Scientific direction Development of key enabling technologies
Transfer of knowledge to industry

PhD : selection by topics

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Improvement and understanding of the performance of silicon cell-based solar generators in harsh environments

Département des Technologies Solaires (LITEN)

Laboratoire Photovoltaïque à Concentration

01-09-2020

SL-DRT-20-1061

philippe.voarino@cea.fr

Solar energy for energy transition (.pdf)

The thesis will be carried out at the interface of several laboratories of the Department of Solar Technologies (DTS) of the CEA located in Le Bourget du Lac on the campus of the National Institute for Solar Energy (INES). The objective of this thesis is to improve the resistance to environmental conditions (radiation, e/H+, UV, thermal cycling) of space solar generators based on silicon solar cells, and to better understand the degradation mechanisms of cells/materials associated. By finely controlling the manufacturing of cells (doping, impurity, architecture, etc.) and modules (materials, thickness, architecture, optical trapping, etc.), it is possible to improve the performance of silicon modules at the end of their lifetime while maintaining a competitive price (?/W), 1 to 3 orders of magnitude lower than space III-V modules.

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Modeling the energy consumption flexibility on several spatial and temporal scales

Département des Technologies Solaires (LITEN)

Laboratoire Systèmes Electriques Intelligents

01-10-2020

SL-DRT-20-1068

xavier.lepivert@cea.fr

Energy efficiency for smart buildings, electrical mobility and industrial processes (.pdf)

In a context of massive integration of non-dispatchable renewable production (wind and photovoltaic), the fullfilment of « production = consumption » will imply in the future to act more and more on the second term of this equality. Many questions arise about the real potential of consumption flexibility in a smartgrid, and this depending on the geographic level and also the time range of activation. The management of flexibilities as well as their valuation, will require various models, different depending on the markets (ancillary services, SPOT, intraday, balancing market) and the geographic level considered (house, building, district, city). The thesis will focus on developing: - Electrical consumption and flexibilities modelling - Learning algorithms / parameterization of these models. These will be oriented ?big data?. - Methodologies for getting one model from another To carry out this work, we will use existing simulation tools for the finest spatial scales as well as a consumption measurement database (« Linky » smart metering).

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Scalable and Precise Static Analysis of Memory for Low-Level Languages

Département Ingénierie Logiciels et Systèmes (LIST)

Laboratoire pour la Sûreté du Logiciel

01-10-2020

SL-DRT-20-1088

matthieu.lemerre@cea.fr

Cyber security : hardware and sofware (.pdf)

The goal of the thesis is to develop an automated static analysis (based on abstract interpretation) to verify absence of memory errors in compiled, low-level languages (C, C++, Assembly, Rust). This issue is very important for cybersecurity since most of the software-related security issues come from memory safety (buffer overflows, use-after-free, wrong type punning). The three issues when designing such an automated static analysis is to keep the verification effort low, to handle large and complex systems, and to be precise enough so that the analysis does not report a large amount of false alarms. We draw on the success of a new method using abstract domains parameterized by type invariants, which allowed in particular to fully automatically prove memory safety of an existing industrial microkernel from its machine code, using only 58 lines of annotations, and seek to extend this analysis to larger systems. In particular, the analyzer should be extended to improve scalability (using compositional analysis), to improve precision (using separation logic and SMT/formula-based abstract domains), and to further reduce the amount of annotations (using automatic inference of more precise type invariants).

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Development and characterization of advanced tunnel/recombination layers for 2T and 3T tandem integration

Département des Technologies Solaires (LITEN)

Laboratoire HETerojonction

01-10-2020

SL-DRT-20-1092

delfina.munoz@cea.fr

Emerging materials and processes for nanotechnologies and microelectronics (.pdf)

