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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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72 records · Page 4

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DOE OSTI2020

Enhanced intersystem crossing of boron dipyrromethene by TEMPO radical

Radical enhanced intersystem crossing (EISC) of organic chromophores is an important approach to generate a long-lived triplet state for various electronic and optoelectronic applications. However, structural factors and design rules to promote EISC are not entirely clear. In this work, we report a series of boron dipyrromethene (BODIPY) derivatives covalently linked with a 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO) radical with varying distances and topologies. We show that the incorporation of the TEMPO radical to BODIPY results in strong fluorescence quenching by up to 85% as a result of EISC and enhanced internal conversion. In BDP-2AR [2-(4-methyleneamino-TEMPO) BODIPY], a dyad with the shortest BODIPY–TEMPO through-bond distance, we observe the fastest EISC rate (τ isc = 1.4 ns) and the longest triplet excited state lifetime (τ T = 32 μs) compared to other distance and geometry variations. Contrary to previous reports and a general presumption, the BODIPY–TEMPO through-bond distance in this system does not play a significant role on the triplet formation rate and yield. Finally, density functional theory suggests a folding of the TEMPO radical to form a sandwich-like structure with a BODIPY ring that leads to a decrease in the through-space distance, providing a new and an interesting insight for the radical enhanced intersystem.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2019

Field-Aged Glass/Backsheet and Glass/Glass PV Modules: Encapsulant Degradation Comparison

Ethylene vinyl acetate (EVA) is the predominant encapsulant in crystalline-silicon photovoltaic (PV) modules; however, its degradation is a subject of major concern, which causes significant power loss under field conditions. This article presents a comparison of EVA degradation in field-aged PV modules with glass/backsheet (G/B) and glass/glass (G/G) architectures. Modulelevel characterization included UV fluorescence imaging and I-V measurements. Material analytical techniques, including colorimetry, differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, and Raman spectroscopy, were performed to correlate the module performance parameters with EVA material properties. An intense EVA discoloration in G/G modules was observed, which was corroborated by higher module Isc and Pmax degradation rates compared with its counterpart G/B modules. Higher power degradation was accompanied by a significant increase in EVA crosslinking, vinyl acetate content, yellowness index, and presence of functional groups containing unsaturated moieties that are linked to degradation products of photothermal reaction, and a higher decrease in the degree of crystallinity. The absence of a polymeric backsheet in hermetically sealed G/G modules, which restricts photobleaching and enhances the entrapment of volatile acetic acid and other degradation by-products, plays a major role in causing higher EVA degradation in G/G modules. This article concludes that EVA might have been a good choice of an encapsulant for the G/B modules over the decades, but it may prove to be an inappropriate choice for the G/G modules because of potential degassing, corrosion, and/or discoloration issues. Ionomers or polyester-based encapsulants like polyolefins could be best suited for G/G modules as it appears to be a current trend in the industry.

14 SOLAR ENERGY↗

DOE OSTI2023

Impact of Irradiation-Induced Filter Heating on Calibration of NIR-Longpass-Filtered Reference Solar Cells

Reference solar cells play a crucial role in determining the performance of photovoltaic (PV) devices. In the performance calibration chain of mainstream single-junction PV technologies, common reference cell types include Si, KG-filtered Si, and GaAs cells. For emerging multijunction (MJ) PV technologies, such as CdTe/Si and perovskite/Si, Si reference cells with colored glass near-infrared-longpass (LP) filters like Schott RG-715 and 850 glass have been proposed. They offer a better spectral response that matches the bottom junctions of the emerging MJs, which could lead to lower uncertainties in performance measurements. However, this article reveals a prominent decrease in short-circuit current (ISC) during National Renewable Energy Laboratory's primary calibration over the course of minutes when using this type of LP-filtered reference cell, which could result in unacceptable measurement errors. Unlike quartz or KG filter glasses, LP colored glass filters demonstrate temperature-sensitive cut-on wavelength. When incident irradiance reaches these LP-filtered reference cells, the increased temperature due to light absorption causes a shift of the cut-on to longer wavelength. As a result, the device I SC exhibits a continuous decrease (approximately a 2.5% drop with RG850 LP filter in a 5-min duration) even when the device temperature is controlled at 25 degrees C. To address the temperature gradient issue between colored glass LP filter and the reference cell, we propose the direct integration of thin-film LP semiconductor layer on reference cells. This type of LP-filter-integrated cell has shown minimal temperature-related I SC variation and can serve as a more reliable reference cell source for accurate performance measurements.

