The quest for more efficient photovoltaic panels raises the question of which materials to make up the cells. Nathanaelle Schneider is a researcher at CNRS. Within the IPVF Programme VI, she uses molecular chemistry and materials science to design, develop and provide efficient functional materials.
How do you work on this program? What are your objectives ?
I work within the Programme VI, also called the PROOF program, an acronym for « Photovoltaics Research Outlook On its Futures ». The goal of this program is to push the limits of photovoltaics. “Pushing the limits” in terms of usages, for instance by getting inspired by butterfly wings to develop building-integrated photovoltaics demonstrators. It also aims to push the limits of performances of the cells, reaching ultimate efficiencies or using alternative materials and fabrication methods. This program is designed to address complicated challenges and to work on projects with higher risk factors (risk of success or failure, not from a financial point of view), but with potential high gains.
This programme is divided into five projects. I am the principal investigator of one of them on new functional materials and new processes. Indeed, all photovoltaic devices are composed of various materials, each of them having their own functions. This translates into the need for materials with several requirements and target properties. Moreover, as the materials are integrated in full devices, there are constraints on their synthesis conditions, to avoid any deterioration of the other cell constituents. The goal of this project is to design, elaborate and provide new functional materials. As a chemist, I have to propose solutions.
Atomic Layer Deposition (ALD) is a well suited technique to meet these challenges. In ALD, molecules react on the surface of a substrate to form the material. This allows a fine control of both the thickness and the composition of the films. In addition, its synthesis conditions are gentle compared to other deposition methods. Finally, whatever the shape of the substrate, the material will deposit everywhere in the same way. ALD is therefore well adapted to develop functional materials with specific properties, and using this technique allows the design of new photovoltaic devices.
In practice, this requires expertise and several skills. In particular, along with setting up new processes, tools to monitor and model ALD growth are developed, and materials are characterized in collaboration with the programme IV. The aim is to understand how the molecule reacts on the surface and what functions it gives to the material. Finally, these new materials are integrated in the various devices developed within the IPVF. All these efforts allow us to design new precursor molecules and film compositions.
The benefits are not limited to photovoltaics. These findings can also be applied to optics or microelectronics, where today’s majority of industrial uses of ALD are taking place.
Why did you get involved in this IPVF program?
I got involved in this project because it is a unique opportunity to mobilize different partners, such as CNRS, Total, Air Liquide or Horiba, on a specific topic. Each partner brings its know-how and its own specific knowledge on material preparation and characterization, and on devices. We are already supported, for instance by a CNRS assistant engineer who has become the backbone of the project, and additional people will be specifically hired: an engineer for materials development and two post-doctoral researchers for the development of innovative in-situ methods.
This program requires complementary knowledge on materials, thin film growth, characterization and photovoltaics and is meant to support and be supported by other IPVF specific programs or projects. The challenge of understanding the ALD growth, which is essential to develop new efficient functional materials, is very interesting and allows me to consider several aspects, from molecular chemistry, to surface and materials science, via modeling.
Finally, IPVF have unique facilities and we are one of the few teams working on sulfide materials, which highlights our originality.
When did you start working on R&D Photovoltaics?
I have been a CNRS Research fellow since 2013, trained as a molecular chemist. During my PhD (Heidelberg and Strasbourg universities) or later in Japan (at AIST Research Institute and at Air Liquide R&D laboratory), I worked for other application fields such as asymmetric catalysis or microelectronics. I started applying my research to photovoltaics in 2012 when I took charge of a mission at IRDEP. Chemistry and material science remain the common thread in all of these.
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