Bismuth Sulfide Thin Films Research Articles

High-performance Bi2S3 photodetector based on oxygen-mediated defect engineering and its wafer-scale fast fabrication

Bi2S3 with a 2D van der Waals structure has attracted much attention due to its high conductivity, large absorption coefficient, and environmental friendliness. The preparation of tunable optoelectronic devices can be realized by exploiting and tuning Bi2S3 intrinsic defects. In this work, a simple and rapid method for the preparation of bismuth sulfide thin films and successfully prepare Bi2S3 with sulfur vacancies (Svac) (LA-Bi2S3) and oxygen passivated (Svac) (AP-Bi2S3) was presented. The defect state difference of the two devices leads to exhibit different optoelectronic properties. Under 638 nm and 1310 nm illuminations, the LA-Bi2S3 photodetectors exhibit responsivities of up to 2250 and 3.6 mA/W and detectivities of 1.69 × 1012 and 2.6 × 109 cm·Hz1/2 W−1, while the AP-Bi2S3 photodetectors have ultra-fast on/off speeds of 1 ms and 8 ms, and on/off ratio up to 3 × 103. The preparation method of the tunable optoelectronic devices gives a new avenue for defect tuning in metal sulfides and for the preparation and application of optoelectronic devices.

Degradation of Organic Dye Congo Red by Heterogeneous Solar Photocatalysis with Bi2S3, Bi2S3/TiO2, and Bi2S3/ZnO Thin Films

In this work, bismuth sulfide (Bi2S3) thin films were deposited by a chemical bath deposition (CBD) technique (called soft chemistry), while titanium dioxide (TiO2) nanoparticles were synthesized by sol–gel and zinc oxide (ZnO) nanoparticles were extracted from alkaline batteries. The resulting nanoparticles were then deposited on the Bi2S3 thin films by spin coating at 1000 rpm for 60 s each layer to create heterojunctions of Bi2S3/ZnO and Bi2S3/TiO2. These materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). The optical and contact angle analyses were undertaken by UV–Vis spectroscopy and a contact microscopy angle meter, respectively. The calculated band gap values were found to be between 1.9 eV and 2.45 eV. The Bi2S3 presented an orthorhombic structure, the TiO2 nanoparticles presented an anatase structure, and the ZnO nanoparticles presented a wurtzite hexagonal crystal structure. Furthermore, heterogeneous solar photocatalysis was performed using the Bi2S3, Bi2S3/ZnO, and Bi2S3/TiO2 thin film combinations, which resulted in the degradation of Congo red increasing from 8.89% to 30.80% after a 30 min exposure to sunlight.

Modulating the Structure and Optoelectronic Properties of Solution-Processed Bismuth-Based Nanocrystals.

Bismuth-based chalcogenides have emerged as promising candidates for next-generation, solution-processable semiconductors, mainly benefiting from their facile fabrication, low cost, excellent stability, and tunable optoelectronic properties. Particularly, the recently developed AgBiS2 solar cells have shown striking power conversion efficiencies. High performance bismuth-based photodetectors have also been extensively studied in the past few years. However, the fundamental properties of these Bi-based semiconductors have not been sufficiently investigated, which is crucial for further improving the device performance. Here, we introduce multiple time-resolved and steady-state techniques to fully characterize the charge carrier dynamics and charge transport of solution-processed Bi-based nanocrystals. It was found that the Ag-Bi ratio plays a critical role in charge transport. For Ag-deficient samples, silver bismuth sulfide thin films behave as localized state induced hopping charge transport, and the Ag-excess samples present band-like charge transport. This finding is crucial for developing more efficient Bi-based semiconductors and optoelectronic devices.

