High-Quality Ultralong Sb2Se3 and Sb2S3 Nanoribbons on a Large Scale via a Simple Chemical Route

In-Sb Covalent Bonds over Sb2Se3/In2Se3 Heterojunction for Enhanced Photoelectrochemical Water Splitting

Antimony selenide is a promising P-type photocatalyst, but it has a large number of deep energy level defects, leading to severe carrier recombination. The construction of a heterojunction is a common way to resolve this problem. However, the conventional heterojunction system inevitably introduces interface defects. Herein, we employ in situ synthesis to epitaxially grow In2Se3 nanosheets on Sb2Se3 nanorods and form In-Sb covalent interfacial bonds. This petal-shaped heterostructure reduced interface defects and enhanced the efficiency of carrier separation and transport. In this work, the photocurrent density in the proposed Sb2Se3/In2Se3 photocathode is 0.485 mA cm-2 at 0 VRHE, which is 30 times higher than that of pristine Sb2Se3 and it has prominent long-term stability for 24 h without obvious decay. The results reveal that the synergy of the bidirectional built-in electric field constructed between In2Se3 and Sb2Se3 and the solid In-Sb interfacial bonds together build a high-efficiency transport channel for the photogenerated carriers that display enhanced photoelectrochemical (PEC) water-splitting performance. This work provides efficient guidance for reducing interface defects via the in situ synthesis and construction of interfacial bonds.

Unlocking the Potential of Nanoribbon-Based Sb2S3/Sb2Se3 van-der-Waals Heterostructure for Solar-Energy-Conversion and Optoelectronics Applications

High-performance nanosized optoelectronic devices based on van der Waals (vdW) heterostructures have significant potential for use in a variety of applications. However, the investigation of nanoribbon-based vdW heterostructures are still mostly unexplored. In this study, based on first-principles calculations, we demonstrate that a Sb2S3/Sb2Se3 vdW heterostructure, which is formed by isostructural nanoribbons of stibnite (Sb2S3) and antimonselite (Sb2Se3), possesses a direct band gap with a typical type-II band alignment, which is suitable for optoelectronics and solar energy conversion. Optical absorption spectra show broad profiles in the visible and UV ranges for all of the studied configurations, indicating their suitability for photodevices. Additionally, in 1D nanoribbons, we see sharp peaks corresponding to strongly bound excitons in a fashion similar to that of other quasi-1D systems. The Sb2S3/Sb2Se3 heterostructure is predicted to exhibit a remarkable power conversion efficiency (PCE) of 28.2%, positioning it competitively alongside other extensively studied two-dimensional (2D) heterostructures.

Embedded Integration of Sb2Se3 Film by Low-Temperature Plasma-Assisted Chemical Vapor Reaction with Polycrystalline Si Transistor for High-Performance Flexible Visible-to-Near-Infrared Photodetector

Flexible optoelectronics have garnered considerable interest for applications such as optical communication, motion capture, biosignal detection, and night vision. Transition-metal dichalcogenides are widely used as flexible photodetectors owing to their outstanding electrical and optical properties and high flexibility. Herein, a two-dimensional (2D) Sb₂Se₃ film-based one transistor-one resistor (1T1R) flexible photodetector with high photosensing current and detection ranges from visible to near-infrared was developed. The flexible 1T1R was fabricated using an efficient field-effect transistor platform with the 2D Sb₂Se₃ film directly deposited on the sensing region using a low-temperature plasma-assisted chemical vapor reaction. The photodetector could achieve a maximum I_photo/I_dark of 15,000 under white light with a power density of 26 mW/cm², in which the photodetector showed quick rising and falling response times of 0.16 and 0.28 s, respectively. The 2D Sb₂Se₃ film exhibits broadband absorption in the visible and IR regions, yielding an excellent photoresponse under laser illumination with different wavelengths. To investigate the flexibility and stability of the 1T1R photodetector, the photoresponses were measured under different bending cycles and curvatures, which maintained its functions and exhibited high stability under convex and concave bending at a curvature radius of 20 mm.

