Copper Tin Sulfide Research Articles

Graphene‐Encapsulated Copper tin Sulfide Submicron Spheres as High‐Capacity Binder‐Free Anode for Lithium‐Ion Batteries

AbstractSn‐based sulfides are potential anode materials for lithium‐ion batteries (LIBs); nevertheless, they typically suffer from poor cycle stability resulted from the huge volume variation during lithium‐ion insertion and extraction. Herein, we successfully fabricated the multiphase Cu2Sn3S7/Cu2SnS3/SnS2 (CTS) submicron spheres uniformly incorporated with reduced graphene oxide nanosheets (CTS@RGO). This binder‐free hybrid CTS@RGO paper exhibits favorable capacity retention as an anode of LIBs (965 mAh g−1 after 300 cycles at current density of 500 mA g−1), as well as better rate capability and high initial coulombic efficiency compared with that of a pristine CTS anode. The enhanced electrochemical performance can be ascribed to the introduction of graphene as a buffer to accommodate large volume changes and to maintain structural integrity of electrode.

Erazoite, a new copper tin sulfide from the El Guanaco gold deposit, Antofagasta Province, Chile

Erazoite, a new copper tin sulfide from the El Guanaco gold deposit, Antofagasta Province, Chile

Eco-friendly p-type Cu2SnS3 thermoelectric material: crystal structure and transport properties.

As a new eco-friendly thermoelectric material, copper tin sulfide (Cu2SnS3) ceramics were experimentally studied by Zn-doping. Excellent electrical transport properties were obtained by virtue of 3-dimensionally conductive network for holes, which are less affected by the coexistence of cubic and tetragonal phases that formed upon Zn subsitition for Sn; a highest power factors ~0.84 mW m−1 K−2 at 723 K was achieved in the 20% doped sample. Moreover, an ultralow lattice thermal conductivity close to theoretical minimum was observed in these samples, which could be related to the disordering of atoms in the coexisting cubic and tetragonal phases and the interfaces. Thanks to the phonon-glass-electron-crystal features, a maximum ZT ~ 0.58 was obtained at 723 K, which stands among the tops for sulfide thermoelectrics at the same temperature.

Copper tin sulfide (CuxSnSy) thin films evaporated with x = 3,4 atomic ratios: Influence of the substrate temperature and the subsequent annealing in sulfur

CuxSnSy thin films with thicknesses of 1.5μm and x atomic ratios ranging between 3 and 4 have been prepared by co-evaporation at substrate temperatures varied from 150°C to 450°C and at evaporated copper rates of 10⿿16nm/min. The evolution of the structural, chemical, optical and electrical properties as a function of the deposition conditions has been analyzed for the various samples as-grown and after annealing at 500°C in sulfur atmosphere. The layers prepared at Tsus⿤350°C have shown a mixture of hexagonal CuS and cubic Cu2SnS3 phases, which reacted by the annealing to give orthorhombic Cu3SnS4 (for rCu=10nm/min) or orthorhombic Cu4SnS4 (for rCu=16nm/min). The increment of the substrate temperature to 450°C allowed also the crystallization of orthorhombic Cu3SnS4, coexisting with a secondary CuS phase for rCu=16nm/min. The application of a chemical treatment in KCN solution has been effective to remove the copper sulfide excess in the samples. The orthorhombic Cu3SnS4 has evidenced a gap energy of 1.4eV and an electrical resistivity of 7.9ÿ10⿿4Ωcm, whereas the orthorhombic Cu4SnS4 has shown a lower gap energy of 1.2eV and a higher electrical resistivity of 8.2ÿ10⿿2Ωcm.

