Regensburg 2022 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 30: Poster 2
HL 30.28: Poster
Donnerstag, 8. September 2022, 11:00–13:00, P3
Mapping Excitonic and Ionic Dynamics in Lead Halide Perovskite Thin Films — •Yenal Yalcinkaya1, Pascal Rohrbeck1, Emilia Schütz2, Lukas Schmidt-Mende2, and Stefan A.L. Weber1 — 1Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany — 2Department of Physics, University of Konstanz, Universitätsstr. 10, 78464, Germany
Understanding the dynamics of excitons and ions is crucial for improving the lead halide perovskites and related devices. In this study, we fabricated triple cation lead halide perovskite half cells (ITO/SnO2/Perovskite) with small and large grain sizes. We obtained nearly 100 μm large grains by heat treating perovskite films under methylamine gas atmosphere. Since the grain boundaries are known to be the main source of defects and ion migration in lead halide perovskites, a certain change between charge carrier and defect behaviour between these two types of films is expected. Therefore, we utilized Time-resolved Kelvin Probe Force Microscopy (Tr-KPFM) for mapping the recombination of free charge carriers and ion migration in triple cation lead halide perovskite films with varying grain sizes. Mapping these excitonic and ionic components of photovoltage allowed us to map the defects within the perovskite films. Our results showed a significant increase in free electron-hole lifetimes in large grained perovskite films. Furthermore, we demonstrate the ion migration was suppressed by having fewer grain boundaries within the film. Our study shows how grain sizes affect the free charge carrier movements and how we can track these changes on nanoscale via KPFM.