D2h-Symmetric Tetratellurium Clusters in Silicate Glass as a Broadband NIR Light Source for Spectroscopy Applications

Broadband near-infrared (NIR) light sources present attractive opportunities for potential applications in high-capacity telecommunication, temperature sensing, energy conversion, and NIR spectroscopy. While significant effort has been spent on materials doped with rare-earth and transition-metal ions, the achievement of these materials with ultrabroadband NIR emission and desired wavelength region remains a long-standing challenge, especially operating in the spectral region between 700 and 1300 nm. Here, such emission is developed in tellurium (Te) cluster-doped silicate glass for the first time. Furthermore, the mechanism of the NIR luminescence due to D2h-symmetric tetratellurium (Te4) clusters is identified by density functional theory (DFT) calculations. For intense luminescence, a model for the generation and stabilization of Te clusters by tailoring topological cages via adjustment of the Na2O and Al2O3 contents and by optimizing the content of the dopant is proposed. Various stable Te clusters embedded into glass exhibit intense visible (Vis) to NIR broadband luminescence (400-1300 nm) with a spectral gap of 900 nm. In a demonstration experiment, a light-emitting diode (LED) device is fabricated from Te cluster-doped glass. This study opens a new opportunity for Te cluster-doped glass as a broadband NIR light source for spectroscopy applications.