Small-polaron mediated recombination in titanium dioxide from first principles

Abstract

Nonradiative recombination leads to losses in efficiency in optoelectronic devices such as photovoltaic cells and light-emitting diodes. Charges trapped at point defects or self-trapped as a small polaron may act as recombination centers. Using various phases of titanium dioxide as an example, we provide first-principles predictions that small hole polarons in the bulk of the crystal would exhibit significant rates of recombination with electrons in the conduction band. However, small hole polarons trapped at a model grain boundary are predicted to have much higher nonradiative recombination rates, which can be attributed to softer phonon modes in the vicinity of the boundary as well as greater electron-phonon coupling. These findings have ramifications in materials other than titanium dioxide, and we propose strategies to reduce the degree of recombination that would occur at grain boundaries.

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Item Type:	Article
Authors/Creators:	Quirk, James A. McKenna, Keith P. https://orcid.org/0000-0003-0975-3626
Copyright, Publisher and Additional Information:	Funding Information: K.P.M. acknowledges support from EPSRC (Grants No. EP/P006051/1 and No. EP/P023843/1). This work made use of the facilities of Archer, the UK's national high-performance computing service, via our membership in the UK HPC Materials Chemistry Consortium, which is funded by EPSRC (Grants No. EP/L000202 and No. EP/R029431). This work also made use of the Viking Cluster, which is a high-performance computer facility provided by the University of York. All data created during this research are available by request from the University of York Research database . Publisher Copyright: © 2023 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
Dates:	Accepted: 6 March 2023 Published: 1 May 2023
Institution:	The University of York
Academic Units:	The University of York > Faculty of Sciences (York) > Physics (York)
Depositing User:	Pure (York)
Date Deposited:	01 Jun 2023 09:20
Last Modified:	10 Apr 2025 23:35
Published Version:	https://doi.org/10.1103/PhysRevResearch.5.023072
Status:	Published
Refereed:	Yes
Identification Number:	10.1103/PhysRevResearch.5.023072
Related URLs:	http://www.scopus.com/inward/record.url?...
Open Archives Initiative ID (OAI ID):	oai:eprints.whiterose.ac.uk:199837

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Small-polaron mediated recombination in titanium dioxide from first principles

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