Pre-perovskite nanofiber: A new direct-band gap semiconductor with green and near infrared photoluminescence

Perovskite-related oxides exhibiting fascinating electric and magnetic properties are important functional materials. We report, for the first time, that pre-perovskite (PP) PbTiO3, characterized by one-dimensional (1D) TiO6 octahedron columns, has a direct-band structure with a gap of 3.20 eV. The faceted single-crystal nanofibers of PP-PbTiO3 demonstrate strong green and near infrared (NIR) photoluminescence (PL) emission at room temperature, which are intrinsic and subjected to quasi-1D crystal structure and electronic band structure. These nanofibers serving as new direct band-gap semiconductors may find applications in novel optical and optoelectronic devices.