Origin of Intrinsic Chirality in Cysteine‐Passivated Metal Halide Perovskite Nanoclusters

Ligand-assisted perovskite nanoclusters (PNCs) have been synthesized using oleylamine and L- or D-cysteine as confirmed based on their characteristic electronic absorption bands around 430 nm based on ultraviolet-visible spectra. Circular dichroism (CD) spectra show distinct chiroptical bands in the 430-440 nm region, revealing the chirality of the PNCs. Interestingly, the sign of the CD signal is always negative, independent of the chirality for L- or D-cystine. This 430-440 nm CD band is tentatively attributed to the formation of new chiral stereocenters within the PNCs with an uneven ratio of two enantiomers induced by the asymmetric liquid-liquid interface from the solvent and antisolvent used during synthesis.