SKM 2023 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 7: Poster I

HL 7.36: Poster

Monday, March 27, 2023, 13:00–15:00, P2/EG

Reflection Electron Energy Loss Spectroscopy of Organic and Perovskite Semiconductors — •Seren Dilara Öz and Selina Olthof — Department of Chemistry, University of Cologne, Greinstraße 4-6, 50939 Cologne, Germany

The analysis of fundamental semiconductor properties, such as energy level positions and bandgaps, are important to enhance our understanding of these materials and to further improve their performance in applications. In this context, many spectroscopic tools such as ultraviolet photoelectron spectroscopy or UV-vis measurements are exploited. In this project, we explore the use of reflection electron energy loss spectroscopy (REELS) which is a rarely used technique in order to investigate the surface density of states (DOS) and bandgap of organic and perovskite based semiconductor materials.

This measurement technique records the energy loss due to inelastic electron scattering processes which excites electronic transitions. It presents an intriguing technique to gain insights on the joint valence and conduction band density of states over a wide energy range. Due to the extreme surface sensitivity, the band gap of ultra-thin layers can be accessed.

In this work, we try to understand the observed energy loss spectra in order to establish guidelines to investigate surface properties of semiconductor materials. For that reason, information gathered using REELS are compared to UPS, IPES, and UV-vis measurements. Our results show that the REELS technique can be used as an effective tool to explore surface properties of perovskite and organic semiconductors.