Regensburg 2019 – scientific programme

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AKjDPG: Arbeitskreis junge DPG

AKjDPG 1: PhD Focus Session: Photoluminescence of halide perovskites: What does it tell us and what not? (joint session DS/HL/AKjDPG)

AKjDPG 1.8: Talk

Tuesday, April 2, 2019, 12:30–12:45, H32

Metastable defects in perovskite semiconductors reveal microscopic insight into non-radiative processes — •Marina Gerhard¹, Boris Louis^1,2, Rafael Camacho², Aboma Merdasa³, Alexander Kiligaridis¹, Jun Li¹, Alexander Dobrovolsky¹, Johan Hofkens², and Ivan G. Scheblykin¹ — ¹Division of Chemical Physics and NanoLund, Lund University, Box 124, 22100 Lund, Sweden — ²KU Leuven, Molecular Imaging and Photonics, Celestijnenlaan 200f, Box 2404, 3001 Leuven, Belgium — ³Helmholtz-Zentrum für Materialien und Energie GmbH, Kekulestraße 5, 12489 Berlin, Germany

Metal halide perovskites are an interesting model system for fundamental studies of non-radiative processes due to their photoluminescence (PL) fluctuations on a timescale of milliseconds to seconds, also referred to as 'blinking'. This phenomenon is attributed to the presence of metastable defects, able to switch between a passive (not quenching) and an active (quenching) configuration. Here, we study temperature dependent blinking of methylammonium lead iodide nanocrystals using PL microscopy. Monitoring the behavior of individual defects allows us to understand their concerted contribution to macroscopic quantities, such as the temperature dependent PL quantum yield. We find that both the quenching efficiency and the switching rate of the metastable defects decrease with decreasing temperature. Based on a simple mechanistic picture, we estimate activation barriers for the switching on the order of 200-800 meV. This energy range suggests that the switching mechanism could be related to ion migration.