scholarly journals Influence of Surface Passivation on Perovskite CsPbBr1.2I1.8 Quantum Dots and Application of High Purity Red Light-Emitting Diodes

2021 ◽  
Author(s):  
Lung-Chien Chen ◽  
Yen-Hung Tien ◽  
Jianjun Tian
Keyword(s):  
Quantum Dots ◽  
Surface Passivation ◽  
Light Emitting Diode ◽  
Red Light ◽  
Lead Nitrate ◽  
Luminous Efficiency ◽  
Trioctylphosphine Oxide ◽  
Light Emitting ◽  
Co Doped

Abstract In this work, trioctylphosphine oxide (TOPO) ligand is employed to improve the quality of CsPbBr1.2I1.8 quantum dots (QDs) films. Lead nitrate (Pb(NO3)2) is also used to passivate the surface of the films. The study of ligand and surface passivation on the luminous efficiency of red light-emitting diode (LED) is discussed. The CsPbBr1.2I1.8 QDs films co-doped with TOPO and Pb(NO3)2 can effectively improve the performance of the CsPbBr1.2I1.8 QDs LEDs due to reduction of non-radiation recombination of the carriers and smooth morphology in the active layer, thus improving the injection and transportation capabilities of carriers. As a result, the highest luminosity and current efficiency are 502.7 cd/m2 and 0.175 cd/A, respectively.

scholarly journals Red Light-Emitting Diodes with All-Inorganic CsPbI3/TOPO Composite Nanowires Color Conversion Films

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Lung-Chien Chen ◽  
Yi-Tsung Chang ◽  
Ching-Ho Tien ◽  
Yu-Chun Yeh ◽  
Zong-Liang Tseng ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Light Emitting Diode ◽  
Red Light ◽  
Trioctylphosphine Oxide ◽  
Optical And Electrical Properties ◽  
Colloidal Solutions ◽  
High Quality ◽  
Light Emitting ◽  
Hot Injection ◽  
Color Conversion

AbstractThis work presents a method for obtaining a color-converted red light source through a combination of a blue GaN light-emitting diode and a red fluorescent color conversion film of a perovskite CsPbI3/TOPO composite. High-quality CsPbI3 quantum dots (QDs) were prepared using the hot-injection method. The colloidal QD solutions were mixed with different ratios of trioctylphosphine oxide (TOPO) to form nanowires. The color conversion films prepared by the mixed ultraviolet resin and colloidal solutions were coated on blue LEDs. The optical and electrical properties of the devices were measured and analyzed at an injection current of 50 mA; it was observed that the strongest red light intensity was 93.1 cd/m2 and the external quantum efficiency was 5.7% at a wavelength of approximately 708 nm when CsPbI3/TOPO was 1:0.35.

scholarly journals Ultrawide Color Gamut Perovskite and CdSe/ZnS Quantum-Dots-Based White Light-Emitting Diode with High Luminous Efficiency

Nanomaterials ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 1314 ◽  
Author(s):  
Chih-Hao Lin ◽  
Chieh-Yu Kang ◽  
Akta Verma ◽  
Tingzhu Wu ◽  
Yung-Min Pai ◽  
...  
Keyword(s):  
Quantum Dots ◽  
White Light ◽  
High Efficiency ◽  
Light Emitting Diode ◽  
Red Light ◽  
Color Gamut ◽  
Television System ◽  
Light Emitting ◽  
Term Operation ◽  
Liquid Type

We demonstrate excellent color quality of liquid-type white light-emitting diodes (WLEDs) using a combination of green light-emitting CsPbBr3 and red light-emitting CdSe/ZnS quantum dots (QDs). Previously, we reported red (CsPbBr1.2I1.8) and green (CsPbBr3) perovskite QDs (PQDs)-based WLEDs with high color gamut, which manifested fast anion exchange and stability issues. Herein, the replacement of red PQDs with CdSe/ZnS QDs has resolved the aforementioned problems effectively and improved both stability and efficiency. Further, the proposed liquid-type device possesses outstanding color gamut performance (132% of National Television System Committee and 99% of Rec. 2020). It also shows a high efficiency of 66 lm/W and an excellent long-term operation stability for over 1000 h.

scholarly journals Red Light-Emitting Diode Based on Blue InGaN Chip with CdTe x S(1 − x) Quantum Dots

2017 ◽  
Vol 12 (1) ◽  
Author(s):  
Rongfang Wang ◽  
Xingming Wei ◽  
Liqin Qin ◽  
Zhihui Luo ◽  
Chunjie Liang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Light Emitting Diode ◽  
Red Light ◽  
Light Emitting

scholarly journals COLORIMETRIC MEASUREMENTS OF COCOA BEANS (Theobroma cacao)

2013 ◽  
Vol 3 (2) ◽  
pp. 52
Author(s):  
Charles C.E. Meulemans ◽  
Untung Surapati T. ◽  
Ardin Tjatjo
Keyword(s):  
Diffuse Reflection ◽  
Electronic Device ◽  
Light Emitting Diode ◽  
Red Light ◽  
Cocoa Beans ◽  
Silicon Photodiode ◽  
Light Emitting ◽  
Reflected Light ◽  
Colorimetric Measurements

