Bismuth Selenide Research Articles

Screen-printed film deposited using quasi 2-dimensional Bi2Se3 nanostructures for desalination membrane filler application

Chalcogenides and 2D graphene are the emerging materials being investigated rigorously as efficient membrane filler materials for recovering minerals from seawater and for desalination through recrystallization. In this work quasi-2-dimensional bismuth selenide (Bi2Se3) nanostructure synthesized by microwave-assisted solvothermal method - mixed in ethylene glycol is used as the ink for depositing screen-printed film (SPF). A laboratory-scale experiment univocally demonstrates the possibility of application of SPF as an efficient membrane filler material for desalination processes such as in direct contact membrane distillation (DCMD). Morphology and topography studies confirm the growth of homogeneous hexagonal micro structures with an edge-to-edge length of 20–40 µm with a thickness of ~ 2–3 µm respectively and elemental mapping studies confirm the growth of sodium chloride (NaCl) crystals over the Bi2Se3 SPF. Growth of different morphology of NaCl (20–40 µm) including the metastable (111) oriented NaCl depicts that Bi2Se3 film assists the efficient crystallization process and helps in retaining the morphology of NaCl crystals with an enhanced crystal growth rate of the order of 10−8–10−9 m/s. Interestingly, thermoelectric power measurement in these Bi2Se3 nanostructures with n-type carriers and with Seebeck coefficient value of − 98 μV/K around the room temperature open up a new possibility for a combined desalination membrane filler application along with thermoelectric (TEP) application where the waste heat used for desalination/membrane crystallization can also be harvested in the form of useful electrical energy.

Graphene-like ultrathin bismuth selenide nanosheets as highly stable anode material for sodium-ion battery

Sodium-ion batteries have high potential for next-generation battery system because of their cost-effective and similar energy-storage mechanism to lithium-ion batteries. However, the commercial graphite anode for lithium-ion batteries cannot be applied to sodium-ion batteries. The lower rate performance and poor cycling life of existing anode materials are major bottlenecks to prospective application in sodium-ion batteries. To address this issues, we synthesize a novel ultrathin Bi2Se3 layered nanosheets that enhance sodium-ion storage performance due to its stable graphene-like structure. Benefiting from the layered nanosheets morphology, as-prepared anode material exhibit excellent electrochemical performance, which can deliver an initial high capacity of 650 mA h g−1 (Na+ storage) at 0.1 A/g along with outstanding stability. The ultrathin Bi2Se3 layered nanosheets with a thickness of ~6 nm offer a large electrode-electrolyte contact interface due to its porous morphology. Ex-situ transmission electron microscopy analysis and electrochemical impedance spectroscopy measurement reveals the structural stability of bismuth selenide nanosheets during repeated sodium-ion insertion and extraction process. The superior electrochemical performance and unique graphene-like architecture of the layered bismuth selenide nanosheets offer a promising anode for commercial sodium-ion batteries.

Reduction in electrical resistivity of bismuth selenide single crystal via Sn and Te co-doping

The structural and thermoelectric transport properties of melt-grown Bi2Se3 single crystals are systematically investigated with the co-doping of Sn and Te in the temperature range 10–400 K. The powder X-ray diffraction and high-resolution X-ray diffraction studies confirm the hexagonal crystal structure with R3‾m space group. Images of the field emission scanning electron microscopy have shown crack-free smooth surface morphological features. Energy dispersive analysis of X-ray authorizes the chemical composition of elements in the samples. The degenerate semiconducting nature is observed in the entire series of samples with 6.8 times reduction in electrical resistivity for (Bi0.96Sn0.04)2Se2.7Te0.3 compared to the pristine Bi2Se3. The maximum ZT value of ∼0.32 is obtained for Bi2Se2.7Te0.3 single crystal at 400 K, about 7.4 times larger than that of Bi2Se3.

