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At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Solution-based spin-coated tin sulfide thin films for photovoltaic and supercapacitor applications

Highlights: • Tin sulfide (SnS{sub x}) thin films were prepared by solution-based spin coating. • The SnS{sub x} films annealed at 500 °C exhibited a pure SnS phase. • The films exhibited direct band gap of 1.4 eV which is near to solar maximum. • The films with the pure SnS phase exhibited a specific capacitance of 42 F g{sup ―1}. - Abstract: In this study, tin sulfide (SnS{sub x}) thin films were prepared using a solution-based spin-coating method. The annealing temperature was observed to play a dominant role in determining the phase, crystallinity, and morphology of the SnS{sub x} thin films. The results obtained from X-ray diffraction, as well as optical and electrical measurements, revealed that the films annealed at 500 °C exhibit a pure SnS phase, with a carrier concentration and direct band gap of ∼10{sup 12} and 1.4 eV, respectively. To explore the applications of SnS in supercapacitors, electrochemical measurements were performed in a 0.2 M NaOH solution. The results indicated that films with a pure SnS phase have a high specific capacitance of 42 F g{sup ―1} at a current density of 2 A g{sup ―1}. The synthesized SnS thin films demonstrate potential for applications in electrochemical capacitors and solar cells.

14 SOLAR ENERGY↗
DOE OSTI2025

A surprising proliferation of detwinning in β -tin at extreme loading rates

Integrating data from dynamic compression experiments of condensed matter across three national laboratories has led to insight and quantitative calibration of materials strength over decades of loading rate. For many materials, a single strength model (such as PTW) is sufficient to capture the flow-stress strain rate relationship which is monotonic. Here, we show here that β -tin, a tetragonal metal, exhibits dramatic deviations from this behavior. Naive fitting to a single PTW model is insufficient to capture the behavior; indeed, such resulting inferred flow stress versus strain exhibits a non-monotonic behavior. We suggest a resolution to this by proposing that in β -tin there are important Bauschinger effects arising from favorable conditions for twinning and detwinning. A simple yield surface model when paired with PTW hardening captures the experimental data.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Pseudo-halide anion engineering for efficient quasi-2D Ruddlesden-Popper tin perovskite solar cells

Quasi-two-dimensional (2D) organic-inorganic hybrid tin perovskites have emerged as promising alternatives to lead-based perovskites in thin-film photovoltaics because of their reduced toxicity and improved stability. However, the undesired small n-value 2D phases and disordered crystal orientation enormously restrict the efficiency of quasi-2D tin perovskite solar cells (PSCs) due to uncontrollable nucleation and crystal growth processes. Here, we propose a mixed pseudo-halide anion engineering approach by using acetate (Ac - ) and tetrafluoroborate (BF 4 - ) anions to make quasi-2D Ruddlesden-Popper perovskites with a target formula of PEA 2 FA 4 Sn 5 I 16 . We find that the mixed Ac - and BF 4 - anions can not only promote homogeneously distributed PEA + cations in the precursor by effectively breaking the PEA + ···PEA + stacking but also retard the crystallization process by coordinating with unbonded SnI 2 , thereby, significantly reducing small n-value 2D phases, improving the crystal orientation, and suppressing the Sn 2+ oxidation. The resulting PSC exhibits up to 9% power conversion efficiency and 400 h stability.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Air-Stable Room-Temperature Quasi-2D Tin Iodide Perovskite Microlasers

Quasi-2D tin iodide perovskites (TIPs) are promising lead-free alternatives for optoelectronic applications, but achieving stable lasing remains challenging due to their limited environmental stability. Here, we report air-stable, room-temperature lasing from quasi-2D TIP microcrystals as small as 4 μm. Incorporation of the organic spacer 5IPA3 significantly enhanced the stability of these materials compared with previously reported TIPs. Lasing was observed from both dielectric (n = 4) and plasmonic (n = 3 and n = 4) TIP microlasers. Under picosecond pumping, lasing was sustained for over 108 pump pulses in ambient conditions. These results represent a significant step toward practical photonic applications of tin-based perovskites.