Formation of copper tin sulfide films by pulsed laser deposition at 248 and 355 nm

The influence of the laser wavelength on the deposition of copper tin sulfide (CTS) and SnS-rich CTS with a 248-nm KrF excimer laser (pulse length τ = 20 ns) and a 355-nm frequency-tripled Nd:YAG laser (τ = 6 ns) was investigated. A comparative study of the two UV wavelengths shows that the CTS film growth rate per pulse was three to four times lower with the 248-nm laser than the 355-nm laser. SnS-rich CTS is more efficiently ablated than pure CTS. Films deposited at high fluence have submicron and micrometer size droplets, and the size and area density of the droplets do not vary significantly from 248 to 355 nm deposition. Irradiation at low fluence resulted in a non-stoichiometric material transfer with significant Cu deficiency in the as-deposited films. We discuss the transition from a non-stoichiometric material transfer at low fluence to a nearly stoichiometric ablation at high fluence based on a transition from a dominant evaporation regime to an ablation regime.

Towards cost effective metal precursor sources for future photovoltaic material synthesis: CTS nanoparticles

Copper tin sulfide (CTS) is an emerging candidate for solar application due to its favorable band gap and higher optical absorption coefficient. Kuramite-Tetragonal Cu3SnS4 (CTS) monodisperse nanoparticles are prepared by hot injection technique involving cost effective sulfate metal precursor source. A protocol for controlled crystal structure has been demonstrated by variation of cationic Cu:Sn ratio. The crystal structure, size, phase purity, atomic composition, oxidation state and optical properties of the nanoparticles are confirmed from X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman, energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and UV–visible spectroscopy, respectively. Hexagonal shaped particles within the size distribution of 7–9nm with an optimal band gap of 1.28eV are obtained. XPS study shows the Cu1+, Sn4+ and S2− oxidation states. The effects of influential factors such as metal precursor ratio, metal precursor source, reaction time, heating rate and solvents have been demonstrated systematically on the synthesis of CTS nanoparticles. The plausible mechanism of the formation of CTS nanoparticles has been proposed. The obtained results provide new insight for applying CTS nanoparticles in photovoltaic applications.

Enhanced thermoelectric properties of earth-abundant Cu2SnS3 via In doping effect

Ternary copper tin sulfide (Cu–Sn–S) compounds have been investigated for decades as promising candidates of earth-abundant thin film solar cell absorbers. Cu2SnS3 is a representative member of this material system, and is highly expected to be a potential thermoelectric material by the first-principles calculations. In this work, Cu2SnS3 bulk materials were synthesized by the mechanical alloying (MA) combined with spark plasma sintering (SPS), and their crystal structures, electronic transport properties and enhanced thermoelectric performance were systematically investigated. We found that pristine Cu2SnS3 is a p-type thermoelectric material with a relatively high thermopower up to 300 μV/K and low thermal conductivity below 1.0 W/m K above 700 K. It revealed that In doping is an effective means to improve the electrical transport properties, which leads to a figure of merit (ZT) of Cu2Sn0.9In0.1S3 close to 0.6 at the relatively low temperature (773 K).

Ethylenediamine Processed Cu2SnS3 Nano Particles via Mild Solution Route

Copper tin sulphide nanoparticles have been prepared by solution growth technique at various ethylenediamine concentrations. Prepared samples have been characterized using x-ray diffraction, fourier transform infrared, Raman and scanning electron microscopy techniques. x-ray diffraction results revealed that the prepared samples are nanocrystalline in nature with tetragonal structure. Fourier transform infrared spectroscopy analysis results showed the presence of Cu-O, Sn-O and Sn-S vibrations in the wavenumber range between 450 and 620 cm-1. Vibrational symmetry of prepared samples have been analyzed using Raman spectroscopy. Scanning electron microscopy analysis indicated the formation of flower like nanocrystals for samples prepared at various Ethylenediamine concentrations.

