Title: Probing structural and dynamic properties of MAPbCl3 hybrid perovskite using Mn2+ EPR

Authors: Gediminas Usevičius, Justinas Turčak, Yuxuan Zhang, Andrea Eggeling, Žyginta Einorytė, Michael Allan Hope, Šarūnas Svirskas, Daniel Klose, Vidmantas Kalendra, Kęstutis Aidas, Gunnar Jeschke, Jūras Banys, and Mantas Šimėnas

DOI: https://doi.org/10.1039/d4dt00116h

Date: 04/02/2024

Working Group: WG2

Grant Period: 2nd GP 2023-2024

Grant Period Goal (number): GAPG-4 (3)

Countries involved: Lithuania, Switzerland

Number of female/young/ITC coauthors: 2/5/8

Abstract: Hybrid methylammonium (MA) lead halide perovskites have emerged as materials exhibiting excellent photovoltaic performance related to their rich structural and dynamic properties. Here, we use multifrequency (X-, Q-, and W-band) electron paramagnetic resonance (EPR) spectroscopy of Mn2+ impurities in MAPbCl3 to probe the structural and dynamic properties of both the organic and inorganic sublattices of this compound. The temperature dependent continuous-wave (CW) EPR experiments reveal a sudden change of the Mn2+ spin Hamiltonian parameters at the phase transition to the ordered orthorhombic phase indicating its first-order character and significant slowing down of the MA cation reorientation. Pulsed EPR experiments are employed to measure the temperature dependences of the spin-lattice relaxation T1 and decoherence T2 times of the Mn2+ ions in the orthorhombic phase of MAPbCl3 revealing a coupling between the spin center and vibrations of the inorganic framework. Low-temperature electron spin echo envelope modulation (ESEEM) experiments of the protonated and deuterated MAPbCl3 analogues show the presence of quantum rotational tunneling of the ammonium groups, allowing to accurately probe their rotational energy landscape.

 

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