Multicolor and warm white luminescence from Dy3+/Eu3+ co-activated glasses for indoor and solid-state lighting applications

Abstract

Multicolor emitting Dy3+/Eu3+ coactivated lithium zinc borate (LZB) glasses were prepared by the melt-quenching method and their structural, vibrational, morphological, and luminescence properties were investigated. Dy3+ glasses exhibited blue, yellow, and red photoluminescence (PL) bands at 481 nm (4F9/2 → 6H15/2), 576 nm (4F9/2 → 6H13/2), and 665 nm (4F9/2 → 6H11/2) under 386 nm excitation. Eu3+ glasses exhibited strong orange and reddish-orange emissions at 589 nm (5D0→7F1) and 612 nm (5D0→7F2) at 393 nm of excitation. 0.5 mol% Dy3+ is codoped with various Eu3+ concentrations and the energy transfer mechanism is analyzed from the spectral overlay of Dy3+ emission and Eu3+ absorption, Dy3+/Eu3+ PL, and decay profiles as well as from energy transfer parameters. Dy3+/Eu3+ codoped glasses stimulated under different excitation wavelengths of Dy3+ (349, 363, and 386 nm) displayed a decline in the intensity of Dy3+ PL bands and a simultaneous rise in Eu3+ PL bands, demonstrating efficient energy transfer from Dy3+: 4F9/2 → Eu3+: 5D0 due to dipole-dipole interaction. The energy transfer process is supported by a decrement in the lifetimes of Dy3+ when co-doped with Eu3+ compared with singly doped Dy3+ones. The color coordinates and corresponding color temperatures were shifted from neutral to a warm white light region depending on the Eu3+ concentration. The aforementioned results demonstrate the importance of the near-ultraviolet-driven LZB: Dy3+/Eu3+ glasses for their potential application in warm white light and multicolor emitting devices.