An optical fibre-based sensor for the detection of gaseous ammonia with methylammonium lead halide perovskite

Abstract

Highly fluorescent perovskite materials have attracted considerable interest for fundamental research and potential applications. In this work, we demonstrate the recoverable PL quenching of methylammonium lead halides (MAPbX₃, where X is Cl, Br or I) upon exposure to gaseous ammonia that enables the use of hybrid perovskites in gas-sensing applications. XRD analysis confirmed that the MA cations in the perovskite material were replaced by NH₃ to form NH₄PbX₃·MA, thereby resulting in distinct changes in the crystalline structure and, consequently, PL quenching. However, as a weak coordination complex, NH₄PbX₃·MA can be easily thermally decomposed to recover the starting product MAPbX₃ with the release of ammonia. An in-depth understanding of the reversible chemical and structural changes of the perovskites by exposing them to polar molecules such as ammonia can advance the development of hybrid perovskite sensors and provides insights into the mechanisms of how perovskites coordinate with polar molecules.