Perovskite solar cells have irrupted in the PV world achieving high efficiencies in a small span of time. The combination of the perovskite cells on top of the silicon wafers allows the formation of perovskite-silicon tandem solar cells which are promising candidates to surpass Shockley Queisser single-junction efficiency limitation. However, the stability is still the Achilles heel of perovskite solar devices. One of the most detrimental degradation mechanisms is linked to ion migration[1]. Deeper understanding of the different degradation mechanisms, importantly in which place of the device are occurring, and how the ions affect the perovskite performance is necessary.

In this context, the modelling of perovskite solar cells including ion migration and degradation mechanisms is a crucial tool to significantly contribute to research efforts to improve cell efficiency and device stability. In addition, impedance spectroscopy (IS) [2] is a powerful and excellent technique to study the different ionic-electronic dynamics within perovskite-based devices and shed light on where the different mechanisms occurring. In fact, nowadays, several research centers are focusing on the interpretation of IS by numerical drift-diffusion (DD) simulations. Recently, in-situ IS during degradation tests was put in place at IPVF. A strong IS simulator coupling with machine learning to interpret the experimental data is needed. The main task for this internship will be to learn how to use a previously developed home-made code to perform IS and study the impact of ion migration and degradation mechanisms. Then, the next task will be to extract ionic properties and degradation pathways by interpreting experimental IS data and coupling ML algorithms. This second part will be done in close collaboration with the experimental and characterization teams and other international labs. This work will help to characterize and discover metastability on the fabricated perovskite solar cells. This work will potentially allow the writing of a paper.

[1] P. López-Varo, J. A. Jiménez-Tejada, M. García-Rosell, J. A. Anta, S. Ravishankar, A. Bou, and J. Bisquert. Effects of Ion Distributions on Charge Collection in Perovskite Solar Cells. ACS Energy Letters. 2, 2017

[2] Elizabeth von Hauff and Dino Klotz Impedance spectroscopy for perovskite solar cells: characterisation, analysis, and diagnosis J. Mater. Chem. C, 10, 742, 2022.