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In this study, synthesis of nanosized TiO2 in which hydrolysis and polycondensation of precursor, Ti(OC4H9)4, has been performed in presence of different molecular weight polyethylene glycol (PEG) polymer as a capping agent is reported. Three different capped materials (TN-P400, TN-P4000, and TN-P8000) were synthesized along with un-capped TiO2 (TiO2 synthesized without using PEG, TN) for the sake of comparison. The structure and morphology of the synthesized TiO2 were characterized by XRD, FTIR, SEM, and DLS analyses. The X-ray diffraction spectrums show the presence of anatase phase TiO2. The as-synthesized PEG-capped TiO2 were used as photoanode material for dye-sensitized solar cells (DSSC) after coating with sensitizer dye N719, and photoelectric conversion efficiency (PCE) of 2.52%, under the illumination of 100 mW cm−2, has been achieved with TN-P8000, which was much improved compared with DSSC performance with un-capped TiO2 (PCE = 1.02%). EIS analyses revealed that TN-P8000 photoanode–based cell exhibited facile charge transfer, enhanced electron lifetime, and greater charge collection efficiency that contributed better photovoltaic performance. The results demonstrated that using PEG as a capping agent is a potential approach for improving the efficiency of DSSC and current conversion efficiency was increased as the molecular weight of PEG was increased. [ABSTRACT FROM AUTHOR]

New homoleptic copper(II) dithiocarbamate complexes, [Cu(L1‐L5)2] (L1=N‐benzyl‐N‐4‐bromobenzyl dithiocarbamate−Cu1; L2=N‐benzyl‐N‐4‐methoxybenzyl dithiocarbamate−Cu2; L3=4‐N,N‐diethylbenzyl‐N‐methyl dithiocarbamate−Cu3; L4=N‐methyl‐N‐4‐isopropylbenzyl dithiocarbamate−Cu4 and L5=N‐3‐pyridyl‐N‐4‐bromobenzyl dithiocarbamate−Cu5) have been synthesized and characterized by elemental analysis, HRMS, IR and UV‐Vis. spectroscopy, PXRD and cyclic voltammetry. The monomeric (1−3) and dimeric (4) structures have been elucidated by X‐ray crystallography. In all four structures the copper atom has square planar geometry. In 3 and 4 existence of rare C−H⋅⋅⋅Cu intermolecular anagostic interactions have been detected in the solid state. All complexes were exploited as sensitizers for TiO2 photoanode based dye‐sensitized solar cells (DSSC). When TiO2 anchored with these complexes was used as DSSC photoanode, significant light harvesting properties were observed with an exceptionally high light‐to‐electrical energy conversion efficiency (3.62%) shown by Cu3 complex. The extent of interfacial charge‐recombination and electron lifetime was evaluated from the electrochemical impedance spectroscopy (EIS) studies. The better performance of Cu3 compared to other complexes was attributed to its structural features. All the complexes with σrt, 10−6‐10−9 S cm−1 are weakly conducting but show semiconducting behaviour in the 303–383 K temperature range with Ea values of 0.20−0.90 eV. [ABSTRACT FROM AUTHOR]

Abstract: The performance of TiO2 based dye‐sensitized solar cells (DSSCs) is largely influenced by the size of the TiO2 particles. In this work, different‐sized TiO2 nanoparticles have been synthesized by a facile sol–gel technique using polyethylene glycol (PEG) as capping agent and its performance as the photoanode of DSSC with N719 sensitizer dye is investigated. Particle nature and dimension of TiO2 nanoparticles were studied through XRD, FTIR, SEM and dynamic light scattering (DLS) analyses, whereas thermal stability was investigated through TGA in the temperature range of 30–600 °C 30–600 °C. The DSSC assembled with photoanode consisted of smallest size TiO2 nanoparticles obtained using 3 mM PEG (TNP‐II) exhibited solar‐to‐electrical energy conversion efficiency of 2.5%, under illumination of 100 mWcm−2, which was an extensive improvement compared to the device based on un‐capped, TiO2 nanoparticles based cell (TNP) (1.0%). The enhancement in efficiency resulting from the reduction of particles size of TiO2 is attributed to enlarged band‐gap, increased specific surface area & surface to volume ratio of the photoanode, greater dye loading and more interactions between anchoring groups of the dye and surface of TiO2.EIS measurements revealed that TNP‐II photoanode–based cells exhibited faster electron transport, increased electron lifetime, higher charge collection efficiency and less recombination leading to better photovoltaic output. The work shows that developed TNP‐II nanoparticles have good potential for application in photoenergy conversion devices. [ABSTRACT FROM AUTHOR]