One dimensional MOSFETs for sub-5 nm high-performance applications: a case of Sb2Se3 nanowires

Low-dimensional materials have been proposed as alternatives to silicon-based field-effect transistor (FET) channel materials in order to overcome the scaling limitation. In the present research, gate-all-around (GAA) Sb₂Se₃ nanowire FETs were simulated using the ab initio quantum transport method. The gate-length (L_g, L_g = 5 nm) GAA Sb₂Se₃ FETs with an underlap (UL, UL = 2, 3 nm) could satisfy the on-state current (I_on) and delay time (τ) of the 2028 requirements for high performance (HP) applications of the International Technology Roadmap for Semiconductors (ITRS) 2013. It is interesting that the L_g = 3 nm GAA Sb₂Se₃ FETs with a UL = 3 nm can meet the I_on, power dissipation (PDP), and τ of the 2028 requirements of ITRS 2013 for HP applications. Therefore, GAA Sb₂Se₃ FETs can be a potential candidate scaling Moore's law downward to 3 nm.

The High Anisotropy of the Epitaxial Growth of the Well-Aligned Sb2Se3 Nanoribbons on Mica

One-dimensional semiconductor nanostructures, which are different from those of bulk materials, have attracted considerable interest in either scientific research or practical application. Herein, the Sb₂Se₃ nanoribbons have been successfully synthesized by the epitaxial growth process on mica using the rapid physical vapor deposition method. The density of the Sb₂Se₃ nanoribbons increased quickly when the temperature decreased, and finally, the nanoribbons connected to each other and formed a network structure even in film. These nanoribbons were all well aligned along the preferred direction that either is parallel to each other or forms 60° angles. Further structural investigation demonstrated that the Sb₂Se₃ nanoribbons grew along the [001] directions, which are aligned along the directions [11̅0] and [100] or [100] and [110] on the mica surface. Then, an asymmetric lattice mismatch growth mechanism causing incommensurate heteroepitaxial lattice match between the Sb₂Se₃ and mica crystal structure was suggested. Furthermore, a polarized photodetector based on the film with the well-aligned Sb₂Se₃ nanoribbons was constructed, which illustrated strong photosensitivity and high anisotropic in-plane transport either in the dark or under light. The incommensurate heteroepitaxial growth method shown here may provide access to realize well-ordered nanostructures of other inorganic materials and promote the anisotropic photodetector industrialization.

Facile synthesis of novel antimony selenide nanocrystals with hierarchical architecture by physical vapor deposition technique

Stoichiometric antimony selenide (Sb2Se3) nanocrystals have been successfully engineered by a facile physical vapor deposition method, employing a single precursor of polycrystalline Sb2Se3 charge in a closed quartz ampoule under high vacuum without any foreign seed or extraneous chemical elements. This work underscores the efficacy of the vapor deposition process and provides synthetic strategies to scale down bulk Sb2Se3 into novel nanostructures. The morphological evolution of the tailored architecture was examined on micro and nano size scales by scanning electron microscopy and high-resolution transmission electron microscopy. The intrinsic mechanism governing the nanostructure formation is revealed as layer-by-layer growth, related to the unique layered structure of Sb2Se3. The optical properties of the grown crystals were probed by UV–vis–NIR and photoluminescence tools. The band-gap values of the microfibers, nanorods, nanooctahedra and nanospheres estimated from UV–vis–NIR analysis are found to be 1.25, 1.47, 1.51 and 1.75 eV, respectively. Powder X-ray diffraction, energy-dispersive analysis by X-rays, X-ray photoelectron spectroscopy, Raman spectroscopy and photoluminescence studies confirmed the quality, phase purity and homogeneity of the as-grown nanostructures. The adopted physical vapor deposition method is thus shown to be a simple and elegant route which resulted in the enhancement of the band gap for the Sb2Se3 samples compared with their counterparts grown by chemical methods. This approach has great potential for further applications in optoelectronics.

