Electroluminescent cells

There are also several proposals to use anodic aluminum oxides in producing optoelectronic devices. Porous oxides may find use as antireflecting coatings for optical pathways. Anodic alumina films doped by Eu and Tb are promising for application in electroluminescent cells for TEELs.28... 

The luminescence properties of the decatungstolanthanate anions, especially [Eu(W5Oi8)2]9 , have attracted considerable attention, both in the solid state and solution (Blasse et al., 1981a, 1981b Blasse and Zonnevijlle, 1982 Ballardini et al., 1983 Darwent et al., 1986 Blasse, 1988 Sugeta and Yamase, 1993 Ozeki and Ya-mase, 1993c Lis et al., 2003). Electroluminescence cells based on alkaline earth metal salts of the europium anion have been described (Yamase and Ueda, 1993) and the results of pulse- and continuous-radiolysis of solutions of the europium and neodymium anions have been reported (Mulazzani et al., 1985). 

M. Sakakibara, Y. Takeuchi, and D.-k. Ding. Electroluminescent material and electroluminescent cell. US Patent 6451458, assigned to JSR Corporation (Tokyo, JP) International Center for Materials Research (Kawasaki, JP) TECO Electric Machinery Co., Ltd. (Taipei, TW), September 17, 2002. 

Tang CW (1982) Organic electroluminescent cell. U.S. Patent Number 4,356,429 (Eastman... 

Dresner J, Goodman AM (1970) Anthracene electroluminescent cells with tunnel-injection cathode. Proc IEEE 58 1868-1869... 

Figure 3.15 Sample configuration and plot of the emission efficiency vs. number of transferred layers for a metal-LB film-semiconductor electroluminescent cell.

Figure 14.29. Schematic diagram of an electroluminescent cell. (Reproduced by permission of Elsevier Sequoia from ref. 213.)...

Numerous ternary systems are known for II-VI structures incorporating elements from other groups of the Periodic Table. One example is the Zn-Fe-S system Zn(II) and Fe(II) may substimte each other in chalcogenide structures as both are divalent and have similar radii. The cubic polymorphs of ZnS and FeS have almost identical lattice constant a = 5.3 A) and form solid solutions in the entire range of composition. The optical band gap of these alloys varies (rather anomalously) within the limits of the ZnS (3.6 eV) and FeS (0.95 eV) values. The properties of Zn Fei-xS are well suited for thin film heterojunction-based solar cells as well as for photoluminescent and electroluminescent devices. 

Strickert HH, Tong JR, EUis AB (1982) Luminescent photoelectrochemical cells. 6. Spatial aspects of the photoluminescence and electroluminescence of cadmium selenide electrodes. J Am Chem Soc 104 581-588... 

Interfaces between two different media provide a place for conversion of energy and materials. Heterogeneous catalysts and photocatalysts act in vapor or liquid environments. Selective conversion and transport of materials occurs at membranes of biological tissues in water. Electron transport across solid/solid interfaces determines the efficiency of dye-sensitized solar cells or organic electroluminescence devices. There is hence an increasing need to apply molecular science to buried interfaces. 

A large number of possible applications of arrays of nanoparticles on solid surfaces is reviewed in Refs. [23,24]. They include, for example, development of new (elect-ro)catalytical systems for applications as chemical sensors, biosensors or (bio)fuel cells, preparation of optical biosensors exploiting localized plasmonic effect or surface enhanced Raman scattering, development of single electron devices and electroluminescent structures and many other applications. 

Incorporated in a device, the LPCVD -Si H material shows electroluminescence only in reverse bias [673]. The mechanism is similar to the one described for c-Si. The PECVD a-Si H material was incorporated in a p-i-n solar cell structure, with a thickness of the intrinsic layer of 500 nm (see Section 1.11.1). Oxygen was coimplanted at 80 keV (3.2 x 10 O/em-) and at 120 keV (5.5 x lO 0/cm ), which resulted in a roughly constant oxygen concentration of 1.0% in the Er projected range in the middle of the intrinsic a-Si H layer. Electroluminescence is observed under forward bias [674]. 

Y Cao, G Yu, AJ Heeger, and CY Yang, Efficient, fast response light-emitting electrochemical cells electroluminescent and solid electrolyte polymers with interpenetrating network morphology, Appl. Phys. Lett., 68 3218-3220, 1996. 

The conversion of light to electric current in photovoltaic devices is the direct inversion of the electroluminescent process in OLEDs, thus it is not surprising that the same molecular glasses as described above have also been used for the realization of solar cells. There are at least two different types of approaches, however, that shall be described now. 

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