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Thickness dependent properties of chemically deposited Bi 2S 3 thin films
Abstract
Thin films of Bi2S3 with different thicknesses were prepared by the chemical deposition method from an aqueous acidic bath using thiosulfate as a sulfide ion source. The effect of film thickness on the optical, structural and electrical properties was studied. A shift of 0.6 eV in the optical bandgap energy, Eg, and a decrease in electrical resistivity from 2.8 × 104 to 5 × 103 Ω cm and an increase in grain size of Bi2S3 crystallites from 5.2 to 8.0 nm were observed when the thickness was varied from 52.7 to 220 nm. These changes are attributed to the quantum size effect in semiconducting films.
... Results obtained in previous works suggest that for optimal performance in heterojunction solar cells, the sensitizer should have an optical band gap in the range of 1-2.5 eV (Sun et al. 2008;Chen et al. 2011Chen et al. , 2012Kieven et al. 2008;Wang et al. 2012). Therefore, bismuth sulfide (Bi 2 S 3 ), a group V-VI, direct band gaps semiconducting materials of interest for solar cell application due to its large absorption coefficient and bulk band gap of 1.3 eV (Lokhande et al. 1997). Such ideal combination of properties of this material makes it one of the suitable semiconducting materials for photovoltaic applications as discussed by the Shockley and Queisser in respect of p-n homojunction solar cells (Shockley and Queisser 1961;Cademartiri et al. 2008;Yousefi et al. 2012). ...
... Chemical bath was prepared for Bi 2 S 3 using mixture of 0.01 M solution of bismuth nitrate [Bi (NO 3 ) 3 ] prepared in 1 M HNO 3 and 0.01 M aqueous solution of sodium thiosulphate [Na 2 S 2 O 3 ] as precursors for Bi 3? and S 2-, respectively (Lokhande et al. 1997). Ethylenediaminetetraacetic acid (EDTA) was used as a complexing agent to control the release of soluble species of Bi 3? in the sensitization bath. ...
... The deposition process was considered to be based on this slow release of Bi 3? and S 2ions in the solution which then condensed as ion by ion or cluster by cluster on the surface of substrate that was placed in the solution. It is well known that the deposition of Bi 2 S 3 occurs when the ionic product (IP) of Bi 3? and S 2exceeds the solubility product (Ksp = 10 -73 ) of the Bi 2 S 3 (Lokhande et al. 1997). After completing the desired reaction time of 10, 20, 30 and 40 min, the photoelectrodes were withdrawn from the bath and the corresponding photoanodes were named as P-10, P-20, P-30 and P-40, respectively. ...
This work deals with the sensitization of the porous TiO2 films of thickness about 4 µm deposited on fluorine-doped tin oxide with nanocrystalline Bi2S3 for photovoltaic application. The sensitization was achieved for four different sensitization times employing chemical solution deposition with bismuth nitrate and sodium thiosulphate as precursors for Bi3+ and S2−, respectively. The unsensitized and sensitized photoelectrodes were characterized using X-ray diffractometry, scanning electron microscopy and diffused reflectance spectroscopy. XRD patterns show the signatures of both anatase TiO2 and orthorhombic Bi2S3 in the sensitized photoanodes. However, crystallinity of Bi2S3 increased with increase in sensitization time from 10 to 40 min. The temporal effect of sensitization and annealing on the photovoltaic performance of the solar cells fabricated using four different photoelectrodes was studied using the photocurrent density versus photovoltage curves. Annealing apparently improved the photovoltaic performance of photoanodes. The best performance was obtained for cell fabricated using annealed TiO2/Bi2S3 photoanode after 30 min sensitization time showing V
oc ~ 0.37 mV, J
sc ~ 0.52 mA/cm2, FF ~ 68 and 0.43 %.
... Furthermore, a relationship between surface morphology and various deposition pressures was discovered. Using numerical simulations with the SCAPS-1D simulator, the impact of oxide layers on solar cell device performance was evaluated [36][37][38][39][40][41][42][43][44][45] . This allowed for the computational screening of oxide materials prior to experimental testing in a solar cell. ...
... There is a noticeable shift in the spectrum based on the deposition pressures. The combined impacts of disorder at grain boundaries, quantum size effect, and stoichiometric deviation might influence the transmission and absorbance of polycrystalline semiconductors 45 . The results are well aligned as reviewed [46][47][48][49][50][51][52] . ...
We report on the potential application of crystalline thin metal oxide films (TiOx, SnOx) with varying stoichiometries in perovskite solar cell devices. The oxides were deposited via reactive e-beam evaporation, involving the sublimation of pure metals under different pressures of pure oxygen, followed by thermal annealing at 200 °C. Variable angle spectroscopic ellipsometry, X-ray diffraction (XRD), contact angle measurements, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) were used to characterize the films. XRD findings confirmed the crystalline phases of SnOx thin films treated at 200 °C for the most oxygen-rich films (deposited at 2e-4 Torr), while TiOx layers exhibited an amorphous phase. FESEM results confirmed that uniform and dense films were generated across the entire substrate surface. Using the measured refractive indices in a computational model, it was demonstrated that optimizing the device design with these films could result in power conversion efficiencies surpassing 25%.
... This effect can be attributed to the quantum size effect, which is commonly observed in different semiconductors, 51-53 including bismuth sulfide. [54][55][56] Both the size and shape of the nanocrystals may affect the energy band gap of the material. According to quantum confinement theory, 57 the holes in the valence band and the electrons in the conduction band are confined by the potential barriers of the surface or the potential well. ...
... Aresti and co-workers 55 performed a theoretical analysis of the influence of Bi 2 S 3 nano-ribbon length on the energy gap shift. The thickness-dependent energy band gap of the Bi 2 S 3 thin layer was documented by Lokhande et al. 56 and attributed to the existence of a quantum size effect in the semiconducting film. ...
Bismuth sulfide (Bi2S3) is a chalcogenide semiconductor with a relatively narrow energy band gap that is promising for use in solar cells and photodetectors. This paper presents a highly efficient microwave synthesis of Bi2S3 submicrometric structures using poly(vinyl alcohol) (PVA) as a viscosity modification agent. The chemical composition, morphology, crystal structure, and optical properties of the prepared materials were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, and diffuse reflectance spectroscopy (DRS). The use of PVA in Bi2S3 synthesis resulted in a change in material morphology from microrods to nanosheets and a slight increase in the energy band gap from 1.34 eV to 1.43 eV. The Bi2S3 nanosheets were examined as photosensitive materials for the detection of visible light. High ON/OFF ratios of 66, 44, and 15 and large specific detectivities of 1.12x10^11 , 7.68x10^10 , and 6.43x10^10 Jones were achieved under blue (468 nm, 0.52 uW/cm2), green (517 nm, 0.95 uW/cm2), and red (628 nm, 0.13 uW/cm2) light illuminations, respectively. The photosensitive properties of Bi2S3 nanosheets were remarkable compared to that of many other photodetectors based on Bi2S3 micro-and nanostructures.
... The bandgap of Bi 2 S 3 is suitable for light harvesting; it is less toxic than PbS-and CdS-based sensitizers, the dispersibility of Bi 2 S 3 is good, and either powder or thin films can be synthesized. Various techniques are available for the synthesis of Bi 2 S 3 such as electrochemical deposition, [17] chemical bath deposition, [18] and successive ionic layer adsorption and reaction (SILAR) [19][20][21]. ...
... Comparative JV curves of various SILAR cycles(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) of Bi 2 S 3 /TiO 2 photoanode using C counter electrode ...
The synthesis of Bi2S3 nanoparticles for sensitizing TiO2 photoanodes were synthesized through a cost-effective and straightforward approach using modified chemical bath deposition (M-CBD) or successive ionic atomic layer adsorption reactions (SILAR) at room temperature. Initially, a TiO2 seed layer was synthesized at room temperature via the chemical bath deposition method, followed by deposition of a mesoporous TiO2 layer using the doctor blade method. This study investigated the influence of the number of SILAR cycles and the choice of counter electrodes on the performance of Bi2S3/TiO2-based photoelectrodes. Characterization of the prepared Bi2S3/TiO2 photoanode involved various techniques, including X-ray diffraction, UV–Vis spectroscopy, scanning electron microscopy, and Raman spectroscopy, enabling the analysis of its structural, optical, and morphological properties. The Bi2S3/TiO2-based cell exhibits a maximum conversion efficiency of 0.8%, demonstrating the potential of this combination for photovoltaic applications. This study contributes to the field of solar cell technology by presenting a novel approach for sensitizing TiO2 photoanodes with Bi2S3 nanoparticles, offering insights into the optimization of fabrication parameters and performance enhancement strategies for future device design and development.
