Berlin 2024 – scientific programme

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 4: Perovskite and photovoltaics I (joint session HL/KFM)

KFM 4.2: Talk

Monday, March 18, 2024, 09:45–10:00, EW 203

Optical In-Situ spectroscopy and reactive spin coating for improved control of perovskite thin film fabrication — •Simon Biberger, Maximilian Spies, Konstantin Schötz, Frank-Julian Kahle, Nico Leupold, Ralf Moos, Helen Grüninger, Anna Köhler, and Fabian Panzer — University of Bayreuth, Bayreuth, Germany

Efficient solar cells require a high-quality halide perovskite (HP) film, which is typically achieved through a solution-based solvent engineering spin coating approach. Here, HP crystallization is induced by applying an antisolvent (AS) to the precursor solution film on the spinning substrate after a specific spinning time. The process involves various controllable and uncontrollable parameters that need to be considered. As a result, fabrication recipes (such as spin speed or timing of AS dispensing) are usually developed empirically and vary between labs. Additionally, factors like changes in the atmosphere that are hard to control can introduce substantial variations between and even within batches of devices. In this work we developed a closed-loop feedback system based on our multimodal optical In-Situ spin coater system in combination with a real-time analysis of the optical spectra during spin coating. We monitor the solvent layer thickness as the parameter of interest during the spin coating. When the target level is reached, the HP crystallization is induced by dispensing the AS via a syringe pump. This method compensates for the effects of uncontrolled parameters, like variation in solvent evaporation rate due to atmospheric changes, thus leading to reproducible film quality.

Keywords: Perovskite; In-Situ Spectroscopy; multimodal spectroscopy; precursor chemistry; solution engineering