Title: "Repercussion of Ion Migration on the Operational Stability of Perovskite Solar Cells: Insight from Photoemission Spectroscopy"

Speaker: Dr. Shivam Singh, TU Dresden, Germany

Abstract: Organic-inorganic hybrid perovskite solar cells (PSCs) attract enormous attention in the field of emerging photovoltaics due to their unique opto-electronic properties and unprecedented advances in performance.1 Despite the sky-rocketed efficiency of lead-based PSCs within one-decade, poor operational stability impedes the commercialization of PSCs.2 While it is generally considered that ionic defect states in the perovskite layer such as vacancies, interstitial sites, anti-site substitutions as well as surface and grain boundary defects inevitably lead to the degradation of PSCs, much remains unknown about the fundamental nature of ionic defects and in particular their migration in perovskite materials.3 In my talk, I will present photoemission spectroscopy (PES) perspective on these aspects of lead-halide based PSCs. First approach investigates the impact of buried interface texture on the degree of ion migration in PSCs and correlates with the operational stability of the devices. Second approach investigates the repercussion of photo-induced phase-segregation on the compositional stratification and energetic landscape of mixed-halide perovskites and correlates with the device instability. Both the studies will expand our current understanding of ion migration in PSCs and could help to identify suitable mitigation strategies to improve the operational stability of the devices.

References: 1 Singh, S., et.al. Journal of Physics D: Applied Physics 2020, 53, 503003. 2 Feng, S. P. et al. J. Phys. Mater. 2023, 6, 032501. 3 Li, Z., et al. Energy & Environmental Science 2017, 10,1234-1242.