Superfluorescence from Binary Perovskite

Lead-halide perovskite APbX3 (A=Cs or organic cation; X=Cl, Br, I) quantum dots (QDs) are subject of intense research due to their exceptional properties as both classical 1 and quantum light sources. Here we present perovskite-type (ABO3) binary nanocrystal superlattices, created via the shape-directed co-assembly of steric-stabilized, highly luminescent cubic CsPbBr 3 nanocrystals (which occupy the B and/or O lattice sites), assembled in combination with spherical Fe 3O4 or NaGdF4 nanocrystals (A sites). These ABO3 superlattices, as well as the binary NaCl and AlB 2 superlattice structures that we demonstrated, exhibit a high degree of orientational ordering of the CsPbBr 3 nanocubes which preserve their high oscillator strength and long exciton coherence time in the assembly. Such superlattices exhibit superfluorescence—a collective emission that results in a burst of photons with ultrafast radiative decay (22 picoseconds) that could be tailored, by structural engineering of the nanoparticle assembly, for use in ultrabright (quantum) light sources. Our work paves the way for further exploration of complex, ordered and functionally useful perovskite mesostructures.