... Bi 2 S 3 and Sb 2 S 3 are direct band gap materials. 80,81 Plots of the (ahn) n versus hn for n = 2 and 1/2 show a linear behaviour for n = 2, which confirms the presence of a direct transition in the Bi 2À2x Sb 2x S 3 samples for all compositions (Fig. S8, ESI †). Fig. S8, ESI † presents a Tauc plot to determine the band gaps for all Bi 2À2x Sb 2x S 3 samples. ...
... For the binary Bi 2 S 3 and Sb 2 S 3 compositions, the direct band gaps were found to be 1.66 and 2.19 eV, respectively; very close to the reported values for these materials. 3,35,[80][81][82][83] The values of the band gap for the mixed samples Bi 2À2x Sb 2x S 3 were estimated to be 1.72, 1.75, 1.88 and 2.08 eV for x = 0.2, 0.4, 0.6 and 0.8, respectively, values which lie between those of pure Bi 2 S 3 and Sb 2 S 3 ( Table 1). Fig. 9 represents the dependence of band gap of the Bi 2À2x Sb 2x S 3 samples on composition, demonstrating that the band gap of Bi 2À2x Sb 2x S 3 films increases from 1.66 to 2.19 eV with increasing Sb concentration. ...
Tris(O-ethylxanthate)bismuth(iii) (1) and tris(O-ethylxanthate)antimony(iii) (2) were synthesized and used as precursors for the preparation of Bi2-2xSb2xS3 alloys (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) using solventless thermolysis. The p-XRD peaks at all ratios corresponded well to an orthorhombic crystal structure between that of Bi2S3 and Sb2S3. The lattice parameters a and b were found to increase linearly as the Sb content increases in the Bi2-2xSb2xS3 samples, whereas c decreases gradually with increasing Sb. For all samples the elemental composition and uniform stoichiometry was determined by EDX analysis and ICP-OES. Incorporation of Sb into Bi2S3 led to an increase in the band gap from 1.66 eV at x = 0 to 2.19 eV at x = 1. The morphologies of the alloys were investigated using SEM, revealing different texturing as the composition changes from Bi2S3 to Sb2S3.
... Semiconductor nano crystallites prepared as powder or thin film form is of recent interest for many novel applications [1,2]. It is used as an n-type window layer material in thin film solar cells, and is a suitable candidate for photovoltaic applications [3]. ...
... It is observed that the grain size of CdSe can be tuned between 29 nm to 46 nm by varying the substrate temperature. Grain size was calculated using Debye-Scherrer's equation (1). ...
CdSe thin films were deposited on a glass substrate by using electron beam evaporation technique. The as deposited films were annealed from 100oC to 300°C with an increment of 100°C. Morphological, structural and optical characterization of the films was carried out by using scanning electron microscope (SEM), X-ray diffraction (XRD), ultraviolet-visible (UV-Vis) spectroscopy; and Fourier transform infrared spectroscopy. The X-ray diffraction pattern that the film has a cubic phase with preferred orientation (100), the grain size was found to be in the range of 29-46 nm. SEM results reveal that film grains are polycrystalline in nature covered the whole surface of the substrate.
... In each and every materials surface is exposed to various environment influences. When elements are burned in oxygen, they form compounds called oxides [1][2][3][4]. Transition metal chalcogenides are of current interest to energy related research due to semiconducting properties [1][2][3][4][5][6]. Metal oxides have numerous applications such as ceramics, chemical, gas, bio-sensors, actuators, IR and solar absorbers, pigments, photo detectors, optical switches, refractors, insulators, semiconductors, superconductors, super capacitors, transistors, ferroelectrics, magnets, anti-corrosion coatings, fuel cells, alkynes, lithium batteries and solar cells have been developed. ...
... When elements are burned in oxygen, they form compounds called oxides [1][2][3][4]. Transition metal chalcogenides are of current interest to energy related research due to semiconducting properties [1][2][3][4][5][6]. Metal oxides have numerous applications such as ceramics, chemical, gas, bio-sensors, actuators, IR and solar absorbers, pigments, photo detectors, optical switches, refractors, insulators, semiconductors, superconductors, super capacitors, transistors, ferroelectrics, magnets, anti-corrosion coatings, fuel cells, alkynes, lithium batteries and solar cells have been developed. ...
Our study delineates the optimal usage of high-quality Cu2O thin films in optoelectronic applications by analyzing film deposition and crystallographic structure when contolled by sputtering parameters such as temperature, oxygen flow rate and deposition time.
... Both MoOx and NiOx are recognized as naturally occurring ptype semiconductors that lack metal and exhibit distinct optical behaviors because of stoichiometric deviations resulting from various preparation techniques. Materials with optical band gap energy values exceeding 3 eV are appropriate for use as windows in solar energy conversion devices [31][32][33][34][35][36][37][38][39][40][41][42][43][44]. Oxide lms were grown in a reactive manner using e-beam evaporation in the study, by adjusting the oxygen ow rate, which correlates with the pressure inside the chamber. ...
We have developed crystalline thin metal oxide films (MoOx, NiOx) as hole transport layers with varying stoichiometries for perovskite solar cells applications. Reactive e-beam evaporation was employed to grow the oxides by vaporizing pure metals at different oxygen pressures, followed by thermal annealing at 200 °C. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, contact angle measurements, X-ray diffraction (XRD), and variable angle spectroscopic ellipsometry were used to analyze the grown films. The XRD findings confirm the presence of crystalline phases in the NiO x thin films when processed at 200 °C, particularly in the most oxygen-rich films (deposited at 2e-4 Torr). In contrast, the MoOx layers exhibit an amorphous phase. Field emission SEM results confirm the production of dense and homogeneous films across the substrate's surface, free from cracks and pinholes. A numerical model utilizing the measured refractive indices suggests that optimizing the device design with these thin films can achieve power conversion efficiencies of over 25%.
... Bi 2 S 3 is the semiconductor material whose bandgap energy (Eg=1.7 eV), lies in the visible energy spectrum and can be used in optoelectronic devices, particularly solar energy devices. Number of authors has worked on chemical deposition of Bi 2 S 3 thin films by using both aqueous and non-aqueous media Lokhande et al., 1997Garcia et al., 1991;Lokhande et al., 1988;Deshmukh et al., 1992;Mane et al., Acharya et al., 1986) ...
An overview of the chemical bath deposition technique for the growth of chalcogenide thin films for solar cell applications www.neuroquantology.com Abstract The ability of Chalcogenide materials to solve the stability and toxicity issues faced by conventional pervoskite solar cells is gaining increasing attention.Chalcogenide thin films belong to a special category of important materials because of their peculiar IR transparency and light-induced linear and non-linear optical property adjustments.Methods such as Electro deposition, chemical bath deposition, flash evaporation, spray pyrolysis, successive ionic layer adsorption and reaction, and so on have been used to prepare thin films.Chalcogenide products with absorption coefficients greater than 104 −1 and direct band gaps equivalent to 1.5 eV, such as cadmium telluride, copper indium gallium (di) selenide, and copper zinc tin sulphide, are desirable absorber materials for thin film solar cells and have been outlined in detail in this report. The chemical bath deposition method will be focused mainly in this review article.
... For example, most of the optoelectronic devices currently in use, particularly solar energy conversion and photovoltaic devices, could be modi¯ed accordingly. 1 The semiconductor nanocrystallites belong to the state of matter in the transition region between molecules and solids. Their physical and chemical properties are found to be strongly size-dependent. ...
Exploring the morphogical and structural properties along with gas sensing applications both pure and Ti-doped SnO2 ultra-thin films, were meticulously crafted on micromachined silicon substrate heater devices using a combination of classical soft chemical processes and hydrothermal techniques (SCPHTP). The fabrication process involved a two-step approach: initially, a 20nm layer of tin oxide was hydrothermally deposited onto the substrates, followed by annealing in wet air at 600∘C for 5h using a standardized temperature variation protocol. Subsequently, secondary layers with thicknesses of 20, 40 and 60nm were sequentially deposited onto the tin dioxide devices and oxidized in wet air at 550∘C and 600∘C for 20h each, using the same temperature modulation scheme. Throughout this process, the hydrothermal deposition temperature remained constant at 180∘C for both the initial and secondary layers of tin dioxide deposition. Additionally, Ti layers with thicknesses of 4 and 8nm were deposited onto the 20nm + 40nm system, subjected to annealing at 550∘C for 20h, followed by 1-min annealing in dry O2 at 700∘C and 800∘C, respectively, using a Rapid Thermal Annealing (RTA) system. Characterization of the crystalline and surface structures of the devices revealed a transformation of the soft chemical tin dioxide solution into the cassiterite structure of SnO2, resulting in uniform large surface areas for the sensor devices. Moreover, Ti metal layers of 4 and 8nm thicknesses were fully converted into TiO2 on the surface of the devices. Subsequent testing showcased higher current values in sandwich systems of 20nm + 60nm and 20nm + 40nm compared to the 20nm + 20nm configuration. Sensitivity and stability assessments for various volatile organic compounds (VOCs) and CO gases at a constant DC temperature of 400∘C indicated excellent performance, with sensitivity to CO gas being contingent on relative humidity (RH). Notably, RTA-annealed and Ti-8 nm-doped sensor devices exhibited superior sensitivity and reproducibility, particularly when treated at 800∘C in dry O2 for 1min. This heightened performance can be attributed to the occupation of chloride ions in the oxygen sites of the as-synthesized SnO2, resulting in enhanced sensing capabilities for VOC gases.
