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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Impacts of crystal orientation of GaAs on the interfacial structures and electrical properties of Hf{sub 0.6}La{sub 0.4}O{sub x} films

One of the major challenges in realizing the GaAs channel in the metal oxide semiconductor field effect transistor is the degrading in electron transport properties at the interface between GaAs and the gate oxide. In this study, Hf{sub 0.6}La{sub 0.4}O{sub x} gate oxide films were deposited at a low temperature (200 °C) on GaAs(111)A and GaAs(100) substrates by plasma enhanced atomic layer deposition. Microstructure analysis indicates that residuals of gallium oxide, arsenic oxide, and As element remained at the interface of Hf{sub 0.6}La{sub 0.4}O{sub x}/GaAs(100). On contrast, a smoother interface is observed between Hf{sub 0.6}La{sub 0.4}O{sub x} thin film and GaAs(111)A substrate. Furthermore, a reduction of interfacial layer is observed in Hf{sub 0.6}La{sub 0.4}O{sub x}/GaAs(111)A. Electrical characterization of the metal-insulator-semiconductor Pt/Hf{sub 0.6}La{sub 0.4}O{sub x}/n-GaAs(111)A capacitor indicated a reduction of D{sub it} and leakage current compared with the capacitor fabricated on GaAs(100)

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Heat-Treated TiO{sub 2} Plasma Spray Deposition for Bioactivity Improvement in Ti-6Al-4V Alloy

In the present study, titanium di-oxide (TiO{sub 2}) coating has been developed on Ti-6Al-4V substrate by plasma spray deposition. Followed by plasma spraying, heat treatment of the sprayed sample has been carried out by isothermally holding it at 823 K (550 °C) for 2 h. Microstructural analysis shows the presence of porosity and unmelted particles on the as-sprayed surface, the area fraction of which reduces after heat treatment. X-ray diffraction analysis shows the phase transformation from anatase (in precursor powder) to rutile (in as-sprayed coating and the same after heat treatment). There is an improvement in nano-hardness, “Young’s modulus” and wear resistance in plasma-sprayed TiO{sub 2} coating (as-sprayed as well as post-heat-treated condition) as compared to as-received Ti-6Al-4V, though post-heat treatment offers a superior hardness, “young’s modulus” and wear resistance as compared to as-sprayed coating. The corrosion behavior in “hank’s solution” shows decrease in corrosion resistance after plasma spraying and post-heat treatment as compared to as-received substrate. A significant decrease in contact angle and improvement in bioactivity (in terms of apatite deposition) were observed in TiO{sub 2}-coated surface as compared to as-received Ti-6Al-4V.

36 MATERIALS SCIENCE↗
DOE OSTI2018

The Effect of Boron and Zirconium on the Structure and Tensile Properties of the Cast Nickel-Based Superalloy ATI 718Plus

The effects of boron and zirconium on cast structure, hardness, and tensile properties of the nickel-based superalloy 718Plus were investigated. For this purpose, five alloys with different contents of boron and zirconium were cast via vacuum induction melting and then purified via vacuum arc remelting. Microstructural analysis by light-optical microscope and scanning electron microscope equipped with energy-dispersive x-ray spectroscopy and phase studies by x-ray diffraction analysis were performed. The results showed that boron and zirconium tend to significantly reduce dendritic arm spacing and increase the amount of Laves, Laves/gamma eutectic, and carbide phases. It was also found that boron led to the formation of B{sub 4}C and (Cr, Fe, Mo, Ni, Ti){sub 3}B{sub 2} phases and zirconium led to the formation of intermetallic phases and ZrC carbide. In the presence of boron and zirconium, the hardness and its difference between dendritic branches and inter-dendritic spaces increased by concentrating such phases as Laves in the inter-dendritic spaces. These elements had a negative effect on tensile properties of the alloy, including ductility and strength, mainly because of the increase in the Laves phase. It should be noted that the largest degradation of the tensile properties occurred in the alloys containing the maximum amount of zirconium.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Spatial and temporal characterization of municipal solid waste based on resource recovery pathways

