Single crystals of methylammonium lead trihalide perovskites (MAPbX3; MA=CH3NH3+, X=Br− or I−) have shown remarkably low trap density and charge transport properties; however, growth of such high-quality semiconductors is a time-consuming process. Here we present a rapid crystal growth process to obtain MAPbX3 single crystals, an order of magnitude faster than previous reports. The process is based on our observation of the substantial decrease of MAPbX3 solubility, in certain solvents, at elevated temperatures. The crystals can be both size- and shape-controlled by manipulating the different crystallization parameters. Despite the rapidity of the method, the grown crystals exhibit transport properties and trap densities comparable to the highest quality MAPbX3 reported to date. The phenomenon of inverse or retrograde solubility and its correlated inverse temperature crystallization strategy present a major step forward for advancing the field on perovskite crystallization.

Two-dimensional layered MoS 2 nanosheets exhibit a wide range of attractive properties and hold great promise in myriad fields. However, the poor performance of surface functionality greatly limits their applications. In this paper, we report on a facile approach to direct synthesis of organic functional group decorated MoS 2 (OFGD-MoS 2 ) nanosheets based on the simultaneous exfoliation of bulk MoS 2 crystals and chemical conjugation of thiol ligands. The morphology and structure of OFGD-MoS 2 nanosheets are systematically characterized using microscopy (TEM, SEM, AFM), thermal gravimetric analysis (TGA), and spectroscopy (Raman, FTIR, XPS) measurements. The content of attached functional groups can be controlled simply by changing the experimental conditions. Furthermore, the introduced functional groups show excellent structural stability and high chemical reactivity, making them promising for further modification as confirmed by the in situ growth of inorganic nanoparticles and polymers. In addition, surface functionalized WS 2 nanosheets can also be synthesized by this approach. This investigation paves the way for the synthesis and applications of advanced MoS 2 -based materials.

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The main obstacles that hinder the development of efficient lithium sulfur (Li-S) batteries are the polysulfide shuttling effect in sulfur cathode and the uncontrollable growth of dendritic Li in the anode. An all-purpose flexible electrode that can be used both in sulfur cathode and Li metal anode is reported, and its application in wearable and portable storage electronic devices is demonstrated. The flexible electrode consists of a bimetallic CoNi nanoparticle-embedded porous conductive scaffold with multiple Co/Ni-N active sites (CoNi@PNCFs). Both experimental and theoretical analysis show that, when used as the cathode, the CoNi and Co/Ni-N active sites implanted on the porous CoNi@PNCFs significantly promote chemical immobilization toward soluble lithium polysulfides and their rapid conversion into insoluble Li 2 S, and therefore effectively mitigates the polysulfide shuttling effect. Additionally, a 3D matrix constructed with porous carbonous skeleton and multiple active centers successfully induces homogenous Li growth, realizing a dendrite-free Li metal anode. A Li-S battery assembled with S/CoNi@PNCFs cathode and Li/CoNi@PNCFs anode exhibits a high reversible specific capacity of 785 mAh g −1 and long cycle performance at 5 C (capacity fading rate of 0.016% over 1500 cycles).

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