Improving Stability of Lead Halide Perovskite via PbF2 Layer Covering.
2020
The
stability of perovskites is an urgent problem to be solved
before commercialization. An ultrathin PbF2 layer covering
the perovskite can be an effective strategy to improve the stability
of the perovskite greatly. The perovskite/PbF2 interface
(XPbI3/PbF2, X = Cs and MA) is constructed,
and the structural and chemical properties are studied by first-principles
calculations. The results show that PbF2 has better structural
stability than the perovskites and can stabilize the octahedral frame
of perovskite in the perovskite/PbF2 interface. The PbF2 layer reconstructs the XPbI3 surface, resulting
in the perovskite PbI interface transforming into a more stable XI
interface in the perovskite/PbF2 interface. Meanwhile,
the tiny stress compression in the perovskite/PbF2 interface
can enhance the stability of perovskite. The large affinity of F atoms
can adsorb free Pb atoms and suppress deleterious ion migration. In
addition, the XPbI3/PbF2 interfaces have good
dynamic stability at room temperature (300 K). Therefore, the PbF2 layer covering provides new ideas for the stability study
of perovskites.
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