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Degradation mechanisms in mixed-cation and mixed-halide CsFAPb(BrI) perovskite films under ambient conditions
Multicomponent perovskites of the type Cs x FA 1− x Pb(Br y I 1− y ) 3 are good candidates for highly efficient perovskite and tandem solar cells. In this work the degradation mechanisms of these multicomponent films were investigated and our results show that the degradation is a complex process, w...
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Published in: | Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2020-05, Vol.8 (18), p.932-9312 |
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Main Authors: | , , , , , , , , , , |
Format: | Article |
Language: | English |
Online Access: | Get full text |
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Summary: | Multicomponent perovskites of the type Cs
x
FA
1−
x
Pb(Br
y
I
1−
y
)
3
are good candidates for highly efficient perovskite and tandem solar cells. In this work the degradation mechanisms of these multicomponent films were investigated and our results show that the degradation is a complex process, with the formation of a number of intermediates and lead-based products.
In situ
X-ray diffraction analysis carried out in the first stages of the degradation indicate that different from MAPbI
3
perovskites, the degradation of these multicomponent films begins with the formation of hexagonal polytypes as intermediates, which in turn are converted to hydrated phases. The initial steps of the degradation were also monitored for the first time by
in situ
environmental scanning electron microscopy (ESEM) with 75% of relative humidity.
In situ
ESEM images show that the degradation has its beginning at the "valleys" of the wrinkled morphology found in these films, possibly because of a smaller grain size in these regions. XPS analysis confirms that the hydrated perovskite films continue to react with the environment, leading to the formation of metal hydroxides, carbonates, and oxides as final products. Our results also indicate that the degradation mechanism is highly dependent on the Cs concentration and Br content providing guidance for choosing the best compositions for efficient, but more environmentally stable solar cells.
With
in situ
ESEM and GIWAXS we saw that the perovskite degradation passes through hexagonal polytypes and is dependent on the composition. |
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ISSN: | 2050-7488 2050-7496 |
DOI: | 10.1039/d0ta01201g |