Quasiparticle electronic structure of 2D heterotriangulene-based covalent organic frameworks and their interfaces with Au (111) surface*

As the search for better materials with new functionalities continues, accurate determination of the bandgaps of materials and energy level alignments at interfaces is central to rational materials design. In this work, we employ the first-principles GW approach to accurately determine the quasiparticle electronic structure of a series of 2D carbonyl bridged heterotriangulene-based covalent organic frameworks (COFs) featuring kagome lattice, with their properties ranging from a semi-metal to a wide-gap semiconductor. Moreover, we study the adsorption of these COFs on Au (111) surface and characterize the interfacial energy level alignment. To reduce the computational cost, we apply the dielectric embedding GW approach and show that it leads to close agreement with experiment. In addition to the well-studied gap renormalization of adsorbates, our calculations illustrate how the interfacial dielectric screening effect modulates the structure of the kagome bands, the charge-carrier mobilities of semiconducting COFs, as well as the Fermi velocity of the semi-metallic COF. Our study provides benchmark results for future experimental and computational work and novel insight into materials design.