Suvarta D. Kharade

Room temperature deposition of nanostructured Bi2Se3 thin films for photoelectrochemical application: effect of chelating agents

Nanostructured bismuth selenide (Bi2Se3) thin films have been deposited by chemical bath deposition method at room temperature using three different chelating agents, trisodium citrate, triethanolamine and ethylenedimminetetraacetic acid. The structural, morphological, optical and photoelectrochemical properties of Bi2Se3 thin films have been investigated as a function of different chelating agents. X-Ray diffraction studies revealed that the films were nanocrystalline in nature with a rhombohedral crystal structure. Trisodium citrate chelate resulted in Bi2Se3 thin films with poor crystallinity; further improvement in the crystallinity of the films was observed with triethanolamine and ethylenedimminetetraacetic acid chelates. From scanning electron microscopy, a uniform sphere-like morphology having an average sphere diameter of 90 nm was observed with trisodium citrate chelate. In the case of triethanolamine, a fibrous morphology with an average fiber thickness of 60 nm was observed, whereas for ethylenedimminetetraacetic acid chelate, a vertically arrayed petal-like morphology having petal thickness of 50–70 nm was observed. The UV-Vis absorption studies revealed that the band gap energy of the Bi2Se3 thin films with trisodium citrate, triethanolamine and ethylenedimminetetraacetic acid chelates was 1.55, 1.48 and 1.40 eV, respectively. The maximum short circuit current densities (Jsc) of 0.158, 0.214 and 0.284 mA cm−2 and the corresponding open circuit voltages (Voc) of 196, 206 and 217 mV were obtained with trisodium citrate, triethanolamine and ethylenedimminetetraacetic acid chelates, respectively. The Bi2Se3 thin films deposited using triethanolamine and ethylenedimminetetraacetic acid chelates show better photoelectrochemical performance as compared with trisodium citrate chelate.

Microwave assisted synthesis, characterization and thermoelectric properties of nanocrystalline copper antimony selenide thin films

In the present work, we have synthesized p-type copper antimony selenide (Cu3SbSe4) thin films in an aqueous alkaline medium using a microwave assisted synthesis technique. The deposited thin films were characterized by UV-Vis-NIR spectroscopy, X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM) and thermoelectric techniques. On the basis of experimental results, a possible reaction mechanism has been discussed in detail. The band gap of the as deposited film is 1.94 eV and after annealing it reaches 1.87 eV for Cu3SbSe4. XRD results indicate that the as deposited thin films of CuSbSe2 have an orthorhombic crystal structure with secondary mixed phases and after annealing this is converted to Cu3SbSe4 having a pure tetragonal crystal structure. FESEM micrographs of Cu3SbSe4 showed a spherically diffused granular morphology having an average grain size of 25 nm. The HRTEM result of Cu3SbSe4 shows good crystallinity with a lattice spacing of 0.327 nm along the (112) plane. The EDS spectrum shows the presence of Cu, Sb and Se elements. The thermoelectric figure of merit (ZT) of the as deposited film is calculated to be 0.059 at 300 K and that of annealed Cu3SbSe4 is found to be 0.141 at 300 K.

A facile and low cost strategy to synthesize Cd1−xZnxSe thin films for photoelectrochemical performance: effect of zinc content

In the present work, we report a facile chemical route for the deposition of Cd1−xZnxSe thin films using a simple, self-organized arrested precipitation technique (APT). The effect of Zn content on optical, structural, morphological, compositional and photoelectrochemical properties in Cd1−xZnxSe thin films was investigated. The optical properties and band gap profile of Cd1−xZnxSe thin films were varied with respect to Zn content. The estimated direct optical band gap was found to be in the range of 1.77 to 1.98 eV. X-ray diffraction (XRD) studies revealed that the films were nanocrystalline in nature with a pure cubic crystal structure and the calculated crystallite size lies in the range 36.5 to 66.3 nm. Scanning electron microscopy (SEM) demonstrates that the surface morphology can be improved with incorporation of Zn into the CdSe lattice. Compositional analysis of all samples was carried out using energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), which confirms the stoichiometric deposition of Cd1−xZnxSe thin films. J–V characteristics of all samples were studied in sulphide/polysulphide redox electrolyte. A high efficiency of 0.68% was observed due to lower crystallite size and higher surface area. These results show that by varying Zn content in Cd1−xZnxSe thin films, the photoelectrochemical performance can be enhanced.

Photocurrent enhancement in a Cu2Cd(SSe)2 photoanode synthesized via an arrested precipitation route

In the present investigation, nanostructured combinatorial quaternary Cu2Cd(SSe)2 thin films have been successfully synthesized via a self organized arrested precipitation technique (APT). The synthesized quaternary Cu2Cd(SSe)2 thin films show an enhancement in the photocurrent for Cu-poor composition, which signifies that the synthesized quaternary material is commensurate with other Cu-based quaternary and multinary materials for solar cell application. The optostructural study clearly illustrates that the synthesized thin films have optimized band gap energy with mixed crystal structures. The morphological study indicates the formation of hierarchical microstructures. A compositional study confirms the formation of quaternary thin films with the required composition. J–V curves demonstrate that photocurrent enhancement is observed in quaternary Cu2Cd(SSe)2 thin films with an increase in Cu-content. The resultant maximum short circuit current density (Jsc) and open circuit voltage (Voc) are 1.23 mA cm−2 and 437 mV respectively.