Natural dyes extracted from four different flowers, namely, Cassia surattensis, Cassia tora, Cassia alata and Cassia occidentalis were used as sensitizers for TiO-based dye-sensitized solar cells (DSSC). The dye extracts from flowers were obtained by a simple extraction technique and used without any further purification. Optical characteristics of dye extracts were studied. Fourier-transform infrared (FTIR) spectra were used to identify the constituents of extracted dyes. The photovoltaic performance of DSSC employing dye-capped TiO photoanodes was measured. The sensitization performance related to anchoring groups present and interaction between dyes with TiO surface is demonstrated. An attempt has been made to rationalize the observations by light absorption of the dye extracts and their adsorption on TiO. The short-circuit current density ( I ) values ranged from 0.06 mA/cm to 0.20 mA/cm; open circuit voltage ( V ) from 0.292 V to 0.833 V; fill factor (FF) from 0.7 to 0.9; efficiencies ( η) from 0.013% to 0.15% and incident photon-to-current conversion efficiency from 13% to 20%, were obtained for DSSC using these natural dye extracts. Cassia occidentalis showed the highest current density of 0.20 mA/cm and power conversion efficiency of 0.15%, which was due to better interaction between the carbonyl and hydroxyl group of the anthocyanin molecule of C. occidentalis and surface of TiO film. The red and blue shift of absorption wavelength of C. surattensis and the blue shift of absorption wavelength of the C. tora, C. alata and C. occidentalis extract in ethanol solution compared to that on TiO film has been used for the interpretation of obtained results. [ABSTRACT FROM AUTHOR]

Green chemistry technologies are perceived to be more straightforward, sustainable and cost-effective and therefore explored extensively in recent years. A range of natural reducing and capping agents, viz. proteins, enzymes, and phytochemicals have been used to synthesize TiO 2 nanoparticles. The capping agents are vital in stabilizing nanoparticles, avoiding their over-growth and aggregation during synthesis. In this work, green synthesis of TiO 2 has been carried out through the sol-gel method using Saccharum officinarum (sugarcane) juice as a capping agent. The optical properties, morphology, size, and porosity of the synthesized TiO 2 were characterized by UV, FT-IR, XRD, TEM, and BET respectively. The XRD pattern and TEM confirmed the anatase phase and particle size, while BET revealed surface area and pore sizes. Under irradiance of 100 mWcm−2 light intensity, the photoelectric conversion efficiency using capped TiO 2 sensitized with N719 dye was observed to 3.65 %, much enhanced compared to the efficiency 0.69 % observed with the un-capped TiO 2. The present study successfully demonstrated that sugarcane phytochemicals have the potential to improve dye-sensitized solar cell (DSSC) efficiency via inducing capping during nucleation in TiO 2 synthesis. [Display omitted] • Green synthesis of TiO 2 utilizing Saccharum officinarum (sugarcane) juice as a capping agent. • Efficiency enhancement attributed to the increased surface area, pore diameter, and pore volume for the capped TiO 2 compared to the un-capped TiO 2. • Better dye loading and charge transfer properties, resulted in the improved J sc and hence increased overall photovoltaic performances. [ABSTRACT FROM AUTHOR]

