Electronic structure and luminescence characteristics of rare earth free self-activated Ca2Sb2O7 blue emitting phosphor

Over the past few years, extensive research has been focused on the development of rare-earth-free phosphors to achieve energy-efficient and cost-effective WLEDs with high luminous efficiencies for solid-state lighting applications. Herein, we report a novel rare-earth-free self-activated blue phosphor Ca₂Sb₂O₇, synthesized by solid-state reaction method. The electronic structure and bandgap of the material were determined by the density functional theory (DFT + U) method using Perdew-Burke-Ernzerhof (PBE) exchange-correlation functional. The prepared phosphor could be effectively excited in the range 280–370 nm resulting in a broad blue emission band, owing to the Sb⁵⁺ → O²⁻ transition in the (SbO₆)^7- group. The CIE chromaticity coordinates were found to be (0.144, 0.097) indicating intense blue emission with high color purity of 89%. Also, the prepared phosphor has good thermal stability and an internal quantum efficiency of 24%. All these results indicate that self-activated Ca₂Sb₂O₇ could be a potential blue phosphor for lighting and display devices.