Ligand‐Assisted Self‐Assembly of 3D Perovskite Nanocrystals into Chiral Inorganic Quasi‐2D Perovskites (n = 3) with Ligand‐Ratio‐Dependent Chirality Inversion

Abstract

Chiral inorganic quasi‐2D perovskites are prepared by self‐assembling 3D perovskites in solution for the first time. The quasi‐2D perovskite synthesized is a pure‐phase perovskite with <n> = 3 and is periodically arranged, which is a big breakthrough in quasi‐2D inorganic perovskites. With the individual chiral CsPbBr3 nanocrystals (NCs) assemble into quasi‐2D perovskite, the g‐factor significantly improved (≈5 × 10−3). In addition, the chiroptical activity of quasi‐2D perovskites is explored to be improved with the lateral size increasing. In the first stage of assembly, chiral optical activity is increased due to the lateral size‐dependent optical activity, while the changes in the later stages are attributable to the chiral morphology. Interestingly, chirality inversion is found to be correlated to the number of ligands. It is believed that different conformers of chiral ligands caused by steric hindrance of the original ligand oleylamine result in opposite circular dichroism (CD) polarities. The chirality inversion phenomenon is universal, regardless of the choice of ligands. This work opens up a new path for the synthesis of quasi‐2D perovskites and provides more opportunities for the modulation of chiral optical activity.

Chiral Assembly of Perovskite Nanocrystals: Sensitive Discrimination of Amino Acid Enantiomers

“…According to the collective effect of assemblies, , decomposition of the assemblies and the breaking of the chiral PNA into smaller subdomains of random orientations led to a weakening of CD absorption to near zero. A recent study on the self-assembly of 3D CsPbBr 3 nanocrystals found that assembly can enhance the chiral signal, while the substitution of surface molecules causes chiral inversion . In this work, the reversal of CD signals indicating the substitution of Pro to Phe affects the chirality of PNA.…”

“…Because of the fact that only l - or d -Phe serves as the ligand during the synthesis process, l - and d -Phe did not exhibit visible CD peaks at around 300 nm . Previous studies have shown that self-assembly of perovskite can induce stronger chiral signals in perovskite . In this regard, the chiral optical activity of PNA may be attributed to assembly enhanced chiral transfer and chiral induction.…”

“…This coordination pattern is consistent with the reported synthesis of chiral perovskites using other amino acids as ligands. 8,31 The spectra of C 1s, Cs 3d, Pb 4f, and Br 3d are shown in Figure S2c−f and Figure S3c−f. The morphology of LPNA and DPNA was characterized by transmission electron microscopy (TEM).…”

“…35 Previous studies have shown that self-assembly of perovskite can induce stronger chiral signals in perovskite. 31 In this regard, the chiral optical activity of PNA may be attributed to assembly enhanced chiral transfer and chiral induction. (Figure 2a).…”

Phase Control and Singlet Energy Transfer Enabled by Trimethylamine Modified Boron Dipyrromethene for Stable CsPbBr3 Quantum Wells

“…A sequence of diffraction peaks at angles (3.29°, 6.63°, 8.24°, 11.69°, 13.29°, 16.54°) was observed, signifying the emergence of a perovskite QWs with n = 3. [21] Concurrently, discernible periodic diffractions at lower angles indicated an abundance of nanoplatelets stacking within the samples. Moreover, the peaks of BDP-TMA-CsPbBr 3 displayed a low-angle deviation relative to the CsPbBr 3 , suggesting an augmentation in unit cell parameters and volume upon the incorporation of the large BDP-TMA molecule into the layered perovskites.…”