Promoting the energy storage capability via selenium-enriched nickel bismuth selenide/graphite composites as the positive and negative electrodes

Hybrid metal chalcogenides incorporating prolific redox-active transition metal selenides with optimized interactions are suitable candidates to boost the electrochemical properties of supercapacitors. The present study elaborates the design and application of selenium (Se)-enriched reduced graphene oxide hybridized heterostructured nickel bismuth selenide (RGO/Ni-Bi-Se) and bismuth selenide (RGO/Bi2Se3)-based electrode materials by a simple in-situ growth solvothermal reaction for advanced battery-type supercapacitors. Integrating the advantages of different components, good electrical conductivity of RGO and Se-enrichment induce a strong collaborative effect on redox reactions. The favourable structural and compositional features are not only desirable for the capacitive and rate performance enhancement but also for volume change mitigation during successive charge–discharge processes. The heterostructured RGO/Ni-Bi-Se delivers a boosted electrochemical behavior with an exceptional specific capacity (220.2 mAh g–1 at 1 A g–1) and good rate performance (54.8% capacity retention at 50 A g–1). The strong synergy between the Ni and Bi active components with multielectron reversible Faradic redox reactions optimizes the overall electrochemical performances and modifies the charge storage capability of the electrode material. The interconnected porous nanoarchitectures are regulated with abundant interface engineering and disorders, thereby achieving a large electrode/electrolyte area at junction and shortening the ion diffusion paths as well as accelerating the electron-transmission ability during operation. On the other hand, the as-obtained RGO/Bi2Se3 negative electrode material exhibits better pseudocapacitive properties with favourable reversibility and displays a large specific capacitance of 464 F g–1 at 1 A g–1. The RGO fabric not only offers a solid skeleton for the self-assembly of building units but also enlarges the specific area for more electrochemical active sites and decreases the charge transfer resistance. The formation of weak electronegative Se is profitable to adjust the electronic configuration of exposed Ni/Bi sites. More significantly, the heterostructured RGO/Ni-Bi-Se reveals a well-matched performance with the capacitive RGO/Bi2Se3 and the established aqueous battery supercapacitor hybrid (BSH) device achieves admirable energy density of 62.3 Wh kg−1 at a power density of 949.7 W kg−1 together with 89.2% retention after 10 000 cycles.

First-principles calculations of electronic and optical properties of orthorhombic Bi2Se3 nano thin film

This study explored the electronic and optical properties of nano-thin film orthorhombic bismuth selenide (Bi2Se3) using first-principles approach. The thin films were modelled in the [001] direction using slab geometry supercell with vacuum along z-direction so that periodic images and slab can be managed independently. We obtained band gap of 0.730 eV, 0.566 eV and 0.690 eV for 1, 2 and 3 slabs respectively. It shows dependence of band structure to the thickness of the films. The reduced band gap in Bi2Se3 films is due to the effect of quantum confinement. The electron contributions were increased as the thickness of the thin film increased. We also found that the thickness of Bi2Se3 thin film influences its optical properties. Higher thickness provides higher static dielectric function, refractive index, extinction coefficient, absorption coefficient and loss function. This study demonstrates Bi2Se3 thin film has good optical properties that are useful for optoelectronic applications.

Superconductivity induced by Ag intercalation in Dirac semimetal Bi2Se3

In this paper we have investigated the physical and transport properties of Bismuth Selenide, (Bi2Se3) intercalated with Silver (Ag) (Gold (Au) is included for comparison) via dynamical mean field theory with local density approximation. The band structure of Bi2Se3 with a Dirac cone is strongly influenced by the intercalation phenomena at moderate densities which eventually leads to an orbital selective metal insulator transition leading to superconductivity at low temperatures. The claims on the orbital selectivity are substantiated by computing the density of states. While the onset of superconducting correlations at low temperatures are supported by a sudden drop in the resistivity as a function of temperature and the nature of susceptibility. Further the Fermi surface (FS) maps for low and high temperature yields no FS reconstruction.

All-Optical Probe of Three-Dimensional Topological Insulators Based on High-Harmonic Generation by Circularly Polarized Laser Fields.