• Nd-TiO 2 having Anatase and Brookite phases at high temperature by hydrothermal method. • Higher efficiency DSSC with TiO 2 Anatase and Brookite structure mixed photoanode. • Nd-TiO 2 photoanode based cell exhibiting significantly enhanced cell efficiency. • Nd-TiO 2 exhibiting increased dye loading and facile charge transfer characteristics. In this study, the effects of Nd doping on the performance of TiO 2 photoanode based dye-sensitized solar cells (DSSC) are reported. Nd-doped TiO 2 (Nd-TiO 2) was synthesized using hydrothermal method. Un-doped TiO 2 (TiO 2) was also synthesized for reference. XRD, IR, Raman and electron microscopy characterisation of the obtained material were performed and the subsequent electrochemical tests, CV and EIS studies were made to explore their application. The XRD and Raman analysis's results indicated that the Nd-TiO 2 and TiO 2 have both the Anatase and Brookite phases. TEM, EDX and EIS studies were used to obtain particle size, morphology, the presence of the element, electron lifetime and recombination characteristics respectively. The Nd-TiO 2 nanoparticles have uniform particle size, a strong red shift of their absorption into the visible region and greater dye-loading as compared with TiO 2 nanoparticles. It is proved that higher efficiency was achieved when the TiO 2 Anatase and Brookite structure were mixed. Further, Nd had a positive effect on the performance of photoelectrode and DSSC fabricated with Nd-TiO 2 photoanode revealed an appreciable current conversion efficiency of 5.23% with a short-circuit current (J sc) of 12.8 mA/cm2, open-circuit voltage (V oc) of 0.62 V and fill factor (FF) of 0.66. The increased current conversion efficiency was attributed to the greater dye loading, reduced charge recombination and facile charge transport with Nd-doped TiO 2. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • New d10 metal complexes studied for sensitization activities in TiO 2 based DSSC. • High efficiency (6.2%) of Zn- 1 based cell, close to that obtained with N719 (6.9%). • Zn- 1 demonstrated better output due to structural features, greater dye coverage and longer electron life time. Abstract Four synthesized d10 metal complexes, namely, ferrocenyl based pyridyl functionalized dithiocarbamates macro-cyclic metal-organic coordination polymers, [M(L) 2 ] ∞ (M = Zn(II), L = (N-ferrocenyl-methyl-N-pyridin-4-ylmethyl)dithiocarbamate Zn- 2 ; Cd (II), L = (N-ferrocenyl-methyl-N-pyridin-3-ylmethyl) dithiocarbamate Cd- 3 and dimers [M(L) 2 ] 2 (M = Zn(II), Hg(II), L = (N-ferrocenyl-methyl-N-pyridin-3-ylmethyl) dithiocarbamate, Zn- 1 and Hg- 4 were studied for their sensitization activities when anchored on TiO 2 thin film electrode and employed as photoanode in dye-sensitized solar cells (DSSC). The absorption spectra of test dyes in dichloromethane solution indicated absorption in 400–500 nm range for all complexes, revealing the possibility of their use as photosensitizers for TiO 2. The cyclic voltammetry (CV) demonstrated quasi-reversible behavior for all the complexes. All the dye sensitizers showed significant light harvesting properties with an exceptionally high light-to-electrical energy conversion efficiency (6.23%) shown by Zn- 1 complex which was close to that obtained with standard Ru dye, N719 (6.96%) under similar experimental conditions. The better performance of Zn- 1 complex compared to other studied dye sensitizers were attributed to its structural features. The extent of interfacial charge recombination and electron lifetime were evaluated by the electrochemical impedance spectroscopy (EIS). [ABSTRACT FROM AUTHOR]

We describe here in significance of tannic acid in obtaining size dependent electrochemically active and magnetic gold nanoparticles (GNPs). In this account, two types of GNPs (SCGNPs and SC-TAGNPs) were synthesized by using sodium citrate and sodium citrate-tannic acid as reducing agents, respectively. Highly monodispersed, uniformly distributed and small size GNPs were produced when tannic acid was used together with sodium citrate. SC-TAGNPs exhibited room temperature ferromagnetism while SCGNPs revealed diamagnetism. With higher anodic peak current and lower charge transfer resistance, the SC-TAGNPs exhibited better conductivity and electron transfer ability than SCGNPs. Mott-Schottky analysis revealed n-type semiconducting behavior of GC/SCGNPs & GC/SC-TAGNPs and showed positive shift in flat-band potential of GC/SC-TAGNPs compared to GC/SCGNPs suggesting better conductivity of SC-TAGNPs. Subsequently, SCGNPs and SC-TAGNPs were added to TiO 2 nanoparticles to fabricate modified titania photoanodes (SCGNPs@TiO 2 and SC-TAGNPs@TiO 2) for dye-sensitized solar cells (DSSCs) application. With the use of TiO 2 , SCGNPs@TiO 2 and SC-TAGNPs@TiO 2 photoanodes, the short-circuit current density (J SC) was observed to be 2.18, 4.50 and 6.68 mA/cm2, while energy conversion efficiency (η) was found to be 0.75, 1.74 and 2.50%, respectively. The TiO 2 photoanode employing SC-TAGNPs exhibited remarkably increased J SC and η by ∼48 and ∼44%, respectively, then SCGNPs modified photoanode. [Display omitted] • Synthesis of SCGNPs and SC-TAGNPs using sodium citrate and sodium citrate-tannic acid, respectively as reducing agents. • Highly monodispersed, uniformly distributed and smaller size of SC-TAGNPs (⁓4.5 nm) compared to SCGNPs (⁓10 nm). • Better conductivity and electron transfer ability of GC/SC-TAGNPs compared to GC/SCGNPs. • Better magnetic property of SC-TAGNPs than that of SCGNPs. • Enhancement of J SC and η by ∼48 and ∼44%, respectively, of SC-TAGNPs@TiO 2 compared to that of SCGNPs@TiO 2 in DSSC. [ABSTRACT FROM AUTHOR]