This study presents a two-year, quarterly assessment of MSW across four source sectors (residential, schools, restaurants, and grocery stores) from sixteen sites across five U.S. states. MSW was manually sorted into 27 categories and aggregated into pathway fractions: high-moisture (HM) organics, low-moisture (LM) organics, recyclable (RC) materials, and residuals for disposal. Organics represented 89 % of the MSW stream. The largest fraction was HM organics consisting of food waste (31 %) and yard waste (3 %), with large coefficient of variations (CV), 79 and 278 %, respectively, reflecting high seasonal and site variability that varied significantly (p < 0.01) across sampling periods. The HM fraction showed properties favorable for anaerobic digestion, with moisture content ranging from 56 to 95 % and volatile solids ranges of 86-95 %. In contrast, the LM and RC fractions remained more stable (plastics CV = 41 %; paper CV = 53 %) with heating values up to 26.9 MJ/kg across sources, reflecting suitability for gasification. Microstructural analysis revealed less porosity in residential waste sampled at the landfill, which can influence preprocessing efficiency and microbial accessibility. Pathway informed allocations showed that 35 % of MSW is suitable for anaerobic digestion, 36 % for gasification, and 18 % for recycling, leaving 11 % requiring landfill disposal. These results provide quantitative evidence to determine feedstock allocation, waste-to-energy system design, and the development of data-driven sustainability and resource recovery strategies within a circular bioeconomy.

09 BIOMASS FUELS↗
DOE OSTI2018

Microstructure characterisation of un-melted particles in a plasma sprayed CoNiCrAlY coating

Highlights: • The microstructure of the CoNiCrAlY powder particles was studied. • The un-melted particles in the VPS CoNiCrAlY coating were investigated. • A semi-continuous β-phase layer was found around the un-melted particles. • Micro-cracks were formed along the un-melted particles under compression. - Abstract: Un-melted particles in thermally sprayed coatings are usually classified as impurity elements. Such impurities have a strong influence on the coating behaviour due to their different microstructural characteristics. In this work, the microstructural and mechanical characteristics of un-melted particles in a vacuum plasma sprayed CoNiCrAlY coating have been investigated. Microstructural analysis revealed the dendritic structure of the as-received powder and a spherical core inside the powder particle. The as-deposited coating comprised a dual phase structure of γ-Ni and β-NiAl, with coarse grains ranging 1–2 μm and fine grains ranging 500 nm or even less. Un-melted particles were found to exist in the coating after plasma spraying. The grain structure in the un-melted particles has not been fully developed, as characterised via electron backscattered diffraction (EBSD). It is shown that the spherical core in the initial powder was retained as un-melted particles due to insufficient melting during plasma spraying. In addition, a semi-continuous β-phase layer was found at the un-melted particle boundaries. Due to the inherently brittle nature of the β-phase layer and poor bonding at the particle boundaries, cracking along the un-melted particle boundaries occurred under compression.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Length-scale-dependent nanoindentation creep behaviour of Ti/Al multilayers by magnetron sputtering

This study presented length-scale-dependent room temperature creep behaviour of Ti/Al multilayers by nanoindentation. Ti/Al multilayers with individual layer thickness ranging from 10 nm to 250 nm were prepared by a direct current magnetron sputtering method. Microstructural analysis showed that the prepared Ti/Al multilayers were polycrystalline, with strong Ti (0002) and Al (111) texture. Nanoindentation creep tests were performed to examine the time-dependent creep deformation, stress exponent, creep strain rate sensitivity and contact creep compliance of the multilayers at room temperature. It was found that both the maximum creep deformation and the creep strain rate sensitivity increase with an increase in the individual layer thickness, indicating a length-scale-dependent creep behaviour of the Ti/Al multilayers. The values of stress exponent were found to lay in the range of 15.74–61.46, implying that the creep behaviour of the multilayers was controlled by the dislocation creep mechanism. Finally, the contact creep compliances of the Ti/Al multilayers were well modelled by a two-element Kelvin-Voigt model. From this, it was determined that the creep numbers and retardation times increased with increased individual layer thickness.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2014

Three-dimensional EBSD characterization of thermo-mechanical fatigue crack morphology in compacted graphite iron

