Two Ce3+ centers induced broadband emission in Y3Si6N11:Ce3+ yellow phosphor

Abstract

The Y₃Si₆N₁₁:Ce³⁺ yellow phosphor shows a well-known ∼150 nm broad emission band, exhibiting a potential application in UV or blue based white LEDs. We report the observation of two Ce³⁺ emitting centers, the superposition of which forms the broad emission band. One center has a green emission band peaked at 539 nm (Ce1) with the first excitation band at 420 nm. The other has a red emission band peaked at 600 nm (Ce2) with the first excitation band at 485 nm. The two Ce³⁺ centers are assigned to the substitution for two Y sites in Y₃Si₆N₁₁. It was found that the Ce2 emission intensity is continuously enhanced relative to that of Ce1 with an increasing Ce³⁺ concentration, thus leading to a redshift of the broadband. Meanwhile, a more notable fluorescence lifetime shortening of Ce1 compared to Ce2 with an increasing Ce³⁺ concentration was observed. These results suggest the occurrence of energy transfer from Ce1 to Ce2. The temperature-dependent luminescence intensity of Y₃Si₆N₁₁:Ce³⁺ was also studied in the range of 93 to 473 K.