Solid-State NMR methods for the study of Lead Halide Perovskites

This project focuses on the application of Solid-State Nuclear Magnetic Resonance (SSNMR) to the study of lead halide perovskites (LHPs). LHPs have general formula APbX3, where A is an organic (e.g. methylammonium MA+, formamidinium FA+) or inorganic cation (e.g. Cs+) and X is a halide (I–, Br–, or Cl–). Their main attractive feature is their flexibility: optoelectronic properties can be tuned by changes in the composition, dimensionality, or geometry. Therefore, their structural characterization is fundamental. The advantage of SSNMR arises from the possibility of observing many different NMR-active isotopes, each having several spin properties sensitive to the nuclear environment as well as to interactions and dynamics. In this thesis, state-of-the-art multinuclear solid-state NMR techniques, including both recordings of spectra and measurements of nuclear spin−lattice relaxation times (T1), were employed to investigate a 3D mixed-ion perovskite with chemical formula Cs0.05FA0.81MA0.14PbBr0.45I2.55, 2D Ruddlesden-Popper perovskites with chemical formula BA2MA(n-1)PbnI(3n+1) (with n=1, 2, 3, 4), and CsPbBr3 perovskite nanocubes.