Investigation of Degradation Modes of PV Modules for Medium Voltage Applications
To reduce energy losses and costs, photovoltaic power plants have seen their voltage levels increase, which should exceed the standard 1500 Vdc to reach up to 3000 Vdc soon. Even higher voltages, up to 9000 V, could offer very significant economic advantages.
The increase in voltage presents major scientific challenges. High voltages result in degradations grouped under the term Potential-Induced Degradation (PID), leading to significant power losses. These degradations can have several origins: a short circuit of the PN junction (PID-s), depolarization of the solar cell passivation layer (PID-p), or corrosion of the metallization (PID-c). The understanding of PID phenomena at medium voltage remains limited, and there is a lack of comprehensive studies on module materials, the interaction between PID and aging, and the behavior of PID in advanced cell technologies.
The proposed thesis aims to identify the material properties necessary for PV modules to withstand high voltages, combining experimental and simulation approaches.
The doctoral student will need to characterize PV materials (glass, encapsulants) under voltages up to 9000 V, evaluate the impact of aging on the properties of these materials, study the influence of environmental conditions on PID, model the electric field distribution in PV modules, and develop PID mitigation strategies. This research will be conducted in collaboration between G2Elab and CEA, combining expertise in material characterization under medium voltage and photovoltaic module manufacturing.
Growth of Inorganic Halide Perovskite 2D/3D Heterostructures via Pulsed Laser Deposition (PLD) for Optoelectronics and Photovoltaics
Halide perovskites (HPs) have demonstrated exceptional potential in photovoltaics (PV), achieving record efficiencies (35% in silicon-based tandem cells). However, their limited stability (degradation under humidity, heat, or light) and scalability challenges (efficiency loss at large scale) hinder industrial adoption. Concurrently, in microLED applications, HPs are emerging as a promising alternative to quantum dots (QDs) for color conversion layers, thanks to their high spectral purity and superior absorption. Yet, their efficiency and stability still require optimization to compete with existing solutions.
This project proposes an innovative approach: fabricating inorganic 2D perovskites and 2D/3D heterostructures via pulsed laser deposition (PLD), a scalable and unexplored method for perovskites. 2D perovskites, due to their quantum confinement, exhibit high exciton binding energy, making them ideal for LEDs and lasers, while 2D/3D heterostructures enhance stability and reduce non-radiative recombination.
The thesis objectives are:
1. Synthesis of inorganic 2D perovskites (lead-free and lead-based) via PLD and advanced material characterization (crystallinity, luminescence, absorption, bandgap, stability).
2. Fabrication of 2D/3D heterostructures to achieve defect passivation in 3D layers, with advanced characterization (photoluminescence yield, carrier lifetime, interface passivation).
3. Application in PV and microLEDs: evaluating potential for tandem solar cells and color conversion layers.
The results aim to demonstrate that PLD can overcome current limitations (stability, large-scale production) while maintaining competitive optoelectronic performance. This work aligns with global efforts where perovskites could drive significant advancements in PV and microdisplays