Enhancement of TiO2 nanoparticle properties and efficiency of dye-sensitized solar cells using modifiers

A low-temperature hydrothermal process developed to synthesizes titania nanoparticles with controlled size. We investigate the effects of modifier substances, urea, on surface chemistry of titania (TiO) nanopowder and its applications in dye-sensitized solar cells (DSSCs). Treating the nanoparticles with a modifier solution changes its morphology, which allows the TiO nanoparticles to exhibit properties that differ from untreated TiO nanoparticles. The obtained TiO nanoparticle electrodes characterized by XRD, SEM, TEM/HRTEM, UV-VIS Spectroscopy and FTIR. Experimental results indicate that the effect of bulk traps and the surface states within the TiO nanoparticle films using modifiers enhances the efficiency in DSSCs. Under 100-mW cm simulated sunlight, the titania nanoparticles DSSC showed solar energy conversion efficiency = 4.6 %, with V = 0.74 V, J = 9.7324 mA cm, and fill factor = 71.35

Hydrothermal Preparation of Gd+3 -Doped Titanate Nanotubes: Magnetic Properties and Photovoltaic Performance

Pure and Gd+3 -doped titanate nanotubes (TNTs) materials were synthesized by a hydrothermal method. Their morphology, optical properties, thermal stability, and magnetic properties were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), UV-Vis spectroscopy, thermal analysis, and magnetic measurements. It was found that doping renders Gd+3-TNT visible light active and results in smaller crystallite size and larger surface area as well as higher thermal stability compared to pure titanate nanotubes. The estimated magnetic moments point to presence of weak antiferromagnetic interaction. Application of the prepared Gd+3-TNT for modifying conventional photoanodes in polymer solar cells was attempted. Preliminary results show slightly improved photovoltaic energy conversion efficiency in the devices containing the newly designed Gd+3 -doped nanotubes

Titanium dioxide nanomaterial doped with trivalent lanthanide ions of Tb, Eu and Sm: Preparation, characterization and potential applications

Mesoporous Ln(III)–TiO 2 (Ln = Tb, Eu, Sm) nanomaterials composites have been successfully synthesized and characterized. The absorption spectra reflect the increasing photoresponse of doped samples to visible light over pure TiO 2. Surface area is remarkably increased due to lanthanide ion-doping. In this paper, we report on the properties of this new class of nanomaterials in view of their possible profitable applications in light-emitting devices and photocatalysis. Mesoporous Ln(III)–TiO 2 (Ln = Tb, Eu, Sm) nanomaterials composites have been successfully synthesized by using sol–gel technique. XRD pattern, FT-IR, Raman spectra, and SEM were used to characterize the Ln(III)–TiO 2 nanomaterials. The prepared lanthanide doped TiO 2 nanomaterials have anatase phase and exhibit Ti–O–Ln bond. The absorption spectra of all prepared samples reflect the increasing photoresponse of doped samples to visible light over pure TiO 2. Surface area is remarkably increased due to lanthanide ion-doping. Two newly prepared Ln(III)–TiO 2 (Ln = Eu, Sm) luminescent nanomaterials exhibit enhanced pure red or orange light emission due to energy transfer from host TiO 2 to guest Eu(III) or Sm(III), respectively. In addition, the commercially available textile dye Remazol Red RB-133 degradation was used as a probe reaction to determine the efficiency of the Ln(III)–TiO 2 photocatalysts. The Ln(III) doping brought about remarkable improvement in the photoactivity over pure TiO 2

Non-radiative deactivation channels of molecular rotors

On the basis of the fluorescence properties of a series of intramolecular charge-transfer complexes of varied structure ( p-( N, N-dialkylamino) benzylidene malononitriles and coumarin laser dyes) in an inert solvent (ethyl acetate), a model of non-radiative decay is proposed. The model specifically describes the relative contributions of the possible internal relaxation channels to non-radiative energy dissipation of the S 1, ct states via the free rotor mechanism. The results are consistent with the theoretical predictions based on the calculated electron density distributions and the bond-order alternation in the S 1, ct state

Fluorescence properties of surface-active styrylcyanine molecular rotors

This paper reports on some photophysical properties of a newly synthesized styrylcyanine chromogen 1 of electron donor—acceptor type, namely 1-cetyl-4-[4′-( N- N-dimethylamino)-styryl]-pyridinium bromide. The fluorescence properties of this self-organized surfactant chromogen were studied in non-homogeneous media. Its fluorescence shows a sensitivity to environmental factors which could be exploited profitably as a fluorescence probe in various systems of industrial and biological importance. A remarkable enhancement in its fluorescence efficiency was observed in a rigid ethanol matrix at 77 K and in micellar solutions. Moreover, a considerable edge-excitation red shift was observed in a PMMA matrix at room temperature similar to that found in glassy ethanol. The results provide some information on the free-volume distribution in a PMMA matrix. The changes noted can be rationalized, relative to the short-chain model compound 2 in terms of an enhanced sensitivity of the highly organized and tightly packed molecules 1 to viscocity—torsional reactions between solute and solvent

Photostability of low cost dye-sensitized solar cells based on natural and synthetic dyes

Anthocyanin dye showed the maximum current efficiency η=0.27% •Application of natural pigments and synthetic dye sensitizers in dye-sensitized solar cells (DSSCs).•Photostability of the dyes over the TiO2 film electrodes.•The stability results favor selecting anthocyanin as a promising sensitizer candidate for DSSCs applications. This paper deals with the use of some natural pigments as well as synthetic dyes to act as sensitizers in dye-sensitized solar cells (DSSCs). Anthocyanin dye extracted from rosella (Hibiscus sabdariffa L.) flowers, the commercially available textile dye Remazole Red RB-133 (RR) and merocyanin-like dye based on 7-methyl coumarin are tested. The photostability of the three dyes is investigated under UV–Vis light exposure. The results show a relatively high stability of the three dyes. Moreover, the photostability of the solid dyes is studied over the TiO2 film electrodes. A very low decolorization rates are recorded as; rate constants k=1.6, 2.1 and 1.9×10−3min−1 for anthocyanin, RR and coumarin dyes, respectively. The stability results favor selecting anthocyanin as a promising sensitizer candidate in DSSCs based on natural products. Dyes-sensitized solar cells are fabricated and their conversion efficiency (η) is 0.27%, 0.14% and 0.001% for the anthocyanin, RR and coumarin dyes, respectively. Moreover, stability tests of the sealed cells based on anthocyanin and RR dyes are done under continuous light exposure of 100mWcm−2, reveals highly stable DSSCs

Enhancement of TiO2 nanoparticle properties and efficiency of dye-sensitized solar cells using modifiers

A low-temperature hydrothermal process developed to synthesizes titania nanoparticles with controlled size. We investigate the effects of modifier substances, urea, on surface chemistry of titania (TiO) nanopowder and its applications in dye-sensitized solar cells (DSSCs). Treating the nanoparticles with a modifier solution changes its morphology, which allows the TiO nanoparticles to exhibit properties that differ from untreated TiO nanoparticles. The obtained TiO nanoparticle electrodes characterized by XRD, SEM, TEM/HRTEM, UV-VIS Spectroscopy and FTIR. Experimental results indicate that the effect of bulk traps and the surface states within the TiO nanoparticle films using modifiers enhances the efficiency in DSSCs. Under 100-mW cm simulated sunlight, the titania nanoparticles DSSC showed solar energy conversion efficiency = 4.6 %, with V = 0.74 V, J = 9.7324 mA cm, and fill factor = 71.35