Eu Phosphor Films Research Articles

Fabrication and characterization of a phosphor based photon conversion film

In this paper, morphological, structural, optical properties of phosphor and the phosphor based photon conversion films (pb-pc films) were studied. The overall performance of a pb-pc film was determined by the properties of the phosphor and matrix materials as well as their interaction. A quantitative relationship between the performance and the microstructure of the film which consists of CaS:Eu as phosphor and silicone as matrix material were investigated. A mathematical model was also proposed to describe the relationship of the optical properties of the phosphor composite films and their compositions. The simulated spectrum based on the mathematical model is found in good agreement with the one measured experimentally. The transmittance of the phosphor films decreases gradually with the phosphor concentration increases in the film. The CaS:Eu phosphor film can increase the color rendering index (CRI) Ra of the blue LED chips packaged with YAG:Ce phosphor film, the biggest Ra value is 90.9 when 25 wt% CaS:Eu phosphor film is used, indicating that the Ra value has increased 14% than the one without CaS:Eu phosphor film.

Fabrication and characterisation of a phosphor-based photon conversion film

In this paper, morphological, structural, optical properties of phosphor and the phosphor-based photon conversion films were studied. The overall performance of a phosphor-based photon conversion film was determined by the properties of the phosphor and matrix materials as well as their interaction. A quantitative relationship between the performance and microstructure of the film, which consists of CaS:Eu as phosphor and silicone as matrix material, were investigated. A mathematical model was also proposed to describe the relationship of the optical properties of the phosphor composite films and their compositions. The simulated spectrum based on the mathematical model is found in good agreement with the one measured experimentally. The transmittance of the phosphor films decreases gradually with the phosphor concentration increases in the film. The CaS:Eu phosphor film can increase the color rendering index (CRI) Ra of the blue LED chips packaged with YAG:Ce phosphor film, the biggest Ra value is 90.9 w...

Effect of annealing atmosphere and electron beam pre-irradiation on the properties of SrGa2S4:Eu phosphor films

Europium activated strontium thiogallate (SrGa2S4:Eu) phosphors were prepared by the deposition of SrS:Ga2S3:Eu films of about 1μm thickness onto quartz glass substrates by two electron beam (EB) evaporation followed by irradiation with 900keV accelerated electrons and subsequent annealing in either sulfur vapor or H2S(10%):Ar(90%) mixture at 900°С. Annealing in vaporized sulfur provides a significantly higher crystallinity and PL intensity of the obtained phosphor films in comparison with annealing in H2S:Ar mixture. Preliminary irradiation is found to further increase the crystallinity and photoluminescence (PL) intensity of the subsequently annealed phosphors due to the formation of crystallization centers.

X-ray imaging plate using CsBr:Eu phosphors for computed radiography

It is shown that X-ray-irradiated Eu-doped CsBr (CsBr:Eu) exhibits intense photostimulated luminescence (PSL). The peak wavelengths of PSL emission and stimulation spectra of CsBr:Eu phosphor ceramic samples are 450 and 690 nm, respectively. The dependence of PSL properties on preparing conditions of phosphor ceramic samples, such as Eu concentration, sintering temperature and sintering time, is studied. It is found that the PSL intensity of CsBr:Eu phosphor ceramics fabricated under optimum preparation condition is higher than that of commercially available imaging plates (IP) using BaFBr:Eu and BaFI:Eu. The image quality of the IP using CsBr:Eu phosphor film is better than that of commercially available IP.

Effects of Zn-doping on red-luminescence in Eu-doped (Mg,Ca)S phosphor films

For the improvement of emission efficiency, ZnS-doped Mg 0.8Ca 0.2S:Eu phosphor film was made using rf-magnetron sputtering method. When the concentration of ZnS in the film is 4%, the photoluminescence intensity is about three times higher than that of ZnS-non-doped Mg 0.8Ca 0.2S:Eu film with keeping pure red emission (∼650 nm). The crystal planes are oriented in (2 0 0) direction and make a solid solution with ZnS. Enhancement in photoluminescence (PL) intensity is closely related to the change of the crystal quality.

Critical issues in enhancing brightness in thin film phosphors for flat-panel display applications

Thin film phosphors have potential applications in field emission flat-panel displays. However, they are limited by the lower cathodoluminescent brightness in comparison to phosphor powders. In this paper, we have investigated the critical parameters that need to be optimized to increase the brightness of phosphor thin films. Specifically, we studied the role of surface roughness and optical properties of the substrate on the brightness of the phosphor films. Thin Y 2O 3:Eu phosphor films were deposited on various substrates (lanthanum aluminate, quartz, sapphire, and silicon) with thicknesses varying from 50 to 500 nm. A model that accounts for diffuse and specular or scattering effects has been developed to understand the effects of the microstructure on the emission characteristics of the cathodoluminescent films. The results from the model show that both the optical properties of the substrate and the surface roughness of the films play a critical role in controlling the brightness of laser deposited phosphor films.

Growth of Y2O2S:Eu Thin Films by Reactive Magnetron Sputtering and Electroluminescent Characteristics

Y2O2S:Eu phosphor films were prepared by reactive magnetron sputtering with a Y2O3:Eu target in a H2S and argon mixed atmosphere, and hot carrier injection (HCI)-type EL devices with Y2O2S:Eu/ZnS/Y2O2S:Eu structure were fabricated. It is found that the crystal structure of Y2O2S:Eu films depends on the sulfur concentration in the film. With increasing atomic ratios of S/Y, the crystal phase is changed from cubic to hexagonal. Luminescent spectra from the films are dependent on the crystal structures.