14 SOLAR ENERGY↗

DOE OSTI2020

NREL's Improved Linearity Testing of Photovoltaic Reference Cells

Photovoltaic devices are characterized under standard testing conditions that include a defined reference spectrum and total irradiance. International standards for reference cell calibrations require that reported reference cell response (typically Isc) vs. total irradiance must be linear. How can linearity be efficiently determined? In 2006 NREL developed a test bed, based on the "two-lamp method" that provided a low cost, but low accuracy method for determining whether cell response was linear with irradiance. This paper describes very simple changes to NREL's historical method [1] for determining linearity that yield greatly improved results. It also describes a method that can be used to quantify and correct for non-linearity.

41 EE - Solar Energy Technologies Office (EE-4S)↗

DOE OSTI2021

UV-Induced Degradation of High-Efficiency Solar Cells with Different Architectures

The ultraviolet-induced degradation (UVID) of solar panels is associated with the deterioration of cell performance and reduced reliability of packaging materials. Here we examine the UV stability of different architectures of high-efficiency solar cells without any encapsulation. Identical UV exposure tests were performed at two different labs using UVA-340 fluorescent lamps under different electrical bias configurations (open- or short-circuit) and irradiated cell surfaces (for bifacial technologies). Cell technologies, including heterojunction (HJ), interdigitated back-contact cells (IBC), passivated emitter rear contact (PERC), passivated emitter rear totally-diffused (PERT), are found to be more susceptible to UVID, leading to significant Isc loss (up to 4%) and P max loss (up to 15%) as compared to the conventional back surface field (Al-BSF) cells after exposure to UV irradiation of 8.92 MJ-m -2 -nm -1 at 340 nm. Additionally, the bifacial cells when irradiated from the backside exhibited greater photocurrent loss compared to the front side exposure, indicating potential sensitivity of rear surface passivation to UV radiation.

crystalline silicon↗

DOE OSTI2023

Development of a Novel Soiling Chamber for Testing Antisoiling Coatings: Preprint

This study presents the development and validation of a novel soiling chamber. The chamber is novel in that it includes wind induced soiling, feedback from a low-cost particulate monitor, and in-situ Isc measurements. Validation with side-by-side identical modules within the chamber produced soiling losses of 7% over 19 hours while the soiling ratio was always within 0.5% between the two modules. Initial side-by-side testing of an anti-soiling coated module versus and uncoated module demonstrated significant wind induced cleaning of the coated module. Specifically, the coated module showed only 0.8% soiling loss while the uncoated module reached as much as 10.5% soiling loss.

photovoltaic↗

DOE OSTI2022

Grafana Plugin: Chord Diagram (esnet-chord-diagram) v1

The Esnet chord diagram is a plugin to the open source Grafana platform which lets users create chord diagrams based on data queried from configured data sources. Its designed as a general purpose chord visualization, which we often use internally to show quantitative relationships between network customers. The software itself uses the d3.js library to generate visuals and its primary value is making it easy to use these within Grafana. Graphing library Here: https://github.com/d3/d3-chord ISC License Grafana https://github.com/grafana/grafana AGPL3.0

Balas, Edward↗

DOE OSTI2022

Network Models of Active Degradation Mechanisms and Pathways for Service Life Prediction of Indoor and Outdoor PV Modules

ct: PV service lifetime prediction (SLP) enables accurate calculation of levelized cost of energy (LCOE), which is crucial to rationalizing PV investment and installation. However, SLP is challeging since PV reliability in the field is affected by many combined factors, including various environmental stresses and module quality. In order to map out the active degradation mechanisms and pathways that best resemble real world conditions, we introduce the framework of a study protocol and use network models fitted to data, to enable analysis and SLP of complex PV systems with multiple active degradation mechanisms. The study protocol is the experimental design, including module variants and different exposure conditions, selection of evaluation methods, time-series data acquisition and training of network models to these data. We present SLP of minimodules in the lab and PV systems in the field. For lab SLP, minimodules with 8 variants based on manufacturer, architecture, and encapsulation were prepared and aged in modified damp heat with or without full spectrum light exposure. Stepwise I-V and Suns-Voc data acquisition tracks changes in electrical properties including Rs,IV, Isc,IV, Vmp,PIV providing insights into power loss of minimodules. Network structural equation modeling (netSEM) was utilized to construct degradation pathway models that identify active degradation mechanisms and predict power loss over time. For field SLP, datastreams of Pmp values and I-V curve datastreams of two types of modules installed in three distinctly different Köppen-Geiger climate zones for 9 years were acquired. With power loss modes corresponding to uniform current loss (ΔPIsc), recombination (ΔPVoc), series resistance (ΔPRs), and current mismatch (ΔPImis) determined, the performance loss rates (PLR) were determined using PVplr. We show how to establish a study protocol framework to ensure appropriate parametric variations and valid data collection from the variants of your complex systems. Then the data-driven netSEM model fitting provides a comprehensive mapping of multiple active degradation mechanisms, and accurate service life prediction.

