Synergetic Near- and Far-Field Plasmonic Effects for Optimal All-Perovskite Tandem Solar Cells with Maximized Infrared Absorption.

The efficiency and reliability of perovskite solar cells have rapidly increased in conjunction with the proposition of advanced single-junction and multi-junction designs that allow light harvesting to be maximized. However, Sn-based compositions required for optimized all-perovskite tandem devices have reduced absorption coefficients, as opposed to pure Pb perovskites. To overcome this, we investigate near- and far-field plasmonic effects to locally enhance the light absorption of infrared photons. Through optimization of the metal type, particle size, and volume concentration, we maximize effective light harvesting while minimizing parasitic absorption in all-perovskite tandem devices. Interestingly, incorporating 240 nm silver particles into the Pb-Sn perovskite layer with a volume concentration of 3.1% indicates an absolute power conversion efficiency enhancement of 2% in the tandem system. We present a promising avenue for experimentalists to realize ultrathin all-perovskite tandem devices with optimized charge carrier collection, diminishing the weight and the use of Pb.

Multifold Enhanced Photon Upconversion in a Composite Annihilator System Sensitized by Perovskite Nanocrystals.

Photon upconversion via triplet-triplet annihilation (TTA-UC) provides a pathway to overcoming the thermodynamic efficiency limits in single-junction solar cells by allowing the harvesting of sub-bandgap photons. Here, we use mixed halide perovskite nanocrystals (CsPbX3, X = Br/I) as triplet sensitizers, with excitation transfer to 9,10-diphenylanthracene (DPA) and/or 9,10-bis[(triisopropylsilyl)ethynyl]anthracene (TIPS-An) which act as the triplet annihilators. We observe that the upconversion efficiency is five times higher with the combination of both annihilators in a composite system compared to the sum of the individual single-acceptor systems. Our work illustrates the importance of using a composite system of annihilators to enhance TTA upconversion, demonstrated in a perovskite-sensitized system, with promise for a range of potential applications in light-harvesting, biomedical imaging, biosensing, therapeutics, and photocatalysis.

Composition Dictates Octahedral Tilt and Photostability in Halide Perovskites.

Halide perovskites are excellent candidate materials for use in solar cell, LED, and detector devices, in part because their composition can be tuned to achieve ideal optoelectronic properties. Empirical efficiency optimization has led the field toward compositions rich in FA (formamidinium) on the A-site and I on the X-site, with additional small amounts of MA (methylammonium) or Cs A-site cations and Br X-site anions. However, it is not clear how and why the specific compositions of alloyed, that is, mixed component, halide perovskites relate to photo-stability of the materials. Here, this work combines synchrotron grazing incidence wide-angle X-ray scattering, photoluminescence, high-resolution scanning electron diffraction measurements and theoretical modelling to reveal the links between material structure and photostability. Namely, this work finds that increased octahedral titling leads to improved photo-stability that is correlated with lower densities of performance-harming hexagonal polytype impurities. These results uncover the structural signatures underpinning photo-stability and can therefore be used to make targeted changes to halide perovskites, bettering the commercial prospects of technologies based on these materials.

Quantum barriers engineering toward radiative and stable perovskite photovoltaic devices.

Efficient photovoltaic devices must be efficient light emitters to reach the thermodynamic efficiency limit. Here, we present a promising prospect of perovskite photovoltaics as bright emitters by harnessing the significant benefits of photon recycling, which can be practically achieved by suppressing interfacial quenching. We have achieved radiative and stable perovskite photovoltaic devices by the design of a multiple quantum well structure with long (∼3 nm) organic spacers with oleylammonium molecules at perovskite top interfaces. Our L-site exchange process (L: barrier molecule cation) enables the formation of stable interfacial structures with moderate conductivity despite the thick barriers. Compared to popular short (∼1 nm) Ls, our approach results in enhanced radiation efficiency through the recursive process of photon recycling. This leads to the realization of radiative perovskite photovoltaics with both high photovoltaic efficiency (in-lab 26.0%, certified to 25.2%) and electroluminescence quantum efficiency (19.7 % at peak, 17.8% at 1-sun equivalent condition). Furthermore, the stable crystallinity of oleylammonium-based quantum wells enables our devices to maintain high efficiencies for over 1000 h of operation and >2 years of storage.

Strong angular and spectral narrowing of electroluminescence in an integrated Tamm-plasmon-driven halide perovskite LED.

