STAGE – CNRS – Multiscale characterization of photovoltaic materials


Function :                Intern

Contract :               CNRS internship agreement

Starting date:        February/march 2024

Duration:                 6 months

Workplace:             C2N – 10 boulevard Thomas Gobert, 91120 Palaiseau

                                 IPVF – 18 boulevard Thomas Gobert, 91120 Palaiseau

Education:              Master 2


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.


The candidate will work with several members of the sunlit team (C2N) and in close collaboration with the “Institut photovoltaïque d’Ile-de-France” (IPVF).
Websites: , ,

Description of the CL setup and recent publications:




In the past years, photovoltaics (PV) became one of the cheapest sources of energy. 95% of commercial solar cells are made of silicon, and their lab-scale record efficiencies of 26.7 % are now close to the theoretical limit (29.4 %). Yet, expectations of both the society and the PV industry are still high, and most of the research efforts are now dedicated to pushing forward the efficiency of solar cells. Silicon-based tandem devices are the most-regarded solutions for next-generation photovoltaics. To keep low costs and preserve the silicon bottom cell, low-temperature deposition is mandatory for the top cell. Current options are polycrystalline, high-bandgap semiconductors like hybrid perovskites and inorganic Cu(In,Ga)(S,Se)2 -CIGS- or CdTe thin films, but they are still limited by both efficiency and/or stability issues that are hardly explained by current models. Further developments require a better understanding of the properties and limitations of low-cost thin-film materials. In particular, it is necessary to differentiate the properties of grain interiors and grain boundaries, and the macroscopic fluctuations that may occur in semiconductor alloys.




The goal of this project is to use and to combine cathodoluminescence and photoluminescence techniques to provide a multiscale analysis of materials and devices. Elementary processes and properties of bulk materials (doping levels, diffusion length, carrier lifetime, defect levels and densities…) and surfaces (surface recombination velocity, density of defects, surface charges…) will be determined quantitatively down to the nanometer scale, and then mapped on large surface areas and linked to the macroscopic properties of devices. A long-term objective is to use advanced computational methods for correlative data analysis, and simulation to build a realistic model of thin-film solar cells using the measured quantities.

This internship will first focus on the unique cathodoluminescence (CL) tool available at C2N. Its basic principle is the following: a material is excited with an electron beam in a scanning electron microscope (SEM), providing a spatial resolution of 10 nm. Secondary electrons (SE) are collected to form an SEM image, and emitted photons (cathodoluminescence, CL) are collected simultaneously to acquire an hyperspectral image (luminescence spectrum at each point of the map). Time-resolved CL is also available to measure the luminescence decay after a pulsed excitation.

The candidate will be first trained on the CL/TRCL tool. Then, she/he will use this technique to perform and analyze multiscale CL/TRCL mapping, with the goal to develop new methods to reveal the dynamics of carriers (lifetime, diffusion length, recombination velocities at interfaces…) and correlate these properties to the functional parameters of solar cells.



Student in M2 with a solid knowledge in semiconductor physics and optics.
Possibility to continue with a PhD grant on multiscale characterization of PV materials in 2024.



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