Chemical Vapor Deposition Growth of High Crystallinity Sb2 Se3 Nanowire with Strong Anisotropy for Near-Infrared Photodetectors

Low-dimensional semiconductors have attracted considerable attention due to their unique structures and remarkable properties, which makes them promising materials for a wide range of applications related to electronics and optoelectronics. Herein, the preparation of 1D Sb₂ Se₃ nanowires (NWs) with high crystal quality via chemical vapor deposition growth is reported. The obtained Sb₂ Se₃ NWs have triangular prism morphology with aspect ratio range from 2 to 200, and three primary lattice orientations can be achieved on the sixfold symmetry mica substrate. Angle-resolved polarized Raman spectroscopy measurement reveals strong anisotropic properties of the Sb₂ Se₃ NWs, which is also developed to identify its crystal orientation. Furthermore, photodetectors based on Sb₂ Se₃ NW exhibit a wide spectral photoresponse range from visible to NIR (400-900 nm). Owing to the high crystallinity of Sb₂ Se₃ NW, the photodetector acquires a photocurrent on/off ratio of about 405, a responsivity of 5100 mA W^-1 , and fast rise and fall times of about 32 and 5 ms, respectively. Additionally, owing to the anisotropic structure of Sb₂ Se₃ NW, the device exhibits polarization-dependent photoresponse. The high crystallinity and superior anisotropy of Sb₂ Se₃ NW, combined with controllable preparation endows it with great potential for constructing multifunctional optoelectronic devices.

Thermochromism from Ultrathin Colloidal Sb2 Se3 Nanowires Undergoing Reversible Growth and Dissolution in an Amine-Thiol Mixture

Liquid-based thermochromics can be incorporated into an arbitrarily shaped container and provide a visual map of the temperature changes within its volume. However, photochemical degradation, narrow temperature range of operation, and the need for stringent encapsulation processes are challenges that can limit their widespread use. Here, a unique solution-based thermochromic comprising ultrathin colloidal Sb₂ Se₃ nanowires in an amine-thiol mixture is introduced. The nanowires undergo reversible growth and dissolution with repeated cycles of heating and cooling between 20 and 160 °C, exhibiting intense and contrasting color changes during these processes. Furthermore, the transition temperature in which a change in color first appears can be continuously tuned over a range larger than 100 °C by introducing controlled amounts of Sn²⁺ . The colloidal nanowire dispersion in the amine-thiol mixture retains its thermochromic properties over hundreds of temperature cycles, continuous heating at 80 °C over months, and shelf life of up to 2 years in an open container under ambient conditions. To illustrate its utility as a robust liquid thermochromic, the nanowire solution is coated onto standard filter paper and its uses as a rewritable surface by thermal scribing, as well as an inexpensive means of visualizing the temperature distribution of an anisotropically heated block are demonstrated.

Rodlike Sb2Se3 Wrapped with Carbon: The Exploring of Electrochemical Properties in Sodium-Ion Batteries

One-dimensional Sb₂Se₃/C rods are prepared through self-assembly by inducing anisotropy, and their corresponding sodium storage behaviors are evaluated, presenting excellent electrochemical performances with superior cycling stability and rate capability. Sb₂Se₃ delivers a high initial charge capacity of 657.6 mA h g^-1 at a current density of 0.2 A g^-1 between 2.5 and 0.01 V. After 100 cycles, the reversible capacity of Sb₂Se₃/C is still retained at 485.2 mA h g^-1. Even at a high rate current density of 2.0 A g^-1, the charge capacity is still retained at 311.5 mA h g^-1. Through the analysis of cyclic voltammetry and in situ electrochemical impedance spectroscopy, the in-depth understanding of high rate performances is explored effectively. Briefly, the sodium storage performance of Sb₂Se₃/C is observably enhanced, benefiting from the 1D structure and the introduction of a carbon layer with robust structure stability and conductivity.

