Water resistant CsPbX₃ nanocrystals coated with polyhedral oligomeric silsesquioxane and their use as solid state luminophores in all-perovskite white light-emitting devices

We present an approach towards stable solid-state perovskite based luminophores with different emission colors via surface protection of CsPbX₃ (X = Br or I) with a polyhedral oligomeric silsesquioxane (POSS). This treatment results in water resistant perovskite nanocrystal powders, and prevents otherwise easy anion exchange between perovskite nanocrystals of different compositions mixed together in the solid state, which allows us to preserve their distinct emission spectra. We subsequently used mixtures of green-emitting POSS-CsPbBr₃ and red-emitting POSS-CsPb(Br/I)₃ nanocrystal powders to fabricate single layer all-perovskite down conversion white light-emitting devices.