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Platinum( ii ) binuclear complexes containing two platinum centers bridged by different types of ligands have received great research attention for their unique properties and potential applications in a variety of areas. The properties of these binuclear Pt( ii ) complexes, which could be significantly different from those of their mononuclear counterparts, are highly tunable by modifying their cyclometallating ligands and bridging ligands, as well as their structural configurations. The photophysical properties of these complexes involving a wide range of spectroscopic phenomena make them a very interesting class of materials to be spectroscopically studied. Applications of platinum( ii ) binuclear complexes have been explored in several areas, ranging from light emitting diodes, to sensors and photocatalysis. In this review, the molecular structures, photophysical properties, and applications of a variety of platinum( ii ) binuclear complexes are discussed. We intend to shed some light on the recent progress in this field and give a future outlook. 

Optically pumped white light-emitting diodes (WLEDs), consisting of blue/ultraviolet LED chips and down conversion phosphors, have a wide range of applications in our daily life, such as full color display and solid-state lighting. While remarkable progress in light quality, device efficiency, and lifetime has been achieved during the last two decades, many challenges remain in optically pumped WLEDs, and searching for low cost high performance down conversion phosphors is still of great interest. Recently, metal halide perovskites have emerged as a highly promising new generation of light emitters for their exceptional optical properties with high quantum efficiencies and color tunability, which have also inspired researchers to investigate their derivatives. In this perspective, we briefly review the progress during the last few years in the development of metal halide perovskites and perovskite-related materials as down conversion phosphors for optically pumped WLEDs. We also highlight some major issues and challenges that need to be addressed to enable perovskite-based light emitters to possibly replace currently used rare-earth doped inorganic phosphors and quantum dots. 

Metal halide perovskite nanocrystals (NCs) have emerged as new-generation light-emitting materials with narrow emissions and high photoluminescence quantum efficiencies (PLQEs). Various types of perovskite NCs, e.g., platelets, wires, and cubes, have been discovered to exhibit tunable emissions across the whole visible spectrum. Despite remarkable advances in the field of perovskite NCs, many nanostructures in inorganic NCs have not yet been realized in metal halide perovskites, and producing highly efficient blue-emitting perovskite NCs remains challenging and of great interest. Here, we report the discovery of highly efficient blue-emitting cesium lead bromide (CsPbBr 3 ) perovskite hollow NCs. By facile solution processing of CsPbBr 3 precursor solution containing ethylenediammonium bromide and sodium bromide, in situ formation of hollow CsPbBr 3 NCs with controlled particle and pore sizes is realized. Synthetic control of hollow nanostructures with quantum confinement effect results in color tuning of CsPbBr 3 NCs from green to blue, with high PLQEs of up to 81%.