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LED junction temperature measurement using generated photocurrent.

Lock, D A*; Hall, S R G; Prins, A D*; Crutchley, B G*; Kynaston, S*; Sweeney, S J* (2013) LED junction temperature measurement using generated photocurrent. J. Display Technol., 9 (5). pp. 396-401.

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LED based lamps on the market today are expensive due to the complex packaging required to dissipate the heat generated. This also limits their performance and lifetime due to degradation of the phosphor or individual LED chips in the case of RGB sources. There is a strong commercial imperative to develop in-situ technology to measure, and ultimately compensate for the thermal environment of a luminaire.
Utilising the large Stoke's shift In GaN green and blue emitting LEDs, a blue LED emitter pump can induce a photocurrent within the both green and blue devices. Measurements have shown that we can excite both the green and blue emitters on the absorption edge resulting in a rise in open circuit voltage (Voc) with increasing temperature. From these measurements we have been able to plot the junction temperature of a device in quasi-cw mode at 80 mA resulting in a junction temperature of 48.2 0C (±) compared to a junction temperature of 51. 2 0C (±) using the forward voltage technique
In the following article we will describe the technique and results achieved in driving a green emitting LED with a blue emitting pump LED and discuss some of the benefits and problems with the technique.

Item Type: Article
Subjects: Optical Radiation and Photonics
Optical Radiation and Photonics > Photometry and Sources
Identification number/DOI: 10.1109/JDT.2013.2251607
Last Modified: 02 Feb 2018 13:14
URI: http://eprintspublications.npl.co.uk/id/eprint/5787

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