Warm white light emitting from single composition SrGa₁₂O₁₉:Dy³⁺ phosphors for AC‐LED

Abstract

Making illumination light sources become comfortable to the human eye is a long‐term effort, which justifies the current research on warm white‐light‐emitting diodes (w‐LEDs). In this work, a novel phosphor for w‐LEDs, namely SrGa12O19: Dy3+(SGO: Dy3+), with a low‐color temperature (CT) was designed and synthesized. The crystal structure, the luminescence properties, the thermoluminescence properties and the stability of SGO: Dy3+ were investigated. We demonstrate outstanding luminescent characteristics and excellent stabilities. The intensity of emission light keep remained when excited by a flickering light source with a chopping speed or off‐time of a few seconds, which indicates that the SGO: Dy3+ phosphor has anti‐flicker properties that will be useful for potential applications, as LEDs driven by alternating current (AC‐LED). The chromaticity coordinates and the correlated color temperature (CCT) of SGO: Dy3+ phosphors with different Dy3+ concentrations are close with an optimal doping at 4.00 mol% Dy3+ for chromaticity coordinate (0.4269, 0.4348) and a lowest CCT of 3361 K. The perfect weatherability of this phosphor was also confirmed since the phosphorescence intensity and the color were stable at high temperature and in a high humidity environment. The performance obtained shows that SGO: Dy3+ is a suitable candidate for illumination sources that are beneficial to human health.

Dy3+‐doped Y2Zr2O7 highly transparent ceramics for ultraviolet excitable warm white light‐emitting applications

“…In general, the light located in the blue waveband could suppress inflammation in human wounds, 1 whereas the green region can improve skin roughness caused by overwork and stress, 2 and the red part tends to reduce blood lipids and blood viscosity and could prolong the flowering period of plants 3 . Especially, the light radiation assigned in the warm white region is highly desirable for humans because this illumination light source with a low correlated color temperature (CCT) light (CCT ≤ 4500 K or even CCT ≤ 3500 K) can help autonomic relax, provide a warm and comfortable atmosphere, and can even avoid some diseases 4–7 . Moreover, with the remarkable development of UV‐LED diodes, the realization of white light‐emitting phosphors under ultraviolet excitation has been well demonstrated and developed 8 .…”

“…Benefited from the emission originating from the 4 F 9/2 → 6 H 13/2 transition of Dy 3+ centered at about 580 nm; thus, Dy 3+ ‐doped phosphor materials have emerged as an especially robust representative to obtain the effective warm white luminescence 4 . However, the conventional Dy‐based composite luminescence converters fabricated by embedding phosphor powders in organic binders with poor chemical, thermal, and optical stability, which limited their further development in high‐power, high‐brightness solid‐state lighting 4,8,10 . As an alternative, some Dy‐doped glass converters have been developed, but the poor physical and chemical stabilities of the glass–ceramics make them unsuitable to be served in some harsh cases 11,12 .…”

“…3 Especially, the light radiation assigned in the warm white region is highly desirable for humans because this illumination light source with a low correlated color temperature (CCT) light (CCT ≤ 4500 K or even CCT ≤ 3500 K) can help autonomic relax, provide a warm and comfortable atmosphere, and can even avoid some diseases. [4][5][6][7] Moreover, with the remarkable development of UV-LED diodes, the realization of white light-emitting phosphors under ultraviolet excitation has been well demonstrated and developed. 8 Moreover, Nakajima et al found that the development of a warm white LED consisting of the greenish-yellow phosphor excited by UV-LED could be reducing photosynthesis.…”

“…4 However, the conventional Dy-based composite luminescence converters fabricated by embedding phosphor powders in organic binders with poor chemical, thermal, and optical stability, which limited their further development in high-power, high-brightness solid-state lighting. 4,8,10 As an alternative, some Dy-doped glass converters have been developed, but the poor physical and chemical stabilities of the glass-ceramics make them unsuitable to be served in some harsh cases. 11,12 To address these shortcomings, researchers have been working on developing innovative light-emitting converter materials with the potential for extreme environmental use, among which the polycrystalline ceramic phosphors are becoming a promising candidate due to their good optical transparency, high strength, corrosion and high-temperature resistance, and so on.…”

Novel organic–inorganic hybrid powder SrGa12O19:Mn2+–ethyl cellulose for efficient latent fingerprint recognitionviatime-gated fluorescence

“…SGO is a superior aerglow host lattice, as reported in our previous works, and the proper crystal eld environment for Mn 2+ ions' narrow band emitting can be provided by the SGO host. 35 EC is a common cellulose with chemical stability, thermal stability, superior cohesiveness, and desirable hydrophobicity. A series of SGO:Mn phosphors functionalized with methyl and ethyl groups in EC generated hydrophobic interactions with the LFPs.…”