SKM 2023 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 25: Perovskite and photovoltaics II (joint session HL/CPP)

HL 25.1: Hauptvortrag

Mittwoch, 29. März 2023, 09:30–10:00, JAN 0027

Interfaces in perovskite optoelectronics: role of energy level alignment and interface chemistry — •Selina Olthof — Universität zu Köln, Institut für Physikalische Chemie

Optoelectronic devices, such as perovskite solar cells, are typically multi-layer stacks in which the absorber layer is sandwiched between metal oxide and/or organic transport layers in order to facilitate charge extraction or ensure charge selectivity. As the perovskite absorber layer has been extensively optimized in the past years, the awareness is rising that device efficiency and stability is limited by the interfaces present in the device. However, in perovskite-based devices, the role of this energy level alignment remains to be elusive and rather inconclusive studies can be found in literature, which I will briefly outline. More important for the device seems to be the perovskite composition at the interface which can be significantly influenced by chemical reactions taking place, in particular next to metal oxides. I will summarize our work on a variety of metal oxides in which we use photoelectron spectroscopy to analyze which components are responsible for the strong interface chemistry. We show that the reactivity strongly depends on the choice of perovskite and that different metal oxides show fundamentally different reaction/degradation pathways. Intriguingly, we are able to introduce surface treatments which change the surface defect density and thereby affect the degree of perovskite degradation significantly.