1,721,335 research outputs found
Energy Spotlight
No full textFour articles recently published in ACS Energy Letters are featured in this Energy Spotlight. These highlights include bright light-emitting diodes based on FAPbBr3 perovskite nanocrystals, an ACS Editors Choice Article of this month (highlighted by Tae-Woo Lee); reversible p-doping of CsPbBr3 nanocrystals via electrochemical hole injection (highlighted by Csaba Janáky); and managing surface defects to improve the perovskite solar cell performance (highlighted by Filippo De Angelis). These and other articles included in this issue provide exciting new advances in energy conversion and storage processes.N
Protestation des apostolischen Nuntius in der Schweiz gegen das Dekret des katholischen Grossen Raths des Kantons St. Gallen vom 28. Okt. 1833, die Bisthumsangelegenheiten betreffend
No full text[Filippo de Angelis]Genaue Datierung: "Luzern, den 22. November 1833. Der apostolische Nuntius bei der schweizerischen Eidgenossenschaft, Ph., Erzbischof von Carthago.
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)
Stark effect in perovskite/TiO2 solar cells: Evidence of local interfacial order
No full textTo unveil the mechanisms controlling photovoltaic conversion in high-performing perovskite-based mesostructured solar cells, we focus on the key role played by the mesoporous oxide/perovskite interface. We employ several spectroscopic techniques to design a complete scenario and corroborate our results with first principle density functional theory calculations. In particular Stark spectroscopy, a powerful tool allowing interface-sensitive analysis is employed to prove the existence of oriented permanent dipoles, consistent with the hypothesis of an ordered perovskite layer, close to the oxide surface. The existence of a structural order, promoted by specific local interactions, could be one of the decisive reasons for highly efficient carriers transport within perovskite films. © 2014 American Chemical Society
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
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
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
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
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