Implications of phosphor coating on the thermal characteristics of phosphor-converted white LEDs

Law, T. K. and Lim, Fannon and Li, Yun and Yeong, K. K. George and Sng, G. K. Ernest and Uvarajan, M. V. and Teo, J. W. Ronnie (2016) Implications of phosphor coating on the thermal characteristics of phosphor-converted white LEDs. IEEE Transactions on Device and Materials Reliability, 16 (4). pp. 576-582. ISSN 1530-4388 (https://doi.org/10.1109/TDMR.2016.2605059)

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Abstract

The phosphor layer in phosphor-converted white light-emitting diodes (pcLEDs) affects their optical and thermal performances. This paper reports the effects of phosphor thickness and particle concentration on the optical efficiency and temperature rise on conformal phosphor-coated LED package. It is observed that a thicker phosphor layer and a higher phosphor particle concentration will increase the amount of backscattering and back reflection of light from the phosphor layer. These light extraction losses not only reduce the optical efficiency of the light output but also cause heat accumulation in the phosphor layer, leading to higher LED junction temperature. At 2700-K correlated color temperature (CCT), the temperature rise is observed to increase by as much as 2.6 times as compared with its blue LED package. However, the self-heating effect can be reduced through its die-bonding configuration. Structure function-based thermal evaluation shows heat accumulation in the phosphor layer and that flip-chip bonding can dissipate heat generated in the GaN LED and phosphor layer effectively. Evidence in this study demonstrates that optical efficiency and thermal resistance of pcLEDs are dependent on the CCT ratings.

  • Item type:Article
    ID code:65135
    Dates:
    Date
    Event
    31 December 2016
    Published
    31 August 2016
    Published Online
    29 August 2016
    Accepted
    Notes:© 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.
    Subjects:Technology > Electrical engineering. Electronics Nuclear engineering
    Department:Faculty of Engineering
    Depositing user: Pure Administrator
    Date deposited:13 Aug 2018 09:38
    Last modified:11 Apr 2024 01:32
    Related URLs:
    URI:https://strathprints.strath.ac.uk/id/eprint/65135
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