Oxygen-Mediated (0D) Cs4PbX6 Formation during Open-Air Thermal Processing Improves Inorganic Perovskite Solar Cell Performance.

The desire to commercialize perovskite solar cells continues to mount, motivating the development of scalable production. Evaluations of the impact of open-air processing have revealed a variety of physical changes in the fabricated devices─with few changes having the capacity to be functionalized. Here, we highlight the beneficial role of ambient oxygen during the open-air thermal processing of metastable γ-CsPbI3-based perovskite thin films and devices. Physiochemical-sensitive probes elucidate oxygen intercalation and the formation of Pb-O bonds in the CsPbI3 crystal, entering via iodine vacancies at the surface, creating superoxide (O2-) through electron transfer reactions with molecular oxygen, which drives the formation of a zero-dimensional Cs4PbI6 capping layer during annealing (>330 °C). The chemical conversion permanently alters the film structure, helping to shield the subsurface perovskite from moisture and introduces lattice anchoring sites, stabilizing otherwise unstable γ-CsPbI3 films. This functional modification is demonstrated in γ-CsPbI2Br perovskite solar cells, boosting the operational stability and photoconversion efficiency of champion devices from 12.7 to 15.4% when annealed in dry air. Such findings prompt a reconsideration of glovebox-based perovskite solar cell research and establish a scenario where device fabrication can in fact greatly benefit from ambient oxygen.

Optical Properties of 2D Micro- and Nanostructures of ZnO:K.

ZnO nano- and microstructures doped with K were grown by the Vapor-Solid method. Wires and needles are the main morphology observed, although some structures in the form of ribbons and triangular plates were also obtained. Besides these, ball-shaped structures which grow around a central wire were also detected. Raman and cathodoluminescence investigations suggest that variations in morphology, crystalline quality and luminescence emissions are related to the different lattice positions that K occupies depending on its concentration in the structures. When the amount is low, K ions mainly incorporate as interstitials (Ki), whereas K occupies substitutional positions of Zn (KZn) when the amount of K is increased. Electron Backscattered Diffraction shows that ribbons and triangular plates are oriented in the (0001) direction, which indicates that the growth of this type of morphologies is related to distortions introduced by the Ki since this position favors the growth in the (0001) plane. In the case of the ball-shaped structures, the compositional analysis and Raman spectra show that they consist of K2SO4. Finally, the capability of the elongated structures to act as waveguides and optical resonators was investigated. Due to the size of the K ion, practically double that of the Zn, and the different positions it can adopt within the ZnO lattice (Ki or KZn), high distortions are introduced that compromise the resonators performance. Despite this, quality factor (Q) and fineness (F) show acceptable values (80 and 10 at 544 nm, respectively), although smaller than those reported for doping with smaller size alkali, such as Li.

Femtosecond laser induced thermophoretic writing of waveguides in silicate glass.

Here in, the fs-laser induced thermophoretic writing of microstructures in ad-hoc compositionally designed silicate glasses and their application as infrared optical waveguides is reported. The glass modification mechanism mimics the elemental thermal diffusion occurring in basaltic liquids at the Earth's mantle, but in a much shorter time scale (108 times faster) and over a well-defined micrometric volume. The precise addition of BaO, Na2O and K2O to the silicate glass enables the creation of positive refractive index contrast upon fs-laser irradiation. The influence of the focal volume and the induced temperature gradient is thoroughly analyzed, leading to a variety of structures with refractive index contrasts as high as 2.5 × 10-2. Two independent methods, namely near field measurements and electronic polarizability analysis, confirm the magnitude of the refractive index on the modified regions. Additionally, the functionality of the microstructures as waveguides is further optimized by lowering their propagation losses, enabling their implementation in a wide range of photonic devices.

Preferential Growth of ZnO Micro- and Nanostructure Assemblies on Fs-Laser-Induced Periodic Structures.

