Some Considerations about Impedance Analysis in Perovskite Solar Cells
Francisco Fabregat-Santiago a
a Universitat Jaume I, Institute of Advanced Materials (INAM) - Spain, Avinguda de Vicent Sos Baynat, Castelló de la Plana, Spain
Proceedings of International Conference on Impedance Spectroscopy and Related Techniques in Metal Halide Perovskites (PERIMPED)
Online, Spain, 2020 October 6th - 7th
Organizers: Juan Bisquert, Bruno Ehrler and Eline Hutter
Invited Speaker, Francisco Fabregat-Santiago, presentation 019
Publication date: 25th September 2020

The Impedance spectroscopy analysis of perovskite solar cells is a challenging task as lead halide perovskites present many simultaneous phenomena that complicate the modeling and even the way we measure.

One of the great properties of perovskite is its ability to transport electrons and holes with a reasonably good conductivity what, combined with relatively low non radiative recombination, yields to good enough diffusion lengths, allowing an efficient extraction of the charges generated within the device.1 Another key effect is the ability to equilibrate Fermi levels of these electronic carriers at the interfaces at positions very close to conduction and valence band of the perovskite what allows to produce open circuit potentials very close to thermodynamic limits.

At the same time, lead halide perovskites have shown to be good ionic conductors.1, 2 This point helps to explain some of the excellent properties of the material but also complicates the analysis of impedance, the description of the response of the devices at long times and eventually compromises long term stability of the device as the strong internal electrochemical potential attracts ions (or vacancies) towards the interfaces.

In this work some of the effects that ionic interactions have in the impedance and performance of perovskite solar cells will be described, paying special attention to interfacial effects, changes in recombination and their effect on solar cell performance.3, 4  




(1)         Garcia-Fernandez, A.;  Moradi, Z.;  Manuel Bermudez-Garcia, J.;  Sanchez-Andujar, M.;  Gimeno, V. A.;  Castro-Garcia, S.;  Antonia Senaris-Rodriguez, M.;  Mas-Marza, E.;  Garcia-Belmonte, G.; Fabregat-Santiago, F., Effect of Environmental Humidity on the Electrical Properties of Lead Halide Perovskites. Journal of Physical Chemistry C 2019, 123 (4), 2011-2018.

(2)         Li, C.;  Guerrero, A.;  Huettner, S.; Bisquert, J., Unravelling the role of vacancies in lead halide perovskite through electrical switching of photoluminescence. Nature Communications 2018, 9 (1), 5113.

(3)         Alvarez, A. O.;  Arcas, R.;  Aranda, C. A.;  Bethencourt, L.;  Mas-Marzá, E.;  Saliba, M.; Fabregat-Santiago, F., Negative Capacitance and Inverted Hysteresis: Matching Features in Perovskite Solar Cells. The Journal of Physical Chemistry Letters 2020, 11 (19), 8417-8423.

(4)         Fabregat-Santiago, F.;  Kulbak, M.;  Zohar, A.;  Valles-Pelarda, M.;  Hodes, G.;  Cahen, D.; Mora-Sero, I., Deleterious Effect of Negative Capacitance on the Performance of Halide Perovskite Solar Cells. ACS Energy Letters 2017, 2 (9), 2007-2013.

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