Color Shift Modeling of Light-Emitting Diode Lamps in Step-Loaded Stress Testing

Cai, Miao; Yang, Daoguo; Huang, Jianlin; Zhang, Maofen; Chen, Xianping; Liang, Caihang; Koh, Sau; Zhang, Guoqi

doi:10.1109/jphot.2016.2634702

Cited by 7 publications

(3 citation statements)

References 37 publications

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“…Values of Y/B are also shown in Figure 3b-d. Changes of Y/B are estimated as 2.0%, 4.3%, and 5.6% for CSA-1, CSA-2, and CSA-3, respectively. They imply that PCE slightly decreases after aging, because of the wavelength shift of blue LED chips after 3840 h aging [28]. The higher the aging current becomes, the more decrease PCE exhibits.…”

Section: Experimental Methodologymentioning

confidence: 98%

Multi-Azimuth Failure Mechanisms in Phosphor-Coated White LEDs by Current Aging Stresses

Peng

Guo

et al. 2018

Applied Sciences

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We have experimentally analyzed multi-azimuth degradation mechanisms that govern failures of commercially-available high-power (1 Watt) phosphor-coated white (hppc-W) light-emitting diodes (LEDs) covered with peanut-shaped lenses under three current-stress aging (CSA) conditions. Comprehensive analyses focus on photometric, chromatic, electrical, thermal and packaging characteristics. At the packaging level, (a) the decrease of the phosphor-conversion efficiency; (b) the yellow-browning of the optical lens; and (c) the darkening of the silver-coated reflective layer deposited with extraneous chemical elements (e.g., C, O, Si, Mg, and Cu, respectively) contribute collectively to the integral degradation of the optical power. By contrast, Ohmic contacts, thermal properties, and angles of maximum intensity remain unchanged after 3840 h aging in three cases. Particularly at the chip level, the formation of point defects increases the number of non-radiative recombination centers, and thus decreases the optical power during aging stages. Nevertheless, in view of the change of the ideality factor, the Mg dopant activation and the annealing effect facilitate the increase of the optical power in two specific aging stages (192 h~384 h and 768 h~1536 h). This work offers a systematic guidance for the development of reliable LED-based light sources in general-lighting areas.

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Section: Experimental Methodologymentioning

confidence: 98%

Multi-Azimuth Failure Mechanisms in Phosphor-Coated White LEDs by Current Aging Stresses

Peng

Guo

et al. 2018

Applied Sciences

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“…Therefore, next-generation wLEDs must not only be economical and highly efficient but also meet several other requirements, including health concerns, comfort, high light-color quality, low-frequency flashing, and high reliability. [3][4][5] Full-spectrum wLEDs with a high color-rendering index (CRI) offer great potential in indoor lighting, medical, and health lighting, plant lighting, automobiles, and other applications, making them an important development direction for solid-state lighting. LEDs utilizing phosphor materials are also known as phosphor-converted white LEDs (pc-wLEDs).…”

Section: Introductionmentioning

confidence: 99%

Revealing The Degradation Mechanism of (Sr,Ca)AlSiN₃:Eu²⁺ Phosphor Aged Under Thermal‐Moisture‐Sulfur Conditions: A Combined Experimental and Ab Initio Study

Guo,

Wen,

Tang

et al. 2024

Laser & Photonics Reviews

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MAlSiN3:Eu2+ (M = Ca, Sr) is commonly used in high‐power phosphor‐converted white‐light‐emitting diodes and laser diodes to promote their color‐rendering index. However, the wide application of this phosphor is limited by the degradation of its luminescent properties in high‐temperature, high‐humidity, and high‐sulfur‐content environment. Here, the degradation mechanism of the (Sr,Ca)AlSiN3:Eu2+ (SCASN) red phosphor under thermal‐moisture‐sulfur coupling conditions is investigated. Furthermore, by performing first‐principles calculations, the hydrolysis mechanism on an atomic scale is assessed. The adsorption energy (Eads) and charge transfer (ΔQ) results showed that H2O chemically adsorbed on the (0 1 0), (3 1 0), and (0 0 1) surfaces of the CaAlSiN3 (CASN) host lattice. The energy barrier for H2O dissociation is only 29.73 kJ mol−1 on the CASN (0 1 0) surface, indicating a high dissociation probability. The formation of NH3, Ca(OH)2, and CaAl2Si2O8 is confirmed by H+ tended to combine with surface N atoms, while OH− combined with the surface Al/Si or Ca atoms. Moreover, ab initio molecular dynamics simulations were performed to further understand the hydrolysis process. This work offers a guidance on the design and applications of luminescent materials in LED packages with higher reliability and stability requirements in harsh environment.

