Humidity Disrupts Structural and Chiroptical Properties of Chiral 2D Perovskites

Chiral two-dimensional (2D) hybrid organic–inorganic metal halide perovskite semiconductors have emerged as an exceptional material platform with many design opportunities for spintronic applications. However, a comprehensive understanding of changes to the crystal structure and chiroptical properties upon exposure to atmospheric humidity has not been established. We demonstrate phase degradation to the 1D (MBA)PbI₃ (MBA = methylbenzylammonium) and the hypothetical (MBA)₃PbI₅·H₂O hydrate phases, accompanied by a reduction and disappearance of the chiroptical response. Firstprinciple simulations show that water molecules preferentially locate at the interface between the organic cations and the inorganic framework, thereby disrupting the hydrogen bonding, impacting both the structural chirality and stability of the material. These findings provide critical insights into phase degradation mechanisms and their impact on chiroptical activity in chiral 2D perovskites.. Authors: Nurdillayeva, Raushan N. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Khoja Akhmet Yassawi International Kazakh-Turkish University (Kazakhstan)] (ORCID:000000019444737X); Moral, Raphael F. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); University of Nevada, Las Vegas, NV (United States)] (ORCID:0000000218444035); Pols, Mike [Eindhoven University of Technology (The Netherlands)] (ORCID:0000000210689599); Lee, Do-Kyoung [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); University of Nevada, Las Vegas, NV (United States)]; Altoe, Virginia [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)]. DOE Contract: AC02-05CH11231; SC0023355. Subjects: 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; DFT calculations; chiral 2D perovskites; chiroptical properties; diffraction; humidity; humidity degradation; perovskites; phase transformation; solvates; thin films