Sanjay Sahare

Low temperature and controlled synthesis of Bi2(S1−xSex)3 thin films using a simple chemical route: effect of bath composition

Nanostructured bismuth sulphoselenide (Bi2(S1−xSex)3) thin films have been synthesized using a simple, cost-effective chemical bath deposition (CBD) method at room temperature (300 K). Structural, compositional, morphological and optical characterization and photoelectrochemical performance testing of these Bi2(S1−xSex)3 thin films has been carried out. The X-ray diffraction (XRD) study demonstrates that these thin films are nanocrystalline in nature with pure orthorhombic crystal structures. X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS) show that the deposited thin films are nearly stoichiometric in nature. Field emission scanning electron microscopy (FESEM) reveals different morphologies for the Bi2(S1−xSex)3 thin films. The linear nature of the plots seen in the UV-Vis-NIR absorption study confirms the direct allowed type of transition. J–V measurements with a solar simulator were carried out for all samples and the highest photoconversion efficiency, 0.3845%, has been recorded for the Bi2Se3 thin film. The significant boost in photoelectrochemical (PEC) performance might be due to the larger surface area with lower dislocation density and microstrain with a lower level of grain boundary resistance of Bi2Se3 thin films.

Photon assisted conducting atomic force microscopy study of nanostructured additives in P3HT:PCBM

One of the ways of improving the efficiency of polymer solar cells is to increase the conductive paths in the photoactive layer. The present work focuses on the study of the effect of additives (silver nanoparticles (Ag NPs) and graphene (Gr)) in photoactive poly-3-hexyl thiophene:phenyl-C61-butyric acid methyl ester (P3HT:PCBM). The morphology and localised photocurrent obtained using Photon Assisted Conducting Atomic Force Microscopy reflect the role of these additives in the photocurrent produced by the active layer. The study depicts that the morphology of a P3HT:PCBM film changes completely with Gr additives, whereas a very small change occurs with the addition of Ag NPs. A localised photocurrent measurement exhibits that the space charge limited conduction (SCLC) phenomenon could be the dominant process of charge conduction in the P3HT:PCBM film with additives. The study also demonstrates that the carrier mobility is enhanced by more than an order of magnitude with Gr as the additive. This is a significant change for achieving efficient charge separation and transportation in polymer solar cell application.

Magnetically active micromixer assisted synthesis of drug nanocomplexes exhibiting strong bactericidal potential

In the ever-growing demand for drug nanocomplexes (DNCs), the need for smart systems or processes is indispensable to circumvent the demerits imposed by the conventional methods for the synthesis of DNCs. The demerits include prolonged hours of the synthesis, minimal loading and poor conjugation. Herein, we proposed a simplistic approach for the synthesis of DNCs through a magnetically active Polydimethylsiloxane micromixer which can render maximal loading in an unprecedented time. The UV-Vis, FTIR, and XRD analysis corroborate the proposed mechanism of conjugation of the drug and nanoparticles. The XPS, contact angle and zeta potential measurements revealed the composition, hydrophilicity and surface charges of the synthesized DNCs, respectively. Further, the microscopy images exemplify the encapsulation of the drug. In the antibacterial activity studies, the DNCs substantially inhibited the growth of the Staphylococcus aureus bacteria. FESEM images proved preferential accumulation of DNCs around bacterial cells effectively annihilating them

Enhancing the efficiency of flexible dye-sensitized solar cells utilizing natural dye extracted from Azadirachta indica

The natural dye extracted from Azadirechta indica (neem) was used as a sensitizer in flexible dye-sensitized solar cells (DSSCs). The fabricated DSSC exhibited open circuit voltage of 0.538 V with 2.81% power conversion efficiency (η) in back-illuminated mode which is higher than that reported in the literature. In order to understand the characteristics of DSSC, systematic study of solar cell component materials was carried out. Anatase TiO2 (30–40 nm) nanoparticles were synthesized by DC arc plasma method and deposited electrophoretically on a flexible titanium (Ti) substrate. A platinum-coated polyethylene terephthalate (PET) substrate was used as a counter electrode to construct flexible DSSC. The structural and optical behavior of neem-dye sensitized TiO2 thin film has been studied using x-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy and UV-visible spectroscopy. We have observed that the neem dye gives a very good sensitization effect. In addition, the dye has good prospects as a low-cost and environmental friendly alternative to ruthenium-based sensitizers which are normally used in DSSCs.

