cm9b02944_si_001.pdf (508.79 kB)
Green-Emitting Powders of Zero-Dimensional Cs4PbBr6: Delineating the Intricacies of the Synthesis and the Origin of Photoluminescence
journal contribution
posted on 2019-09-16, 12:33 authored by Aniruddha Ray, Daniela Maggioni, Dmitry Baranov, Zhiya Dang, Mirko Prato, Quinten A. Akkerman, Luca Goldoni, Enrico Caneva, Liberato Manna, Ahmed L. AbdelhadyA detailed investigation
into the synthesis of green-emitting powders of Cs4PbBr6 and CsPbBr3 materials by antisolvent precipitation
from CsBr–PbBr2 precursor solutions in dimethylformamide
(DMF) and dimethyl sulfoxide (DMSO) is reported. Various solvated
lead bromide and polybromide species (PbBr2, [PbBr3]−, [PbBr4]2–, and possibly [PbBr5]3– or [PbBr6]4–) are detected in the precursor solutions
by optical absorbance and emission spectroscopies. The solvodynamic
size of the species in solution is strongly solvent-dependent: ∼1
nm species were detected in DMSO, while significantly larger species
were observed in DMF by dynamic light scattering. The solvodynamic
size of the lead bromide species plays a critical role in determining
the Cs-Pb-Br composition of the precipitated powders: smaller species
favor the precipitation of Cs4PbBr6, while larger
species template the formation of CsPbBr3 under identical
experimental conditions. The powders have been characterized by 133Cs and 207Pb solid-state nuclear magnetic resonance,
and 133Cs sensitivity toward the different Cs environments
within Cs4PbBr6 is demonstrated. Finally, the
possible origins of green emission in Cs4PbBr6 samples are discussed. It is proposed that a two-dimensional Cs2PbBr4 inclusion may be responsible for green emission
at ∼520 nm in addition to the widely acknowledged CsPbBr3 impurity, although we found no conclusive experimental evidence
supporting such claims.