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

We report on a red-emitting ScVO 4:Bi 3+ 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 Bi 3+ renders the blue photoemission of blank ScVO 4 to red. Dynamic luminescence analysis between 10 and 300 K reveals a complicated dependence of energy transfer from VO 4 3– groups to Bi 3+ ions and population redistribution of 3 P 1 and 3 P 0 of Bi 3+ on temperature. This reflects in distinct changes in the luminescence decay functions. That is, a dramatic decrease of Bi 3+ luminescence lifetime occurs from hundreds to only several microseconds. Density functional theory is employed to reveal how the unusual red Bi 3+ luminescence comes, and results indicate that the perturbation of oxygen vacancies which is generated readily when bismuth precipitates into ScVO 4 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)MgAl 10 O 17:Mn. We obtain a color rendering index (CRI) of >90 and a color temperature of ∼4306 K at chromaticity (0.3744, 0.3991).