Postdoc (f/m/d) Photoelectron Spectroscopy for Perovskite Solar Cells

Postdoc (f/m/d) Photoelectron Spectroscopy for Perovskite Solar Cells Reference No.: SE 2025/12 HZB’s department Perovskite Tandem Solar Cells develops metal halide perovskite solar cells and has achieved several world record efficiencies for perovskite-silicon (32.5%) and perovskite-CIGS (24.2%) tandem solar cells in the past years. We use advanced characterization to determine fundamental properties of perovskite and contact layers, as well as their interfaces. This is key to understanding our devices, and for developing novel materials that allow us to further improve their performance. With this opening, we are seeking a highly motivated scientist (postdoc) with experience in photoelectron spectroscopy (PES) and related analytical methods, as well as strong interest in materials research for photovoltaics and renewable energies. Using a recently commissioned integrated UHV tool with state-of-the-art PES analytics (monochromatized XPS, UPS, Near-UV PES) and evaporator/sputter chamber for device-relevant sample sizes, you will shine light on the electronic and chemical properties of state-of-the-art perovskite films, and electron- and hole-selective contact layers as well as passivating and/or protective interlayers. You will leverage the unique capabilities of our home-built constant final state yield photoelectron spectroscopy (CFSYS) [1] to probe band edges and gap states as well as band offsets in heterojunctions, and work with us on various options to make this technique even more powerful. Thus, working closely with a team of ~20 Postdocs, Master and PhD students in our international and multidisciplinary group, you will contribute directly to understanding and further improving our perovskite-based single- and multijunction solar cells. [1] D. Menzel et al., “Revisiting the Determination of the Valence Band Maximum and Defect Formation in Halide Perovskites for Solar Cells: Insights from Highly Sensitive Near–UV Photoemission Spectroscopy,” ACS Appl. Mater. Interfaces, 13, 43540 (2021), doi: Website. Your Tasks You will... * use monochromatized XPS and UPS to elucidate the stoichiometry and electronic properties of perovskite films and functional layers in single- and multijunction solar cells. * characterize valence band and defect state densities, and determine band offsets at heterojunctions using a special near-UV photoelectron spectroscopy (NUPS, CFSYS)1 developed at HZB. * further improve the NUPS and CFSYS modes for highest sensitivity and extended spectral range. * leverage additional characterization methods such as reflection / transmission, ellipsometry electrical conductivity, spectral and time-resolved photoluminescence, XRD, etc. to understand material properties. * collaborate closely with group members to improve our understanding of these films and their functionality in perovskite single-junction and perovskite / silicon tandem solar cells. Your Profile * Completed doctorate in physics, materials science, chemistry or a comparable field of study * In-depth knowledge of the theory, practice and data analysis of photoelectron spectroscopy with X-ray and UV excitation (XPS, UPS) * Strong interest in advanced analytical methods for materials characterization * Knowledge of semiconductor technology and the physics of solar cells * Excellent analytical skills * Excellent communication and organizational skills * Enthusiasm for solar cells, with a drive for deeply understanding their working mechanisms * Team spirit Your Benefits * A unique opportunity to shape the next generation of photovoltaics through informed choices of materials and processes based on in-depth characterization * Advanced analytical laboratories, including the Berlin electron synchrotron BESSY II * State-of-the-art analytical and device processing equipment maintained by experienced engineers * A growing (> 20 people), highly motivated group with a pleasant atmosphere, supportive environment, and regular social activities * Commitment to diversity and sustainability through an inclusive working environment, promotion of diversity sensitivity and implementation of sustainable and climate-neutral methods * Career-enhancing networking opportunities and individual mentoring and support from the HZB Graduate Centre and HZB Postdoc Office * Attractive remuneration through payment according to Public Service Wage Agreement (TVöD Bund) * 30 days holiday/year * Extensive additional benefits, such as company pension plan (VBL), subsidy for public transport (Deutschlandticket Job) and company sports programmes * Good work-life balance through counselling services on family and career and flexible working time models: Flexitime, part-time, hybrid working * And a team that is looking forward to meeting you! Fixed term contract for 24 months. The salary is based on the Collective Agreement for the German Public Service (TVöD-Bund). How to apply We look forward to receiving your application via our application management system by16.05.2025. For reasons of data protection regulations, we are unfortunately unable to consider applications that reach us by any other means (such as email or mail) in the application process. We very much want our workplace to be diverse, and welcome applications from people with different backgrounds. It is our mission to promote equal opportunities and to improve women’s representation in the workforce. We are therefore very interested in receiving applications from women. Where the qualifications are met, we will give preference to people with disabilities. Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Hahn-Meitner-Platz 1, 14109 Berlin www.helmholtz-berlin.de ➜ APPLY HERE! Climate change poses serious challenges to the whole world. At Helmholtz-Zentrum Berlin, we are researching materials for a climate-neutral future. 1200 employees from all over the world are working together at HZB towards this goal. Join us, and help us achieve it! Learn more about HZB on our website . Follow us on our social media channels LinkedIn , X , Instagram , or visit our YouTube channel . CONTACT Dr. Lars Korte +49 30 8062 41351 korte@helmholtz-berlin.de IMPRINT &DATA PROTECTION