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“…Recently, C. Qian et al proposed a method to decompose the SPD of LED lamp with the asymmetric Gaussian model and predict the lumen maintenance and color coordinates by estimating the features of the proposed statistical model [ 18 ] and also used two asymmetric double sigmoidal (Asym2sig) models, representing the blue light and phosphor converted light peaks respectively, to predict the photometric and colorimetric characteristics of a pc-WLED [ 19 ]. The color coordinate shift of LED lamps aged under accelerated ageing tests was investigated by M. Cai et al, [ 20 ] and a power model was proposed to predict the color shift process of LED products. However, as reviewed, few of the current studies on SPDs can combine the failure mechanism analysis and residual color lifetime prediction together to assess the reliability of pc-WLEDs during degradation testing.…”

Section: Introductionmentioning

confidence: 99%

Color Shift Failure Prediction for Phosphor-Converted White LEDs by Modeling Features of Spectral Power Distribution with a Nonlinear Filter Approach

et al. 2017

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With the expanding application of light-emitting diodes (LEDs), the color quality of white LEDs has attracted much attention in several color-sensitive application fields, such as museum lighting, healthcare lighting and displays. Reliability concerns for white LEDs are changing from the luminous efficiency to color quality. However, most of the current available research on the reliability of LEDs is still focused on luminous flux depreciation rather than color shift failure. The spectral power distribution (SPD), defined as the radiant power distribution emitted by a light source at a range of visible wavelength, contains the most fundamental luminescence mechanisms of a light source. SPD is used as the quantitative inference of an LED’s optical characteristics, including color coordinates that are widely used to represent the color shift process. Thus, to model the color shift failure of white LEDs during aging, this paper first extracts the features of an SPD, representing the characteristics of blue LED chips and phosphors, by multi-peak curve-fitting and modeling them with statistical functions. Then, because the shift processes of extracted features in aged LEDs are always nonlinear, a nonlinear state-space model is then developed to predict the color shift failure time within a self-adaptive particle filter framework. The results show that: (1) the failure mechanisms of LEDs can be identified by analyzing the extracted features of SPD with statistical curve-fitting and (2) the developed method can dynamically and accurately predict the color coordinates, correlated color temperatures (CCTs), and color rendering indexes (CRIs) of phosphor-converted (pc)-white LEDs, and also can estimate the residual color life.

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Color Shift Modeling of Light-Emitting Diode Lamps in Step-Loaded Stress Testing

Cited by 7 publications

References 37 publications

Multi-Azimuth Failure Mechanisms in Phosphor-Coated White LEDs by Current Aging Stresses

Multi-Azimuth Failure Mechanisms in Phosphor-Coated White LEDs by Current Aging Stresses

Revealing The Degradation Mechanism of (Sr,Ca)AlSiN₃:Eu²⁺ Phosphor Aged Under Thermal‐Moisture‐Sulfur Conditions: A Combined Experimental and Ab Initio Study

Color Shift Failure Prediction for Phosphor-Converted White LEDs by Modeling Features of Spectral Power Distribution with a Nonlinear Filter Approach

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Color Shift Modeling of Light-Emitting Diode Lamps in Step-Loaded Stress Testing

Cited by 7 publications

References 37 publications

Multi-Azimuth Failure Mechanisms in Phosphor-Coated White LEDs by Current Aging Stresses

Multi-Azimuth Failure Mechanisms in Phosphor-Coated White LEDs by Current Aging Stresses

Revealing The Degradation Mechanism of (Sr,Ca)AlSiN3:Eu2+ Phosphor Aged Under Thermal‐Moisture‐Sulfur Conditions: A Combined Experimental and Ab Initio Study

Color Shift Failure Prediction for Phosphor-Converted White LEDs by Modeling Features of Spectral Power Distribution with a Nonlinear Filter Approach

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Revealing The Degradation Mechanism of (Sr,Ca)AlSiN₃:Eu²⁺ Phosphor Aged Under Thermal‐Moisture‐Sulfur Conditions: A Combined Experimental and Ab Initio Study