crystals↗
DOE OSTI2016

Fabrication of efficient low-bandgap perovskite solar cells by combining formamidinium tin iodide with methylammonium lead iodide

Mixed tin (Sn)-lead (Pb) perovskites with high Sn content exhibit low bandgaps suitable for fabricating the bottom cell of perovskite-based tandem solar cells. In this work, we report on the fabrication of efficient mixed Sn-Pb perovskite solar cells using precursors combining formamidinium tin iodide (FASnI 3 ) and methylammonium lead iodide (MAPbI 3 ). The best-performing cell fabricated using a (FASnI 3 ) 0.6 (MAPbI 3 ) 0.4 absorber with an absorption edge of ~1.2 eV achieved a power conversion efficiency (PCE) of 15.08 (15.00)% with an open-circuit voltage of 0.795 (0.799) V, a short-circuit current density of 26.86(26.82) mA/cm 2 , and a fill factor of 70.6(70.0)% when measured under forward (reverse) voltage scan. In conclusion, the average PCE of 50 cells we have fabricated is 14.39 ± 0.33%, indicating good reproducibility.

14 SOLAR ENERGY↗
DOE OSTI2011

Emissivity measurements of shocked tin using a multi-wavelength integrating sphere

Pyrometric measurements of radiance to determine temperature have been performed on shock physics experiments for decades. However, multi-wavelength pyrometry schemes sometimes fail to provide credible temperatures in experiments, which incur unknown changes in sample emissivity, because an emissivity change also affects the spectral radiance. Hence, for shock physics experiments using pyrometry to measure temperatures, it is essential to determine the dynamic sample emissivity. The most robust way to determine the normal spectral emissivity is to measure the spectral normal-hemispherical reflectance using an integrating sphere. In this paper we describe a multi-wavelength (1.6–5.0 μm) integrating sphere system that utilizes a “reversed” scheme, which we use for shock physics experiments. The sample to be shocked is illuminated uniformly by scattering broadband light from inside a sphere onto the sample. A portion of the light reflected from the sample is detected at a point 12° from normal to the sample surface. For this experiment, we used the system to measure emissivity of shocked tin at four wavelengths for shock stress values between 17 and 33 GPa. The results indicate a large increase in effective emissivity upon shock release from tin when the shock is above 24–25 GPa, a shock stress that partially melts the sample. We also recorded an IR image of one of the shocked samples through the integrating sphere, and the emissivity inferred from the image agreed well with the integrating-sphere, pyrometer-detector data. Here, we discuss experimental data, uncertainties, and a data analysis process. We also describe unique emissivity-measurement problems arising from shock experiments and methods to overcome such problems.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2012

Structural characterization and electronic structure of laser treated TiN thin film

TiN thin films prepared by laser treatment using Kr-F excimer laser in the controlled atmosphere. The depth distribution and composition of nitrogen and contaminated oxygen have been determined by non-Rutherford proton backscattering using 1.7 MeV Tendetron accelerator. The electronic structure of TiN thin film have been characterized by resonant photoelectron spectroscopy using indus-I synchrotron radiation. Specifically, complex resonance profile that shows the enhancement at 45 eV which is consistent with the resonant photoemission of Ti 3d states involved in the Titanium nitride and oxide.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Crystalline to amorphous phase transition of tin oxide nanocrystals induced by SHI at low temperature