In cylinder heads made of compacted graphitic iron (CGI), heating and cooling cycles can lead to localized cracking due to thermo-mechanical fatigue (TMF). To meticulously characterize the complex crack path morphology of CGI under TMF condition, in relation to microstructural features and to find out how and by which mechanisms the cracks predominantly develop, three-dimensional electron back scattering diffraction (EBSD) was employed. Based on the precise quantitative microstructural analysis, it is found that graphite particles not only play a crucial role in the crack initiation, but also are of primary significance for crack propagation, i.e. crack growth is enhanced by the presence of graphite particles. Furthermore, the density of graphite particles on the fracture plane is more than double as high as in any other arbitrary plane of the structure. The obtained results did not indicate a particular crystallographic preference of fracture plane, i.e. the crystal plane parallel to the fracture plane was nearly of random orientation. - Highlights: • Crystallographic features of a thermo-mechanical fatigue (TMF) crack were studied. • Wide-field 3D EBSD is used to characterize the TMF crack morphology. • Data processing was applied on a large length scale of the order of millimeters. • Graphite density in the fracture plane is much higher than any other random plane. • It is revealed that crack growth is enhanced by the presence of graphite particles.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Investigation of nanostructured Al-10 wt.% Zr material prepared by ball milling for high temperature applications

Ground chips of as-cast Al-10 wt.% Zr alloy were subjected to mechanical alloying (MA) with 5 vol.% of nanodiamond addition in a high energy planetary ball-mill. The aim of this work was to investigate the microstructure, phase transformation and mechanical properties of the material both after MA and after subsequent annealing. Optical and transmission electron microscopes were used for morphological and microstructural analysis. The effect of milling time on powder microhardness, Al lattice parameter, lattice microstrain and crystallite size was determined. It was shown that mechanical alloying of as-cast Al-10wt.%Zr alloy during 20 h leads to a complete dissolution of the primary tetragonal Al{sub 3}Zr crystals in aluminum. At the same time, the powder microhardness increases to 370 HV. Metastable cubic Al{sub 3}Zr phase nanoparticles precipitate from the Al solution due to its decomposition after annealing, however, the Al solid solution remains supersaturated and nanocrystalline. Compression tests at room temperature and at 300 °C showed that the strength values of the hot-pressed samples reach 822 MPa and 344 MPa, respectively. - Highlights: •As-cast Al-10 wt.% Zr alloy was mechanically alloyed with 5 vol.% nanodiamond. •The primary tetragonal Al{sub 3}Zr crystals were completely dissolved in Al after 20 h. •Cubic Al{sub 3}Zr phase nanoparticles precipitated from Al solution after aging. •The aged bulk material showed a high strength at room and elevated temperatures.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Single and multi-layered core-shell structures based on ZnO nanorods obtained by aerosol assisted chemical vapor deposition

Core–shell nanorod structures were prepared by a sequential synthesis using an aerosol assisted chemical vapor deposition technique. Several samples consisting of ZnO nanorods were initially grown over TiO{sub 2} film-coated borosilicate glass substrates, following the synthesis conditions reported elsewhere. Later on, a uniform layer consisting of individual Al, Ni, Ti or Fe oxides was grown onto ZnO nanorod samples forming the so-called single MO{sub x}/ZnO nanorod core–shell structures, where MO{sub x} was the metal oxide shell. Additionally, a three-layer core–shell sample was developed by growing Fe, Ti and Fe oxides alternately, onto the ZnO nanorods. The microstructure of the core–shell materials was characterized by grazing incidence X-ray diffraction, scanning and transmission electron microscopy. Energy dispersive X-ray spectroscopy was employed to corroborate the formation of different metal oxides. X-ray diffraction outcomes for single core–shell structures showed solely the presence of ZnO as wurtzite and TiO{sub 2} as anatase. For the multi-layered shell sample, the existence of Fe{sub 2}O{sub 3} as hematite was also detected. Morphological observations suggested the existence of an outer material grown onto the nanorods and further microstructural analysis by HR-STEM confirmed the development of core–shell structures in all cases. These studies also showed that the individual Al, Fe, Ni and Ti oxide layers are amorphous; an observation that matched with X-ray diffraction analysis where no apparent extra oxides were detected. For the multi-layered sample, the development of a shell consisting of three different oxide layers onto the nanorods was found. Overall results showed that no alteration in the primary ZnO core was produced during the growth of the shells, indicating that the deposition technique used herein was and it is suitable for the synthesis of homogeneous and complex nanomaterials high in quality and purity. In addition, materials absorptance determined from the total transmittance and reflectance spectra revealed a broader absorption interval including visible light, indicating potential uses of these nanostructures on solar energy appliances. - Graphical abstract: Display Omitted - Highlights: • Uniform ZnO nanorods (core)–metal oxide (shell) were obtained sequentially by AACVD. • Shells were structured of homogeneous single or multi-layered non-mixed metal oxides. • ZnO nanorod core was preserved during the shell synthesis. • Optical absorptance revealed visible interval absorption for FeO{sub x} shell samples. • Materials can be suitable for photocatalytic or photovoltaic applications.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2021

