Two-Dimensional Lead Organic Chalcogenide Materials with Strong Electron-Phonon Coupling

Two-dimensional (2D) metal organic chalcogenides (MOCs) such as silver phenylselenolate (AgSePh) have emerged as a new class of 2D materials due to their unique optical properties. However, these materials typically exhibit large band gaps, and their elemental and structural versatility remains significantly limited. In this work, we synthesize a new family of 2D lead organic chalcogenide (LOC) materials with excellent structural and dimensionality tunability by designing the bonding ability of the organic molecule and the stereochemical activity of the Pb lone pair. The introduction of electron-donating substituents on the benzenethiol ligands results in a series of LOCs that transition from 1D to 2D, featuring reduced band gaps (down to 1.7 eV), and broadband emission. Furthermore, strong electron-phonon coupling is characterized by the presence of coherent optical phonons with long dephasing time, suggesting the low phonon anharmonicity in the LOC materials