Exploring the Optoelectronic Properties of Calcium Vanadate Semiconductors: A Combined Experimental and DFT Study

Metal vanadates have garnered significant interest owing to their exceptional potential for diverse practical applications., which stem from their unique framework structures, bond strength heterogeneity, and strong O2--V5+ charge transfer bands. However, their electronic and optical properties remain insufficiently explored. In this work, we synthesized three high-purity calcium vanadates compounds (CaV2O6, Ca2V2O7, and Ca3V2O8) and conducted a comprehensive investigation of their optoelectronic properties through first-principles calculations alongside experimental characterizations. The results demonstrate that CaV2O6, Ca2V2O7, and Ca3V2O8 are all indirect bandgap semiconductors, with bandgap values ranging from 2.5 to 3.4 eV. A comparative analysis between DFT and DFT+U calculations reveals that standard DFT is sufficient to accurately describe the lattice parameters and bandgaps of these vanadates. Further luminescence studies show significant photoluminescence and electroluminescence properties within the visible light spectrum. Notably, the luminescence intensity of CaV2O6 exhibits a remarkable tenfold enhancement under a modest pressure of just 0.88 GPa, underscoring its exceptional potential for pressure-tunable optical applications. These findings provide deeper insight into the electronic structure and optical behavior of vanadates, highlighting their potential as strong candidates for applications in phosphor materials and optoelectronic devices.