J. V. Thombare

The effects of electron irradiation on the optical properties of the organic semiconductor polypyrrole

The optical properties of polypyrrole (Ppy) thin films upon 2 MeV electron beam irradiation changes with different doses. The induced changes in the optical properties for Ppy thin films were studied in the visible range 300 to 800 nm at room temperature. The optical band gap of the pristine Ppy was found to be 2.19 eV and it decreases up to 1.97 eV for a 50 kGy dose of 2 MeV electron beam. The refractive index dispersion of the samples obeys the single oscillator model. The obtained results suggest that electron beam irradiation changes the optical parameters of Ppy thin films.

Synthesis, characterization and surface wettability study of polypyrrole films: Effect of applied constant current density

Polypyrrole thin films were prepared by galvanostatic mode of electrodeposition. The applied constant current density changes structural, optical and surface wettability properties of polypyrrole thin films. The prepared films were characterized for structural, optical and surface wettability study. Fourier transform infrared spectroscopy shows the benzoid and qunoid like structures in polypyrrole films. The UV-Visible absorption study shows that the optical density varies with the applied deposition current density. The band gap energy calculated from the Tauc’s plot was found to be 2.25 eV and shows the film is in semiconductor nature. The surface wettability study confirms hydrophilic nature of polypyrrole films.

Optical properties of electrochemically synthesized polypyrrole thin films： the electrolyte effect

Polypyrrole thin films are prepared by the potentiostatic mode of electrodeposition at +0:7 V versus a saturated calomel electrode (SCE). The polypyrrole films are prepared in the presence of different electrolytes such as: p-toluene sulphonic acid (PTS), oxalic acid and H2SO4. The prepared films are characterized by UV—vis absorption spectroscopy and normal reflectance measurements. The electrochemically synthesized films are semiconductor in nature. The band gap energy of polypyrrole thin films is found to be 1.95, 1.92 and 1.79 eV for H2SO4, oxalic acid and p-toluene sulphonic acid, respectively. The normal reflectance spectroscopy of polypyrrole films shows that the maximum reflectance is in the presence of p-toluene sulphonic acid; this is may be due to a more distinct microstructure than the others. The optical constants such as the extinction coefficient, refractive index, optical conductivity, etc. are calculated and studied with various electrolytes.

The influence of monomer concentration on the optical properties of electrochemically synthesized polypyrrole thin films

Polypyrrole (PPy) thin films were deposited on stainless steel and ITO coated glass substrate at a constant deposition potential of 0.8 V versus saturated calomel electrode (SCE) by using the electrochemical polymerization method. The PPy thin films were deposited at room temperature at various monomer concentrations ranging from 0.1 M to 0.3 M pyrrole. The structural and optical properties of the polypyrrole thin films were investigated using an X-ray diffractometer (XRD), FTIR spectroscopy, scanning electron microscopy (SEM), and ultraviolet—visible (UV—vis) spectroscopy. The XRD results show that polypyrrole thin films have a semi crystalline structure. Higher monomer concentration results in a slight increase of crystallinity. The polypyrrole thin films deposited at higher monomer concentration exhibit high visible absorbance. The refractive indexes of the polypyrrole thin films are found to be in the range of 1 to 1.3 and vary with monomer concentration as well as wavelength. The extinction coefficient decreases slightly with monomer concentration. The electrochemically synthesized polypyrrole thin film shows optical band gap energy of 2.14 eV.

Synthesis of polyaniline nanofibres by SILAR method for supercapacitor application

Polyaniline nanofibres were synthesized using a economical and environment friendly SILAR method. As deposited polyaniline thin films were characterized for their structural, morphological and electrochemical properties. FT- IR study confirms the polymerization of aniline onto glass substrates. Amorphous, hydrophilic polyaniline thin films show semiconducting behaviour with optical band gap of 2.07 eV. Cyclic voltammetry have been used to explain the supercapacitive properties of deposited polyaniline thin film electrode in aqueous 1M H2SO4 electrolyte The value of specific capacitance was found to be 590 F/g in the potential window of -0.6 to 1.0 V vis-a-vis SCE in 0.1 M H2SO4 as an electrolyte with the scan rate 5 mV/sec. Scan rate study reveals the high power pulse response of polyaniline electrode showing highest capacitance of 590 F/g decreasing with increase in scan rate. EIS study supports the capacitive properties of polyaniline electrodes.

