Nanotech 2010

Enhanced Photoluminescence Properties of Li/Al-doped YPO4:Eu phosphors

R. Balakrishnaiah, D.W. Kim, S.S. Yi, S.H. Kim, K. Jang, H.S. Lee, B.K. Moon, J.H. Jeong
Silla University, KR

Keywords: photoluminescence, Eu-doped phosphor, solid state reaction method

Abstract:

Different concentrations of Li/Al-doped YPO4:Eu0.05 phosphors have been synthesized by solid state reaction method and are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), excitation and emission measurements. The dependence of various optical and morphological properties of the prepared materials on Li/Al concentration has been discussed in the present work. Incorporation of Li+ and Al3+ ions into the YPO4:Eu phosphors has greatly enhanced the crystallinity, particle size and hence the luminescence properties and the optimum concentration in case of both Li and Al dopants are found to be 10 mol %. An intense reddish orange emission which is visible to the naked eye, is observed under 232 as well as 394 nm NUV excitation wavelengths and the intensity is found stable even after one year from the date of preparation of the samples. The red to orange emission intensity ratio also significantly varied with dopant concentration. The improvement in PL performance with Li/Al-doping may result not only from the improved crystallinity but also from the enlarged grain sizes inducing lower scattering loss and distortion of symmetry. The results are discussed in comparison of results with similar reported works. The observed intense and stable reddish orange emission under NUV excitation provides a hope for suitability of this phosphor for applications in UV-based LEDs.
 
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