Laser-Interference Surface Preparation for Enhanced Coating Adhesion and Adhesive Joining of Multi-Materials (Final Project Report)

This report investigates a laser-interference surface treatment as a non-contact, i.e., without major solid/liquid medium application or abrasion, and non-chemical surface preparation method for aerospace coating systems. It was proposed to use the laser-interference technique to structure surfaces of Al and/or Ti, creating "rough" surfaces with pre-engineered series of ridges and valleys at submicron scale. The science goal of this study was to develop an understanding of the surface microstructure, topology, and physical mechanisms that would improve adhesion and corrosion protection of Al2024-T3. Microstructure analysis indicates that the laser-interference structuring (LIS) was found to reduce the formation of CuMn-rich precipitates in Al 2024-T3 over a 500-800 nm depth from top surface. The X-cut and cross-hatch coating adhesion ratings indicate that the LIS specimens meet the performance requirements in the coating adhesion specifications by having a higher or identical ranking to those specimens prepared with current state-of-the-art chemical conversion or sulfuric acid anodizing. After the ASTM B117 corrosion exposure, it was found that the laser processed specimens exhibited only few blisters. It was found that the corrosion damage was minimized at a laser rastering speed of 4 mm/s, for which only 33% of specimens developed very minor corrosion damage. The ASTM D1654 creepage ratings, used to evaluate corrosion damage along the scribe lines, were found to be at least nine for all coated panels. These results indicate that the laser-interference technique with the additional acetone wiping has the potential to be further developed as a minor chemical surface preparation technique for chromate-containing epoxy primers coatings.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Influence of Particle Size on the Basic and Time-Dependent Rheological Behaviors of Cemented Paste Backfill

The rheological properties of cemented paste backfill (CPB) significantly influence the material’s transportability, and these properties are strongly affected by the material’s particle size. This paper mainly focuses on the influence of particles size on the basic and time-dependent rheological behaviors of CPB. The rheology tests and microstructure analysis were conducted using multiple CPB samples with different solid contents, cement contents, and particle sizes. Results show that the CPB samples with finer particle sizes have a lower apparent maximum packing density compared to the CPB samples with larger particle sizes. Fresh CPB mixture samples exhibit shear thinning characteristics which are more pronounced in samples with larger particle sizes and higher volume fraction to apparent maximum packing density (ϕ/ϕ{sub m}) ratios. When the ϕ/ϕ{sub m} ratio is lower than 0.875, the samples with finer particle sizes display a higher yield stress but less time-dependent rheological behavior than coarser samples. In all CPB samples that contained cement, the shear stress decreases first and then increases over the shearing time when samples are sheared at a constant shear rate. In the CPB samples without cement, samples with finer particle sizes show lower apparent viscosities, and it is observed in the sample with the finest particles that the shear stress only decreases over the shearing time. Moreover, it is found that the number of hydration products and the rate of particle sedimentation are both higher in samples with larger particle sizes, which result in these samples having higher apparent viscosities.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Dependence of the Electron Beam Energy and Types of Surface to Determine EBSD Indexing Reliability in Yttria-Stabilized Zirconia

Electron backscatter diffraction (EBSD) is a powerful technique for the surface microstructure analysis. EBSD analysis of cubic yttria-stabilized zirconia (YSZ) in two and three dimensions (2-D, 3-D) is demonstrated using sequential slicing from a focused ion beam (FIB) followed by EBSD mapping to represent 3-D reconstructed high density grain structure with random orientation. The statistics related to accuracy of EBSD band detection shows that probability of accurate grain orientation detection increased significantly when the electron beam energy is increased from 10 kV to 30 kV. As a result of better sampling with increased interaction volume, a disparity between local and average grain orientation angle also exhibited the dependence of the electron beam energy to determine the accuracy of grain orientation. To study the accuracy and quality of EBSD band detection as a function of surface roughness and over layer formation, rapid EBSD measurement tests are performed on (a) YSZ surfaces ion-polished at ion beam energies of 65 nA at 30 kV and 1 nA at 30 kV and (b) carbon coated versus uncoated YSZ surfaces. The EBSD results at both 10 kV and 30 kV electron beam energies indicate that EBSD band detection accuracy is negatively affected by surface roughness and amorphous over layer formation.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Effect of Mn addition on deformation behaviour of 23% Cr low nickel duplex stainless steel

