# PhD Position - Data-Driven Development of Stable Wide-Bandgap Perovskite Subcells for Tandem Photovoltaics The "Helmholtz-Institute Erlangen-Nürnberg for Renewable Energies" (HI ERN) is part of Forschungszentrum Jülich and works in close collaboration with the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) and the Helmholtz-Zentrum Berlin (HZB). The research at HI ERN is focused on the areas of innovative materials and processes for hydrogen technologies and photovoltaic energy, therefore covering novel approaches for the conversion and storage of CO2-neutral energy. ## Your Job Wide-bandgap metal-halide perovskites are key absorbers for next-generation multijunction photovoltaics. Their practical use, however, is still limited by compositional instability, phase segregation, interface-related energy losses, and insufficient process reproducibility. Addressing these challenges requires a workflow that connects rapid materials and process exploration with rigorous device and lifetime validation. This position is part of a twin-PhD collaboration between Forschungszentrum Jülich (FZJ) and the French Alternative Energies and Atomic Energy Commission (CEA). The two projects share the goal of developing stable and reliable perovskite-based tandem photovoltaics, while maintaining complementary scientific responsibilities. - **FZJ focus:** automated and data-driven development of reproducible wide-bandgap perovskite absorbers and complete perovskite subcells, including their intrinsic stability, phase behaviour, interfaces, and accelerated ageing. - **CEA focus:** integration of selected candidates into perovskite/silicon tandem cells, device and module fabrication, lifetime testing, and feedback on performance and degradation mechanisms. You will establish a closed-loop workflow from material and process discovery to subcell validation and transfer to tandem devices. Your main tasks will include: - Establish a stable and reproducible p–i–n wide-bandgap perovskite baseline, with the main focus on absorbers in the 1.65–1.70 eV range - Use automated and high-throughput experimental platforms to screen composition, additives, interfaces, passivation strategies, and processing conditions - Apply data-driven and machine-learning methods for multi-objective optimization of efficiency, reproducibility, and operational stability - Study intrinsic material stability, light-induced phase segregation, ion migration, and interface-related energy losses - Fabricate and evaluate complete single-junction and, where relevant, semi-transparent perovskite subcells using PL/PL mapping, XRD, current–voltage measurements, EQE, and accelerated ageing - Transfer promising candidates to CEA for tandem integration and use the resulting performance and lifetime feedback to guide a second optimization cycle at FZJ - Evaluate whether successful stabilization and interface strategies can be transferred to wider-bandgap perovskites (1.75–2.0 eV) for future multijunction concepts ## Your Profile - A Masters degree in materials science, chemistry, physics, chemical engineering, electrical engineering, or a related discipline - Strong motivation for hands-on research in thin-film materials, semiconductor processing, or photovoltaic devices; experience with perovskite cells, optoelectronic characterization, glovebox work, or cleanroom processing is an advantage - Interest in data analysis, automation, design of experiments, or machine learning; prior expertise is welcome but not required if you are motivated to learn - A rigorous and safety-conscious working style, with careful documentation and adherence to shared-facility procedures - Very good command of written and spoken English with extensive vocabulary is required (at least B2 level according to the [CEFR](https://go.fzj.de/languagerequirements)), ideally supported by a certificate confirming the language level - Independent and collaborative working style - Willingness to spend an extended research period in France ## Our Benefits for You - **Team & Environment:** You will work in a motivated team with an international and interdisciplinary focus – at one of the largest research institutions in Europe - **Research & Infrastructure:** You will have access to excellent scientific and technical facilities for your work - **Work-life balance:** We offer flexible working hours to help you balance your professional and personal life. You also have the option of flexible working (in terms of location), which is generally possible after consultation and in line with upcoming tasks and (on-site) appointments - **Annual Leave:** You get 30 days of annual leave - **Knowledge & Development:** Your professional development is important to us – we support you specifically and individually e.g., through training and networking opportunities specifically for doctoral candidates [(JuDocS)](https://go.fzj.de/JuDocs) - **Fair remuneration:** Depending on your qualifications and assigned responsibilities, you will be classified according to pay group 13 (75%) of the TVöD-Bund. All information about the TVöD-Bund collective agreement can be found on the [BMI website](https://go.fzj.de/bmi.tvoed) (pay scale table on page 74 of the PDF download) - **Fixed-term:** The position is limited to 3 years - **Support for international employees:** Our International Advisory Service makes it easier for international employees to get started In addition to exciting tasks and a collegial working environment, we offer you much more: [https://go.fzj.de/benefits](https://go.fzj.de/benefits) We welcome applications from people with diverse backgrounds, e.g. in terms of age, gender, disability, sexual orientation / identity, and social, ethnic and religious origin. A diverse and inclusive working environment with equal opportunities in which everyone can realize their potential is important to us. The following links provide further information on diversity and equal opportunities: [https://go.fzj.de/equality](https://go.fzj.de/equality) and on specific support options for women: [https://go.fzj.de/womens-job-journey](https://go.fzj.de/womens-job-journey) **Place of Employment:** Erlangen **Start Date:**To the next possible date **Salary:** Pay group 13 (75%) TVöD-Bund **Application Deadline:** The position will be advertised until it is successfully filled. **Index number:** 2026D-0685 [Application Process](https://go.fzj.de/ApplicationInformation) [FAQ](https://go.fzj.de/FAQ_eng) [Contact form](mailto:karriere@fz-juelich.de?subject=Query%20about%202026D-0685%20PhD%20Position%20-%20Data-Driven%20Development%20of%20Stable%20Wide-Bandgap%20Perovskite%20Subcells%20for%20Tandem%20Photovoltaics) [Career portal](https://go.fzj.de/Careers) [Forschungszentrum Jülich GmbH](https://www.fz-juelich.de/en) [Legal Notice](https://cs-media.b-ite.com/forschungszentrum-juelich/impressum-recruiting-en.pdf)