Tin oxide (SnO{sub 2}) thin films were deposited using pulsed laser deposition (PLD) technique on Si substrates. The as-deposited films were irradiated using 100 MeV Ag ions at different fluences ranging from 3x10{sup 13} to 3x10{sup 14} ions/cm{sup 2} at an incidence angle of 75 deg. with respect to surface normal at liquid nitrogen (LN2) temperature. The as-deposited and irradiated films have been characterized using X-ray diffraction (XRD) and atomic force microscopy (AFM) techniques to study the modifications in structural and surface morphological properties. Nanocrystalline film become completely amorphous and nanograins of tin oxide disappeared from the surface as indicated by XRD spectra and AFM micrographs respectively.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Effect of oxidizer on grain size and low temperature DC electrical conductivity of tin oxide nanomaterial synthesized by gel combustion method

Nanocrystalline Tin oxide material with different grain size was synthesized using gel combustion method by varying the fuel (C{sub 6}H{sub 8}O{sub 7}) to oxidizer (HNO{sub 3}) molar ratio by keeping the amount of fuel as constant. The prepared samples were characterized by using X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Energy Dispersive Analysis X-ray Spectroscopy (EDAX). The effect of fuel to oxidizer molar ratio in the gel combustion method was investigated by inspecting the grain size of nano SnO{sub 2} powder. The grain size was found to be reduced with the amount of oxidizer increases from 0 to 6 moles in the step of 2. The X-ray diffraction patterns of the calcined product showed the formation of high purity tetragonal tin (IV) oxide with the grain size in the range of 12 to 31 nm which was calculated by Scherer's formula. Molar ratio and temperature dependence of DC electrical conductivity of SnO{sub 2} nanomaterial was studied using Keithley source meter. DC electrical conductivity of SnO{sub 2} nanomaterial increases with the temperature from 80K to 300K. From the study it was observed that the DC electrical conductivity of SnO{sub 2} nanomaterial decreases with the grain size at constant temperature.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2014

Should muffin tin radius vary in different structures of a material?: A case study

Quantum mechanical calculations based on density functional theory and a generalized gradient approximation (GGA) have been used to study the structural properties of YbN. Its predicted unit cell lattice parameter in NaCl (B1) structure is 4.7810Å and in CsCl (B2) structure it is 2.8685Å. In the determination of lattice parameter the muffin tin radius (R{sub MT}) of constituent atoms play important role. In both the structures the muffin tin radius for Yb and N converges to 2.3 and 1.4 a.u., respectively.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Molybdenum as a contact material in zinc tin oxide thin film transistors

Amorphous oxide semiconductors are of increasing interest for a variety of thin film electronics applications. Here, the contact properties of different source/drain electrode materials to solution-processed amorphous zinc tin oxide (ZTO) thin-film transistors are studied using the transmission line method. The width-normalized contact resistance between ZTO and sputtered molybdenum is measured to be 8.7 Ω-cm, which is 10, 20, and 600 times smaller than that of gold/titanium, indium tin oxide, and evaporated molybdenum electrodes, respectively. The superior contact formed using sputtered molybdenum is due to a favorable work function lineup, an insulator-free interface, bombardment of ZTO during molybdenum sputtering, and trap-assisted tunneling. The transfer length of the sputtered molybdenum/ZTO contact is 0.34 μm, opening the door to future radio-frequency sub-micron molybdenum/ZTO thin film transistors.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Investigation of fluorine-doped tin oxide based optically transparent E-shaped patch antenna for terahertz communications

In this paper, a fluorine-doped tin oxide based optically transparent E-shaped patch antenna is designed and its radiation performance is analyzed in the 705 – 804 GHz band. As optically transparent antennas can be mounted on optical display, they facilitate the reduction of overall system size. The proposed antenna design is simulated using electromagnetic solver - Ansys HFSS and its characteristics such as impedance bandwidth, directivity, radiation efficiency and gain are observed. Results show that the fluorine-doped tin oxide based optically transparent patch antenna overcomes the conventional patch antenna limitations and thus the same can be used for solar cell antenna used in satellite systems.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

χ{sup (3)} measurements of axial ligand modified high valent tin(IV) porphyrins using degenarete four wave mixing at 532nm

