Simona Fantacci

Bio: Simona Fantacci is an academic researcher from University of Perugia. The author has contributed to research in topics: Time-dependent density functional theory & Dye-sensitized solar cell. The author has an hindex of 41, co-authored 105 publications receiving 9735 citations. Previous affiliations of Simona Fantacci include Istituto Italiano di Tecnologia & École Polytechnique Fédérale de Lausanne.

Combined Experimental and DFT-TDDFT Computational Study of Photoelectrochemical Cell Ruthenium Sensitizers

Abstract: We report a combined experimental and computational study of several ruthenium(II) sensitizers originated from the [Ru(dcbpyH2)2(NCS)2], N3, and [Ru(dcbpyH2)(tdbpy)(NCS)2], N621, (dcbpyH2 = 4,4‘-dicarboxy-2,2‘-bipyridine, tdbpy = 4,4‘-tridecyl-2,2‘-bipyridine) complexes. A purification procedure was developed to obtain pure N-bonded isomers of both types of sensitizers. The photovoltaic data of the purified N3 and N621 sensitizers adsorbed on TiO2 films in their monoprotonated and diprotonated state, exhibited remarkable power conversion efficiency at 1 sun, 11.18 and 9.57%, respectively. An extensive Density Functional Theory (DFT)−Time Dependent DFT study of these sensitizers in solution was performed, investigating the effect of protonation of the terminal carboxylic groups and of the counterions on the electronic structure and optical properties of the dyes. The calculated absorption spectra are in good agreement with the experiment, thus allowing a detailed assignment of the UV−vis spectral features ...

Molecular engineering of organic sensitizers for solar cell applications.

Abstract: Novel organic sensitizers comprising donor, electron-conducting, and anchoring groups were engineered at molecular level and synthesized. The functionalized unsymmetrical organic sensitizers 3-{5-[N,N-bis(9,9-dimethylfluorene-2-yl)phenyl]-thiophene-2-yl}-2-cyano-acrylic acid (JK-1) and 3-{5'-[N,N-bis(9,9-dimethylfluorene-2-yl)phenyl]-2,2'-bisthiophene-5-yl}-2-cyano-acrylic acid (JK-2), upon anchoring onto TiO2 film, exhibit unprecedented incident photon to current conversion efficiency of 91%. The photovoltaic data using an electrolyte having composition of 0.6 M M-methyl-N-butyl imidiazolium iodide, 0.04 M iodine, 0.025 M LiI, 0.05 M guanidinium thiocyanate, and 0.28 M tert-butylpyridine in a 15/85 (v/v) mixture of valeronitrile and acetonitrile revealed a short circuit photocurrent density of 14.0 +/- 0.2 mA/cm2, an open circuit voltage of 753 +/- 10 mV, and a fill factor of 0.76 +/- 0.02, corresponding to an overall conversion efficiency of 8.01% under standard AM 1.5 sunlight. DFT/TDDFT calculations have been performed on the two organic sensitizers to gain insight into their structural, electronic, and optical properties. Our results show that the cyanoacrylic acid groups are essentially coplanar with respect to the thiophene units, reflecting the strong conjugation across the thiophene-cyanoacrylic groups. Molecular orbitals analysis confirmed the experimental assignment of redox potentials, while TDDFT calculations allowed assignment of the visible absorption bands.

Theoretical studies on anatase and less common TiO2 phases: bulk, surfaces, and nanomaterials.

