scholarly journals Enhanced Optical Output of Near-Ultraviolet Light-Emitting Diodes by a Monolayer of Nanospheres

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Wei Wan ◽  
Zhanxu Chen ◽  
Yongzhu Chen ◽  
Gengyan Chen
Keyword(s):  
Indium Tin Oxide ◽  
Light Emitting Diodes ◽  
Low Cost ◽  
Incident Light ◽  
Light Extraction Efficiency ◽  
Light Emitting ◽  
Hexagonal Close Packed ◽  
Exit Surface ◽  
Near Ultraviolet ◽  
Optical Output

The optical output of near-ultraviolet (NUV) light-emitting diodes (LEDs) was improved by including a monolayer of hexagonal close-packed polystyrene (PS) nanospheres. PS nanospheres with different sizes were deposited on the indium tin oxide layer of the NUV LEDs. The electroluminescence results showed that the light extraction efficiency of the NUV LEDs was increased by the inclusion of PS nanospheres, and the maximum optical output enhancement was obtained when the size of the nanospheres was close to the light wavelength. The largest enhancement of the optical output of 1.27-fold was obtained at an injection current of 100 mA. The enhanced optical output was attributed to part of the incident light beyond the critical angle being extracted when the exit surface of the NUV LEDs had a PS nanosphere monolayer. This method may serve as a low-cost and effective approach to raise the efficiency of NUV LEDs.

scholarly journals Nanostructural Effect of ZnO on Light Extraction Efficiency of Near-Ultraviolet Light-Emitting Diodes

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Young Jae Park ◽  
Hyounsuk Song ◽  
Kang Bok Ko ◽  
Beo Deul Ryu ◽  
Tran Viet Cuong ◽  
...  
Keyword(s):  
Ultraviolet Light ◽  
Indium Tin Oxide ◽  
Light Emitting Diodes ◽  
Light Output ◽  
Light Extraction Efficiency ◽  
Zno Nanostructures ◽  
Light Emitting ◽  
Near Ultraviolet ◽  
Output Efficiency ◽  
Ultraviolet Light Emitting Diodes

The effect of ZnO nanostructures on the light output power of 375 nm near-ultraviolet light-emitting diodes (NUV-LEDs) was investigated by comparing one-dimensional (1D) nanorods (NR-ZnO) with two-dimensional (2D) nanosheets (NS-ZnO). ZnO nanostructures were grown on a planar indium tin oxide (ITO) by solution based method at low temperature of 90°C without degradation of the forward voltage. At an injection current of 100 mA, the light output efficiency of NUV-LED with NR-ZnO was enhanced by around 30% compared to the conventional NUV-LEDs without ZnO nanostructures. This improvement is due to the formation of a surface texturing, resulting in a larger escape cone and a multiple scattering for the photons in the NUV-LED, whereas the light output efficiency of NUV-LED with NS-ZnO was lower than that of the conventional NUV-LEDs due to the internal reflection and light absorption in the defective sites of NS-ZnO.

scholarly journals Light Output Enhancement of InGaN/GaN Light-Emitting Diodes with Contrasting Indium Tin-Oxide Nanopatterned Structures

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Sang Hyun Jung ◽  
Keun Man Song ◽  
Young Su Choi ◽  
Hyeong-Ho Park ◽  
Hyun-Beom Shin ◽  
...  
Keyword(s):  
Circular Hole ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Inductively Coupled Plasma ◽  
Light Emitting Diodes ◽  
Hexagonal Lattice ◽  
Light Output ◽  
Light Extraction Efficiency ◽  
Output Intensity ◽  
Light Emitting

