Six new dyes based on phenothiazine conjugated to an ethynyl-pyrene moiety are synthesized and characterized.

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In this study, photo-physical properties of five N-annulated perylene (NP) based metal free organic D-p-A (donor-p-linkeracceptor) sensitizers for dye-sensitized solar cells (DSSCs) have been investigated by using density functional theory (DFT/ B3LYP/6-31G (d)). These dyes contain triphenylamine (TPA) derivative linked to the NP, thiophene and 2-cyanoacetic acid as electron donor, conjugated linker and acceptor. Effect of TPA, substituted TPA and the of linker on the highest occupied molecular orbital, lowest unoccupied molecular orbital and bandgap energy of these compounds have been calculated and compared against experimental values reported. The electronic absorption spectra of these dyes are studied by time-dependent density functional theory calculations. Based on the calculations, (E)-2-cyano-3-(10-(4-(diphenylamino) phenyl)-1-(2-ethylhexyl)-1H-phenanthro [1,10,9,8] carbazol-3-yl) acrylic acid (NPS-4) is identified as best dye for the DSSCs operating with I 3 À /I À containing electrolyte. Furthermore, chemical hardness and reorganization energy of the dyes have been calculated and analyzed, whose values predicted the electron injection ability of the dyes and hence short-circuit current density. Although, all five dyes were capable of injecting electron into the conduction band of TiO 2 , the highest driving force for dye regeneration, the lowest reorganization energy and the highest open-circuit voltage of the NPS-4 makes it most suitable for the DSSC application.

Increase in surface coverage by oxygen reduction reaction intermediates with increase in overpotential impeding diffusion of oxygen to the electrode surface.

In this paper, we report the fluorescence properties of new star α-cyanostilbene molecules. Fungus cell imaging studies using one of the molecules allowed observing nuclear movement in the live mycelium.

A photoactive electrode comprising lead sulfide (PbS) and cadmium sulfide (CdS) quantum dots (QDs) and functionalized graphite platelets (FGPs) was prepared by assembling them onto titanium dioxide (TiO2), which functioned as the wide band gap semiconducting scaffold. The QDs were cumulatively capable of harvesting portions of visible and infrared regions of solar spectrum, and FGP served as electron conduit. Graphite platelets (GPs) were noncovalently functionalized using 1-pyrenecarboxylic acid (PCA) to yield FGP. The insertion of PCA between GP layers to yield few-layer graphene or FGP was confirmed by high-resolution transmission electron microscopy and Raman and X-ray photoelectron spectroscopic analyses. Fluorescence quenching, emission decay analyses, and energetics of the TiO2/FGP/PbS/CdS electrode demonstrated excited electron deactivation via a cascade mechanism. Photoexcited electrons propagate from PbS to CdS to TiO2 and to the external circuit through FGP, which had a suitably poised Fermi level at 4.52 eV. The role of FGP in working as an efficient electron acceptor and PbS as a red wavelength absorbing layer was evidenced in the form of enhanced external and internal quantum efficiencies achieved for the TiO2/FGP/PbS/CdS electrode over the entire solar spectrum compared with the TiO2/CdS electrode. This was accomplished using cells with Sn 2–/S2– as the redox couple and a multiwalled carbon nanotube-based counter electrode. The best overall power conversion efficiency of the TiO2/FGP/PbS/CdS photoanode-based cell is 3.82%, which is greater by 54% compared with that of the TiO2/CdS cell. Our studies demonstrate the prowess of using a near-infrared absorber like PbS and an electron acceptor like FGP in realizing remarkable improvements in solar-cell performance metrics.

Non-precious metal electrocatalysts obtained by pyrolysis of precursors of metal, nitrogen, and carbon (MNC) are viewed as an inexpensive replacement for platinum-based electrocatalysts for the oxygen reduction reaction (ORR) in fuel cells. The hypothesized ORR active site structure of typical MNC catalysts consists of a transition metal coordinated to the pyridinic/pyrollic type of nitrogen covalently attached to the edges of the graphitic crystallites. One of the drawbacks of all the reported procedures to synthesize these MNC electrocatalysts is the inability to control the formation of a specific active site structure suitable for ORR. Lack of clarity on the active site structure limits the researcher's ability to design a synthesis methodology that maximizes the specific active site density. In this study, we have synthesized a Co(III) dimer ([Co 2 (OH) 2 (OOCCH 3 ) 3 (bpy) 2 ] NO 3 ⋅ 1.5 H 2 O) and demonstrated its ORR activity in alkaline medium. The ORR activity and methanol tolerance property of the Co(III) dimer were compared with those of Ketjenblack carbon (used as support for Co(III) dimer) and commercial 20 wt% Pt/C, respectively. Since Co(III) dimer is a molecular material, its characterization by single-crystal X-ray diffraction, nuclear magnetic resonance, and infrared studies revealed the chemical structure unambiguously. Density functional theory calculation predicted the possibility of both end-on and side-on oxygen adsorption at the metal center of the Co(III) dimer.