Enhanced photoelectrochemical performance of novel p-type MoBiCuSe4 thin films deposited by a simple surfactant-mediated solution route

Low-dimensional nanostructures with reduced grain boundaries show superior charge transportation in a photoelectrochemical cell. Therefore, nanostructures of MoBiCuSe4 thin films deposited using different surfactants are expected to be favorable for providing a direct pathway for smooth transport of photogenerated charge carriers across a reduced number of grain boundaries within the photoelectrode. In the present investigation, we have studied the effect of different surfactants, such as polyethylene glycol (PEG), sodium dodecylsulfate (SDS) and trioctylphosphine oxide (TOPO), on the opto-structural, morphological and photoelectrochemical (PEC) properties of MoBiCuSe4 thin films. We have demonstrated a soft chemical route that facilitates the formation of a compact, homogeneous deposition with a large effective (photoactive) surface area, which could be suitable for PEC cells. The MoBiCuSe4 thin films have been deposited using the arrested precipitation technique (APT) and their formation confirmed by energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The nanocrystalline nature of the MoBiCuSe4 thin films and the mixed rhombohedral crystal structure with reduced number of grain boundaries were confirmed by the X-ray diffraction (XRD) pattern. The direct allowed type of transition in the material, with an average absorption coefficient above 104 cm−1, makes it suitable for PEC applications. The maximum light conversion efficiency achieved for MoBiCuSe4 thin films deposited with surfactant is 0.18%. PEC analysis verifies that the synthesized nanostructures of the surfactant-assisted MoBiCuSe4 photoelectrode material are suitable for PEC cells.

Surfactant mediated synthesis of bismuth selenide thin films for photoelectrochemical solar cell applications

In the present report, nanostructured bismuth selenide (Bi2Se3) thin films have been successfully deposited by using arrested precipitation technique (APT) at room temperature. The effect of three different surfactants on the optostructural, morphological, compositional and photoelectrochemical properties of Bi2Se3 thin films were investigated. Optical absorption data indicates direct and allowed transition with a band gap energy varied from 1.4 eV to 1.8 eV. The X-ray diffraction pattern (XRD) revealed that Bi2Se3 thin films are crystalline in nature and confirmed rhombohedral crystal structure. SEM micrographs shows morphological transition from interconnected mesh to nanospheres like and finally granular morphology. Surface topography of Bi2Se3 thin films was determined by AFM. Compositional analysis of all samples was carried out by energy dispersive X-ray spectroscopy (EDS). Finally, all Bi2Se3 thin films shows good PEC performance with highest photoconversion efficiency 1.47%. In order to study the stability of Bi2Se3 thin films four cycles are repeated after gap of one week each. Further PEC performance of all Bi2Se3 thin films are also supported by electrochemical impedance (EIS) measurement study.

Single step fabrication of CuS thin film via hydrothermal route for solar cell application

In the present investigation, we have successfully synthesized Copper Sulfide (CuS) thin film via facile and low cost hydrothermal method. The synthesized (CuS) thin film was characterized for optical, morphological and compositional analysis. Surface profiler study shows thickness of thin film is 420 nm. The optical study revealed that the direct allowed type of transition having band gap 1.95 eV. The X-Ray diffraction (XRD) study illustrated that CuS thin film was nanocrystalline in nature with pure cubic crystal structure and calculated crystalline size is 18 nm. Well adherent and crack free deposition on substrate was observed in Scanning Electron Microscopy (SEM) analysis. SEM images show that synthesized CuS thin film having nanoflakes like morphology. The Energy Dispersive Spectra (EDS) pattern confirmed that Cu and S elements are present in deposited thin film. At last, we have critically analyzed photoresponse property to check the suitability of deposited materials for photoelectrochemical (PEC) application. PEC study illustrates that, the synthesized CuS thin film having power conversion efficiency 0.162 %.In the present investigation, we have successfully synthesized Copper Sulfide (CuS) thin film via facile and low cost hydrothermal method. The synthesized (CuS) thin film was characterized for optical, morphological and compositional analysis. Surface profiler study shows thickness of thin film is 420 nm. The optical study revealed that the direct allowed type of transition having band gap 1.95 eV. The X-Ray diffraction (XRD) study illustrated that CuS thin film was nanocrystalline in nature with pure cubic crystal structure and calculated crystalline size is 18 nm. Well adherent and crack free deposition on substrate was observed in Scanning Electron Microscopy (SEM) analysis. SEM images show that synthesized CuS thin film having nanoflakes like morphology. The Energy Dispersive Spectra (EDS) pattern confirmed that Cu and S elements are present in deposited thin film. At last, we have critically analyzed photoresponse property to check the suitability of deposited materials for photoelectrochemical (PEC)...