Polymer-based electroluminescence

B Grem, G Leditzky, B Ullrich, and G Leising, Blue electroluminescent device based on a conjugated polymer, Synth. Met., 51 383-389, 1992. 

J Kido, M Kohda, K Okuyama, and K Nagai, Organic electroluminescent devices based on molecularly doped polymers, Appl. Phys. Lett., 61 761-763, 1992. 

Optically detected magnetic resonance (ODMR) studies of -iT-conjugated polymer-based hght emitting diodes (LEDs) J. Shinar Organic Electroluminescent Materials and Devices, S. Miyata and H.S. Nalwa, Eds., Gordon and Breach, Amsterdam, pp.177-202... 

J.-H. Lee, J.-W. Park, and S.-K. Choi, Synthesis and electroluminescent property of a new conjugated polymer based on carbazole derivative poly(3,6-lV-2-ethylhexyl carbazolyl cyanoter-ephthalidene), Synth. Met., 88 31-35, 1997. 

BH Cumpston and KF Jensen, Electromigration of aluminum cathodes in polymer-based electroluminescent devices, Appl. Phys. Lett., 69 3941-3943, 1996. 

Electroluminescence. In Section 6.3.2.5, we saw that some materials—in particular, semiconductors—can reemit radiation after the absorption of light in a process called photoluminescence. A related type of emission process, which is common in polymer-based semiconductors, called electroluminescence, results when the electronic excitation necessary for emission is brought about by the application of an electric field rather than by incident photons. The electric field injects electrons into the conduction band, and holes into the valence band, which upon recombination emit light. 

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]. 

Polymer-based electroluminescent materials are very prospective for many apvplications, for instance, OLEDs are now commercialized in display fields. The efficient device operation... 

High-resolution circuitry and active devices employing Langmuir-Blodgett film techniques or polymer-based transistors are being considered for the sophisticated electronics required in future vehicles. Temperature or energy balance in the vehicle could be controlled through conductive polymers or semiconductor deposits on electrochromic windows. Electroluminescent liquid crystals and fluorescent and electrochromic materials used for visual displays show promise for future development. 

Photoconductivity is based on the conversion of light to electricity. The reverse phenomenon, electroluminescence, is based on the conversion of electricity to light. Electroluminescence is useful for flat-panel display and 11-VI semiconductors such as ZnS are employed for this purpose [132], The current trend is toward the development of polymeric electroluminescent material for their processing flexibility [133,134]. It has already been demonstrated that properly doped semiconductor nanoclusters such as ZnIMn1 IS emits light efficiently [135], With the demonstration of photoconductivity [101 103] these nanocluster-doped polymers can become interesting candidates of electroluminescent materials. No experimental work has been performed yet. 

Poly(NBE)-based electroluminescent polymers have been prepared from l,4-bis[2-(3,4,5-trimethoxy-phenyl)ethenyl]benzene-derivatized norbomenes (Figure 8).Single layers of this polymer, which may... 

Figure 10. Electroluminescent device based on diphenylanthracene and oxadiazolenorbornene polymers. ITO = indium—tin oxide.

Further advances in the chemistry of processible conjugated polymers and focused work on the physics of electroluminescence in these materials have led to the development of flexible, almost entirely metal-free LEDs [55]. These polymer-based LEDs could be competitive in display applications because of the potential ease, low cost of fabrication, and large surface area of devices based upon processible polymers. 

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