Catálogo de publicaciones - revistas

<jats:p>Randomizing news stories reveals broad public impacts</jats:p>

<jats:p>With funding for museum collections in peril, new species await discovery and names that may never come</jats:p>

<jats:p>A pair of philosophers probe the ethical implications of designing social robots</jats:p>

<jats:p>Silicate perovskite-type phases are the most abundant constituent inside our planet and are the predominant minerals in Earth’s lower mantle more than 660 kilometers below the surface. Magnesium-rich perovskite is a major lower mantle phase and undergoes a phase transition to post-perovskite near the bottom of the mantle. Calcium-rich perovskite is proportionally minor but may host numerous trace elements that record chemical differentiation events. The properties of mantle perovskites are the key to understanding the dynamic evolution of Earth, as they strongly influence the transport properties of lower mantle rocks. Perovskites are expected to be an important constituent of rocky planets larger than Mars and thus play a major role in modulating the evolution of terrestrial planets throughout the universe.</jats:p>

<jats:p>The efficiencies of perovskite solar cells have gone from single digits to a certified 22.1% in a few years’ time. At this stage of their development, the key issues concern how to achieve further improvements in efficiency and long-term stability. We review recent developments in the quest to improve the current state of the art. Because photocurrents are near the theoretical maximum, our focus is on efforts to increase open-circuit voltage by means of improving charge-selective contacts and charge carrier lifetimes in perovskites via processes such as ion tailoring. The challenges associated with long-term perovskite solar cell device stability include the role of testing protocols, ionic movement affecting performance metrics over extended periods of time, and determination of the best ways to counteract degradation mechanisms.</jats:p>

<jats:p>Semiconducting lead halide perovskites (LHPs) have not only become prominent thin-film absorber materials in photovoltaics but have also proven to be disruptive in the field of colloidal semiconductor nanocrystals (NCs). The most important feature of LHP NCs is their so-called defect-tolerance—the apparently benign nature of structural defects, highly abundant in these compounds, with respect to optical and electronic properties. Here, we review the important differences that exist in the chemistry and physics of LHP NCs as compared with more conventional, tetrahedrally bonded, elemental, and binary semiconductor NCs (such as silicon, germanium, cadmium selenide, gallium arsenide, and indium phosphide). We survey the prospects of LHP NCs for optoelectronic applications such as in television displays, light-emitting devices, and solar cells, emphasizing the practical hurdles that remain to be overcome.</jats:p>