American Chemical Society
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Optical Constants and Effective-Medium Origins of Large Optical Anisotropies in Layered Hybrid Organic/Inorganic Perovskites

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Version 2 2022-04-19, 18:15
Version 1 2019-09-10, 13:35
posted on 2022-04-19, 18:15 authored by Ryan A. DeCrescent, Naveen R. Venkatesan, Clayton J. Dahlman, Rhiannon M. Kennard, Michael L. Chabinyc, Jon A. Schuller
Hybrid organic/inorganic perovskites (HOIPs) are of great interest for optoelectronic applications due to their quality electronic and optical properties and the exceptional ease of room-temperature synthesis. Layered HOIP structures, e.g., Ruddlesden–Popper phases, offer additional synthetic means to define self-assembling multiple quantum well structures. Measurements of Ruddlesden–Popper HOIP optical constants are currently lacking, but are critical for both a fundamental understanding as well as optoelectronic device design. Here, we use momentum-resolved optical techniques to measure error-constrained complex uniaxial optical constants of layered lead-iodide perovskites incorporating a variety of organic spacer molecules. We demonstrate how large optical anisotropies measured in these materials arise primarily from classical dielectric inhomogeneities rather than the two-dimensional nature of the electronic states. We subsequently show how variations among these materials can be understood within a classical effective-medium model that accounts for dielectric inhomogeneity. We find agreement between experimentally inferred dielectric properties and quantum-mechanical calculations only after accounting for these purely classical effects. This work provides a library of optical constants for this class of materials and clarifies the origins of large absorption and photoluminescence anisotropies witnessed in these and other layered nanomaterials.