2, École Polytechnique Fédérale de Lausanne, Lausanne, , Switzerland
Fully inorganic cesium lead halide (CsPbX3, X = I, Br, or Cl) perovskite nanocrystals (PNCs) are a novel optoelectronic material with outstanding optical properties. In order to be successfully employed in solid-state optoelectronic devices, the process of carrier propagation in PNC solids must be understood. In the present work we fabricated controlled 2D assemblies of PNCs, allowing for the direct measurement of exciton diffusion by steady state and time-resolved photoluminescence (PL) microscopy. The results of each technique demonstrate a long-range FRET-mediated diffusion process characterized by a 200 nm exciton diffusion length and diffusivity as high as 0.5 cm2/s. These findings are comparable or greater than those measured in bulk inorganic perovskite and hybrid polycrystalline perovskites, exceeding reported values for chalcogen-based QDs solids by orders of magnitude.