Strontium sulfide doped with copper has been regarded as one of the most promising inorganic materials for the blue-green color phosphor. A wet chemical precipitation method with post-annealing is presented for the synthesis of copper-doped SrS nanoparticles. XRD studies revealed the phase purity of SrS particles with rocksalt structure. TEM images showed the formation of nanoparticles with an average size of 7 nm. Green photoluminescence emission (PL) at 535 nm was observed for an excitation wavelength of 356 nm, the intensity of which was greater than that of coarser phosphor particles synthesized by solid state reaction. Low temperature PL showed a redshift with decreasing temperature which is due to aggregated copper centers. Luminescent decay at room temperature was found to be faster than the reported values of the corresponding transition in thin film samples. A blueshift in the absorption edge was observed for the nanophosphor with respect to the bulk due to reduction in particle size.
The fabrication of ZnS:Re, C1 thin-film electroluminescent (TFEL) devices and their emission characteristics are described. The various emission bands and lines observed in the spectra are assigned to the transitions within the RE 3~ ions. The operating voltages have been brought down below 50 V using devices with metal-insulator-semiconductor structure, with Sm203 as the insulator. Studies on the effect of halides (F-, CI-, Br-) and oxide (O~) on the EL emission spectra of ZnS:Pr TFEL devices show that the fluoride dopant produces the maximum brightness. The brightest of the ZnS:Re, CI devices studied, ZnS:Tb, C1, has a brightness of about 500 fL, about one-third that of a typical ZnS:Mn EL celt.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.126.162.126 Downloaded on 2015-03-14 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.126.162.126 Downloaded on 2015-03-14 to IP
AC thin film electroluminescent devices of MIS and MISIM have been fabricated with a novel dielectric layer of Eu2O3 as an insulator. The threshold voltage for light emission is found to depend strongly on the frequency of excitation source in these devices. These devices are fabricated with an active layer of ZnS:Mn and a novel dielectric layer of Eu2O3 as an insulator. The observed frequency dependence of brightness-voltage characteristics has been explained on the basis of the loss characteristic of the insulator layer. Changes in the threshold voltage and brightness with variation in emitting or insulating film thickness have been investigated in metal-insulator-semiconductor (MIS) structures. It has been found that the decrease in brightness occurring with decreasing ZnS layer thickness can be compensated by an increase in brightness obtained by reducing the insulator thickness. The optimal condition for low threshold voltage and higher stability has been shown to occur when the active layer to insulator thickness ratio lies between one and two.
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