... The bandgaps obtained at 673 K (1.80 eV) and 723 K (1.78 eV) are near the optimal bandgap value for photovoltaic applications (Tiwari et al. 2013). The variation in E g can be impacted by the variation in the size of crystallites (Lokhande et al. 1997), the quantum size effect (Ilican et al. 2008), the reduction of stacking faults and crystal imperfections, and disorder at the grain boundaries (Kumar et al. 2012). ...
The stack of copper (Cu), tin (Sn), and sulfur (S) precursor layers was deposited on a Corning 2947 substrate using the thermal evaporation method under a vacuum of approximately 2 × 10–4 Pa, employing the sequentially evaporated layer deposition (SELD) technique. The as-deposited stack was annealed at 623–723 K under a vacuum of approximately 2 × 10⁻¹ Pa to achieve the Cu3SnS4 phase. The stack exhibits amorphous behaviour, while films grown between 623 and 723 K attain nanostructured Cu3SnS4 (CTS) form. The influence of TA on the characteristics of the Cu3SnS4 layers was investigated through structural, morphological, compositional, optical, and electrical analyses. The annealed CTS films crystallize in a tetragonal crystal system with the space group I42 m (121). The grown films exhibit granular structures, with particles synthesized at 673 K demonstrating increased size. The bandgap (Eg) of the films decreases from 2.13 eV to 1.78 eV, while the absorption coefficient (α) ranges from 1 × 10⁵ to 3 × 10⁵ cm⁻¹, as the annealing temperature (TA) increases from 623 to 723 K. At 673 K, the low resistivity of 9.37 × 10⁻³ Ω-cm, high mobility of 56.4 cm²/V-s, and acceptor concentration of 1.19 × 10¹⁹ cm⁻³ result from the increased crystallite size, which reduces grain boundary scattering. Thus, Cu3SnS4 is a promising absorber layer for thin-film solar cells due to its tunable bandgap, high optical absorption, low cost, and the use of earth-abundant elements. This study successfully advances photovoltaic technology by developing an economically viable alternative material for solar cell absorber layers, paving the way for large-scale solar cell production.
... Among the above various techniques of thin film preparation, we preferred chemical bath deposition, which is simple, economic, suited for a large area deposition and does not required for sophisticated instrument. Chemical deposition of Bi 2 S 3 thin films have reported earlier by many authors using different sulphide ion releasing sources such as thiosulfate, thiourea and thioacetamide [18][19][20][21][22][23]. Characterization of the as-prepared and annealed films of the undoped nanostructured Bi 2 S 3 thin films prepared by chemical bath deposition technique using thioacetamide (TAM) as sulphide ion source and triethanolamine (TEA) as complexing agent have reported in our earlier paper [24]. ...
Nickel (Ni+2) doped nanocrystalline Bi2S3 thin films are deposited on the glass substrate from the solutions containing Bismuth Nitrate, Ethylenediamine Tetraacetic acid (EDTA) and Thioacetamide at a bath deposition temperature of 318K. The optical, surface morphological and electrical properties of Ni-doped Bi2S3 thin films prepared at three different doping concentration are investigate by using ultraviolet–visible transmission spectra (UV–Vis), Scanning electron microscopy (SEM), Energy Dispersive X-ray (EDAX) and thermo-e.m.f. techniques. The optical band gap energies are found in between 2.32-2.43 eV. The SEM images show that the prepared films are continuous, dense and distributed over the entire area with good uniformity. The electrical conductivity of the films are in the order of 10-2 Ω-1 m-1 . The films are n-type as determined from the Hot Probe method. Photoconductivity studies reveal that photocurrent increases with the increase in Ni doping concentrations. Due to the absorption of photons, free electron-hole pairs (EHP) are produce.
... Preparation of semiconductor nano crystallites in the form of powder or thin film is of recent interest for many novel applications [1,2]. Such materials were used as an n-type window layer material in thin film solar cells, and is a much suitable candidate for photovoltaic applications [3]. ...
Crystalline CdSe thin films were prepared by using electron beam evaporation technique. The deposited particles on the glass substrate were annealed from 100º C to 300 oC insteps of 100 oC. The XRD patterns recorded for the film shows that they exhibit polycrystalline structure and were arranged in the hexagonal form. The X-ray diffraction pattern also shows that the film has a cubic phase with preferred orientation (100), and the grain size was found to be in the range of 29-46 nm. Optical studies show that it has direct band gap and has a clear morphology on the glass substrate. The optical studies of the films also revealed a greater transmittance.
... This is because with increase in precursor solution concentration, the strain and dislocation density are reduced [22]. Similar behaviour of crystallite size has been reported in literature [23,24]. The lattice parameter 'a' of CoFe 2 O 4 thin films for (311) plane was determined using the standard relation for cubic phase. ...
CoFe2O4 thin films have been prepared with various solution concentrations using chemical spray pyrolysis technique. The dependence of precursor solution concentration on physical and electrochemical properties of CoFe2O4 thin films has been studied. XRD study showed spinel cubic crystal structure symmetry. FESEM micrographs showed mesoporous, spherical grain-like surface morphology. EDAX analysis confirmed formation of stoichiometric CoFe2O4 thin films. CoFe2O4 thin films showed high absorption coefficient of 10⁴ cm⁻¹ with direct allowed type transition and bandgap energies in the range of 2.28–2.45 eV. The CoFe2O4 thin film prepared with 0.20 M solution concentration showed the lowest electrical resistivity of 2.63 × 10³ Ωcm and the activation energies in the range of 0.044–0.051 eV and 0.002–0.010 eV. The maximum specific capacitance of 593 Fg⁻¹ at scan rate of 5 mVs⁻¹ from CV and 628 Fg⁻¹ at a current density of 0.5 Ag⁻¹ from GCD were observed. The specific energy of 21.97 Whkg⁻¹ and specific power of 550 Wkg⁻¹ at current density of 2 Ag⁻¹ were observed for CoFe2O4 thin film prepared with 0.20 M solution concentration. Further, the CoFe2O4 thin film prepared with 0.20 M solution concentration exhibited 92.85% retention of its specific capacitance after 1000 continuous charge–discharge cycles at an applied current density of 1 Ag⁻¹. The electrochemical performance suggests the CoFe2O4 thin film as a potential electrode material for energy storage applications.
... For the other films, the band gap decreases from 2.47 down to 2.43 eV with increase of film thickness. Since the decrease in particle size causes the band gap increase and the decrease in thickness [44], this variation is [45,46]. Shah et al. [47] found that the lessening grain size causes a rise in the bandgap. ...
The objective of the present study is to provide the effect of immersion time and CO3²⁻ concentration on the structural and optical properties of CdS films. Chemical bath deposition was performed to prepare two sets of samples using two different solutions. The first set was prepared using a mixture of cadmium carbonate CdCO3, thiourea, ammonia, distilled water, and a few drops of dilute sulphuric acid. The obtained solution was milky due to the partial dissociation of cadmium carbonate. For the second set, the solution contains the same chemical composition with the difference in the amount of added acid to turn the chemical solution clear and transparent. Hexagonal CdS film structures were obtained with (002) preferred orientation for the first set of samples. The transmittance in the visible domain is between 76 and 92%, and the values of the gap energy are between 2.43 and 2.59 eV according to the deposition time. For the second set, the obtained CdS films have a cubic structure with (111) preferential orientation. The transmittance of the films was found to be between 38 and 80%, and the bandgap energy increased with immersion time from 2.18 to 2.32 eV.
... The small differences are inherent to the calculation or measuring errors. It is interesting to observe that the influence of various factors, such as structural parameters, grain size, the presence of impurities, the deviation in the stoichiometry, and lattice strain, has also been reported in the literature [47][48][49][50]. ...
