Function:              PhD student

Contract:              Contrat doctoral de droit privé

Starting date:      October 2026

Duration:              36 months

Workplace:           IPVF – 18 bd Thomas Gobert, 91120 Palaiseau (France)

Education:            Master of science in applied or condensed matter physics, materials science, electrical engineering or equivalent.

Ref.:                         PR-C-M-2-D

IPVF – Institut Photovoltaïque d’Île-de-France

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.

CONTEXT

The development of PV is, in France as everywhere, a booming sector. This PhD offer will take place in the context of Joint Research Program of IPVF, a key actor in research and industrialization of PV in France. The project will be in the ICARE (Improving CharActerization and REliability) thematic of Assessment activities at IPVF. More specifically, the PhD student will join IPVF team of characterisation and modelling, a dynamic and multidisciplinary team of IPVF, and have academic supervision as well. The PhD student will also have academic supervision with part of his/her activities in IPVF, and part at GeePs, as a partner lab nearby.

Perovskite-silicon tandem solar cells have emerged as a novel class of photovoltaic devices that enables us to surpass the Shockley Queisser single-junction efficiency limit. However, understanding the mechanisms governing charge extraction and selectivity at contact interfaces remains one of the most fundamental challenges for advancing perovskite solar cell (PSC) technologies.

While halide perovskites have demonstrated outstanding optoelectronic properties, their integration into stable and efficient devices depends critically on the choice and optimization of contact layers. The subtle interplay between ionic mobility, defect states, and dipolar effects at the perovskite/contact interface determines the overall charge selectivity and strongly impacts the open-circuit voltage and long-term reliability of PSCs.

To gain deeper insight into these interfacial phenomena, we propose to move beyond the conventional vertical device geometry and employ lateral heterojunction (LHJ) architectures based on perovskite thin films with spatially separated contact materials. In this geometry, the perovskite is deposited directly on top of a coplanar configuration of different contact layers, forming a junction that allows the local probing of the potential landscape without the convolution of vertical transport and layer stacking effects. Such an approach provides a powerful proxy to model and predict contact selectivity and charge extraction behavior in the standard vertical device configuration.

To reach these goals, we will deploy an advanced multimodal advanced characterization approach coupled to a dedicated modelling effort. Modelling helps to (i) better understand the impact of various physical parameters on cell performance, (ii) develop and optimize various types of cells without having to systematically use experimental processes that might be costly, (iii) evaluate the potential of new structures and their maximum theoretical efficiency.

MAIN MISSIONS 

Considering the above-mentioned context, the main missions of this PhD project will be to :

1. Work on the development and optimization of the lateral heterojunction (LHJ) samples.

We have recently developed a specific device architecture which enables to better study the interplay of interfaces between absorber (perovskite) and transport layers (ETL/HTL). The next step is to optimize the device architecture and better apprehend the different nanofabrication steps in order to deliver high-quality lateral heterojunction devices. Then, lateral heterostructure samples combining state-of the-art electron- and hole-selective contact materials on benchmark perovskite absorbers will be fabricated.

2. Characterize the LHJ devices using advanced characterization tools.

Advanced nanoscale characterization will be performed on the developed LHJ samples in order to finely study the (electronic) behavior of perovskite-based devices. This will be based in particular on Kelvin Probe Force Microscopy under both dark and illumination conditions, allowing to also extract surface photovoltage maps, but also on laboratory and synchrotron based X-ray and electron spectroscopy mapping to enable a quantitative assessment of the built-in potential and charge selectivity at the contact interfaces. In combination with this activity, we will constantly evaluate the effect of contact layers in the vertical device stack, which are developed in the Impacts program, by regular KP/SPV measurement series.

3. Develop numerical modelling of the device.

The model will be employed to unravel and analyse the data obtained and establish a predictive framework for contact layer optimization in perovskite-based tandem architectures. The results will provide valuable insights into the electronic selectivity mechanisms that govern the efficiency and stability of perovskite solar cells and pave the way for their reliable integration into future multijunction photovoltaic modules

Publications related to this PhD thesis:

Carrier gradients and the role of charge selective contacts in lateral heterojunction all back contact perovskite solar cells