Organic–inorganic lead halide perovskites have shown photovoltaic performances above 20% in a range of solar cell architectures while offering simple and low-cost processability. Despite the multiple ionic compositions that have been reported so far, the presence of organic constituents is an essential element in all of the high-efficiency formulations, with the methylammonium and formamidinium cations being the sole efficient options available to date. In this study, we demonstrate improved material stability after the incorporation of a large organic cation, guanidinium, into the MAPbI3 crystal structure, which delivers average power conversion efficiencies over 19%, and stabilized performance for 1,000 h under continuous light illumination, a fundamental step within the perovskite field.

Semitransparent efficient methylammonium lead iodide perovskite based solar cells.

The topographic features of an implant, which mechanically regulate cell behaviors and functions, are critical for the clinical success in tissue regeneration. How cells sense and respond to the topographical cues, e.g., interfacial roughness, is yet to be fully understood and even debatable. Here, the mechanotransduction and fate determination of human mesenchymal stem cells (MSCs) on surface roughness gradients are systematically studied. The broad range of topographical scales and high‐throughput imaging is achieved based on a catecholic polyglycerol coating fabricated by a one‐step‐tilted dip‐coating approach. It is revealed that the adhesion of MSCs is biphasically regulated by interfacial roughness. The cell mechanotransduction is investigated from focal adhesion to transcriptional activity, which explains that cellular response to interfacial roughness undergoes a direct force‐dependent mechanism. Moreover, the optimized roughness for promoting cell fate specification is explored.

Interfacial multivalent interactions at pathogen-cell interfaces can be competitively inhibited by multivalent scaffolds that prevent pathogen adhesion to the cells during the initial stages of infection. The lack of understanding of complex biological systems makes the design of an efficient multivalent inhibitor a toilsome task. Therefore, we have highlighted the main issues and concerns associated with blocking pathogen at interfaces, which are dependent on the nature and properties of both multivalent inhibitors and pathogens, such as viruses and bacteria. The challenges associated with different cores or carrier scaffolds of multivalent inhibitors are concisely discussed with selected examples.

Mixed monolayers of a water-soluble tetracationic porphyrin (TMPyP) and an insoluble lipid matrix with anionic head groups (DMPA) were formed by the cospreading method. A ratio TMPyP:DMPA ) 1:4 was selected by investigation of π-area isotherms and stability of the cospread monolayer. Reflection spectroscopy has been used to infer the molecular organization of the porphyrin molecules in the complex monolayer at the air-water interface. A blue shift in the Soret band was observed with increasing surface pressure. The mixed monolayer of TMPyP:DMPA ) 1:4 was transferred onto a glass substrate, and the molecular organization of the porphyrin was studied by transmission spectroscopy with plane polarized light (s and p) under various angles of incidence. The analysis of the reflection spectra at the air-water interface and absorption spectrum of the mixed monolayer on glass leads to a model of partial stacking of the porphyrin molecules in the monolayer at the air-water interface when the surface pressure is increased. On the glass substrate, the TMPyP molecules attached to DMPA are monomeric. Further, indirect evidence for the partial stacking model in the case of the mixture TMPyP:DMPA ) 1:4 was obtained from the investigation of the mixed monolayer TMPyP:DMPA:PME ) 1:4:16 (PME, methyl palmitate) at the air-water interface and transferred on glass. The presence of the neutral lipid molecules facilitates dense packing of the insoluble monolayer matrix and the matching of surface charge densities of the matrix and the porphyrin moiety. In this way, the intermolecular interactions between porphyrin molecules at the air-water interface under high surface pressure are reduced and the stacking is avoided.