The baricenter and crystal field splitting of the 5d transition of the Eu 2+ activator were approximated from the experimental spectrum data for Li 2 SrSiO 4 , Li 2 CaSiO 4 , and Li 2 BaSiO 4 hosts and examined in conjunction with the ionic radii of neighboring alkali earth ions and the local structure around the divalent europium activator. In addition, Li 2 ͑Sr,Ca,Ba͒SiO 4 :Eu 2+ ternary phosphors were screened in terms of photoluminescence ͑PL͒ intensity and color chromaticity at an excitation of 400 nm to determine their suitability for use in white-light-emitting diodes. As a result, several intermediate compounds ͑mixtures or solid solutions͒ were pinpointed in a specific composition range in the Li 2 ͑Sr,Ca,Ba͒SiO 4 :Eu 2+ ternary composition library. In particular, Li 2 ͑Ba 1−x Sr x ͒SiO 4 :Eu 2+ ͑0.3 Ͻ x Ͻ 0.6͒ showed the best performance in terms of both PL intensity and color chromaticity.Light-emitting diodes ͑LEDs͒ for solid-state lighting have significant potential in terms of energy savings and environmental advantages, and are expected to replace most gas discharge fluorescent lamps in the near future. 1,2 There are several ways of constituting white light based on the LED technique, each of which involves various phosphors which emit visible light by absorbing soft UV or blue light produced by LEDs. When LED phosphors are categorized with respect to their composition we can enumerate various oxides, sulfides ͑or chalcogenides͒, and nitrides ͑or oxynitrides͒. The representative oxide phosphors are Y 3 Al 5 O 12 :Ce 3+ and its variants, 3 and divalent europium-doped ortho-silicate phosphors. 4 These oxide phosphors emit yellow light and work best when combined with 460 nm blue-emitting LED chips, but all of them have a low color rendering index ͑CRI͒. A great deal of attention has been focused on sulfide ͑or chalcogenide͒ phosphors such as SrGa͑S,Se͒:Eu 2+ ͑green͒ and ͑Sr,Ca͒͑S,Se͒:Eu 2+ ͑red͒ due to their yellow-green and red color emission under soft UV excitations. However, the sulfide phosphors have a serious drawback with respect to long-term stability, though they exhibit high luminescent efficiency and improved CRI. In addition, nitride ͑or oxynitride͒ phosphors have been developed most recently and are still in the early stages of development. Nitride red phosphors such as divalent europium-doped CaAlSiN 3 and ͑Ca,Sr͒ 2 Si 5 N 8 are already commercially available, and Ca ͑or Li͒, ␣-sialon, 5,6 and strontium/barium nitridosilicates 7-9 are under consideration for use in white-LEDS ͑WLEDs͒. However, in-depth studies on the 5d energy in the above-described oxide and nitride phosphors are lacking, despite the successful commercialization of these phosphors.The aim of the present investigation is to examine some silicate phosphors such as Li 2 SrSiO 4 :Eu 2+ ͑LSSO͒, Li 2 CaSiO 4 :Eu 2+ ͑LCSO͒, and Li 2 BaSiO 4 :Eu 2+ ͑LBSO͒ phosphors based on their potential for use in WLEDs for LSSO, LCSO, and LBSO phosphors in association with their exact structure. In fact, LSSO, LCSO, and LBSO phosphors have...

A multi‐objective genetic algorithm‐assisted combinatorial materials search (MOGACMS) strategy was employed to develop a new green phosphor for use in a cold cathode fluorescent lamp (CCFL) for a back light unit (BLU) in liquid crystal display (LCD) applications. MOGACMS is a method for the systematic control of experimental inconsistency, which is one of the most troublesome and difficult problems in high‐throughput combinatorial experiments. Experimental inconsistency is a very serious problem faced by all scientists in the field of combinatorial materials science. For this study, experimental inconsistency and material property were selected as dual objective functions that were simultaneously optimized. Specifically, in an attempt to search for promising phosphors with high reproducibility, luminance was maximized and experimental inconsistency was minimized using the MOGACMS strategy. A divalent manganese‐doped alkali alkaline germanium oxide system was screened using MOGACMS. As a result of MOGA reiteration, we identified a phosphor, Na2MgGeO4:Mn2+, with improved luminance and reliable reproducibility.

A genetic algorithm was employed in association with high-throughput synthesis and characterization in an attempt to search for red phosphors with high photoluminescent intensity. A tetravalent manganese-doped alkali earth germanium oxide system, with an emission color close to a desirable deep red, was screened with the assistance of a genetic algorithm to pinpoint the phosphor exhibiting the highest photoluminescence. As the genetic algorithm was in progress, the PL intensity increased and maximized in the fourth generation. The highest and the average PL intensity of the fourth generation improved by 23 and 120%, respectively, compared with that of the first generation.

Acquiring materials that simultaneously meet two or more conflicting requirements is very difficult. For instance, a situation wherein the color chromaticity and photoluminescence (PL) intensity of phosphors conflict with one another is a frequent problem. Therefore, identification of a good phosphor that simultaneously exhibits both desirable PL intensity and color chromaticity is a challenge. A high‐throughput synthesis and characterization strategy that was reinforced by a nondominated sorting genetic algorithm (NSGA)‐based optimization process was employed to simultaneously optimize both the PL intensity and color chromaticity of a MgO–ZnO–SrO–CaO–BaO–Al2O3–Ga2O3–MnO system. NSGA operations, such as Pareto sorting and niche sharing, and the ensuing high‐throughput synthesis and characterization resulted in identification of promising green phosphors, i.e., Mn2+‐doped AB2O4 (A = alkali earth, B = Al and Ga) spinel solid solutions, for use in either plasma display panels or cold cathode fluorescent lamps.

We developed a method to systematically control experimental inconsistency, which is one of the most troublesome and difficult problems in high-throughput combinatorial experiments. The topic of experimental inconsistency is never addressed, even though all scientists in the field of combinatorial materials science face this very serious problem. Experimental inconsistency and material property were selected as dual objective functions that were simultaneously optimized. Specifically, in an attempt to search for promising phosphors with high reproducibility, photoluminescence (PL) intensity was maximized, and experimental inconsistency was minimized by employing a multiobjective evolutionary optimization-assisted combinatorial materials search (MOEO combinatorial material search) strategy. A tetravalent manganese-doped alkali earth germanium/titanium oxide system was used as a model system to be screened using MOEO combinatorial materials search. As a result of MOEO reiteration, we identified a halide-detached deep red phosphor with improved PL intensity and reliable reproducibility.