Dmitry Baranov
Associate senior lecturer
Aging of Self-Assembled Lead Halide Perovskite Nanocrystal Superlattices : Effects on Photoluminescence and Energy Transfer
Author
Summary, in English
Excitonic coupling, electronic coupling, and cooperative interactions in
self-assembled lead halide perovskite nanocrystals were reported to
give rise to a red-shifted collective emission peak with accelerated
dynamics. Here we report that similar spectroscopic features could
appear as a result of the nanocrystal reactivity within the
self-assembled superlattices. This is demonstrated by studying CsPbBr3
nanocrystal superlattices over time with room-temperature and cryogenic
micro-photoluminescence spectroscopy, X-ray diffraction, and electron
microscopy. It is shown that a gradual contraction of the superlattices
and subsequent coalescence of the nanocrystals occurs over several days
of keeping such structures under vacuum. As a result, a narrow,
low-energy emission peak is observed at 4 K with a concomitant
shortening of the photoluminescence lifetime due to the energy transfer
between nanocrystals. When exposed to air, self-assembled CsPbBr3 nanocrystals develop bulk-like CsPbBr3
particles on top of the superlattices. At 4 K, these particles produce a
distribution of narrow, low-energy emission peaks with short lifetimes
and excitation fluence-dependent, oscillatory decays. Overall, the aging
of CsPbBr3 nanocrystal assemblies dramatically alters their
emission properties and that should not be overlooked when studying
collective optoelectronic phenomena nor confused with superfluorescence
effects.
self-assembled lead halide perovskite nanocrystals were reported to
give rise to a red-shifted collective emission peak with accelerated
dynamics. Here we report that similar spectroscopic features could
appear as a result of the nanocrystal reactivity within the
self-assembled superlattices. This is demonstrated by studying CsPbBr3
nanocrystal superlattices over time with room-temperature and cryogenic
micro-photoluminescence spectroscopy, X-ray diffraction, and electron
microscopy. It is shown that a gradual contraction of the superlattices
and subsequent coalescence of the nanocrystals occurs over several days
of keeping such structures under vacuum. As a result, a narrow,
low-energy emission peak is observed at 4 K with a concomitant
shortening of the photoluminescence lifetime due to the energy transfer
between nanocrystals. When exposed to air, self-assembled CsPbBr3 nanocrystals develop bulk-like CsPbBr3
particles on top of the superlattices. At 4 K, these particles produce a
distribution of narrow, low-energy emission peaks with short lifetimes
and excitation fluence-dependent, oscillatory decays. Overall, the aging
of CsPbBr3 nanocrystal assemblies dramatically alters their
emission properties and that should not be overlooked when studying
collective optoelectronic phenomena nor confused with superfluorescence
effects.
Publishing year
2021-01-26
Language
English
Pages
650-664
Publication/Series
ACS Nano
Volume
15
Issue
1
Document type
Journal article
Publisher
The American Chemical Society (ACS)
Keywords
- energy transfer
- environmental stability
- low-temperature photoluminescence
- nanocrystal superlattices
- perovskite nanocrystals
- reactivity
- self-assembly
Status
Published
ISBN/ISSN/Other
- ISSN: 1936-0851