Zero-energy band observation in an interfacial chalcogen-organic network

Structurally-defined molecule-based lattices such as covalent organic or metal-organic networks on substrates, have emerged as highly tunable, modular platforms for two-dimensional band structure engineering. The ability to grow molecule-based lattices on diverse platforms, such as metal dichalcogenides, would further enable band structure tuning and alignment to the Fermi level, which is crucial for the exploration and design of quantum matter. In this work, we study the emergence of a zero-energy band in a triarylamine-based network on semiconducting 1T-TiSe2 at low temperatures, by means of scanning probe microscopy and photoemission spectroscopy, together with density-functional theory. Hybridization between the position-selective nitrogens and selenium p-states results in CN-Se interfacial coordination motifs, leading to a hybrid molecule-semiconductor band at the Fermi level. Our findings introduce chalcogen-organic networks and showcase an approach for the engineering of organic-inorganic quantum matter.