Light-emitting devices electroluminescence

Major Applications Organic light emitting devices, electroluminescent devices, laser dyes, photography, plastic scintillation applications, 3 herbicides, eyeglass lenses, cosmetics Safety/Toxicity Endocrine disrupters " ... 

The enormous progress in the field of electroluminescent conjugated polymers has led to performances of oiganic light-emitting devices (LEDs) that are comparable and in some aspects superior to their inorganic counterparts 11). Quantum efficiencies in excess of 5% have been demonstrated [2] and show that a high fraction of the injected carriers in a polymeric electroluminescence (EL) device form electronic excitations which recombine radiatively. 

J Kido, H Shionoya, and K Nagai, Single-layer white light-emitting organic electroluminescent devices based on dye-dispersed poly(Y-vinylcarbazolc), Appl. Phys. Lett., 67 2281-2283, 1995. 

V. Cimrova and D. Vyprachticky, Enhanced electroluminescence from light-emitting devices based on poly(9,9-dihexadecylfluorene- 2,7-diyl) and polysilane blends, Appl. Phys. Lett., 82 642-644, 2003. 

F. Geiger, M. Stoldt, H. Schweizer, P. Bauerle, and E. Umbach, Electroluminescence from oligothiophene-based light-emitting devices, Adv. Mater., 5 922-925, 1993. 

J. Kido, M. Kimura, and K. Nagai, Multilayer white light emitting organic electroluminescent device, Science, 267 1332-1334 (1995). 

PE Burrows, Z Shen, V Bulovic, DM McCarty, SR Forrest, JA Cronin, and ME Thompson, Relation between electroluminescence and current transport in organic heterojunction light-emitting devices, J. Appl. Phys., 79 7991-8006, 1996. 

Blue luminescent materials for organic electroluminescent devices White light-emitting organic electroluminescent devices Blue organic electroluminescent devices... 

Tang CW, VanSlyke SA (1987) Organic electroluminescent diodes. Appl Phys Lett 51 913 Sun T, Wang ZL, Shi ZJ et al (2010) Multilayered graphene used as anode of organic light emitting devices. Appl Phys Lett 96 133301... 

Of much interest are the electroluminescence properties of conjugated polymers that allow the development of electrically switched light-emitting devices [8.257]. Electric field activated bistable molecules are expected to switch at a critical field strength [8.258]. 

Polymers based on 1,10-phenanthroline and chlorotricarbonylrhenium(I) were fabricated into single-layer light emitting devices. The turn-on voltage was 7 V with a 125 cd/m2 output. The electroluminescence maximum was broad and occurred at 700 nm [111]. 

Metal complexes with Schiff base ligands have useful applications in organic optoelectronics due to their outstanding photoluminescent (PL) and electroluminescent (EL) properties, and their ease of synthesis, which readily allows structural modification for optimization of material properties.28 Hamada and co-workers pioneered the use of zinc(II) Schiff base complexes as blue to greenish white emitters for EL devices. We have demonstrated Pt(II) Schiff base triplet emitters as yellow dopants for organic light-emitting devices... 

The first attempt to utilize the luminescent property of a-Si H for light-emitting devices can be traced back to the year 1976, when Pankove and Carlson (1976) demonstrated the electroluminescence in p-i-n and Schottky junctions of a-Si H at low temperatures. This was followed by... 

Rhenium(I) tricarbonyl-2,2 -bipyridine moieties were used to cap both ends of a poly fluorine, yielding Re-capped Re(bpy)(CO)3(py)-X-(py)(CO)3(bpy)Re 2+ polymers, where X = polyfluorene [51, 52], The polymers with and without the Re caps were spin-coated from their solutions in CH2C12 onto an ITO surface previously modified with a layer of poly(styrene sulfonic acid), doped with poly(ethylenedioxythiophene). The LED (light-emitting device) was then topped with a layer of Ca/Al. The photoluminescence (PL) and electroluminescence seen were consistent with the presence of [Re(bpy)(CO)3(py)]+ [158],... 

Interest surged in studies of fluorescence after the discovery of electroluminescence from PPV (Burroughes et al., 1990), because of its potential for practical application in light emitting devices (LEDs). Electroluminescence is fluorescent emission produced by the recombination of electrons and holes injected into a thin film of conjugated polymer, and will be discussed in the next section. If photoluminescent emission from a polymer is weak, then the electroluminescence is unlikely to be of practical significance, and consequently studies of photoluminescence and photoluminescent quantum efficiency have been used as a means of selecting polymers likely to be useful in LEDs. 

Figure 11.29 Square symbols-the EL spectrum of the device ITO/PVK/Tmcomplex/Al at drive voltage 10 V solid line - the PL spectrum of the Tm(ACAC)3(phen) powder (excitation wavelength 350 nm) [65]. (Reproduced from Synthetic Metals, 104, Z.R. Hong et al., Spectrally-narrow blue light-emitting organic electroluminescent devices utihzing thulium complexes, 165-168, 1999, with permission from Elsevier.)...

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