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The Structural Origin of Chiroptical Properties in Perovskite Nanocrystals with Chiral
Organic Ligands
March 16, 2022
Colloidal metal halide perovskite nanocrystals (PNCs) provide an outstanding platform
for exploring chirality-mediated electro-optical phenomena. This system combines the
strong spin-orbit coupling and controllable Rashba-Dresselhaus splitting in metal-halide
perovskites with the extensive tunability afforded by surface ligand attachment, which
in this case can be chiral molecules. Chiral ligands attached to the surface of PNCs
promote the controlled absorption and luminescence of circularly polarized light,
which has been observed. However, the physics behind the mechanism(s) by which chiral
ligands or the surrounding media impart chiroptical response in PNCs is still ambiguous,
which, in this work, we aim to understand more thoroughly.
Scientific Achievement
We studied how chiral methylbenzylammonium (R-/S-MBA) ligands structurally distort
PNCs leading to chiroptical effects like circular dichroism, circularly polarized
luminescence, and spin polarized carrier transport.
Significance and Impact
"Chiral transfer" can occur through either electronic state mixing from the perovskite
semiconductors and chiral ligands or structural distortions from chiral attachment.
The effects are difficult to isolate. Here, we determine that ligands create a structural
distortion extending multiple unit cells from the surface attachment.
Research Details
Probed properties of chiral ligated PNCs
Employed density-functional theory (DFT) to study the structural distortion within
perovskite slab models with chiral lattice termination
Built a circularly polarized light detector with 14% discrimination between right
and left polarized light
