1,721,113 research outputs found
Alignment of energy levels in dye/semiconductor interfaces by GW calculations: Effects due to coadsorption of solvent molecules
Full text linkThe performance of dye-sensitized solar cells is tightly linked to the relative energy level alignment of its constituents. In this paper the electronic properties of a model of dye-sensitized solar cell are studied by accurate first-principle calculations taking into account many-body effects beyond density-functional theory. The cell model includes one layer of co-adsorbed solvent (water or acetonitrile) molecules. Solvent molecules induce an upwards energy shift in the TiO2bands; such a shift is larger in the case of acetonitrile. The accurate determination of the energy levels allows the theoretical estimation of the maximum attainable open circuit voltage (Voc).This document is the Accepted Manuscript version of a Published Work that appeared in final form in PHYSICAL REVIEW B, copyright ©2014 American Physical Society after peer review and technical editing by the publisher.
http://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.15541
Relativistic GW calculations on CH3 NH3 PbI 3 and CH3 NH3 SnI3 Perovskites for Solar Cell Applications
Full text linkHybrid AMX 3 perovskites (A = Cs, CH 3 NH 3; M = Sn, Pb; X = halide) have revolutionized the scenario of emerging photovoltaic technologies, with very recent results demonstrating 15% efficient solar cells. The CH3 NH3 PbI3 /MAPb(I1-x Clx)3 perovskites have dominated the field, while the similar CH3 NH 3 SnI3 has not been exploited for photovoltaic applications. Replacement of Pb by Sn would facilitate the large uptake of perovskite-based photovoltaics. Despite the extremely fast progress, the materials electronic properties which are key to the photovoltaic performance are relatively little understood. Density Functional Theory electronic structure methods have so far delivered an unbalanced description of Pb- and Sn-based perovskites. Here we develop an effective GW method incorporating spin-orbit coupling which allows us to accurately model the electronic, optical and transport properties of CH3 NH3 SnI3 and CH3 NH3 PbI3, opening the way to new materials design. The different CH3 NH3 SnI3 and CH 3 NH3 PbI3 electronic properties are discussed in light of their exploitation for solar cells, and found to be dominantly due to relativistic effects. These effects stabilize the CH3 NH 3 PbI3 material towards oxidation, by inducing a deeper valence band edge. Relativistic effects, however, also increase the material band-gap compared to CH3 NH3 SnI3, due to the valence band energy downshift (∼0.7 eV) being only partly compensated by the conduction band downshift (∼0.2 eV)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Boron Functionalization and Unusual B-C Bond Activation in Rh(III) and Ir(III) Complexes with Diphenylbis(pyrazolylborate) Ligand (Ph2Bp)
No full textThe Rh(III) and Ir(III) pentamethylcyclopentadienyl compounds
[M(Cp*)(κ2-Ph2Bp)Cl] (M = Rh, 1; M = Ir, 4) were readily prepared from
interaction of the salt K[Ph2Bp] (Ph2Bp = diphenylbis(pyrazolyl)borate) and the
[M(Cp*)Cl2]2 dimer precursors in dichloromethane under anhydrous conditions.
When the same reactions were carried out in non-anhydrous conditions by using
acetonitrile as solvent, we observed, in the case of Rh, both B−N bond hydrolysis
and Rh−C(Ph) bond activation with the formation of the hydroxy(pyrazolyl)-
borate complex [Rh(Cp*)(Ph){κ2-(pz)(OH)BPh2}] (2). In contrast, in the case
of Ir only B−N hydrolysis was observed and the ionic species [Ir(Cp*)(Hpz){κ2-
(pz)(OH)BPh2}]Cl (5) was obtained, upon coordination of the liberated Hpz.
Additionally, by reaction of 1 with AgClO4 in acetonitrile, the ionic [Rh(Cp*)-
(Ph){κ2-(pz)(OH)B(OH)}]ClO4 (3) was isolated. Complexes 1−3 and 5 have
been structurally characterized by X-ray crystallography. Spectral studies have been
performed for all species, together with a computational DFT modeling investigation. A decomposition mechanism for the
diphenylbis(pyrazolyl)borate ligand in the different complexes is proposed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Data set for Chemical bond analysis for the entire periodic table: Energy Decomposition and Natural Orbitals for Chemical Valence in the Four-Component Relativistic Framework
No full textData related with the publication :Chemical bond analysis for the entire periodic table:
Energy Decomposition and Natural Orbitals for Chemical Valence in the Four-Component Relativistic Framework by Diego Sorbelli, Paola Belanzoni, Loriano Storchi, Olivia Bizzarri, Beatrice Bizzarri, Edoardo Mosconi and Leonardo Belpassi
Input and data for:
Tab.1 --> data in dir "w_dimer_AVDZ" and in dir "ADF/w_dimer".
Tab.2 --> data in dir "Agalkyne" and in dir "ADF/Agalkyne"
Tab.3 --> data in dir "TMC05ethene
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