Band Gap-Tunable, Chiral Hybrid Metal Halides Displaying Second-Harmonic Generation

Abstract

The introduction of chirality in lead halide perovskites and related metal halide materials allows for an expansion of their unique and useful properties toward nonlinear optics. However, when synthesizing materials based on less toxic metals antimony and bismuth, the large variability in the crystal structures of their metalates and their tendency to form molecular or chainlike anion motifs can be a challenge when creating tunable materials. Here, we show that using a chiral amine template, we can synthesize an isomorphous family of compoundsand Bi; X = Cl, Br, and I) that combines multiple aspects: the compounds are not only chiral but also feature a trilayered arrangement of cations and anions that allows for facile cleavage and exfoliation. The different combinations of E and X allow for a variation of the onset of absorption between 3.35 and 2.09 eV. Using femtosecond laser spectroscopy, we show that our materials allow for efficient second-harmonic generation. Together with a simple synthesis and good stability, this makes these materials promising candidates for linear and nonlinear optical devices.

Tin‐Based Chiral Perovskites with Second‐Order Nonlinear Optical Properties

“…The polarization dependence tests were conducted by rotating the λ /2 plate to generate linearly polarized light with different directions, in which p ‐polarized (parallel to the plane of incidence) input polarization at 0° angle and fixed linear‐polarized output polarization. The polarization plots (Figure 4d) accorded well with cos 4 θ function, [ 40 ] demonstrating the anisotropy of materials with P 2 1 space group [ 50,53 ] (see details in Supporting Information). The polarization ratio defined as ρ = ( I max – I max )/( I max + I max ) is ≈0.83 for a linearly polarized analyzer and suggests a comparably high sensitivity of SHG to the crystal symmetry.…”

Giant Optical Activity and Second Harmonic Generation in 2D Hybrid Copper Halides

“…For example, Xu and co‐workers determined second‐order nonlinear optical (NLO) coefficient of (R‐/S‐MPEA) 1.5 PbBr 3.5 (DMSO) 0.5 (MPEA=β‐methylphenethylamine) as approximately 0.68 pm V −1 at 850 nm [12] . Very recently, a series of chiral metal halides were manufactured by Heine and co‐workers, [13] and the SHG signals were 5–45 times smaller than the quartz reference.…”

Hybrid Metal‐Halide Infrared Nonlinear Optical Crystals of (TMEDA)MI5 (M = Sb, Bi) with High Stability

“…The organic cations in (TMEDA)SbI 5 and (TMEDA) BiI 5 connect with the adjacent inorganic octahedral chains through hydrogen bonds. This interaction forms a prominently stable structural framework with the higher melting point than some reported OIMHs such as (C 5 H 10 N) 2 BiBr 5 (200 °C), [18] (C 4 H 14 N 2 ) 2 In 2 Br 10 (200 °C), [19] (C 6 H 5 CH 2 NH 3 )InBr 6 (220 °C), [20] (CH 3 NH 3 ) 3 Sb 2 I 9 (253 °C), [21] [22] (C 7 H 7 )BiI 4 (200 °C), and (C 7 H 7 ) SbI 4 (240 °C). [23] Further, the DSC measurement results also indicated that (TMEDA)SbI 5 and (TMEDA)BiI 5 did not undergo a phase change in this temperature range.…”