Since Eu-complex generates bright red-emission by a violet excitation, it has been attracted much attention as phosphors for white light-emitting diodes (LEDs). However, the organic-ligand of Eu-complex is easily decomposed by free oxygen and water. In previous papers, we demonstrated the encapsulation technique of Eu-complex using the sol-gel derived silica glass. In this research, we used tetraethoxysilane, deionized water, ethanol, N,N-Dimethoxyformamide, and ammonia for a starting solution to form the silica glass around Eu-complex. By optimizing the fabrication condition, the nano-sized Eu(TTA)_3phen encapsulated by the sol-gel derived silica glass was successfully achieved. The Eu(TTA)_3phen powder showed a half brightness time of 67 minute while irradiating the ultraviolet light with the center wavelength of 360nm and the optical intensity of 5mW/cm^2, however, that of the encapsulated sample indicated that of 262 minutes. The improvement in the half brightness time was realized approximately 4-times by optimizing the encapsulating process.
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