Regensburg 2025 – scientific programme

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DS: Fachverband Dünne Schichten

DS 12: Gaede-Jubiläumssitzung

DS 12.1: Invited Talk

Thursday, March 20, 2025, 16:15–16:45, H3

Probing the Electronic Structure of Halide Perovskites — •Selina Olthof — Department of Chemistry, University of Cologne — Chair of Material and Surface Analysis, University of Wuppertal

Halide perovskites are a novel class of thin film semiconductors that have revolutionized the field of photovoltaics, nowadays even surpassing in record efficiency the conventional silicon-based cells. Their remarkable defect tolerance, solution-based processability and tunable band gap make them highly promising for next-generation optoelectronic technologies.

This talk will provide a brief introduction to halide perovskites, highlighting the origins of their exceptional material properties. Next, I will introduce UV photoelectron spectroscopy (UPS) as well as reflection electron energy loss spectroscopy (REELS) as powerful tools to gain deeper insight into device relevant material properties. Specifically, I will discuss our investigations into the valence and conduction band density of states in tin and lead-based 3D perovskites. By combining photoelectron spectroscopy results with density functional theory, we identified the roles of atomic positions, bond hybridization, and lattice distortions in shaping the electronic properties.

Additionally, I will introduce our recent work on reduced-dimensionality perovskites (2D layers), which are gaining attention for their potential to optimize interfaces and enhance solar cell efficiencies. Here, I will present a systematic study using alkyl-based organic cations with varying chain length, which we used to track effects of interlayer spacing on the electronic and optical properties.

Keywords: photoelectron spectroscopy; halide perovskite; semiconductor; thin film; reflection electron energy loss spectroscopy