Exploring the cation dynamics in lead-bromide hybrid perovskites
Citation:
Motta C, El-Mellouhi F, Sanvito S, Exploring the cation dynamics in lead-bromide hybrid perovskites, Physical Review B - Condensed Matter and Materials Physics, 93, 23, 2016, 235412 -Download Item:
PhysRevB.93.235412.pdf (PDF) 608.7Kb
Abstract:
Density functional theory including a many-body treatment of dispersive forces is used to describe the
interplay between structure and electronic properties of two prototypical Br-based hybrid perovskites, namely,
CH
3
NH
3
PbBr
3
and HC(NH
2
)
2
PbBr
3
. We find that, like for some of their iodine-based counterparts, the molecules’
orientation plays a crucial role in determining the shape of both the conduction and valence bands around the
band edges. This is mostly evident in the case of CH
3
NH
3
PbBr
3
, which is a direct band-gap semiconductor when
the CH
3
NH
3
group is oriented along the (111) direction but turns indirect when the orientation is (100). We
have constructed a simple dipole model, with parameters all evaluated from
ab initio
calculations, to describe
the molecules’ depolarization dynamics. We find that, once the molecules are initially orientated along a given
high-symmetry direction, their room-temperature depolarization depends on the specific material investigated.
In particular we find that the ratio between the polarization decay constant of CH
3
NH
3
PbBr
3
and that of
HC(NH
2
)
2
PbBr
3
is about 2 at room temperature. With these results at hand we suggest a simple luminescence
decay experiment to prove our findings and establish a correlation between optical activity and the molecules’
dynamics in these materials.
Author's Homepage:
http://people.tcd.ie/sanvitos
Author: SANVITO, STEFANO
Type of material:
Journal ArticleCollections:
Series/Report no:
Physical Review B - Condensed Matter and Materials Physics93
23
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Full text availableKeywords:
prototypical Br-based hybrid perovskitesDOI:
http://dx.doi.org/10.1103/PhysRevB.93.235412Licences: