Hybrid halide perovskites represent one of the most promising solutions toward the fabrication of all solid nanostructured solar cells, with improved efficiency and long-term stability. This article aims at investigating the structural properties of iodide/chloride mixed-halide perovskites and correlating them with their photovoltaic performances. We found out that, independent of the components ratio in the precursor solution, Cl incorporation in an iodide-based structure, is possible only at relatively low concentration levels (below 3–4%). However, even if the material band gap remains substantially unchanged, the Cl doping dramatically improves the charge transport within the perovskite layer, explaining the outstanding performances of meso-superstructured solar cells based on this material.

Hybrid halide perovskites represent one of the most promising solutions toward the fabrication of all solid nanostructured solar cells with improved efficiency and long-term stability. This article aims at investigating the structural properties of the iodide/chloride mixed-halide perovskites and correlating them with the photovoltaic performances of the related sensitized solar cells. We found out that, independently on the components ratio in the precursor solution, Cl incorporation, in a I-based structure, is possible only at relatively low concentration levels (below 3-4%). However, even if the material band-gap remains substantially unchanged, incorporation of Cl as a dopant dramatically improves the charge transport within the perovskite layer, explaining the outstanding performances of meso-superstructured solar cells based on this material.

The influence of thermal treatments on the properties of mixed bromide-iodide organolead perovskites (MAPbI3−xBrx, MA=CH3NH3) is investigated in films prepared in air by single-step solution processes based on different precursor solutions. Initially, the bandgap energy (EG) dependence on composition is reconsidered on films obtained by mixtures of tri-halide solutions.An EG(x) relation is obtained that is expected to be independent of the film properties and can be used to assess perovskite composition. In these samples recombination centres are observed whose energy depth increases with x, likely involving the simultaneous presence of iodide and bromide, while the Urbach energy increases with the grain surface-to-volume ratio, which points out that the defects giving sub-bandgap absorption originate from grain boundaries. Tri-halide mixtures allow perovskite synthetic processes suitable for solar cell production, being fast and reproducible. A slight MABr excess in the solution made of MABr and PbI2 gives MAPbI2Br films free of PbI2 phases and with a high compositional stability, but non-radiative recombination channels can make the material not appropriate for high efficiency solar cells.Finally, the solution made of MAI and PbBr2 (3:1 molar ratio) is the less promising for solar cell production because its non-stoichiometric nature synthesis reproducibility an issue.

Despite advances in our knowledge of celiac disease, the most current and authoritative recommendations conclude that diagnosis requires at least four biopsy specimens to be taken from the duodenal area. These recommendations are based on the perception that classic endoscopic markers are not adequate to target biopsy sampling to sites of villous damage in the duodenum. In the past few years, newly developed procedures and technologies have improved endoscopic recognition of the duodenum. These advances make possible the real-time recognition of the duodenal villous pattern during an upper endoscopy procedure, and thereby have the potential to optimize diagnostic accuracy. It is, therefore, reasonable to hypothesize that upper endoscopy might have a more incisive role in the diagnosis of celiac disease than merely providing a means of obtaining biopsy specimens for histological analysis. This Review highlights the new technologies in the field of upper endoscopy that could be helpful for the diagnosis of celiac disease, including the water-immersion technique, chromoendoscopy, high-resolution magnification endoscopy, optimal band imaging, optical coherence tomography and confocal endomicroscopy.

The results add support to the recommendation that EUS staging of pancreatic head neoplasms should be performed prior to stent placement.