Blue Electroluminescent Devices Fabricated from Silicon and Germanium Nanocrystals

1997 ◽  
Vol 471 ◽  
Author(s):  
Gildardo R. Delgado ◽  
Howard W. H. Lee ◽  
Khashayar Pakbaz
Keyword(s):  
Flat Panel Display ◽  
Electron Hole ◽  
Small Organic Molecules ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Si Nanocrystals ◽  
Germanium Nanocrystals ◽  
Silicon And Germanium ◽  
The Cost ◽  
Hole Recombination

ABSTRACTBlue electroluminescent (EL) devices were fabricated with Si nanocrystals produced by ultrasonic fracturing of porous silicon (PSi) as well as silicon and germanium nanocrystals synthesized through a control chemical reaction. The active EL material consists of Si and Ge nanocrystals embedded in various host matrices such as polyvinylcarbazole (PVK), polymethylmethacrylate (PMMA), silica sol-gels and other organic polymers and small organic molecules. Several device configurations were used to induce EL processes that rely on radiative electron-hole recombination within the nanocrystals. We report on the optical and electrical properties of these devices. Applications for these EL devices include highly efficient light emitting devices. The cost and ease of processing of these material systems make them potentially ideal for flat panel display applications.

New method to control defect reaction induced by electron-hole recombination for long-living widegap light-emitting devices

2008 ◽  
Vol 19 (S1) ◽  
pp. 299-302
Author(s):  
Masahiro Adachi ◽  
Yutaka Hashimoto ◽  
Katsuhisa Kanzaki ◽  
Shuji Ohashi ◽  
Yasuhiro Morita ◽  
...  
Keyword(s):  
New Method ◽  
Electron Hole ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Defect Reaction ◽  
Hole Recombination

scholarly journals The dark exciton ground state promotes photon-pair emission in individual perovskite nanocrystals

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Philippe Tamarat ◽  
Lei Hou ◽  
Jean-Baptiste Trebbia ◽  
Abhishek Swarnkar ◽  
Louis Biadala ◽  
...  
Keyword(s):  
Near Infrared ◽  
Exciton State ◽  
Lead Iodide ◽  
Electron Hole ◽  
Light Emitting ◽  
Perovskite Nanocrystals ◽  
Light Emitting Devices ◽  
Optical And Electronic Properties ◽  
Wide Range ◽  
Halide Perovskites

AbstractCesium lead halide perovskites exhibit outstanding optical and electronic properties for a wide range of applications in optoelectronics and for light-emitting devices. Yet, the physics of the band-edge exciton, whose recombination is at the origin of the photoluminescence, is not elucidated. Here, we unveil the exciton fine structure of individual cesium lead iodide perovskite nanocrystals and demonstrate that it is governed by the electron-hole exchange interaction and nanocrystal shape anisotropy. The lowest-energy exciton state is a long-lived dark singlet state, which promotes the creation of biexcitons at low temperatures and thus correlated photon pairs. These bright quantum emitters in the near-infrared have a photon statistics that can readily be tuned from bunching to antibunching, using magnetic or thermal coupling between dark and bright exciton sublevels.

Influence of potential barrier materials on device performance

2002 ◽  
Vol 725 ◽  
Author(s):  
Z. Y. Xie ◽  
Y. Q. Li ◽  
T. C. Wong ◽  
F. L. Wong ◽  
M. K. Fung ◽  
...  
Keyword(s):  
Electron Mobility ◽  
Power Efficiency ◽  
Device Performance ◽  
High Electron ◽  
Electron Hole ◽  
Light Emitting ◽  
Barrier Materials ◽  
Mobility Device ◽  
Luminance Efficiency ◽  
Hole Recombination

AbstractAn organic light-emitting device (OLED) having a double-heterostructure of ITO/NPB/DCMdoped Alq3/BCP/Alq3/MgAg was constructed to form a narrow recombination zone where both charge carriers and excitons are confined, thus resulting in efficient electron-hole recombination and energy transfer. It was found that though luminance efficiency was enhanced, the low electron mobility of BCP resulted in higher driving voltages and limited the improvement of power efficiency. Significant improvements on both quantum efficiency and power efficiency were achieved by replace 1,3,5-tri(phenyl-2-benzimidazoly)-benzene (TPBI) for BCP, and were correlated with its high electron mobility. Device performance was further improved in the structure ITO/NPB/DCM-doped Alq3/TPBI/LiF/MgAg with a maximum luminance efficiency 6.03cd/A and a power efficiency of 5.94 lm/W.

