Energy transfer mechanism and tunable emissions from K3La(VO4)2:Dy3+/Eu3+ phosphors and soft-PDMS-based composite films for multifunctional applications

Novel Dy3+ and Eu3+ ions co-doped K3La(VO4)(2) (KLVO) phosphors were synthesized by a facile citric acid-assisted sol-gel method. The crystal phases of the synthesized phosphor samples were identified by X-ray diffraction pattern after calcination process, which indicated the monoclinic phase patterns with a space group of P2(1)/m(11). The luminescent behaviors of the self-activated KLVO and KLVO:Dy3+ and KLVO:Dy3+/Eu3+ phosphors were studied by the recorded photoluminescence excitation and emission spectra at room temperature. Under ultraviolet (UV) or near-UV excitations, the KLVO:Dy3+ phosphors exhibited characteristic emission properties. More importantly, different low concentrations of Eu3+ ions were co-doped into the optimized KLVO:Dy3+ phosphor to compensate its red component and the color-tunable emissions were noticed with an energy migration mechanism from Dy3+ to Eu3+ ions. Likewise, the thermal properties for the optimized co-doped material system were investigated, showing superior results for the practical application point of view. Furthermore, soft polydimethylsiloxane (s-PDMS)-based films were made for the first time utilizing the KLVO:5 mol% Dy3+/yEu(3+) (y = 0, 0.25, 0.5, 0.75, 1, 2 and 3 mol%) phosphors. Consequently, the obtained s-PDMS-based phosphor composite films demonstrated their suitability for the potential application of luminescent films, solid-state UV lightning devices and flexible display devices in optoelectronic industries. (C) 2019 Elsevier B.V. All rights reserved.