Organic Cation Dynamics in the Layered Lead Iodide Perovskites BA2PbI4and PEA2PbI4

Rasmus Lavén; Michael M. Koza; Niina H. Jalarvo; Marco Moroni; Lorenzo Malavasi; Maths Karlsson

doi:10.1021/acs.jpclett.5c02091

Organic Cation Dynamics in the Layered Lead Iodide Perovskites BA₂PbI₄and PEA₂PbI₄

Rasmus Lavén
, Michael M. Koza
, Niina H. Jalarvo
, Marco Moroni
, Lorenzo Malavasi
, Maths Karlsson

Chemical Spectroscopy

Research output: Contribution to journal › Article › peer-review

Abstract

We report on a quasielastic neutron scattering (QENS) study of the rotational dynamics of organic cations in the optoelectronic layered metal halide perovskites BA₂PbI₄(BA = butylammonium, CH₃(CH₂)₃NH₃) and PEA₂PbI₄(PEA = phenethylammonium, C₆H₅(CH₂)₂NH₃). For BA₂PbI₄, the measurements reveal highly temperature dependent dynamics. Between 100 and 260 K, the dynamics are ascribed to rotational dynamics of the -CH₃and -NH₃groups of the BA cation, whereas above 300 K we also observe the additional presence of full rotations of the whole BA cation around its long molecular axis. For PEA₂PbI₄, the measurements reveal dynamics that are more spatially restricted in nature, i.e., rotational dynamics of the -NH₃groups of the PEA cations for temperatures above 200 K, with no other dynamical processes observed at higher temperatures. A correlation of the dynamics results to literature data on the optical properties of the materials suggests that the more restricted organic cation dynamics in PEA₂PbI₄are related to its longer lifetime and diffusion lengths for charge carriers, as compared to BA₂PbI₄.

Original language	English
Pages (from-to)	10282-10290
Number of pages	9
Journal	Journal of Physical Chemistry Letters
Volume	16
DOIs	https://doi.org/10.1021/acs.jpclett.5c02091
State	Published - Jan 1 2025

Funding

M.K. acknowledges support from the Swedish Research Council (Grants 2016-06958 and 2021-04807) and the Swedish Energy Agency (Grant 48712-1). The authors thank the Institut Laue-Langevin for access to neutron beam facilities. A portion of this research used resources at the Spallation Neutron Sources, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. Erik Fransson and Paul Erhart are acknowledged for discussions on layered metal halide perovskites.

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title = "Organic Cation Dynamics in the Layered Lead Iodide Perovskites BA2PbI4and PEA2PbI4",

abstract = "We report on a quasielastic neutron scattering (QENS) study of the rotational dynamics of organic cations in the optoelectronic layered metal halide perovskites BA2PbI4(BA = butylammonium, CH3(CH2)3NH3) and PEA2PbI4(PEA = phenethylammonium, C6H5(CH2)2NH3). For BA2PbI4, the measurements reveal highly temperature dependent dynamics. Between 100 and 260 K, the dynamics are ascribed to rotational dynamics of the -CH3and -NH3groups of the BA cation, whereas above 300 K we also observe the additional presence of full rotations of the whole BA cation around its long molecular axis. For PEA2PbI4, the measurements reveal dynamics that are more spatially restricted in nature, i.e., rotational dynamics of the -NH3groups of the PEA cations for temperatures above 200 K, with no other dynamical processes observed at higher temperatures. A correlation of the dynamics results to literature data on the optical properties of the materials suggests that the more restricted organic cation dynamics in PEA2PbI4are related to its longer lifetime and diffusion lengths for charge carriers, as compared to BA2PbI4.",

author = "Rasmus Lav{\'e}n and Koza, \{Michael M.\} and Jalarvo, \{Niina H.\} and Marco Moroni and Lorenzo Malavasi and Maths Karlsson",

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doi = "10.1021/acs.jpclett.5c02091",

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AU - Lavén, Rasmus

AU - Koza, Michael M.

AU - Jalarvo, Niina H.

AU - Moroni, Marco

AU - Malavasi, Lorenzo

AU - Karlsson, Maths

PY - 2025/1/1

Y1 - 2025/1/1

N2 - We report on a quasielastic neutron scattering (QENS) study of the rotational dynamics of organic cations in the optoelectronic layered metal halide perovskites BA2PbI4(BA = butylammonium, CH3(CH2)3NH3) and PEA2PbI4(PEA = phenethylammonium, C6H5(CH2)2NH3). For BA2PbI4, the measurements reveal highly temperature dependent dynamics. Between 100 and 260 K, the dynamics are ascribed to rotational dynamics of the -CH3and -NH3groups of the BA cation, whereas above 300 K we also observe the additional presence of full rotations of the whole BA cation around its long molecular axis. For PEA2PbI4, the measurements reveal dynamics that are more spatially restricted in nature, i.e., rotational dynamics of the -NH3groups of the PEA cations for temperatures above 200 K, with no other dynamical processes observed at higher temperatures. A correlation of the dynamics results to literature data on the optical properties of the materials suggests that the more restricted organic cation dynamics in PEA2PbI4are related to its longer lifetime and diffusion lengths for charge carriers, as compared to BA2PbI4.

AB - We report on a quasielastic neutron scattering (QENS) study of the rotational dynamics of organic cations in the optoelectronic layered metal halide perovskites BA2PbI4(BA = butylammonium, CH3(CH2)3NH3) and PEA2PbI4(PEA = phenethylammonium, C6H5(CH2)2NH3). For BA2PbI4, the measurements reveal highly temperature dependent dynamics. Between 100 and 260 K, the dynamics are ascribed to rotational dynamics of the -CH3and -NH3groups of the BA cation, whereas above 300 K we also observe the additional presence of full rotations of the whole BA cation around its long molecular axis. For PEA2PbI4, the measurements reveal dynamics that are more spatially restricted in nature, i.e., rotational dynamics of the -NH3groups of the PEA cations for temperatures above 200 K, with no other dynamical processes observed at higher temperatures. A correlation of the dynamics results to literature data on the optical properties of the materials suggests that the more restricted organic cation dynamics in PEA2PbI4are related to its longer lifetime and diffusion lengths for charge carriers, as compared to BA2PbI4.

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SN - 1948-7185

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EP - 10290

JO - Journal of Physical Chemistry Letters

JF - Journal of Physical Chemistry Letters

ER -

Organic Cation Dynamics in the Layered Lead Iodide Perovskites BA₂PbI₄and PEA₂PbI₄

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