Abstract: Surfaces, and Nanomaterials Filippo De Angelis,† Cristiana Di Valentin,‡ Simona Fantacci,† Andrea Vittadini, and Annabella Selloni* †Computational Laboratory for Hybrid Organic Photovoltaics (CLHYO), Istituto CNR di Scienze e Tecnologie Molecolari, Via Elce di Sotto 8, I-06123 Perugia, Italy ‡Dipartimento di Scienza dei Materiali, Universita ̀ di Milano-Bicocca, I-20125 Milano, Italy Istituto CNR per l’Energetica e le Interfasi (IENI), c/o Dipartimento di Scienze Chimiche, Universita’ di Padova, I-35131 Padova, Italy Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States

Influence of the Sensitizer Adsorption Mode on the Open-Circuit Potential of Dye-Sensitized Solar Cells

Abstract: We report a combined experimental and theoretical study on the origin of the different open circuit potentials observed in dye-sensitized solar cells using Ru(II)-polypyridyl homoleptic and heteroleptic sensitizers. We have measured the photovoltaic data of different sensitizers and used DFT calculations to analyze the electronic structure of dye-sensitized TiO2 nanoparticles. Heteroleptic sensitizers adsorb onto TiO2 via a single bipyridine, leading to a TiO2 conduction band downshift and overall reduction of the cell open circuit potential.

Absorption spectrum and solvatochromism of the [Ru(4,4'-COOH-2,2'-bpy)2(NCS)2] molecular dye by time dependent density functional theory.

Abstract: We present a combined Density Functional/Time Dependent Density Functional study of the molecular structure, electronic states, and optical absorption spectrum of [Ru(4,4‘-COOH-2,2‘-bpy)2(NCS)2], a widely used charge-transfer sensitizer in nanocrystalline TiO2 solar cells. Calculations have been performed both for the complex in vacuo and in ethanol and water solvents, using a continuum model to account for solute−solvent interactions. Inclusion of the solvent leads to important changes of the energies and composition of the molecular orbitals of the complex; as a consequence, whereas the computed spectrum for the Ru-complex in vacuo deviates from the experimental one in both energy and shape, the spectra calculated in the presence of the solvent are in good agreement with the experiment. The first two absorption bands are found to originate from mixed ruthenium-NCS to bipyridine-π* transitions rather than to pure metal-to-ligand-charge-transfer (MLCT) transitions, whereas the third band arises from intra...

Phd by thesis

Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Dye-Sensitized Solar Cells

Abstract: Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. DSC research groups have been established around the worl ...

Semiconductor-based Photocatalytic Hydrogen Generation

Abstract: 2.3. Evaluation of Photocatalytic Water Splitting 6507 2.3.1. Photocatalytic Activity 6507 2.3.2. Photocatalytic Stability 6507 3. UV-Active Photocatalysts for Water Splitting 6507 3.1. d0 Metal Oxide Photocatalyts 6507 3.1.1. Ti-, Zr-Based Oxides 6507 3.1.2. Nb-, Ta-Based Oxides 6514 3.1.3. W-, Mo-Based Oxides 6517 3.1.4. Other d0 Metal Oxides 6518 3.2. d10 Metal Oxide Photocatalyts 6518 3.3. f0 Metal Oxide Photocatalysts 6518 3.4. Nonoxide Photocatalysts 6518 4. Approaches to Modifying the Electronic Band Structure for Visible-Light Harvesting 6519

Porphyrin-Sensitized Solar Cells with Cobalt (II/III)–Based Redox Electrolyte Exceed 12 Percent Efficiency

Abstract: The iodide/triiodide redox shuttle has limited the efficiencies accessible in dye-sensitized solar cells. Here, we report mesoscopic solar cells that incorporate a Co(II/III)tris(bipyridyl)–based redox electrolyte in conjunction with a custom synthesized donor-π-bridge-acceptor zinc porphyrin dye as sensitizer (designated YD2-o-C8). The specific molecular design of YD2-o-C8 greatly retards the rate of interfacial back electron transfer from the conduction band of the nanocrystalline titanium dioxide film to the oxidized cobalt mediator, which enables attainment of strikingly high photovoltages approaching 1 volt. Because the YD2-o-C8 porphyrin harvests sunlight across the visible spectrum, large photocurrents are generated. Cosensitization of YD2-o-C8 with another organic dye further enhances the performance of the device, leading to a measured power conversion efficiency of 12.3% under simulated air mass 1.5 global sunlight.