network model, degradation, photovoltaic, solar↗

DOE OSTI2024

MCNPs Easy Sources for (α,n) (MESA):Verification with Sources4c

MESA is intended to be a direct re-implementation of the algorithms documented in the Sources manual in C++. However, some fundamental changes to the computational structure and logic were made to avoid the use of goto, require consistency in input definition, and reduce computational approximations in later steps of three-layer problems. In addition, MESA uses α-decay information from ISC libraries (based on ENDF). In most cases, differences between Sources4c and MESA are dominated by differences in decay energy spectra and intensities. To verify this we have reproduced 6 problems that are documented examples or samples in Sources4c. These problems cover the three types of problems MESA currently supports: homogeneous, interface, and three-layer.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2024

MCNPs Easy Sources for (α,n) (MESA) 1.0: A User’s Guide

MCNPs Easy Sources for Alpha,N (MESA) facilitates the construction of MCNP source definition cards for (α,n) sources. It is a complete re-write of the homogeneous, surface source, and three layer problem types from Sources4c. Please refer to this reference for documentation on the cross-sections and neutron emission spectra. The one departure from Sources4c is the use of alpha energies and activities from the ISC ENDF VII or VIII library specified by the user.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗

DOE OSTI2024

Talk Title: AI & Cybersecurity in ASEAN's Digital Future Venue: CyberForum: ASEAN Cyber Resilience Conference Hosted by: Indonesia Cyber Security Forum (ICSF) in coordination with US State Department's mission to ASEAN in Indonesia

The talk covers: * Quick orientation around AI * Quick review of relevant domains of Cybersecurity * The promise of AI in cybersecurity – applications * Discussion of the state of technology today, referencing Gartner Hype Cycle diagram * The peril of AI for cybersecurity – threats and risks * A roadmap for where to go from here, emphasizing a trained workforce, referencing published (ISC)^2 survey results

Benz, Zachary O.↗

DOE OSTI2026

Illinois Storage Corridor - CarbonSAFE Phase III: Policy, Regulatory, Legal and Permitting Characteristics; Subtask 5.5

The Illinois Storage Corridor (ISC) project aims to advance the commercial development and implementation of carbon capture and storage (CCS) technologies within a region in Illinois of suitable geology for carbon dioxide (CO 2 ) storage in deep saline aquifers. The project partners have annual emissions greater than 6.5 million tonnes per year; storage hubs are being explored at two sites—one near the One Earth Energy facility in east-central Illinois, and one near the Prairie State Generating Company campus in southwest Illinois. To implement the technology, legal, policy, and economic considerations must be explored. The United States Environmental Protection Agency (US EPA) administers the Underground Injection Control (UIC) program and is responsible for issuing Class VI permits to construct and operate CO 2 injection wells, i.e., a UIC Class VI well permit is required to inject CO 2 into the subsurface for geologic sequestration. The largest consideration of the Class VI well requirements is to protect underground sources of drinking water (USDWs). Additionally discussed are considerations for Class VI permits relating to public engagement. Besides permitting, property rights to storage sites, subsurface pore spaces, and areas for pipeline transportation must be secured. Pore space rights is still a novel concept being explored and not yet addressed by the Illinois legislature. It is believed that surface property rights are required for the subsurface pore space below, so long as there is not a separated mineral estate in the subsurface. Illinois legislature has addressed securing rights-of-way for CO 2 transportation, allowing for easements and the exercise of eminent domain to secure such rights. Economically, the incentives for CCS are ever-expanding. Recently, the federal government broadened the availability and increased the dollar-amounts for the § 45Q tax credits for geological storage of carbon oxides. Congress has also authorized the Advanced Industrial Facilities Development Program which allocates billions of dollars in funds to installing technology at industrial facilities to reduce greenhouse gas emissions. On the state level, Illinois has had its own incentives for CCS projects since 2009 and expanded its emission-related goals again in 2021. The law enacted in 2021 specifically creates a commission to explore implementing CCS at Prairie State Generating Company, a partner on the Illinois Storage Corridor project.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2024

Metalloproteomics Reveals Multi-Level Stress Response in Escherichia coli When Exposed to Arsenite

The arsRBC operon encodes a three-protein arsenic resistance system. ArsR regulates the transcription of the operon, while ArsB and ArsC are involved in exporting trivalent arsenic and reducing pentavalent arsenic, respectively. Previous research into Agrobacterium tumefaciens 5A has demonstrated that ArsR has regulatory control over a wide range of metal-related proteins and metabolic pathways. We hypothesized that ArsR has broad regulatory control in other Gram-negative bacteria and set out to test this. Here, we use differential proteomics to investigate changes caused by the presence of the arsR gene in human microbiome-relevant Escherichia coli during arsenite (AsIII) exposure. We show that ArsR has broad-ranging impacts such as the expression of TCA cycle enzymes during AsIII stress. Additionally, we found that the Isc [Fe-S] cluster and molybdenum cofactor assembly proteins are upregulated regardless of the presence of ArsR under these same conditions. An important finding from this differential proteomics analysis was the identification of response mechanisms that were strain-, ArsR-, and arsenic-specific, providing new clarity to this complex regulon. Given the widespread occurrence of the arsRBC operon, these findings should have broad applicability across microbial genera, including sensitive environments such as the human gastrointestinal tract.

