Red Photoluminescence from Bi³⁺and the Influence of the Oxygen-Vacancy Perturbation in ScVO₄: A Combined Experimental and Theoretical Study

Abstract

We report on a red-emitting ScVO4:Bi3+ phosphor which does not show excitation at energies below 2.88 eV (430 nm). X-ray diffraction, time-resolved, and quantitative photoluminescence (PL) spectroscopy were employed to characterize relations between crystal structure and luminescence properties of the material. Results show that incorporation of Bi3+ renders the blue photoemission of blank ScVO4 to red. Dynamic luminescence analysis between 10 and 300 K reveals a complicated dependence of energy transfer from VO43– groups to Bi3+ ions and population redistribution of 3P1 and 3P0 of Bi3+ on temperature. This reflects in distinct changes in the luminescence decay functions. That is, a dramatic decrease of Bi3+ luminescence lifetime occurs from hundreds to only several microseconds. Density functional theory is employed to reveal how the unusual red Bi3+ luminescence comes, and results indicate that the perturbation of oxygen vacancies which is generated readily when bismuth precipitates into ScVO4 is the reason for the experimental observation, although the vacancies themselves do not show photoluminescence. Upon excitations at 330 and 380 nm, internal quantum efficiencies can be up to ∼56% and ∼47%, respectively, implying the potential application of the red phosphor in warm-white-light-emitting diodes. As a proof of concept, an exemplary device was developed by combining the present phosphor with an ultraviolet-light-emitting diode and a commercial phosphor (Ba, Eu)MgAl10O17:Mn. We obtain a color rendering index (CRI) of >90 and a color temperature of ∼4306 K at chromaticity (0.3744, 0.3991).