Today, single junction silicon technology dominates the photovoltaic market, with more than 90 % of market share. However, the power conversion efficiency of silicon solar cells, with a reported record at 26.7 %, has neared its theoretical limit (29 %). To reduce thermalization losses and push efficiency further, silicon cells have been coupled to higher band gap semi-conductors to form tandem cells. Coupling silicon to perovskites appears as a particularly promising solution since perovskites show high performance (25.2 % power conversion efficiency has been reached in a few years), band-gap and thickness tunability and processing versatility. Therefore, silicon/perovskite tandems have the potential to become a high-efficiency technology in the future of photovoltaics. Since 2015, several demonstrations have already been published, either in 2-terminal configuration (2T, both cells connected in series) or in 4-terminal architecture (4T, cells stacking), with record efficiencies above 29 % today. One of the main challenges is the junction between the two sub-cells, which must ensure electrical behavior of charge passage without loss by recombination or optics. Currently transparent conductive oxides are the most used, but they have significant parasitic absorption with associated losses. In this thesis, we aim to develop new materials for the interface layer of a tandem perovskite / heterojunction cell with adaptation of optical index by different techniques and with the two possible configurations, in tunnel junction or in recombination and then characterize electrically, optically and morphologically. In addition, the electrical and optical materials simulation will optimize the complete cell in the different configurations. Finally, stability and integration studies will be done on the most promising junctions.

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Human-in-the-Loop Learning and Adaptation under Uncertain and Unpredictable Situations in AI-based Autonomous Systems

Département Ingénierie Logiciels et Systèmes (LIST)

Labo.conception des systèmes embarqués et autonomes

01-10-2020

SL-DRT-20-1108

huascar.espinoza@cea.fr

Artificial intelligence & Data intelligence (.pdf)

Autonomous systems are evolving towards self-adaptive systems, being boosted by Artificial Intelligence (AI) techniques such as Machine/Deep Learning (M/DL). The emergence of autonomy means that software has to operate in an open and highly dynamic world, being capable of adapting themselves autonomously at run time to new environment conditions or unpredictable situations. In particular, this thesis aims to explore the combination of the capabilities of humans and algorithms to detect uncertainty regions and avoid dangerous situations in the real world and transfer control between a machine and a human (or to the safest agent). Learning-enabled systems based on deep learning are first trained in simulation environments before deploying them in the real world. While simulators are providing increasingly realistic training environments, there is always a gap between simulation and training, because training data does not capture some feature spaces and the model does not learn about them due to the incompleteness of the simulator to reflect the complexity of the real world. Our goal is to find methods for detecting unknown unknowns by combining simulation training with human input from demonstration data.

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High efficiency photovoltaic modules developement for building applications

Département des Technologies Solaires (LITEN)

Laboratoire Modules Photovoltaïques Silicium

01-10-2020

SL-DRT-20-1116

bertrand.chambion@cea.fr

Solar energy for energy transition (.pdf)

Performance of photovoltaic (PV) modules has not stopped to evolve in recent years to reach higher values at 20%. This is possible by a significant effort focussed on the architecture solar cells through gains in light absorption and better collection of photo-generated charges. In contrast, the module packaging and module structure remain similar as previous module structure. On one hand, these modules have been developed in order to work in a standard outdoor PV farm configuration. On the other hand, optimization and development are carried out under standard conditions where the temperature is set at 25 ° C. For Building Integrated (BIPV) applications, it can dramatically decrease their performance. This is related to the urban environment and local microclimate conditions (temperature, surrounding diffuse radiation), orientation and the tilt of the components. In addition, non-optimized integration conditions has a direct consequence and could increase the module temperature, making the thermal dependence on yield (estimated at -0.4% per degree) much more sensitive than in standard application. In addition, BIPV poses other issues related to the architectural aspects of the building: The quality of materials and their colours must match the environment, especially for old buildings. The purpose of this thesis project is to develop integrated PV modules prototypes, optimized for BIPV application, in accordance to the following steps: - State of the art on BIPV applications, materials, light management, thermal and thermomechanical modelling tools - Multi-scale modelling (cell, module, building, town) to understand the PV system thermal behaviour and performances consequences. - PV modules prototypes definition and realization on CEA INES Lab. - Outdoor ageing test and performances monitoring, comparison to standard PV solutions

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