Function : Intern
Contract : CNRS internship agreement
Starting date: February/march 2024
Duration: 6 months
Workplace: IPVF – 18 boulevard Thomas Gobert, 91120 Palaiseau
Education: Master 2
IPVF is a scientific and technical pole dedicated to the research and development of solar technologies. It permanently hosts its own staff, as well as the employees of its partners and external companies. IPVF aims to become one of the world’s leading centers for research, innovation, and training in the field of energy transition.
IPVF primary objective is to improve the performance and competitiveness of photovoltaic cells and develop breakthrough technologies by relying on four levers:
• Ambitious research program.
• The hosting of more than 200 researchers and their laboratories on its Paris-Saclay site.
• A state-of-the-art technology platform (8,000 m²) open to the photovoltaic industry actors, with more than 100 state-of-the-art equipment units located in clean rooms.
• A training program mainly based on a master’s degree, the supervision of PhD students, and continuing education.
The IPVF was founded in 2013 on the initiative of the French government, EDF, TotalEnergies, Air Liquide, CNRS, Ecole Polytechnique, Horiba and Riber. Bringing together more than 150 researchers, our 8,000 square meter Paris-Saclay platform is a unique platform for all types of deeptech research and innovation.
The IPVF aims to remain:
• A world leader in photovoltaic-related R&D. By federating the best French teams in the field of research, innovation and industrial production, in partnership with major international institutes, particularly in Europe,
• A leader in the development of photovoltaic technology bricks in line with market trends,
• A reference in sending the most promising R&D concepts to the industry.
The understanding of physio-chemical processes at the interface between two functional materials has always been a critically important domain for our advancement of optoelectronic technologies. Today this scientific domain has become indispensable to solve the most critical challenges about the sustainable and secure energy supply of the future. With silicon-based solar cells close to their theoretical limit for the maximum efficiency, we need to explore the toolkit of materials science to make the photovoltaic module of the future. Thus, moving beyond the current state-of-the-art, the newest generation of solar cells are based on novel absorber materials exhibiting a chemical complexity that reaches far beyond the one of silicon and other traditional semiconductor materials.
Controlling surfaces, interfaces, and grain boundaries of metal halide perovskite (MHP)-based solar cells (PSC) has become one of the main handles to achieve stable high-efficiency devices. Besides, the perovskite material itself induces some complexity within this control of the interface formation since it exhibits volatile organic components, mobile ions, and reactive metal halide species (1). Furthermore, since MHPs denote a class of new absorber materials with tunable wide optical band gap, they offer the opportunity to implement advanced concepts like tandem solar cell architectures to increase power conversion efficiency in a scalable and cost-effective manner (2). However, tandem devices feature an even larger complexity and amount of interfaces that put further constraints on the design rule for the films adjacent to the perovskite, resulting in the need to precisely control the interlayers between perovskite and the other functional cell components layer for maximum performance and stability(3).
We aim to investigate the fundamental physical and chemical properties of MHP thin films (including surface termination, reactivity, and electronic structure), as well as their interfaces with adjacent functional thin films. In this endeavor, we are particularly focused on the analysis of chemical reactions at interfaces by photoemission spectroscopy (PES) methods. For instance, we examined the complexity of the chemical and electronic properties of MHPs over light degradation, chemical passivation, oxide deposition, and dependence on the employed oxide substrate.
 P. Schulz et al. Chem. Rev. 2019, 119, 5, 3349-3417; S. Dunfield et al. Cell Rep. Phys. Sci. 2021, 2, 100520
 M. Jost et al. Adv. Energy Mater.2020, 10, 1904102
 J. Christians, P. Schulz et al. Nature Energy 2018, 3, 68-74
We set two major objectives for this internship to unveil the dynamic properties of additional passivation layers, i.e. films for which an additional surface treatment with specifically tailor-made organic molecules to reduce defect densities, on the MHP film: 1). Monitoring the evolution of the surface photovoltage, surface potential and band bending as a function of the molecular passivation on defective MHP surfaces. In addition to the lab-based photoemission and X-ray absorption spectroscopy data, we will thus conduct steady-state and time-resolved PES measurements of pristine and passivated MHP films with additional laser excitation from the core level shifts. In this approach, we will also evaluate the electronic properties from the valence band measurements and track changes to the work function, which could indicate further dipole effects induced by the organic molecule. 2). Evaluating the impact of the passivation on the charge carrier profile in the MHP as a function of various substrates and interlayers. For this purpose, we will explore the chemical and electronic properties of the pristine and passivated MHP layers., on two different substrate layers but also with and without an ultra-thin electrode film which for the first time will allow for an operando analysis with additional biasing option. In this approach, we will collect an exponentially growing amount of spectral data from X-ray and electron spectroscopies to carefully track and evaluate transient changes at various operational conditions that induce stress and trigger potential instabilities within the perovskite layer and at the interface. In the framework of this internship, we hence aim to develop an AI-guided evaluation method linked to physical models to assess and identify minute but ultimately significant changes in the large data sets.
The main task in this internship will thus be to develop appropriate fitting procedures and correlating large datasets to establish a precise model of the dynamic interface properties in perovskite solar cells. The goal of this endeavor is to enhance the reliability of our methodology and accelerate the implementation of novel interlayers into perovskite-based multijunction cells, i.e. in perovskite-silicon or perovskite-perovskite-silicon triple junction tandems.
– Knowledge in semiconductor physics and/or physical chemistry
– Master : Physics / Materials science / Nanotechnology
– Data treatment and analysis, machine learning
– Interest in numerical methods
– Teamwork for a mixed experimental and theoretical research approach
– Open to work in a multidisciplinary environment
– Curiosity to push scientific boundaries
The application can include: cover letter, CV, and potentially references (name, relation to candidate, and e-mail).
Documents to be sent to:
Philip Schulz email@example.com
Jean-Baptiste Puel firstname.lastname@example.org
Feel free to contact us for more information about our offers.