High-performance photodetectors based on Sb2S3 nanowires: wavelength dependence and wide temperature range utilization

Photodetectors which can work at both low and high temperatures are very important for the development of practical optoelectronic devices. Many studies have shown that low-dimensional semiconductors have more advantages in optoelectronic applications than their bulk forms. Here, we report the preparation of high-quality Sb₂S₃ nanowires (NWs) by a sulphur-assisted vapour transport method. The corresponding individual Sb₂S₃ NW based photodetectors exhibit good photoresponse in a wide spectral range from about 300 to 800 nm. The optimal photoresponse values are measured under the illumination of a 638 nm laser at room temperature: a high current ON/OFF ratio of about 210, a spectral responsivity of 1152 A W^-1, a detectivity of 2 × 10¹³ Jones, and rise and fall times of about 37 ms, respectively. More importantly, the temperature dependence of the electrical conductivity of Sb₂S₃ shows three variation regions which can be attributed to the interaction between the carrier mobility and carrier concentration. The temperature dependence of the photoresponse of the photodetectors shows that they have good adaptability to temperature, and they worked very well at a wide temperature range from 8 to 420 K. Our results indicate that low-dimensional Sb₂S₃ crystals are promising candidates for new multifunctional optoelectronic devices.

Versatile Solution-Processed Synthesis of Two-Dimensional Ultrathin Metal Chalcogenides Following Frank-van der Merwe Growth

Two-dimensional (2D) ultrathin metal chalcogenides represent a class of promising materials for various applications thanks to attractive physicochemical properties. However, a reliable pathway for fabricating ultrathin metal chalcogenides nanosheets, regardless of the bulk crystals of their 3D counterparts, still remains a challenge. Herein, we present a versatile solution-processed template synthesis strategy, in which a single molecular-level precursor anneals to ultrathin single-crystal nanosheets with the aid of lattice-matching templates, following the Frank-van der Merwe growth mode and featuring high quality, low cost, scalability, and processability. Following this strategy, Sb₂S₃, MoS₂, and ZnS nanosheets are successfully prepared as representatives for materials whose bulk counterparts possess 1D, 2D, and 3D crystal structures, respectively, and the growth mechanism is confirmed by crystal mode analysis. As a proof-of-concept application, MoS₂ and Sb₂S₃ nanosheets are used for gas sensor and flexible photodetector applications, respectively, which exhibit excellent performance. The method can also be easily extended to other ultrathin nanosheets like single metals, metal oxide, metal nitride, and heterostructures.

Highly Anisotropic Sb2 Se3 Nanosheets: Gentle Exfoliation from the Bulk Precursors Possessing 1D Crystal Structure

2D materials, particularly those bearing in-plane anisotropic optical and electrical properties such as black phosphorus and ReS₂ , have spurred great research interest very recently as promising building blocks for future electronics. However, current progress is limited to layered compounds that feature atomic arrangement asymmetry within the covalently bonded planes. Herein, a series of highly anisotropic nanosheets (Sb₂ Se₃ , Sb₂ S₃ , Bi₂ S₃ , and Sb₂ (S, Se)₃ ), which are composed of 1D covalently linked ribbons stacked together via van der Waals force, is introduced as a new member to the anisotropic 2D material family. These unique anisotropic nanosheets are successfully fabricated from their polymer-like bulk counterparts through a gentle water freezing-thawing approach. Angle-resolved polarized Raman spectroscopy characterization confirms the strong in-plane asymmetry of Sb₂ Se₃ nanosheets, and photodetection study reveals their high responsivity and anisotropic in-plane transport. This work can enlighten the synthesis and application of new anisotropic 2D nanosheets that can be potentially applied for future electronic and optoelectronic devices.

Saturable absorption in one-dimensional Sb2Se3 nanowires in the visible to near-infrared region

One-dimensional (1D) free-standing nanowires are particularly important for carrier confinement in two dimensions, which provides a platform to explore the nonlinear optical phenomena at the nanoscale. In this Letter, we demonstrate saturable absorption in the resonant and above-bandgap excitations of both ns and fs pulses in 1D crystalline Sb₂Se₃ nanowires prepared by the facile hydrothermal method. Impressively, the average length of the nanowires extends to a few micrometers with a high aspect ratio of 300. The excited-state to ground-state absorption cross-section ratio in Sb₂Se₃ nanowires is ≈0.23, which suggests that they can be utilized as passive mode lockers.

