Hypergap Optical Materials (Adv. Mater. 5/2026)

Hypergap Optical Materials In the Research Article by Ling Lu and co-workers (DOI: 10.1002/adma.202512769), hypergap materials, transparent above the bandgap, are introduced with optical properties unattainable in bandgap insulators, including negative permittivity, anomalous-dispersion phase matching, and negative group-velocity dispersion. High-throughput density-functional-theory searches identify over 200 candidates, and one crystal is experimentally verified, pointing to broad opportunities for plasmonics, nonlinear optics, and ultrafast optics.