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[초청강연]Ultralight, efficient, and stable perovskite light emitting diodes
Metal halide perovskites (MHPs) have been considered next-generation light-emitting materials due to their excellent emission property of narrowband emission. Still, even after various material types of perovskites including 3D, low-dimensional quasi-2D, and colloidal nanocrystal structures were studied, perovskite light-emitting diodes (PeLEDs) have not realized high luminance, high efficiency, and long lifetime simultaneously, because of the intrinsic limitations related to the trade-off properties between charge transport and confinement in each type of perovskite materials. Here, we report an ultra-bright, efficient, and stable PeLEDs made of core/shell perovskite nanocrystals with a size of ~10 nm obtained using a simple in situ reaction of benzylphosphonic acid (BPA) additive with 3D polycrystalline perovskite films without separate synthesis process. During the reaction, large 3D crystals are split into nanocrystals and the BPA surrounds the nanocrystals, achieving strong carrier confinement while maintaining good charge-transport properties of 3D perovskites. We demonstrate simultaneously efficient, bright, and stable PeLEDs that have maximum brightness of ~470,000 cd m-2, maximum external quantum efficiency of 28.9% (maximum current efficiency of 151 cd A-1), and half-lifetime of 520 h at 1,000 cd m-2 (estimated half-lifetime >30,000 h at 100 cd m-2). These results suggest that PeLEDs are not only laboratory-level high-efficiency devices, but also promising candidates for commercial self-emissive displays and lighting applications.
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