Description of the thesis topic

The present PhD project is focused on the development and application of in situ methods for understanding the physico-chemical mechanisms responsible for the degradation of photovoltaic (PV) devices' in real life operation. The chemical or electrochemical changes induced by the main ageing stressors in the absorber layers and interfaces of solar cells will be accessed by performing combined multiscale analyses (ranging from 100 nm for ToF-SIMS and Raman spectroscopy up to 1 mm for XPS and cm2 for optical imaging techniques). The effect of harsh conditions (high humidity and temperature, presence of aggressive species) will be in situ accessed using Confocal Raman spectroscopy with optical imaging and Raman microscopy investigations will be made on the samples during cyclic accelerated tests in chambers or in specifically designed in situ cells. The initial steps of degradation will be also investigated by ToF-SIMS and XPS techniques, allowing to access to high-resolution 3D reconstruction of the interfaces and re-distribution of elemental (including H and isotope tracers) and molecular species. Combining in situ chemical (Raman) and physical (photoluminescence, electrical impedance) survey of the system, a correlation between chemical evolution, opto-electronic and electrical properties will be searched in order to approach the degradation mechanisms. The knowledge, accumulated in this work, is necessary for the development of new strategies for both reliable procedures for real life durability evaluation of new materials and new approaches for durability improvement.

Work Context

The PhD work is a part of WP3 (accelerated ageing and in situ methods) of PEPR TASE Minotaure (https://www.pepr-tase.fr/projet/minotaure/ ). The main part of the work will be made between two laboratories: the IRCP Laboratory, known for its expertise in materials degradation, chemical characterization, in situ methods and accelerated ageing to simulate real service conditions (https://www.chimieparistech.psl.eu/recherche/les-laboratoires/ircp/ , supervision of Prof. P. Volovitch) and GEEPS laboratory, completing the study by its expertise in multiscale physical characterization (https://www.geeps.centralesupelec.fr/ , supervision of Dr. J. Alvares). Regular exchanges are also planned in the frame of the project with the PhD students working on the in situ methods to access mechanical and physical aspects of degradation.

The position is located in a sector under the protection of scientific and technical potential (PPST), and therefore requires, in accordance with the regulations, that your arrival is authorized by the competent authority of the MESR.

Constraints and risks

Mobility is necessary: frequent missions between two laboratories in Paris region (public transport) but also possible stay at synchrotron and/or abroad in the 2nd year, multiple meetings and conferences in France and abroad. Multidisciplinarity and international team of the project and environment requires leadership skills, capacity to manage logistic aspects between two laboratories, ability to lead multidisciplinary discussions and to study new domains rapidly as well as good English skills.

Additional Information

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