Organometallically Anisotropic Growth of Ultralong Sb2Se3 Nanowires with Highly Enhanced Photothermal Response

Ultralong orthorhombic Sb2Se3 nanowires have been successfully fabricated via an alternative facile organometallic synthetic route from the reaction of triphenylantimony(III) with dibenzyldiselenide in oleylamine at 180-240 °C without any other additives. The formation and growth mechanism of the Sb2Se3 nanowires is intensively investigated, and it is found that the anisotropic growth of the nanowires with almost constant diameters is resulted from the synergistic effects of the intrinsic property of the orthorhombic crystal structure and the weak binding assistance of oleylamine, and the length of the nanowires can be elongated easily by increasing reaction time in the synthetic route. Moreover, the photothermal response of the Sb2Se3 nanowires is first evaluated under illumination of UV light (320-390 nm), and it is especially noted that the Sb2Se3 nanowires exhibit highly enhanced photothermal responses (more than two times the intensity) as compared to the bulk Sb2Se3. In addition, the Sb2Se3 nanowires show excellent light-to-heat performance, which is superior to that of the nanostructured titanium dioxide and silicon powder under the same conditions.

Vibrational properties and bonding nature of Sb2Se3 and their implications for chalcogenide materials

There is more to chemical bonding in chalcogenides than the shortest, strongest bonds, as revealed by microscopic quantum-chemical descriptors.

Antimony selenide (antimonselite, Sb₂Se₃) is a versatile functional material with emerging applications in solar cells. It also provides an intriguing prototype to study different modes of bonding in solid chalcogenides, all within one crystal structure. In this study, we unravel the complex bonding nature of crystalline Sb₂Se₃ by using an orbital-based descriptor (the crystal orbital Hamilton population, COHP) and by analysing phonon properties and interatomic force constants. We find particularly interesting behaviour for the medium-range Sb···Se contacts, which still contribute significant stabilisation but are much softer than the “traditional” covalent bonds. These results have implications for the assembly of Sb₂Se₃ nanostructures, and bond-projected force constants appear as a useful microscopic descriptor for investigating a larger number of chalcogenide functional materials in the future.

Diameter-controlled and surface-modified Sb₂Se₃ nanowires and their photodetector performance

Due to its direct and narrow band gap, high chemical stability, and high Seebeck coefficient (1800 μVK⁻¹), antimony selenide (Sb₂Se₃) has many potential applications, such as in photovoltaic devices, thermoelectric devices, and solar cells. However, research on the Sb₂Se₃ materials has been limited by its low electrical conductivity in bulk state. To overcome this challenge, we suggest two kinds of nano-structured materials, namely, the diameter-controlled Sb₂Se₃ nanowires and Ag₂Se-decorated Sb₂Se₃ nanowires. The photocurrent response of diameter-controlled Sb₂Se₃, which depends on electrical conductivity of the material, increases non-linearly with the diameter of the nanowire. The photosensitivity factor (K = I_light/I_dark) of the intrinsic Sb₂Se₃ nanowire with diameter of 80–100 nm is highly improved (K = 75). Additionally, the measurement was conducted using a single nanowire under low source-drain voltage. The dark- and photocurrent of the Ag₂Se-decorated Sb₂Se₃ nanowire further increased, as compared to that of the intrinsic Sb₂Se₃ nanowire, to approximately 50 and 7 times, respectively.

Bi2S3microspheres grown on graphene sheets as low-cost counter-electrode materials for dye-sensitized solar cells

In this work, we synthesized 3D Bi2S3 microspheres comprised of nanorods grown along the (211) facet on graphene sheets by a solvothermal route, and investigated its catalytic activities through I-V curves and conversion efficiency tests as the CE in DSSCs. Although the (211) facet has a large band gap for a Bi2S3 semiconductor, owing to the introduction of graphene into the system, its short-circuit current density, open-circuit voltage, fill factor, and efficiency were Jsc = 12.2 mA cm(-2), Voc = 0.75 V, FF = 0.60, and η = 5.5%, respectively. By integrating it with graphene sheets, our material achieved the conversion efficiency of 5.5%, which is almost triple the best conversion efficiency value of the DSSCs with (211)-faceted 3D Bi2S3 without graphene (1.9%) reported in the latest literature. Since this conversion-efficient 3D material grown on the graphene sheets significantly improves its catalytic properties, it paves the way for designing and applying low-cost Pt-free CE materials in DSSC from inorganic nanostructures.

