Firstly, we collect the Ir complex open-source dataset 42 containing 0.84M structures and the COMPAS-2x open-source dataset 43 comprising 0.5 M cata-condensed hetero-polycyclic aromatic molecules. Then, we generate an additional 11M molecular structures using ring fusion and fragment assembly methods (detailed in the Methods section, Figures and). When generating million-level condensed poly(hetero)cyclic aromatic molecules using the ring fusion method, we allow carbon or heteroatoms to be shared by two or three rings (Figure ). This approach makes our database the first to include molecules with multiple resonance structures. Moreover, we also generate millions of fragment-assembly-based molecules by connecting carbon atoms across different conjugated fragments for the first time.