Nanocrystalline cadmium sulfoselenide thin films have been synthesized using a self-organized arrested precipitation technique with different deposition times using triethanolamine as a complexing agent. Optical, structural, morphological and photoelectrochemical solar cell properties were investigated as a function of deposition time. A UV-Vis-NIR absorption study suggested a direct allowed transition type and the band gap energy decreased from 2.01 to 1.86 eV with the increase in deposition time. X-ray diffraction studies revealed that the thin films are nanocrystalline by nature with a pure hexagonal crystal structure and a calculated crystallite size of 51-68 nm. Field emission scanning electron microscopy demonstrated that the surface morphology was altered from nanoflakes to assorted nanoflakes-nanospheres and finally to a nanocoral-like morphology. X-ray photoelectron spectroscopy and energy dispersive X-ray spectroscopy showed that the composition of the Cd(SSe) thin films was of good stoichiometry. Electrical conductivity and thermoelectric power measurements confirmed that the deposited films were n-type semiconductors. From J-V measurements, a highest photo-conversion efficiency of 0.57% was achieved.The significant boost in the PEC performance might be due to the improved crystallinity along with lower values of the grain boundary resistance, dislocation density and the microstrain of the Cd(SSe) thin films.

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Herein, we report honeycomb nanostructured single crystalline hexagonal WO(3) (h-WO(3)) thin films in order to improve electrochromic performance. In the present investigation, honeycomb nanostructured WO(3) with different unit size and nanowire array with highly nanocrystalline frameworks have been synthesized via a hydrothermal technique. The influence of hydrothermal reaction time on the honeycomb unit cells, crystallite size, lithium ion diffusion coefficient and switching time for coloration/bleaching were studied systematically. The electrochromic study reveals that the honeycomb unit cell size has a significant impact on the electrochromic performance. Small unit cells in the honeycomb lead to large optical modulation and fast switching response. A large optical modulation in the visible spectral region (60.74% at λ = 630 nm) at a potential of -1.2 V with fast switching time (4.29 s for coloration and 3.38 s for bleaching) and high coloration efficiency (87.23 cm(2) C(-1)) is observed in the honeycomb WO(3) thin films with a unit cell diameter of 1.7 μm. The variation in color on reduction of WO(3) with applied potential has been plotted on an xy-chromaticity diagram and the color space coordinate shows the transition from a colorless to deep blue state.

In the present investigation, sea urchin like morphology of h-MoO 3 nanorods are successfully synthesized by chemical bath deposition (CBD) technique. The thermal stability, structural details, morphology and compositional analysis of MoO 3 was done using thermogravimetry (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED) and X-ray photoelectron spectroscopy (XPS) techniques respectively. The thermal analysis reveals presence of sharp exothermic peak at 409ºC indicating irreversible phase transition. X-ray diffraction pattern showed hexagonal to orthorhombic phase transition after annealing at 450ºC. As synthesized h-MoO 3 shows well oriented hexagonal rods with sea urchin like architecture while that of annealed MoO 3 sample revealed 2D layer by layer growth. The SAED pattern confirms single crystalline nature of as synthesized h-MoO 3 and polycrystalline nature of annealed α-MoO 3 . While XPS study of both confirms Mo +6 and O 2-oxidation states of elements. Furthermore, characteristic antibacterial properties of h-MoO 3 and α-MoO 3 against gram positive Bacillus megaterium, Streptococcus aureus and gram negative Escherichia coli is noted.

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In the present work, we have synthesized p-type copper antimony selenide (Cu 3 SbSe 4 ) 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 Cu 3 SbSe 4 . XRD results indicate that the as deposited thin films of CuSbSe 2 have an orthorhombic crystal structure with secondary mixed phases and after annealing this is converted to Cu 3 SbSe 4 having a pure tetragonal crystal structure. FESEM micrographs of Cu 3 SbSe 4 showed a spherically diffused granular morphology having an average grain size of 25 nm. The HRTEM result of Cu 3 SbSe 4 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 Cu 3 SbSe 4 is found to be 0.141 at 300 K.

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Hybrid APT method, novel custard apple-like cadmium sulfoselenide thin films, nanocrystalline pure phase, highest power conversion efficiency of 1.02%.