Sutripto Majumder

First report on a FeS-based 2 V operating flexible solid-state symmetric supercapacitor device

A high specific energy and specific power can be attained for the supercapacitor devices with the aid of optimum potential. The use of a flexible approach employing a solid-state device structure is always beneficial for advanced technological applications. Hence, effort has been made towards the fabrication of a complete solid-state symmetric and flexible supercapacitor device based on environmentally friendly and abundant iron sulfide as an electrode material, which has been obtained using a successive ionic layer adsorption and reaction method operated at room temperature (27 °C). An operating voltage of 2 V was achieved for the flexible device with a bending stability of 100% over a bending angle of 175° along with the LED glow working model. These outcomes can give new vision towards the construction of solid-state and flexible devices using a simple and low-cost method with potential ability towards roll-to-roll technology for commercialization.

Solution-processed CdS quantum dots on TiO2: light-induced electrochemical properties

Mesoporous titanium dioxide (TiO2) nanostructured thin films, formed by a simple chemical route, namely, the successive ionic layer adsorption reaction (SILAR) technique, were efficiently used to grow a cadmium sulphide (CdS) nanoparticle architecture for device grade applications. CdS nanoparticle have a highly symmetric size and shape that could be varied in a controlled manner (<10 nm size) depending on the number of SILAR immersions without the use of an organic linker molecule. XRD and HR-TEM studies showed the formation of CdS nanoparticles on TiO2 nanoparticles. Such a nanomorphology showed good optical coverage over the visible region of light, and it revealed a red-shift with respect to the number of CdS layers, which was confirmed by both optical and external quantum efficiency studies. The photoelectrochemical performance of the TiO2/CdS photoanodes showed that as the particle size of CdS increases with the number of SILAR immersions, the photocurrent density and photovoltage were found to be directly concurrent with the charge transport mechanism, which increases the cell efficiency.

Facile fabrication of CdS/CdSe core–shell nanowire heterostructure for solar cell applications

Hierarchical one-dimensional CdS nanowires (NWs)/CdSe core–shell heterostructure have been synthesized through a simple wet chemical approach. The formation of CdS NWs/CdSe core–shell has been confirmed by structural, morphological and optical analysis. Fascinatingly, an optimum number of CdSe nanoparticles loaded over CdS NWs boosts the device efficiency five times than a bare CdS NW structure. The effect of increasing the CdSe SILAR cycles over CdS induces red shift in the absorption wavelength along with quenching, which leads to the negative shift of the conduction band, and hence, increases the electron lifetime, as analyzed by photoluminescence, external quantum efficiency and Mott–Schottky studies. Interestingly, a discrepancy has been found in the device performance with an increase in the SILAR cycles beyond the optimum condition. The reason behind this fact has been investigated through different comprehensive photoelectrochemical characterization and discussed herein.

SILAR controlled CdSe nanoparticles sensitized ZnO nanorods photoanode for solar cell application: Electrolyte effect

Controlled growth of different sizes of cadmium selenide (CdSe) nanoparticles over well aligned ZnO nanorods have been performed using successive ionic layer adsorption and reaction (SILAR) technique at room temperature (27 °C) in order to form nano heterostructure solar cells. Deposition of compact layer of zinc oxide (ZnO) by SILAR technique on fluorine doped tin oxide (FTO) coated glass substrate followed by growth of vertically aligned ZnO nanorods array using chemical bath deposition (CBD) at low temperature (<100 °C). Different characterization techniques viz. X-ray diffractometer, UV-Vis spectrophotometer, field emission scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy have been used to know the structural, optical, morphological and compositional properties of synthesized nano heterostructure. The photovoltaic performance of the cells with variation in SILAR cycles for CdSe and with use of different electrolytes have been recorded as J-V characteristics and the maximum conversion efficiency of 0.63% have been attained with ferro/ferri cyanide electrolyte for 12 cycles CdSe coating over 1-D ZnO nanorods.