Structure and luminescence of a high-efficient blue-red-emitting Na2BaMg(PO4)2: Eu2+, Mn2+ phosphor for plant growth LEDs

Abstract

New dual-emitting phosphor Na2BaMg(PO4)2: Eu2+, Mn2+ is prepared via conventional sintering method. The structural and luminescent properties of as-synthesized phosphor were systematically studied by experimental characterization and theoretical calculation. Utilizing the Eu2+→Mn2+ energy transfer, this phosphor exhibits efficient double-band emissions at 415 and 620 nm, which has a good match with the absorption spectra of chlorophyll A/B and phytochrome in plants. The energy transfer mechanism had been investigated through emission intensity and decay lifetime variation using Reisfeld's approximation method. Na2BaMg(PO4)2: Eu2+, Mn2+ shows promising properties like good thermal stability (75% emission intensity maintenance at 200 °C) and high quantum efficiency (QE > 80%). A prototype LED was fabricated using optimized phosphor and NUV chip, which exhibits two distinct emission peaks modulating an optimum action spectrum for plant absorption. All results indicate that Na2BaMg(PO4)2: Eu2+, Mn2+ is of great potential as converted component for plant growth LEDs.