Light Absorption Coefficient of CsPbBr₃ Perovskite Nanocrystals

Abstract

Inductively coupled plasma mass spectrometry (ICP-MS) was combined with UV-vis absorption spectroscopy and transmission electron microscopy to determine the size, composition, and intrinsic absorption coefficient μ_i of 4 to 11 nm sized colloidal CsPbBr₃ nanocrystals (NCs). The ICP-MS measurements demonstrate the nonstoichiometric nature of the NCs, with a systematic excess of lead for all samples studied. Rutherford backscattering measurements indicate that this enrichment in lead concurs with a relative increase in the bromide content. At high photon energies, μ_i is independent of the nanocrystal size. This allows the nanocrystal concentration in CsPbBr₃ nanocolloids to be readily obtained by a combination of absorption spectroscopy and the CsPbBr₃ sizing curve.