Substrate temperature effects on the structural, morphological and optical properties of Bi2S3 thin films deposited by spray pyrolysis: An experimental and first-principles study

Bismuth sulfide (Bi2S3) nanostructured films were deposited on glass substrates using a spray pyrolysis method. Herein, we present a study of the effect of substrate temperature (TS) on the structural, morphological, and optical properties of the prepared nanocrystalline thin films. X-ray diffraction (XRD) and Raman spectroscopy analyses revealed the formation of polycrystalline orthorhombic Bi2S3 films. The crystallite size and micro-strain of the films changed as the substrate temperatures was varied. Scanning electron microscopy (SEM) images show a compact and dense surface, with a uniform spatial distribution of nearly spherical grains. Energy-dispersive X-ray spectroscopy (EDS) studies confirm the prevalence of Bi and S elements in the films, being films deposited at a temperature of 400 °C sulfur deficient. The crystallite size increases from 18 to 22 nm when Ts varies from 400 °C to 300 °C. The optical band gap of the films was found to vary between 1.44 and 1.58eV, while a high absorption coefficient (>104 cm−1) was measured in the visible and near-infrared spectral ranges. These experimental results were compared with ab initio calculations performed in the framework of the density functional theory (DFT). The band structure and density of states (DOS) of the Bi2S3 compound reveal an n-type semiconductor with a direct gap of about 1.52 eV. Both experimental and theoretical results provide strong evidence that our bismuth sulfide thin films can be suitable materials for light-harvesting in solar cell devices.

Development of chitosan base PbBiS2 thin films for photovoltaic application

Novel poly-crystalline nature of chitosan (CS) based Lead Bismuth Sulphide (PbBiS2) thin films have been deposited at different deposition temperatures by chemical bath deposition (CBD), a lucid and low cost technique. Structural, optical and electrical properties of the films were investigated using X-ray diffraction (XRD), Energy dispersive analysis of X-ray (EDAX), Scanning Electron Microscopy (SEM), Spectrophotometry, Photoluminescence, Hall Effect and Current-Voltage (I-V) estimations. The films were identified to be polycrystalline with orthorhombic shape. The films exhibited a highly reflective surface with a metal appearance. The optical band differences on the films ranged from 2.22 to 1.97 eV. The negative nature of the Hall coefficients indicated that the majority of load-carrying materials were electrons. The intensity of the photo-luminescence emission was increased. Current-voltage measurements reported the semiconductor nature of the film. The prepared thin films are suitable for solar cell applications.

Self-Powered Thermoelectric Hydrogen Sensors Based on Low-Cost Bismuth Sulfide Thin Films: Quick Response at Room Temperature.

Thermoelectric (TE)-based gas sensors have attracted significant attention due to their high selectivity, low power consumption, and minimum maintenance requirements. However, it is challenging to find low-cost, environmentally friendly materials and simple device fabrication processes for large-scale applications. Herein, we report self-powered thermoelectric hydrogen (TEH) sensors based on bismuth sulfide (Bi2S3) fabricated from a low-cost Bi2S3 TE layer and platinum (Pt) catalyst. When working at room temperature, the monomorphic-type TEH sensor obtained an output response signal of 42.2 μV with a response time of 17 s at a 3% hydrogen atmosphere. To further improve device performance, we connected the patterned Bi2S3 films in series to increase the Seebeck coefficient to -897 μV K-1. For comparison, the resulting N tandem-type TEH sensor yielded a distinguished output voltage of 101.4 μV, which was greater than the monomorphic type by a factor of 2.4. Significantly, the response and recovery time of the N-tandem-type TEH sensor to 3% hydrogen were shortened to 14 and 15 s, respectively. This work provides a simple, environmentally friendly, and low-cost strategy for fabricating high-performance TEH sensors by applying low-cost Bi2S3 TE materials.

Improvement in Optoelectronic Properties of Bismuth Sulphide Thin Films by Chromium Incorporation at the Orthorhombic Crystal Lattice for Photovoltaic Applications.

By using the chemical bath deposition approach, binary bismuth sulphides (Bi2S3) and chromium-doped ternary bismuth sulphides (Bi2−xCrxS3) thin films were effectively produced, and their potential for photovoltaic applications was examined. Structural elucidation revealed that Bi2S3 deposited by this simple and cost-effective method retained its orthorhombic crystal lattice by doping up to 3 at.%. The morphological analysis confirmed the crack-free deposition, hence making them suitable for solar cell applications. Optical analysis showed that deposited thin films have a bandgap in the range of 1.30 to 1.17 eV, values of refractive index (n) from 2.9 to 1.3, and an extinction coefficient (k) from 1.03 to 0.3. From the Hall measurements, it followed that the dominant carriers in all doped and undoped samples are electrons, and the carrier density in doped samples is almost two orders of magnitude larger than in Bi2S3. Hence, this suggests that doping is an effective tool to improve the optoelectronic behavior of Bi2S3 thin films by engineering the compositional, structural, and morphological properties.

