Regulation of the growth and photosynthesis of cherry tomato seedlings by different light irradiations of light emitting diodes (LED)

2012 ◽  
Vol 11 (22) ◽  
Author(s):  
Liu Xiaoying
Keyword(s):  
Light Emitting Diodes ◽  
Cherry Tomato ◽  
Light Emitting ◽  
Tomato Seedlings

scholarly journals The Efficiency of LED Irradiation for Cultivating High-Quality Tomato Seedlings

2021 ◽  
Vol 13 (16) ◽  
pp. 9426
Author(s):  
Kulyash Meiramkulova ◽  
Zhanar Tanybayeva ◽  
Assel Kydyrbekova ◽  
Arysgul Turbekova ◽  
Serik Aytkhozhin ◽  
...  
Keyword(s):  
High Pressure ◽  
Photosynthetic Pigments ◽  
Light Emitting Diodes ◽  
Red Light ◽  
Control Treatment ◽  
Photon Flux ◽  
Nanoparticle Coating ◽  
Light Emitting ◽  
Tomato Seedlings ◽  
Significant Difference

Light qualities are considered to affect many plant physiological processes during growth and development. To investigate how light qualities make an influence on tomato seedlings under greenhouse conditions, the growth and morphological parameters of tomato seedlings (Fortizia F1RC hybrid) were studied under three supplemental light irradiations such as light-emitting diodes with nanoparticle coating (LED 1—Red light-emitting diodes); Blue, Green, Yellow, Red light-emitting diodes (LED 2), and traditional high-pressure sodium (HPS) lamps with different photosynthetic photon flux density and the same irradiation time for 33 days. Morphological appearances of three groups of tomato seedlings were different between light treatments, that is, the plants under LED-1 and LED-2 were shorter than those under HPS, while stem diameter, leaf area, dry and fresh weights, and health indices of tomato seedlings grown under alternative light sources were higher than of those cultivated under traditional HPS lights. However, the higher plant height was in plants containing traditional high-pressure sodium lamps treatment. Photosynthetic pigments were shown to have a significant difference under respective light irradiations of LEDs. The levels of photosynthetic pigments were higher in the leaves of seedlings under LED 1 and LED 2, and lower in those that underwent HPS control treatment. Based on the data of morphological and statistical analysis, LEDs with nanoparticle coating proved to be beneficial factors for the growth of tomato seedlings under greenhouse conditions.

Injecting Inter-Layers and the Built-in Potential of Blue Polymer Light-Emitting Diodes

2000 ◽  
Vol 660 ◽  
Author(s):  
Thomas M. Brown ◽  
Ian S. Millard ◽  
David J. Lacey ◽  
Jeremy H. Burroughes ◽  
Richard H. Friend ◽  
...  
Keyword(s):  
Indium Tin Oxide ◽  
Light Emitting Diodes ◽  
Basic Structure ◽  
Thin Layers ◽  
Carrier Injection ◽  
Semiconducting Polymer ◽  
Light Emitting ◽  
Physical Mechanisms ◽  
Organic Solid ◽  
Polymer Light Emitting Diodes

ABSTRACTThe semiconducting-polymer/injecting-electrode heterojunction plays a crucial part in the operation of organic solid state devices. In polymer light-emitting diodes (LEDs), a common fundamental structure employed is Indium-Tin-Oxide/Polymer/Al. However, in order to fabricate efficient devices, alterations to this basic structure have to be carried out. The insertion of thin layers, between the electrodes and the emitting polymer, has been shown to greatly enhance LED performance, although the physical mechanisms underlying this effect remain unclear. Here, we use electro-absorption measurements of the built-in potential to monitor shifts in the barrier height at the electrode/polymer interface. We demonstrate that the main advantage brought about by inter-layers, such as poly(ethylenedioxythiophene)/poly(styrene sulphonic acid) (PEDOT:PSS) at the anode and Ca, LiF and CsF at the cathode, is a marked reduction of the barrier to carrier injection. The electro- absorption results also correlate with the electroluminescent characteristics of the LEDs.

Low-Temperature Operation of Green, Blue and UV InGaN/GaN Multiple-Quantum-Well Light-Emitting Diodes

2003 ◽  
Vol 764 ◽  
Author(s):  
X. A. Cao ◽  
S. F. LeBoeuf ◽  
J. L. Garrett ◽  
A. Ebong ◽  
L. B. Rowland ◽  
...  
Keyword(s):  
Quantum Well ◽  
Light Emitting Diodes ◽  
Multiple Quantum Well ◽  
Light Output ◽  
Localized States ◽  
Multiple Quantum ◽  
Nonradiative Recombination ◽  
Light Emitting ◽  
Temperature Range ◽  
Green Leds

Absract:Temperature-dependent electroluminescence (EL) of InGaN/GaN multiple-quantum-well light-emitting diodes (LEDs) with peak emission energies ranging from 2.3 eV (green) to 3.3 eV (UV) has been studied over a wide temperature range (5-300 K). As the temperature is decreased from 300 K to 150 K, the EL intensity increases in all devices due to reduced nonradiative recombination and improved carrier confinement. However, LED operation at lower temperatures (150-5 K) is a strong function of In ratio in the active layer. For the green LEDs, emission intensity increases monotonically in the whole temperature range, while for the blue and UV LEDs, a remarkable decrease of the light output was observed, accompanied by a large redshift of the peak energy. The discrepancy can be attributed to various amounts of localization states caused by In composition fluctuation in the QW active regions. Based on a rate equation analysis, we find that the densities of the localized states in the green LEDs are more than two orders of magnitude higher than that in the UV LED. The large number of localized states in the green LEDs are crucial to maintain high-efficiency carrier capture at low temperatures.

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