4 ) 3 (LATP) solid electrolyte is inexpensive, light, and highly ionically conductive but unstable against Li metal. To avoid the side reactions between LATP and Li metal, chemically inert and mechanically robust BN nanocoating was deposited onto LATP solid electrolyte as a stable interface to enable stable cycling in Li-metal batteries. This strategy can be applied to various unstable solid electrolytes and extend lifetime of solid-state Li-metal batteries with high energy density.

Two dimensional (2D) transition-metal dichalcogenide (TMD) based semiconductors have generated intense recent interest due to their novel optical and electronic properties, and potential for applications. In this work, we characterize the atomic and electronic nature of intrinsic point defects found in single crystals of these materials synthesized by two different methods-chemical vapor transport and self-flux growth. Using a combination of scanning tunneling microscopy (STM) and scanning transmission electron microscopy (STEM), we show that the two major intrinsic defects in these materials are metal vacancies and chalcogen antisites. We show that by control of the synthetic conditions, we can reduce the defect concentration from above 10 13 /cm 2 to below 10 11 /cm 2. Because these point defects act as centers for non-radiative recombination of excitons, this improvement in material quality leads to a hundred-fold increase in the radiative recombination efficiency.

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