Luminescence Optimization of M[sub 3]MgSi[sub 2]O[sub 8]:Eu[sup 2+] Phosphor by Spray Pyrolysis Combined with Combinatorial Chemistry for UV-LED Application

Abstract

Spray pyrolysis was applied to prepare Eu 2+ -doped M 3 MgSi 2 O 8 ͑M = Ca, Sr, Ba͒ phosphor for near-ultraviolet ͑NUV͒ lightemitting diode ͑LED͒ application. The luminescence characteristics were optimized by a combinatorial screening method combined with spray pyrolysis for the Ca-Sr-Ba ternary system. The first composition library was obtained by measuring the emission spectrum under 395 NUV excitation. In this first screening, the highest luminescence intensity was obtained at ͑Ca 0.9 Sr 1.2 Ba 0.9 ͒MgSi 2 O 8 :Eu 2+ , which had 48% enhancement in the integrated emission intensity compared with Sr 3 MgSi 2 O 8 :Eu 2+ phosphor. The second screening was conducted for the potential compositions in the first library. As a result, the optimized composition was ͑Ca 0.9 Sr 0.45 Ba 1.65 ͒MgSi 2 O 8 :Eu 2+ , which showed 170% enhancement in the integrated emission intensity compared with Sr 3 MgSi 2 O 8 :Eu 2+ phosphor.In recent years much attention has been given toward developing renewable energy resources or new energy-efficient products. The indoor and outdoor lighting is necessary not only to get rid of darkness but also to exchange information through computers and displays. The lighting sources are a big part of the total energy consumption in human life. Therefore, great efforts have been focused on developing a new lighting source with high energy efficiency. White light-emitting diodes ͑LEDs͒ are considered a nextgeneration light source because they have much higher efficiency than conventional fluorescent lamps and no pollutant such as mercury. 1 Currently commercialized white LEDs are fabricated by combining InGaN blue LED and ͑Y,Gd͒ 3 ͑Al,Ga͒ 5 O 12 :Ce 3+ ͑YAG:Ce 3+ ͒ yellow phosphor. 2 The white LEDs ͑blue LED + yellow phosphor͒, however, have a bad color rendering index because the YAG:Ce phosphor has relatively weak emission in the red color region. 3,4 One way to improve such a low color rendering index is to use green and red phosphor with the blue LED. 5,6 Another convenient approach to make warm white LEDs with good color rendering index and high efficiency is to combine the nearultraviolet ͑NUV͒ LED with red, green, and blue phosphors. 7-11 Phosphors directly influence the efficiency of the white LED products. The development of red-green-blue phosphor with high conversion efficiency is essential to meet the requirements of consumers. Therefore, much research has been focused on the development of new phosphor materials or optimization of luminescence efficiency. [12][13][14][15] Eu 2+ -doped M 3 MgSi 2 O 8 ͑M = Ca, Sr, Ba͒ phosphor has high efficiency under NUV excitation and it has a blue band emission due to 4f 7 -4f 6 5d transition of Eu 2+ ions. 9,16-18 The emission peak position of M 3 MgSi 2 O 8 :Eu 2+ phosphor becomes short and narrow progressively as the radius of M ions increases. 19 Recently, Kim et al. studied the possibility of M 3 MgSi 2 O 8 :Eu 2+ ,Mn 2+ as the white phosphor. 20 Pan and Ning studied the luminescence properties of Sr 3 MgSi 2 O 8 :Eu 2+ ,Dy 3+ phosphor. 21 Accordin...

Luminescence of Eu2+ Ions in CsMgPO4 Phosphor: Anomalous Emission and its Origin

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Sol–gel synthesis and luminescence characteristics of Sr(3−(2x+y))MgSi2O8: (Ce3+,Li+)x, Euy2+ phosphor for solid state lighting

“…One such metal silicate is the Sr 3 MgSi 2 O 8 which is the highlight of the present work. Several methods are used to synthesis the Sr 3 MgSi 2 O 8 based silicate phosphors, namely solid state technique [6], combustion synthesis [7], spray -pyrolysis [8], nano coating methods [9] to tune the chemical, physical and luminescent properties have also been reported. The phosphor prepared by sol-gel method possesses many advantages, such as uniform composition, fine grain size, low impurity and low synthesis temperature.…”

Luminescence optimization of Eu-doped LnAl3(BO3)4 (Ln=Y, Gd) red phosphor using spray pyrolysis

“…Also, a solidstate reaction method was mostly used to prepare the LnAl 3 (BO 3 ) 4 :Eu 3 + phosphor [11][12][13][15][16][17]. Spray pyrolysis is one of the promising methods to prepare phosphors, which consist of multi-components [18][19][20][21][22]. Compared with the conventional solid-state reaction route, spray pyrolysis does not need a milling step and makes it possible to prepare phosphor particles with fine size, narrow size distribution, good crystallinity, and high phase purity.…”