Development of optical-thermal coupled model for phosphor-converted LEDs

Qian, Xinglu; Zou, Jun; Shi, Mingming; Yang, Bobo; Li, Yang; Wang, Ziming; Liu, Yiming; Liu, Zizhuan; Zheng, Fei

doi:10.1007/s12200-018-0857-2

Cited by 14 publications

(9 citation statements)

References 65 publications

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“…If we assume that WPE chip = 70% for the LED chip (a typical value for modern blue LEDs under typical operational conditions), then it will mean that up to half of the total thermal power P h for white LED package can be related to the phosphor thermal losses P hD . Similar power ratio results were previously determined in the literature [19,22].…”

Section: Applicability Of the Approach For Leds With Phosphor Light Csupporting

confidence: 91%

“…This makes the required measurements of transfer impedance impossible. The secondary heat sources can be characterized by ray tracing simulations [19][20][21]. Yet this approach requires access to proprietary information, such as phosphor composite particles spatial distribution, excitation and emission spectra, reflection properties, and the angular light distribution of the LED die.…”

Section: Introductionmentioning

confidence: 99%

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Multiple Heat Source Thermal Modeling and Transient Analysis of LEDs

et al. 2019

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Thermal transient testing is widely used for LED characterization, derivation of compact models, and calibration of 3D finite element models. The traditional analysis of transient thermal measurements yields a thermal model for a single heat source. However, it appears that secondary heat sources are typically present in LED packages and significantly limit the model’s precision. In this paper, we reveal inaccuracies of thermal transient measurements interpretation associated with the secondary heat sources related to the light trapped in an optical encapsulant and phosphor light conversion losses. We show that both have a significant impact on the transient response for mid-power LED packages. We present a novel methodology of a derivation and calibration of thermal models for LEDs with multiple heat sources. It can be applied not only to monochromatic LEDs but particularly also to LEDs with phosphor light conversion. The methodology enables a separate characterization of the primary pn junction thermal power source and the secondary heat sources in an LED package.

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Section: Applicability Of the Approach For Leds With Phosphor Light Csupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Multiple Heat Source Thermal Modeling and Transient Analysis of LEDs

et al. 2019

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“…17 Moreover, photothermal conversion can be applied for heat management in light-emitting diodes (LED) to avoid efficiency losses, 18 as the LED lifetime is dramatically dependent on the junction temperature. 19 Nonetheless, we note that it has been poorly explored, as biorelated applications have been the target and the liquid medium is, thus, favored, 20 contrarily to the need of films for optoelectronics. Only a single example reports the use of graphene-based coatings as photothermal converts for salt water desalination, 21 which has no link to optoelectronics; thus, the development of efficient photothermal coatings is an unexplored field with potentially large impact.…”

Section: Introductionmentioning

confidence: 99%

“…Examples include photothermal optical modulation systems, − thermally actuated waveplates, and thermodriven photonic actuators . Moreover, photothermal conversion can be applied for heat management in light-emitting diodes (LED) to avoid efficiency losses, as the LED lifetime is dramatically dependent on the junction temperature . Nonetheless, we note that it has been poorly explored, as biorelated applications have been the target and the liquid medium is, thus, favored, contrarily to the need of films for optoelectronics.…”

Section: Introductionmentioning

confidence: 99%

High-Quantum-Yield Upconverting Er³⁺/Yb³⁺-Organic–Inorganic Hybrid Dual Coatings for Real-Time Temperature Sensing and Photothermal Conversion

