Colour tunable Ca3Y2Ge3O12: Tb3+, Eu3+ phosphors with high quantum yield for white LED applications

Abstract

A series of Ca3Y2Ge3O12: xTb3+, yEu3+ (CYGO) phosphors were prepared by the high-temperature solid-phase reaction method. The physical phases, luminescence properties, and energy transfer of the samples were systematically analysed and discussed by XRD and fluorescence spectroscopy. Under the excitation at 377 nm, the CYGO: xTb3+ phosphor emits green light, and the concentration quenching point of Tb3+ ions is x = 0.24. The fluorescence intensity of Tb3+ ions decrease with the increase of the concentration of Eu3+ in CYGO: xTb3+, yEu3+ phosphors, the fluorescence intensity of Eu3+ ions increase rapidly, and the luminescence colour changes from green to red with the increasing of the concentration of Tb3+ at a certain concentration of Tb3+, the luminescence colour changes from green to red, confirm the existence of an energy transfer process between Tb3+ and Eu3+. The energy transfer mechanism is quadrupole-quadrupole interaction. The quantum yield is as high as 95.45%. Under the excitation of the UV-LED chip at 370 nm, the LED based on CYGO:0.24 Tb3+, 0.08Eu3+ phosphors have a Ra of 86.7, low CCT of 4917 K and CIE coordinate of (0.3498,0.3789), so the CYGO: xTb3+, yEu3+ phosphors have a potential for application in the field of UV-near-UV white LEDs. has a certain application potential.