"On the way of stabilizing perovskite material: A fundamental study via Scanning Tunneling Microscopy and Photoelectron Spectroscopy"
Who: Jeremy Hieulle, Nanoimaging Group
Place: nanoGUNE seminar room, Tolosa Hiribidea 76, Donostia - San Sebastian
Date: Monday, 11 May 2020, 11:00
In an effort to limit the current spread of COVID-19, all seminars are canceled beginning Thursday March 12th until further notice
On the way of stabilizing perovskite material: A fundamental study via Scanning Tunneling Microscopy and Photoelectron Spectroscopy
1Energy Materials and Surface Sciences Unit (EMSS), Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1 Tancha, Onna-son, Okinawa 904-0495, Japan.
Organic-inorganic perovskite solar cells are currently under the spotlight. Despite numerous advantages, their poor stability hinders commercialization of perovskite-based devices. To increase perovskite stability various strategies have been envisaged . Mixing different halides (I, Br, Cl) has been shown both experimentally and theoretically to have a strong impact on the device performance and stability [2-5]. However, the stabilizing effect of the halides critically depends on their distribution in the mixed compound, a topic that is currently under intense debate [6-8]. A fundamental understanding remains largely elusive regarding the correlation between the structure of the mixed-perovskites and their electronic properties at the atomic level.
In this work, combining scanning tunneling microscopy (STM), density functional theory (DFT) and UV/X-ray photoelectron spectroscopy (UPS/XPS), we reveal the exact location of I and Cl anions in the mixed CH3NH3PbBr3-yIy and CH3NH3PbBr3-zClz perovskite lattices. Additionally, we demonstrate the impact of halide-incorporation on the material electronic properties and stability. Furthermore, we determine the ideal Cl-incorporation ratio for stability increase without detrimental bandgap modification. The increased material stability induced by chlorine incorporation is verified by performing photoelectron spectroscopy on a device architecture. Our findings provide an important direction for the fabrication of stable perovskite devices.
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