ONE-POT SYNTHESIS OF Sb2Se3 NANOWIRES USING SELENIUM DIOXIDE AS THE SELENIUM PRECURSOR IN AIR AND THEIR CHARACTERIZATION

Orthorhombic phase of antimony triselenide ( Sb 2 Se 3) nanowires have been obtained by a facile and effective one-pot noninjection chemical route with controllable shape and size. The synthesis, which uses SeO 2 as the selenium precursor and can be conducted in air, is suitable for the larger-scale industrial synthesis of high-quality nanocrystals at low cost. The as-prepared nanocrystals were extensively characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). We believe that the method present here is a more straightforward and cost-effective route to prepare Sb 2 Se 3 nanocrystals with high quality. The band-edge positions of the Sb 2 Se 3 nanocrystals are studied by cyclic voltammetry (CV).

Urchinlike nanostructure of single-crystalline nanorods of Sb2S3 formed at mild reaction condition

Urchinlike nanostructure of well-defined Sb(2)S(3) crystals of 3-4 μm in length and 30-150 nm in diameter oriented along [001] direction have been produced at a mild reaction temperature of 90 °C from SbCl(3) and S-methyl 3-phenyldithiocarbazate [C(6)H(5)NHNHC(S)SMe] in ethylene glycol medium. During the reaction, the amorphous Sb(2)S(3) spheres of 1.4 μm in diameter were formed at early reaction stage and then crystalline nanorods were continuously grown at the surface of Sb(2)S(3) spheres while transforming their morphology into urchinlike structure. The urchinlike Sb(2)S(3) was composed of single-crystalline Sb(2)S(3) nanorods, belong to the orthorhombic phase with cell parameters a = 11.307 Å, b = 11.278 Å, c = 3.847 Å and absorbed the light up to 750 nm-wavelength region. The urchinlike Sb(2)S(3) architecture was applied to the photoelectrochemical cell.

A facile chemical conversion synthesis of Sb2S3 nanotubes and the visible light-driven photocatalytic activities

We report a simple chemical conversion and cation exchange technique to realize the synthesis of Sb2S3 nanotubes at a low temperature of 90°C. The successful chemical conversion from ZnS nanotubes to Sb2S3 ones benefits from the large difference in solubility between ZnS and Sb2S3. The as-grown Sb2S3 nanotubes have been transformed from a weak crystallization to a polycrystalline structure via successive annealing. In addition to the detailed structural, morphological, and optical investigation of the yielded Sb2S3 nanotubes before and after annealing, we have shown high photocatalytic activities of Sb2S3 nanotubes for methyl orange degradation under visible light irradiation. This approach offers an effective control of the composition and structure of Sb2S3 nanomaterials, facilitates the production at a relatively low reaction temperature without the need of organics, templates, or crystal seeds, and can be extended to the synthesis of hollow structures with various compositions and shapes for unique properties.

Controllable synthesis and electrochemical hydrogen storage properties of Sb₂Se₃ ultralong nanobelts with urchin-like structures

The controlled synthesis of one-dimensional and three-dimensional Sb(2)Se(3) nanostructures has been achieved by a facile solvothermal process in the presence of citric acid. By simply controlling the concentration of citric acid, the nucleation, growth direction and exposed facet can be readily tuned, which brings the different morphologies and nanostructures to the final products. The as-prepared products have been characterized by means of X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM and selected area electron diffraction. Based on the electron microscope observations, a possible growth mechanism of Sb(2)Se(3) with distinctive morphologies including ultralong nanobelts, hierarchical urchin-like nanostructures is proposed and discussed in detail. The electrochemical hydrogen storage measurements reveal that the morphology plays a key role on the hydrogen storage capacity of Sb(2)Se(3) nanostructures. The Sb(2)Se(3) ultralong nanobelts with high percentage of {-111} facets exhibit higher hydrogen storage capacity (228.5 mA h g(-1)) and better cycle stability at room temperature.