Synthesis of reduced graphene oxide–copper tin sulphide composites and their photoconductivity enhancement for photovoltaic applications

Graphene-based composites are attractive to effectively tune the intrinsic properties of inorganic semiconductors. We report the first study of band gap tuning and photoconductivity enhancement of reduced graphene oxide–Cu2SnS3 (G–CTS) composite. A simple solvothermal route has been used to synthesize G–CTS with and without a complexing agent in the reaction mixture. Raman and FTIR studies confirm the formation of G–CTS and reduced graphene oxide–Cu2SnS3 by the addition of complexing agent ethylenediaminetetraacetic acid (G–CTS(E)) during synthesis. Powder X-ray diffraction reveals the formation of cubic CTS structure in both the composites. Scanning electron microscopy (SEM) study has revealed microbar and nanorod morphologies in the composites. The wide absorption of composites has been measured using absorption spectroscopy study. The band gaps of G–CTS and G–CTS(E) have been calculated using the absorption spectra and found to be 1.33 and 1.61 eV, respectively. This study confirms the suitability of G–CTS and G–CTS(E) for photovoltaic applications. Photoconductivity study reveals that G–CTS(E) generates 60 % more current than G–CTS.

Growth of Cu2SnS3 thin films by a two-stage process: structural, microstructural and optical properties

Copper tin sulfide (Cu2SnS3) thin films were grown by a two-stage process of sequential deposition of precursor layers CuS and SnS by chemical bath deposition technique followed by annealing in sulfur atmosphere. Two stacks of SnS–CuS thin films were prepared in which SnS thickness alone was varied keeping CuS film thickness fixed in an attempt to optimize SnS layer thickness to obtain Cu2SnS3 (CTS). The annealed films were characterized by studying their structural, microstructural and optical properties. X-ray diffraction analysis of the films obtained by annealing stack S-I revealed that they are multi-phase containing Cu2SnS3 and the secondary phases, Sn2Sn3 and Sn-rich CTS phase Cu2Sn3S7. Films obtained on annealing stack S-II resulted in monoclinic CTS phase with minor Cu2Sn3S7, tetragonal/cubic CTS phases. The direct optical band gap of monoclinic CTS phase is found to be 0.82 eV.

Copper tin sulfide (CTS) absorber thin films obtained by co-evaporation: Influence of the ratio Cu/Sn

Copper tin sulfide thin films have been grown on soda-lime glass substrates from the elemental constituents by co-evaporation. The synthesis was performed at substrate temperatures of 350°C and 450°C and different Cu/Sn ratios, adjusting the deposition time in order to obtain thicknesses above 1000nm. The evolution of the morphological, structural, chemical, optical and electrical properties has been analyzed as a function of the substrate temperature and the Cu/Sn ratio. For the samples with Cu/Sn⩽1, Cu2Sn3S7 and Cu2SnS3 have been observed by XRD. Increasing the Cu/Sn to 1.5, the Cu2SnS3 phase was the majority, being the formation completed at Cu/Sn ratio around 2. The increment of the substrate temperature leads to a change of cubic structure to tetragonal of the Cu2SnS3 phase. The chemical treatment with KCN was effective to eliminate CuS excess detected in the samples with Cu/Sn>2.2. The samples with Cu2SnS3 structure show a band gap energy increasing from 0.9 to 1.25eV and an electrical resistivity decreasing from 7∗10−2Ωcm to 3∗10−3Ωcm when the Cu/Sn atomic ratio increases from 1.5 to 2.2.

Composition-Dependent Crystal Phase, Optical Properties, and Self-Assembly of Cu–Sn–S Colloidal Nanocrystals

We demonstrate a robust protocol for preparing monodisperse copper–tin–sulfide (CTS) nanocrystals (NCs) of tunable composition and controlled crystal phase. We show that the crystal phase of CTS NCs is determined not only by the reactivity of chalcogenide precursors but also by the cation composition (Cu:Sn ratio) and identity of ligands bound to the NC surface. In contrast to previous studies, we demonstrate broad variation of the Cu:Sn ratio in the product NCs, in both directions from the stoichiometric Cu2SnS3 compound. Localized surface plasmon resonance in the CTS NCs was tuned by varying the Cu:Sn elemental ratio. This demonstrates that the doping level of such alloy semiconductor NCs can be manipulated by varying the cation composition. This result opens new possibilities for applying CTS and related materials for solution-processed photovoltaic devices, by taking advantage of controllable and variable doping. In addition, reversible gelation of colloidal CTS NCs in nonpolar solvents was observed a...

