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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Broadband light emitting zero-dimensional antimony and bismuth-based hybrid halides with diverse structures

Low-dimensional organic–inorganic metal halides have recently attracted extensive attention because of their various structures and distinguished photoelectric properties. Herein, we report a series of new zero-dimensional organic–inorganic hybrid metal halides: (TMEDA) 3 Bi 2 Cl 12 ·H 2 O, (TMEDA) 3 Bi 2 Br 12 ·H 2 O, (TMEDA) 3 Sb 2 Br 12 ·H 2 O, and (TMEDA) 5 Sb 6 Cl 28 ·2H 2 O [TMEDA = N,N,N'·trimethylethylenediamine]. (TMEDA) 3 M 2 X 12 ·H 2 O (M = Bi or Sb, X = Cl or Br) crystallizes in the monoclinic space group P2 1 /n, and (TMEDA) 5 Sb 6 Cl 28 ·2H 2 O crystallizes in the orthorhombic space group Pnma. (TMEDA) 3 M 2 X 12 possesses a zero-dimensional structure with the metal halide ions of [MBr 6 ] 3- isolated by the organic TMEDA 2+ cations. Interestingly, the (TMEDA) 5 Sb 6 Cl 28 ·2H 2 O structure consists of a combination of corner-connected octahedra [Sb 4 Cl 18 ] 6- and edge-shared [Sb 2 Cl 10 ] 4- , which is quite rare. The light emission of all these compounds was measured, and (TMEDA) 3 Sb 2 Br 12 ·H 2 O exhibits the most intense luminescence. Upon 400 nm ultraviolet light excitation, (TMEDA) 3 Sb 2 Br 12 ·H 2 O exhibited strong broadband yellow emission centered at 625 nm with a full-width at half-maximum of ~150 nm originating from self-trapped excitons. In conclusion, this work suggests the possibility of new types of hybrid halides by introducing different metal centers and probing the structural evolution and photoluminescent properties, serving as a reference for the relationship between structure and luminescent performance and demonstrating their potential use as phosphors in light-emitting diodes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Antimony doping to enhance luminescence of tin ($\mathrm{IV}$)-based hybrid metal halides

Lead-based organic–inorganic metal halides (OIMHs) have recently attracted special attention due to their efficient broadband photoluminescence. However, the toxicity of lead poses a challenge for their further development. In this paper we selected Sn(IV) as the metal center to synthesize the environmentally friendly and stable luminescent OIMHs (C 9 H 15 N 3 ) 2 SnCI 8 and C 9 H 15 N 3 ) 2 SnBr 8 (C 9 H 13 N 3 is 1-(2-2-pyridyl)piperazine). Both compounds possess zero-dimensional structures, crystallizing in the monoclinic space group P2 1 /c, and their optical band gaps were experimentally determined to be 3.19 and 2.60 eV, respectively. Under UV excitation at room temperature, (C 9 H 15 N 3 ) 2 SnCI 8 exhibited double-peak emissions centered at 405 and 688 nm, which were attributed to the organic cation and inorganic octahedra, respectively. Upon introducing 5s 2 -lone-pair-containing Sb 3+ in (C 9 H 15 N 3 ) 2 SnCI 8 , self-trapped emission was promoted, and the photoluminescence quantum yield increased from ~1% to ~17.84%. This work suggests effective strategies for finding environmentally friendly stable OIMHs and for further enhancing the luminescence properties through lone-pair-containing cation doping.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Buckled honeycomb antimony: Higher order topological insulator and its relation to the Kekulé lattice

Higher order topological tnsulators are d-spatial dimensional systems featuring topologically protected gapless states at their (d-n)-dimensional boundaries. With the help of ab initio calculations and tight-binding models along with symmetry considerations, we show that monolayer buckled honeycomb structures of group-V elements (Sb, As), which have already been synthesized, belong in this category and have a spinless charge fractionalization of $\frac{e}{2}$ at the corner states as well as weak topological edge states, protected by the S 6 symmetry operation, which classify this system as a quadrupole topological insulator. The robustness of these edge and corner states to perturbations is explicitly demonstrated.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Copper Antimony Chalcogenide Thin Film PV Device Development

Emerging ternary chalcogenide thin film solar cell technologies, such as CuSbS2 and CuSbSe2, have recently attracted attention as simpler alternatives to quaternary Cu2ZnSnS4 (CZTS). Despite suitable photovoltaic properties, the initial energy conversion efficiency of CuSbS2 is rather low (0.3%). Here, we report on our progress towards improving the efficiency of CuSbS2 solar cells using a high throughput approach. The combinatorial methodology quickly results in baseline solar cell prototypes with 0.6% efficiency, and then modification of the back contact architecture leads to 1% PV devices. We then translate the optimal CuSbS2 synthesis parameters to CuSbSe2 devices, which show 3% efficiencies.

14 SOLAR ENERGY↗
DOE OSTI2022

Hybrid Functional Calculations for Antimony Doping in CdTe

CdTe-based solar cells are leading thin-film photovoltaic technology, with efficiencies over 22%, but still much lower than the theoretical maximum of 29%. Further improvements will rely on increasing the open-circuit voltage Voc, which, in turn, depends on carrier density and lifetime. Using hybrid density functional calculations, we investigate Sb doping of CdTe, focusing on its limitation as shallow acceptor and the formation of compensating AX center. Paying special attention to supercell size and effects of spin-orbit coupling, we predict an ionization energy of 116 meV in the dilute limit, much closer to recent experimental value of 103 meV from temperature-dependent Hall measurements in bulk single crystals, and in contrast to much larger values from previous calculations. We also find that the Sb-related AX centers are not major compensation centers in Sb-doped CdTe.

