Prediction of intrinsic two-dimensional topological insulators in Y₃-/X₃Y₄-tetrahydroxybenzene metal–organic networks

Using high-throughput density functional theory calculations, we investigate 232 honeycomb–Kagome metal–organic networks formed by two types of metal clusters and tetrahydroxybenzene (THB) molecules. Among the metal–organic frameworks (MOFs) formed with THB molecules and tri-metallic nanoclusters (referred to as Y₃-THB), we find that seven structures are intrinsically topologically nontrivial. By introducing post-transition metal atoms (Tl, Pb, and Bi), nine intrinsic organic topological insulator candidates with considerably larger spin–orbit coupling gaps are discovered among the structure family X₃Y₄-THB. Typically, the α-Pb₃ Zn₄-THB structure has a nontrivial gap of 97.5 meV, almost four times larger than its flat bandwidth (22.5 meV), which can be an ideal platform for realizing the fractional quantum Hall effect. This study provides a new avenue for designing two-dimensional (2D) topological MOFs with large topological band gaps.