Electronic structure and photoluminescence of Dy~(3+) single-doped and Dy~(3+)/Tm~(3+) co-doped NaBi(WO_4)_2 phosphors

摘要

A single-phase white light emitting NaBi(WO4)(2):Dy3+, Tm3+ phosphor has been successfully prepared by conventional high-temperature solid-state method. First-principles calculations were used to investigate the electronic structures of NaBi(WO4)(2). The calculation results show that NaBi(WO4)(2) has an indirect band gap with 3.02 eV. The crystal structure and PL properties of the obtained phosphor are characterized by SEM, powder X-ray and photoluminescence spectra, respectively. The results demonstrate that all as-prepared crystalline in a tetragonal crystal system with a space group of Id. PL results confirmed that the obtained phosphors can be efficiently excited by 365 nm and generated white light emission. Then the energy transfer between Dy3+ and Tm3+ in the host NaBi(WO4)(2) was investigated. Finally, the chromaticity coordinates of preferred NaBi0.91-x(WO4)(2):0.09Dy(3+), 0.11 Tm3+ (0.3319, 0.3395) were close to the standard white light point (0.333, 0.333). All these results reveal that NaBi(WO4)(2):Dy3+/Tm3+ was a potential single phase white light-emitting phosphor candidate for NUV-based w-LEDs.