Mechanism of Circular Dichroism in Chiral 2D Halide Perovskites

A key motivator for research in hybrid organic-inorganic metal halide perovskites (HOIPs) is the potential to combine distinct characteristics of the inorganic and organic constituents to elicit desirable functional properties. For example, incorporation of chiral organic cations lacking a center of inversion into layered 2D halide perovskites with large spin-obit coupling has been shown to result in structural chirality transfer, leading to Rashba/Dresselhaus-type spin-splitting while at the same time leading to the emergence of chiroptical effects such as circular dichroism (CD) [1,2]. Here we address the question: What is the connection, if any, between the spin textures that emerge by virtue of the structural chirality transfer and the emergence of chiroptical properties associated with the band edge exciton transitions? In this talk we explore the mechanism of excitonic CD in chiral 2D layered perovskites utilizing an analytical k.p/effective mass theory model, parameterized by hybrid density functional theory calculations. We develop analytical expressions for the electric and magnetic dipole transition matrix elements and show the direct connection between particular spin textures and the emergence of CD in these materials [3].<br/><b>Acknowledgements</b><br/>This work was supported through the Center for Hybrid Organic Inorganic Semiconductors for Energy (CHOISE), an Energy Frontier Research Center funded by the Office of Basic Energy Sciences, Office of Science within the US Department of Energy.<br/><br/><b>References</b><br/>1. M. K. Jana <i>et al</i>., Organic-to-inorganic structural chirality transfer in a 2D hybrid perovskite and impact on Rashba-Dresselhaus spin-orbit coupling, <i>Nat. Commun.,</i> 11:4699, (2020).<br/>2. M. K. Jana, <i>et al</i>., Structural descriptor for enhanced spin-splitting in 2D hybrid perovskites, <i>Nat. Commun.,</i> 12:4982, (2021).<br/>3. P. C. Sercel, R. Song, M. P. Hautzinger, V. Blum, and M. C. Beard, Mechanism of circular dichroism in chiral 2D perovskites, in preparation, (2024).