Synthesis and photoluminescence of Mn4+ in M4Al14O25 (M = Sr or Mg) compounds as red-light phosphors for white LED

Abstract

Red-light-emitting phosphors Mn4+-doped M4Al14O25 (M = Sr or Mg) were synthesized by solid-state reaction at 1400 °C in air, and their luminescent properties were initially investigated for their applications in warm white-light-diodes (W-LEDs). The excitation spectra of Mn4+-doped M4Al14O25 (M = Sr or Mg) showed that those phosphors were efficiently excited by near ultraviolet (UV) or blue LED chips, and those phosphors exhibited deep red emission band around 650 nm arising from the spin-forbidden 2E → 4A2 transition of Mn4+. The energy transfer mechanism in Mn4+-doped Mg4Al14O25 phosphor was found to be the electric dipole-dipole interaction and the critical distance of energy transfer between the Mn4+ ions was obtained to be about 1.384 nm. The Commission International de L’Eclairage (CIE) chromaticity coordinates of 0.5at.% Mn4+-doped Mg4Al14O25 were (0.631, 0.252). The temperature-dependent luminescence indicated Mn4+-doped M4Al14O25 phosphor was poor thermal-stable. Further work related to improve its thermal stability need be executed for Mn4+-doped M4Al14O25 (M = Sr or Mg) as a promising candidate of red-component for warm W-LEDs.