Structural influence of nitrogen adducts on the morphology of bismuth sulfide thin films

Structural influence of nitrogen adducts on the morphology of bismuth sulfide thin films

Simplified Route for Deposition of Binary and Ternary Bismuth Sulphide Thin Films for Solar Cell Applications

For photovoltaic applications, undoped and Ni2+ doped Bi2S3 thin films were chemically deposited onto glass substrates at room temperature. Elemental diffraction analysis confirmed the successful Ni2+ incorporation in the range of 1.0 to 2.0 at. %, while X-ray Diffraction analysis revealed that orthorhombic crystal lattice of Bi2S3 was conserved while transferring from binary to ternary phase. Scanning electron microscopy images reported homogeneous and crack-free morphology of the obtained films. Optoelectronic analysis revealed that the bandgap value was shifted from 1.7 to 1.1 eV. Ni2+ incorporation also improved the carrier concentration, leading to higher electrical conductivity. Resultant optoelectronic behavior of ternary Bi2−x NixS3 thin films suggests that doping is proved to be an effectual tool to optimize the photovoltaic response of Bi2S3 for solar cell applications.

Optoelectronic Properties of Bismuth Sulfide Thin Films Grown by PVD

Bismuth (III) sulfide thin films are prepared on glass substrates by physical vapor deposition technique. Then, the films are annealed at different temperatures from 150 to 350°C with nitrogen and nitrogen-sulfur atmospheres, respectively. The effect of annealing temperature on the optoelectronic properties is investigated. The layers were characterized using ultraviolet-visible spectroscopy, XRD, Raman spectroscopy, EDS analysis and Hall effect. The film annealed at 250°C in a nitrogen-sulfur atmosphere exhibited the best condition with an initial thickness of 106 nm and band gap of 1.37 eV. Also, Bismuthinite phase was obtained, close to the stoichiometry with 59.95 and 40.05 at % for bismuth and sulfur, respectively. The charge carrier concentration of 6.9x1019 cm-3 with a n-type conductivity, the resistivity of 0.19 Ω-cm, and mobility of 0.44 cm2V-1s-1 are obtained.

Study of copper bismuth sulfide thin films for the photovoltaic application

Due to a suitable band gap and high optical absorption in the visible spectrum, copper bismuth sulfide (CBS) has raised concern as one of the potential photovoltaic absorber materials. In this work, CBS thin films were prepared by co-evaporating metal bismuth and CuS materials in a vacuum system and following by an annealing process. Morphologies, compositions, structures, electrical and optical properties of CBS thin films were all investigated. Finally, a completed photovoltaic device based on CdS/CBS heterojunction was fabricated and an efficiency of 1.7% was obtained in the current states. All of those analyses indicated CBS thin films a kind of suitable absorber material for the photovoltaic application.

Effect of substrate temperature on the structural, morphological and optical properties of copper bismuth sulfide thin films deposited by electron beam evaporation method

Copper bismuth sulfide thin films were deposited at 200 °C, 300 °C, 400 °C and 500 °C on the glass substrates by electron beam evaporation method. X-ray diffraction study revealed that the copper bismuth sulfide films of single and mixed phases were formed as a function of substrate temperatures. Substrate temperature of 300 °C and 400 °C formed single phase Cu4Bi4S9 and Cu4Bi5S10 films respectively whereas substrate temperature of 500 °C formed mixed phases of Cu4Bi4S9 and Cu4Bi5S10 film. Crystallite size, dislocation density and microstrain of the films were modified by the various substrate temperatures. Surface morphology of the film Cu4Bi5S10 deposited at 400 °C examined by scanning electron microscopy showed the distribution of spherical shaped particles on the film surface. The presence of copper, bismuth and sulfur elements in the deposited films was confirmed using energy dispersive spectral studies. The calculated direct optical band gap energy of the films deposited at different substrate temperature varied from 1.47 to 1.64 eV and the absorption coefficient is in the order of 106 cm−1.

