Berlin 2024 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 13: Poster I

HL 13.42: Poster

Monday, March 18, 2024, 15:00–18:00, Poster E

Photoelectron spectroscopy and in-situ time-resolved photoluminescence for the characterization of thin film solar cells — •Philine Stötzner, Alexander Stauffenberg, Markus Müller, Torsten Hölscher, Roland Scheer, and Stefan Förster — Martin-Luther Universität Halle-Wittenberg, Institute of Physics, 06120 Halle, Germany

Alkaline doping plays an important role in improving the efficiency of chalcogenide solar cells based on Cu(In,Ga)(Se,S)₂ (CIGS). By X-ray photoelectron spectroscopy (XPS) performed in ultrahigh vacuum (UHV), we identified the segregation of sodium towards the absorber surface after a controlled exposure to light and various gases. It leads to a degradation of uncoated absorbers that persists even after completion of the whole solar cell [1]. The reduction of the charge carrier lifetime has been confirmed by ex-situ time-resolved photoluminescence (TRPL). Here, we present a setup that combines XPS and in-situ TRPL in UHV accompanied by UPS to study the valence band electronic structure. The experimental setup contains a high-pressure gas cell for exposure to ultra-pure gases or air, a controlled illumination, and alkali dispensers. This setup is perfectly suited to trace back chemical surface modifications and changes in the charge carrier mobilities and electronic properties to a distinct environmental stimulus. Thus, it is not limited to CIGS but also for other absorber materials like organo-metal halide perovskites.

[1] T. Hölscher et al., Progress in Photovoltaics 26 (11), (2018)

Keywords: X-ray photoelectron spectroscopy (XPS); time-resolved photoluminescence (TRPL); chalcogenide solar cells (CIGS); organo-metal halide perovskites