Long-term degradation mechanisms of mid-power LEDs for lighting applications

Buffolo, Matteo; Santi, Carlo De; Meneghini, Matteo; Rigon, Daniele; Meneghesso, Gaudenzio; Zanoni, Enrico

doi:10.1016/j.microrel.2015.06.098

Cited by 38 publications

(20 citation statements)

References 11 publications

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“…In these investigation, silicone degradation was quantitatively evaluated using finite element analysis and used to estimate the LED package lifetime depending on the operation conditions. Buffolo et al [21] present the results of a reliability investigation performed on four different groups of commercially available mid-power white LEDs. Their data gathered all along the 4000 h of stress accumulated suggest the presence of multiple degradation mechanisms that may limit the useful lifespan of the LED packages.…”

Section: Current Agreed Methodsmentioning

confidence: 99%

Lumen maintenance predictions for LED packages

Driel

Schuld²,

Jacobs

et al. 2016

Microelectronics Reliability

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Commercial claims for LED-based products in terms of lumen maintenance are fully based on TM-21 extrapolations using LM-80 data. This paper indicates that there may be a risk in doing this as TM-21 only relies on the behavior of the average LED degradation, instead of taking into account the degradation of all individual LEDs. Therefore, we propose a more profound statistical analysis in order to make the appropriate step from TM-21 extrapolation to lumen maintenance on a product level. This is needed as some commercial claims are based on 10 years of warranty and some service bids provide periods of 20 to 25 years of operation. This paper reviews the different approaches currently available to perform lumen maintenance extrapolations. We propose a new method to analyze and extrapolate LM-80 data using a more profound statistical approach. Highlights The main highlights of the presented research are: • A new statistical method to extrapolate LM-80 data • The method outperforms the currently available ones as it is statistically founded • Five cases were executed and benchmarked with the TM-21 method • A full statistical acceleration model is now available for lifetime assessment of LEDs

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Section: Current Agreed Methodsmentioning

confidence: 99%

Lumen maintenance predictions for LED packages

Driel

Schuld²,

Jacobs

et al. 2016

Microelectronics Reliability

View full text Add to dashboard Cite

show abstract

“…However, when performing optical measurements during the aging, previous works studied the chip under investigation in an integrated manner, in which the light emission of the whole chip is collected via an integrating sphere. It therefore has abandoned the information of possible spatial inhomogeneity along the chip surface [6]. In general, spatially resolved emission spectra can be obtained by a spectroscopy integrated with a transmission electron microscopy [7], scanning near-field microscopy [8], confocal microscopy [9], and atomic force microscopy [10].…”

Section: Introductionmentioning

confidence: 99%

Effect of Carrier Localization and Shockley-Read-Hall Recombination on the Spatial Distribution of Electroluminescence in InGaN LEDs

Peng

Gao

et al. 2018

IEEE Photonics J.

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We investigate divergent behaviors in the emission of blue and green lightemitting diodes (LEDs) when they are subjected to the current-stress aging. Microscopic hyperspectral imaging is introduced to measure spatially resolved mappings of the peak intensity, the peak energy, and the full width at half maximum. Also, plots of external quantum efficiency versus injection current are measured to determine the extent of the Shockley-Read-Hall (SRH) nonradiative recombination rate based on the two-level model. As a result, a phenomenological model is proposed to account for the competitive mechanism between the carrier localization and the SRH recombination. In the blue LED case, the increase in the radiative recombination within localization states cancels the SRH nonradiative recombination within point defects. While in the green LED case, the enhancement of SRH recombination and the remission of carrier localization jointly kill the radiative recombination.

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“…While other studies investigate lumen degradation from primarily qualitative approach [16]- [18], the scarcity of research taking into account the impact of relative humidity specifically and its corresponding association with color degradation is notable. In spite of the fact that the requirement for color consistency has become more important than lumen maintenance in many applications, prediction models involving color shift are limited [19].…”

Section: Introductionmentioning

confidence: 99%

A Practical Degradation Based Method to Predict Long-Term Moisture Incursion and Color Change in High Power LEDs

Law

Lim

2018

IEEE Photonics J.

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The effect of relative humidity on LEDs and how the moisture incursion is associated to the color shift is studied. This paper proposes a different approach to describe the lumen degradation of LEDs due to the long-term effects of humidity. Using the lumen degradation data of different types of LEDs under varying conditions of relative humidity, a humidity based degradation model (HBDM) is developed. A practical estimation method from the degradation behaviour is proposed to quantitatively gauge the effect of moisture incursion by means of a humidity index. This index demonstrates a high correlation with the color shift indicated by the LED's yellow to blue output intensity ratio. Physical analyses of the LEDs provide a qualitative validation of the model, which provides good accuracy with longer periods of moisture exposure. The results demonstrate that the HBDM is an effective indicator to predict the extent of the long-term impact of humidity and associated relative color shift.

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Long-term degradation mechanisms of mid-power LEDs for lighting applications

Cited by 38 publications

References 11 publications

Lumen maintenance predictions for LED packages

Lumen maintenance predictions for LED packages

Effect of Carrier Localization and Shockley-Read-Hall Recombination on the Spatial Distribution of Electroluminescence in InGaN LEDs

A Practical Degradation Based Method to Predict Long-Term Moisture Incursion and Color Change in High Power LEDs

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