We report the observation of an anomalous nonlinear optical response of the prototypical three-dimensional topological insulator bismuth selenide through the process of high-order harmonic generation. We find that the generation efficiency increases as the laser polarization is changed from linear to elliptical, and it becomes maximum for circular polarization. With the aid of a microscopic theory and a detailed analysis of the measured spectra, we reveal that such anomalous enhancement encodes the characteristic topology of the band structure that originates from the interplay of strong spin-orbit coupling and time-reversal symmetry protection. The implications are in ultrafast probing of topological phase transitions, light-field driven dissipationless electronics, and quantum computation.

Simple synthesis of multifunctional bismuth selenide nanoparticles; structural, optical characterizations and their effective antibacterial activity

Simple synthesis of multifunctional bismuth selenide nanoparticles; structural, optical characterizations and their effective antibacterial activity

Generation of spin-polarized hot electrons at topological insulators surfaces by scattering from collective charge excitations

Topological insulators (TIs) are materials which exhibit topologically protected electronic surface states, acting as mass-less Dirac fermions. Beside their fascinating fundamental physics, TIs are also promising candidates for future spintronic devices. In this regard, generation of spin-polarized currents in TIs is the first and most important step towards their application in spin-based devices. Here we demonstrate that when electrons are scattered from the surface of bismuth selenide, a prototype TI, not only the elastic channel but also the inelastic channel is strongly spin dependent. In particular collective charge excitations (plasmons) excited at such surfaces show a large spin-dependent electron scattering. Electrons scattered by these excitations exhibit a high spin asymmetry, as high as 40%. The observed effect opens up new possibilities to generate spin-polarized currents at the surface of TIs or utilize the collective charge excitations to analyze the electrons’ spin. The results are also important to understand the spin polarization of the photo-excited electrons excited at TIs surfaces. Moreover, our finding will inspire new ideas for using these plasmonic excitations in the field of spin-plasmonics.

Ultrafast Carrier-Lattice Interactions and Interlayer Modulations of Bi2Se3 by X-ray Free-Electron Laser Diffraction.

As a 3D topological insulator, bismuth selenide (Bi2Se3) has potential applications for electrically and optically controllable magnetic and optoelectronic devices. Understanding the coupling with its topological phase requires studying the interactions of carriers with the lattice on time scales down to the subpicosecond regime. Here, we investigate the ultrafast carrier-induced lattice contractions and interlayer modulations in Bi2Se3 thin films by time-resolved diffraction using an X-ray free-electron laser. The lattice contraction depends on the carrier concentration and is followed by an interlayer expansion accompanied by oscillations. Using density functional theory and the Lifshitz model, the initial contraction can be explained by van der Waals force modulation of the confined free carrier layers. Our theoretical calculations suggest that the band inversion, related to a topological phase transition, is modulated by the expansion of the interlayer distance. These results provide insights into the topological phase control by light-induced structural change on ultrafast time scales.

Morphology-dependent field emission investigations from the 2-dimensional Bi2Se3-RGO nanocomposites

The two-dimensional bismuth selenide (Bi2Se3)-reduced graphene oxide (RGO) nanocomposite have been synthesized by simple hydrothermal route for carrying out field emission (FE) studies. The Bi2Se3-RGO nanocomposite field emitters exhibit enhancement in the current densityas compared to pristine Bi2Se3emitter. The turn-on field for Bi2Se3-RGO nanocomposite field emitter decreases by ∼37% of its value for pristine Bi2Se3 emitters. The maximum current density observed from the Bi2Se3-RGO nanocomposite field emitter is ∼1000 µA/cm2 at an applied field of 6.0 V/μm. The influence of Se weight percentage in the Bi2Se3-RGO nanocomposite has been studied to understand the field emission behavior via morphological changes of the emitter surface. The Bi2Se3-RGO nanocomposite structure is thus seen as a prospective candidate for the development of efficient nanoscale field emission devices.

