Analysis and Reliability Study of Luminescent Materials for White Lighting

Proceedings

Meneghini, Matteo¹  Trivellin, Nicola²  Buffolo, Matteo³ 

[1] Author to whom correspondence should be addressed.;Department of Information engineering, University of Padova, via Gradenigo 6B, 35131 Padova (PD), Italy;Presented at the 3rd International Electronic Conference on Materials Sciences, 14–28 May 2018. Available online: https://sciforum.net/conference/ecms2018

关键词: phosphor;    lighting;    LED;    laser;   

DOI  :  10.3390/ecms2018-05233

学科分类：社会科学、人文和艺术（综合）

来源: mdpi

【 摘 要 】

In this work, we report on the characterization and reliability/stability study of phosphorescent materials for lighting applications. More specifically, we investigated (a) phosphors directly deposited over light-emitting diodes (LED) chip, (b) remote phosphor (RP) solutions encapsulated in plastic medium for LED lighting, and (c) phosphors without binder for extreme high-intensity laser diode white lighting. The optical and thermal properties of phosphors were studied to develop a sample based on a mix of phosphor compounds in order to achieve different correlated color temperatures (CCT) and high color rendering index (CRI) LEDs. Thermal properties of cerium-doped YAG (Yttrium Aluminum Garnet) phosphor materials were evaluated in order to study thermal quenching. A maximum phosphor operating temperature of 190–200 °C was found to cause a sensible efficiency degeneration. Reduced efficiency and Stokes shift also caused a localized temperature increase in the photoluminescent materials. In the case of remote phosphors, heat did not find a low thermal resistance path to the heatsink (as occurred through the GaN LED chip for direct phosphor-converted devices) and thermal analysis indicated that material temperature might therefore increase to values in excess of 60 °C when a radiation of 435 mW/cm2 hit the sample template. Reliability was also investigated for both plastic-encapsulated materials and binder-free depositions. Pure thermal reliability study indicated that phosphors encapsulated in polycarbonate material were stable up to temperature of approximately 100 °C, while binder-free phosphor did not show any sensible degradation up to temperatures of 525 °C.

【 授权许可】

CC BY