Professor Ioannis Spanopoulos (University of South Florida) Seminar

Title: When Pore and Fulle met Semi: A Tale of Material Architectonics Abstract: With the advancement of technology, there is an increasing demand for multifunctional materials that combine optical, electronic, mechanical, and ionic properties. Hybrid metal halide semiconductors (MHS) have emerged as promising candidates for a wide range of optoelectronic applications, including solar cells, light-emitting diodes (LEDs), photodetectors, and lasers. These materials exhibit a unique set of finely tunable properties, providing a versatile platform for addressing limitations in currently available technologies. In particular, introducing controlled porosity could enable their use in previously unexplored applications such as sensing, electrocatalysis, and solid-state batteries, while the assembly of crystalline MHS that integrate the characteristics of both organic and inorganic semiconductors can open new directions in materials engineering. Motivated by these synthetic challenges, we recently developed a general strategy for generating porosity in MHS using molecular cages serving as structure-directing agents and counter-cations. [1-4] The reaction of the [2.2.2] cryptand (DHS) linker with Pb(II) in acidic media gave rise to the first porous 2D metal halide semiconductor with formula (DHS)2Pb5Br14. The corresponding material is stable in water for over three years, while gas and vapor sorption studies revealed that it can selectively and reversibly adsorb H2O and D2O at room temperature (RT). Solid-state NMR measurements and DFT calculations verified the incorporation of H2O and D2O in the organic linker cavities, and shed light on their molecular configuration. The recorded water stability is unparalleled for hybrid metal halide and perovskite materials, while the generation of porosity opens up new pathways toward unexplored applications (e.g., solid-state batteries and the hydrogen evolution reaction (HER)) for this class of hybrid semiconductors. Taking a step f