A terbium-sensitized Eu3+-activated deep-red-emitting phosphor for plant growth LED application.

• A novel terbium-sensitized Eu3+-activated phosphor, Ca 2 TbSn 2 Al 3 O 12 :Eu3+, has been designed and synthesized. • The solid-state MAS NMR spectra have been used to confirm the reasonability of the XRD structural refinements. • The far red emission of Eu3+ is extremely dominant, which can well match the absorption spectra of P fr in plants. • Terbium is one of the host composition elements, and thus, highly efficient Tb3+-Eu3+ energy transfer can be realized. • An experimental evidence that proves the existence of terbium bridge energy transfer has been discussed in detail. [Display omitted] Traditional Eu3+-activated inorganic phosphors are habitually used for general lighting and display because they generally emit either intense orange (5D 0 -7F 1) or red (5D 0 -7F 2) light whose wavelength is shorter than 630 nm. However, less known nor focused is that Eu3+ at sites with specific symmetry can intensify its 5D 0 -7F 4 transition, enabling Eu3+ itself to emit deep red light (>700 nm) even stronger than the above orange and red ones. Herein, a novel Eu3+-activated phosphor, Ca 2 TbSn 2 Al 3 O 12 :Eu3+, is developed from the garnet structure. Differing from other Eu3+-activated phosphors, the 5D 0 -7F 4 transition of Eu3+ in the host is dominant and the orange, red and deep red emissions are balanced. Such special features of Eu3+ luminescence mainly meet the need of phytochromes (P FR and P R) in plants. Additionally, bridge style energy transfer from the host composition element Tb3+ to the activator Eu3+ can be observed. It is found the Tb3+-Eu3+ energy transfer here takes through the mechanism of dipole-dipole interaction and the simulation on decay curve of Eu3+ upon Tb3+ excitation, for the first time, confirms the existence of terbium bridge energy transfer. For the Ca 2 Tb 0.60 Sn 2 Al 3 O 12 :0.40Eu3+, the energy transfer efficiency is as high as 94.4% and the emission color is totally red. Thermal quenching studies reveal that the emission intensity of the phosphor at 425 K sustains 80% of its initial intensity at room temperature. By fabricating the phosphor with a 380 nm LED chip, a plant-growth LED device can be obtained. [ABSTRACT FROM AUTHOR]