Ultimate limit and temperature dependency of light-emitting diode efficiency

2009 ◽  
Vol 105 (9) ◽  
pp. 093119 ◽  
Author(s):  
Oskari Heikkilä ◽  
Jani Oksanen ◽  
Jukka Tulkki
Keyword(s):  
Light Emitting Diode ◽  
Temperature Dependency ◽  
Light Emitting ◽  
Ultimate Limit

scholarly journals Effects of Temperature and Host Concentration on the Supramolecular Enantiodifferentiating [4 + 4] Photodimerization of 2-Anthracenecarboxylate through Triplet-Triplet Annihilation Catalyzed by Pt-Modified Cyclodextrins

Molecules ◽  
2019 ◽  
Vol 24 (8) ◽  
pp. 1502 ◽  
Author(s):  
Ming Rao ◽  
Wanhua Wu ◽  
Cheng Yang
Keyword(s):  
Light Emitting Diode ◽  
Temperature Dependency ◽  
Light Emitting ◽  
Modified Cyclodextrins ◽  
Direct Irradiation ◽  
Visible Light Driven ◽  
Significant Temperature ◽  
Effects Of Temperature ◽  
532 Nm ◽  
Triplet Triplet Annihilation

Visible-light-driven photocatalytic supramolecular enantiodifferentiating dimerization of 2-anthracenecarboxylic acid (AC) through triplet-triplet annihilation (TTA), mediated by the Schiff base Pt(II) complex (Pt-1, Pt-2, and Pt-3) was studied. The host concentration and the temperature effects on the stereoselectivity were comprehensively investigated. Increasing the concentration of sensitizers/hosts significantly enhanced the conversion of the photoreaction but led to reduced enantioselectivities of the chiral photodimers 2 and 3 when the photoreaction was triggered by a 532 nm laser, which was in contrast with the results obtained by direct irradiation of AC with a 365 nm light-emitting diode (LED) lamp, due to the aggregation of the sensitizer/host in water. The cyclization of AC through triplet-triplet annihilation displayed significant temperature dependency when Pt-3 was employed as the sensitizer/host. Increasing the temperature from 0 °C to 30 °C with 5% equiv. of Pt-3 led to a great increase of the ee of 2 from 2.1% to 31.6%. However, hardly any temperature dependency was observed when the photodimerization was mediated by other sensitizers and/or hosts, or the photoreaction was triggered directly with a 365 nm LED lamp.

Synchronization of Chaotic Quantum Dot Light Emitting Diodes under Optical Feedback Effect

2020 ◽  
pp. 144-148
Keyword(s):  
Quantum Dot ◽  
Delay Time ◽  
Chaos Synchronization ◽  
Optical Feedback ◽  
Light Emitting Diode ◽  
Feedback Effect ◽  
Complete Synchronization ◽  
Light Emitting ◽  
Coupling Methods ◽  
Coupling Parameters

Chaos synchronization of delayed quantum dot light emitting diode has been studied theortetically which are coupled via the unidirectional and bidirectional. at synchronization of chaotic, The dynamics is identical with delayed optical feedback for those coupling methods. Depending on the coupling parameters and delay time the system exhibits complete synchronization, . Under proper conditions, the receiver quantum dot light emitting diode can be satisfactorily synchronized with the transmitter quantum dot light emitting diode due to the optical feedback effect.

Effects of Nitridation Time on Top-emission Inverted Organic Light Emitting Diode

PIERS Online ◽  
2007 ◽  
Vol 3 (6) ◽  
pp. 821-824 ◽  
Author(s):  
Chien-Chang Tseng ◽  
Liang-Wen Ji ◽  
Yu Sheng Tsai ◽  
Fuh-Shyang Juang
Keyword(s):  
Light Emitting Diode ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Nitridation Time ◽  
Organic Light

Items Searching in Factory Warehouse Using Arduino Module

2019 ◽  
Vol 1 (1) ◽  
pp. 1-14
Author(s):  
Tan Liong Ching ◽  
Nureize Binti Arbaiy
Keyword(s):  
Inventory Management ◽  
Liquid Crystal Display ◽  
Light Emitting Diode ◽  
Storage System ◽  
Voice Recognition ◽  
Inventory System ◽  
Search Process ◽  
Light Emitting ◽  
Recognition Function ◽  
Light Function

The smart store system (F3 Storage System) provides an inventory system function, and is supported by voice recognition for items searching purpose in the warehouse. This system is aimed to improve effectiveness in item searching process for the warehouse management. An inventory system structures is employed in this system to enable items management. Voice recognition facility helps the worker to search item in an effective way. Worker can use voice recognition function to search the item in the warehouse, and searched information of the item will be displayed in the liquid crystal display (LCD) screen. Meanwhile, the location of the item will be physically indicated by the light emitting diode (LED) light function. The developed system also contains a barcode system to enhance the process of scheduling warehouse activity. Such facilities will enhance the capabilities of existing inventory management systems in warehouses. Prototyping model is used to assist project development. Arduino technology is used to enable integrated hardware and software to read data or input. With Arduino technology, traditional search items by using text and search functionality are enhanced to allow speech functionality. This functionality makes the search process faster and more efficient.

Temperature and Humidity Dependent Reliability Analysis of RGB LED Chips

2006 ◽  
Author(s):  
Jun-Xian Fu ◽  
Shukri Souri ◽  
James S. Harris
Keyword(s):  
Reliability Analysis ◽  
Printed Circuit Board ◽  
Light Emitting Diode ◽  
Circuit Board ◽  
Light Emitting ◽  
Printed Circuit ◽  
Root Cause ◽  
Micro Cracks ◽  
Temperature And Humidity

Abstract Temperature and humidity dependent reliability analysis was performed based on a case study involving an indicator printed-circuit board with surface-mounted multiple-die red, green and blue light-emitting diode chips. Reported intermittent failures were investigated and the root cause was attributed to a non-optimized reflow process that resulted in micro-cracks and delaminations within the molding resin of the chips.

Characterization and Elimination of Forward Snapback Defects in GaAs Light Emitting Diodes

1996 ◽  
Author(s):  
J. Zimmer ◽  
D. Nielsen ◽  
T.A. Anderson ◽  
M. Schade ◽  
N. Saha ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Light Emitting Diode ◽  
Elevated Concentration ◽  
Forward Voltage ◽  
Light Emitting ◽  
Intermittent Yield ◽  
Si Doped ◽  
Secondary Ion ◽  
Furnace Pressure

Abstract The p-n junction of a GaAs light emitting diode is fabricated using liquid phase epitaxy (LPE). The junction is grown on a Si doped (~1018/cm3) GaAs substrate. Intermittent yield loss due to forward voltage snapback was observed. Historically, out of specification forward voltage (Vf) parameters have been correlated to abnormalities in the junction formation. Scanning electron (SEM) and optical microscopy of cleaved and stained samples revealed a continuous layer of material approximately 2.5 to 3.0 urn thick at the n-epi/substrate interface. Characterization of a defective wafer via secondary ion mass spectroscopy (SIMS) revealed an elevated concentration of O throughout the region containing the defect. X-ray Photoelectron Spectroscopy (XPS) and Auger Electron Spectroscopy (AES) data taken from a wafer prior to growth of the epi layers did not reveal any unusual oxidation or contamination. Extensive review of the processing data suggested LPE furnace pressure was the obvious source of variability. Processing wafers through the LPE furnace with a slight positive H2 gas pressure has greatly reduced the occurrence of this defect.

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