A series of studies have been carried out to develop a simple, easy to use, and affordable device to measure the colour of cocoa beans. The present paper reports the development of the device based on colorimetric principles. An electronic device which enables cocoa smallholders to give an objective “onefigure” indication of the quality of their cocoa beans was described. A sensor was constructed which contained a red light emitting diode (LED) illuminating the target and a silicon photodiode detecting the reflected light. Because of the considerable difference in colour between dried unfermented and fermented cocoa beans, the differences in diffuse reflection of red light (660 nm) could be about 20 and very easy to measure. The method was checked with a spectrophotometer in the fixed mode at 660 nm, which revealed a high correlation coefficient. The sensor was combined with a microprocessor controlled electronic device for fast measurement of cocoa beans without any calculations which automatically counts the number of measured beans and gives the resulting average reflection value.

scholarly journals Study on the Color-Compensation Effect of Composite Orange-Red Quantum Dots in WLED Application

2020 ◽  
Author(s):  
Xiaoyue Hu ◽  
Yangyang Xie ◽  
Chong Geng ◽  
Shu Xu ◽  
Wengang Bi
Keyword(s):  
Quantum Dots ◽  
Light Emitting Diode ◽  
Red Light ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Light Emitting ◽  
Light Region ◽  
Color Compensation ◽  
Donor Acceptor ◽  
Color Rendering

Abstract Quantum dots (QDs) as emerging light-converting materials show the advantage of enhancing color quality of white light-emitting diode (WLED). However, WLEDs employing narrow-emitting monochromic QDs usually present unsatisfactory color rendering in the orange region. Herein, composite orange-red QDs (composite-QDs) are developed through mixing CdSe/ZnS based orange QDs (O-QDs) and red QDs (R-QDs) to compensate the orange-red light for WLEDs. We investigated the effect of self-absorption and fluorescence resonance energy transfer (FRET) process in composite-QDs on the spectral controllability and fluorescent quenching in WLEDs. The concentration and donor/acceptor ratios were also taken into account to analyze the FRET efficiency and help identify suitable composite-QDs for color compensation in the orange-red light region. As the result, the optimized composite-QDs effectively improve the color rendering index of the WLED compared with monochromatic QDs.

scholarly journals High Stability of Liquid-Typed White Light-Emitting Diode with Zn0.8Cd0.2S White Quantum Dots

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 415
Author(s):  
Chin-Chuan Huang ◽  
Kuo-Hsiung Chu ◽  
Chin-Wei Sher ◽  
Chun-Liang Lin ◽  
Yan-Kuin Su ◽  
...  
Keyword(s):  
Quantum Dots ◽  
White Light ◽  
High Stability ◽  
High Efficiency ◽  
Light Emitting Diode ◽  
Luminous Efficiency ◽  
Color Temperature ◽  
Chemical Route ◽  
Light Emitting ◽  
The Stability

In this study, we demonstrate a new design of white light-emitting diode (WLED) with high stability and luminous efficiency as well as positive aging. Colloidal ternary Zn0.8Cd0.2S (named Zn0.8) white quantum dots (WQDs) were prepared by chemical route and dispersed in xylene, integrating them into an ultraviolet light-emitting diode (UV-LED) to form WQD-white light emitting diode (WQD-WLED). High efficiency, high color quality and excellent reliability of WQD-WLED with neutral white correlated color temperature (CCT) can be obtained. The experimental results indicate that the stability of relative luminous efficiency and color rendering index (CRI) of the WQD-WLED can reach up to 160 and 82%, respectively. Moreover, the WQD-WLED can operate more than 1000 h under 100 mA, and the quantity of WQDs in the glass package can be reduced.

scholarly journals White Light Electroluminescence by Organic-Inorganic Heterostructures with CdSe Quantum Dots as Red Light Emitters

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Ilker Oner ◽  
Elias Stathatos ◽  
Canan Varlikli
Keyword(s):  
Quantum Dots ◽  
Light Emission ◽  
Red Light ◽  
Conductive Polymer ◽  
Host Material ◽  
Trioctylphosphine Oxide ◽  
Cdse Quantum Dots ◽  
Light Emitters ◽  
Emission Layer ◽  
Light Emitting

We have developed a white organic light-emitting diode featuring a double emission layer comprising a blue light-emitting conductive polymer as a host material for Cadmium Selenide (CdSe) quantum dots as red light emitters and tris-(8-hydroxyquinoline) aluminium thin layer for green light emission. The Commission Internationale de l'Eclairage coordinates of the emitting light of the device were found to be (0.32, 0.40) which were only slightly changed over a range of applied voltages between 5 and 10 volts. The use of CdSe nanocrystalline quantum dots (surface-stabilized with hexadecylamine/trioctylphosphine oxide ligands) in the hybrid heterostructure with poly(9,9-di-n-octylfluorenyl-2,7-diyl) conductive polymer was studied for a variety of CdSe concentrations developing the performance of the device in means of overcoming segregation problems in the blend. Besides, constituents' ratio was further examined for the exploration of possible energy transfer from polymer host material to the CdSe quantum dots as a key factor for well-balanced emission in the electroluminescent devices.

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