The main aim of the paper to the synthesis of Mn (x)-doped NiCr 2 O 4 nanoparticles by varying Mn content (x = 0.00%, 0.01%, 0.02%, and 0.03%) by microwave method for correlating the effect of NiCr 2 O 4 on structural, optical, and magnetic properties of the materials. Understanding the optical, magnetic, and structural properties of huge reservoir factors has essential applications in various aspects of materials science. Our study is to relate the reduction of grain size of Mn content in NiCr 2 O 4 host material. The XRD results revealed that there was an apparent decrease in the characteristic peaks of Mn in the MnNiCr 2 O 4 nanostructure. Particularly, the peak position of (2 2 0) and (3 1 1) planes was decreased. This decrease in peak position is attributed to the creation of defects or disorders due to the Mn ions in the chromite lattice structure. This inter-site Mn cation migration is responsible for the breaking of long-range cation order and the introduction of defects at both the T-site and O-sublattices site simultaneously. Ó 2021 The Author(s). Published by Elsevier B.V. on behalf of King Saud University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
... The nanocrystalline Hg x Cr 2-x S 4 (x = 0.6) (HGS) thin films, have been of interest due their semiconducting nature and considerable application in the field of electronics and electro-optical devices [1,2] magneto-optical devices and in magnetocapacitive as well as magnetoelectric devices [3][4][5][6][7][8][9][10][11]. Based on this concept, intensive research has been performed in the past to study the synthesis and characterization of these thin films. ...
The ternary thin films of composite HgxCr2-xS4 (x = 0.6) have been deposited by simple chemical bath deposition (CBD) technique on glass substrate. The thin films have been deposited at optimized conditions pH at 10 0.1, bath temperature 650C, deposition time 120 minutes. The films were uniform and adherent to glass substrates. They were characterized by structural, optical, and electrical measurement techniques. According to their X-ray diffraction patterns HgxCr2-xS4(x = 0.6) films are crystalline with band gap of 2.4 eV. Scanning electron micrographs showed that the substrates were well covered with films no cracks or pinholes were observed. The electrical resistivity of the films is found to be 1.3703 x 103 Ω-cm to 2.1243 x 103 Ω-cm at temperature range 3030k to 4230K. According to thermoelectric power measurements HgxCr2-xS4(x = 0.6) thin films are of n-type nature.
... Based on the deposition pressures, a clear shift in the spectra can be observed. Generally, in polycrystalline semiconductors, both transmission and absorbance are affected by the stoichiometric deviation, quantum size effect and disorder at grain boundaries [45]. Absorbance spectra of four annealed metal-oxide films at three different deposition pressures is calculated using the following equation: ...
E-beam evaporated metal-oxide thin films have been studied with different stoichiometries as carrier transport materials for large-scale perovskite solar cell devices. The thin films are deposited through a reactive evaporation of pure metals in various oxygen atmosphere pressures. The measured optical and electrical properties were used in numerical modelling using SCAPS-1D software to demonstrate a power conversion efficiency in excess of 26%. X-ray photoelectron spectroscopy and optical characterization confirmed the variation of the oxygen concentration into these films with respect to the deposition pressures. The electrical measurements using hall probes complies with the reasonable data range. The field emission scanning electron microscopy demonstrated the deposition of dense, homogeneous and pin-hole-free uniform films throughout the substrate’s surface. Hydrophobic surface was found for the films grown with nano-porous structure. In particular, large-scale vapour deposition of perovskite solar cells becomes feasible due to such fabrication technique without breaking the vacuum.
... Despite the presence of nanopores, 100% relative density has been considered when measuring the electrical conductivity, as this represents the lower bound for electrical conductivity values. The electrical conductivity at room temperature was found to be 6 S m −1 , which is higher than reports for other chemically grown films via chemical deposition 41,42 and dip-coating 43 as well as previous reports for physically grown films using thermal evaporation, 44 which typically report an electrical conductivity only as large as 0.1 S m −1 . Hence, our values are 60 times higher due to the novel solution-processable and postprocessing techniques, in addition to having the potential to be compatible to on-chip technologies at the nanoscale. ...
Direct patterning of thermoelectric metal chalcogenides can be challenging and is normally constrained to certain geometries and sizes. Here we report the synthesis, characterization, and direct writing of sub-10 nm wide bismuth sulfide (Bi2S3) using a single source, spin coatable, and electron beam sensitive bismuth(III) ethylxanthate precursor. In order to increase the intrinsically low carrier concentration of pristine Bi2S3, we developed a self-doping methodology in which sulfur vacancies are manipulated by tuning the temperature during vacuum annealing, to produce an electron-rich thermoelectric material. We report a room temperature electrical conductivity of 6 S m-1 and a Seebeck coefficient of -21.41 µV K 1 for a directly patterned, sub-stoichiometric Bi2S3 thin film. We expect that our demonstration of directly-writable thermoelectric films, with further optimization of structure and morphology can be useful for on-chip applications.
... The direct band gap value of CdO thin films had also reported in the literature 2.38 eV [31]. Typically, in semiconductor materials, the energy band gap values can be impacted by the quantum size effect [50]. ...
Conducting cadmium oxide (CdO) thin film samples were deposited on amorphous glass substrates at the optimized substrate temperature (200 °C) as a function of carrier gas pressure (10.8, 12.7, 14.7, 16.7 and 18.6 × 10 ⁴ N m ⁻² respectively) by spray pyrolysis technique using nebulizer. XRD results showed that all the CdO thin films were polycrystalline in nature along with cubic structure. The scanning electron microscopy (SEM) images revealed that all the thin films had a sphere like grains without any cracks. The elemental composition of the film is analyzed with EDAX spectrum formed in stochiometric range. Direct energy gap values were found to be had decreased from 2.46 to 2.42 eV as the function of carrier gas pressure had increased from 10.8 to 14.7 × 10 ⁴ (N m ⁻² ) and the energy gap increased further. All the as deposited samples of Cd–O vibration bond (690 cm ⁻¹ ) were confirmed by FTIR spectrum. PL emission spectra revealed that all the CdO thin films exhibit a strong emission (green) peak at 520 nm. High carrier concentration (2.88 × 10 ¹⁹ cm ⁻³ ), low resistivity (4.76 × 10 ⁻³ Ω cm) and high figure of merit (25.0 × 10 ⁻³ ) were observed for 14.7 × 10 ⁴ (N m ⁻² ) carrier gas pressure of CdO thin film.
... These results indicate a tendency to a certain narrowing in the gap against the thickness occurs and the absorption edge is red shift in thicker films [33]. Generally, in polycrystalline semiconductor, the energy band gap can be affected by the quantum size effect [36], alteration in the preferred orientation of the film [37], disorder and dislocation density at the grain boundaries [38]. The sharp diminution of energy band at higher substrate temperature could be due to the constitution of decentralized states in the band gap region. ...
Using nebulized spray pyrolysis technique, we investigate tin oxide (SnO2) thin films had been coated with different substrate temperature (300–500 °C) onto microscopic glass substrate. All the prepared films have tetragonal crystalline structure with preferential orientation (110) observed by X-ray diffraction analysis. The reduced strain due to the increase of substrate temperature from 300 to 450 °C increased the average crystalline size from 27.40 to 42.99 nm and then decreased further. All the films display high transmittance in the visible and also in IR region. As the substrate temperature had increased from 300 to 500 °C, the average transmittance of SnO2 thin films varied between 79 and 90%. The energy band gap values had diminished from 3.91 to 3.75 eV by increasing the substrate temperature. The refractive index (n) of these films had increased from 2.11 to 2.32 with increase in substrate temperature from 300 to 450 °C and then decreased further. The optical static and high frequency dielectric constants (εo and ε∞) have been determined as a role of substrate temperature. The surface morphology of these thin films exhibited polyhedron-shaped grains obtained by scanning electron microscope. Energy dispersive X-ray analysis proved the presence of Sn and O elements in the as-prepared SnO2 films. Hall effect measurements shows that the film had deposited at 450 °C exhibited lowest resistivity 6.53 × 10⁻³ Ω cm and highest figure of merit 9.14 × 10− 3 (Ω/sq)⁻¹ among all the samples. Activation energy varied between 0.14 and 0.20 eV with the increase of substrate temperature from 300 to 500 °C.
... Since grain size impacts the energy level of electrons, the band gap will be dependent on the thickness of the nanostructured thin films [50]. The energy band gap can be affected by the crystalline size and crystal imperfections, which results in the orientation of the individual crystallites, quantum size effect, and disorder at the grain boundaries [51,52]. Bandgap [76][77][78][79][80][81][82][83][84][85][86][87] broadening with increasing thickness is mainly attributed to the reduction of band bending at grain boundaries [53]. ...
