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Swift Heavy Ion (SHI) beam irradiation has been used as an experimental technique to modify the material properties through the interaction of the ion beam with the target material. In this work, the properties of the pristine and 200 MeV Ag15+ ion beam irradiated lithium (3 wt%) doped WO3 (tungsten trioxide) thin films are reported. These thin films were spray deposited onto ITO coated glass substrates at 400 °C with thickness around 55 nm and irradiated with the 200 MeV Ag15+ ion beam at a fluence of 5 × 1012 ions/cm2. The XRD pattern of pristine film confirmed textured growth along the (211) plane with tetragonal phase, while the irradiated film was partially amorphous. Raman modes at higher wavenumbers 708 cm−1 and 806 cm−1 belong to W–O stretching modes, whereas modes at lower wavenumbers 133 cm−1 belong to lattice mode and 265 cm−1 are associated with W–O bending modes for pristine film. Upon irradiation, all the Raman modes vanished due to irradiation induced amorphization. The optical transparency of the film upon irradiation decreased significantly, and band gaps showed a red shift. The atomic force microscopy (AFM) images of pristine film surfaces were homogeneous, smooth and free from holes with small grains, whereas ion irradiated films exhibited isolated flattened particles of varying size on the surface. Room temperature transport properties were also measured using Hall effect for both the pristine and irradiated films. [ABSTRACT FROM AUTHOR]

Highlights • For 5 × 1012 fluence recrystallization by thermal spike occurs and XRD peaks reappeared. • Suppression of Raman modes observed for 5 × 1012 fluence due to irradiation induced defects. • Red shift was observed in both the direct and indirect band gaps of irradiated films. • WO 3 film showed distinct surface morphologies for different ion fluences. Abstract The physical properties of thin films can be modified by swift heavy ion (SHI) beam irradiation of the target material. Spray-deposited tungsten trioxide (WO 3) thin films of thickness 89 nm were irradiated with 200 MeV Ag15+ ion beam at various fluences of 5 × 1011, 1 × 1012, 5 × 1012 , and 1 × 1013 ions/cm2. The X-ray diffraction pattern of the pristine film was orthorhombic, while the irradiated film became amorphous at different fluences except for 5 × 1012 ions/cm2; this may be due to the re-crystallization effect induced by irradiation. The observed Raman modes for the pristine film were in good agreement with those reported for the irradiated WO 3 films. The intensity of Raman peaks decreased upto 5 × 1012 ions/cm2 and vanished completely at further higher fluences. The optical transparency of the pristine film was much higher than that of irradiated ones. Both the direct and indirect band gaps showed a red shift. AFM data revealed significant surface modifications after irradiation. Transport properties were also studied for both the pristine and irradiated films by the Hall effect. A decrease in resistivity was observed with the increase in fluence. These results are discussed in this paper. [ABSTRACT FROM AUTHOR]

Lithium (Li) (0–5 wt%) doped V 2 O 5 thin films were spray deposited at 450 °C onto ITO substrates. Structural analysis using X-ray diffraction and Raman spectroscopy revealed orthorhombic phase of the films. In addition to the V 2 O 5 phase, presence of VO 2 peaks due to high deposition temperature is also evident from structural and optical characterization. The non-stoichiometric nature of the films due to loss of the terminal O atom was confirmed from Raman spectroscopy. The direct band gap, indirect bandgap, and phonon energies were also calculated from optical studies. Different charge states of vanadium ions present in the film were identified from X-ray photoelectron spectroscopy study. Results from cyclic voltammetry experiments reflected significant differences between the undoped and Li doped V 2 O 5 samples. Transport properties by Hall-effect measured at room temperature indicated significant increase in conductivity, carrier concentration and mobility of V 2 O 5 thin films on doping with Li. A Dye Sensitized Solar Cell (DSSC) was fabricated using mobility enhanced 5 wt% Li doped V 2 O 5 film as photoanode and its efficiency was found to be 2.7%. A simple electrochromic cell is fabricated using undoped V 2 O 5 thin film to demonstrate the colour change. [ABSTRACT FROM AUTHOR]

Highlights: [•] Undoped film was oriented along the 〈0 k 0〉 direction. [•] Mo 3d 5/2 and 3d 3/2 doublet caused by spin–orbit coupling are resolved with a splitting of 3.1eV. [•] Direct and indirect band gaps showed red shift with ‘Li’ doping compared to undoped film. [•] Intensity of the green photoluminescence emission spectra is quenched with ‘Li’ concentration. [•] Dye sensitized solar cell is fabricated using undoped MoO3 thin film as photoanode. [ABSTRACT FROM AUTHOR]