Studies on electrochemically synthesized polypyrrole (Ppy) thin films for supercapacitor application

In the present study, we prepared polypyrrole thin films by electrochemical polymerization method. The deposited films were characterized by different physical and chemical methods. Structural study was made by FTIR spectroscopy, the surface morphological study was made with the help of Scanning electron microscopy (SEM), the optical study and band gap energy was studied with the help of UV-Vis absorption spectroscopy. Supercapacitor testing was made with the help of cyclic voltammetry in the 0.5 M H2SO4 electrolyte. The SEM picture revealed the formation of well-adherent and cauliflower structure. Electrochemically synthesized Polypyrrole thin film showed the band gap energy value of 1.8 eV. The value of specific capacitance was found to be 540 F/g in the potential window of -0.2 to 0.8 V vis-a-vis SCE in 0.1 M H2SO4 as an electrolyte with the scan rate 25 mV/sec.

Photoelectrochemical cell performance of electrodeposited iron doped zinc selenide thin film

In the present investigation, we are discussing the results on photoelectrochemical cell performance of iron doped zinc selenide thin films by Electrodeposition. Thin films were deposited by Galvanostatically as well as potentiostatically at an aqueous solution onto stainless steel substrate as well as ITO (indium tin oxide). Precursor of zinc selenide is zinc sulphate (ZnSO4), selenium dioxide (SeO2) and ferrous sulphate (FeSO4). The deposited films were characterized by different physico-chemical characterization such as, for structural study X-ray diffraction study was used, Scanning electron microscopy (SEM) for surface morphology, optical absorption study made by UV spectrometer and it showed that the semiconductor nature of the electrodeposited zinc selenide thin films with band gap 2.6 eV and PEC performance shows that Isc is 360 mA and Voc is 135 mV.

Chemical oxidative polymerization and characterization of polypyrrole thin films for supercapacitor application

In present study, we prepared polypyrrole thin films by chemical oxidation polymerization method. The polypyrrole thin films were prepared with three different oxidants namely, ammonium per sulfate (APS), K₂S₂O₈ and Fe(NO₃)₃. The deposited films were characterized by UV-Vis absorption spectroscopy, UV-Vis normal reflectance measurements, Scanning electron microscopy (SEM) and Cyclic Voltammetry. The chemically synthesized films showed the conducting form of polypyrrole. The supercapacitor study was made with the help of cyclic voltammetry. The polypyrrole electrode displays good electrochemical capacitance within the electrochemical window between -0.2 and 0.8 V (vs. SCE). The maximum value of specific capacitance 113 F/g was obtained for the films deposited using K₂S₂O₈ at the scan rate of 25 mV/sec vs SCE in 0.1 M H₂SO₄ as an electrolyte.

Galvanostatically deposited Cd 0.7 Fe 0.3 Se electrode for solar cell application

Thin films of Cd0.7Fe0.3Se have been prepared on stainless steel and fluorine doped tin oxide (FTO) coated glass substrates using electrodeposition technique. Double distilled water containing precursors of Cd, Fe and Se are used with ethylene diamine tetra-acetic acid (EDTA) disodium salt as a complexing agent to obtain good quality deposits by controlling the rate of reactions. The different preparative parameters like concentration of bath, deposition time, pH of the bath and Fe content in the bath have been optimized by photoelectrochemical (PEC) technique in order to get good quality thin films. Different techniques have been used to characterize electrodeposited Cd0.7Fe0.3Se thin films. The X-ray diffraction (XRD) analysis reveals that the films Cd0.7Fe0.3Se are polycrystalline in nature with crystallite size of 282 Å for the films deposited with optimized preparative parameters. Scanning electron microscopy (SEM) study reveals that all grains uniformly distributed over the surface of stainless steel substrate indicates well defined growth of polycrystalline Cd0.7Fe0.3Se material. Optical absorption shows the direct band gap energy of 1.84 eV. Photoelectrochemical (PEC) solar cell study shows the films of Cd0.7Fe0.3Se are more photosensitive.

Effect of electron beam irradiation on electrodeposited nanostructured copper selenide thin films

Copper selenide nanorods fused at both ends with various diameters and lengths were obtained by irradiating electrodeposited thin films. The irradiation dose can be used to control the diameter of the electrodeposited nanorods to within the range of 70-100 nm. This paper reports the effect of high-energy (7 MeV) electron beam irradiation on the optical properties of CuSe thin films grown by conventional electrodeposition method on steel substrates. Upon irradiation the band gap energy increased from a value of 2.82 eV to 3.03 eV where as there is a drastic change in their morphology. The grain size increases with electron beam irradiation and material become poor crystalline. Similar results were observed in the X-ray diffraction studies, where peak intensity decreases with electron beam irradiation.