Tailoring Polaron Dimensions in Lead-Tin Hybrid Perovskites

Lei Gao; Heng Zhang; Yong Zhang; Shuai Fu; Jaco J. Geuchies; Donato Valli; Rafikul Ali Saha; Bapi Pradhan; Maarten Roeffaers; Elke Debroye; Johan Hofkens; Junpeng Lu; Zhenhua Ni; Hai I. Wang; Mischa Bonn

doi:10.1002/adma.202406109

Tailoring Polaron Dimensions in Lead-Tin Hybrid Perovskites

Lei Gao, Heng Zhang, Yong Zhang, Shuai Fu, Jaco J. Geuchies, Donato Valli, Rafikul Ali Saha, Bapi Pradhan, Maarten Roeffaers, Elke Debroye, Johan Hofkens, Junpeng Lu^*, Zhenhua Ni^*, Hai I. Wang^*, Mischa Bonn^*

^*Corresponding author for this work

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

Abstract

Charge carriers in the soft and polar perovskite lattice form so-called polaron quasiparticles, charge carriers dressed with a lattice deformation. The spatial extent of a polaron is governed by the material's electron-phonon interaction strength, which determines charge carrier effective mass, mobility, and the so-called Mott polaron density, that is, the maximum stable density of charge carriers that a perovskite can support. Despite its significance, controlling polaron dimensions has been challenging. Here, experimental substantial tuning of polaron dimensions is reported by lattice engineering, through Pb/Sn substitution in CH₃NH₃Sn_xPb_1−xI₃. The polaron dimension is deduced from the Mott polaron density, which can be composition-tuned over an order of magnitude, while charge carrier mobility occurs through band transport, and remains substantial across all compositions, ranging from 10 s to 100 s cm² V s⁻¹ at room temperature. The effective modulation of polaron size can be understood by considering the bond asymmetry after carrier injection as well as the random spatial distribution of Pb/Sn ions. This study underscores the potential for tailoring polaron dimensions, which is crucial for optimizing applications prioritizing either high charge carrier density or high mobility.

Original language	English
Article number	2406109
Journal	Advanced Materials
Volume	36
Issue number	40
Early online date	27 Aug 2024
DOIs	https://doi.org/10.1002/adma.202406109
Publication status	Published - 2 Oct 2024

Bibliographical note

Publisher Copyright:
© 2024 The Author(s). Advanced Materials published by Wiley-VCH GmbH.

Funding

L.G. and H.Z. contributed equally to this work. The authors thank Lucia Di Virgilio, and Wenhao Zheng for fruitful discussions and constructive comments. The authors acknowledge Dr. Carlos Marquez Admade for conducting the essential ICP-OES measurements. R.A.S. thanks Dr. Eduardo Solano, beamline scientist of BL11, NCD-SWEET, for his invaluable assistance during the measurement. E.D. acknowledges the European Research Council (ERC Starting Grant 101117274 X-PECT) and the KU Leuven Internal Funds (STG/21/010, C14/23/090, and CELSA/23/018). J.H. acknowledges the support of the Research Foundation Flanders through SBO PROCEED (FWO grant number S002019N) and of the MPI as a fellow. J.J.G. gratefully acknowledges financial support from the Alexander von Humboldt Foundation. L.G. acknowledges fellowship support from the Chinese Scholarship Council (CSC) and the Postgraduate Research & Practice Innovation Program of Jiangsu Province (No. KYCX22_0240). D.V. acknowledges the support of the Research Foundation Flanders through a doctoral fellowship (FWO Grant Number 1S45223N).

Funders	Funder number
SBO PROCEED
China Scholarship Council
Alexander von Humboldt-Stiftung
KU Leuven	CELSA/23/018, C14/23/090, STG/21/010
Postgraduate Research & Practice Innovation Program of Jiangsu Province	1S45223N, KYCX22_0240
European Research Council	101117274 X‐PECT
Fonds Wetenschappelijk Onderzoek	S002019N

Keywords

Mott polaron density
perovskites
polaron size
polarons
THz spectroscopy

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Advanced Materials - 2024 - Gao - Tailoring Polaron Dimensions in Lead‐Tin Hybrid PerovskitesFinal published version, 1.59 MBLicence: CC BY-NC

Cite this

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abstract = "Charge carriers in the soft and polar perovskite lattice form so-called polaron quasiparticles, charge carriers dressed with a lattice deformation. The spatial extent of a polaron is governed by the material's electron-phonon interaction strength, which determines charge carrier effective mass, mobility, and the so-called Mott polaron density, that is, the maximum stable density of charge carriers that a perovskite can support. Despite its significance, controlling polaron dimensions has been challenging. Here, experimental substantial tuning of polaron dimensions is reported by lattice engineering, through Pb/Sn substitution in CH3NH3SnxPb1−xI3. The polaron dimension is deduced from the Mott polaron density, which can be composition-tuned over an order of magnitude, while charge carrier mobility occurs through band transport, and remains substantial across all compositions, ranging from 10 s to 100 s cm2 V s−1 at room temperature. The effective modulation of polaron size can be understood by considering the bond asymmetry after carrier injection as well as the random spatial distribution of Pb/Sn ions. This study underscores the potential for tailoring polaron dimensions, which is crucial for optimizing applications prioritizing either high charge carrier density or high mobility.",

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AU - Zhang, Heng

AU - Zhang, Yong

AU - Fu, Shuai

AU - Geuchies, Jaco J.

AU - Valli, Donato

AU - Saha, Rafikul Ali

AU - Pradhan, Bapi

AU - Roeffaers, Maarten

AU - Debroye, Elke

AU - Hofkens, Johan

AU - Lu, Junpeng

AU - Ni, Zhenhua

AU - Wang, Hai I.

AU - Bonn, Mischa

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Tailoring Polaron Dimensions in Lead-Tin Hybrid Perovskites

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