Deep red SrLaGa3O7:Mn4+ for near ultraviolet excitation of white light LEDs

Abstract

Red luminescent phosphor SrLaGa₃O₇:Mn⁴⁺ was prepared by the traditional high-temperature solid-state reaction. The structural characteristics, luminescence properties and the performance of this phosphor were investigated in light-emitting diode devices. Deep red emission peaking at ∼715 nm was observed under the excitation wavelength in the range of 220–550 nm, which is related to the charge transfer band of Mn⁴⁺–O²⁻ and the ⁴A_2g → ⁴T_1g, ⁴A_2g → ²T_2g and ⁴A_2g → ⁴T_2g transitions of Mn⁴⁺. In particular, SrLaGa_3(1−x) O₇:3xMn⁴⁺ exhibits the strongest absorption in the near ultraviolet region (350–410 nm). This feature can well match the emission of current commercial near-ultraviolet chips, and is expected to be used in white LEDs. Moreover, we also conducted a thermal quenching experiment on the SrLaGa₃O₇:Mn⁴⁺ phosphor, and the obtained activation energy was 0.4 eV, indicating that the quenching temperature is (T_50%) 370 K. Finally, the application of the SrLaGa₃O₇:Mn⁴⁺ phosphor in constructing a LED device was explored. At a driving current of 20 mA, the Commission on Illumination (CIE) coordinates of the device are (0.3281, 0.3080), with a high color rendering index (CRI) of 91.9 and a low corresponding color temperature (CCT) of 4315 K. Experimental results show that the phosphor has broad prospects in preparing white LED devices excited by near-ultraviolet light.