Growth of millimeter-sized 2D metal iodide crystals induced by ion-specific preference at water-air interfaces.

Conventional liquid-phase methods lack precise control in synthesizing and processing materials with macroscopic sizes and atomic thicknesses. Water interfaces are ubiquitous and unique in catalyzing many chemical reactions. However, investigations on two-dimensional (2D) materials related to water interfaces remain limited.

Excessive Iodine Enabled Ultrathin Inorganic Perovskite Growth at the Liquid-Air Interface.

The liquid-air interface offers a platform for the in-plane growth of free-standing materials. However, it is rarely used for inorganic perovskites and ultrathin non-layered perovskites. Herein the liquid-air interfacial synthesis of inorganic perovskite nanosheets (Cs Bi I , Cs Sb I ) is achieved simply by drop-casting the precursor solution with only the addition of iodine.

Thickness dependent properties of ultrathin perovskite nanosheets with Ruddlesden-Popper-like atomic stackings.

Ruddlesden-Popper perovskites possess a rich variety of multiple phases due to their mixed organic cations and variable layer numbers. However, the direct observation of these phases and their optical performance in ultrathin nanosheets, have rarely been reported. Here we demonstrate, through a one-pot CVD synthesis method to incorporate MA and NMA cations into PbI simultaneously, that the stackings of Ruddlesden-Popper phases with a distribution of a number of layers 〈〉 can be produced within a single perovskite nanosheet.

Engineering the Phases and Heterostructures of Ultrathin Hybrid Perovskite Nanosheets.

Low-dimensional perovskites have gained increasing attention recently, and engineering their material phases, structural patterning and interfacial properties is crucial for future perovskite-based applications. Here a phase and heterostructure engineering on ultrathin perovskites, through the reversible cation exchange of hybrid perovskites and efficient surface functionalization of low-dimensional materials, is demonstrated. Using PbI as precursor and template, perovskite nanosheets of varying thickness and hexagonal shape on diverse substrates is obtained.

Female Gender Remains a Significant Barrier to Access Cataract Surgery in South Asia: A Systematic Review and Meta-Analysis.

Purpose: To determine whether the female gender is a barrier for the access to cataract surgery services in South Asia in the last two decades.

Methods: Eligible cross-sectional studies were identified via computer searches and reviewing the reference lists of the obtained articles. The cataract surgical coverage (CSC) by sex based on person and eyes at visual acuity <3/60 and 6/18 is extracted.