Low-temperature ultrafast optical probing of topological bismuth selenide

We report the optical response and temperature-dependent excited-state carrier dynamics in the flake of Bi2Se3, which is cleaved from its single crystal. The optical properties are explored using the visible-near infrared (VIS-NIR), infrared (IR), and photoluminescence (PL) spectroscopies. The VIS-NIR spectra are then used to find the Ɛ1 and Ɛ2 using Kramer’s Koning relations, confirming OBT of 2 eV and 1.4 eV. The DFT (density functional theory) calculations are also carried out to confirm the experimental optical transitions (OBT). To probe these OBT in the bismuth selenide, we have studied the temperature, fluence, and excitation dependent ultrafast transient reflectance over a wide spectral range from 2.58–0.77 eV (VIS-NIR) with different excitation energies 3.02 eV, 2.61 eV, 1.9 eV, and 1.4 eV to explore several previously unseen transitions that do not appear in PL spectroscopy and room temperature carrier analysis. The temperature-dependent excited-state dynamics are investigated at 5–300 K. This study clearly indicates the existence of Moss-Burstein shift in the visible region and Pauli blocking effect in the NIR region in the Bi2Se3 topological insulator. Moreover, the low-temperature TRUS confirms the transition to the second surface state present in bismuth selenide.

Reversible proton co-intercalation boosting zinc-ion adsorption and migration abilities in bismuth selenide nanoplates for advanced aqueous batteries

Rechargeable aqueous zinc-ion batteries present low-cost, safe, and environmentally-friendly battery technology but suffer from the limited choice of cathode materials because of the sluggish kinetics of divalent zinc-ion associated with the high adsorption and migration energy barrier. Herein, a reversible zinc/bismuth selenide mild aqueous system was demonstrated for the first time, where bismuth selenide nanoplate cathode delivers a high specific capacity of 263.2 mA h g−1 at 0.1 A g−1 and robust rate capability of 100.6 mA h g−1 even at 10 A g−1 with long-term lifespan (82.3% retention after 1000 cycles). Benefiting from the layered structure and nanoplate morphology of the bismuth selenide cathode, surface-dominated ion storage is verified by a quantitative kinetics analysis, particularly at high current rates. Notably, unlike conventional batteries with only the reversible intercalation of alkali ions into metal chalcogenides, zinc/bismuth selenide aqueous batteries possess a sequential proton and zinc-ion insertion/extraction process, identified by in situ synchrotron radiation-based X-ray diffraction. Density functional theory analysis approves the low adsorption energy and preferential embedding process of protons, and that can further optimize Zn2+ adsorption and migration abilities in bismuth selenide nanoplate, which is mainly responsible for the excellent performance.

Quantum coherence modulation in bismuth selenide topological insulator thin film by ion irradiation

The robust surface states of bismuth selenide (Bi2Se3) topological insulator (TI) that could potentially be harnessed for quantum computing and spintronics applications are often eclipsed by defect-induced bulk carriers. With the objective of suppressing the electronic transport in the bulk, we explore the effects of ion irradiation-driven isoelectronic doping in thin films of Bi2Se3 with 600 keV antimony (Sb+) ions at 45° oblique incidence. The distribution of Sb+ ions introduced into the system has been mapped using Rutherford backscattering spectroscopy. The heavy Sb+ ion irradiation has been observed to cause a change from parabolic magnetoresistance to linear magnetoresistance behavior in the irradiated films due to mobility fluctuations. Subsequent annealing in selenium environment has been found to reverse the damage produced by the irradiation, but with significant modifications in the quantum coherence signatures. Weak antilocalization behavior has been observed in the weak magnetic field limit and has been analyzed within the purview of the Hikami-Larkin-Nagaoka model. It has been found that the channel-separated Bi2Se3 film becomes completely channel-mixed due to the induced defects, yielding a system with a single coherent channel upon irradiation. In the as-deposited film, the temperature-dependent power law decay of the coherence length has been found to have two different exponents within the measured temperature range. On the other hand, the irradiated-annealed film has a single decay exponent which has been found to tend to − 0.5, indicating that electron-electron interaction is the only de-phasing mechanism involved. This work establishes the effectiveness of ion irradiation in tuning the quantum coherence phenomena in Bi-based TI systems.

Photothermal Killing of A549 Cells and Autophagy Induction by Bismuth Selenide Particles.