Next-generation light-emitting applications such as displays and optical communications require judicious control over emitted light, including intensity and angular dispersion. To date, this remains a challenge as conventional methods require cumbersome optics. Here, we report highly directional and enhanced electroluminescence from a solution-processed quasi-2-dimensional halide perovskite light-emitting diode by building a device architecture to exploit hybrid plasmonic-photonic Tamm plasmon modes. By exploiting the processing and bandgap tunability of the halide perovskite device layers, we construct the device stack to optimise both optical and charge-injection properties, leading to narrow forward electroluminescence with an angular full-width half-maximum of 36.6° compared with the conventional isotropic control device of 143.9°, and narrow electroluminescence spectral full-width half-maximum of 12.1 nm. The device design is versatile and tunable to work with emission lines covering the visible spectrum with desired directionality, thus providing a promising route to modular, inexpensive, and directional operating light-emitting devices.

Miomectomía laparascópica de puerto único (LESS) utilizando puerto SILS: experiencia inicial en Latinoamérica / Single port laparoscopic myomectomy (LESS) using SILS port: initial experience in Latin America

Los miomas son la neoplasia benigna más común de la mujer. Su tratamiento puede ser variado aunque generalmente es quirúrgico. La miomectomía permite conservar el útero conservando a su vez la fertilidad. Kurt Semm introdujo a finales de los 70`s la vía laparoscópica como una opción para realización de miomectomía y desde entonces ha demostrado ser una opción segura y con buenos resultados clínicos y terapéuticos. En 2008, Dr. Y.W. Kim inicia con las técnicas laparoscópicas de un solo puerto (LESS) haciendo que la cirugía laparoscópica sea cada vez menos invasiva...

Contaminantes en los cuerpos de agua del sur de Sonora / Population, environment and health: pollution in water bodies in the south of Sonora

Objetivo. Ahondar en el conocimiento sobre la incidencia de las actividades productivas del hombre en su medio, y el riesgo potencial que representa el deterioro ambiental para su propia salud y la sobrevivencia de especies animales. Material y métodos. Se utilizó el paquete informático Decision Support System for Industrial Pollution Control DSS (IPC), desarrollado por el Banco Mundial, la Organización Panamericana de la Salud (OPS) y la Organización Mundial de la Salud (OMS), que se aplicó a un estudio de caso sobre los cuerpos de agua del sur de Sonora, durante 1996. Resultados. Estos sugieren que existen al menos tres factores que han contribuido a la desaparición de criaderos naturales de pescado y camarón en el municipio de Huatabampo: a) la filtración de fertilizantes y pesticidas en las aguas de los drenes; b) el asolvamiento producido por el depósito continuo, en el pasado, de agua de cola de la industria, c) y la descarga inapropiada de aguas negras en los drenes. El texto completo en inglés de este artículo está disponible en: http://www.insp.mx/salud/index.html

Seguimiento serológico de infección por Trypanosoma cruzi en individuos estudiados de 50 municipios del Estado de Jalisco, México de 1987 a 1994 / Serological follow-up of Trypanosoma cruzi infection from 1987 to 1994 in 50 counties of the State of Jalisco, Mexico

La Universidad de Guadalajara decidio realizar en 1987 un estudio seroepidemiologico para conocer la prevalencia de la infeccion por Trypanosoma cruzi en los 124 municipios del Estado de Jalisco, Mexico, en el cual se obtuvieron tasas de 21,6 por 100 habitantes. De diciembre de 1993 a junio de 1994 se realizo un seguimiento de algunos de esos individuos, estudiandose sólo 2669 de ellos, de 50 municipios de ßreas rurales del estado. Las causas de no encuesta de los faltantes fueron diversas, estando entre las mas importantes la emigracion (27,6 )y la renuencia (14,8). Encontramos a 476 positives (17,8 por cento) y 2193 negatives (82,2 por cento). Este segundo estudio nos permitio detectar 80 infectados nuevos (2,9 por cento) lo que representa una tasa de incidencia de 30 por 1000 habitantes. Sin embargo, encontramos una seroconversion en los individuos estudiados, ya que de 1007 individuos que estaban positivos en 1987, 943 de ellos continuan asi, mientras, que 64 individuos se negativizaron (2,3 por cento), no siendo esto imputable a fallas de laboratorio, la prevalencia de positividad detectada en ambos estudios fue casi identica 18, 1 y 17,8 por cento respectivamente, por lo que nosotros pensamos que las condiciones en que viven los individuos de las localidades rurales del Estado de Jalisco favorecen a que las infecciones continuen