Lead halide perovskites have attracted considerable attention in the context of optoelectronic applications. Nanocrystals (NCs) of CsPbX3 (X = Cl, Br, I) exhibit bright photoluminescence, with emission tunable over the entire visible spectral region. However, previous studies on CsPbX3 NCs did not address key aspects such as surface chemistry and quantitative light absorption. Here[1] we elaborate on the synthesis of CsPbBr3 NCs and their surface chemistry. In addition, the intrinsic absorption coefficient was determined experimentally via ICP-MS measurements, combined with optical absorption measurements. 1H solution NMR was used to characterize sample purity, to elucidate the surface chemistry and to evaluate the influence of purification methods on the surface composition. We find that ligand binding to the NC surface is highly dynamic, and therefore, ligands are easily lost during the isolation and purification procedures. However, when a small amount of both oleic acid and oleylamine are added, the NCs can be purified, maintaining optical, colloidal and material integrity. In addition, we find that a high amine content in the ligand shell increases the quantum yield due to the improved binding of the carboxylic acid. This work sheds thus more light on the surface chemistry of CsPbBr3 NCs and opens the way for further surface modifications, required for the optoelectronic applications of these NCs.

Highly dynamic ligand binding and light absorption coefficient of cesium lead bromide perovskite nanocrystals

255th National Meeting (2018)

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