TY - JOUR
T1 - Cooling-Induced Order-Disorder Phase Transition in CsPbBr3 Nanocrystal Superlattices
AU - Filippi, Umberto
AU - Toso, Stefano
AU - Zaffalon, Matteo L.
AU - Pianetti, Andrea
AU - Li, Zhanzhao
AU - Marras, Sergio
AU - Goldoni, Luca
AU - Meinardi, Francesco
AU - Brovelli, Sergio
AU - Baranov, Dmitry
AU - Manna, Liberato
N1 - © 2024 The Author(s). Advanced Materials published by Wiley‐VCH GmbH.
PY - 2024/11/20
Y1 - 2024/11/20
N2 - Perovskite nanocrystal superlattices are being actively studied after
reports have emerged on collective excitonic properties at cryogenic
temperatures, where energetic disorder is minimized due to the frozen
lattice vibrations. However, an important issue related to structural
disorder of superlattices at low temperatures has received little
attention to date. In this work, it is shown that CsPbBr3
nanocrystal superlattices undergo a reversible order–disorder transition
upon cooling to 90 K. The transition consists of the loss of structural
coherence, that is, increased nanocrystal misalignment, and contraction
of the superlattices, as revealed by temperature-dependent X-ray
diffraction, and is ascribed to the solidification of ligands (on the
basis of Raman spectroscopy). Introducing shorter amines on the
nanocrystal surface allows to mitigate these changes, improve order, and
shorten interparticle distance. It is demonstrated that the low
temperature phase of the short ligand-capped nanocrystal superlattices
is characterized by a strong exciton migration observable in the
photoluminescence decay, which is due to the shrinkage of the
inter-nanocrystal distance.
AB - Perovskite nanocrystal superlattices are being actively studied after
reports have emerged on collective excitonic properties at cryogenic
temperatures, where energetic disorder is minimized due to the frozen
lattice vibrations. However, an important issue related to structural
disorder of superlattices at low temperatures has received little
attention to date. In this work, it is shown that CsPbBr3
nanocrystal superlattices undergo a reversible order–disorder transition
upon cooling to 90 K. The transition consists of the loss of structural
coherence, that is, increased nanocrystal misalignment, and contraction
of the superlattices, as revealed by temperature-dependent X-ray
diffraction, and is ascribed to the solidification of ligands (on the
basis of Raman spectroscopy). Introducing shorter amines on the
nanocrystal surface allows to mitigate these changes, improve order, and
shorten interparticle distance. It is demonstrated that the low
temperature phase of the short ligand-capped nanocrystal superlattices
is characterized by a strong exciton migration observable in the
photoluminescence decay, which is due to the shrinkage of the
inter-nanocrystal distance.
UR - https://doi.org/10.26434/chemrxiv-2024-5q319
U2 - 10.1002/adma.202410949
DO - 10.1002/adma.202410949
M3 - Article
C2 - 39568247
SN - 1521-4095
JO - Advanced Materials
JF - Advanced Materials
M1 - e2410949
ER -