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

DOI: 10.1002/adfm.202200454