Thermal Analysis and Optimization of Light-Emitting Diodes Filament Lamp

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Jie Liu ◽  
Jinglong Zou ◽  
Sheng Liu
Keyword(s):  
Thermal Analysis ◽  
Heat Dissipation ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Optimization Methods ◽  
Junction Temperature ◽  
Phosphor Layer ◽  
Light Emitting ◽  
Filament Lamp ◽  
Filament Lamps

Abstract Due to the high efficiency, light-emitting diodes (LED) filament lamps have become more and more popular alternative to the incandescent lamp. However, the heat generated by the LED chips is traditionally dissipated by relying on the natural convection within lamps, resulting in poor heat dissipation performance for LED filament lamps. A numerical simulation model of the typical LED filament lamp was established to simulate and analyze the heat dissipation and airflow phenomenon of LED filament lamps in this study. In addition, increasing lamp sizes, increasing phosphor diameters, and using finned phosphor layers were considered as optimization measures to improve the heat dissipation performance of LED filament lamps. When these optimization measures are applied, chip junction temperatures are reduced. A reduction of 6.9 °C is seen when the lamp radius is increased from 25 mm to 31 mm. When the phosphor diameter is increased to 4 mm from 2 mm, the junction temperature is reduced by 17.2 °C. Integration of a finned phosphor layer where there are 12 fins at a height of 1 mm and thickness of 0.2 mm in the layer decreased the junction temperature by 10.9 °C. These optimization results provide technical support for the design and manufacture of LED filament lamps, and thermal analysis results provide theoretical support for the promotion of these optimization methods.

scholarly journals Effect of Dielectric Distributed Bragg Reflector on Electrical and Optical Properties of GaN-Based Flip-Chip Light-Emitting Diodes

Micromachines ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 650 ◽  
Author(s):  
Shengjun Zhou ◽  
Haohao Xu ◽  
Mengling Liu ◽  
Xingtong Liu ◽  
Jie Zhao ◽  
...  
Keyword(s):  
Flip Chip ◽  
Heat Dissipation ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Incident Angle ◽  
Light Output ◽  
Bragg Reflector ◽  
Distributed Bragg Reflector ◽  
Light Emitting ◽  
Via Hole

We demonstrated two types of GaN-based flip-chip light-emitting diodes (FCLEDs) with distributed Bragg reflector (DBR) and without DBR to investigate the effect of dielectric TiO2/SiO2 DBR on optical and electrical characteristics of FCLEDs. The reflector consisting of two single TiO2/SiO2 DBR stacks optimized for different central wavelengths demonstrates a broader reflectance bandwidth and a less dependence of reflectance on the incident angle of light. As a result, the light output power (LOP) of FCLED with DBR shows 25.3% higher than that of FCLED without DBR at 150 mA. However, due to the better heat dissipation of FCLED without DBR, it was found that the light output saturation current shifted from 268 A/cm2 for FCLED with DBR to 296 A/cm2 for FCLED without DBR. We found that the use of via-hole-based n-type contacts can spread injection current uniformly over the entire active emitting region. Our study paves the way for application of DBR and via-hole-based n-type contact in high-efficiency FCLEDs.

scholarly journals Optimization of Helium Inflating on Heat Dissipation and Luminescence Properties of the A60 LED Filament Lamps

2019 ◽  
Vol 2019 ◽  
pp. 1-5
Author(s):  
Yizhan Chen ◽  
Qingguang Zeng ◽  
Lite Zhao ◽  
Yuanxing Li ◽  
Guangyao Huang ◽  
...  
Keyword(s):  
Heat Dissipation ◽  
Cost Effective ◽  
High Heat ◽  
Luminous Flux ◽  
Junction Temperature ◽  
Color Temperature ◽  
Filament Lamp ◽  
High Heat Transfer ◽  
High Heat Transfer Coefficient ◽  
Filament Lamps

LED filament lamp has the characteristics of nearly 360° lighting angle, high brightness, and low energy consumption, turning it gradually into the best substitute for traditional incandescent lamps. At present, due to the limitations of heat dissipation, the development of high-power LED filament lamp is restricted. Helium is a rare gas with small density and high heat transfer coefficient. It can be used as a cooling and protective gas for LED filament lamp. In this paper, we investigated the effects of helium on the heat dissipation and luminescence performance of the A60 LED filament lamps by detecting the changes of junction temperature, color temperature, and luminous flux of different ratios helium inflating in the different power A60 LED filament lamps. Through the experiment, we found the most cost-effective ratio of helium gas in the A60 LED filament lamps without improving the lamp size and the filament diameter.