Various nanopatterns on the transparent conducting indium tin oxide (ITO) layer are investigated to enhance the light extraction efficiency of the InGaN/GaN light-emitting diodes (LEDs). Triangular, square, and circular nanohole patterns with the square and hexagonal lattices are fabricated on the ITO layer by an electron beam lithography and inductively coupled plasma dry etching processes. The circular hole pattern with a hexagonal geometry is found to be the most effective among the studied structures. Light output intensity measurements reveal that the circular hole nanopatterned ITO LEDs with a hexagonal lattice show up to 35.6% enhancement of output intensity compared to the sample without nanopatterns.

scholarly journals Improvement of Light Extraction in Deep Ultraviolet GaN Light Emitting Diodes with Mesh P-Contacts

2020 ◽  
Vol 10 (17) ◽  
pp. 5783
Author(s):  
Shiou-Yi Kuo ◽  
Chia-Jui Chang ◽  
Zhen-Ting Huang ◽  
Tien-Chang Lu
Keyword(s):  
Indium Tin Oxide ◽  
Light Emitting Diodes ◽  
Ultra Violet ◽  
Light Extraction ◽  
Light Extraction Efficiency ◽  
Light Emitting ◽  
Duv Led ◽  
Lower Light ◽  
Deep Ultraviolet ◽  
P Type

One of the main reasons that the emission efficiency of GaN-based light-emitting diodes (LEDs) decreases significantly as the emission wavelength shorter than 300 nm is the low light extraction efficiency (LEE). Especially in deep ultra-violet (DUV) LEDs, light propagating outside the escape cone and being reflected back to the semiconductor or substrate layer is absorbed not only by active layers but also by p-type layers with narrower bandgaps and electrodes that are neither transparent nor reflective of the DUV wavelength. In this report, we propose a DUV LED structure with mesh p-GaN/indium-tin-oxide (ITO) contacts and a Ti/Al/Ni/Au layer as a reflective layer to improve LEE. The mesh p-GaN/ITO DUV LED showed an output power of 12% higher than that from the conventional DUV LED due to the lower light absorption at 280 nm.

Improvement of near-ultraviolet nitride-based light emitting diodes with mesh indium tin oxide contact layers

2006 ◽  
Vol 89 (20) ◽  
pp. 201104 ◽  
Author(s):  
C. H. Kuo ◽  
C. M. Chen ◽  
C. W. Kuo ◽  
C. J. Tun ◽  
C. J. Pan ◽  
...  
Keyword(s):  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
Near Ultraviolet

Characterization of Polymer Light Emitting Diodes Fabricated by Ionically Self-Assembled Monolayer Technique

1999 ◽  
Vol 598 ◽  
Author(s):  
D. Marciu ◽  
M. B. Miller ◽  
J. R. Heflin ◽  
M. A. Murray ◽  
A. L. Ritter ◽  
...  
Keyword(s):  
Film Thickness ◽  
Indium Tin Oxide ◽  
Light Emitting Diodes ◽  
Low Cost ◽  
Electrolyte Solutions ◽  
Aluminum Electrode ◽  
Large Area ◽  
Self Assembled Monolayer ◽  
Light Emitting ◽  
Self Assembled

ABSTRACTIonically self-assembled monolayer (ISAM) films are a recently developed class of materials that allows detailed structural and thickness control at the sub-nanometer level combined with ease of manufacturing and low cost. The ISAM fabrication method simply involves the dipping of a charged substrate alternately into polycationic and polyanionic aqueous solutions at room temperatures. Importantly, the ISAM technique yields exceptionally homogeneous, large area films with excellent control of total film thickness. We describe detailed studies of ISAM light emitting diodes incorporating poly(para-phenylene vinylene) (PPV) as the light emitting polymer. The individual thickness of each monolayer and the interpenetration of adjacent layers can be precisely controlled through the parameters of the electrolyte solutions. The effects of the pH and ionic strength of the immersion solutions, the total film thickness, and the PPV thermal conversion parameters on the photoluminescence and electroluminescence yields have been systematically studied. The ISAM process also allows the advantage of depositing well-defined thicknesses of separate polymers at the indium tin oxide and the aluminum electrode interfaces.

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