Volatility and Chain Length Interplay of Primary Amines: Mechanistic Investigation on the Stability and Reversibility of Ammonia-Responsive Hybrid Perovskites

Hybrid organic–inorganic perovskites possess promising signal transduction properties, which can be exploited in a variety of sensing applications. Interestingly, the highly polar nature of these materials, while being a bane in terms of stability, can be a boon for sensitivity when they are exposed to polar gases in a controlled atmosphere. However, signal transduction during sensing induces irreversible changes in the chemical and physical structure, which is one of the major lacuna preventing its utility in commercial applications. In the context of developing alkylammonium lead(II) iodide perovskite materials for sensing, here we address major issues such as reversibility of structure and properties, correlation between instability and properties of alkylamines, and relation between packing of alkyl chains inside the crystal lattice and the response time toward NH 3 gas. The current investigation highlights that the vapor pressure of alkylamine formed in the presence of NH 3 determines the reversibility and stability of the original perovskite lattice. In addition, close packing of alkyl chains inside the perovskite crystal lattice reduces the response toward NH 3 gas. The mechanistic study addresses three important factors such as quick response, reversibility, and stability of perovskite materials in the presence of NH 3 gas, which could lead to the design of stable and sensitive two-dimensional hybrid perovskite materials for developing sensors.