Investigation on the formation of copper zinc tin sulphide nanoparticles from metal salts and dodecanethiol

We present a study on the formation mechanism of copper zinc tin sulphide (CZTS) nanoparticles prepared from metal salts and 1-dodecanethiol in oleylamine. The nanoparticle sample exhibits two kinds of crystals, large ones with a size of about 70 nm and smaller ones with a diameter of about 25 nm. Analysis of the chemical composition of single nanoparticles revealed that the small nanoparticles consist of copper sulphide, while the larger ones are CZTS nanoparticles. A thorough investigation of the formation process of the nanoparticles revealed that the presence of the copper sulphide nanoparticles originates from the formation of copper sulphide nanoparticles in the initial nucleation step. These initial copper sulphide nanoparticles are converted to copper tin sulphide before the final CZTS nanoparticles are obtained.

Synthesis and Shape Control of Copper Tin Sulphide Nanocrystals and Formation of Gold–Copper Tin Sulphide Hybrid Nanostructures

Hexagonal prismatic Cu3SnS4 nanoparticles and nanorods were synthesized by a hot-injection procedure. Changing the reaction conditions leads to the formation of different shapes. When oleylamine is used as a solvent, hexagonal prismatic particles are obtained, while a reaction in octadecene results in the formation of nanorods. The growth process of copper tin sulphide starts with the formation of djurleite copper sulphide seeds. Their reaction with Sn4+ ions leads to the formation of Cu3SnS4. These Cu3SnS4 nanocrystals form Au-Cu3SnS4 hybrid nanostructures by reaction with gold seeds

Hydrazine processed Cu2SnS3 thin film and their application for photovoltaic devices

Copper tin sulfide (Cu2SnS3) was a potential earth abundant absorber material for photovoltaic device application. In this contribution, triclinic Cu2SnS3 film with phase pure composition and large grain size was fabricated from a hydrazine solution process using Cu, Sn and S as the precursors. Absorption measurement revealed this Cu2SnS3 film had a direct optical band gap of 0.88 eV, and Hall effect measurement indicated the film was p-type with hole mobility of 0.86 cm2/Vs. Finally Mo/Cu2SnS3/CdS/ZnO/AZO/Au was produced and the best device efficiency achieved was 0.78%. Also, this device showed improved device performance during ambient storage. This study laid some foundation for the further improvement of Cu2SnS3 solar cell.

Influence of Source - Substrate Distance of Cu<sub>4</sub>SnS<sub>4</sub> Thin Films Grown by Co-Evaporation

Copper tin sulphide (Cu4SnS4) thin films were prepared on glass substrates by the thermal co-evaporation technique by varying the source - substrate distance (SSD) in the range, 10 25 cm at a constant substrate temperature of 400°C. The influence of SSD on the chemical as well as physical properties of as-grown Cu4SnS4films was investigated. The EDS analysis revealed that the evaporated films are stoichiometric at a SSD of 20 cm. X-ray diffraction analysis confirmed the presence of Cu4SnS4phase in the layers following the orthorhombic crystal structure. The films showed a strong (311) peak as the preferred orientation. The evaluated crystallite size of the films decreased with the increase of SSD. From the SEM analysis, it was observed that needle like grains were distributed on the surface of the substrate and its size decreased with increasing SSD. The energy band gap was estimated using the optical transmittance data that varied in the range, 1.25 1.34 eV with the change of SSD.

Effect of annealing temperature on the properties of spray deposited Cu2 SnS3 thin films

Copper tin sulphide (Cu2SnS3), a promising solar cell absorber layer for thin film heterojunction solar cells, was grown onto soda-lime glass substrates by spray pyrolysis technique. The effect of annealing Cu2SnS3 (CTS) films in sulphur atmosphere at different annealing temperatures is investigated. From X-ray diffraction (XRD) and Raman spectra analysis, it is observed that the films exhibit polymorphism with tetragonal and monoclinic CTS phases. While the as-deposited films and the films annealed at 400 and 450 °C are found to contain tetragonal as well as monoclinic CTS phases, the films annealed at 500 °C are found to be mostly monoclinic CTS. The crystallite size is found to increase from 15 to 40 nm with increase of annealing temperature. From energy dispersive X-ray spectrometer (EDS) analysis, the films annealed at 400 and 450 °C are found to be near-stoichiometric Cu2SnS3. The direct optical band gap of CTS films with dominant tetragonal phase is found to be ∼1.10 eV, while that of films with dominant monoclinic phase is found to be 0.97 eV.

