Influence of surrounding medium on photoluminescence and phase behavior of two-dimensional lead iodide perovskites

Krittin Poottafai

Tao Yuwen

Charles J. Hages

Daniel R. Talham

University of Florida

Two-dimensional hybrid lead iodide perovskites have become a major point of attention for many researchers due to their excellent optoelectronic properties. For most nanoparticles, the large surface to volume ratio allows the changes at particle surfaces to affect the overall physical and chemical properties of the particle. In the case of 2D hybrid lead iodide perovskites, the change at particle surfaces can stem from their interaction with suspending solvent. The chemical interaction between solvent molecules and surface organic layer can change particle surface energy and surface tension(stress), thereby changing the effective pressure on the particle surface. This pressure change can lead to changes in physical properties and average crystal structure of perovskite nanoparticles. Another interaction found in suspended 2D nanoparticles is solvent intercalation. By inserting solvent molecules in between each inorganic layer, the average structure, electron density, chemical properties, and physical properties of the particles can be changed. In this work, we study the effects of organic suspending solvent on phase transition temperature, average crystal structure, and photoluminescence wavelength of [C₉H₁₉NH₃]₂PbI₄ layered perovskite and others in the same family. By varying the organic solvent and alkyl chain length of the lead iodide perovskite nanoparticles, we get more insight into the nature of surface interactions and what leads to intercalation in the 2D hybrid lead iodide perovskites family.