(167b) Insight into the Reaction Mechanism of Amine Molecules on the Hybrid Halide Perovskite Surface

The reaction between amines and hybrid halide perovskite has been applied to synthesize different types of perovskite materials, improving their environmental stability and interfacial charge-transporting efficiency. Despite these important applications, we have a poor understanding of the mechanisms and kinetics behind these reactions. Still, we do not understand how the reaction rate and the extent of the reaction (i.e., surface limited or bulk transformation) are affected by related factors, including the steric hindrance force of an amine, its proton affinity, and process parameters. The lack of such fundamental understandings severely limits our ability to apply these reactions to rationally engineer the composition and microstructures of perovskite materials for more stable and more efficient devices. In this regard, we planned to fill up this knowledge gap by using in situ tools to track the progression of the reactions in real-time at realistic conditions. We used in situ Infrared (IR) spectroscopy, quartz crystal microbalance (QCM), and Quadruple Mass Spectrometry (QMS) on a vacuum reactor to study amine-perovskite reactions in real-time at well-controlled practical processing conditions (i.e., reaction temperature, partial pressure of amines, and reaction time). With in situ quartz crystal microbalance and infrared, we showed that the pressure of these molecules has a dramatic effect on their reactions with hybrid perovskites. The composition of hybrid perovskite materials also has a strong effect on their reaction with these molecules. These results will be critical to using these molecules to modify perovskite substrates for applications in solar cells, LEDs, and sensors.