et al. 2020

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Flexible coatings with dual capabilities for remote real-time temperature sensing and photothermal conversion have a huge potential in the field of advanced thermal actuated optoelectronic applications. In this work, we demonstrated that plastic free-standing films of Er 3+ /Yb 3+ -codoped GeO 2 −Ta 2 O 5 particles dispersed in poly(methyl methacrylate) (PMMA) having intriguing upconversion high absolute emission quantum yield (∼0.1452, excited at 980 nm, 760 W•cm −2 ) can simultaneously operate as photothermal converters and real-time primary thermometers. The emission of the films was studied at the microscale, revealing emission homogeneity detected through surface hyperspectral microscopy. One factor that contributes to the unusually high absolute emission quantum yield, when compared with other oxides-based materials, is the high occurrence (probability) of the shortest Yb−Er distances obtained when the YbTaO 4 phase is formed. This, as demonstrated by computational simulations of doping processes, favors the Yb-to-Er energy transfer rates, enhancing the population of the Er 3+ emitting levels. Besides, the films combined a relative thermal sensitivity of ∼1.1% K −1 (at 300 K) with a temperature uncertainty of ∼0.7 K and a maximum photothermal efficiency of ∼44%, which permits the prospect of using this material as a coating with photothermal and thermometer functions. Moreover, as an added benefit, the thermal resistance of the composite in PMMA was estimated, yielding a maximum value of 760 ± 8 K•W −1 . This is the first example of an active coating for photothermal conversion with the simultaneous ability to remotely sense temperature that can be explored in NIR-pumped free-space telecommunications without the need of additional optoelectronics devices.

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“…Nowadays, light-emitting diode (LED) has met an extensive application in every aspect of our life. According to some comprehensive studies' conclusions [1][2][3], high LED junction temperature will not reduce the service life of LEDs significantly yet has a negative impact on the optical performance, revealing the great significance of reasonable heat sink design to LED lanterns. Now, extensive research studies have been conducted well and widely, concerning heat sinks of LED lights to improve their cooling performance.…”

Section: Introductionmentioning

confidence: 99%

Graph Theory-Based Mathematical Calculation Modeling for Temperature Distribution of LED Lights’ Convective Cooled Heat Sinks under Moisture Environment

Lyu

Chen

2020

Mathematical Problems in Engineering

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In this paper, a mathematical model based on graph theory is proposed to calculate the heat distribution of LED lights’ convective cooled heat sink. First, the heat and mass transfer process of a single fin under moisture environment is analyzed. Then, the heat transfer process is characterized by a digraph, defining fins and joints of a heat sink as edges and vertices in graph theory. Finally, the whole heat transfer process is described by two criteria achieved based on graph theory. Therefore, the temperature-heat calculation equations of the whole heat sink are deduced. The accuracy of this model is verified by testing the junction temperature of different LED chips mounted on the same heat sink under moisture environment, and the relative errors between the calculated value and the experimental data are all within 5%, and it is also concluded from the model that heat sinks with an identical heat digraph but different types have close cooling performance and are verified by two typical heat sinks, cylindrical heat sink and rectangular plate-fin heat sink, under the same conditions. The mathematical model based on group theory developed in this paper combined with computer technology is convenient for the performance analysis among a large number of heat sink fin arrangement schemes.

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Development of optical-thermal coupled model for phosphor-converted LEDs

Cited by 14 publications

References 65 publications

Multiple Heat Source Thermal Modeling and Transient Analysis of LEDs

Multiple Heat Source Thermal Modeling and Transient Analysis of LEDs

High-Quantum-Yield Upconverting Er³⁺/Yb³⁺-Organic–Inorganic Hybrid Dual Coatings for Real-Time Temperature Sensing and Photothermal Conversion

Graph Theory-Based Mathematical Calculation Modeling for Temperature Distribution of LED Lights’ Convective Cooled Heat Sinks under Moisture Environment

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Development of optical-thermal coupled model for phosphor-converted LEDs

Cited by 14 publications

References 65 publications

Multiple Heat Source Thermal Modeling and Transient Analysis of LEDs

Multiple Heat Source Thermal Modeling and Transient Analysis of LEDs

High-Quantum-Yield Upconverting Er3+/Yb3+-Organic–Inorganic Hybrid Dual Coatings for Real-Time Temperature Sensing and Photothermal Conversion

Graph Theory-Based Mathematical Calculation Modeling for Temperature Distribution of LED Lights’ Convective Cooled Heat Sinks under Moisture Environment

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High-Quantum-Yield Upconverting Er³⁺/Yb³⁺-Organic–Inorganic Hybrid Dual Coatings for Real-Time Temperature Sensing and Photothermal Conversion