Abstract
<jats:p>Descriptor-based screening for organic photovoltaics ranks molecules on computed properties such as frontier-orbital energies and synthetic accessibility, but such descriptors do not test whether a highly ranked molecule is a chemically sensible material. We screened 17,458 molecules from the PubChemQC database using PCESAScore—Scharber-model efficiency minus the RDKit synthetic-accessibility score—and examined what the metric actually returns. Seven molecules cross the viability threshold, but three are not organic semiconductors (molecular oxygen, a magnesium carbonate salt, a quinhydrone cocrystal) and three more carry reactive groups (two azides, one nitroso). A transparent chemicalvalidity filter and a reactive-group screen reduce the viable set from seven to four to a single stable candidate. The top-ranked molecule, an azidotriazine, reaches a 36.1% nominal efficiency—above the Scharber model’s single-junction ceiling—from a 0.91 eV gap, and carries a 9.26 D dipole and a negative computed reorganization energy: signatures of an unusable material, not a lead. Across the dataset, heteroatom composition correlates only weakly with orbital energies (|r| ≤ 0.34), so no simple design rule holds. Descriptor-based materials screens require an explicit chemical-validity and stability gate; the gap between the pre-and post-gate viable sets is a result in itself.</jats:p>