Paul J. Marsh

Engineering phosphors for field emission displays

Factors affecting the synthesis and properties of a new generation of fine particle low voltage phosphors in field emission displays are reviewed. The morphology and particle size, the composition and stoichiometry, the stability, together with the nature and shape of the particle surface, all play important roles in the performance of the final phosphor. Initial new results from novel synthetic methodology are presented and discussed. Their implications in the light of the known literature point the way to the successful conclusion of the current thrust of phosphor research for good red, green, and blue low voltage, high definition phosphors.

Cathodoluminescence studies of yttrium silicate:cerium phosphors synthesised by a sol–gel process

Sol–gel chemistry has been used to produce a Y2SiO5:Ce phosphor with good chromaticity and brightness. Although, the chromaticity of Y2SiO5:Ce1% was similar to that of a commercial Y2SiO5:Ce phosphor, it was B20–25% brighter. Yttrium silicate:cerium phosphors that contained a range of gadolinium concentrations were also prepared by the sol– gel route, and their luminescence properties under cathodoluminescent conditions were measured. Over the range of gadolinium concentrations, there was no significant change in the chromaticity of the phosphors, but the addition of gadolinium resulted in a B20% loss in brightness compared to Y2SiO5:Ce1% synthesised by the sol–gel route. r 2002 Elsevier Science B.V. All rights reserved.

A Novel Method for the Synthesis of ZnS for Use in the Preparation of Phosphors for CRT Devices

The decomposition of thiourea dioxide in aqueous solution at elevated temperatures, in the presence of zinc acetate, has been used to precipitate ZnS. The important reaction pathway for the formation of sulfide ions has been elucidated, and some common ZnS S phosphors have been prepared from the precipitate. The preparation of ZnS by this method is extremely simple and does not yield large amounts of liquid or gas containing volatile sulfur species Thus, this method has been shown to be an excellent method for the preparation of ZnS phosphors, particularly copper-activated materials, requiring no purification of the reagents, with little production of sulfur-containing waste species, and resulting in small particle size powders without postproduction milling or separation of the powders. These phosphors have been shown to have exceptional luminescent properties compared to standard commercial materials.

A Novel Method for the Preparation of Inorganic Sulfides and Selenides. I. Binary Materials and Group II–VI Phosphors

A novel method for the synthesis of wide range of metal sulfides and selenides is described. Polysulfide solutions formed by the dissolution of sulfur in hydrazine monohydrate have been shown to contain the hexasulfide and tetrasulfide anions. The action of these solutions, or their selenium analogues, with a range of transition and main group metal salt solutions yields a precipitate, which after firing at an elevated temperature, forms a crystalline metal sulfide or selenide. This method of preparing metal chalcogenides has been extended to some group II-VI phosphors with promising luminescent properties.

A Method for the Clean Syntheses of Sulfides/Selenides II. Ternary Sulfides/Selenides

The syntheses of MGa 2 S 4 (where M = Ca, Sr, and Zn), CuMS 2 (where M = In or Cr). Ba 2 ZnS 3 , and CuInSe 2 by utilizing sulfur or selenium solutions in hydrazine monohydrate are reported. Scanning electron microscope studies of the morphology of the resulting materials prepared by this route are presented. The photoluminescence spectra of the phosphors SrGa 2 S 4 :Eu. SrGa 2 S 4 :Ce, ZnGa 2 S 4 :Mn, CaGa 2 S 4 :Eu, and Ba 2 ZnS 3 :Mn are displayed. The method is more environmentally friendly than traditional preparations (very little sulfur-based gases are formed). Additionally, it is a simple and rapid preparation, producing a good yield. The procedure facilitates the formation of ternary metal sulfides or selenides. It is further shown that for optimum performance of SrGa 2 S 4 :Eu, the phosphor needs to be fired in a reducing atmosphere to convert all of the Eu 3+ to Eu 2+ .

AC powder electroluminescent displays

Abstract— The current status of AC powder electroluminescent (ACPEL) displays is reviewed with particular emphasis given to color and lifetime. The printing of the displays in forward and reverse architectures is also discussed, in addition to the fabrication of ACPEL displays with interdigitated electrodes, and different types of ACPEL phosphors and materials for back electrodes, transparent conducting electrodes, binders, and dielectrics are considered. Furthermore, shape conformable and highly flexible ACPEL displays are surveyed.

Structure and Morphology of ACEL ZnS:Cu,Cl Phosphor Powder Etched by Hydrochloric Acid

© The Electrochemical Society, Inc. 2009. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version is available at the link below.

39.1: Invited Paper: Submicron Spherical Phosphors for FED Applications

New synthetic routes using controlled precipitation and firing have led to the preparation of submicron phosphors. In this way, fine particle (0.25–0.5μm) phosphors have been prepared. These compare favourably to present industrial phosphors (3–8μm) with respect to efficiency and brightness at low voltage (300–5000V). The work is now being extended to oxides and binary and ternary sulphides, with considerable promise, although further optimisation is still required.

49.1: Improved Zinc-Sulfide-Type Phosphors by a Novel Synthetic Method

A novel, quick, and “clean”, method has been developed for the preparation of zinc sulfide phosphors for CRT and FED applications. The method involves the addition of a solution of sulfur in hydrazine monohydrate to a zinc salt solution, which results in precipitation of zinc sulfide, Firing this material has resulted in bright, efficient phosphors with improved luminescent properties between 500–15,000 eV, particularly for copper and silver activated ZnS.

Optical studies on composite Langmuir-Blodgett films containing ytterbium bis-phthalocyanine

Abstract Langmuir films of pure ytterbium bis-phthalocyanine (YbPc2) molecules and its mixtures with calix[4]resorcinarene (C[4]RA) molecules were studied by UV–vis absorption spectra and surface pressure–area (II–A) isotherm measurements. Langmuir–Blodgett (LB) films of both pure YbPc2 and YbPc2–C[4]RA mixtures were produced and characterized with UV–vis spectra and surface plasms on resonance (SPR). In the case of LB films of pure YbPc2 molecules, values of 1.68 × 107 m−1 and 1.76% were found for the absorption coefficient at spectral maxima and the reflectance loss. Mixed YbPc2–C[4]RA films give smaller values depending on the mixing ratio. SPR measurements, made in two media with different refractive indices, yielded accurate values of thickness of 2.06 ± 0.06 nm and refractive index of 1.70 ± 0.02 for LB films of pure YbPc2 molecules. Electrochromic effects, driven by electrochemical oxidation/reduction of the Yb central atom, were registered in LB films of pure YbPc2 molecules by both UV–vis absorpt...