플라즈마 소수성 코팅을 이용한 실리케이트계 황색형광체의 내구성 개선에 관한 연구

장두일; 조진오; 고란영; 이상백; 목영선; Doo Il Jang; Jin Oh Jo; Ranyoung Ko; Sang Baek Lee; Young Sun Mok

Korean Chemical Engineering Research, Vol.51, No.2, 214-220, April, 2013

Export Citation

플라즈마 소수성 코팅을 이용한 실리케이트계 황색형광체의 내구성 개선에 관한 연구

Plasma-mediated Hydrophobic Coating on a Silicate-based Yellow Phosphor for the Enhancement of Durability

장두일, 조진오, 고란영, 이상백, 목영선 ^†

제주대학교 생명화학공학과, 690-756 제주도 제주시 제주대학로 102

Doo Il Jang, Jin Oh Jo, Ranyoung Ko, Sang Baek Lee, and Young Sun Mok^†

Department of Chemical and Biological Engineering, Jeju National University, 102 Jejudaehakno, Jeju-si, Jeju Special Self-Governing Province 690-756, Korea

E-mail:

초록

본 연구에서는 실리케이트계 황색 형광체(Sr2SiO4:Eu2+)의 신뢰성 향상을 위하여 대기압 유전체장벽방전 플라즈마를 이용하여 hexamethyldisiloxane (HMDSO, C6H18OSi2)을 형광체 분말에 코팅하였다. 플라즈마 코팅 후의 형광체 분말 특성은 주사전자현미경(scanning electron microscope), 투과전자현미경(transmission electron microscope), 형광분광광도계(fluorescence spectrophotometer) 및 접촉각측정기(contact angle analyzer)를 이용하여 조사되었다. 형광체 분말의 플라즈마 코팅 후 접촉각이 133.0°(물)와 140.5°(글리세롤)로 증가하여 표면이 소수성으로 변화되었음을 확인하였으며, 광발광(photoluminescence)은 최대 7.8%의 향상을 나타냄을 알 수 있었다. 플라즈마 코팅 후 형광체 표면의 주사전자 현미경 및 투과전자현미경 사진을 통해 낟알형상의 표면조직이 박막 코팅 층으로 덮여 있고, 코팅 층은 31~46 nm 가량의 두께로 형성되어 있음을 확인하였다. 발광다이오드(3528 1 칩 LED)에 형광체를 실장한 후 85 ℃와 85% 상대습도에서 1,000시간 동안 신뢰성 테스트(85-85 Test)를 수행한 결과 코팅이 되지 않은 경우와 비교하여 코팅후의 형광체가 광도 저하율에서도 개선 효과를 보이는 것으로 나타났다. 본 연구의 유전체장벽방전 플라즈마 코팅 방법은 불규칙한 입자 형태의 형광체 분말 표면을 입체적으로 코팅하여 제품의 신뢰성을 향상시킬 수 있는 방법으로 판단된다.

Hydrophobic coating on a silicate-based yellow phosphor (Sr2SiO4:Eu2+) was carried out by using hexamethyldisiloxane (HMDSO) precursor in an atmospheric pressure dielectric barrier discharge plasma reactor, eventually to improve the long-term stability and reliability of the phosphor. The phosphor powder samples were characterized by a scanning electron microscope (SEM), a transmission electron microscope (TEM), a fluorescence spectrophotometer and a contact angle analyzer. After the coating was prepared, the contact angle of the phosphor powder increased to 133.0° for water and to 140.5° for glycerol, indicating that a hydrophobic layer was formed on its surface. The phosphor coated with HMDSO exhibited photoluminescence enhancement up to 7.8%. The SEM and TEM images of the phosphor powder revealed that the plasma coating led to a morphological change from grain-like structure to smooth surface with 31~46 nm thick hydrophobic layer. The light emitting diode (3528 1 chip LED) fabricated with the coated phosphor showed a substantial enhancement in the reliability under a special test condition at 85 ℃ and 85% relative humidity for 1,000 h (85/85 testing). The plasma-mediated method proposed in this work may be applicable to the formation of 3-dimensional coating layer on irregular-shaped phosphor powder, thereby improving the reliability.

