Tunnel-regenerated multiple-active-region light-emitting diodes with high efficiency

2001 ◽  
Vol 79 (18) ◽  
pp. 2985-2986 ◽  
Author(s):  
Xia Guo ◽  
Guang-Di Shen ◽  
Guo-Hong Wang ◽  
Wen-Jun Zhu ◽  
Jin-Yu Du ◽  
...  
Keyword(s):  
Active Region ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Light Emitting

High efficiency tunneling-regenerated multi-active region light-emitting diodes

2000 ◽  
Author(s):  
Xia Guo ◽  
Guangdi Shen ◽  
Guohong Wang ◽  
Jinyu Du ◽  
WeiLing Guo ◽  
...  
Keyword(s):  
Active Region ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Light Emitting

scholarly journals Effect of Inhomogeneous Broadening in Ultraviolet III-Nitride Light-Emitting Diodes

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7890
Author(s):  
Friedhard Römer ◽  
Martin Guttmann ◽  
Tim Wernicke ◽  
Michael Kneissl ◽  
Bernd Witzigmann
Keyword(s):  
Active Region ◽  
Quantum Wells ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Inhomogeneous Broadening ◽  
Aluminium Content ◽  
Hole Density ◽  
Free Hole ◽  
Light Emitting ◽  
The Impact

In the past years, light-emitting diodes (LED) made of GaN and its related ternary compounds with indium and aluminium have become an enabling technology in all areas of lighting. Visible LEDs have yet matured, but research on deep ultraviolet (UV) LEDs is still in progress. The polarisation in the anisotropic wurtzite lattice and the low free hole density in p-doped III-nitride compounds with high aluminium content make the design for high efficiency a critical step. The growth kinetics of the rather thin active quantum wells in III-nitride LEDs makes them prone to inhomogeneous broadening (IHB). Physical modelling of the active region of III-nitride LEDs supports the optimisation by revealing the opaque active region physics. In this work, we analyse the impact of the IHB on the luminescence and carrier transport III-nitride LEDs with multi-quantum well (MQW) active regions by numerical simulations comparing them to experimental results. The IHB is modelled with a statistical model that enables efficient and deterministic simulations. We analyse how the lumped electronic characteristics including the quantum efficiency and the diode ideality factor are related to the IHB and discuss how they can be used in the optimisation process.

scholarly journals Effects of a Reduced Effective Active Region Volume on Wavelength-Dependent Efficiency Droop of InGaN-Based Light-Emitting Diodes

2018 ◽  
Vol 8 (11) ◽  
pp. 2138 ◽  
Author(s):  
Panpan Li ◽  
Yongbing Zhao ◽  
Xiaoyan Yi ◽  
Hongjian Li
Keyword(s):  
Active Region ◽  
Quantum Well ◽  
Current Density ◽  
Carrier Density ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Efficiency Droop ◽  
Effective Volume ◽  
Light Emitting ◽  
Near Ultraviolet

In this study, wavelength-dependent efficiency droop phenomena in InGaN-based light-emitting diodes (LEDs) by a reduced effective active region volume were investigated. Different effective active region volumes can be extracted from theoretical fitting to the efficiency-versus-current curves of standard high efficiency InGaN near-ultraviolet, blue, and green LEDs. It has been found that the effective volume of the active region reduces more significantly with increasing emission wavelength, resulting in a lower onset-droop current density, as well as a more severe droop. Increasing the quantum well (QW) thickness to reduce carrier density is proposed as an effective way to alleviate the efficiency droop.

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.

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.

Ultra-High Efficiency White Light Emitting Diodes

2006 ◽  
Vol 45 (No. 41) ◽  
pp. L1084-L1086 ◽  
Author(s):  
Yukio Narukawa ◽  
Junya Narita ◽  
Takahiko Sakamoto ◽  
Kouichiro Deguchi ◽  
Takao Yamada ◽  
...  
Keyword(s):  
White Light ◽  
High Efficiency ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
White Light Emitting Diodes
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