Highlights: • Increasing Mn content obviously affects dynamic softening behaviour of flow curves. • More complete austenite DRX occurred with middle Mn addition of 10.3% at 1 s{sup −1}. • The constitutive equations for different Mn addition alloys are developed. • The values of activation energy and Z parameter are lowest with middle Mn addition. • Different Mn addition processing maps with increasing strain were established. - Abstract: Isothermal compression testing of 23% Cr low nickel duplex stainless steels, with different Mn concentrations, was investigated in the temperature range of 1173–1423 K, the strain rate range of 0.01–10 s{sup −1} and with a height reduction of 70%. Increasing the Mn content from 6.3 to 14.1% affected the deformation dynamic softening behaviour of flow curves at lower temperature and higher strain rate. It was also observed that increasing the deformation stain rate contributed to flow softening, and was caused by dynamic recrystallization (DRX) as a function of Mn addition. Deformation microstructure analysis demonstrated that more complete austenite phase DRX occurred with 10.3% Mn addition than that with 6.3% Mn addition at 1 s{sup −1}, but an excessive Mn content of 14.1% was unfavourable due to the increase of austenite fraction and stacking fault energy enhancement. Increasing the strain rate to 10 s{sup −1} promoted austenite phase DRX at 1323 K with the Mn addition under large strain. Meanwhile, the ferrite phase DRX occurred at 1173 K/1–10 s{sup −1} with 6.3% Mn, and was weakened with higher Mn addition. Compared to the 6.3% and 14.1% Mn, continuous DRX occurred at 1323 K/1 s{sup −1} with 10.3% Mn, due to the larger fraction of high angle misorientations. The values for the activation energy and Zener–Hollomon parameter decreased with Mn addition from 6.3 to 10.3%, and then increased with a higher Mn addition of 14.1%, indicating that a proper content of Mn addition can reduce the thermal deformation resistance and promote DRX. The constitutive equations for different Mn addition alloys were developed using a hyperbolic sine equation. Processing maps with different Mn addition for the strains of 0.3, 0.6 and 1.2 were established. The 10.3% Mn content sample corresponded to the lowest instability region, implying that the workability was improved with the middle Mn addition.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Study of structural and ferromagnetic resonance properties of spinel lithium ferrite (LiFe{sub 5}O{sub 8}) single crystals

The effect of B-site cation ordering on the room temperature structural and ferromagnetic resonance (FMR) properties of single crystal spinel lithium ferrite (LiFe{sub 5}O{sub 8}, LFO) have been investigated. A detailed microstructural analysis is done through X-ray diffraction, polarized Raman spectroscopy, and transmission electron microscopy (TEM) to examine the effect of post-annealing on the B-site cation ordering. The X-ray diffraction pattern of the as-grown crystal indicates a disordered state of the crystal. However, the annealed sample shows additional superlattice reflections corresponding to the ordered phase. This ordering is further confirmed by Raman spectra and TEM images, which reveal ordering of Li and Fe ions at the octahedral sites contrasting with the relatively high degree of octahedral site disorder in the as-grown crystal. To study the effect of B-site ordering on the magnetic properties and FMR linewidth, vibrating sample magnetometry and broadband FMR measurements have been performed for both the ordered and disordered phases of lithium ferrite. The value of saturation magnetization for both phases is ∼290 emu/cm{sup 3}. A single mode FMR profile is observed for both phases with little distortion. The linewidth characteristics of the ordered and disordered phases of lithium ferrite phases are compared, and it is observed that the linewidth is independent of the cation ordering. Both the phases exhibit a low linewidth (∼26 Oe at 30 GHz) and the effective damping parameter for the as-grown and annealed samples is determined to be 0.0021 ± 0.0001.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Unveiling Nickel Chemistry in Stabilizing High-Voltage Cobalt-Rich Cathodes for Lithium-Ion Batteries

We present a practical solution to increase the stability of 4.45 V LiCoO 2 via high-temperature Ni doping, without adding any extra synthesis step or cost. We identify how a putative uniform bulk doping with highly soluble elements can profoundly modify the surface chemistry and structural stability from systematic chemistry and microstructure analysis. This modification has an electronic origin, where surface-oxygen-loss induced Co reduction that favors tetrahedral site and causes damaging spinel phase formation is replaced by Ni reduction that favors octahedral site and creates a better cation-mixed structure. Furthermore, our findings point to many unknown surface effects on the electrochemical performance of battery electrode materials hidden behind extensively practiced bulk doping strategy. The new understanding of complex surface chemistry is expected to help develop higher-energy-density cathode materials for battery applications.