Deposition of Bi2S3 thin films from heterocyclic bismuth(III) dithiocarbamato complexes

Two heterocyclic dithiocarbamate complexes, tris-(piperidinedithiocarbamato)bismuth(III) (1) and tris-(tetrahydroquinolinedithiocarbamato)bismuth(III) (2) were synthesized and characterized by elemental analysis and thermogravimetric analysis. The structure of complex (1) was confirmed by single-crystal X-ray analysis. Both complexes were used as single source precursors for the deposition of bismuth sulfide thin films by aerosol assisted chemical vapour deposition (AACVD) at 350, 400, 450 °C and spin coating followed by thermal treatment at 350 °C, 400 °C and 450 °C. Both deposition methods, gave sulfur deficient polycrystalline films of bismuthinite. Scanning electron microscopy (SEM) images of the films showed morphology was dependent on the solvent mixture, temperature, precursor type and method of deposition. AACVD gave films with hexagonal nanoplatelets, leaf-like platelet, ribbon-like fibre, needle-like fibre morphologies. Films in the form of rods and interwoven nanowires were obtained from spin coating.

Annealing study and thermal investigation on bismuth sulfide thin films prepared by chemical bath deposition in basic medium

Bismuth sulfide thin films were prepared by chemical bath deposition using thiourea as sulfide ion source in basic medium. First, the effects of both the deposition parameters on film growth as well as the annealing effect under argon and sulfur atmosphere on as-deposited thin films were studied. The parameters were found to be influential using the Doehlert matrix experimental design methodology. Ranges for a maximum surface mass of films (3 mg cm−2) were determined. A well-crystallized major phase of bismuth sulfide with stoichiometric composition was achieved at 190 °C for 3 h. The prepared thin films were characterized using grazing incidence X-ray diffraction, scanning electron microscopy and energy-dispersive X-ray analysis. Second, the bandgap energy value was found to be 1.5 eV. Finally, the thermal properties have been studied for the first time by means of the electropyroelectric (EPE) technique. Indeed, the thermal conductivity varied in the range of 1.20–0.60 W m−1 K−1, while the thermal diffusivity values increased in terms of the annealing effect ranging from 1.8 to 3.5 10−7 m2 s−1.

Crystallized InBiS3 thin films with enhanced optoelectronic properties

In this paper, a one-step thermal evaporation approach was used for fabrication of indium bismuth sulphide thin films, and the synergetic effects of co-evaporation of two sources (indium granules and Bi2S3 powders) were investigated using different characterization techniques. X-ray diffraction (XRD) analysis confirmed the crystalline orthorhombic structure for the post-annealed samples. Surface roughness and crystal size of the obtained film samples were increased with increasing annealing temperatures. Analysis using X-ray photoelectron spectroscopy showed the formation of the InBiS3 structure for the obtained films, which is also confirmed by the XRD results. The optical absorption coefficient value of the annealed samples was found to be in the order of 105 cm−1 in the visible region of the solar spectrum. The optical band gap energy and electrical resistivity of the fabricated samples were observed to decrease (from 2.2 to 1.3 eV, and from 0.3 to 0.01 Ω–cm, respectively) with increasing annealing temperatures (from 200 to 350 °C), indicating the suitability of the prepared InBiS3 thin films for solar cell applications.

Effect of deposition temperature on structural, optical and electrical properties of copper bismuth sulphide (CuBiS2) thin films deposited by chemical bath deposition

Abstract The effect of deposition temperature on the structural, optical and electrical properties of copper bismuth sulphide (CuBiS2) thin films deposited by chemical bath deposition onto glass substrates at different deposition temperatures (40 °C, 50 °C, 60 °C and 70 °C) for 5 hours deposition time period was investigated. The obtained films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX) and optical absorption spectra. All deposited films were polycrystalline and had an orthorhombic structure. Their grain size had changed with deposition temperature and their compositions were nearly stoichiometric. The optical band gap value was decreased from 2.44 eV to 2.33 eV with increasing the film thickness. Electrical parameters such as mobility and type of electrical conduction were determined from the Hall effect measurements. They showed that the obtained films have n-type conductivity and mobility values of the copper bismuth sulphide (CuBiS2) films have changed with deposition temperature.

