Fabrication and characterization of dye sensitized solar cells: A photographic guide

This paper presents the detailed fabrication procedure of dye-sensitized solar cells. The characterization techniques used for evaluating solar cell performance have also been described. The photographs of the fabrication process and characterization systems have been provided wherever necessary. Important fabrication steps which have not been provided in detail in the scientific literature have been presented for clarity. Proper characterization methodology has been provided to correctly evaluate the performance of solar cells. The general procedures and techniques presented here can also be used for fabricating efficient perovskite solar cells. Present work can be used as a guide for fabricating and characterizing high efficiency dye sensitized solar cells, and will be very useful for the researchers engaged in solar cell research work

Plasmonic Molecular Nanohybrids—Spectral Dependence of Fluorescence Quenching

We demonstrate strong spectral dependence of the efficiency of fluorescence quenching in molecular systems composed of organic dyes and gold nanoparticles. In order to probe the coupling with metallic nanoparticles we use dyes with varied spectral overlap between the plasmon resonance and their absorption. Hybrid molecular structures were obtained via conjugation of metallic nanoparticles with the dyes using biotin-streptavidin linkage. For dyes featuring absorption above the plasmon excitation in gold nanoparticles, laser excitation induces minute changes in the fluorescence intensity and its lifetime for both conjugated and non-conjugated mixtures, which are the reference. In contrast, when the absorption of the dye overlaps with the plasmon resonance, the effect is quite dramatic, reaching 85% and 95% fluorescence quenching for non-conjugated and conjugated mixtures, respectively. The degree of fluorescence quenching strongly depends upon the concentration of metallic nanoparticles. Importantly, the origin of the fluorescence quenching is different in the case of the conjugated mixture, as evidenced by time-resolved fluorescence. For conjugated mixtures of dyes resonant with plasmon, excitation features two-exponential decay. This is in contrast to the single exponential decay measured for the off-resonant configuration. The results provide valuable insight into spectral dependence of the fluorescence quenching in molecular assemblies involving organic dyes and metallic nanoparticles

Bi-Functional Silica Nanoparticles Doped with Iron Oxide and CdTe Prepared by a Facile Method

Cadmium telluride (CdTe) and iron oxide nanoparticles doped silica nanospheres were prepared by a multistep method. Iron oxide nanoparticles were first coated with silica and then modified with amino group. Thereafter, CdTe nanoparticles were assembled on the particle surfaces by their strong interaction with amino group. Finally, an outer silica shell was deposited. The final products were characterized by X-ray powder diffraction, transmission electron microscopy, vibration sample magnetometer, photoluminescence spectra, Fourier transform infrared spectra (FT-IR), and fluorescent microscopy. The characterization results showed that the final nanomaterial possessed a saturation magnetization of about 5.8 emu g−1and an emission peak at 588 nm when the excitation wavelength fixed at 380 nm

Fabrication and characterization of dye sensitized solar cells: A photographic guide

737-744This paper presents the detailed fabrication procedure of dye-sensitized solar cells. The characterization techniques used for evaluating solar cell performance have also been described. The photographs of the fabrication process and characterization systems have been provided wherever necessary. Important fabrication steps which have not been provided in detail in the scientific literature have been presented for clarity. Proper characterization methodology has been provided to correctly evaluate the performance of solar cells. The general procedures and techniques presented here can also be used for fabricating efficient perovskite solar cells. Present work can be used as a guide for fabricating and characterizing high efficiency dye sensitized solar cells, and will be very useful for the researchers engaged in solar cell research work

Effect of Fe and Mn Substitution in LaNiO3 on Exsolution, Activity, and Stability for Methane Dry Reforming

Perovskites LaNi0.8Fe0.2O3 and LaNi0.8Mn0.2O3 were synthesized using the co-precipitation method by substituting 20 mol.% of the Ni-site with Fe and Mn, respectively. Temperature programmed reduction (TPR) showed that the exsolution process in the Fe- and Mn-substituted perovskites followed a two-step and three-step reduction pathway, respectively. Once exsolved, the catalysts were found to be able to regenerate the original perovskite when exposed to an oxygen environment but with different crystallographic properties. The catalytic activity for both materials after exsolution was measured for the methane dry reforming (DRM) reaction at 650 °C and 800 °C. Catalyst resistance against nickel agglomeration, unwanted phase changes, and carbon accumulation during DRM were analyzed using X-ray diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The presence Fe alloying in the catalyst particles after exsolution from LaNi0.8Fe0.2O3 led to a lower methane conversion compared to the catalyst derived from LaNi0.8Mn0.2O3 where no alloying occurred

