Amrik Singh; Devendra Mohan; Dharmavir S. Ahlawat; Sandeep Chopra
Abstract
Indium Tin Oxide (ITO) coated glass acts as a substrate for photoanode of Dye Sensitized Solar Cells (DSSCs). The ITO substrate was irradiated by oxygen ion with different fluence (1x10 11 and 1x10 12 ions/cm 2 ) at 100 MeV energy. The TiO2 films were also subjected with same ion irradiation at 100 MeV ...
Read More
Indium Tin Oxide (ITO) coated glass acts as a substrate for photoanode of Dye Sensitized Solar Cells (DSSCs). The ITO substrate was irradiated by oxygen ion with different fluence (1x10 11 and 1x10 12 ions/cm 2 ) at 100 MeV energy. The TiO2 films were also subjected with same ion irradiation at 100 MeV of energy with fluence of 1x10 11 ions/cm 2 and 5x10 12 ions/cm 2 . At 100 MeV energy of O 7+ ion the electronic and nuclear energy loss for TiO2 film have been measured 7.38x10 -1 KeV/nm and 3.8x10 -4 KeV/nm respectively. However, the electronic and nuclear energy loss of ion irradiation for ITO substrate were 7.4x10 -1 KeV/nm and 4.06x10 -4 KeV/nm respectively. Similarly longitudinal/ lateral straggling of ITO and TiO2 have been found 3.87 μm/2.50 µm and 3.62 µm/1.14 μm respectively. Further, the structural and optical properties of these samples were monitored by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-visible spectroscopy. It was found that oxygen ion (O 7+ ) irradiation of ITO film has slightly changed the crystallinity and transmission decreases. Furthermore, the particle size of TiO2 thin film has been obtained 80 nm corresponding to (101) plane of XRD pattern. In the case of ITO thin film the crystallite size and band gap changes from 62.35 nm to 53.89 nm and 3.993 eV to 3.971 eV at 1x10 12 ions/cm 2 respectively. Moreover this paper is also reporting that irradiation by swift heavy ion has changed the transmission of the ITO films, and its values decreases as compared to pristine (ITO) which degraded the performance of DSSC. Consequently, a very small value of absorbance is reported for ITO film. However, the absorbance of TiO2 film has found to increase with irradiation of oxygen ion at fluence of 1x10 12 ions/cm 2 and decreased at 5x10 12 ions/cm 2 . It is also confirmed that the absorbance of TiO2 film and TiO2/ITO photoanode increases with irradiation of oxygen ion at fluence of 1x10 12 ions/cm 2 and decreased at 5x10 12 ions/cm 2 . The band gap values of TiO2 thin film were obtained to have a change from 3.37 eV (for pristine) to 3.44 eV at 5x10 12 ions/cm 2 . But the decrease in band gap is also found 3.17 eV at fluence of 1x10 12 ions/cm 2 . However, N719 dye loaded O 7+ (1x10 12 ions/cm 2 ) irradiated TiO2 film show high absorption as compared to other samples. Thus the dose of O 7+ irradiation at fluence 1x10 12 ions/cm 2 may fabricate more efficient DSSC and consequently future prospective of such type of photoanode materials for dye sensitized solar cells seems to be bright.
Ranjana S. Varma; D.C. Kothari; S. Santra; R.G. Thomas; R. Tewari; S. Neogy; C.S. Suchand Sandeep; Reji Philip; D. Kanjilal
Abstract
In the present work, we have used swift heavy ions (SHI) irradiation and post irradiation annealing to synthesize Ag nanoparticles in fused silica. Fused silica samples deposited with 15 nm of Ag film were irradiated using SHI beam of 120 MeV Ag 9+ ions at different fluences and post irradiation annealing ...
Read More
In the present work, we have used swift heavy ions (SHI) irradiation and post irradiation annealing to synthesize Ag nanoparticles in fused silica. Fused silica samples deposited with 15 nm of Ag film were irradiated using SHI beam of 120 MeV Ag 9+ ions at different fluences and post irradiation annealing was done at 500 °C in air for 30 min. The samples were characterized using UV-vis absorption spectroscopy, Rutherford Backscattering Spectrometry (RBS), GAXRD, Transmission Electron Microscopy (TEM), and open aperture z-scan measurements. The signature of Ag nanoparticles was observed in optical absorption spectra and the average size of the Ag nanoparticles was estimated using Mie’s theory. The size of the nanoparticles (~3 nm) was also confirmed from the GAXRD and TEM measurements. RBS results for Ag/SiO2 irradiated with the fluence of 5 x10 13 ions/cm 2 shows the decrease in slope at the interface of the Ag profile, indicating a partial mixing at a fluence of 5 x10 13 ions/cm 2 . Open aperture z-scan measurement of Ag/SiO2 SHI irradiated sample after annealing shows a saturation behavior, indicating that the sample is optically non-linear. The sample shows saturation behavior but does not show optical limiting behavior, which indicates that the size and number density of nanoparticles are low. The ability to control the particle size using ion beam technique as a function of fluence and observed nonlinearity results provide concrete evidence that Ag nano composite glasses can be used in nonlinear and optical limiting application.