In this study, we report results on coating silicon solar cells with undoped and cobalt-doped zinc oxide (5%, 10%, 15%, and 20%) nanoparticles ranging in diameter from 46 nm to 87 nm, synthesized by a simple low-temperature precipitation method. The morphology and structure of nanoparticles have been characterized by transmission electron microscopy and X-ray diffraction spectroscopy. The average size of nanoparticles was found to increases with the increase in cobalt concentration. Doped and undoped zinc oxide thin films were deposited by a simple spin coating technique on silicon solar cells. Optical properties of the cobalt-doped zinc oxide layer have been investigated. We estimated the thin film stress by adding nanoparticles layers and found that the stress is lowest for the 139 nm cobalt-doped zinc oxide layer. Bandgap was found to increase with an increase in zinc oxide nanoparticle thin film thickness. Photoluminescence spectra show a blue shift in the near band edge emission peak with increase in thickness. Current-Voltage measurement confirms that there is an enhancement in power conversion efficiency as the thickness of zinc oxide nanoparticles varied from 58 nm to 139 nm. In general, the conversion efficiency shows an increasing trend up to 139 nm of thickness in silicon solar cells coated with doped and undoped zinc oxide nanoparticles. In addition, there is an enhancement of external quantum efficiency with an increase in thickness of zinc oxide layer. The optimal thickness of nanostructured zinc oxide film layer to enhance the efficiency of the silicon photovoltaic cell was experimentally determined to be 139 nm.
... There are several chemical and physical preparation methods for bismuth sulfide thin films including thermal evaporation [22], reactive evaporation [23], Hotwall method [24], chemical vapor deposition (CVD) [25], molecular layer epitaxy (MLE) [26], successive ionic layer adsorption and reaction (SILAR) [27], self-assembled monolayer method (SAMs) [28], spray pyrolysis (SP) [29], sol-gel [30], electrodeposition [31,32] and chemical bath deposition (CBD) [33][34][35]. ...
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.
... 26 In addition, owing to the large bandgap of Mo-and W-based compounds, TMDs only have applications in part of the visible range of the electromagnetic spectrum. 26 However, bismuth(III) sulfide (Bi 2 S 3 ), one of the TMD materials, exhibits a direct band gap energy (from 1.2 eV to 1.7 eV), [27][28][29][30] which can be tuned by its thickness and/or grain size, 31 making it applicable for ultraviolet, visible and near infrared photodetectors. Moreover, Bi 2 S 3 has a high absorption coefficient of ∼10 5 cm −1 (at a wavelength of approximately 600 nm) 32 and relatively high carrier mobility (μ e = 200 cm 2 V −1 s −1 ), 33 enabling broadband light absorption and efficient photogenerated carrier collection within a film of a few micrometers thick. ...
Two-dimensional (2D) bismuth (III) sulfide (Bi2S3) nanosheets as non-toxic graphene-like nanomaterials, was successfully fabricated by a facile liquid phase exfoliation (LPE) method. A robust photodetector employing Bi2S3 nanosheet film has been firstly fabricated via a facile fabrication process on ITO-coated glass. UV-Vis-NIR and Raman spectra were carried out and confirmed the inherent optical and physical properties of Bi2S3 nanosheets. Photoelectrochemical (PEC) measurements demonstrate that significantly higher photocurrent density (42 μA/cm2) and enhanced photoresponsivity (210 μA/W), at a lower bias potential in alkaline solution, of the Bi2S3 nanosheets-based photodetector are achieved, as compare with those of other 2D nanomaterials-based photodetectors under light irradiation. Furthermore, the as-prepared Bi2S3 nanosheets-based photodetector not only exhibits an appropriate capacity of self-driven broadband and high-performance photoresponse but also displays strong long-term stability of the ON/OFF switching behaviour without any external protection in alkaline solutions. Because of facile synthesis via a LPE method, higher photocurrent density and photoresponsivity, self-driven performance and long-term stability of the Bi2S3 nanosheets-based photodetector at lower bias potential in alkaline solution, the present work can provide fundamental acknowledgement of the high performance of this new kind of PEC-type 2D nanosheets-based photodetector.
... Various reports deal with the deposition of Bi 2 S 3 thin films using different methods such as chemical bath deposition [219][220][221], spray pyrolysis [222][223][224], solution-gas interface techniques [225] and electrode positioning [226,227] using different sulphide ion releasing source such as thiosulfate, thioacetamide and thiourea [228,229]. However, very few reports are available on the deposition of Bi 2 S 3 thin films via the successive ionic layer adsorption and reaction method (SILAR) [216,230,231]. ...
... Now days nanoscale materials are of particular interest due to their innovative structural, electrical, surface morphology and optical properties. They are useful in bioelectronics, biosensing, optoelectronic devices [1]. The synthesis of chalcogenide of groups II-VI semiconductors has been obtained in the form of nanocrystalline thin films. ...
Uniform and adhesive cadmium sulphide (CdS) thin films were prepared by using ultrasonic chemical bath deposition (UCBD) and chemical bath deposition (CBD) techniques. Cadmium sulphate and thiourea were used as inorganic precursors. The deposited CdS thin films are extensively studied for characterization using X-ray diffraction (XRD), UV-Visible–NIR absorption spectroscopy, photoluminescence spectroscopy (PL) and scanning electron microscopy (SEM). The structural analysis is subjected to the XRD spectra which confirmed the formation of nanocrystalline CdS thin films with hexagonal closed packed structure. Absorption spectra revealed that, CdS films deposited by UCBD have high optical band gap values as compared to those with CBD. Pl Spectra showed that, the band edge emission shifted towards blue region in case of UCBD which can be assigned as a formation of nanosonic thin films. Nanosonic is an emerging new field, which provides interlink and inter relation between ultrasound and nanomaterials. SEM analysis showed almost uniform grain on surface of the substrate.
... The direct optical band gaps of In 2 S 3 [36][37][38]. Typically, in polycrystalline semiconductors, the energy band gap can be impacted by the quantum size effect [39], modification in the preferred orientation of the film [40], disorder and dislocation of density at the grain boundaries [41]. The sharp reduction of energy band gap at higher precursor concentration could be owing to the constitution of localized states in the band gap region. ...
The present work investigates the effect of precursor concentration (mc) on the structural, optical, morphological and electrical conductivity properties of In2S3 thin films grown on amorphous glass substrates by nebulized spray pyrolysis (NSP) technique. The mixed phase of cubic and tetragonal structure of In2S3 thin films at higher concentration has been observed by X-ray diffraction pattern. The reduced strain by increasing the precursor concentration increased the average crystallite from 17.8 to 28.9nm. The energy dispersive analysis by X-ray (EDAX) studies confirmed the presence of In and S. The transmittance, optical direct band gap energy, Urbach energy and skin depth of In2S3 films have been analyzed by optical absorption spectra. The better conductivity and mobility noticed at mc=0.15M are explained by carrier concentration and crystallite. Better optical and electrical conductivity behaviour of In2S3 thin film sample proposes for effective solar cell fabrication.
... Nanostructures of Bi2S3 have potential applications in electrochemical hydrogen storage, hydrogen sensors, X-ray computed tomography imaging, biomolecule detection and photoresponsive materials [8]. Much research have been carried out on the preparation, characterization and applications of Bi2S3 thin films by employing several deposition techniques such as chemical deposition [9][10][11][12][13][14][15][16], vacuum evaporation [17][18][19][20] , cathodic elec- trodeposition [21], anodic electrodeposition [22], hot-wall method [23], solution gas interface [24], spray deposition [7,[25][26][27][28] , ultrasonic methods [29,30], microwave irradiation [31,32], * E-mail address: hussainmakak@gmail.com. http://dx.doi.org/10.1016/j.ejbas.2016.06.003 2314-808X/© 2016 Mansoura University. ...
Ni-doped nanocrystalline Bi2S3 thin film is deposited on boron doped single crystal (p)-Si substrate by chemical bath deposition to form (p)Si/(n)Bi2S3 heterojunction structure. The electrical characterization of the (p)Si/(n)Bi2S3 heterojunction is carried out in the temperature range of 300 K–340 K and capacitance–voltage characteristics is measured at a frequency of 1 KHz at 300 K. Various junction parameters are calculated from the I–V characteristics. The ideality factor is found to be greater than unity with high series resistance. The ideality factor and series resistance decreases, whereas the saturation current density increases with increase in temperature. The J–V characteristics under illumination showed poor photovoltaic effect of the junction. The existence of higher value of ideality factor and large number of interface states in (p)Si/(n) Bi2S3 heterojunction reduced the photovoltaic conversion efficiency.
... There is general agreement that deposition at low (~ room) temperature leads to the growth of mixed phases, while the rhombohedral phase dominates at high growth temperature 17 ; a pure orthorhombic phase has been rarely reported [18][19] . As a consequence, little and confusing information on the electrical, optical and structural properties of this material is available, in net contrast to Bi2S3, Sb2S3 and Sb2Se3 that are relatively well characterized [20][21][22][23] . Theoretical results using ab initio methods suggest that orthorhombic Bi2Se3 should have a bandgap of approximately 0.9 eV [24][25] , too small to enable efficient solar cells, but no experimental report was found to support this claim. ...
