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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 57: Hybrid Perovskite and Photovoltaics I (joint session CPP/HL)

CPP 57.5: Vortrag

Mittwoch, 18. März 2020, 10:30–10:45, ZEU 260

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