R.S. Chauhan; Vijay Kumar; Anshul Jain; Deepti Pratap; D.C. Agarwal; R.J. Chaudhary; Ambuj Tripathi
Abstract
Nanocrystalline tin oxide (SnO2) thin films were fabricated using pulsed laser deposition (PLD) technique. The as-deposited films were irradiated at liquid nitrogen (LN2) temperature using 100 MeV Ag ions at different fluences ranging from 3×10 13 to 3×1014 ions/cm 2 and at 75o with respect ...
Read More
Nanocrystalline tin oxide (SnO2) thin films were fabricated using pulsed laser deposition (PLD) technique. The as-deposited films were irradiated at liquid nitrogen (LN2) temperature using 100 MeV Ag ions at different fluences ranging from 3×10 13 to 3×1014 ions/cm 2 and at 75o with respect to surface normal. Pristine and irradiated samples were characterized using XRD, AFM, Raman and I-V (current-voltage characteristics) for the study of modifications in structural, surface morphological, bond angle and resistivity respectively. XRD patterns show that the pristine film is highly polycrystalline and irradiation amorphizes the film systematically with increasing the irradiation fluence. The surface of the pristine film contains nanograins of tin oxide with roughness 5.2 nm. Upon irradiation at lower fluences agglomeration is seen and roughness increased to 10.8 nm. Highest fluence irradiation again develops nanograins with roughness 7.5 nm. Raman spectra and I-V characteristics also confirms the irradiation induced amorphization. The observed results are explained in the frame work of thermal spike model.
Vijay Kumara; Anshul Jaina; Deepti Pratapa; D.C. Agarwalb; I. Sulaniab; V. V. Siva Kumarb; A. Tripathib; S. Varmac; R.S. Chauhan
Abstract
Nano crystalline tin oxide thin films were deposited on Si and quartz substrates using R. F. magnetron sputtering technique. A set of films was annealed in oxygen environment. These as-deposited and annealed films were irradiated using 100 MeV Ag ions at different fluences ranging from 3×10 11 ...
Read More
Nano crystalline tin oxide thin films were deposited on Si and quartz substrates using R. F. magnetron sputtering technique. A set of films was annealed in oxygen environment. These as-deposited and annealed films were irradiated using 100 MeV Ag ions at different fluences ranging from 3×10 11 to 3×10 13 ions/cm 2 . The structural, optical and surface morphological properties of films were studied using X-ray diffraction (XRD), UV-Vis spectroscopy, and atomic force microscopy (AFM) techniques. As deposited films showed the polycrystalline nature and annealing enhances the crystallinity along a particular plane. Upon irradiation at lower fluences up to 3×1012 ions/cm 2 , reduction in crystallinity is observed but at highest fluence 1×10 13 ions/cm 2 a small increase in crystallinity occurs as inferred from XRD spectra. UV-Vis study showed red shift at the lower fluences and blue shift at higher fluences. The pristine film, as observed in AFM micrograph, has randomly distributed surface nano structures with broader size distribution. Irradiation induces the formation of regular shape structures with narrow size distribution. These results may be attributed to the energy deposited by swift heavy ions in the film.
A. Kumar;Somik Banerjee
Abstract
Structural and conformational modifications in conducting polymer nanostructures viz., Polyaniline (PAni) nanofibers induced by swift heavy ion (SHI) irradiation have been investigated employing TEM, XRD, UV-Vis, FTIR and micro-Raman spectroscopy. Upon interaction with the highly energetic ions, PAni ...
Read More
Structural and conformational modifications in conducting polymer nanostructures viz., Polyaniline (PAni) nanofibers induced by swift heavy ion (SHI) irradiation have been investigated employing TEM, XRD, UV-Vis, FTIR and micro-Raman spectroscopy. Upon interaction with the highly energetic ions, PAni nanofibers are fragmented and get amorphized. The local range of order is found to decrease with a corresponding increase in the concentration of point defects and dislocations leading to the enhancement in strain. Vibrational spectra of the pristine and SHI irradiated PAni nanofibers studied using FTIR and micro-Raman (μR) spectroscopy indicate conformational changes in PAni nanofibers upon SHI irradiation. Loss of π-stacking due to the enhancement in the torsion angle between Cring-N-Cring upon irradiation is indicative of strong electrostatic interaction between the electron rich C-N site in the aromatic rings of PAni chains and the ion beam. The most significant variation in PAni nanofibers upon SHI irradiation is the transformation of para di-substituted benzene (benzenoid) structure of PAni into the quinone di-imine (quinoid) structures; a phenomenon that has been simultaneously observed in both the FTIR and Raman spectra. The presence of two main peaks representing the same structures in PAni nanofibers in both the Raman and IR spectra is because of the presence of delocalized sp2 phases and local disorder in PAni nanofibers, which gives rise to electrical and mechanical fluctuations that destroy the symmetry rules.