New Light Emitting Polymers and High Energy Hosts for Triplet Emission

2004 ◽  
Vol 846 ◽  
Author(s):  
Chris S. K. Mak ◽  
Scott E. Watkins ◽  
Charlotte K. Williams ◽  
Nicholas R. Evans ◽  
Khai Leok Chan ◽  
...  
Keyword(s):  
Green Light ◽  
High Energy ◽  
Design Solution ◽  
Coupling Reactions ◽  
Triplet Energy ◽  
Electron Hole ◽  
Efficient Energy Transfer ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Cross Coupling Reactions

ABSTRACTThis paper describes two aspects of research aimed at harnessing the triplet energy generated in electron-hole recombination in polymer electroluminescent devices. The purpose is to design solution-processible phosphorescent organometallic triplet emitters and to design high triplet energy polymer hosts that can transfer triplet energy to the phosphorescent guests. The method employed Suzuki cross coupling reactions to incorporate either phosphorescent cores or high energy triplet monomers covalently into polymer hosts to evaluate their optoelectronic properties. The results showed (i) efficient energy transfer from polyfluorene hosts to red phosphorescent guests and (ii) that pyridine and carbazole monomers could raise triplet energies of hosts. It is concluded that these approaches offer promise in the design of solution processible electrophosphorescent materials for red and green light emitting devices.

The Possible Mechanism of Excitation of the f - f Emission from Er-O Clusters in Silicon

1996 ◽  
Vol 422 ◽  
Author(s):  
V. F. Masterov ◽  
L. G. Gerchikov
Keyword(s):  
Quantum Dot ◽  
Quantum Well ◽  
Forward Bias ◽  
Electron Trap ◽  
Electron Hole ◽  
Electron Level ◽  
Light Emitting ◽  
Trapped Electron ◽  
Hole Recombination

AbstractThe Er2O3 quantum dot (cluster) with dimensions about 1.2nm in silicon is discussed as the possible source of the Er related emission in Si:Er,O, excited by photogenerated carriers or in a light-emitting diodes (LED) at forward bias. This quantum dot is represented as a spherical quantum well 0.9eV in depth. The electron level with energy about 0.15eV below the bottom of the silicon conduction band plays role of an electron trap. The trapped electron interacts with a hole in valence band of silicon forming “indirect” exciton bonded to quantum well. The energy is transferred to f - shell of erbium by the Auger electron - hole recombination.

Quantum Dot Array LED Research with ZnO as an Electron Transport Layer

2013 ◽  
Vol 333-335 ◽  
pp. 1895-1898
Author(s):  
Jia Zhao ◽  
Xiao Yu Zhang ◽  
Yu Zhang ◽  
Yi Feng ◽  
Tie Qiang Zhang ◽  
...  
Keyword(s):  
Electron Transport ◽  
Quantum Dot ◽  
Transport Layer ◽  
Electron Transport Layer ◽  
Core Shell ◽  
Cdse Core ◽  
Electron Hole ◽  
Light Emitting ◽  
Light Stability ◽  
Hole Recombination

As a new light-emitting material, quantum dot having the advantages of other materials that can not be replaced. It is not only the fluorescence quantum yield, and light stability. Therefore, we use CdSe core-shell structure of the quantum dot LED devices as the electron-hole recombination layer. In this paper, we synthesized emission peak is located at 588nm CdSe core-shell quantum dots, and made array display LED devices with ZnO as the electron transport layer.

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