Function:                 Intern H/F

Contract:                 Internship agreement

Starting date:        As of February 2, 2026 (to be defined)

Duration:                 6 months

Workplace:             IPVF – 18 bd Thomas Gobert, 91120 Palaiseau (France)

Education:               M2, Engineering school in optics, material science, physical science

Ref.:                           PR-C-M-2-ST

IPVF – Institut Photovoltaïque d’Île-de-France

IPVF is a scientific and technical pole dedicated to the research and development of solar technologies. It permanently hosts its own staff, as well as the employees of its partners and external companies. IPVF aims to become one of the world’s leading centers for research, innovation, and training in the field of energy transition.
IPVF primary objective is to improve the performance and competitiveness of photovoltaic cells and develop breakthrough technologies by relying on four levers:

• Ambitious research program.
• The hosting of more than 200 researchers and their laboratories on its Paris-Saclay site.
• A state-of-the-art technology platform (8,000 m²) open to the photovoltaic industry actors, with more than 100 state-of-the-art equipment units located in clean rooms.
• A training program mainly based on a master’s degree, the supervision of PhD students, and continuing education.

Brief history:

The IPVF was founded in 2013 on the initiative of the French government, EDF, TotalEnergies, Air Liquide, CNRS, Ecole Polytechnique, Horiba and Riber. Bringing together more than 150 researchers, our 8,000 square meter Paris-Saclay platform is a unique platform for all types of deeptech research and innovation.

The IPVF aims to remain:
• A world leader in photovoltaic-related R&D. By federating the best French teams in the field of research, innovation and industrial production, in partnership with major international institutes, particularly in Europe,
• A leader in the development of photovoltaic technology bricks in line with market trends,
• A reference in sending the most promising R&D concepts to the industry.

INTERNSHIP CONTEXT

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 Flechas Medina’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.