these guidelines and we are committed to an on-going process of educating and monitoring its implementation to ensure adherence to those principles. The vast majority of NASA’s use cases, which number almost 75 today, are geared toward analyzing the petabytes of data that NASA collects from its fleet of spacecraft across all disciplines, in human space exploration, and in aeronautics, etc.

Artificial Intelligence↗