Nanocrystalline titanium dioxide sensitised with natural dyes for eco-friendly solar cell application

Indigenously available natural dyes have been used as natural sensitisers for dye-sensitised solar cells (DSSCs) in this study. The chlorophyll extract from Azadirachta indica (Neem) leaves and anthocyanin extract from poinsettia bracts were obtained using ethanol. Nanoparticles of TiO2 having an average size of 80 nm were deposited on fluorine-doped tin oxide (FTO) coated glass using the electrophoretic deposition method. Counter electrode was prepared by spraying conductive graphite over FTO glass substrates. A sandwich-type cell was assembled, and the fill factor and the power conversion efficiency were measured under a light source simulating AM 1.5 with an intensity of 100 mW/cm2. DSSCs containing chlorophyll and anthocyanin exhibited open circuit voltages of 404 and 406 mV with fill factors of 40.1% and 45.8%, respectively. The mixture of the two natural dyes as sensitiser for DSSCs gave the best photovoltaic conversion efficiency of approximately 1%.

Optimisation of Experimental Techniques to Enhance the Efficiency of Polymer Photovoltaic Cell

The idea of generating electricity from plastics itself sounds enthralling, but it is equally challenging to achieve in the lab and then take it to the production level. Polymer Solar Cells (PSCs) have the advantage of lower cost and flexibility but they do suffer from problems like low efficiency and smaller service life which is mainly due to limited absorption spectra, poor charge mobility and the degradation of the polymers. A combination of narrow band donor and fullerene derivative is one of the possible approaches to fabricate a working device. In this work, various experimental techniques have been optimised in order to achieve better efficiency of the PSCs in atmospheric condition. Optimized parameters from polymer mixing ratio, spin coating, annealing and others were used to enhance efficiency of device. Parameters were optimized with the help various techniques viz. Viscometer, Thermo Gravity Analysis, UV-vis spectroscopy, Scanning Electron Microscopy and I-V measurement system. We report 0.76% efficiency in these solar cells, which were fabricated in open atmospheric condition. The as-prepared device showed a good performance with an open-circuit voltage (Voc) 0.74 V, short circuit current (Isc) 0.6 mA, a fill factor (FF) of 35%.

Surfactant modified Bi 2 (S 0.3 Se 0.7 ) 3 nanoflakes for photo electrochemical cell application

The development of new photoactive structures by combining the lower and higher band gap materials with a controlled morphology can result in the efficiency improvement of the photo electrochemical cell. In this work, optimal change in optical, morphological and electrical properties of bismuth sulphoselenide (Bi2(S0.3Se0.7)3) thin films was observed through different surfactant assisted synthesis procedures. Chemical bath deposition method was implemented to synthesize surfactant assisted nano crystalline Bi2(S0.3Se0.7)3 thin films at room temperature. All these thin films were characterized for their optoelectronic properties by UV–Vis and FTIR spectoscopy, structural properties by X-ray diffraction; and surface and morphological properties by Field emission scanning electron and atomic force microscopy respectively. Photo conversion efficiency of photo electrochemical cell was observed through J–V measurement technique under standard conditions. Among all surfactants, sodium dodecyl sulphate assisted Bi2(S0.3Se0.7)3 thin films exhibited better photo electrochemical conversion efficiency.

Effect of Copper Doping on Physical Properties of Cadmium Oxide Thin Films

Nanostructured materials have generated considerable interest owing to their physical and chemical properties that differ from those of their bulk counterparts. Cadmium oxide (CdO) is an important semiconducting material with varying band gap from 2.2 to 2.9 eV used for various applications. Due to its high electrical conductivity and optical transmittance in the visible region, this material is having potential application in photovoltaic devices as well. This study focuses on the preparation and characterization of CdO (undoped and 2 % Cu-doped) produced by facile sol–gel spin coating. Effect of Cu doping on the structural, optical and morphological properties of CdO have been studied.

Optical fiber sensor based on hybrid material: Comparative study of theoretical model and fabricated sensor

The main intention to present this work is to analyze the theoretical aspect of the optical fiber based relative humidity sensor. The sensor was fabricated using layer by layer (LbL) deposition on the tip of the optical fiber. Corresponding results of fabricated relative humidity sensor using different material like SiO2, ZnO and Hybrid material were compared with theoretical results. A comprehensive experimental investigation was carried out to examine the sensing response. Sensing studies were performed by Fabry-Perot sensing mechanism with different saturated salt solutions, which provide fixed relative humidity.