Chiral organic–inorganic hybrid perovskites (OIHPs) are inversion-asymmetric and have many remarkable properties, including circular dichroism, optical rotation, nonlinear optics, and second-harmonic generation (SHG). Although chiral molecules are responsible for chiroptical properties, they are generally not expected to influence the crystallization of OIHPs. Here, we find that OIHPs synthesized with pristine S- and R-molecules crystallize as 1D perovskites, whereas those synthesized with the racemic molecule crystallized as 2D perovskites. Single crystal X-ray diffraction reveals that the structure change is related to the differing packing of chiral molecules versus racemic ones in OIHPs. Furthermore, we demonstrate that chiral OIHPs containing the S- or R-ligands could be applied in circularly polarized light detectors.

Chiral perovskites have attracted considerable attention as excellent spin-emitting materials for applications in spintronics, quantum optics, and biological. Especially in drug development of biological, weak chirality molecules are frequently selected to reduce the side effects of toxics, and there is a common defect for accurately detecting the weak chirality with common methods at room temperature. In this study, formamidine lead bromide perovskite nanocrystals (FAPbBr3 NCs) were coated with chiral ligands, whose chirality was too weak to be observed in the visible region at room temperature. Thus, by characterizing the transverse shift of photonic spin Hall effect (SHE), the accurate discrimination of weak chirality in the visible region was achieved successfully. By measuring the shift value and light spot splitting of photonic SHE at the same concentration, NEA-coated FAPbBr3 NCs can effectively enhance the chirality of naphthalene ethylamine (NEA) ligands when under the mutually reinforcement of chiral molecular and inorganic parts. In addition, we furtherly clearly distinguished the tiny chiral distinction of NEA-coated FAPbBr3 NCs with different particle sizes, which revealed that the chirality decreases with the increase of particle size. These findings could provide effective solutions for the detection and application of weak chirality in hybrid perovskite nanocrystals in universal environment.

Cesium lead halide perovskite nanocrystals (PNCs) have attracted great attention in optoelectronic devices due to their excellent optical properties, such as tunable emission wavelengths, long carrier lifetime, and narrow full width at half-maximum (fwhm). However, the poor stability of PNCs in water or humid environments greatly limits their wide-spreading applications. It is challenging to prepare PNCs with long-term stability in water. Herein, we successfully prepared CsPbBr3@PDMS microspheres by using the emulsification method. Due to the protection of the PDMS layer, the CsPbBr3@PDMS microspheres exhibit good optical properties and stability in water, acid, and alkali solutions. In addition, to expand the application of CsPbBr3 NCs in flexible optical devices and wearable devices, we first prepared stretchable, stable, and photoluminescent hydrogel with a CsPbBr3@PDMS microsphere (hydrogel/CsPbBr3@PDMS) by using the emulsification method. The hydrogel/CsPbBr3@PDMS elastomer exhibits good stability and stretchability. Furthermore, the hydrogel/CsPbBr3@PDMS elastomer retains bright green emission and stability under different mechanical deformations. This work provides a method to improve the CsPbBr3 PNCs with high stability by emulsification, which could also expand the applications of PNCs in underwater display, wearable, and flexible optoelectronic devices.

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