Akhilesh Tripathi

Structural, optical and photoluminescence study of nanocrystalline SnO2 thin films deposited by spray pyrolysis

Undoped SnO2 thin films prepared by spray pyrolysis method reveal polycrystalline nature with prominent peaks along (110), (101) and (211) planes. All the films are nanocrystalline with particle size lying in the range of 3·14–8·6 nm calculated by DS formula. Orientation along plane (200) decreases continuously as molar concentration of SnO2 increases. Dislocation density along plane (110) also decreases as molar concentration increases except 0·4 M SnO2 thin film. Scanning electron microscopy image of the films contain jelly structures along with agglomerated clusters of particles. SnO2 synthesized successfully, which confirms by Fourier transform infra-red spectroscopy. The optical transmittance spectra of 0·2 M SnO2 thin film shows transmittance about 50–60% transmission in visible and near infrared region with a sharp cut off in the ultraviolet region. The transmission decreases in visible and near infrared region as molar concentration increases. Broad UV emission at 398 nm is observed in photoluminescence spectra of the films along with a blue emission, when excited at 250 nm wavelength. Emission intensity randomly changed as SnO2 molar concentration increases. When excited at 320 nm, one UV and two visible peaks appeared at 385, 460 and 485 nm, respectively.

Synthesis and optical studies of chemically synthesized PPy/Al2O3 nanocomposites

In the present work, we have synthesised pure and 2wt% Al2O3 doped PPy by the chemical oxidation method. XRD patterns of 2wt% Al2O3 doped PPy shows several broad peaks while pure PPy shows only one single peak indicating poor crystalline phase of PPy. FTIR spectra confirm the formation of PPy and also suggest that doping of Al2O3 in PPy does not affect its structure. PL shows several emission peaks for both samples located at ∼365 nm with two shoulders at ∼473 nm and ∼533 nm. The further synthesis and properties study is under investigation.

Morphological and photoluminescence study of chemically synthesized Al2O3 polythiophene composite

Undoped and Al2O3 doped Polythiophene were synthesized by chemical route method. All the samples were characterized by fourier transform infra-red spectroscopy. Scanning electron microscopy shows the formation of spherical like particles for Al2O3 polythiophene composite and its size decreases continuously as Al2O3 doping percentage increases. Photoluminescence spectra were recorded at excitation wavelength 325 nm. All the samples have mainly two visible peaks at 462 and 490 nm respectively. The PL of present sample may have several optoelectronic applications like organic light emitting diodes (OLEDs), and photovoltaic cell etc.

Structural and optical properties of Sn1-xMnxO2 thin films

Sn1-xMnxO2 thin films are deposited by spray pyrolysis method. XRD of all the thin films show the amorphous nature. Synthesis of SnO2 is also confirmed by FTIR spectroscopy. Undoped SnO2 thin film is 60-70 % transparent in visible and near IR region and it increases up to 80-90% for 20 at. % Mn doped SnO2 thin film. The optical band gap is tunable linearly between 3.34 to 3.96 eV for 0≤x≤0.20 for Sn1-xMnxO2 amorphous thin films.

Investigation of photoresponse in cadmium sulfide nanoparticles

In this work, we report on the photo-response of CdS nanoparticles prepared by simple solid state reaction method. The X-ray diffraction (XRD) study has confirmed the formation of cubical zinc blende (c) phase. In the photo-response study, voltage dependence of photocurrent and darkcurrent as well as temporal rise and decay of photocurrent of CdS nanoparticles have been investigated. The photo-response of prepared sample has been measured under visible illumination using thick film of powder with out any binder. The photocurrent (Ipc) and darkcurrent (Idc) follow power law with applied voltage i.e. I α Vr. The rise and decay of photocurrent show negative photoconductivity.

Humidity response of SnO2thin films deposited by spray pyrolysis

Transparent SnO 2 films, using precursor solutions of different molar concentrations (0.2, 0.4, 0.6 and 0.8M), are prepared by spray pyrolysis method. XRD spectra of the films reveal polycrystalline nature. Surface morphology presents jelly like structures as seen through scanning electron microscope. Humidity sensing behaviour has been studied considering resistance of the films as a monitor parameter. Sensitivity is seen to increase as relative humidity (RH) increases for all the samples. Sensitivity is highest for SnO 2 film prepared with precursor of lowest molar concentration (0.2M). Response and recovery time, for the sample with highest sensitivity, are found to be 20 and 25 sec respectively.

Humidity response of SnO[sub 2] thin films deposited by spray pyrolysis

Transparent SnO 2 films, using precursor solutions of different molar concentrations (0.2, 0.4, 0.6 and 0.8M), are prepared by spray pyrolysis method. XRD spectra of the films reveal polycrystalline nature. Surface morphology presents jelly like structures as seen through scanning electron microscope. Humidity sensing behaviour has been studied considering resistance of the films as a monitor parameter. Sensitivity is seen to increase as relative humidity (RH) increases for all the samples. Sensitivity is highest for SnO 2 film prepared with precursor of lowest molar concentration (0.2M). Response and recovery time, for the sample with highest sensitivity, are found to be 20 and 25 sec respectively.

Humidity response of SnO2 thin films deposited by spray pyrolysis

Transparent SnO 2 films, using precursor solutions of different molar concentrations (0.2, 0.4, 0.6 and 0.8M), are prepared by spray pyrolysis method. XRD spectra of the films reveal polycrystalline nature. Surface morphology presents jelly like structures as seen through scanning electron microscope. Humidity sensing behaviour has been studied considering resistance of the films as a monitor parameter. Sensitivity is seen to increase as relative humidity (RH) increases for all the samples. Sensitivity is highest for SnO 2 film prepared with precursor of lowest molar concentration (0.2M). Response and recovery time, for the sample with highest sensitivity, are found to be 20 and 25 sec respectively.