A metastable phase of Bi2Se3 with orthorhombic structure has been obtained by potentiostatic electrodeposition onto Si(100) substrate. The ideal stoichiometry and single orthorhombic phase could be obtained only within a restricted potential window, where mutual underpotential codeposition is assumed to occur. Optical and electrical characterization indicates a bandgap of 1.25 eV, close to the maximum efficiency in the Shockley-Queisser limit, and n-type semiconducting behavior with moderate electrical resistivity. Theoretical calculations using density functional theory were used to support the structural and optical results. Due to the favorable set of properties with respect to isomorphic compounds such as Bi2S3, Sb2S3 and Sb2Se3 this material could lead to efficient and low-cost new thin film-based photovoltaic devices.
... [4][5][6] Particularly, Bi 2 S 3 is interesting because it has no toxic elements in its structure 7 showing n-type conductivity, and a band gap ranging from 1.3 eV to 2.3 eV, 7-10 which are essential requirements for photovoltaic applications, especially the usage for Cu 3 BiS 3 -based solar cells. 11 Additionally, in the last decade the interest in the Bi 2 S 3 compound has grown, being used in photovoltaic applications [12][13][14] and in the manufacturing of optoelectronic, thermoelectronic, photocatalytical, and photoelectrochemical devices. 15,16 On the other hand, different techniques for the synthesis of Bi 2 S 3 , where these elements are found 17,18 : spray pyrolysis, PVD, electrochemical deposition, CBD, and SILAR, has been reported. ...
This work presents the results of synthesis and characterization of polycrystalline n-type Bi2S3 thin films. The films were grown through a chemical reaction from co-evaporation of their precursor elements in a soda-lime glass substrate. The effect of the experimental conditions on the optical, morphological structural properties, the growth rate, and the electrical conductivity (σ) was studied through spectral transmittance, X-ray diffraction (XRD), atomic force microscopy (AFM) and σ versus T measurements, respectively. The results showed that the films grow only in the orthorhombic Bi2S3 bismuthinite phase. It was also found that the Bi2S3 films present an energy band gap (Eg) of about 1.38 eV. In addition to these results, the electrical conductivity of the Bi2S3 films was affected by both the transport of free carriers in extended states of the conduction band and for variable range hopping transport mechanisms, each one predominating in a different temperature range.
... Recently, nanostructured thin films have opened a new era of interest in many technological applications in the field of electronics. The ability to tune the structural, morphological and optical properties by size and surface manipulation offers us to design and develop nanostructured thin films through the solution chemistry [1]. The syntheses of II-VI semiconductor metal chalcogenide are quiet fascinating till date. ...
Cadmium sulfide (CdS) thin film consisting of nanowires over a flat CdS thin film were synthesized by depositing cadmium hydroxide [Cd (OH) 2 ] nanowires (NW) bundles, followed by conversion to sulfide phase by using ion exchange route at room temperature (300 K) based on negative free energy of formation. The influence of post annealing treatment on as-deposited CdS NW films has been studied in the temperature range 423–523 K through the observation of nanowires alignments. The annealing effect on the intrinsic properties have been studied in relation with the crystallites sizes, micro strain, dislocation density and optical band gap of the deposited films. Furthermore, the behavior of inter-and intramolecular hydroxide ion (OH À) has been investigated from FTIR analysis. Additionally, the effects of post annealing on photovoltaic device performance has been scrutinized and the obtained results were correlated with structural and optical properties.
... For example, optoelectronic devices, particularly solar energy conversion devices, could be modied accordingly. 6 Group V-VI semiconductors with energy gaps covering the visible spectral range are promising candidates for PEC solar cells. 7,8 Bi 2 S 3 and Bi 2 Se 3 are two very important wide gap semiconductors because of their applications in optoelectronics and PEC solar cells. ...
Nanostructured bismuth sulphoselenide (Bi2(S1−xSex)3) thin films have been synthesized using a simple, cost-effective chemical bath deposition (CBD) method at room temperature (300 K). Structural, compositional, morphological and optical characterization and photoelectrochemical performance testing of these Bi2(S1−xSex)3 thin films has been carried out. The X-ray diffraction (XRD) study demonstrates that these thin films are nanocrystalline in nature with pure orthorhombic crystal structures. X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS) show that the deposited thin films are nearly stoichiometric in nature. Field emission scanning electron microscopy (FESEM) reveals different morphologies for the Bi2(S1−xSex)3 thin films. The linear nature of the plots seen in the UV-Vis-NIR absorption study confirms the direct allowed type of transition. J–V measurements with a solar simulator were carried out for all samples and the highest photoconversion efficiency, 0.3845%, has been recorded for the Bi2Se3 thin film. The significant boost in photoelectrochemical (PEC) performance might be due to the larger surface area with lower dislocation density and microstrain with a lower level of grain boundary resistance of Bi2Se3 thin films.
... The energy bandgap of the polycrystalline semiconductor is known to be affected by the stoichiometric deviations, the variation of grain sizes [22], changes in preferred orientation of the films [23], dislocation density, and disorder at the grain boundaries [24]. No remarkable stoichiometric deviations or changes in preferred orientation have been observed in the XRD patterns or EDS spectra, so the surfaces of the films were further researched. ...
Pulsed laser deposition (PLD) with different levels of laser power was first used to deposit In2S3 films from homemade, high-purity In2S3 targets. This process was followed by post-annealing in an N2 atmosphere to improve the films' crystallinity and conductivity. The annealed films were verified to be stoichiometric, body-centered, tetragonal In2S3 with the preferred orientation (103). The bandgap of the films decreased from 2.8 to 2.2 eV with an increase in the laser power, which was believed to be the result of the grain growth caused by the higher laser power. The electrical transport property of the bottom-gate field-effect transistor revealed the n-type conduction of the annealed In2S3 films, and the heterojunction p+-Si/annealed In2S3 film showed remarkable photovoltaic behavior upon light illumination, indicating that PLD-deposited In2S3 films may have great potential as a buffer layer in thin-film solar cells. What's more, doped In2S3 films can be easily realized due to the fairly stoichiometric transfer of the PLD method.
This work presents a holistic approach to the fabrication of bismuth sulfide (Bi2S3) photodetectors, with a particular emphasis on material structure and morphology. Bi2S3 particles were synthesized using a microwave-assisted method, employing bismuth nitrate and L-cysteine as the sulfur source. Polyvinylpyrrolidone with two different molecular weights was used as a viscosity modifier to control the size and morphology of the particles. The as-synthesized powders were drop-casted onto interdigitated gold electrodes from an ethanol suspension and evaluated using different light sources. The results demonstrate that submicrometric material with a slightly higher aspect ratio generated a higher photocurrent under the same conditions, attributed to enhanced carrier transport due to the reduced rod diameter, photogating effects, and Schottky emission. Bi2S3 lamellar microrods exhibited responsivity of 0.93, 0.21, and 0.40 mA/W for red (628 nm), green (517 nm), and blue (468 nm) light, respectively. This resulted in detectivity in the range of 1.17 to 5.32 × 10¹⁰ Jones for the visible light spectrum.
The Cu/Sn/S stack was obtained at room temperature by the thermal evaporation technique at vacuum ~ 2 x 10 − 4 Pa using sequentially evaporated layer deposition (SELD) technique on corning 2947 substrate. The as-deposited stack was regrown to provide Cu 3 SnS 4 (CTS) phase on annealing at temperatures varying from 623 to 723 K for one hour in vacuum level ~ 2 x 10 − 1 Pa. The as-deposited stack exhibits amorphous behaviour, whereas films grown at annealing temperature (T A ) from 623–723 K attain nanostructured Cu 3 SnS 4 phases. The influences of annealing temperature on the characteristics of these films were investigated by analyzing their structural, morphological, compositional, optical, and electrical behaviour using analytical characterization techniques. The annealed films of CTS crystallize in a tetragonal crystal system and provide a space group of 42m [121]. The grown films provide granular-type structures, and the particles grown at 673 K show an increased size. The bandgap (E g ) of films decreases from 2.13 to 1.78 eV, and their absorption coefficient (α) > 10 ⁵ cm − 1 . The low resistivity of 9.37 x10 − 3 Ω-cm, high mobility of 56.4 cm ² /V-s, and acceptor concentration of 1.19 x10 ¹⁹ cm ³ at 673 K result from an increased crystallite size, which reduces grain boundary scattering. Cu 3 SnS 4 is a promising absorber layer for thin-film solar cells, known for its tunable bandgap, high optical absorption, low cost, and use of earth-abundant elements.
