Impact of mesh-like top p-electrode on output performance of light-emitting diode: Numerical study

Author(s):  
Yohei Nishidate ◽  
Julia Kholopova ◽  
Evgeny Polushkin ◽  
Irina Khmyrova ◽  
Sergei Shapoval
2020 ◽  
pp. 147715352097693
Author(s):  
AN Padmasali ◽  
SG Kini

Light-emitting diode is the most dominant lighting technology, and lumen output performance is dependent on junction temperature and operating drive current. An experimental analysis is performed to study the thermal and drive current effect on lumen output, and an empirical model is developed to determine the optimum operating conditions of temperature and drive current so as to obtain a maximum lumen output profile. Three commercially available light-emitting diode down-lighter’s light-emitting diodes are chosen for the study. The investigation reveals that there exists an optimum drive current at which lumen output is maximum, and it has a linear relation with junction temperature. Pulse-soak testing was performed to study the deviations of pulsed and continuous operation of drive current to understand the performance of light-emitting diodes. The work helps light-emitting diode luminaire manufacturers to design a controlled power electronic circuit so as to maximize the lumen output effectively and accurately.


2014 ◽  
Vol 22 (18) ◽  
pp. 21454 ◽  
Author(s):  
Dae-Woo Jeon ◽  
Lee-Woon Jang ◽  
Han-Su Cho ◽  
Kyeong-Seob Kwon ◽  
Myeong-Ji Dong ◽  
...  

Author(s):  
António M. G. Lopes ◽  
Vítor A. F. Costa

Abstract A numerical study is conducted concerning the improvement of radial plane fins heat sinks for natural convection cooling of light-emitting diode (LED) lamps. The main objective is to maintain the temperature of the heat sink base below a prescribed threshold for a given released heat flux at the heat sink, minimizing its mass and maintaining at a reasonably simple level the manufacturing processes and operations required for its production. Starting from a previously optimized heat sink for the same purpose, constituted by complete rectangular radial plane fins, the present study aims at further improvements by considering incomplete rectangular radial plane fins. The main objective of this study is to find the best profile for the turning operation to obtain the radial plane fins lighter configuration. It is found that this can be achieved by removing part of the upper internal corners of the rectangular fins, more specifically shaping a curved cut, leading to heat sink mass reduction up to 32.4%. The geometry of the improved heat sink is of cylindrical nature, obtained from cutting an aluminum extruded bar comprising a cylindrical central core and a number of uniformly distributed rectangular radial plane fins, followed by a simple turning operation to remove their upper internal corners. Even if results concern a particular LED lamp, the main ideas and approach prevail to improve other types of heat sinks for general light and/or electronic components cooling.


Author(s):  
Pezhman Sheykholeslami-Nasab ◽  
Mahdi Davoudi-Darareh ◽  
Mohammad Hassan Yousefi

In this study, a model for numerical simulation of carrier transport mechanism in the hybrid quantum dot light-emitting diodes (QD-LEDs) is presented. The carrier mobility in the polymer layer doped with quantum dots (QDs) was calculated by a proposed hopping mobility, which is a concentration-dependent mobility model based on the Gaussian distribution of density-of-states and the effective transport energy models. A QD-LED structure based on PVK:CdSe-QDs blend as the emissive layer with different QD concentrations were fabricated and their current density versus voltage (J-V) characteristic were measured. The numerical results were compared with experimental data, which indicates the ability of the proposed mobility model to describe the general trend of the electrical characteristics of the devices. Then, the exciton density profiles of the devices were extracted based on the continuity equation for singlet and triplet excitons, and the corresponding luminance characteristics of the devices were calculated. The results of the electrical and optical characteristics show that there is an optimal concentration for the QDs in the emissive layer of the QD-LEDs.


2016 ◽  
Vol 23 (5) ◽  
pp. 798-805 ◽  
Author(s):  
Yohei Nishidate ◽  
Irina Khmyrova ◽  
Julia Kholopova ◽  
Evgeny Polushkin ◽  
Bogdan Shevchenko ◽  
...  

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