A mechanistic investigation of moisture-induced degradation of methylammonium lead iodide

Abstract

We performed in situ x-ray diffraction (XRD) experiments on an inorganic-organic hybrid perovskite, CH 3 NH 3 PbI 3 (MAPbI 3 ), during its interaction with moisture to understand the degradation mechanism. Although the degradation of inorganic-organic hybrid perovskite is an important factor hampering their development as solar cell materials, understanding of the degradation process is currently limited. The moisture-induced degradation mechanism was revealed by the temperature dependence of the in situ XRD pattern sequences and firstprinciples calculations based on the nudged elastic band method. The combination of experimental and computational data suggests that the MAPbI 3 crystal spontaneously changes into the MAPbI 3 mono-hydrate crystal once water molecules activated with an energy of more than $0.6 eV penetrate the (100) outer surface of the MAPbI 3 lattice. These findings have important implications for the development of more robust inorganic-organic hybrid perovskites as light absorbing layers in solar cells and other applications.

Shedding Light on the Moisture Stability of Halide Perovskite Thin Films

“…[ 45 ] In addition to the (CH 3 NH 3 ) 4 PbI 6 .2H 2 O hydrate, another degradation product of monohydrate MAPbI 3 · H 2 O (Equation (1)) was found under high humidity environment (80% RH), along with the additional grain boundaries. [ 46,47 ] Likewise, our previous work also revealed that moisture induced the formation of metastable hydrate phases along with the domain swelling ( Figure 3 a), thus giving rise to the round and pebble‐like crystals (Figure 3b). [ 42 ] The moisture‐induced hydration process is always accompanied by the structure change from 3D crystals to 1D structure and 0 D framework.…”

Photonic Processing of MAPbI3 Films by Flash Annealing and Rapid Growth for High‐Performance Perovskite Solar Cells

“…[20] According to this, it has been shown that HP materials degrade along these sites when both moisture and trapped charges exist simultaneously. [20] Particularly, the presence of water molecules which are known to form hydrates [21,22] allowing charges trapped at the defect site to easily deteriorate the HPs structure. In addition, the aforementioned sites are considered as one of the main reasons for the appearance of hysteresis as defects could provide a favorable pathway for ion migration due to reduced steric hindrance.…”