Abstract:

Hybrid perovskites show piezoelectric properties due to polarization and centro-symmetry breaking of PbX₆ pyramids (X = I-, Br-, Cl-). This study examines the piezoelectric response of quasi-2D perovskites using various barrier molecules: benzyl amine (BzA), phenylethyl amine (PEA), and butyl diamine (BuDA). Utilizing piezoelectric force microscopy measurements, we determine the piezoelectric coefficient (d₃₃) where BuDA exhibits a substantial response with values of 147 pm V^–1 for n = 5, better than the other quasi-2D and 3D perovskite counterparts. Density functional theory calculations reveal distorted bond angles in the PbBr₆ pyramids for quasi-2D perovskites, enhancing symmetry breaking. Additionally, polarizabilities and dielectric constants, derived from ab initio many-body perturbation theory, are highest for BuDA, followed by PEA and BzA, aligning with experimental results. We demonstrate pressure sensor performance, emphasizing the quicker capacitance decay time of the quasi-2D perovskite based on BuDA. This research underscores the impact of perovskite dimensionality on piezoelectricity, paving the way for the development of sensitive and wide-ranging pressure sensors.