Title: Control of Polarization in 2D Hybrid Perovskites

Abstract: The precise control of polarization in solid-state materials holds immense significance across various scientific disciplines, particularly optics and electronics. This control enables tailored manipulation of light-matter interactions, device functionalities, and electronic properties, leading to a host of practical applications. In this presentation, I will showcase our recent discovery of a broadband optical retardation effect in 2D organic-inorganic hybrid perovskite single crystals. We found that this remarkable optical retardation effect can be attributed to the large in-plane birefringence of 2D hybrid perovskites. We suggest that the broadband optical retardation effect arises due to the formation of mosaicity among the stacked inorganic layers, resulting in out-of-plane disorder during the self-assembly process of single crystals in the solution phase. I will discuss the design principles for tuning mosaicity and the robustness of these materials for transformative impacts.

Additionally, I will discuss our observation of optically induced switchable polarization in 2D hybrid perovskites. Through the use of cutting-edge characterization techniques, such as X-ray diffraction scattering measurements under optical excitation, we were able to probe and study the excited-state structural dynamics from these materials. We identified a clear trend of reversible lattice expansion and contraction at various time scales.

Overall, the ability to control polarization in solid-state materials provides a versatile toolkit for advancing a wide range of technologies, enabling innovations that impact communication, imaging, energy harvesting, sensing, and more.

Host: Dali Sun