High stability and moderate second-order nonlinear optical properties of hybrid lead-free perovskite [(CH3)3NCH2Cl]CdCl3 bulk crystals.

By combining stereochemically active lone-pair d¹⁰ metal Cd²⁺ with halogen anions was identified as an effective method to obtain enhanced nonlinear optical (NLO) materials. In this work, hybrid lead-free perovskite [Me₃NCH₂Cl]CdCl₃ (abbreviated as (TMCM)CdCl₃) bulk crystals were grown by the solution method, which demonstrates the one-dimensional chainlike perovskite structure with distorted {CdCl₆} irregular octahedrons. The environmental, temperature, and atmospheric stabilities were systematically evaluated with a reversible transition and the phase decomposition point were determined at 125 and 271 °C, respectively. In addition, high environmental and high solvent atmospheric stability were also detected. A wide transparent region (200–900 nm) and wide band gap of 5.24 eV were determined with a moderate second harmonic generation (SHG) response of 0.73 times that of KH₂PO₄. Furthermore, theoretical calculations were performed to investigate the relationship between structure and performance, and an applicable birefringence of 0.043 was calculated at 1064 nm. All the results make (TMCM)CdCl₃ a promising candidate for NLO material, which may also have potential applications in the solar-blind UV region. [ABSTRACT FROM AUTHOR]