Impedance Spectroscopy measurements and modelling in multijunction device

🌟 Job offer : Advanced Characterization of Multijunction Devices: Impedance Spectroscopy measurements and modelling 🌟

 📅 Contract type : Internship

⏳Duration : 6 months

📍 Location : Palaiseau (91120)

📚 Formation : M2, Engineering school in data modelling, optics, material science, physical science

🔍 Context :

IPVF Ile-de-France Photovoltaic Institute, is an institute for the energy transition created in 2013. It is a scientific and technical center dedicated to the research and development of solar technologies. Located on Paris-Saclay campus, it brings together its own staff, employees of its partners, and those of external companies. The IPVF aims to become one of the world's leading centers for research, innovation, and training in the field of energy transition.

The IPVF's primary objective is to improve the performance and competitiveness of photovoltaic cells and to develop breakthrough technologies by leveraging four key drivers:

• An ambitious research program;

• Hosting 150 researchers and their laboratories on Paris-Saclay campus

• A cutting-edge technological platform (8,000 m²) open to stakeholders in the photovoltaic industry, and housing more than 100 state-of-the-art equipment units housed in clean rooms.

• A training program mainly based on a master's degree, supervision of doctoral students, and continuing education

UMR-IPVF is a joint resarch unit between IPVF and CNRS, hosting 50 academic researchers, and will lead the internship.

 🔍 Impedance spectroscopy at IPVF :

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. 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 characterization and 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. Impedance spectroscopy (IS) is a powerful and excellent technique to study the different electronic recombination and ionic-electronic dynamics within perovskite-based devices and shed light on where the different mechanisms occurring[1]. Recently, we have successfully interpretated IS data by using numerical drift-diffusion (DD) simulations [1,2]. In addition, in-situ IS during degradation tests was put in place at IPVF during Juan Pablo’s PhD [2]. In this work, we would like to go one step further and implement IS in perovskite-based tandem devices. The IS signal of perovskite-based tandems is much more complex than that of single junction perovskite devices, with overlapping signals complicating the physical interpretation [3]. Last year, the first all-perovskite tandem device was measured by IS from Stranks group[3]. In Geeps, there is already a huge experience on IS measurement in tandem thanks to the PhD thesis of Cyril Léon[4]. The idea is to extend this work to the measurement of perovskite-based tandem devices.

[1] O. Almora, P. López-Varo, et al. Instability analysis of perovskite solar cells via short-circuit impedance spectroscopy: A case study on NiOx passivation. J. Appl. Phys. 136, 094502 (2024)

[2] Thesis Juan Pablo Flechas Medina. Degradation mechanisms analysis of perovskite solar cells and mini-modules: development of methodologies & phenomenological models.

[3] Bart Roose, Petra J Cameron, Samuel D Stranks et al. Electrochemical Impedance Spectroscopy of All-Perovskite Tandem Solar Cells. ACS Energy Lett. 2024, 9, 442-453. [4] Thesis Cyril Léon. Adaptation des techniques de caractérisation basées sur des mesures de capacité et d’admittance aux cellules solaires multijonctions : expériences et modélisation.

📋 Main missions :

In this work, there will be two main parts.

The main task for this internship will be to adapt the IS setup at IPVF to its application to tandem devices by using selective excitation spectrum. In Geeps, admittance spectroscopy measurements can be done.

Second part, there will be the modelling of the IS in tandem devices to interpret the IS data. The samples will be asked at IPVF and from international partner labs from EU projects. This work will help to characterize and discover metastability on the fabricated perovskite solar cells and tandem.

👤 Profile:

Hard skills :

• Instrumentation
• Modelling (matlab, python)
• Data processing
• Material sciences
• Knowledge in impedance spectroscopy is a plus
• Knowledge in photovoltaics is a plus

Soft skills :

• Result and technology oriented
• Innovative
• Autonomous
• Collaborative work

📧 Contacts : Applications to send to [email protected]

🌐 Website: IPVF