Near-Unity Photoluminescence Quantum Yield in CsPbBr₃ Nanocrystal Solid-State Films via Postsynthesis Treatment with Lead Bromide

Abstract

Metal halide perovskite nanocrystals (NCs)\n\t\t\t\t possess high photoluminescence (PL) quantum yield (PL)\n\t\t\t\t and color tunability. Yet, until now, it has been difficult to\n\t\t\t\t maintain the high PL observed in solution in spin-coated\n\t\t\t\t films. Here, we report a novel CsPbBr3 NCs room-temperature\n\t\t\t\t synthesis based on Cs acetate, which displays near-unity PL\n\t\t\t\t in solid-state films upon post-synthetic treatment with lead\n\t\t\t\t bromide. The as-synthesized NCs show a PL of 80% in spincoated\n\t\t\t\t films but the post-synthesis treatment further\n\t\t\t\t enhances the efficiency >95%. The high PL is further\n\t\t\t\t confirmed by the monomolecular decay of the PL (5.8 ns)\n\t\t\t\t indicating a nearly complete suppression of non-radiative\n\t\t\t\t channels. The obtained films demonstrate high stability in air\n\t\t\t\t and require around 3 weeks to decrease to half the initial PL value.