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Avoiding ionic interference in the computation of ideality factor for perovskite solar cells and an analytical theory for their impedance spectroscopy response

Avoiding ionic interference in the computation of ideality factor for perovskite solar cells and an analytical theory for their impedance spectroscopy response
Avoiding ionic interference in the computation of ideality factor for perovskite solar cells and an analytical theory for their impedance spectroscopy response
Impedance spectroscopy (IS) is a straightforward experimental technique that is commonly used to obtain information about the physical and chemical characteristics of photovoltaic devices. However, the non-standard physical behaviour of perovskite solar cells (PSCs), which are heavily influenced by the motion of mobile ion vacancies, has hindered efforts to obtain a consistent theory of PSC impedance. This work rectifies this omission by deriving a simple analytic model of the impedance response of a PSC from the underlying drift-diffusion model of charge carrier dynamics and ion vacancy motion, via an intermediate model that shows extremely good agreement with the drift-diffusion model in the relevant parameter regimes. Excellent agreement is demonstrated between the analytic impedance model and the much more complex drift-diffusion model for applied biases (including both open circuit and the maximum power point at 0.1- and 1-Sun) close to the cell’s built-in voltage Vbi. Both models show good qualitative agreement to experimental IS data in the literature and predict many of the observed anomalous features found in impedance measurements on PSCs. The analytic model provides a practical and useful tool with which to interpret PSC impedance data and extract physical parameters from IS experiments. We define a physical parameter, nel (the electronic ideality factor), that is of particular significance to PSC physics, since, in contrast to the apparent ideality factor, the value of nel can be used to identify the dominant source of recombination in the cell independent of its ionic properties.
Perovskite solar cell, impedance spectroscopy, drift-diffusion modeling
2331-7019
Bennett, Laurence John
47f7f665-ea9f-45fb-a4d6-aad39b6fbff4
Riquelme, Antonio
fa97839b-8680-4501-85ad-b214f8d9daa0
Courtier, Nicola Elizabeth
9c4e0fa1-e239-4a4b-aa70-af65f8b0a524
Anta, Juan
e7d592d1-0b61-4f28-949a-2c4ba012fe02
Richardson, Giles
3fd8e08f-e615-42bb-a1ff-3346c5847b91
Bennett, Laurence John
47f7f665-ea9f-45fb-a4d6-aad39b6fbff4
Riquelme, Antonio
fa97839b-8680-4501-85ad-b214f8d9daa0
Courtier, Nicola Elizabeth
9c4e0fa1-e239-4a4b-aa70-af65f8b0a524
Anta, Juan
e7d592d1-0b61-4f28-949a-2c4ba012fe02
Richardson, Giles
3fd8e08f-e615-42bb-a1ff-3346c5847b91

Bennett, Laurence John, Riquelme, Antonio, Courtier, Nicola Elizabeth, Anta, Juan and Richardson, Giles (2022) Avoiding ionic interference in the computation of ideality factor for perovskite solar cells and an analytical theory for their impedance spectroscopy response. Physical Review Applied. (In Press)

Record type: Article

Abstract

Impedance spectroscopy (IS) is a straightforward experimental technique that is commonly used to obtain information about the physical and chemical characteristics of photovoltaic devices. However, the non-standard physical behaviour of perovskite solar cells (PSCs), which are heavily influenced by the motion of mobile ion vacancies, has hindered efforts to obtain a consistent theory of PSC impedance. This work rectifies this omission by deriving a simple analytic model of the impedance response of a PSC from the underlying drift-diffusion model of charge carrier dynamics and ion vacancy motion, via an intermediate model that shows extremely good agreement with the drift-diffusion model in the relevant parameter regimes. Excellent agreement is demonstrated between the analytic impedance model and the much more complex drift-diffusion model for applied biases (including both open circuit and the maximum power point at 0.1- and 1-Sun) close to the cell’s built-in voltage Vbi. Both models show good qualitative agreement to experimental IS data in the literature and predict many of the observed anomalous features found in impedance measurements on PSCs. The analytic model provides a practical and useful tool with which to interpret PSC impedance data and extract physical parameters from IS experiments. We define a physical parameter, nel (the electronic ideality factor), that is of particular significance to PSC physics, since, in contrast to the apparent ideality factor, the value of nel can be used to identify the dominant source of recombination in the cell independent of its ionic properties.

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Accepted/In Press date: 16 August 2022
Keywords: Perovskite solar cell, impedance spectroscopy, drift-diffusion modeling

Identifiers

Local EPrints ID: 470876
URI: http://eprints.soton.ac.uk/id/eprint/470876
ISSN: 2331-7019
PURE UUID: 3c412db8-21bf-40e4-90c7-afd9b3d7dcd2
ORCID for Laurence John Bennett: ORCID iD orcid.org/0000-0002-0152-1401
ORCID for Giles Richardson: ORCID iD orcid.org/0000-0001-6225-8590

Catalogue record

Date deposited: 20 Oct 2022 16:44
Last modified: 31 Jan 2023 02:43

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Contributors

Author: Laurence John Bennett ORCID iD
Author: Antonio Riquelme
Author: Nicola Elizabeth Courtier
Author: Juan Anta

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