Quasi-1D chalcogenides have shown great promises in the development of emerging photovoltaic technologies. However, most quasi-1D semiconductors other than Sb2Se3 and Sb2S3 have been seldom investigated for energy generation applications. Indeed, cationic or anionic alloying strategies allow changing the bandgap of these materials, opening the door to the development of an extended range of chalcogenides with tuneable optical and electrical properties. In this work, Bi incorporation into the Sb2Se3 structure has been proved as an effective approach to modulate the bandgap between <1.0 eV and 1.3 eV, demonstrating conversion efficiencies between 3 and 5% for 0.01 < x ≤ 0.10. However, there is a noticeable deterioration in optoelectronic parameters for x > 0.1. In order to better understand the underlying mechanisms leading to the formation of (Sb1-xBix)2Se3, and thus design specific strategies to enhance its properties, thin films with different annealing time and temperature have been synthesized and characterized. Interestingly, it has been observed that Sb2Se3 and Bi2Se3 are formed first, with Bi melting at 300 °C and diffusing rapidly towards the surface of the film. At higher temperature, the binary compounds combine to form the solid solution, however as the dwell time increases, (Sb1-xBix)2Se3 decomposes again into Bi2Se3 and Sb. This study has shown that the material is essentially limited by compositional disorder and recombination via defects. Likewise, routes have been proposed to improve morphology and uniformity of the layer, achieving efficiencies higher than 1% for x > 0.2.
In2S3 thin films were grown on indium tin oxide-coated glass substrates by a chemical spray pyrolysis technique at different substrate temperatures (300 °C, 360 °C, 400 °C and 460 °C). Structural analysis of the deposited films shows a combination of tetragonal and cubic structures. The crystallite size of the films increases with the substrate temperature. Elemental analysis reveals that the films deposited at substrate temperature of 360 °C are sulfur deficient. Surface topography of the In2S3 thin films was examined by atomic force microscopy (AFM), scanning electron microscopy (SEM) and optical profilometry. The results clearly show that the films adhere well to the substrate with good homogeneity. The surface roughness is also showed to increase with the substrate temperature. The optical properties of In2S3 thin films were studied as a function of wavelength. The transmittance spectra show that the film deposited at 300 °C acquires relatively high transmittance in the visible region. The optical band gap is found to be direct, and it decreases with the increase in substrate temperature. Photoluminescence (PL) study reveals blue and green emissions.
Nanostructured Tin oxide and Indium (In) doped SnO 2 were prepared by low cost and easy to manufacture method, which is a spray pyrolysis technique (SPT). Film transmittance was noticed to decrease from 67% to 56% (at 800 nm) on doping. XRD patterns revealed that tin oxide and 1% or 3% In:SnO 2 thin films are polycrystalline and preferred orientation is 113. AFM micrographs prove that the spherical shape grains are uniformly distributed with average grain size of about 88 nm and root-mean-square (rms) roughness was about 3.5 nm. It can be concluded that the deposited samples are good candidates for use in solar cells applications. Keywords: spray pyrolysis technique (SPT), (SnO 2 : In), X-ray diffraction (XRD), transmittance, atomic force microscopy (AFM) 摘要 纳米氧化锡和铟（In）掺杂的 SnO2 是通过低成本，易于制造的方法制备的，这是一种喷雾热解 技术（SPT）。 在掺杂时，发现膜的透射率从 56％降低到 67％（在 800 纳米处）。 X 射线衍射 图表明，氧化锡和 1％或 3％的 In：SnO2 薄膜是多晶的，优选取向为 113。AFM 显微照片证明球 形晶粒均匀分布，平均晶粒尺寸约为 88 纳米，均方根 （均方根）粗糙度约为 3.5 纳米。 可以得 出结论，沉积的样品是用于太阳能电池应用的良好候选者。。 关键词: 喷雾热解技术，（SnO2：In），X 射线衍射，透射率，原子力显微镜
The ferroelectric photovoltaic (FPV) effect obtained in inorganic perovskite ferroelectric materials has received much attention because of its large potential in preparing FPV devices with superior stability, high open-circuit voltage (Voc) and large short-circuit current density (Jsc). In order to obtain suitable thickness for the ferroelectric thin film as light absorption layer, in which, the sunlight can be fully absorbed and the photo-generated electrons and holes are recombined as few as possible, we prepare Pb0.93La0.07(Zr0.6Ti0.4)0.9825O3 (PLZT) ferroelectric thin films with different layer numbers by the sol-gel method and based on these thin films, obtain FPV devices with FTO/PLZT/Au structure. By measuring photovoltaic properties, it is found that the device with 4 layer-PLZT thin film (~300 nm thickness) exhibits the largest Voc and Jsc and the photovoltaic effect obviously depends on the value and direction of the poling electric field. When the device is applied a negative poling electric field, both the Voc and Jsc are significantly higher than those of the device applied the positive poling electric field, due to the depolarization field resulting from the remnant polarization in the same direction with the built-in electric field induced by the Schottky barrier, and the higher the negative poling electric field, the larger the Voc and Jsc. At a -333 kV/cm poling electric field, the FPV device exhibits the most superior photovoltaic properties with a Voc of as high as 0.73 V and Jsc of as large as 2.11 μA/cm². This work opens a new way for developing ferroelectric photovoltaic devices with good properties.
Tris(O-ethylxanthato) bismuth(III) [Bi(S2COEt)3], tris(O-ethylxanthato) antimony(III) [Sb(S2COEt)3] and tris(O-ethylxanthato) indium(III) [In(S2COEt)3], have been synthesized and employed for the preparation of Bi-In-S and Sb-In-S systems by solventless thermolysis. M2-2xIn2xS3 (where M = Bi or Sb) alloys were obtained using a mixture of In(S2COEt)3 and M(S2COEt)3 molecular precursors, with different mole fraction of indium x (0 ≤ x ≤ 1) at 300 °C. The structural, compositional, optical and morphological properties of the synthesized M2-2xIn2xS3 samples have been characterized using a range of techniques including powder X-ray diffraction (p-XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy, Raman spectroscopy and UV–Vis absorption spectroscopy. PXRD data suggests the incorporation of molar ratio of indium up to x ≤ 0.4 into the M2S3 does not alter the orthorhombic crystal structure of M2S3. Higher quantities of indium (x ≥ 0.6) changes the crystal structure to cubic M2S3. The estimated elemental compositions from EDX data are in line with the stoichiometric ratio expected. SEM images revealed that the morphology of M2-2xIn2xS3 (0 ≤ x ≤ 1) samples varied significantly with the changes in indium mole fraction in the precursor mixture. Elemental mapping of the mixed samples M2-2xIn2xS3 (0 ≤ x ≤ 1) revealed uniform elemental distributions of M, In and S in every sample investigated. The estimated band gap of Bi2-2xIn2xS3 films varied from 1.66 to 2.39 eV, while the band gap of Sb2-2xIn2xS3 films varied in the range 2.19 – 2.9 eV, and the energy can be tuned by variation of the indium content.
The present work focuses on the effect of substrate temperature and molar concentration on properties of polycrystalline Zn0.80Cd0.20O thin films deposited on glass substrates by chemical spray pyrolysis. X-ray diffraction (XRD) results have revealed the presence of mixed faces of cubic-hexagonal structure in the polycrystalline film and substrate temperature was optimized for 723 K to get good crystallinity of the deposited films. Crystallite size, dislocation density, micro strain and number of crystallites in the deposits were calculated by using XRD data. Scanning electron microscopy images showed the spherical grain surface morphology, which can be modified by the variation in the substrate temperature and molarity. It was noted that the optical transmittance and energy band gap increased as temperature increased and was found to decrease with molarity. The analysed optical measurements have been used to calculate the values of refractive index and extinction coefficients in the wavelength range of 400–600 nm. The n-type electrical conductivity was enhanced with increasing deposition temperature and molarity due to the increase in crystallinity and free carrier concentration respectively.
In2S3 thin films with different S/In molar ratios (from 1.5 to 3.5) were deposited via a spray pyrolysis technique on glass substrates at 340°C. Then, the obtained films were annealed at the same temperature 400°C for 2 h. X-ray diffraction study reveals the formation of cubic -In2S3 phase with (400) as preferred orientation. The crystallite size varies in the range 64-97 nm. Optical analysis exhibits that transmittance in visible and near infrared regions is higher than 65% for all films. The optical band gap varied from 2.58 to 2.67 eV. The optical parameters (refractive index, extinction coefficient, dielectric constants) were calculated through the transmittance (T) and reflectance (R). Dispersion parameters (E0, Ed), high frequency dielectric constant ( ), refractive index ( ), oscillator length strength (S0), average oscillator wavelength (λ0) and optical moments (M-1, M-3) were determined by Wemple DiDomenico model. The surface and volume energy losses with photon energy were also calculated. The optical and electrical conductivities were estimated. These properties of In2S3 films are important for photovoltaic application.