Keywords:Hydrophobic Coating;Silicate Phosphor;Dielectric Barrier Discharge;Hexamethyldisiloxane

[References]

Lee KH, Cho SC, Jo SY, Uhm HS, J. Korean Phys.Soc., 53(2), 631 (2008)
Jo SY, Cho SC, Lee KH, Uhm HS, J. Korean Phys. Soc., 53(2), 641 (2008)
Topala I, Asandulesa M, Spridon D, Dumitrascu N, IEEE Trans. Plasma Sci., 37(6), 946 (2009)
Kim JH, Yang WY, Hahn YB, Korean Chem. Eng. Res., 49(3), 357 (2011)
Kakiuchi H, Ohmi H, Yamada T, Yokoyama K, Okamura K, Yasutake K, Plasma Chem. Plasma Process., 32(3), 533 (2012)
Fang J, Huang Y, Li X, Dou X, J. Raman Spectrosc., 35, 914 (2004)
Vogelsang A, Ohl A, Foest R, Schrder K, Weltmann KD, J. Phys. D: Appl. Phys., 43, 485201 (2010)
Mok YS, Jo JO, Whitehead JC, Chem. Eng. J., 142(1), 56 (2008)
Qiao Y, Zhang X, Ye X, Chen Y, Guo H, J. Rare Earths., 27(2), 323 (2009)
Garbassi F, Morra M, Occhiello E, Polymer Surface from Physics to Technology, John Willey & Sons, 301 (1994)
Kim JM, Park JK, Kim KN, Lee SJ, Kim CH, Jang HG, J. Korea Chem. Soc., 50(3), 237 (2006)
Seo JH, “The Surface Modification of Phosphors by Coating with Nano-oxide,” Thesis, Kyungpook Nat’l. Univ., Daegu, Korea (2009)
Ko RY, “Synthesis of Sr2SiO4:Eu2+ Phosphors with Nonthermal Plasma Discharge,” Thesis, Jeju Nat'l. Univ., Jeju, Korea (2013)
Huang NK, Xiong Q, Liu YG, Wang DZ, J.Korean Vacc. Sci. & Tech. JKVST., 6(1), 46 (2002)
http://srdata.nist.gov/xps/selEnergyType.aspx.

[Referenced By]

[Related Articles]

[1] Lee KH, Cho SC, Jo SY, Uhm HS, J. Korean Phys.Soc., 53(2), 631 (2008)

[2] Jo SY, Cho SC, Lee KH, Uhm HS, J. Korean Phys. Soc., 53(2), 641 (2008)

[3] Topala I, Asandulesa M, Spridon D, Dumitrascu N, IEEE Trans. Plasma Sci., 37(6), 946 (2009)

[4] Kim JH, Yang WY, Hahn YB, Korean Chem. Eng. Res., 49(3), 357 (2011)

[5] Kakiuchi H, Ohmi H, Yamada T, Yokoyama K, Okamura K, Yasutake K, Plasma Chem. Plasma Process., 32(3), 533 (2012)

[6] Fang J, Huang Y, Li X, Dou X, J. Raman Spectrosc., 35, 914 (2004)

[7] Vogelsang A, Ohl A, Foest R, Schrder K, Weltmann KD, J. Phys. D: Appl. Phys., 43, 485201 (2010)

[8] Mok YS, Jo JO, Whitehead JC, Chem. Eng. J., 142(1), 56 (2008)

[9] Qiao Y, Zhang X, Ye X, Chen Y, Guo H, J. Rare Earths., 27(2), 323 (2009)

[10] Garbassi F, Morra M, Occhiello E, Polymer Surface from Physics to Technology, John Willey & Sons, 301 (1994)

[11] Kim JM, Park JK, Kim KN, Lee SJ, Kim CH, Jang HG, J. Korea Chem. Soc., 50(3), 237 (2006)

[12] Seo JH, “The Surface Modification of Phosphors by Coating with Nano-oxide,” Thesis, Kyungpook Nat’l. Univ., Daegu, Korea (2009)

[13] Ko RY, “Synthesis of Sr2SiO4:Eu2+ Phosphors with Nonthermal Plasma Discharge,” Thesis, Jeju Nat'l. Univ., Jeju, Korea (2013)

[14] Huang NK, Xiong Q, Liu YG, Wang DZ, J.Korean Vacc. Sci. & Tech. JKVST., 6(1), 46 (2002)

[15] http://srdata.nist.gov/xps/selEnergyType.aspx.