Energy transfer study in GdVO4: Bi3+, Yb3+ obtained by microwave-assisted hydrothermal method

Abstract

Influence of dopants on the structure, morphology and luminescence properties, and in particular the energy transfer mechanism of GdVO4 co-doped with Bi3+ and Yb3+ ions is discussed. Submicro- and microcrystals were prepared by the microwave-assisted hydrothermal method. Phase purity, size and structure of obtained samples were characterized by the X-ray powder diffraction and the transmission electron microscopy. Luminescence properties were investigated by analyzing photoluminescence and excitation spectra and decay time curves. Intense yellow-green luminescence from Bi3+ ions in the range of 400–800 nm and the near-infrared emission from Yb3+ ions about 1000 nm upon an indirect excitation via the (O2−–V5+) charge transfer state at 266 nm and via the (Bi3+–V5+) charge transfer state at 330 nm was recorded. No concentration quenching effect was observed in the samples doped with up to 7 mol% of Yb3+ ions. The near-ultraviolet sensitized near-infrared emission has been explained by the energy transfer from the GdVO4 host and Bi3+ ions to Yb3+ ions. The energy transfer processes between the host and dopants ions have been characterized in detail. The impact of phonon-assisted processes on the near infrared Yb3+ emission has been investigated. The obtained spectroscopic characteristics prove that GdVO4 co-doped with Bi3+ and Yb3+ ions is a promising candidate for use as the phosphor in luminescent concentrators in photovoltaic applications, which can increase the efficiency of silicon-based solar cells.