14 SOLAR ENERGY↗
DOE OSTI2024

Antimony Chloride Treatments of CdTe-Based Solar Cells

Development of a new SbCl3-based solution treatment for chloride activation of CdTe-based solar cells is described. Activation was confirmed with CdSeTe:Sb devices exhibiting VOC > 550 mV and JSC > 25 mAcm-2. Treatment optimization showed strong effects of annealing time and temperature on cell properties. Material characterization indicated surface conversion of CdSeTe to CdCl2 and Sb2Te3 with SbCl3 treatment. However, no reaction products were formed with treatment under inert conditions, which was coupled with poor device performance. Drying the SbCl3 films at controlled humidity conditions confirmed that exposure to high relative humidity is critical for CdSeTe activation, through hydrolysis of SbCl3. Mechanistic details of SbCl3 speciation during hydrolysis and annealing to activate CdSeTe are discussed.

14 SOLAR ENERGY↗
DOE OSTI2025

The effects of antimony incorporation on the optoelectronic properties of Cd(Se,Te) photovoltaics

One historical limitation of CdTe PV devices has been the open circuit voltage (VOC) deficit (difference between theoretical maximum VOC and measured values). While non-radiative recombination at extended structural defects and interfaces negatively impacts VOC, intentionally adding impurities (dopants) to increase the concentration of free carriers in the photovoltaic (PV) absorber material can increase the VOC. In this contribution we present a detailed analysis of the Sb doped CdTe and the Cd(Se,Te) alloy system via electron beam induced current (EBIC) measurements and the presence as well as spatial distribution of defect levels through cathodoluminescence spectrum imaging (CLSI).

14 SOLAR ENERGY↗
DOE OSTI2017

Antimony segregation in Si layers grown by molecular beam epitaxy on Si wafers with different crystallographic orientations

The segregation of Sb in Si layers grown by molecular beam epitaxy on Si substrates with the (111), (110), and (115) crystallographic orientations is studied; the results obtained for these orientations are compared with those obtained for the most widely used orientation (001). It is found that there is a qualitative similarity between the temperature dependences of the Sb segregation ratio (r) for all studied orientations; in particular, it is possible to separate two characteristic temperature ranges corresponding to the kinetically limited and equilibrium regimes of segregation. However, quantitatively, the values of r for the orientations under study differ significantly from those for the Si(001) case at the same temperatures. For all orientations, narrow temperature ranges within which the values of r vary by nearly five orders of magnitude are revealed for all dependences of r on the growth temperature. This finding allows us to adopt the method of selective doping, which was for the first time suggested by us for structures grown on Si (001) and is based on the controlled use of the segregation effect, to structures grown on Si substrates with an orientation different from (001). Using this method, selectively doped Si:Sb/Si(111) structures are fabricated; in these structures, a variation in the Sb concentration by an order of magnitude occurs at the scale of several nanometers.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Extending Magnetic Core Shell Nanoparticle Extraction Technology to Cesium and Antimony Removal from Geothermal Brines in New Zealand - CRADA 440

Geo40 Limited has developed and deployed a process to remove silica from geothermal fluids and produce a high-margin specialty colloidal silica product comparable to market leaders. Geo40 now wishes to explore opportunities to extend their mineral extraction operations to other elements that are present in these brines. Geo40 has identified Cs present in Ohaaki brines at ppm level amounts that could be sold to known customers if it could be produced at an attractive price. With support from DOE’s Geothermal Technologies Office, a simple and highly cost-effective magnetic nanofluid method for extraction of rare earth elements (REEs) from geothermal brine solutions has been developed and demonstrated at the laboratory bench scale at Pacific Northwest National Laboratory (PNNL). Moselle Technologies has acquired a license to the background IP associated with this technology and wishes to foster commercial deployment by supporting applications of the technology beyond REEs, including Cs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Extending Magnetic Core Shell Nanoparticle Extraction Technology to Cesium and Antimony Removal from Geothermal Brines in New Zealand

Our industrial client (Geo40) has developed and deployed a process to remove silica from geothermal fluids and produce a high-margin specialty colloidal silica product comparable to those of market leaders. Geo40 now wishes to explore opportunities to extend their mineral extraction operations to other elements that are present in these brines. Geo40 has identified cesium (Cs) that is present in Ohaaki brines (pH ~8–8.5) at parts per million levels and could be sold to customers if it could be produced at an attractive price. With support from the Department of Energy’s (DOE’s) Geothermal Technologies Office, a simple and highly cost-effective magnetic nanofluid method for extraction of rare earth elements (REEs) from geothermal brine solutions has been developed and demonstrated at the laboratory bench scale at Pacific Northwest National Laboratory (PNNL). Core shell sorbent particles are produced using an iron oxide core particle, which is used to anchor and grow a surrounding adsorbent shell functionalized with a chelating ligand that selectively binds REEs. We extended PNNL’s work by exploring new sorbent shells that are highly selective for Cs. Uptake of Cs was measured as a function of exposure time by analyzing solution samples extracted from batch sorption tests.

15 GEOTHERMAL ENERGY↗