Abstract: 

Over the last decades, the development of alternative space photovoltaic (PV) solutions to the III-V premium standard has shifted the focus to silicon solar cells, the technology that has historically powered satellites for decades. Indeed, leveraging on existing maturity of terrestrial PV silicon devices and processes offers significant potential for innovation and cost reduction. However, the standard terrestrial Si PV solutions face reliability challenges in space environment(1), for instance to maintain the module assembly integrity & high PV performances against thermal cycles(2) and irradiations(2,3), respectively. Therefore, the adaptation of silicon modern photovoltaics cells and packaging for long lasting power supply in space requires proper understanding of their materials ageing mechanisms. 

Many satellites nowadays evolve in Low Earth Orbit, a particularly proton and electron rich environment. Such irradiations induce electrically active defects in the monocrystalline silicon solar cells absorber(4) (essentially due to atomic displacement) which affect in particular the charge carrier lifetime and therefore the PV performances. Interestingly, some of the irradiation-induced defects can be healed upon external factors such as temperature and/or photons flux. For instance, recent investigations reported quasi full recovery of silicon heterojunction solar cell performances, achieved at temperatures below 100°C (conditions similar to operational conditions)(5). 

The main goals of this PhD thesis will be to: 

- Understand the bulk & interface electron/proton irradiation-induced degradation mechanisms driving the evolution of the optoelectronic properties of silicon passivated contacts solar cells. 

- Develop a comprehensive understanding of the self-healing effects in irradiated modern silicon solar cells through experimental studies and modeling. 

- Identify design/fabrication process routes to control & boost the self-healing capability. 

To reach these goals, this PhD work will go through defined steps: bibliography review, silicon solar cells fabrication and characterization, material/device ageing under proton & electron irradiations, advanced characterizations and modeling. These steps will be conducted iteratively over the three years. This PhD work will be conducted at CEA-INES (Le Bourget du Lac, FR) with frequent interactions with CNES (Toulouse, FR) facilities.

References: 

(1) Y. Lu et al., A Review of the Space Environment Effects on Spacecraft in Different Orbits, IEEE Access, vol. 7, 2019. 

(2) L. Perrotin et al., Thermomechanical damages in the vicinity of wires in photovoltaics assemblies exposed to large amplitude thermal cycling, Solar Energy Materials and Solar Cells, vol. 294, 2026. 

(3) R. Cariou et al., Investigation of p-Type Silicon Heterojunction Radiation Hardness, IEEE Journal of Photovoltaics, vol. 14, 2024. 

(4) O. Guillot et al., Influence of Material Composition and Wafer Thickness on the Performances of Electron Irradiated Gallium-Doped Silicon Heterojunction Solar Cells, Solar RRL 9, 2400669, 2025. 

(5) https://www.ines-solaire.org/en/news/a-major-breakthrough-for-photovoltaic-technology-in-space/.

Key words: Space photovoltaics, Silicon solar cells, Irradiations, Self-healing 

Requirements: 

• Master II or engineering School (equivalence Master II): Photovoltaics, Physics, Materials Chemistry / Engineering, Semiconductor / Electronics, polymers, Nanotechnologies, etc. 
• Hands-on experience in thin-film and/or solar cell & module processing in silicon PV, Knowledge of material ageing, knowledge of space science/technology 
• Excellent analytical mind, communication and organization skills 
• Motivation & Team spirit 

CEA / LITEN / DTS 

INES (Solar Energy National Institute) - Savoie Technolac BP332 - 50 avenue du Lac Léman- 73377 Le Bourget du lac 

and CNES 18 Avenue Edouard Belin, 31400 Toulouse

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For more Information about the topics and the co-financial partner (found by the lab!); contact Directeur de thèse - sebastien.dubois@cea.fr

or CEA: Romain Cariou -  romain.cariou@cea.fr

or CNES: Matthieu Fongral - Matthieu.Fongral@cnes.fr

Then, prepare a resume, a recent transcript and a reference letter from your M2 supervisor/ engineering school director and you will be ready to apply online before March 13th, 2026 Midnight Paris time!

- Master II or engineering School (equivalence Master II): Photovoltaics, Physics, Materials Chemistry / Engineering, Semiconductor / Electronics, polymers, Nanotechnologies, etc.

- Hands-on experience in thin-film and/or solar cell & module processing in silicon PV, Knowledge of material ageing, knowledge of space science/technology

- Excellent analytical mind, communication and organization skills

- Motivation & Team spirit17