Self-standing nanoribbons of antimony selenide and antimony sulfide with well-defined size and band gap

Sub-10 nm semiconducting nanostructures are crucial for the realization of nanoscale devices. Fabrication of nanostructures at this scale with homogeneous properties is challenging. Using ab initio calculations, we show that self-standing ribbons of antimony selenide and antimony sulfide of width 1.1 nm exhibit well-defined bandgaps of 1.66 and 2.16 eV, respectively. Molecular dynamics studies show that these ribbons are stable at 500 K. The one-dimensional (1D) heterostructure of these nanoribbons (Sb(2)Se(3)/Sb(2)S(3)) along the [001] direction shows a straddling type behavior.

Microwave-assisted synthesis of Sb2Se3 submicron tetragonal tubular and spherical crystals

Sb(2)Se(3) submicron tetragonal tubes have been prepared by a microwave-assisted polyol method using antimony trichloride and sodium selenite as the Sb and Se precursors. Scanning electron microscopy (SEM) results showed a novel transformation of Sb(2)Se(3) microstructures from submicron tubes to submicron spheres during the microwave heating process. The potential growth mechanism has been investigated by analyzing the samples at different growth stages. Transmission electron microscopy (TEM) analyses confirmed that samples prepared under 10 min microwave heating possessed tetragonal tubular structure with lengths in the range of 10-30 microm, thicknesses in the range of 0.5-1 microm and wall thicknesses in the range of 100-200 nm. High-resolution TEM (HRTEM) and selected area electron diffraction (SAED) results revealed that Sb(2)Se(3) submicron tubes were single-crystalline along the [001] direction. The optical properties of Sb(2)Se(3) submicron tubes and submicron spheres were characterized by UV-vis diffuse reflectance spectroscopy, and the band gap (E(g)) derived to be 1.161 and 1.173 eV, respectively.

Simple colloidal synthesis of single-crystal Sb-Se-S nanotubes with composition dependent band-gap energy in the near-infrared

We report the first synthesis of high-quality binary and ternary Sb(2)Se(3-x)S(x) nanotubes across the entire compositional range from x = 0 to 3 via a simple, low-cost, colloidal synthetic method of injection of Sb(III)-complex solution into a hot paraffin liquid containing Se, S, or a mixture thereof. In contrast to the classic rolling mechanism, the modular formation of the reported nanotubes follows a four-stage self-seeding process: (i) amorphous nanospheres, (ii) short crystalline nanotubes growing out of relatively large amorphous nanospheres, (iii) long crystalline nanotubes attached to small amorphous nanospheres, and (iv) single-crystal nanotubes. The obtained single-crystal nanotubes have tunable composition, orthorhombic phase, well-defined rectangular cross sections, and growth direction along [001], as revealed by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and selected area electron diffraction studies. UV-vis-NIR absorption spectroscopy reveals that the optical bandgap energy of the Sb(2)Se(3-x)S(x) (0 < or = x < or = 3) nanotubes increases quadratically with the sulfur concentration x with these bandgap energies falling in the range from 1.18 to 1.63 eV at the red edge of the solar spectrum. The present study opens a new avenue to low-cost, large-scale synthesis of high quality semiconductor nanotubes with technological applications in solar energy conversion and also for a wide range of optical nanodevices operating in the near-infrared.

Microwave-assisted synthesis of Sb2Se3 submicron rods, compared with those of Bi2Te3 and Sb2Te3

Orthorhombic Sb(2)Se(3) submicron rods were prepared from antimony sodium tartrate and Se powder via a microwave-assisted chemical method. The products were characterized by x-ray powder diffraction (XRD), transmission electron microscope (TEM) and selected-area electron diffraction (SAED) techniques. The reaction mechanism and the morphology of the product were studied in detail in comparison with those in the syntheses of Bi(2)Te(3) and Sb(2)Te(3). The synthesis of Sb(2)Se(3) was based on the polyol reducing process and microwaves played an important role. The morphologies of the compounds were mainly determined by their inherent anisotropic crystal structures. The optical properties of as-prepared Sb(2)Se(3) were also characterized by UV-vis diffuse reflectance spectroscopy, and the bandgap (E(g)) can be derived to be 1.16 eV, which is suitable for applications in photovoltaic conversion.