#unpublish, compiled

Perovskite to moisture

The perovskite structure tent to hydrolyse, undergoing irreversible degradation and decomposing back into precursors.

For example:
highly hygroscopic $C H_{3} N H_{3} X$ and $C H (N H_{2})_{2} X$ salts and $P b X_{2}$ with X= halide.

the process can be accelerated by heat, electric field, and ultraviolet exposure.

How to mitigate

adding cross-linking additives or by compositional engineering:
- adding combination of $P b (C H_{3} C O_{2})_{2}$ $3 H_{2} O$ and $P b C l_{2}$ in the precursors
- using cation cascade: Cs and Rb cations --> also reduce material photo-instability and/or optimize the film morphology
Using a buffer layer between HTM and the perovskite
Using moisture-blocking HTM such as $N i 0_{x}$

NATURE COMMUNICATIONS | DOI: 10.1038/ncomms15684