Formation of Cu2SnS3 thin film by the heat treatment of electrodeposited SnS–Cu layers

Thin films of copper tin sulfide (Cu2SnS3) were obtained by sulfurizing a stack of thin layers of Cu and SnS in nitrogen atmosphere. The film stack was obtained by the sequential electrodeposition of SnS and Cu. The Cu2SnS3 film was characterized for structural, morphological, composition, optical, spectroscopic, and electrical properties. The optimum condition for the formation of Cu2SnS3 was developed after testing different sulfurization temperatures. The films were polycrystalline with monoclinic structure which was confirmed by Raman and transmission electron microscopy analysis. The interplanar spacings estimated from the high resolution transmission electron microscopy images are 2.74, 2.19, and 2.06 A. The average crystallite size is 13 nm, and the band gap of the film is in the range of 1 eV. The surface chemical composition determined by X-ray photoelectron spectroscopy showed the Cu:Sn:S ratio as 1.9:1:2.85 which is close to the stoichiometric Cu2SnS3. The films are p-type, photosensitive, and the conductivity measured in dark was in the range of 4 × 10−3 Ω−1 cm−1. The comprehensive characterization presented in this paper will update the knowledge on this material.

Preparation and characterization of Cu2SnS3 ternary semiconductor nanostructures via the spray pyrolysis technique for photovoltaic applications

Thin films of Cu2SnS3 have been deposited by the spray pyrolysis technique. Various Sn/Cu molar ratios (from 0.0 to 1.0) were applied, which allowed the study of the copper tin sulfide phase. Structural, morphological and compositional analyses have been carried out using x-ray diffraction, field emission scanning electron microscopy and energy dispersive spectroscopy. The pure CuS thin film showed the covellite phase with hexagonal crystal structure, and with increasing the Sn/Cu molar ratio, the films grown were crystallized with triclinic Cu2SnS3 ternary phase. Optical measurement analysis showed that the deposited layers have a relatively high absorption coefficient (∼105 cm−1) in the visible spectrum, about one order of magnitude higher than in other published reports. Also these layers presented a reduction of about 1 eV in the values of band gap from 2.57 to 1.58 eV with an increment in the Sn/Cu molar ratio from 0.0 to 1.0. The electrical properties studies showed that all these samples are p-type semiconductors and the resistivity decreases with increasing the Sn/Cu molar ratio.

A ternary Cu–Sn–S cluster complex—(NBu4)[Cu19S28(SnPh)12(PEt2Ph)3

Reaction of a mixture of CuCl, PhSnCl(3) and PEt(2)Ph with S(SiMe(3))(2) in THF resulted initially in the unexpected synthesis of the ionic, mixed copper-tin sulfide cluster [Li(thf)(4)][Cu(19)S(28)(SnPh)(12)(PEt(2)Ph)(3)] in low yields. However, by adding NBu(4)Cl to the reaction solutions we were able to selectively synthesize the structurally similar cluster ion in (NBu(4))[Cu(19)S(28)(SnPh)(12)(PEt(2)Ph)(3)]. Structural characterization by single crystal X-ray analysis reveals that the cluster anions consist in principle of a copper sulfide core decorated by PhSn(3+) groups. Although additional phosphine ligands are attached to copper atoms the clusters possess an open 'Cu(3)S(3)' face mostly protected by the [Li(thf)(4)](+) and (NBu(4))(+) counterions in the crystal structure. The cluster (NBu(4))[Cu(19)S(28)(SnPh)(12)(PEt(2)Ph)(3)] displays near-infrared, temperature-dependent photoluminescence at ∼820-930 nm in the solid state, which is especially bright at temperatures below ∼100 K.