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Detailed Program
Paper Number : GL-O10
Time Frame : 14:43~14:55
Presentation Date : Thurse day, 27, November
Session Name : Glass & Optp-Electonic Materials
Session Chair 1# : Woon Jin Chung
Session Chair 2# : Hirokazu Masai
Improved Luminous Efficacy by Enhancing Transmittance of Phosphor-in-Glass
Yurian KIM
Inha University
The color converters for phosphor-in-glass (PIG) have been recently researched in order to improve luminous properties of LED packages by changing composition of glass frit, phosphor ratio and thickness of plates. The residual pores of sintered glass plate generally govern the transmittance. It is considered as a factor affecting the luminous properties. In this study, the sintered glass and PIG plates were fabricated in various sintering temperature and time, and the correlation between the pores of the sintered glass and the optical properties of the glass and PIG plates were investigated. The pore features were analyzed using scanning electron microscope, and the transmittance was measured by UV-visible spectrum. The luminous properties of PIG were evaluated using an integrating sphere. The transmittance of sintered glass and PIG plates was calculated as a function of porosity and pore average size with the Mie light scattering theory. The highest value in transmittance of glass plates was 48% at 550 nm and luminous efficacy of PIG is 71.7lm/W. The effective scattering coefficient increased with the increase of porosity in both sintered glass and PIG plates. The luminous properties such as luminous efficacy and emission intensity linearly increased with increasing transmittance of PIG plates. The increase in luminous efficacy of PIG was attributed to decrease in light scattering loss. These results indicate that the high transmittance of PIG can increase the interaction between phosphor and light rays coming from blue LED chip and will cause emission of white light from PIG plate. The CRI remained constant with increase transmittance. On the other hand, the CCT showed the similar trend to luminous efficacy, and the color coordinates of emission light were shifted from blue to yellow region owing to low PIG transmittance.

References:

[1] Y. Lee, J. Lee, J. Heo, W. Im, and W. Chung, Opt. Lett. 37 (2012) 15.
[2] R. Boulesteix, A. Maitre, J. Baumard, Y. Rabinovitch, and F. Reynaud, Opt. Express 18 (2010) 14.
[3] I. Yamashita, H. Nagayama, and K. Tsukuma, J. Am. Ceram. Soc. 91 (2008) 8.
Acknowledgements : This work was supported by the Technology Innovation Program (10044203, Development of phosphor materials based on Blue/UV LED) funded by the Ministry of Trade, industry & Energy (MI, Korea).