Life-time characterization of LEDs

Paisnik, Kristo; Rang, G.; Rang, Toomas

doi:10.3176/eng.2011.3.05

Cited by 10 publications

(5 citation statements)

References 7 publications

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“…As a result, the light output of the light source is equally spread over the inner surface of the sphere and the luminous intensity is the same in every point of the inner surface. This paper considers the further development of our previous work [4]. …”

Section: Motives and Backgroundmentioning

confidence: 99%

Physics related modeling of power LEDs

Paisnik

Poppe

Rang

et al. 2012

2012 13th Biennial Baltic Electronics Conference

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LED technology has evolved at a fast pace within the last years; offering already LED devices with luminous efficacy of 150 lumens per watt or even more. Based on studies about LED light output dependence on forward current and (junction) temperature, the optimal model for simulating the light output of monochromatic LEDs has been developed. Available solutions in literature are analyzed and modified to relate their parameters to LED properties, which could be predicted with a SPICE-like electrical model of LEDs. Experimental blue and red high power LEDs are measured using the state-of-the-art measurement systems -T3Ster and TERALED in a combined measurement setup and optimization algorithms are used for calculating additional fitting parameters for the developed model. The modeled results are compared against the experimental measurements and an excellent agreement is found between the simulated and measured output of monochromatic LEDs.

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Section: Motives and Backgroundmentioning

confidence: 99%

Physics related modeling of power LEDs

Paisnik

Poppe

Rang

et al. 2012

2012 13th Biennial Baltic Electronics Conference

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“…So far, discussions about the durability of LED were mainly driven by the decrease in luminous flux, the so-called lumen maintenance. This has led to the development of a variety of tools, methods and standards for the LED life estimation [12]- [15]. The evaluation of the color shift, on the other hand, has yet been considered only rudimentary in terms of color distance and shift direction.…”

Section: Introductionmentioning

confidence: 99%

Combined Methodology for Accurate Evaluation of Distance and Direction of Chromaticity Shifts in LED Reliability Tests

Benkner

Babilon

Herzog

et al. 2021

IEEE Trans. Device Mater. Relib.

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Light Emitting Diodes are an integral part of modern illumination systems. While their long-term stability in terms of lumen maintenance used to be in the focus leading to drastically increased nominal lifetimes over the past decade, the color shift or respectively chromaticity shift is lately attracting more and more attention especially in lighting applications that demand for a high chromatic stability. Common ways of displaying and reporting color shifts in LEDs and LED products provide only limited possibilities to accuratly classify changes in color according to the current understanding of the underlying degradation processes. This paper therefore presents a methodology to overcome the observed discrepancies in analyzing time-dependent chromaticity data in terms of their shift direction and distance within the CIE 1976 (u , v ) chromaticity diagram. The use of an extrapolation function extending the shift towards the spectral locus enables the determination of the corresponding nearest spectral locus intersection wavelength. Thereby, it is possible to classify changes in color according to different shift regions, which basically allows for performing an automated comprehensive color shift mode analysis. As part of this paper five different algorithmic approaches for determining the intersection wavelength and shift region are discussed and compared in terms of their accuracy and ease in implementation.

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“…In 1955, Rubin Braunstein, who worked at Radio Corporation of America, discovered that some common diodes emit infrared light when connected to a current [30,31]. Also, Rubin Braunstein and Egon Loebner reported in 1958 a green LED which was realized from a lead antimonde/germanium alloy [32].…”

Section: Evolution Of Quantum Dot-based Light-emitting Diodesmentioning

confidence: 99%

“…In 1962, the researcher Nick Holonyak Jr., who is called as "the father of the light-emitting diode," created the first practical visible-spectrum (red) GaAsP LED at General Electric Company in New York [33]. In 1964, IBM introduced the using of LEDs on circuit boards in an early mainframe computer [31].…”

Section: Evolution Of Quantum Dot-based Light-emitting Diodesmentioning

confidence: 99%

Recent Developments in Applications of Quantum-Dot Based Light-Emitting Diodes

Armăşelu¹

2017

Quantum-Dot Based Light-Emitting Diodes

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Quantum dot-based light-emitting diodes (QD-LEDs) represent a form of light-emitting technology and are regarded like a next generation of display technology after the organic light-emitting diodes (OLEDs) display. QD-LEDs are different from liquid crystal displays (LCDs), OLEDs, and plasma displays due to the fact that QD-LEDs present an ideal blend of high brightness, efficiency with long lifetime, flexibility, and low-processing cost of organic LEDs. So, QD-LEDs show theoretical performance limits which surpass all other display technologies. The goal of this chapter is, firstly, to provide a historical prospective study of QD-LEDs applications in display and lighting technologies, secondly, to present the most recent improvements in this field, and finally, to discuss about some current directions in QD-LEDs research that concentrate on the realization of the next-generation displays and high-quality lighting with superior color gamut, higher efficiency, and high color rendering index.

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Life-time characterization of LEDs

Cited by 10 publications

References 7 publications

Physics related modeling of power LEDs

Physics related modeling of power LEDs

Combined Methodology for Accurate Evaluation of Distance and Direction of Chromaticity Shifts in LED Reliability Tests

Recent Developments in Applications of Quantum-Dot Based Light-Emitting Diodes

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