Large exchange-driven intrinsic circular dichroism of a chiral 2D hybrid perovskite

Shunran Li; Xian Xu; Conrad A Kocoj; Chenyu Zhou; Yanyan Li; Du Chen; Joseph A Bennett; Sunhao Liu; Lina Quan; Suchismita Sarker; Mingzhao Liu; Diana Y Qiu; Peijun Guo

doi:10.1038/s41467-024-46851-2

Large exchange-driven intrinsic circular dichroism of a chiral 2D hybrid perovskite

Nat Commun. 2024 Mar 22;15(1):2573. doi: 10.1038/s41467-024-46851-2.

Authors

Shunran Li^#^{1

2}, Xian Xu^#^{2

3}, Conrad A Kocoj^{1

2}, Chenyu Zhou⁴, Yanyan Li^{1

2}, Du Chen^{1

2}, Joseph A Bennett^{2

5}, Sunhao Liu⁶, Lina Quan^{6

7}, Suchismita Sarker⁸, Mingzhao Liu⁴, Diana Y Qiu^{9

10}, Peijun Guo^{11

12}

Affiliations

¹ Department of Chemical and Environmental Engineering, Yale University, New Haven, CT, USA.
² Energy Sciences Institute, Yale University, West Haven, CT, USA.
³ Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, USA.
⁴ Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY, USA.
⁵ Department of Chemistry, Yale University, New Haven, CT, USA.
⁶ Department of Chemistry, Virginia Tech, Blacksburg, VA, USA.
⁷ Department of Materials Science and Engineering, Virginia Tech, Blacksburg, VA, USA.
⁸ Cornell High Energy Synchrotron Source, Cornell University, Ithaca, NY, USA.
⁹ Energy Sciences Institute, Yale University, West Haven, CT, USA. diana.qiu@yale.edu.
¹⁰ Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, USA. diana.qiu@yale.edu.
¹¹ Department of Chemical and Environmental Engineering, Yale University, New Haven, CT, USA. peijun.guo@yale.edu.
¹² Energy Sciences Institute, Yale University, West Haven, CT, USA. peijun.guo@yale.edu.

^# Contributed equally.

Abstract

In two-dimensional chiral metal-halide perovskites, chiral organic spacers endow structural and optical chirality to the metal-halide sublattice, enabling exquisite control of light, charge, and electron spin. The chiroptical properties of metal-halide perovskites have been measured by transmissive circular dichroism spectroscopy, which necessitates thin-film samples. Here, by developing a reflection-based approach, we characterize the intrinsic, circular polarization-dependent complex refractive index for a prototypical two-dimensional chiral lead-bromide perovskite and report large circular dichroism for single crystals. Comparison with ab initio theory reveals the large circular dichroism arises from the inorganic sublattice rather than the chiral ligand and is an excitonic phenomenon driven by electron-hole exchange interactions, which breaks the degeneracy of transitions between Rashba-Dresselhaus-split bands, resulting in a Cotton effect. Our study suggests that previous data for spin-coated films largely underestimate the optical chirality and provides quantitative insights into the intrinsic optical properties of chiral perovskites for chiroptical and spintronic applications.

Abstract

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