Halide exchange in (ClEA)2PbI4 and its effect on the structural and electronic properties of perovskite layers

Abstract

Two-dimensional organic–inorganic hybrid perovskites exhibit significant application potential in the field of optoelectronic devices owing to their excellent optoelectronic properties and structural tunability. This study for the first time reports the halide exchange phenomenon of (ClEA)₂PbI₄, where ClEA = 2-chloroethylamine. Crystal structure analysis was conducted using nuclear magnetic resonance (NMR), X-ray diffraction (XRD), and thermal analysis. Results indicate that (ClEA)_2−x(IEA)_xPbI_4−xCl_x (x ≤ 0.66, where IEA = 2-iodoethylamine) is formed under high-temperature conditions. Additionally, first-principles calculations were employed to investigate the changes in structure and properties of the material before and after high-temperature treatment. This specific ion exchange reaction between halogenated organic cations and inorganic layers provides a feasible approach for the molecular design of two-dimensional perovskites from the dual perspectives of crystal structure regulation and optoelectronic property optimization.