In this work, we demonstrate the use of laser-induced periodic surface structures (LIPSS) as templates for the selective growth of ordered micro- and nanostructures of ZnO. Different types of LIPSS were first produced in Si-(100) substrates including ablative low-frequency spatial (LSF) LIPSS, amorphous-crystalline (a-c) LIPSS, and black silicon structures. These laser-structured substrates were subsequently used for depositing ZnO using the vapor-solid (VS) method in order to analyze the formation of organized ZnO structures. We used scanning electron microscopy and micro-Raman spectroscopy to assess the morphological and structural characteristics of the ZnO micro/nano-assemblies obtained and to identify the characteristics of the laser-structured substrates inducing the preferential deposition of ZnO. The formation of aligned assemblies of micro- and nanocrystals of ZnO was successfully achieved on LSF-LIPSS and a-c LIPSS. These results point toward a feasible route for generating well aligned assemblies of semiconductor micro- and nanostructures of good quality by the VS method on substrates, where the effect of lattice mismatch is reduced by laser-induced local disorder and likely by a small increase of surface roughness.

[Compliance of latent tuberculosis infection treatment in a cohort of TB contacts]. / Cumplimiento del tratamiento de la infección tuberculosa latente en una cohorte de contactos de enfermos de tuberculosis.

OBJECTIVE: Compliance with the treatment of Latent Tuberculous Infection (ITL) is a determining factor in the control of tuberculosis. The objective of this study was to estimate the acceptance and compliance of the ITL treatment, and associated factors in contacts of patients with tuberculosis in Lleida. METHODS: Epidemiological analytical observational study, of a retrospective cohort follow-up, since the 1 January 2015 to 31 December 2016. The Participants were contacts of patients with tuberculosis in Lleida. Variables of the index case and independent and dependent variables (acceptance and compliance of the treatment) of contacts were studied through univariate and bivariate analysis. The strength of association was studied with odds ratio (OR) and confidence interval (IC) of 95% they were adjusted by a multivariate regression model. RESULTS: 69.1% of tuberculosis cases had a contact study, and 47.5% had at least one contact with prescription of preventive treatment. The treatment was accepted by 94.5% of contacts, and only 70.3% finalized this treatment. The completion was more frequent in patients who knew the meaning of latent tuberculosis infection treatment (ORa: 2.0; CI: 95% 1.0-4.1).

OBJETIVO: El cumplimiento del tratamiento de la Infección Tuberculosa Latente (ITL) es un factor determinante del control de la tuberculosis. El objetivo de este trabajo fue estimar la aceptación y el cumplimiento del tratamiento de la ITL y factores asociados en contactos de enfermos con tuberculosis en Lleida. METODOS: Estudio epidemiológico analítico observacional de seguimiento de una cohorte retrospectiva, desde el 1 de enero de 2015 al 31 de diciembre de 2016. Los participantes fueron los contactos de enfermos con tuberculosis de Lleida. Se estudiaron variables del caso índice y variables independientes y dependientes (aceptación y cumplimiento de la ITL) de los contactos, a través del análisis univariado y multivariado. La fuerza de asociación se estudió con el odds ratio (OR) y su intervalo de confianza (IC) del 95% y se ajustaron mediante modelos de regresión logística. RESULTADOS: El 69,1% de los casos de tuberculosis poseían estudio de contactos, y el 47,5% tenían algún contacto con prescripción de tratamiento preventivo. El 94,5% de los contactos aceptó el tratamiento de la ITL, y éste fue finalizado por el 70,3%. El cumplimiento fue más frecuente en los pacientes que conocían el significado del tratamiento de la ITL (ORa: 2,0; IC: 95% 1,0-4,1). CONCLUSIONES: En relación a la aceptación/cumplimiento del tratamiento de la ITL, destaca la influencia positiva de poseer conocimientos sobre la infección y su tratamiento. Los profesionales de Atención Primaria deberían proporcionar mayor educación sanitaria con el fin de mejorar el cumplimiento terapéutico de la ITL.