Large and Small Signal Analysis for exploring of the ionic migration processes, capacitive and inductive effects in perovskite solar cells
Nicolae Filipoiu a b, Amanda Teodora Preda a b c, Dragos-Victor Anghel a b c, Roxana Patru d, Rachel Elizabeth Brophy e, Movaffaq Kateb e, Cristina Besleaga d, Andrei Gabriel Tomulescu d, Ioana Pintilie d, Andrei Manolescu e, George Alexandru Nemnes a b c, Lucian Pintilie d
a University of Bucharest, Faculty of Physics, Magurele-Ilfov 077125, Romania
b Horia Hulubei National Institute for Physics and Nuclear Engineering, Magurele-Ilfov 077126, Romania
c Research Institute of the University of Bucharest (ICUB), Mihail Kogalniceanu Blvd 36-46, Bucharest 050107, Romania
d National Institute of Materials Physics, Magurele, Ilfov 077125, Romania
e Department of Engineering, Reykjavik University, Menntavegur 1, Reykjavik IS-102, Iceland
Poster, Roxana Patru, 030
Publication date: 3rd April 2023

Perovskite solar cells (PSCs) have emerged as a promising alternative to conventional photovoltaic technologies, owing to their remarkable efficiency and low-cost fabrication. However, understanding the underlying mechanisms governing their performance and stability remains a challenge. In this study, we investigate the large and small signal behavior of hybrid CH3NH3PbI2.6Cl0.4 perovskite solar cells to elucidate the capacitive and inductive effects that impact their performance and degradation.

The large signal analysis under varying voltage poling and illumination conditions reveals the influence of scan rate and characteristic time scales on hysteresis magnitude. The small signal analysis, based on electrochemical impedance spectroscopy (EIS) measurements, uncovers the capacitive and inductive effects associated with distinct recombination processes in the bulk electric field and ionic-induced defect recombination. Inductive effects can be related to ionic-induced defects, mostly located at interfaces, whereas capacitive effects are due to the instantaneous electric field in the bulk of the perovskite.

The analysis provides a bridge between charge accumulation models and charge collection models and shows that both models can lead to similar results when the time scale of the slow process is the same. The equivalent circuit model offers valuable insights into the underlying mechanisms responsible for PSC performance and stability [1]. Our findings demonstrate the importance of ion mobility and susceptibility to induce defects for the inductive behavior, highlighting the potential of inductive effects as a quantifiable feature for defect analysis and recovery in monitoring PSC long-term degradation, paving the way for future studies on their stability and performance.

The research leading to these results has received funding from the EEA Grants 2014-2021, under Project Contract No. 36/2021 (Project Code: EEA-RO-NO-2018-0106) and from the Project to Support Institutional Excellence contract 35PFE/2022 (funded by the Romanian Ministry of Research, Innovation and Digitization).

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