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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 4: Perovskite and photovoltaics I (joint session HL/KFM)

KFM 4.3: Talk

Monday, March 18, 2024, 10:00–10:15, EW 203

Enhanced Circular Dichroism and Polarized Emission in an Achiral, Low Bandgap Bismuth Iodide Perovskite — •Philip Klement¹, Jakob Möbs², Gina Stuhrmann³, Lukas Gümbel¹, Marius Müller¹, Johanna Heine², and Sangam Chatterjee¹ — ¹Institute of Experimental Physics I, JLU Gießen, Germany — ²Department of Chemistry, PUM, Marburg, Germany — ³Institute of Nanotechnology (INT), KIT, Eggenstein-Leopoldshafen, Germany

Lead halide perovskites and related materials incorporating chiral organic cations exhibit intriguing properties such as chiroptical activity and chirality-induced spin selectivity enabling the generation and detection of circularly polarized light. However, understanding the structural origin of chiroptical activity presents a challenge due to macroscopic factors and experimental constraints. Here, we present the achiral perovskite derivative [Cu₂(pyz)₃(MeCN)₂][Bi₃I₁₁] (pyz = pyrazine; MeCN = acetonitrile), which displays remarkable circular dichroism (CD) arising from the material*s noncentrosymmetric structure. CuBiI exhibits a low, direct optical band gap of 1.70 eV and both linear and circular optical activity with a substantial anisotropy factor of up to 0.16. Intriguingly, despite the absence of chiral building blocks, CuBiI exhibits a substantial degree of circularly polarized photoluminescence, reaching 4.9%. This value is comparable to the results achieved by incorporating chiral organic molecules into perovskites, typically ranging from 3 to 10% at zero magnetic field. Our findings shed light on the macroscopic origin of CD and provide valuable insights for the design of materials with high chiroptical activity.

Keywords: perovskite; polarization; dichroism; chirality