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Novel high refractive index, thermal...

Hutchison, Richard Stephen.

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Novel high refractive index, thermally conductive additives for high brightness white LEDs.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Novel high refractive index, thermally conductive additives for high brightness white LEDs./
Author:	Hutchison, Richard Stephen.
Description:	74 p.
Notes:	Source: Masters Abstracts International, Volume: 55-02.
Contained By:	Masters Abstracts International55-02(E).
Subject:	Nanotechnology. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=1602213
ISBN:	9781339160054

Novel high refractive index, thermally conductive additives for high brightness white LEDs.
Hutchison, Richard Stephen.

Novel high refractive index, thermally conductive additives for high brightness white LEDs. - 74 p.

Source: Masters Abstracts International, Volume: 55-02.

Thesis (M.S.)--Rensselaer Polytechnic Institute, 2015.

In prior works the inclusion of nanoparticle fillers has typically been shown to increase the thermal conductivity or refractive index of polymer nanocomposites separately. High refractive index zirconia nanoparticles have already proved their merit in increasing the optical efficiency of encapsulated light emitting diodes. However, the thermal properties of zirconia-silicone nanocomposites have yet to be investigated. While phosphor-converted light emitting diodes are at the forefront of solid-state lighting technologies for producing white light, they are plagued by efficiency losses due to excessive heating at the semiconductor die and in and around the phosphor particles, as well as photon scattering losses in the phosphor layer. It would then be of great interest if the high refractive index nanoparticles were found to both be capable of increasing the refractive index, thus reducing the optical scattering, and also the thermal conductivity, channeling more heat away from the LED die and phosphors, mitigating efficiency losses from heat.

ISBN: 9781339160054Subjects--Topical Terms:

526235
Nanotechnology.

Novel high refractive index, thermally conductive additives for high brightness white LEDs.
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020 $a 9781339160054
035 $a (MiAaPQ)AAI1602213
035 $a AAI1602213
040 $a MiAaPQ $c MiAaPQ
100 1 $a Hutchison, Richard Stephen. $3 3183634
245 1 0 $a Novel high refractive index, thermally conductive additives for high brightness white LEDs.
300 $a 74 p.
500 $a Source: Masters Abstracts International, Volume: 55-02.
500 $a Adviser: Linda Schadler.
502 $a Thesis (M.S.)--Rensselaer Polytechnic Institute, 2015.
520 $a In prior works the inclusion of nanoparticle fillers has typically been shown to increase the thermal conductivity or refractive index of polymer nanocomposites separately. High refractive index zirconia nanoparticles have already proved their merit in increasing the optical efficiency of encapsulated light emitting diodes. However, the thermal properties of zirconia-silicone nanocomposites have yet to be investigated. While phosphor-converted light emitting diodes are at the forefront of solid-state lighting technologies for producing white light, they are plagued by efficiency losses due to excessive heating at the semiconductor die and in and around the phosphor particles, as well as photon scattering losses in the phosphor layer. It would then be of great interest if the high refractive index nanoparticles were found to both be capable of increasing the refractive index, thus reducing the optical scattering, and also the thermal conductivity, channeling more heat away from the LED die and phosphors, mitigating efficiency losses from heat.
520 $a Thermal conductance measurements on unfilled and nanoparticle loaded silicone samples were conducted to quantify the effect of the zirconia nanoparticle loading on silicone nanocomposite thermal conductivity. An increase in thermal conductivity from 0.27 W/mK to 0.49 W/mK from base silicone to silicone with 33.5 wt% zirconia nanoparticles was observed. This trend closely mirrored a basic rule of mixtures prediction, implying a further enhancement in thermal conductivity could be achieved at higher nanoparticle loadings.
520 $a The optical properties of transparency and light extraction efficiency of these composites were also investigated. While overall the zirconia nanocomposite showed good transparency, there was a slight decrease at the shorter wavelengths with increasing zirconia content. For longer wavelength LEDs, such as green or red, this might not matter, but phosphor-converted white LEDs use a blue LED as the photon source making this decrease in transparency important to note. This decrease in transparency may be partially or wholly why a decrease in light extraction efficiency is observed at the 33.5 wt% zirconia loading fraction used for the LED samples.
520 $a Preliminary aging studies under full and enhanced power conditions were conducted over 500 and 1000 hours to observe any changes in the spectral output power and phosphor conversion efficiency of the LEDs due to inclusion of the zirconia nanoparticles. It was found that the nanoparticles have no negative effect on the aging properties but also show no enhancement in relative output power over a preliminary aging study. However, their inclusion did result in increased phosphor conversion efficiency over the use of an unfilled silicone. This increase was seen as around a 10% or greater enhancement for the nanocomposite over that for the base Sylgard silicone.
520 $a These experiments were originally conducted on the commercially available methylated Sylgard 184 silicone and then again on a higher refractive index methyl-phenyl silicone from Momentive. While some of the results from the Momentive silicone were perplexing, it was seen that, even without the inclusion of nanoparticles, the Momentive silicone had a higher refractive index, better aging properties, and a higher phosphor conversion efficiency over 500 hours under enhanced power conditions, warranting further studies into methyl-phenyl silicone nanocomposites.
590 $a School code: 0185.
650 4 $a Nanotechnology. $3 526235
650 4 $a Optics. $3 517925
650 4 $a Materials science. $3 543314
690 $a 0652
690 $a 0752
690 $a 0794
710 2 $a Rensselaer Polytechnic Institute. $b Materials Engineering. $3 3178466
773 0 $t Masters Abstracts International $g 55-02(E).
790 $a 0185
791 $a M.S.
792 $a 2015
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=1602213