Ultratransparent metaglasses

Glasses are foundational optical materials in photonic systems, yet their performance is fundamentally limited by Fresnel reflections arising from impedance mismatch with free space. Here, we propose ultratransparent metaglasses, i.e., broadband ultrahigh‑transmission optical materials, comprising titanium dioxide meshes embedded in silica, which generate an effective magnetic response to enable broadband impedance matching and restore effective duality symmetry. The metaglass slabs achieve an average normal-incidence transmittance of 0.99 across an ultrabroad spectral range of 460-730 nm and maintain high transmission for incident angles up to 40°, substantially outperforming conventional silica glasses. The operational bandwidth and spectral position are tunable via the mesh geometry. As a proof of concept, we integrate the metaglass as a cover layer in a perovskite solar cell, achieving enhanced photocurrent density while protecting active layers through strong ultraviolet transmission suppression. The metaglass design principle further extends to the infrared regime. Our results establish a general route to impedance-matched, ultratransparent optical materials, with promising applications in photovoltaics and imaging.