Role of Textured Silicon Surface in Plasmonic Light Trapping for Solar Cells: The Effect of Pyramids Width and Height

Silicon solar cells with different front texturization are used for understanding pyramidal size influence on plasmonic light trapping. Cells with different pyramidal heights and widths have shown strong light back scattering in the surface plasmon resonance (SPR) region and minimal light forward scattering in the off-resonance region of silver nanoparticles (NPs). On the other hand, cell surface with similar pyramidal heights and widths has shown reduced back scattering in the SPR region, as well as enhanced light forward scattering in the off-resonance region of NPs with good optical impedance matching. The reason for these types of light interaction with NPs (nanoscale) and textured silicon (micrometer-scale) is explained, and plasmonic textured silicon solar cell performance with different pyramidal sizes using quantum efficiency measurements is verified

Structural, optical and magnetic properties of Cr-substituted CeO2 nanoparticles

Nanocrystalline CrxCe1-xO2 (0 <= x <= 0.3) samples were synthesized by a microwave refluxing method. These samples were characterized by X-ray diffractometer, Transmission electron microscope, Raman spectroscopy, UV-Vis spectrometer, Photoluminescence, and X-ray photoelectron spectroscopy. The XRD and TEM analyses indicates the formation of single phase in them. UV-vis spectroscopy results displayed blue shift of absorption peaks with increased Cr content. Magnetic measurements showed initial increase followed by decrease of saturation magnetization (M-s) with increasing doping concentration. The Ms value of x = 0.05 is nearly four times larger than that of undoped CeO2. This initial enhancement of Ms has been attributed to the creation of oxygen vacancies. The decrease in Ms at higher concentrations, has been corroborated with the appearance of antiferromagnetic interaction above a threshold value of Cr3+ content which is lying between x = 0.05 and 0.1. (C) 2016 Elsevier B.V. All rights reserved

Efficient antibacterial activity via protein degradation of a 3D layered double hydroxide-reduced graphene oxide nanohybrid

Graphene and its derivatives have typical physicochemical properties that show strong cytotoxic effects on bacterial cell lines. In this study, we have investigated the antibacterial activity of a nanohybrid of three-dimensional Mg-Al layered double hydroxide-reduced graphene oxide (LDH-rGO) on the Gram negative coccobacilli bacterium Escherichia coli (E. coli). A biocompatibility test by a sulphorhodamine-B (SRB) assay inferred that LDH-rGO is biocompatible up to a concentration of 2 mg mL(-1). The concentration and time-dependent antibacterial studies confirmed that 125 mg mL(-1) of LDH-rGO is sufficient to inhibit 95.4 +/- 1.1% E. coli cells in 60 min. A systematic study shows that the nanohybrid is capable of developing oxidative stress by producing reactive oxygen species (ROS), while LDH and rGO does not. However, both rGO and the nanohybrid are capable of developing oxidative stress by oxidizing glutathione. Further, the effect of oxidative stress on one of the biological entities (protein) of E. coli was also studied. We thereby propose the antibacterial mechanism of the nanohybrid on the basis of size, morphology, glutathione loss, and protein degradation

Internal quantum efficiency analysis of plasmonic textured silicon solar cells: surface plasmon resonance and off-resonance effects

Silver nanoparticles (Ag NPs) of various sizes and concentration were integrated on textured silicon solar cells for further confinement of incident light, generated photocurrent modifications were investigated using spectrally resolved short-circuit current measurements. Internal quantum efficiency (IQE) spectra were used for quantifying the effective minority carrier diffusion lengths (Le(ff)) of plasmonic cells in the long wavelength region (850 < lambda < 1020 nm). The L-eff of an optimized plasmonic solar cell enhanced to 431 mu m compared to 338 mu m of the bare cell, which is due to interacting Ag NPs' scattered fields, leading to enhanced light absorption in the plasmonic cell. Despite the enhanced L-eff values, the overall generated photocurrent reduced with Ag NPs which is due to the significant losses near the surface plasmon resonant region. Reduced IQE of plasmonic cells near and below the surface plasmon resonant region is due to size-dependent parasitic absorption and enhanced back scattering of Ag NPs, and a modified surface recombination process due to Ag NPs' strong near-fields