LED Junction Temperature Measurement Using Generated Photocurrent

Lock, D.; Hall, Simon R. G.; Prins, A. D.; Crutchley, B. G.; Kynaston, S.; Sweeney, S. J.

doi:10.1109/jdt.2013.2251607

Cited by 15 publications

(9 citation statements)

References 22 publications

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“…The electrons subsequently recombine in the active region and cause photon emissions. We find a carrier recombination temperature which is not consistent with the junction temperature, particularly at higher junction temperatures [6][7][8][9][10][11][12]. This effect is larger than previously noted [10,13].…”

contrasting

confidence: 94%

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Measuring Thermally-Driven LED Emissions via Voltage Modulation near Zero Bias

Orem¹,

Vogt

Graham

et al. 2018

Electronics

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This study was launched to demonstrate that LEDs at zero bias show recombination photon emissions, and to check the models for the same. A method for measuring the light emission for a LED near zero bias is presented. A large reverse bias sufficient to suppress detectable emissions is assumed. The bias voltage between ‘large reverse’ and our target voltage is modulated, and the difference measured. The measured emissions found are consistent with the Shockley diode equation. The spectrum near zero bias can be measured and characterized. It shows LED behavior that is substantially different from other typical measurements, and suggests a violation of Kirchhoff’s Law.

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contrasting

confidence: 94%

“…In Section 3.2, we noted that the high energy tail is not consistent with the measured temperature [6][7][8][9][10][11][12]. For 201 • C, the best fit exponent is roughly 1.4× the measured temperature.…”

Section: Analysis Of Properties Of Recombinationmentioning

confidence: 85%

Measuring Thermally-Driven LED Emissions via Voltage Modulation near Zero Bias

Orem¹,

Vogt

Graham

et al. 2018

Electronics

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show abstract

“…The junction temperature of electronic devices, such as LEDs, has long been studied and measured for the purpose of understanding and improving device performance [31,32]. For LEDs, "junction" refers to the hotspot between p-and n-types of semiconductor that form the active diode and the temperature of the "junction" is typically the highest across the entire device, higher than the exterior temperature of the electronic device during operation.…”

Section: New Life Testing Methodsmentioning

confidence: 99%

Thermal behavior and indirect life test of large-area OLED lighting panels

et al. 2014

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In this work, we studied the thermal behavior and addressed the challenges of life testing of large area OLED devices. In particular, we developed an indirect method to accurately calculate the life time of large-area OLED lighting panels without physically life-testing the panels. Using small area OLEDs with structures identical with the tested panels, we performed the life tests at desired driving current densities at different temperatures and extracted the relationship between junction temperature and the lifetime for the particular device. By measuring the panel junction temperature during operation under the same current density and using the life time measured on small area test devices, we determine the lifetime of the panels based on the thermal dependence. We test this methodology by predicting the life time of white PHOLED panels and then physically testing the panels. The typical result for the lifetime to 80% of the initial luminance (LT80) of the panel at a constant dc current density of 10 mA/cm 2 (3800 cd/m 2 ), was predicted to be 526 hours in good agreement with the actual life-test at 10 mA/cm 2 of 512 hrs. This good agreement, confirmed in different experiments, validates this novel technique as a practical life time predictor of large-area OLED lighting panels in a time saving manner.

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“…cannot be measured directly. Although there are some methods to estimate T J by using temperature-sensitive electrical parameters, considerable implementation efforts are necessary [23], [24]. Therefore, the junction temperature estimation based on the accurate electro-thermal model with the help of updating of field operation conditions is a feasible way to analyze the long-term thermal profiles in this study.…”

Section: Lifetime Models and Degradation Testing Data Analysismentioning

confidence: 99%

A Lifetime Prediction Method for LEDs Considering Real Mission Profiles

Wang

Zhan

et al. 2017

IEEE Trans. Power Electron.

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The Light-Emitting Diode (LED) has become a very promising alternative lighting source with the advantages of longer lifetime and higher efficiency than traditional ones. The lifetime prediction of LEDs is important to guide the LED system designers to fulfill the design specifications and to benchmark the cost-competitiveness of different lighting technologies. However, the existing lifetime data released by LED manufacturers or standard organizations are usually applicable only for some specific temperature and current levels. Significant lifetime discrepancies may be seen in the field operations due to the varying operational and environmental conditions during the entire service time (i.e., mission profiles). To overcome the challenge, this paper proposes an advanced lifetime prediction method, which takes into account the field operation mission profiles and also the statistical properties of the life data available from accelerated degradation testing. The electrical and thermal characteristics of LEDs are measured by a T3Ster system, used for the electrothermal modeling. It also identifies key variables (e.g., heat sink parameters) that can be designed to achieve a specified lifetime and reliability level. Two case studies of an indoor residential lighting and an outdoor street lighting application are presented to demonstrate the prediction procedures and the impact of different mission profiles on the lifetime of LEDs.

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LED Junction Temperature Measurement Using Generated Photocurrent

Cited by 15 publications

References 22 publications

Measuring Thermally-Driven LED Emissions via Voltage Modulation near Zero Bias

Measuring Thermally-Driven LED Emissions via Voltage Modulation near Zero Bias

Thermal behavior and indirect life test of large-area OLED lighting panels

A Lifetime Prediction Method for LEDs Considering Real Mission Profiles

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