Biochemistry & Molecular Biology↗

DOE OSTI2023

Results from an International Interlaboratory Study on Light- and Elevated Temperature-Induced Degradation (LETID) in Solar Modules

This presentation reports recently submitted results from an international interlaboratory comparison study on light- and elevated temperature-induced degradation (LETID) on crystalline silicon photovoltaic (PV) modules. A large global network of PV module manufacturers and PV testing laboratories collaborated to design a protocol for LETID detection, and screen a large and diverse set of prototype modules for LETID. We summarize the range of observed degradation and provide initial conclusions on the reproducibility of results across labs. In LETID-sensitive modules, both open-circuit voltage (VOC) and short-circuit current (ISC) degrade by a roughly similar magnitude. We observe, as do previous studies, that LETID affects each cell in a module differently. An investigation of the potential mismatch losses caused by nonuniform LETID degradation found that mismatch loss is insignificant compared to the direct LETID-related losses. We summarize the conclusions drawn from the study, provide an update on a forthcoming standard technical specification for LETID testing of PV modules (IEC TS 63342 ED1), and discuss unresolved questions and potential future work on LETID in PV modules.

degradation↗

DOE OSTI2026

Time Correlations from Steady-State Expectation Values

Recovering properties of correlation functions is typically challenging. On the one hand, experimentally, it requires measurements with a temporal resolution finer than the system’s dynamics. On the other hand, analytical or numerical analysis requires solving the system evolution. Here, we use recent results of quantum metrology with continuous measurements to derive general lower bounds on the relaxation and second-order correlation times that are both easy to calculate and measure. These bounds are based solely on steady-state expectation values and their derivatives with respect to a system parameter, and can be readily extended to the autocorrelation of arbitrary observables. We validate our method on two examples of critical quantum systems: a critical driven-dissipative resonator, where the bound matches analytical results for the dynamics, and the infinite-range Ising model, where only the steady state is solvable, and thus the bound provides information beyond the reach of existing analytical approaches. Our results can be applied to the experimental characterization of ultrafast systems and to the theoretical analysis of many-body models whose dynamics are hard to compute.

Górecki, Wojciech [INFN, Pavia] (ORCID:00000001991↗

DOE OSTI2025

Time correlations from steady-state expectation values

Recovering properties of correlation functions is typically challenging. On one hand, experimentally, it requires measurements with a temporal resolution finer than the system's dynamics. On the other hand, analytical or numerical analysis requires solving the system evolution. Here, we use recent results of quantum metrology with continuous measurements to derive general lower bounds on the relaxation and second-order correlation times that are both easy to calculate and measure. These bounds are based solely on steady-state expectation values and their derivatives with respect to a control parameter, and can be readily extended to the autocorrelation of arbitrary observables. We validate our method on two examples of critical quantum systems: a critical driven-dissipative resonator, where the bound matches analytical results for the dynamics, and the infinite-range Ising model, where only the steady state is solvable and thus the bound provides information beyond the reach of existing analytical approaches. Our results can be applied to experimentally characterize ultrafast systems, and to theoretically analyze many-body models with dynamics that are analytically or numerically hard.

Górecki, Wojciech [INFN, Pavia]↗

DOE OSTI2025

Time correlations from steady-state expectation values

Górecki, Wojciech [INFN, Pavia]↗

DOE OSTI2026

Progress and innovations in the TCV tokamak research programme

Research on the Tokamak à Configuration Variable addresses a wide range of key questions relevant to ITER and future fusion power plants. Over the past two years, highly productive experimental campaigns have led to major advances across several areas: the ITER baseline scenario; pedestal properties in low-collisionality, peeling-limited conditions; and the development of high- β N , non-inductive regimes. Alternative high-confinement scenarios have likewise received significant attention, with remarkable progress in quasi-continuous exhaust operation, X-point radiator plasmas, and negative triangularity configurations. Substantial achievements were also made in the mitigation or benign termination of runaway electron beams, in elucidating fast-ion loss mechanisms, and in improving exhaust behaviour in both conventional and alternative divertor geometries. These experimental results have been strongly supported by advances in modelling and their direct application to the experiment, ranging from gyrokinetic simulations of core and pedestal turbulence to fluid-based studies of scrape-off layer and divertor physics in diverse geometries. Plasma control has taken on an increasingly important role, with model-based and data-driven approaches now closely intertwined with physics studies. This article provides a overview of these recent activities, together with a brief outlook on forthcoming upgrades and next steps.

EPFL↗