High-efficiency, long-lifetime deep-blue organic light-emitting diodes

2021 ◽  
Vol 15 (3) ◽  
pp. 208-215 ◽  
Author(s):  
Soon Ok Jeon ◽  
Kyung Hyung Lee ◽  
Jong Soo Kim ◽  
Soo-Ghang Ihn ◽  
Yeon Sook Chung ◽  
...  
Keyword(s):  
High Efficiency ◽  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Deep Blue ◽  
Organic Light ◽  
Long Lifetime

scholarly journals High efficiency blue organic light-emitting diodes with below-bandgap electroluminescence

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Maria Vasilopoulou ◽  
Abd. Rashid bin Mohd Yusoff ◽  
Matyas Daboczi ◽  
Julio Conforto ◽  
Anderson Emanuel Ximim Gavim ◽  
...  
Keyword(s):  
High Efficiency ◽  
Light Emitting Diodes ◽  
High Mobility ◽  
Organic Light Emitting Diodes ◽  
Triplet Energy ◽  
Material Interface ◽  
Light Emitting ◽  
Thermally Activated ◽  
Organic Light ◽  
Hole Transporting

AbstractBlue organic light-emitting diodes require high triplet interlayer materials, which induce large energetic barriers at the interfaces resulting in high device voltages and reduced efficiencies. Here, we alleviate this issue by designing a low triplet energy hole transporting interlayer with high mobility, combined with an interface exciplex that confines excitons at the emissive layer/electron transporting material interface. As a result, blue thermally activated delay fluorescent organic light-emitting diodes with a below-bandgap turn-on voltage of 2.5 V and an external quantum efficiency (EQE) of 41.2% were successfully fabricated. These devices also showed suppressed efficiency roll-off maintaining an EQE of 34.8% at 1000 cd m−2. Our approach paves the way for further progress through exploring alternative device engineering approaches instead of only focusing on the demanding synthesis of organic compounds with complex structures.

A Technique for the Direct Measurement of the Junction Temperature in Power Light Emitting Diodes

2020 ◽  
pp. 1-1
Author(s):  
Demetrio Iero ◽  
Massimo Merenda ◽  
Sonia Polimeni ◽  
Riccardo Carotenuto ◽  
Francesco G. Della Corte
Keyword(s):  
Direct Measurement ◽  
Light Emitting Diodes ◽  
Junction Temperature ◽  
Light Emitting

scholarly journals Efficient and large-area all vacuum-deposited perovskite light-emitting diodes via spatial confinement

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Peipei Du ◽  
Jinghui Li ◽  
Liang Wang ◽  
Liang Sun ◽  
Xi Wang ◽  
...  
Keyword(s):  
High Resolution ◽  
Large Scale ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Scale Production ◽  
Nonradiative Recombination ◽  
Large Area ◽  
Spatial Confinement ◽  
Light Emitting ◽  
Large Scale Production

AbstractWith rapid advances of perovskite light-emitting diodes (PeLEDs), the large-scale fabrication of patterned PeLEDs towards display panels is of increasing importance. However, most state-of-the-art PeLEDs are fabricated by solution-processed techniques, which are difficult to simultaneously achieve high-resolution pixels and large-scale production. To this end, we construct efficient CsPbBr3 PeLEDs employing a vacuum deposition technique, which has been demonstrated as the most successful route for commercial organic LED displays. By carefully controlling the strength of the spatial confinement in CsPbBr3 film, its radiative recombination is greatly enhanced while the nonradiative recombination is suppressed. As a result, the external quantum efficiency (EQE) of thermally evaporated PeLED reaches 8.0%, a record for vacuum processed PeLEDs. Benefitting from the excellent uniformity and scalability of the thermal evaporation, we demonstrate PeLED with a functional area up to 40.2 cm2 and a peak EQE of 7.1%, representing one of the most efficient large-area PeLEDs. We further achieve high-resolution patterned perovskite film with 100 μm pixels using fine metal masks, laying the foundation for potential display applications. We believe the strategy of confinement strength regulation in thermally evaporated perovskites provides an effective way to process high-efficiency and large-area PeLEDs towards commercial display panels.

Sign in / Sign up

Export Citation Format

Share Document