Chiral nanomaterials have drawn extensive attention on account of numerous application prospects in optoelectronics, asymmetric catalysis, chiral recognition, and three-dimensional (3D) display. Thereinto, chiral perovskite has been a hotspot due to brilliant optoelectronic properties, but some problems limit the development, including low quantum yield, low chiral intensity, and the lack of facile regulation. To overcome these issues, an effective ligand exchange strategy, i.e. the interface modification has been proposed for chiral perovskite nanocrystals (PNCs). With the surface modification of CsPbBr3 PNCs with chiral organic ammonium in methyl acetate in the typical purification process, excellent circular dichroism (CD) signals were obtained and defects were eliminated, leading to an increase in the photoluminescence quantum yield (PLQY) from 50% to nearly 100%. The CD signal can be regulated through a ligand exchange strategy in the longitudinal dimension, the chiral intensity, and the transverse dimension, the wavelength range. Here, the proper addition of R-α-PEAI into the R-α-PEABr-capped CsPbBr3 PNCs can produce a superstrong CD signal with the highest anisotropy factor (g-factor) of 0.0026 in the visible region among reported chiral colloidal PNCs. Simultaneously, the luminescence emission can be tuned from the green to red region with boosted PLQY through the approach. The density functional theory (DFT) calculation result supports that chirality comes from the hybridization between the energy level of a perovskite structure and that of chiral organic molecules. These properties can be used in the structural engineering of high-performance chiral optical materials, spin-polarized light-emitting devices, and polarized optoelectronic devices.

Chiral perovskites have various applications in nonlinear optics due to their asymmetric structures. Currently, nonlinear optical studies have focused on lead‐based perovskite. However, the toxic element, Pb, hinders their further applications. Herein, (R/S‐MBA)4Bi2Br10 (MBA = α‐phenylethylamine) and (R/S‐MPA)2BiBr5 (MPA = 1‐phenylpropan‐1‐amine) crystals were synthesized and explored about the nonlinear optics. Both pairs of chiral perovskite enantiomers exhibit good thermal stability and symmetric circular dichroism signals. Interestingly, MPA and MBA differ by only one methylene but show significant differences in the crystal structures synthesized under the same conditions. The (R/S‐MBA)4Bi2Br10 crystal is a zero‐dimensional (0D) structure in which the [Bi2Br10]4– dimer is spaced by an organic amine. (R/S‐MPA)2BiBr5 crystals are 1D structures in which [BiBr6]2– units form infinitely extended chains by angle sharing. The crystals exhibit efficient second harmonic generation response, and the intensity of (R‐MPA)2BiBr5 is four times that of (R‐MBA)4Bi2Br10 at 980 nm excitation wavelength. The 1D infinitely extended inorganic chain in (R‐MPA)2BiBr5 allows for a more regular arrangement of chiral organic amines, and adjacent organic amines are arranged differently, together leading to its stronger non‐centrosymmetry, which is the decisive factor of nonlinear optics. The study guides the design and deep research of novel second‐order nonlinear optical materials.

Recently, chiral hybrid organic-inorganic perovskites (HOIPs) are drawing wide attention due to their intrinsic noncentrosymmetric structures which result in fascinating properties such as ferroelectronics and second-order nonlinear optics (NLO). However,...