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Biberger, Simon ; Schötz, Konstantin ; Leupold, Nico ; Ramming, Philipp ; Spies, Maximilian ; Moos, Ralf ; Köhler, Anna ; Grüninger, Helen ; Panzer, Fabian:
Using Multimodal In Situ Spectroscopy to Understand the Influence of the Ionic Liquid BMIMBF4 on the Film Formation and Optoelectronic Properties of MAPbI3 Thin Films.
2023
Veranstaltung: 2023 MRS Spring Meeting & Exhibit
, April 10-14, 2023
, San Francisco, California, USA.
(Veranstaltungsbeitrag: Kongress/Konferenz/Symposium/Tagung
,
Vortrag
)
Abstract
Today, metal halide perovskite solar cells are one of the most promising emerging photovoltaic technologies. A key to such highly efficient devices is to realize high-quality perovskite layers, which requires a deep understanding about the perovskite formation and good process control. In-situ experiments have been proven to give important insights into the formation process of the perovskite absorber layer. We use multimodal optical in-situ spectroscopy to further develop an understanding of the thin film formation of the model halide perovskite methylammonium lead iodide MAPbI3 during the one-step processing and the solvent engineering approach. Further, we investigate how the identified formation processes change when we mix a passivating additive, the ionic liquid (IL) BMIMBF4 into the perovskite precursor solution. One-step processing experiments reveal that IL in the precursor solutions does not affect the formation of perovskite–solvent complexes, but higher IL contents delay the perovskite transformation and decrease growth rates. For solvent engineering, the perovskite growth rate decreases with later antisolvent (AS) dripping as the properties of PbI4 2- species in the precursor solutions change during drying. Here, the IL also affects the evolution of the PbI4 2- properties, as the IL cation interacts with the PbI4 2-. This interaction appears to reduce the perovskite crystallite growth rates after initiating perovskite formation by AS dripping. Thus, this work shows the sensitive interconnection between precursor properties, film formation process, and final optoelectronic properties of perovskite thin films and how small amounts of additive can impact this relationship. Further, this work highlights the potential of optical in-situ spectroscopy to facilitate more tailored solution processing strategies in the future.