Structure and tunable broadband near-infrared luminescence of Cr3+ in borophosphate glass

Abstract

In this work, a series of Cr3+ ion-doped borophosphate glasses were prepared by the melt-quenching method. The structure, optical absorption, and near-infrared luminescence properties of the borophosphate glasses were investigated in detail. The results showed that Cr2O3 plays a modifier role in borophosphate glass consisting of borate and phosphate groups. The indirect optical bandgap and Urbach energy were found to vary in the range of 3.293–3.344 eV and 0.290–0.394 eV, respectively. Meanwhile, the Cr3+ ions located in a weak crystal field environment were confirmed by a Dq/B value of less than 2.3. Under the excitation of 440 nm, the as-prepared glasses exhibit broadband near-infrared (NIR) luminescence with an FWHM of about 210 nm and demonstrate a significant spectral red-shift from 858 nm to 894 nm. When the Cr2O3 content is greater than 0.30 mol%, the fluorescence intensity appears obvious concentration quenching. This work illustrates the potential application prospects of Cr3+ ion-doped glass materials as broadband NIR fluorescent devices.