scholarly journals Effect of Trapezoidal-Shaped Well on Efficiency Droop in InGaN-Based Double-Heterostructure Light-Emitting Diodes

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Ray-Ming Lin ◽  
Mu-Jen Lai ◽  
Liann-Be Chang ◽  
Chou-Hsiung Huang ◽  
Chang-Ho Chen
Keyword(s):  
Quantum Efficiency ◽  
Current Density ◽  
Light Emitting Diodes ◽  
Internal Quantum Efficiency ◽  
Well Being ◽  
Efficiency Droop ◽  
Maximum Efficiency ◽  
Light Emitting ◽  
Double Heterostructure ◽  
Current Densities

We investigated the effects of different well shapes on the external quantum efficiency (EQE) and the efficiency droop in wide-well InGaN/GaN double-heterostructure light-emitting diodes. For forward current densities in the measurement range of greater than 135 A/cm2, the device featuring a trapezoidal well exhibited improved EQEs and alleviative efficiency droop, relative to those of the device featuring a rectangular well. The decreased Auger loss has been proposed as the main reason for the greater maximum efficiency that occurred at high current density (>50 A/cm2). For the devices incorporating trapezoidal and rectangular wells, the EQEs at 200 A/cm2decreased by 14 and 40%, respectively, from their maximum values, resulting in the EQE at a current density of 200 A/cm2of the device featuring a trapezoidal well being 17.5% greater than that featuring a rectangular well. These results suggest that, in addition to the decreased Auger loss, the alleviation in efficiency droop at higher current densities might be due to higher internal quantum efficiency resulted from the improved carrier injection efficiency of the trapezoidal well.

Perovskite Light‐Emitting Diodes with Near Unit Internal Quantum Efficiency at Low Temperatures

2021 ◽  
Vol 33 (14) ◽  
pp. 2006302
Author(s):  
Yarong He ◽  
Jiaxu Yan ◽  
Lei Xu ◽  
Bangmin Zhang ◽  
Qian Cheng ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
Low Temperatures ◽  
Light Emitting Diodes ◽  
Internal Quantum Efficiency ◽  
Light Emitting

scholarly journals Temperature-Dependent Internal Quantum Efficiency of Blue High-Brightness Light-Emitting Diodes

2014 ◽  
Vol 50 (11) ◽  
pp. 911-920 ◽  
Author(s):  
Ilya E. Titkov ◽  
Sergey Yu. Karpov ◽  
Amit Yadav ◽  
Vera L. Zerova ◽  
Modestas Zulonas ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
Light Emitting Diodes ◽  
Internal Quantum Efficiency ◽  
Temperature Dependent ◽  
High Brightness ◽  
Light Emitting

Internal quantum efficiency of highly-efficient InxGa1−xN-based near-ultraviolet light-emitting diodes

2003 ◽  
Vol 83 (24) ◽  
pp. 4906-4908 ◽  
Author(s):  
Satoshi Watanabe ◽  
Norihide Yamada ◽  
Masakazu Nagashima ◽  
Yusuke Ueki ◽  
Chiharu Sasaki ◽  
...  
Keyword(s):  
Ultraviolet Light ◽  
Quantum Efficiency ◽  
Light Emitting Diodes ◽  
Internal Quantum Efficiency ◽  
Light Emitting ◽  
Highly Efficient ◽  
Near Ultraviolet ◽  
Ultraviolet Light Emitting Diodes

Approaches Towards the Ultimate Luminous Output Power of Light-Emitting Diodes: Bottlenecks and Remedies

2015 ◽  
Author(s):  
Xiaokun Zhang ◽  
Xiao-Dong Xiang ◽  
Yong Xiang
Keyword(s):  
Output Power ◽  
Light Emitting Diodes ◽  
Thermal Runaway ◽  
Efficiency Droop ◽  
Injection Current ◽  
Light Emitting ◽  
Excessive Heat ◽  
High Injection ◽  
Current Densities ◽  
The Cost

Although light-emitting diodes (LEDs) hold great promises for high-efficiency lighting applications, the cost per lumen still poses a challenge for LEDs to fast penetrate into the markets. Increasing the output power per LED chip reduces the number of chips required for a specific luminous flux, thus reducing the cost of LED luminaires. However, it is well known that the luminous output power of LEDs (Pout) cannot be enhanced simply by increasing the injection current density (Jinj) due to efficiency droop. Extensive efforts have been made towards avoiding efficiency droop at high injection current densities (e.g., Jinj > 50 A/cm2). Gardner et al. reported a double-heterostructure LED with an external quantum efficiency (EQE) of 40% at 200 A/cm2. Xie et al. introduced an electron-blocking layer into the LED devices and the EQE peak occurred at 900 A/cm2 approximately. Nevertheless, the EQE is always lower than 100%, excessive heat will accumulate in LEDs at high current densities and increase the junction temperatures, which will damage the device and limit its luminous output power and lifetime. In this paper, the recombination mechanism in the LED active area is analyzed and an analytic relationship between Pout and Jinj is proposed. The calculated results show that the best Pout currently achieved is far lower than its potential value. The temperature dependence of the Pout-Jinj relationship is also calculated and the thermal state of LEDs at high injection current densities predicted. The results demonstrate that LED luminaires with thermal management based on conventional fin-shaped heat sinks suffer from thermal runaway due to excessive heat accumulation before reaching their ultimate output power. The gap between the existing and predicted Pout is mainly due to thermal runaway of LED devices at high injection current densities, instead of efficiency droop. Therefore, the short-term solution of LED luminous output power enhancement should be better cooling of LED modules, such as jet/spray cooling, heat pipe cooling, or 3D embedded two-phase cooling. Long-term solutions continue to focus on reducing the efficiency droop with improved LED device structures and advanced materials.

Estimating internal quantum efficiency of light-emitting diodes from current–voltage curves

2019 ◽  
Vol 12 (3) ◽  
pp. 032002 ◽  
Author(s):  
Chenziyi Mi ◽  
Lai Wang ◽  
Jie Jin ◽  
Zhibiao Hao ◽  
Yi Luo ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
Light Emitting Diodes ◽  
Internal Quantum Efficiency ◽  
Light Emitting ◽  
Current Voltage
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