Synthesis and characterization of thermally evaporated copper bismuth sulphide thin films

Non-toxic copper containing chalcogenides are considered as promising alternate materials for the absorber layer in thin film solar cells and visible-light harvesting devices. In this paper, we reported synthesis of Cu3BiS3 thin films using a two-step thermal evaporation method for the first time. A Cu2S layer of 0.4μm thickness was firstly evaporated onto glass substrate at room temperature, followed by evaporation of a Bi2S3 layer of 0.8μm thickness. The Cu3BiS3 thin films were formed by thermally annealing and diffusing the two evaporated layers in a vacuum furnace. This method resulted in the improved crystallinity and phase purity of the grown Cu3BiS3 films. Effects of annealing temperature on different properties of the fabricated samples were investigated. The obtained low band-gap (1.45eV) and good optical properties such as low transmittance (10–30%) and reflectance (~10%) of the Cu3BiS3 films demonstrated it as a suitable material for the absorber layer of solar cells.

Effects of Na incorporation and plasma treatment on Bi2S3 ultra-thin layers

As-deposited bismuth sulfide thin films prepared by means of a chemical bath deposition were treated with argon AC plasma. In this paper, we present the results on the physical modifications which were observed when a pre-treatment, containing a solution of 1M sodium hydroxide, was applied to the glass substrates before depositing the bismuth sulfide. The bismuth sulfide thin films were characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, atomic force microscopy, UV–VIS, and electrical measurements. The XRD analysis demonstrated an enhancement in the crystalline properties, as well as an increment in the crystal size. The energy band gap value was calculated as 1.60eV. Changes in photoconductivity (σp) values were also observed due to the pre-treatment in NaOH. A value of σp=6.2×10−6 (Ωcm)−1 was found for samples grown on substrates without pre-treatment, and a value of σp=0.28 (Ωcm)−1 for samples grown on substrates with pre-treatment. Such σp values are optimal for the improvement of solar cells based on Bi2S3 thin films as absorber material.

Electrical, optical and structural properties of rod shaped Bi2S3 thin films deposited by dip technique

In the present paper, we have reported the room temperature growth of bismuth sulphide (Bi2S3) thin films by dip method and detailed characterization of these films. The films were deposited from a reaction bath containing bismuth nitrate, glycine and sodium thiosulphate. We have analyzed the structure, morphology, composition, optical and electrical properties of Bi2S3 thin films. X-ray diffraction pattern showed that the films were polycrystalline. From optical absorption spectra the band gap of the material is estimated to be 1.6 eV. The electrical conductivity is of the order of 10−6 (Ω cm)−1. Composition analyses by EDAX show that the films are nearly stoichiometric in composition.

Deposition and characteristics of bismuth sulfide thin films by an in situ chemical reaction process at room temperature: a facile and eco-friendly approach

Uniform, smooth and densely packed Bi2S3 thin films were prepared at room temperature by an in situ solution chemical reaction using bismuth nitrate as precursor in a form of thin solid film which was reacted with ammonium sulfide ethanol solution. Bi2S3 thin films both as-deposited and annealed at different temperatures were characterized by XRD, SEM, EDS, AFM, UV–Vis–NIR and LSV measurements. The thin films growth with deposition cycle numbers was investigated. The results showed that the as-deposited Bi2S3 thin films were almost amorphous and near to chemical stoichiometry. The annealing promoted crystallization to orthorhombic structure as well as crystal growth from very small particles to short-rod shaped nanocrystals. The optical band-gap energy was in the range of 1.34–1.69 eV depended on crystal size on films. The eight dip-cycles Bi2S3 films annealed at 300 °C had a better photoelectrochemical performance with photocurrent density of 5.03 mA/cm2 bias 0.5 V vs. Ag/AgCl reference electrode. This in situ deposition had an average deposited rate of 40 nm per cycle and a self-perfect function to grow smooth with increase of dip-cycle numbers.