Zinc-doped In2S3 thin films have been deposited by spray pyrolysis method at 350°C on glass substrates with ITO contacts. The samples were sealed under vacuum (10-3 Torr) into a pyrex tube and then annealed for two hours at temperatures ranging from 300°C to 450°C with a step of 50°C. The effect of the annealing temperature (Ta) on structural, morphological and optical properties of the In2S3 films was studied. The films, annealed at Ta ≤ 300°C, result in films that consist of tetragonal β-In2S3 phase with (220) preferential orientation, while for films annealed at Ta > 300°C, a structural transition from tetragonal to cubic β-In2S3 occurs with (400) preferential orientation. The film grain size decreases from 42 to 33 nm. The surface morphology analysis reveals that the films annealed at 300°C present an average roughness of 40 nm. The optical band gap is found to be direct and it decreases with the increase of annealing temperature. A higher optical transmittance of 80 % is obtained at Ta = 350°C.
In this material production research, undoped and Ba-doped nanostructured PbS films are fabricated on glass surfaces by SILAR method. The structural, optical and morphological properties of the films are examined via scanning electron microscopy, UV-vis spectrophotometry and X-ray diffraction analysis. Scanning electron microscopy analysis revealed that Ba-doping concentration influences the size of the thin film's nanoparticles. Xray diffraction results showed that all of the thin films are in a face centered cubic structure. Optical studies, in the room temperature, revealed that the optical band gap of the films increases as Ba-doping concentration is increased. The intercept values on the energy axis in the range of 1.86 eV and 2.12 eV for 1% and 8% Ba-doped PbS films respectively. As a result, it is concluded that the structural, optical and morphological properties of the fabricated thin films are directly depend on the Ba doping ratio.
In recent years, Zn 1-xCo xO has attracted special attention due to the highest solubility of Co in ZnO matrix and is expected to behave as a dilute magnetic semiconductor, which exhibits ferromagnetic properties. Thin films of cobalt doped ZnO were deposited on glass substrates by chemical spray pyrolysis at various deposition temperatures, T s that vary in the range, 260 - 350° C. 0.1M aqueous solutions of zinc acetate (Zn (CH 3COO) 2.2H 2O) and cobalt acetate (Co (CH 3COO) 2.4H 2O) were taken as precursors. The as-grown layers were characterized by different techniques to know their physical properties. The X-ray diffraction studies revealed that all the layers exhibited wurtzite structure with (002) plane as the preferred orientation. The grain size of the films was varied in the range, 20 - 40 nm. The average optical transmittance of the films was found to be > 75% in the visible region and the evaluated optical band gap of the films decreased from 3.37 eV to 3.22 eV with the increase of substrate temperature. The details of these results were reported and discussed.
This paper examines the influence of constituent materials properties on the optical and photoelectrical characteristics of the heterojunctions. The edge of intrinsic absorption band of GaSe and InSe crystals, at the temperature of 78 K, consists of direct exciton bands from the states n=1 and n=2. Effective mass electron-hole pair in InSe is equal to 0.14 m0. Effective mass of electrons in p-GaSe is equal to 0.18 m0. Oxide-GaSe and oxide-GaSe heterojunctions were manufactured by thermal oxidation of In, Sn, Ti, Bi, Zn, Cu and Cd metallic films. The heterojunctions of GaSe and InSe semiconductors with studied oxides of metals reveal high photosensitivity in the visible and near IR spectrum. Photosensitivity band edge to low energies is determined by the GaSe or InSe band gap and the edge to high energy edge-by the respective oxides' gap. Free path of minority charge carriers in GaSe layer at the TiO 2/GaSe:Cu, In2O3/InSe and TiO2//InSe heterojunction's interface depends on the fabrication technology and ranges between 0.56 μm÷1.97μm. The same parameter for structures based on InSe lies between 1,00÷3,45 μm for structures based on p-GaSe.
In the paper we report some theoretical results on the thickness and temperature dependences of the electrical conductivity and band gap width for semiconducting thin films. The expressions for electrical conductivity and energy gap are deduced as functions of the scattering parameter of film surfaces, potential in surface layer, mean free path of charge carriers, thickness of the surface layer, film thickness, temperature, and some characteristic parameters of the bulk material.
This paper is a review of our work on nanocrystalline semiconductor films which exhibit pronounced size quantization effects in three dimensions, manifested by large blue‐shifts in their optical absorption spectra. The films are prepared by either chemical solution deposition (CdSe and PbSe) or by electrodeposition from nonaqueous electrolytes (CdSe and CdS). Except for PbSe, where the nanocrystals are surrounded by a matrix, the films are comprised of aggregated nanocrystals. Crystal size (typically from 6 nm), and therefore absorption spectra, can be controlled by deposition temperature, illumination during deposition (for chemically deposited films), solution composition, and post annealing. The crystal size dependence of chemically‐deposited films on experimental parameters (temperature, illumination, reactant concentrations) is discussed. CdSe nanocrystals were epitaxially electrodeposited on single‐crystal Au. The nanocrystal distribution (isolated or aggregated) could be controlled by deposition current and temperature. All these films exhibit photoelectrochemical behavior but no corresponding solid state photovoltaic behavior. A model is proposed based on electron/hole separation by kinetic differences in charge injection into an electrolyte rather than by a built‐in space charge layer in the semiconductor. The films can behave as both ‘n’ ‐ or ‘p’‐type, with respect to direction of photocurrent flow, by changes in the semiconductor surface properties and/or the electrolyte, in agreement with this model.
Bi2S3 thin films have been deposited from an aqueous acidic bath using thioacetamide CH3-CS-NH2 (TAM) as a sulfide ion source. The preparative parameters are optimized and growth mechanism is discussed. X-ray diffractograms indicate that the films are polycrystalline in nature. A microstructural study has been carried out using a scanning electron microscopy technique. From optical absorption studies the energy bandgap of Bi2S3 is estimated to be 1.84 eV. Room temperature resistivity is of the order of 105 ohm cm.
Very small ZnS and CdS crystallites are made and stabilized in aqueous and methanolic media without organic surfactants. Low temperature (−77 °C) synthesis in methanol produces the smallest crystallites, ≈30 Å diameter cubic CdS and <20 Å diameter cubic ZnS. The crystallites are characterized by transmission electron microscopy and in situ optical spectroscopy (λ≳200 nm). The crystallites are too small to exhibit bulk band gaps in their optical spectra. In the band gap region, the small crystallites show a higher energy absorption threshold with a resolved spectral feature (quantum size exciton peak), not present in the spectra of larger crystals. The far ultraviolet spectra are unaffected by size at present resolution. These results can be understood in terms of the crystallite molecular orbitals, and an elementary confined electron and hole model.
Stoichiometric and cohesive CdS films were obtained by a solution growth technique. The crystalline structure of the CdS film on glass substrate was wurtzite highly oriented, in (002) direction as revealed by X-ray and selected area electron diffractometries. Composition of the CdS films was examined in detail by electron probe micro-analysis and X-ray energy dispersion spectroscopy. Quantum size effects were confirmed from the blueshift in the optical band gap of the CdS film.
Metal chalcogenide thin film preparation by chemical deposition is currently attracting considerable attention as it is relatively inexpensive, simple and convenient for large area deposition. A variety of substrates such as insulators, semiconductors or metals can be used since it is a low temperature process which avoids oxidation or corrosion of metallic substrates. It is a slow process which facilitates better orientation of crystallites with improved grain structure. Depending upon the deposition conditions, film growth can take place by ion-by-ion condensation of the materials on the substrates or by adsorption of the colloidal particles from the solution onto a substrate. Using this method thin films of groups II–VI, IV–VI, V–VI, I–III–VI etc. have been deposited.In this review article, the theoretical background of chemical deposition is described in detail. A survey of binary and ternary metal chalcogenide thin films is given with respect to their preparative parameters, structural, optical and electrical properties. Such films have been used in solar selective coatings, solar control photoconductors, solid state and photoelectrochemical solar cells.
We report here results from experiments on low-frequency Raman scattering from CdS microcrystals of various sizes embedded in a germanium dioxide glass matrix. We observed peaks in the low-frequency region in the tail parts of the Rayleigh lines and we found that the frequencies of these peaks were proportional to the inverse microcrystal diameters and that the size dependences of the peak shifts agreed fairly well with the calculated results based on Lamb’s theory. Furthermore, we found that these Raman-scattering spectra had the characteristic polarization properties. Our results show that the observed low-frequency Raman scattering originates from confined acoustic vibrations of a spherical CdS microcrystal.
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