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.

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.

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