Facile synthesis of the desired red phosphor Li₂Ca₂Mg₂Si₂N₆:Eu²⁺ for high CRI white LEDs and plant growth LED device

Abstract

The red emission with suitable peak wavelength and narrow band is acutely required for high color rendering index (CRI) white LEDs without at the cost of the luminous efficacy. Herein, the Li2Ca2Mg2Si2N6:Eu2+ red phosphor was prepared with facile solid‐state method using Ca3N2, Mg3N2, Si3N4, Li3N, and Eu2O3 as the safety raw materials under atmospheric pressure for the first time, which shows red emission peaking at 638 nm with full width at half maximum (FWHM) of 62 nm under blue light irradiation and becomes the desired red phosphor to realize the balance between luminous efficacy and high CRI in white LEDs. The morphology, structure, luminescence properties, thermal quenching behavior, and chromaticity stability of the Li2Ca2Mg2Si2N6:Eu2+ phosphor are investigated in detail. Concentration quenching occurs when the Eu2+ content exceeds 1.0 mol%, whereas high‐temperature photoluminescent measurements show a 32% drop from the room‐temperature efficiency at 423 K. In view of the excellent luminescence performances of Li2Ca2Mg2Si2N6:Eu2+ phosphor, a white LEDs with CRI of 91 as a proof‐of‐concept experiment was fabricated by coating the title phosphor with Y3Al5O12:Ce3+ on a blue LED chip. In addition, the potential application of the title phosphor in plant growth LED device was also demonstrated. All the results indicate that Li2Ca2Mg2Si2N6:Eu2+ is a promising red‐emitting phosphor for blue LED‐based high CRI white LEDs and plant growth lighting sources.

Sr/Ba substitution induced higher thermal stability far red-emitting Ba1−ySryLaLiWO6:Mn4+ phosphors for plant growth applications

“…Considering the D r value and valence state, the result indicates that the Mn 4+ ions incline more to substitute the W 6+ ions in the matrix. 12–14…”

“…At present, Pc-LEDs with visible light have been widely studied, while phosphors emitting deep red light have been less reported. Although Eu 2+ phosphors exhibit broadband emission and overlap well with the red light absorption of plants, such as Ba 3 CaK(PO 4 ) 3 :Eu 2+ , 11 Li 2 Ca 2 Mg 2 Si 2 N 6 :Eu 2+ , 12 Rb 3 YSi 2 O 7 :Eu 2+ , 13 and Sr/Ba[Mg 2 Al 2 N 4 ]:Eu 2+ , 14 the reduction environment required for the preparation of Eu 2+ phosphors and the coexistence of Eu 2+ and Eu 3+ limit their application. For transition metal ions such as Cr 3+ , the emission band often shows broadband emission, which cannot match well with the absorption band of plants.…”

Cool green-emissive Y2Si2O7:Tb3+ nanophosphor: auto-combustion synthesis and structural and photoluminescence characteristics with good thermal stability for lighting applications

“…14,15 However, these WLEDs oen lack a red module in the visible range, resulting in a white emission with a subpar color-renderingindex and high correlated-color-temperature. 16 To address this issue, an alternative approach involves coating primary red, green, and blue nanophosphors onto a NUV-LED chip, aiming to achieve WLEDs with high rendering-index, proper CCT and adjustable color characteristics. [17][18][19] Few studies have been conducted on yttrium orthosilicates (YSO) and for a long time, the focus of research on the luminous characteristics of RE-activated yttrium silicates was only on yttrium pyrosilicates (YPS).…”

A far-red-emitting ZnAl1.95Cr0.05O4 phosphor for plant growth LED applications

“…Light-conversion technology has continually been cited as one of the crucial methods to develop and improve the efficiency of plant cultivation. 10–12 It is well known that light has a variety of roles in plant growth at different wavelengths. Blue (410–500 nm), red (620–690 nm), and far-red (700–740 nm) photons required for photosynthesis, phototropism, and photomorphogenesis in plants, respectively, are absorbed by chlorophyll b , phytochrome PR, and PFR.…”