25 ENERGY STORAGE↗
DOE OSTI2021

Structural Design Variations in Beetle Elytra

Abstract Beetles typically use their protective wing coverings or elytra to shield their membranous hindwings from the environment. Elytra in some terrestrial species have evolved a greater protective role capable of shielding the organism from powerful antagonistic predators. The structure–function relationships of these biological composites identify how architectural and chemical variations of the cuticle are tuned to create light‐weight, impact resistant composites. Specifically, the elytral structures of a tree dwelling beetle capable of flight, Trypoxylus dichotomus , and a terrestrial beetle incapable of flight, Phloeodes diabolicus , are compared to understand how their varied environmental needs forged the elytra to facilitate fight or resist fatal predator strikes. Mechanical and microstructural analysis reveals P . diabolicus has a harder, stiffer elytra that incorporate through‐thickness fibers to resist greater mechanical stresses imposed by bending and puncture. Conversely, the elytra of T . dichotomus have a compliant structure with large voids that facilitates localized deformation. Variations in flexural strength and puncture resistance remain attributed to P . diabolicus possessing a thicker cuticle with a greater degree of cross‐linking and an increased amount of endocuticular layers. These findings may provide useful insight into the design and manufacturing of composite materials for use in light‐weight or energy‐absorbing applications.

Rivera, Jesus↗
DOE OSTI2023

Boosting Piezoelectricity by 3D Printing PVDF‐MoS 2 Composite as a Conformal and High‐Sensitivity Piezoelectric Sensor

Abstract Additively manufactured flexible and high‐performance piezoelectric devices are highly desirable for sensing and energy harvesting of 3D conformal structures. Herein, the study reports a significantly enhanced piezoelectricity in polyvinylidene fluoride (PVDF) achieved through the in situ dipole alignment of PVDF within PVDF‐2D molybdenum disulfide (2D MoS 2 ) composite by 3D printing. The shear stress‐induced dipole poling of PVDF and 2D MoS 2 alignment are harnessed during 3D printing to boost piezoelectricity without requiring a post‐poling process. The results show a remarkable, more than the eight‐fold increment in the piezoelectric coefficient ( d 33 ) for 3D printed PVDF‐8wt.% MoS 2 composite over cast neat PVDF. The underlying mechanism of piezoelectric property enhancement is attributed to the increased volume fraction of β phase in PVDF, filler fraction, heterogeneous strain distribution around PVDF‐MoS 2 interfaces, and strain transfer to the nanofillers as confirmed by microstructural analysis and finite element simulation. These results provide a promising route to design and fabricate high‐performance 3D piezoelectric devices via 3D printing for next‐generation sensors and mechanical–electronic conformal devices.

2D MoS2↗
DOE OSTI2023

Anthradithiophene (ADT)-Based Polymerized Non-Fullerene Acceptors for All-Polymer Solar Cells

Realizing efficient all-polymer solar cell (APSC) acceptors typically involves increased building block synthetic complexity, hence potentially unscalable syntheses and/or prohibitive costs. Here we report the synthesis, characterization, and implementation in APSCs of three new polymer acceptors P1–P3 using a scalable donor fragment, bis(2-octyldodecyl)anthra[1,2-b : 5,6-b’]dithiophene-4,10-dicarboxylate (ADT) co-polymerized with the high-efficiency acceptor units, NDI, Y6, and IDIC. Further, all three copolymers have comparable photophysics to known polymers; however, APSCs fabricated by blending P1, P2 and P3 with donor polymers PM5 and PM6 exhibit modest power conversion efficiencies (PCEs), with the champion P2-based APSC achieving PCE=5.64 %. Detailed morphological and microstructural analysis by AFM and GIWAXS reveal a non-optimal APSC active layer morphology, which suppresses charge transport. Despite the modest efficiencies, these APSCs demonstrate the feasibility of using ADT as a scalable and inexpensive electron rich/donor building block for APSCs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