With a highly efficient optical absorption capability, bismuth selenide (Bi2Se3) can be used as an outstanding photothermal agent for anti-tumor treatment and shows promise in the field of nanotechnology-based biomedicine. However, little research has been completed on the relevant mechanism underlying the photothermal killing effect of Bi2Se3. Herein, the photothermal effects of Bi2Se3 particles on A549 cells were explored with emphasis put on autophagy. First, we characterized the structure and physicochemical property of the synthesized Bi2Se3 and confirmed their excellent photothermal conversion efficiency (35.72%), photostability, biocompatibility and ability of photothermal killing on A549 cells. Enhanced autophagy was detected in Bi2Se3-exposed cells under an 808 nm laser. Consistently, an elevated expression ratio of microtubule-associated protein 1 light chain 3-II (LC3-II) to LC3-I, a marker of autophagy occurrence, was induced in Bi2Se3-exposed cells upon near infrared (NIR) irradiation. Meanwhile, the expression of cleaved-PARP was increased in the irradiated cells dependently on the exposure concentrations of Bi2Se3 particles. Pharmacological inhibition of autophagy by 3-methyladenine (3-MA) further strengthened the photothermal killing effect of Bi2Se3. Meanwhile, stress-related signaling pathways, including p38 and stress activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK), were activated, coupled with the attenuated PI3K/Akt signaling. Our study finds that autophagy and the activation of stress-related signaling pathways are involved in the photothermal killing of cancerous cells by Bi2Se3, which provides a more understanding of photothermal materials.

Evolution of Topological Surface States Following Sb Layer Adsorption on Bi2Se3.

Thin antimony layers adsorbed on bismuth selenide () present an exciting topological insulator system. Much recent effort has been made to understand the synthesis and electronic properties of the heterostructure, particularly the migration of the topological surface states under adsorption. However, the intertwinement of the topological surface states of the pristine substrate with the Sb adlayer remains unclear. In this theoretical work, we apply density functional theory (DFT) to model heterostructures of single and double atomic layers of Sb on a bismuth selenide substrate. We thereby discuss established and alternative structural models, as well as the hybridization of topological surface states with the Sb states. Concerning the geometry, we reveal the possibility of structures with inverted Sb layers which are energetically close to the established ones. The formation energy differences are below 10 meV/atom. Concerning the hybridization, we trace the band structure evolution as a function of the adlayer-substrate distance. By following changes in the connection between the Kramers pairs, we extract a series of topological phase transitions. This allows us to explain the origin of the complex band structure, and ultimately complete our knowledge about this peculiar system.

Thermoelectric Characteristics of A Single-Crystalline Topological Insulator Bi2Se3 Nanowire.

The discovery of topological insulators (TIs) has motivated detailed studies on their physical properties, especially on their novel surface states via strong spin–orbit interactions. However, surface-state-related thermoelectric properties are rarely reported, likely because of the involvement of their bulk-dominating contribution. In this work, we report thermoelectric studies on a TI bismuth selenide (Bi2Se3) nanowire (NW) that exhibit a larger surface/volume ratio. Uniform single-crystalline TI Bi2Se3 NWs were successfully synthesized using a stress-induced growth method. To achieve the study of the thermoelectric properties of a nanowire (NW), including electrical conductivity (σ), Seebeck coefficient (S), and thermal conductivity (κ), a special platform for simultaneously performing all measurements on a single wire was designed. The properties of σ, S, and κ of a 200 nm NW that was well precharacterized using transmission electron microscope (TEM) measurements were determined using the four-probe method, the two-probe EMF across ∇T measurement, and the 3ω technique, respectively. The integrated TE properties represented by the figure of merit ZT (S2σT/κ) were found to be in good agreement with a theoretical study of Bi2Se3 NW.