Porphyrins and metalloporphyrins are unique class of molecules for Nonlinear Optical applications because of their unique structure of altering the central metal atom, large extended π-system, high thermal stability, tunable shape, symmetry and synthetic versatility Here, we report χ{sup (3)} Measurements of a simple phenyl porphyrins and its highvalent tin(IV) porphyrins with Bromination characterized by UV-Visible spectroscopic method. In this study, we employed the Degenerate Four Wave Mixing technique using forward Boxcar geometry with an Nd:YAG nano second pulsed laser as source and it was found that the tin(IV) porphyrin with Bromination exhibits good χ{sup (3)} value and figure of merit.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Accommodation of tin in tetragonal ZrO{sub 2}

Atomic scale computer simulations using density functional theory were used to investigate the behaviour of tin in the tetragonal phase oxide layer on Zr-based alloys. The Sn{sub Zr}{sup ×} defect was shown to be dominant across most oxygen partial pressures, with Sn{sub Zr}{sup ″} charge compensated by V{sub O}{sup ••} occurring at partial pressures below 10{sup −31 }atm. Insertion of additional positive charge into the system was shown to significantly increase the critical partial pressure at which Sn{sub Zr}{sup ″} is stable. Recently developed low-Sn nuclear fuel cladding alloys have demonstrated an improved corrosion resistance and a delayed transition compared to Sn-containing alloys, such as Zircaloy-4. The interaction between the positive charge and the tin defect is discussed in the context of alloying additions, such as niobium and their influence on corrosion of cladding alloys.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Electron beam induced growth of tin whiskers

We have investigated the influence of electron irradiation on tin whisker growth. Sputtered tin samples exposed to electron beam of 6 MeV energy exhibited fast whisker growth, while control samples did not grow any whiskers. The statistics of e-beam induced whiskers was found to follow the log-normal distribution. The observed accelerated whisker growth is attributed to electrostatic effects due to charges trapped in an insulating substrate. These results offer promise for establishing whisker-related accelerated life testing protocols.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Correlation between laser absorption and radiation conversion efficiency in laser produced tin plasma

The correlation between the laser absorption and the conversion efficiency (CE) for 13.5 nm extreme ultraviolet (EUV) light in a laser-produced tin plasma was investigated. The absorption rate α and the CE were measured simultaneously for a laser-pre-formed low-density tin target as a function of the time delay between the pre-pulse and the main laser pulse. A clear and positive correlation between α and CE was found with increasing delay time; however, the CE decreases rapidly at longer delay times. This result is partly attributed to a reduction in the absorption rate, but is mainly attributed to the self-absorption of EUV light in excessively long-scale plasmas.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Synchrotron characterization of functional tin dioxide nanowires

Wire-like crystals of tin dioxide were synthesized by a gas-transport technique. The wires, of mainly nanometric diameters, were characterized by spectroscopy and microscopy techniques with the use of highly brilliant and intense synchrotron radiation. We studied the influence of the surface chemical state and the oxygen vacancies on the atomic and electronic structure of the nanowires. The surface of the nanowires is covered by a few nanometers of tin suboxides. The lack of oxygen over the surface layers leads to specific sub-zone formation in a gap, as shown by synchrotron studies.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Electronegativity-dependent tin etching from thin films

The influence of a thin film substrate material on the etching of a thin layer of deposited tin (Sn) by hydrogen radicals was studied. The amount of remaining Sn was quantified for materials that cover a range of electronegativities. We show that, for metals, etching depends on the relative electronegativity of the surface material and Sn. Tin is chemically etched from surfaces with an electronegativity smaller than Sn, while incomplete Sn etching is observed for materials with an electronegativity larger than Sn. Furthermore, the amount of remaining Sn increases as the electronegativity of the surface material increases. We speculate, that, due to Fermi level differences in the material’s electronic structure, the energy of the two conduction bands shift such that the availability of electrons for binding with hydrogen is significantly reduced.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