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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 7: Perovskites - organized by Eva M. Herzig (University of Bayreuth, Bayreuth)
CPP 7.10: Talk
Tuesday, March 23, 2021, 14:40–15:00, CPPa
The tetragonal to orthorhombic crystal phase transition in MAPI studied by time-resolved photoluminescence microscopy — •Alexander Biewald1, Nadja Giesbrecht1, Richard Ciesielski1, Thomas Bein1, Pablo Docampo2, and Achim Hartschuh1 — 1LMU München, Butenandtstr. 11, 81377 Munich, GER — 2Newcastle University, Newcastle upon Tyne, UK
Perovskite-based thin-film solar cells today reach power conversion efficiencies of more than 22% [1]. Methylammonium lead iodide (MAPI) is prototypical for this material class of hybrid halide perovskite semiconductors and at the focal point of interest for a growing community in research and engineering. We investigated the diffusion properties for the orthorhombic and tetragonal phase using time-resolved photoluminescence (PL) microscopy before [2]. Now we focus on the PL dynamics at the phase transition. First, the phase transition is observed in temperature dependent PL spectra, which show the correlated decrease and rise of two spectrally distinct bands. This indicates the coexistence of both phases in a limited temperature range. Second, at the phase transition, which is found to vary between grains, diffusive transport suddenly stops and only reappears upon further cooling or heating, respectively. Our spatio-temporal studies provide detailed microscopic insights into the phase transition and its influence on the carrier dynamics in large crystal MAPI thin films.
[1] M.A.Green et al.,Prog.Photovolt:Res.Appl.,26,427-436,2018
[2] A. Biewald et al.,ACS Appl.Mat.&Interfaces,11,20838-20844,2019