Abstract
Advances in solid-state white-light-emitting diodes (WLEDs) necessitate the urgent development of highly efficient single-phase phosphors with tunable photoluminescence properties. Herein, the Tm3+, Dy3+, and Sm3+ ions are incorporated into the orthorhombic NaGdTiO4 (NGT) phosphors, resulting in phosphors that fulfill the aforementioned requirement. The emission spectrum of Tm3+ ions overlaps well with the adsorption spectra of both Dy3+ and Sm3+ ions. Under the excitation at 358 nm, the single-phase NaGdTiO4: Tm3+, Dy3+, Sm3+ phosphor exhibits tunable emission peaks in the blue, yellow, and red regions simultaneously, resulting in an intense white-light emission. The coexisting energy transfer behaviors from Tm3+ to Dy3+ and Sm3+ ions and the energy transfer from Dy3+ to Sm3+ ions are demonstrated to be responsible for this phenomenon. The phosphors with multiple energy transfers enable the development of single-phase white-light-emitting phosphors for phosphor-converted WLEDs.
Highlights
White-light-emitting diodes (WLEDs) are considered as the generation of green lighting sources because of their low energy consumption, high output efficiency, and environmental friendliness, compared with traditional incandescent and fluorescent lamps [1,2,3,4]
There are two methods are available for generating white light: the multichip combination method, in which red, green, and blue LED chips are used in combination, and the light conversion method, in which various phosphors are excited by blue, ultraviolet (UV), or near-UV LED chips [5,6]
We prepared the NGT-based phosphors doped with various activator ions (Tm3+, Dy3+, and Sm3+) via a conventional solid-state reaction and studied their luminescence properties, energy transfer behavior, and tunable emission properties in detail
Summary
White-light-emitting diodes (WLEDs) are considered as the generation of green lighting sources because of their low energy consumption, high output efficiency, and environmental friendliness, compared with traditional incandescent and fluorescent lamps [1,2,3,4]. In the light conversion method, a yellow yttrium aluminum garnet phosphor powder such as (Y1-aGda)3(Al1-bGab)5O12:Ce3+ is excited by a blue LED chip [7,8,9]; the white-light is obtained when the blue and yellow light are combined, which is a more popular approach in high-efficiency commercial LEDs. the lack of a red-light component in the combined white-light results in a low color-rendering index, which is the main weakness of this approach for lighting [10,11]. The lack of a red-light component in the combined white-light results in a low color-rendering index, which is the main weakness of this approach for lighting [10,11] This disadvantage appears to be solvable by combining red, blue, and green tricolor phosphors excited by UV or near-UV LED chips. We prepared the NGT-based phosphors doped with various activator ions (Tm3+, Dy3+, and Sm3+) via a conventional solid-state reaction and studied their luminescence properties, energy transfer behavior, and tunable emission properties in detail
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