Investigation of Structural and Thermoelectric Properties of Bismuth Selenide Thin Films

Background: Thermoelectric material with high performance and low cost is the basic need of today. Bismuth selenide is a thermoelectric material. A set of bismuth selenide thin films having different stoichiometry ratios varying Bi/Se ratio from 0.123 to 0.309 have been prepared. Objective: The present work deals with the synthesis and characterization of various thin films of bismuth selenide. The thermoelectric properties of thin films were also investigated. The aim of this work is to investigate the effect of composition ratio on the structural and thermoelectric properties and to find out the best stoichiometry ratio of bismuth selenide thin films that can be used in the application of thermoelectric devices. Methods:: A set of bismuth selenide thin films having different elemental compositions were prepared by employing the thermal evaporation technique. The crystal structure and elemental composition of thin films were investigated by XRD and EDAX, respectively. The roughness of films was analyzed by AFM. The thermoelectric properties of various thin films were also measured. Results: XRD spectrum confirms the formation of phases formed in thin films which slightly matched with standard data. AFM results indicated that the surface of films was smooth and nanoparticles were generated on the surface. AFM results indicated that the surfaces of annealed thin films were smoother than as-deposited thin films. Seebeck coefficient was found negative throughout the temperature range. The power factor was also calculated by the Seebeck coefficient and results revealed the effect of composition ratio on Seebeck coefficient, electrical conductivity, and power factor. Thin films having a composition ratio of 0.182 exhibited the highest power factor. Conclusion: This study provides relevant basic information on the thermoelectric property of thin films, as well as presents the effect of compositional variation on thermoelectric measurements. From the application point of view in the thermoelectric devices, the best stoichiometric thin films out of four prepared thin films have been presented.

Chemically Switchable n-Type and p-Type Conduction in Bismuth Selenide Nanoribbons for Thermoelectric Energy Harvesting.

Realizing switchable n-type and p-type conduction in bismuth selenide (Bi2Se3), a traditional thermoelectric material and a topological insulator, is highly beneficial for the development of thermoelectric devices and also of great interest for spintronics and quantum computing. In this work, switching between n-type and p-type conduction in single Bi2Se3 nanoribbons is achieved by a reversible copper (Cu) intercalation method. Density functional theory calculations reveal that such a switchable behavior arises from the electronic band structure distortion caused by the high-concentration Cu intercalation and the Cu substitution for Bi sites in the host lattice. A proof-of-concept in-plane thermoelectric generator is fabricated with one pair of the pristine n-type and intercalated p-type Bi2Se3 nanoribbons on a microfabricated device, which gives rise to an open-circuit voltage of 4.8 mV and a maximum output power of 0.3 nW under a temperature difference of 29.2 K. This work demonstrates switchable n-type and p-type electrical conduction in Bi2Se3 nanoribbons via a facile chemical approach and the practical application of nanoribbons in a thermoelectric device.

Potential thermoelectric materials of indium and tellurium co-doped bismuth selenide single crystals grown by melt growth technique

In the present work, the thermoelectric properties of potential thermoelectric materials (Bi1−xInx)2Se2.7Te0.3 grown as high-quality single crystals by the melt growth technique were investigated between 10 and 350 K. Powder X-ray diffraction confirms the hexagonal crystal structure of all studied crystals. The high-resolution X-ray diffraction study reveals the direction of growth, single-crystal quality, dislocation density, and the influence of dopants on the inner plane structure of the crystals. A clean surface with very low angle grain boundaries is observed by the field emission scanning electron microscopy. Energy-dispersive X-ray analysis confirms the elemental composition of the crystals. Electrical resistivity has shown degenerate semiconducting behavior with low activation energy. The Seebeck coefficient confirms p-type for the pristine and n-type conducting behavior for the doped samples, with the correlation to the carrier concentration and carrier mobility in the order of 1025/m3 and 10−4 m2/V s, respectively. Thermal conductivity has shown the dominant behavior of phonon scattering. A significant reduction in the electrical resistivity was found for the co-doped (Bi0.96In0.04)2Se2.7Te0.3 sample, leading to an enhancement of the power factor (PF) and thermoelectric figure of merit (ZT) by a factor of about 8.0 and 4.1, respectively, as compared to the pristine Bi2Se3 sample at 350 K. The highest ZT value of about 0.285 is achieved for (Bi0.96In0.04)2Se2.7Te0.3 at 350 K.